Merge pull request 'Refactor Comments' (#6) from refactor/comments into main

Reviewed-on: #6

API/FrameHookContext.cs

@@ -18,6 +18,21 @@ namespace ADOFAIRenderer.API;
 /// When <c>RenderFPS</c> exceeds <c>VideoFPS</c>, intermediate game rendering frames are skipped and the hook
 /// will <b>not</b> be invoked on every rendered game frame.
 /// </para>
+/// <para>
+/// <b>Ping-pong model:</b> the renderer owns two RenderTextures with the size and format of the game frame.
+/// <see cref="Source"/> is the current frame, <see cref="Destination"/> is the buffer the next pass writes.
+/// A pass draws from <see cref="Source"/> into <see cref="Destination"/> and then calls <see cref="Swap"/>, which makes
+/// the written buffer the new <see cref="Source"/>. <see cref="Blit(Material, int)"/>, and by default
+/// <see cref="DrawToDestination"/> and <see cref="ExecuteCommandBuffer"/>, swap automatically. The texture in
+/// <see cref="Current"/> after the last hook is encoded. When no hook swaps or replaces the frame, the game frame is
+/// encoded unchanged. The first <see cref="Source"/> of every frame is the game's own frame texture
+/// (<see cref="OriginalSource"/>); do not write into it.
+/// </para>
+/// <para>
+/// <b>Threading and lifetime:</b> hooks run on the main Unity thread at the end of the frame, after the game has
+/// rendered. The textures are valid only during the hook call: do not keep references to <see cref="Source"/>,
+/// <see cref="Destination"/> or the context. <c>RenderTexture.active</c> is restored after all hooks have run.
+/// </para>
 /// </remarks>
 [SuppressMessage("ReSharper", "UnusedType.Global")]
 [SuppressMessage("ReSharper", "UnusedMember.Global")]
@@ -25,12 +40,22 @@ namespace ADOFAIRenderer.API;
 [SuppressMessage("ReSharper", "UnusedAutoPropertyAccessor.Global")]
 public class FrameHookContext
 {
+    /// <summary>Game frame of this capture (camera quad texture); never written by the context.</summary>
     private RenderTexture _originalSource = null!;
+
+    /// <summary>First ping-pong buffer, owned by FrameHookPipeline.</summary>
     private RenderTexture _pingRT = null!;
+
+    /// <summary>Second ping-pong buffer, owned by FrameHookPipeline.</summary>
     private RenderTexture _pongRT = null!;
 
+    /// <summary>Current frame: the original source, a ping-pong buffer, or a texture set by ReplaceCurrent.</summary>
     private RenderTexture _currentSource = null!;
+
+    /// <summary>Buffer the next pass writes: always the ping or pong buffer.</summary>
     private RenderTexture _currentDestination = null!;
+
+    /// <summary>True after the first Swap or ReplaceCurrent of this frame.</summary>
     private bool _hasModified;
 
     /// <summary>
@@ -45,6 +70,7 @@ public class FrameHookContext
 
     /// <summary>
     /// The active <see cref="RenderTexture"/> representing the current state of the modified frame.
+    /// Same texture as <see cref="Source"/>; after the last hook it is the frame that gets encoded.
     /// </summary>
     public RenderTexture Current => _currentSource;
 
@@ -59,7 +85,7 @@ public class FrameHookContext
     public bool HasModified => _hasModified;
 
     /// <summary>
-    /// The sequential 0-based index of the video frame currently being encoded.
+    /// The sequential 0-based index of the video frame currently being captured (its position in the output video).
     /// </summary>
     public long FrameIndex { get; private set; }
 
@@ -69,12 +95,13 @@ public class FrameHookContext
     public long VideoFrameIndex => FrameIndex;
 
     /// <summary>
-    /// The sequential 0-based index of the game render frame.
+    /// The sequential 0-based index of the game render frame, counted from the start of capture.
+    /// With <c>RenderFPS</c> above the video frame rate it advances by more than one between hook calls.
     /// </summary>
     public long RenderFrameIndex { get; private set; }
 
     /// <summary>
-    /// The timestamp of the current frame in seconds relative to video start.
+    /// The timestamp of the current frame in seconds relative to video start (<see cref="FrameIndex"/> / <see cref="VideoFPS"/>).
     /// </summary>
     public double VideoTime { get; private set; }
 
@@ -84,30 +111,32 @@ public class FrameHookContext
     public double DeltaTime => VideoFPS > 0 ? 1.0 / VideoFPS : 0.0;
 
     /// <summary>
-    /// The width of the frame in pixels.
+    /// The width of the frame in pixels (width of the current <see cref="Source"/>).
     /// </summary>
     public int Width => _currentSource.width;
 
     /// <summary>
-    /// The height of the frame in pixels.
+    /// The height of the frame in pixels (height of the current <see cref="Source"/>).
     /// </summary>
     public int Height => _currentSource.height;
 
     /// <summary>
-    /// The configured render frames per second.
+    /// The configured render frames per second (game frames simulated per second of render time).
     /// </summary>
     public double RenderFPS { get; private set; }
 
     /// <summary>
-    /// The output video frames per second.
+    /// The output video frames per second: the effective rate, min(configured <c>VideoFPS</c>, <see cref="RenderFPS"/>).
     /// </summary>
     public double VideoFPS { get; private set; }
 
     /// <summary>
-    /// The number of successful modification passes completed for the current frame.
+    /// The number of modification passes completed for the current frame (calls of <see cref="Swap"/> and
+    /// <see cref="ReplaceCurrent"/>, including the automatic swaps of the helper methods). 0 at the start of every frame.
     /// </summary>
     public int PassCount { get; private set; }
 
+    /// <summary>Creates a context for the first frame; see <see cref="Reset"/> for the parameters.</summary>
     internal FrameHookContext(
         RenderTexture originalSource,
         RenderTexture pingRT,
@@ -122,6 +151,10 @@ public class FrameHookContext
         Reset(originalSource, pingRT, pongRT, firstDestination, frameIndex, renderFrameIndex, videoTime, renderFps, videoFps);
     }
 
+    /// <summary>
+    /// Prepares the context for a new frame: Source = <paramref name="originalSource"/>, Destination =
+    /// <paramref name="firstDestination"/> (ping or pong), not modified, PassCount 0, and the frame metadata.
+    /// </summary>
     internal void Reset(
         RenderTexture originalSource,
         RenderTexture pingRT,
@@ -152,6 +185,11 @@ public class FrameHookContext
     /// <summary>
     /// Blits from <see cref="Source"/> to <see cref="Destination"/> using the specified <see cref="Material"/> and automatically swaps ping-pong buffers.
     /// </summary>
+    /// <remarks>
+    /// Uses <c>Graphics.Blit</c>, which binds <see cref="Source"/> as the material's <c>_MainTex</c> and changes
+    /// <c>RenderTexture.active</c>.
+    /// Reference: https://docs.unity3d.com/ScriptReference/Graphics.Blit.html
+    /// </remarks>
     /// <param name="material">The material containing the shader to apply, or <c>null</c> for a standard copy.</param>
     /// <param name="pass">The shader pass index to use, or -1 to execute all passes.</param>
     public void Blit(Material? material = null, int pass = -1)
@@ -174,6 +212,10 @@ public class FrameHookContext
     /// <summary>
     /// Blits from a custom source <see cref="Texture"/> to <see cref="Destination"/> using the specified <see cref="Material"/> and automatically swaps ping-pong buffers.
     /// </summary>
+    /// <remarks>
+    /// The current <see cref="Source"/> is not read; the result replaces the frame. <paramref name="customSource"/> is
+    /// stretched to the size of <see cref="Destination"/>.
+    /// </remarks>
     /// <param name="customSource">The custom source texture to blit from.</param>
     /// <param name="material">The material containing the shader to apply, or <c>null</c> for a standard copy.</param>
     /// <param name="pass">The shader pass index to use, or -1 to execute all passes.</param>
@@ -200,6 +242,7 @@ public class FrameHookContext
     /// <summary>
     /// Copies the contents of <see cref="Source"/> into <see cref="Destination"/> without swapping buffers.
     /// Call this before drawing custom overlays into <see cref="Destination"/> if you wish to preserve the background.
+    /// Does not count as a modification; call <see cref="Swap"/> after drawing to make the result the current frame.
     /// </summary>
     public void Copy()
     {
@@ -207,7 +250,8 @@ public class FrameHookContext
     }
 
     /// <summary>
-    /// Clears <see cref="Destination"/> with the specified color.
+    /// Clears <see cref="Destination"/> with the specified color (color only; no depth buffer is cleared).
+    /// Does not swap; the previous <c>RenderTexture.active</c> is restored.
     /// </summary>
     /// <param name="clearColor">The color to clear with, or <c>null</c> for <see cref="Color.clear"/>.</param>
     public void ClearDestination(Color? clearColor = null)
@@ -261,6 +305,11 @@ public class FrameHookContext
     /// <summary>
     /// Executes a <see cref="CommandBuffer"/> against the GPU and optionally swaps buffers.
     /// </summary>
+    /// <remarks>
+    /// The context does not set a render target for the command buffer: the commands must render into
+    /// <see cref="Destination"/> themselves (for example with <c>SetRenderTarget</c> or <c>Blit(Source, Destination)</c>),
+    /// so build or update the buffer inside the hook with the current <see cref="Source"/> and <see cref="Destination"/>.
+    /// </remarks>
     /// <param name="commandBuffer">The command buffer to execute.</param>
     /// <param name="autoSwap">If <c>true</c> (default), automatically calls <see cref="Swap"/> after execution.</param>
     /// <exception cref="ArgumentNullException">Thrown when <paramref name="commandBuffer"/> is null.</exception>
@@ -278,6 +327,11 @@ public class FrameHookContext
     /// Swaps the active <see cref="Source"/> and <see cref="Destination"/> ping-pong buffers.
     /// Call this after manually writing or rendering into <see cref="Destination"/> so that subsequent hooks or the video encoder read the updated frame.
     /// </summary>
+    /// <remarks>
+    /// After the call, <see cref="Source"/> is the buffer that was <see cref="Destination"/>, and <see cref="Destination"/>
+    /// is the other ping-pong buffer (its content is left over from an earlier pass or frame; the next pass overwrites it).
+    /// A texture set by <see cref="ReplaceCurrent"/> is dropped by a swap.
+    /// </remarks>
     public void Swap()
     {
         _hasModified = true;
@@ -291,6 +345,12 @@ public class FrameHookContext
     /// <summary>
     /// Replaces the current modified frame texture with a custom <see cref="RenderTexture"/>.
     /// </summary>
+    /// <remarks>
+    /// The texture becomes <see cref="Source"/> / <see cref="Current"/>; <see cref="Destination"/> is unchanged.
+    /// The texture is read back for encoding when it is still current after the last hook, so it must stay alive and
+    /// unchanged until the end of the hook chain, and it should have the frame's width, height and a format the capture
+    /// can read: the capture sizes its buffers from the texture, and the encoder expects the render resolution.
+    /// </remarks>
     /// <param name="customTexture">The custom texture to set as the active frame.</param>
     /// <exception cref="ArgumentNullException">Thrown when <paramref name="customTexture"/> is null.</exception>
     public void ReplaceCurrent(RenderTexture customTexture)

API/IFrameHook.cs

@@ -9,6 +9,8 @@ namespace ADOFAIRenderer.API;
 /// <b>Execution Frequency Note:</b> Frame hooks are only invoked for frames that are actually encoded into the final video (<c>VideoFPS</c>).
 /// When <c>RenderFPS</c> is higher than <c>VideoFPS</c>, intermediate game render frames are skipped and this hook
 /// will <b>not</b> be called on every game frame.
+/// Register an implementation per render with <see cref="RenderSession.AddFrameHook(IFrameHook)"/> or for every render
+/// with <see cref="RenderSession.AddGlobalFrameHook(IFrameHook)"/>.
 /// </remarks>
 [SuppressMessage("ReSharper", "UnusedType.Global")]
 public interface IFrameHook
@@ -18,6 +20,10 @@ public interface IFrameHook
     /// </summary>
     /// <remarks>
     /// This method is not called on every rendered game frame if <c>RenderFPS</c> exceeds <c>VideoFPS</c>.
+    /// It is called on the main Unity thread at the end of the frame. Draw from <see cref="FrameHookContext.Source"/>
+    /// into <see cref="FrameHookContext.Destination"/> and swap (see <see cref="FrameHookContext"/>); returning without
+    /// a swap leaves the frame unchanged. Do not keep the context or its textures after returning.
+    /// An exception thrown here is logged and the next hook still runs.
     /// </remarks>
     /// <param name="context">The frame hook context providing access to ping-pong textures and frame metadata.</param>
     void OnRenderFrame(FrameHookContext context);

API/RenderResult.cs

@@ -7,6 +7,9 @@ namespace ADOFAIRenderer.API;
 /// <summary>
 /// Represents the result and metadata of a completed or canceled render session.
 /// </summary>
+/// <remarks>
+/// Passed to the completion callback registered with <see cref="RenderSession.OnComplete"/>. Immutable.
+/// </remarks>
 [SuppressMessage("ReSharper", "UnusedType.Global")]
 [SuppressMessage("ReSharper", "MemberCanBePrivate.Global")]
 public class RenderResult
@@ -17,7 +20,10 @@ public class RenderResult
     public bool Success { get; }
 
     /// <summary>
-    /// The absolute output path of the rendered video file. Empty string if rendering failed or output was not created.
+    /// The output path of the rendered video file: the path given to <see cref="RenderSession.WithOutputPath"/> as passed
+    /// (relative if it was relative), or the path of the time-stamped file in the output directory chosen in the mod
+    /// settings (by default &lt;game root&gt;/Render).
+    /// Empty string if rendering failed or was cancelled (the unfinished file is deleted).
     /// </summary>
     public string OutputPath { get; }
 
@@ -27,12 +33,13 @@ public class RenderResult
     public long TotalFrames { get; }
 
     /// <summary>
-    /// The calculated video duration in seconds (based on TotalFrames and FPS).
+    /// The calculated video duration in seconds: <see cref="TotalFrames"/> divided by the effective video frame rate
+    /// (min of the configured VideoFPS and RenderFPS); 0 when the frame rate is not positive.
     /// </summary>
     public double VideoDuration { get; }
 
     /// <summary>
-    /// Total wall-clock time spent rendering.
+    /// Total wall-clock time spent rendering, from the end of the countdown (start of capture) to the end of the render.
     /// </summary>
     public TimeSpan RenderDuration { get; }
 
@@ -43,6 +50,8 @@ public class RenderResult
 
     /// <summary>
     /// Error message or reason if rendering failed or was canceled; <c>null</c> on success.
+    /// A cancelled render has "Rendering was cancelled by user."; a failed render has "Rendering failed: " followed by
+    /// the reason. Use <see cref="Success"/> to test the outcome; the texts are meant for display.
     /// </summary>
     public string? ErrorMessage { get; }
     
@@ -82,6 +91,7 @@ public class RenderResult
     /// <param name="fps">The effective frames per second used to compute video duration.</param>
     /// <param name="renderDuration">Total wall-clock time spent rendering.</param>
     /// <returns>A new <see cref="RenderResult"/> representing a successful render session.</returns>
+    /// <remarks>The file size is read from disk; it is 0 when the file does not exist or cannot be read.</remarks>
     internal static RenderResult CreateSuccess(string outputPath, long totalFrames, double fps, TimeSpan renderDuration)
     {
         var fileSizeBytes = 0L;
@@ -103,6 +113,7 @@ public class RenderResult
     /// <param name="fps">The effective frames per second used to compute video duration.</param>
     /// <param name="renderDuration">Total wall-clock time spent rendering prior to termination.</param>
     /// <returns>A new <see cref="RenderResult"/> representing a failed or canceled render session.</returns>
+    /// <remarks>OutputPath is empty and FileSizeBytes is 0. A null message is replaced by a generic one.</remarks>
     internal static RenderResult CreateFailure(string? errorMessage, long totalFrames, double fps, TimeSpan renderDuration)
     {
         var videoDuration = fps > 0 ? totalFrames / fps : 0.0;

API/RenderSession.cs

@@ -10,13 +10,41 @@ using UnityEngine;
 namespace ADOFAIRenderer.API;
 
 /// <summary>
-/// Fluent builder for configuring and starting a render session.
+/// Fluent builder for configuring and starting a render session, and the registry of global frame hooks.
 /// </summary>
+/// <remarks>
+/// <para>
+/// <b>Usage:</b> create an instance, configure it with the <c>With…</c>, <c>On…</c> and <c>AddFrameHook</c> methods,
+/// then call <see cref="Start"/>. The builder's values are copied into the render when <see cref="Start"/> is called;
+/// changing the builder afterwards does not affect the running render. A builder can be reused for later renders.
+/// </para>
+/// <para>
+/// <b>Lifecycle of a render:</b> <see cref="Start"/> loads the game scene of the level. When the scene has loaded,
+/// a 3-second countdown runs, then capture starts and the level plays with the game clock driven by the render
+/// frame rate (offline, not real time). The render ends successfully <see cref="RenderConfig.DelayAfterEnd"/> seconds
+/// (render time) after the end condition first holds, or is cancelled by the user (ESC), or fails. In every case
+/// the completion callback receives a <see cref="RenderResult"/> and the game returns to the level editor.
+/// </para>
+/// <para>
+/// <b>Threading:</b> every member must be called on the main Unity thread, except the global hook members, which are
+/// thread-safe (they lock an internal object). All callbacks (end condition, completion, last update, frame hooks)
+/// are invoked on the main Unity thread.
+/// </para>
+/// <para>
+/// <b>Frame hooks</b> run on each captured video frame before it is encoded, in this order: session hooks in the order
+/// they were added, then global hooks in registration order.
+/// </para>
+/// </remarks>
 [SuppressMessage("ReSharper", "UnusedType.Global")]
 [SuppressMessage("ReSharper", "UnusedMember.Global")]
 [SuppressMessage("ReSharper", "MemberCanBePrivate.Global")]
 public class RenderSession
 {
+    /// <summary>
+    /// Handle returned by AddGlobalFrameHook. Key is the object the caller registered (delegate, material or IFrameHook)
+    /// and is used by RemoveGlobalFrameHook; Action is the delegate the pipeline invokes.
+    /// Dispose removes this exact registration once; later calls do nothing.
+    /// </summary>
     private sealed class GlobalHookRegistration : IDisposable
     {
         public object Key { get; }
@@ -37,6 +65,10 @@ public class RenderSession
         }
     }
 
+    /// <summary>
+    /// Session hook added to this builder. Key is the object the caller passed (delegate, material or IFrameHook) and
+    /// is used by RemoveFrameHook; Action is the delegate copied to the render by Start.
+    /// </summary>
     private sealed class SessionHookEntry
     {
         public object Key { get; }
@@ -49,11 +81,22 @@ public class RenderSession
         }
     }
 
+    /// <summary>Global hooks in registration order. Guarded by GlobalHooksLock.</summary>
     private static readonly List<GlobalHookRegistration> GlobalFrameHooks = new();
+
+    /// <summary>Lock for GlobalFrameHooks and _globalHooksVersion (global hooks may be changed from any thread).</summary>
     private static readonly object GlobalHooksLock = new();
+
+    /// <summary>
+    /// Incremented on every change of GlobalFrameHooks. RenderManager compares it each captured frame to rebuild its
+    /// cached hook list only after a change. Guarded by GlobalHooksLock.
+    /// </summary>
     private static int _globalHooksVersion;
 
+    /// <summary>Session hooks of this builder in the order they were added.</summary>
     private readonly List<SessionHookEntry> _frameHooks = new();
+
+    /// <summary>Autoplay setting copied to the render by Start (default true).</summary>
     private bool _auto = true;
 
     /// <summary>
@@ -63,27 +106,48 @@ public class RenderSession
     {
         /// <summary>
         /// Time-related patch controlling frame timing and clock synchronization.
+        /// While capturing, <c>Time.time</c>, <c>Time.timeAsDouble</c>, <c>Time.unscaledTime</c>,
+        /// <c>Time.unscaledTimeAsDouble</c>, <c>Time.deltaTime</c>, <c>Time.unscaledDeltaTime</c>, <c>Time.frameCount</c>
+        /// and <c>AudioSettings.dspTime</c> return values of the render clock (one frame = 1 / RenderFPS seconds),
+        /// so the game advances exactly one render frame per Unity frame regardless of how long a frame takes.
+        /// Disabling it leaves these values to Unity.
         /// </summary>
         Time,
 
         /// <summary>
         /// Screen-related patch controlling screen resolution.
+        /// While the render is active (from the countdown on), <c>Screen.width</c> and <c>Screen.height</c> return
+        /// <see cref="RenderConfig.RenderWidth"/> and <see cref="RenderConfig.RenderHeight"/>, so the game creates its
+        /// camera RenderTexture at the render resolution.
         /// </summary>
         Screen
     }
 
+    /// <summary>Time patch setting copied to the render by Start (default true).</summary>
     private bool _timePatch = true;
+
+    /// <summary>Screen patch setting copied to the render by Start (default true).</summary>
     private bool _screenPatch = true;
+
+    /// <summary>Custom output file path, or null for the default output directory.</summary>
     private string? _outputPath;
 
+    /// <summary>Notification setting copied to the render by Start (default true).</summary>
     private bool _notification = true;
     
+    /// <summary>Custom end condition, or null to keep the default (level cleared).</summary>
     private Func<bool>? _endCondition;
+
+    /// <summary>Combined completion callbacks, or null to keep the default (notification).</summary>
     private Action<RenderResult>? _onComplete;
+
+    /// <summary>Combined last-update callbacks, or null for none.</summary>
     private Action? _onLastUpdate;
 
     /// <summary>
-    /// Sets whether auto mode is enabled.
+    /// Sets whether auto mode (the game's autoplay, <c>RDC.auto</c>) is enabled during the render.
+    /// With auto mode off, the level is not played automatically; the render still enables the game's no-fail
+    /// settings (<c>scrController.noFail</c>, <c>scrController.noFailInfiniteMargin</c>).
     /// </summary>
     /// <param name="enabled"><c>true</c> to enable auto mode; otherwise, <c>false</c>. Default is <c>true</c>.</param>
     /// <returns>The current <see cref="RenderSession"/> instance for method chaining.</returns>
@@ -115,6 +179,13 @@ public class RenderSession
     /// <summary>
     /// Sets the custom condition function that determines when the render session should end.
     /// </summary>
+    /// <remarks>
+    /// The condition is polled on the main Unity thread once per frame from the start of the countdown until the render ends.
+    /// When it first returns <c>true</c>, the render continues for <see cref="RenderConfig.DelayAfterEnd"/> seconds of
+    /// render time and then finishes successfully; it is not required to stay <c>true</c>. The default condition is
+    /// that the level is cleared (<c>scrController.instance.state == States.Won</c>). Calling this method again
+    /// replaces the previous condition. Exceptions thrown by the condition are not caught.
+    /// </remarks>
     /// <param name="endCondition">A delegate returning <c>true</c> when the session end condition is met.</param>
     /// <returns>The current <see cref="RenderSession"/> instance for method chaining.</returns>
     public RenderSession WithEndCondition(Func<bool> endCondition)
@@ -126,6 +197,13 @@ public class RenderSession
     /// <summary>
     /// Sets the custom output path for the rendered file.
     /// </summary>
+    /// <remarks>
+    /// The directory of the path is created by <see cref="Start"/> when it does not exist. An existing file at the path
+    /// is overwritten. The container format follows the file extension. With <c>null</c>, the file is named
+    /// <c>yyyy-MM-dd HH-mm-ss.&lt;ext&gt;</c> (local start time, extension from <see cref="AdvancedConfig.FileExtension"/>)
+    /// in the output directory chosen in the mod settings. When the render is cancelled or fails, the unfinished file
+    /// is deleted.
+    /// </remarks>
     /// <param name="outputPath">The file path where the output will be saved, or <c>null</c> to use the default capture directory.</param>
     /// <returns>The current <see cref="RenderSession"/> instance for method chaining.</returns>
     public RenderSession WithOutputPath(string? outputPath)
@@ -137,6 +215,10 @@ public class RenderSession
     /// <summary>
     /// Sets whether desktop notifications should be displayed when rendering completes.
     /// </summary>
+    /// <remarks>
+    /// The notification is shown by the default completion callback only. When a callback is added with
+    /// <see cref="OnComplete"/>, it replaces the default callback and no notification is shown. Default is <c>true</c>.
+    /// </remarks>
     /// <param name="enabled"><c>true</c> to enable desktop notifications; otherwise, <c>false</c>.</param>
     /// <returns>The current <see cref="RenderSession"/> instance for method chaining.</returns>
     public RenderSession WithNotification(bool enabled)
@@ -148,6 +230,13 @@ public class RenderSession
     /// <summary>
     /// Adds a callback action to be invoked when the render session completes or fails.
     /// </summary>
+    /// <remarks>
+    /// Called once per render on the main Unity thread: on success after the output file has been finished, on cancel or
+    /// failure after the unfinished file has been deleted, and before the game returns to the level editor.
+    /// It is not called when the render stops because the game quits. Multiple calls combine the callbacks (invoked in
+    /// the order added). The combined callback replaces the default one, which shows the desktop notification.
+    /// An exception thrown by a callback is logged and stops the callbacks added after it.
+    /// </remarks>
     /// <param name="callback">The callback action that receives the resulting <see cref="RenderResult"/>.</param>
     /// <returns>The current <see cref="RenderSession"/> instance for method chaining.</returns>
     public RenderSession OnComplete(Action<RenderResult> callback)
@@ -159,6 +248,11 @@ public class RenderSession
     /// <summary>
     /// Adds a callback action to be invoked on the last update of each frame in the render session.
     /// </summary>
+    /// <remarks>
+    /// Called on the main Unity thread every Unity frame after all other <c>LateUpdate</c> calls, from the moment the game scene
+    /// of the render has loaded until the render ends (including the countdown, before capture starts).
+    /// Multiple calls combine the callbacks. An exception thrown by a callback is logged.
+    /// </remarks>
     /// <param name="callback">The callback action to execute.</param>
     /// <returns>The current <see cref="RenderSession"/> instance for method chaining.</returns>
     public RenderSession OnLastUpdate(Action callback)
@@ -172,9 +266,19 @@ public class RenderSession
     /// The hook can modify the rendered frame using GPU ping-pong double buffering.
     /// </summary>
     /// <remarks>
+    /// <para>
     /// <b>Execution Frequency Note:</b> This hook is invoked only for frames that are captured for the output video.
     /// When <c>RenderFPS</c> is higher than <c>VideoFPS</c>, intermediate game render frames are skipped,
     /// so this hook will <b>not</b> be called on every game frame.
+    /// </para>
+    /// <para>
+    /// The hook is called on the main Unity thread at the end of the frame, after the game has rendered it and before
+    /// the GPU readback for encoding is requested. Write the result into <see cref="FrameHookContext.Destination"/> and
+    /// swap (or use <see cref="FrameHookContext.Blit(Material, int)"/>, which swaps); a hook that does not swap leaves
+    /// the frame unchanged. An exception thrown by the hook is logged and the next hook still runs.
+    /// Session hooks apply only to the render started by <see cref="Start"/> and are discarded when it ends.
+    /// The same delegate can be added more than once; it then runs once per addition.
+    /// </para>
     /// </remarks>
     /// <param name="hook">The callback action that receives a <see cref="FrameHookContext"/>.</param>
     /// <returns>The current <see cref="RenderSession"/> instance for method chaining.</returns>
@@ -190,6 +294,13 @@ public class RenderSession
     /// Adds a material-based post-processing pass to be executed for each encoded video frame.
     /// Automatically performs a GPU blit from source to destination and swaps buffers.
     /// </summary>
+    /// <remarks>
+    /// Equivalent to a hook calling <see cref="FrameHookContext.Blit(Material, int)"/>: the current frame is bound as the
+    /// material's <c>_MainTex</c> by <c>Graphics.Blit</c>. The material is referenced, not copied, so property changes
+    /// made to it later apply to the following frames. Execution rules are the same as
+    /// <see cref="AddFrameHook(Action{FrameHookContext})"/>.
+    /// Reference: https://docs.unity3d.com/ScriptReference/Graphics.Blit.html
+    /// </remarks>
     /// <param name="material">The material containing the shader to apply.</param>
     /// <param name="pass">The shader pass index to use, or -1 to execute all passes.</param>
     /// <returns>The current <see cref="RenderSession"/> instance for method chaining.</returns>
@@ -204,6 +315,10 @@ public class RenderSession
     /// <summary>
     /// Adds a custom frame modification hook implementing <see cref="IFrameHook"/>.
     /// </summary>
+    /// <remarks>
+    /// <see cref="IFrameHook.OnRenderFrame"/> is invoked with the same rules as
+    /// <see cref="AddFrameHook(Action{FrameHookContext})"/>. Remove it with <see cref="RemoveFrameHook(IFrameHook)"/>.
+    /// </remarks>
     /// <param name="hook">The hook instance to execute.</param>
     /// <returns>The current <see cref="RenderSession"/> instance for method chaining.</returns>
     /// <exception cref="ArgumentNullException">Thrown when <paramref name="hook"/> is null.</exception>
@@ -239,6 +354,11 @@ public class RenderSession
     /// <summary>
     /// Removes a previously added frame modification hook callback from this session.
     /// </summary>
+    /// <remarks>
+    /// Removes the first entry (in the order added) whose registered object is <paramref name="hook"/> or whose delegate
+    /// equals it. When the same delegate was added several times, one call removes one addition. Does nothing when no
+    /// entry matches. Affects only renders started after this call.
+    /// </remarks>
     /// <param name="hook">The hook action to remove.</param>
     /// <returns>The current <see cref="RenderSession"/> instance for method chaining.</returns>
     public RenderSession RemoveFrameHook(Action<FrameHookContext> hook)
@@ -251,6 +371,10 @@ public class RenderSession
     /// <summary>
     /// Removes a previously added material-based post-processing pass from this session.
     /// </summary>
+    /// <remarks>
+    /// Removes every pass added with <paramref name="material"/> (any pass index). Does nothing when the material is
+    /// null or destroyed. Affects only renders started after this call.
+    /// </remarks>
     /// <param name="material">The material to remove.</param>
     /// <returns>The current <see cref="RenderSession"/> instance for method chaining.</returns>
     public RenderSession RemoveFrameHook(Material material)
@@ -271,6 +395,9 @@ public class RenderSession
     /// <summary>
     /// Removes a previously added <see cref="IFrameHook"/> from this session.
     /// </summary>
+    /// <remarks>
+    /// Removes the first entry added with this instance (reference equality). Affects only renders started after this call.
+    /// </remarks>
     /// <param name="hook">The hook instance to remove.</param>
     /// <returns>The current <see cref="RenderSession"/> instance for method chaining.</returns>
     public RenderSession RemoveFrameHook(IFrameHook hook)
@@ -294,9 +421,19 @@ public class RenderSession
     /// Registers a global frame modification hook that will execute on every render session.
     /// </summary>
     /// <remarks>
+    /// <para>
     /// <b>Execution Frequency Note:</b> Global frame hooks are executed only for frames that are captured for the output video.
     /// When <c>RenderFPS</c> is higher than <c>VideoFPS</c>, intermediate game render frames are skipped,
     /// so this hook will <b>not</b> be called on every game frame.
+    /// </para>
+    /// <para>
+    /// The registration stays active for every following render (and a render already running, from its next
+    /// captured frame) until the returned handle is disposed or the hook is removed with
+    /// <see cref="RemoveGlobalFrameHook(Action{FrameHookContext})"/> or <see cref="ClearGlobalFrameHooks"/>.
+    /// Global hooks run after the session hooks, in registration order, on the main Unity thread; an exception thrown
+    /// by the hook is logged and the next hook still runs. This method is thread-safe. Registering the same delegate
+    /// twice creates two registrations.
+    /// </para>
     /// </remarks>
     /// <param name="hook">The callback action that receives a <see cref="FrameHookContext"/>.</param>
     /// <returns>An <see cref="IDisposable"/> registration handle that unregisters the hook when disposed.</returns>
@@ -316,6 +453,10 @@ public class RenderSession
     /// <summary>
     /// Registers a global material-based post-processing pass that will execute on every render session.
     /// </summary>
+    /// <remarks>
+    /// Same lifetime and ordering as <see cref="AddGlobalFrameHook(Action{FrameHookContext})"/>; the pass is applied as
+    /// <see cref="FrameHookContext.Blit(Material, int)"/>. Thread-safe.
+    /// </remarks>
     /// <param name="material">The material containing the shader to apply.</param>
     /// <param name="pass">The shader pass index to use, or -1 to execute all passes.</param>
     /// <returns>An <see cref="IDisposable"/> registration handle that unregisters the hook when disposed.</returns>
@@ -335,6 +476,9 @@ public class RenderSession
     /// <summary>
     /// Registers a global frame modification hook implementing <see cref="IFrameHook"/>.
     /// </summary>
+    /// <remarks>
+    /// Same lifetime and ordering as <see cref="AddGlobalFrameHook(Action{FrameHookContext})"/>. Thread-safe.
+    /// </remarks>
     /// <param name="hook">The hook instance to execute.</param>
     /// <returns>An <see cref="IDisposable"/> registration handle that unregisters the hook when disposed.</returns>
     /// <exception cref="ArgumentNullException">Thrown when <paramref name="hook"/> is null.</exception>
@@ -353,6 +497,10 @@ public class RenderSession
     /// <summary>
     /// Unregisters a previously registered global frame modification hook.
     /// </summary>
+    /// <remarks>
+    /// Removes the first registration (in registration order) whose registered object is <paramref name="hook"/> or whose
+    /// delegate equals it. Thread-safe; a running render stops calling the hook from its next captured frame.
+    /// </remarks>
     /// <param name="hook">The hook action to remove.</param>
     /// <returns><c>true</c> if the hook was successfully removed; otherwise, <c>false</c>.</returns>
     public static bool RemoveGlobalFrameHook(Action<FrameHookContext> hook)
@@ -373,6 +521,7 @@ public class RenderSession
     /// <summary>
     /// Unregisters a previously registered global material-based post-processing pass.
     /// </summary>
+    /// <remarks>Removes every registration made with <paramref name="material"/> (any pass index). Thread-safe.</remarks>
     /// <param name="material">The material to remove.</param>
     /// <returns><c>true</c> if any hooks matching <paramref name="material"/> were removed; otherwise, <c>false</c>.</returns>
     public static bool RemoveGlobalFrameHook(Material material)
@@ -399,6 +548,7 @@ public class RenderSession
     /// <summary>
     /// Unregisters a previously registered global frame modification hook implementing <see cref="IFrameHook"/>.
     /// </summary>
+    /// <remarks>Removes the first registration made with this instance (reference equality). Thread-safe.</remarks>
     /// <param name="hook">The hook instance to remove.</param>
     /// <returns><c>true</c> if the hook was successfully removed; otherwise, <c>false</c>.</returns>
     public static bool RemoveGlobalFrameHook(IFrameHook hook)
@@ -416,6 +566,7 @@ public class RenderSession
         }
     }
 
+    /// <summary>Removes one registration (called by its Dispose). Does nothing when it was already removed.</summary>
     private static void RemoveGlobalRegistration(GlobalHookRegistration registration)
     {
         lock (GlobalHooksLock)
@@ -430,6 +581,10 @@ public class RenderSession
     /// <summary>
     /// Clears all registered global frame modification hooks.
     /// </summary>
+    /// <remarks>
+    /// Removes the registrations of every mod, not only the caller's. Handles returned earlier stay valid; disposing them
+    /// does nothing. Thread-safe.
+    /// </remarks>
     public static void ClearGlobalFrameHooks()
     {
         lock (GlobalHooksLock)
@@ -443,7 +598,7 @@ public class RenderSession
     }
 
     /// <summary>
-    /// Indicates whether any global frame modification hooks are currently registered.
+    /// Indicates whether any global frame modification hooks are currently registered (by any mod). Thread-safe.
     /// </summary>
     public static bool HasGlobalFrameHooks
     {
@@ -457,7 +612,7 @@ public class RenderSession
     }
 
     /// <summary>
-    /// The number of currently registered global frame modification hooks.
+    /// The number of currently registered global frame modification hooks (by any mod). Thread-safe.
     /// </summary>
     public static int GlobalFrameHookCount
     {
@@ -470,6 +625,7 @@ public class RenderSession
         }
     }
 
+    /// <summary>Change counter of the global hook list (see _globalHooksVersion). Thread-safe.</summary>
     internal static int GlobalHooksVersion
     {
         get
@@ -481,6 +637,7 @@ public class RenderSession
         }
     }
 
+    /// <summary>Appends the delegates of every global hook, in registration order, to <paramref name="destination"/>. Thread-safe.</summary>
     internal static void CopyGlobalFrameHooksTo(List<Action<FrameHookContext>> destination)
     {
         lock (GlobalHooksLock)
@@ -495,11 +652,29 @@ public class RenderSession
     /// <summary>
     /// Applies the configured flags and initiates the render session.
     /// </summary>
+    /// <remarks>
+    /// <para>
+    /// Must be called on the main Unity thread while no render is running; this method does not check for a running
+    /// render. It copies the builder's options and hooks into the render, copies <paramref name="renderConfig"/>
+    /// (later changes to the caller's object do not affect the render), creates the output directory, and starts
+    /// loading the game scene (<c>scnGame</c>) with the level. It returns immediately; the render runs over the following
+    /// frames and reports its end through the <see cref="OnComplete"/> callback.
+    /// </para>
+    /// <para>
+    /// Options that were not set keep their defaults: auto mode on, both patches on, default output path, notification
+    /// on, end condition "level cleared", default completion callback (notification), no last-update callback.
+    /// </para>
+    /// </remarks>
     /// <param name="renderConfig">The configuration settings for the render session.</param>
-    /// <param name="levelPath">The file path of the level to render.</param>
+    /// <param name="levelPath">The file path of the level to render (the .adofai file).</param>
     /// <exception cref="InvalidOperationException">Thrown when the output directory cannot be determined from the output path.</exception>
+    /// <exception cref="ArgumentException">
+    /// Thrown by the directory creation when the output path has no directory part (for example a bare file name).
+    /// </exception>
     public void Start(RenderConfig renderConfig, string levelPath)
     {
+        // Callbacks not set on this builder keep the values RenderContext holds; RenderContext.Reset at the end of every
+        // render restores the defaults.
         RenderContext.Auto = _auto;
         RenderContext.TimePatch = _timePatch;
         RenderContext.ScreenPatch = _screenPatch;

Core/Data/GlobalSettings.cs

@@ -6,29 +6,59 @@ using Newtonsoft.Json;
 
 namespace ADOFAIRenderer.Core.Data;
 
+/// <summary>
+/// Mod-wide settings that are not part of a render preset, stored as JSON in
+/// &lt;game root&gt;/UserData/ADOFAIRenderer/global_settings.json (see <see cref="GlobalSettings"/>).
+/// </summary>
 internal class GlobalConfig
 {
+    /// <summary>
+    /// Output directory chosen in the render configuration window; null or empty selects
+    /// GlobalSettings.DefaultOutputDirectory. Ignored while the directory does not exist (see EffectiveOutputDirectory).
+    /// </summary>
     public string? OutputDirectory { get; set; }
+    /// <summary>Name of the preset last selected or saved in the render configuration window; selected again when it opens.</summary>
     public string? LastPresetName { get; set; }
+    /// <summary>
+    /// True once PresetManager.EnsureDefaultPresetsCreated has written the built-in preset files. Built-in presets the user
+    /// deleted afterwards are not written again.
+    /// </summary>
     public bool DefaultPresetsInitialized { get; set; }
 }
 
+/// <summary>
+/// Loads and saves <see cref="GlobalConfig"/>. The file is read once by the static constructor and again by
+/// RenderMod.OnInitializeMelon (Load), and written by Save. Read and write errors are logged as warnings and never
+/// thrown; a file that cannot be read yields the default settings. Main thread.
+/// </summary>
 internal static class GlobalSettings
 {
+    /// <summary>MelonLoader's game root directory, or the application base directory when it is empty.</summary>
     private static string GetGameRootDir()
     {
         var root = MelonEnvironment.GameRootDirectory;
         return string.IsNullOrEmpty(root) ? AppDomain.CurrentDomain.BaseDirectory : root;
     }
 
+    /// <summary>&lt;game root&gt;/UserData/ADOFAIRenderer/global_settings.json.</summary>
     private static string SettingsFilePath =>
         Path.Combine(GetGameRootDir(), "UserData", "ADOFAIRenderer", "global_settings.json");
 
+    /// <summary>
+    /// Settings in memory. Changes are kept in memory until <see cref="Save"/> is called; <see cref="Load"/> replaces the
+    /// object.
+    /// </summary>
     public static GlobalConfig Current { get; private set; } = new();
 
+    /// <summary>Output directory used when none is configured: &lt;game root&gt;/Render.</summary>
     public static string DefaultOutputDirectory =>
         Path.Combine(GetGameRootDir(), "Render");
 
+    /// <summary>
+    /// Directory where renders without an explicit output path are written: Current.OutputDirectory when it is set and
+    /// exists, otherwise <see cref="DefaultOutputDirectory"/>. The default directory is not created here
+    /// (RenderManager.SetupCaptureDirectory creates it).
+    /// </summary>
     public static string EffectiveOutputDirectory
     {
         get
@@ -47,6 +77,10 @@ internal static class GlobalSettings
         Load();
     }
 
+    /// <summary>
+    /// Replaces <see cref="Current"/> with the content of the settings file. A missing, empty or unreadable file gives the
+    /// default settings (an unreadable file is logged as a warning).
+    /// </summary>
     public static void Load()
     {
         try
@@ -66,6 +100,10 @@ internal static class GlobalSettings
         Current = new GlobalConfig();
     }
 
+    /// <summary>
+    /// Writes <see cref="Current"/> as indented JSON to the settings file, creating the directory when needed.
+    /// Errors are logged as warnings.
+    /// </summary>
     public static void Save()
     {
         try

Core/FirstUpdateHook.cs

@@ -4,14 +4,30 @@ using UnityEngine;
 
 namespace ADOFAIRenderer.Core;
 
+/// <summary>
+/// MonoBehaviour that runs before every other script's Update (execution order int.MinValue; scripts run from the
+/// lowest order to the highest). Lives on a DontDestroyOnLoad object created by RenderMod.
+/// It performs the start-up checks (FFmpeg libraries present, NVIDIA driver version) and then advances the render
+/// frame counter through RenderManager.OnPreUpdate once per Unity frame, so every other script of that frame sees
+/// the same render time.
+/// Reference: https://docs.unity3d.com/ScriptReference/DefaultExecutionOrder.html
+/// </summary>
 [DefaultExecutionOrder(int.MinValue)]
 internal class FirstUpdateHook : MonoBehaviour
 {
+    /// <summary>True once the FFmpeg libraries were found in UserLibs (after the download UI, if it was needed).</summary>
     private bool _checkedFFmpeg;
+
+    /// <summary>True once the NVIDIA driver version check ran (it runs once per game session).</summary>
     private bool _checkedNvidiaDriver;
 
+    /// <summary>
+    /// Main thread, every frame. The checks are done in order and each one blocks the following steps while its dialog
+    /// is open: the frame counter is not advanced until both checks are done.
+    /// </summary>
     private void Update()
     {
+        // 1. FFmpeg libraries: while the download UI is open, wait. When the libraries are missing, open the download UI.
         if (!_checkedFFmpeg)
         {
             if (FFmpegDownloadUI.Instance) return;
@@ -24,6 +40,7 @@ internal class FirstUpdateHook : MonoBehaviour
             _checkedFFmpeg = true;
         }
 
+        // 2. NVIDIA driver version: waits until no other warning dialog is open, then runs once.
         if (!_checkedNvidiaDriver)
         {
             if (CommonWarningDialogUI.Instance) return;
@@ -32,12 +49,19 @@ internal class FirstUpdateHook : MonoBehaviour
             CheckNvidiaDriverWarning();
         }
 
+        // 3. Render frame counter (only counts while a render is in the OnScene stage or later).
         if (RenderManager.Instance)
         {
             RenderManager.Instance.OnPreUpdate();
         }
     }
 
+    /// <summary>
+    /// Shows a warning dialog when the active GPU is an NVIDIA GPU with a driver version below 610.00.
+    /// No dialog is shown when the GPU is not NVIDIA or the version cannot be determined (GPUUtil returns null).
+    /// Buttons: open the NVIDIA driver download page and quit the game, disable the render feature for this session
+    /// (RenderMod.IsFeatureDisabled), or continue.
+    /// </summary>
     private void CheckNvidiaDriverWarning()
     {
         var driverVer = Util.GPUUtil.GetNvidiaDriverVersion();

Core/FrameHookPipeline.cs

@@ -6,16 +6,58 @@ using UnityEngine;
 
 namespace ADOFAIRenderer.Core;
 
+/// <summary>
+/// Runs the frame hooks (session and global, see RenderSession) on a captured frame before it is read back.
+/// Owns two RenderTextures (ping and pong) with the size and format of the source frame; each hook pass reads the
+/// current frame and writes the other buffer (see FrameHookContext). One instance per render, created in
+/// RenderManager.SetupPlay and disposed when the render ends. Main thread only.
+/// </summary>
 internal class FrameHookPipeline : IDisposable
 {
+    /// <summary>First ping-pong buffer. Created by EnsureBuffers, released by ReleaseBuffers.</summary>
     private RenderTexture? _pingRT;
+
+    /// <summary>Second ping-pong buffer. Created by EnsureBuffers, released by ReleaseBuffers.</summary>
     private RenderTexture? _pongRT;
+
+    /// <summary>
+    /// Buffer returned as the output of the previous Process call (ping or pong), or null when the previous frame was
+    /// not modified by any hook. Its readback may still be in flight, so the next frame starts writing the other buffer.
+    /// </summary>
     private RenderTexture? _lastOutputRT;
+
+    /// <summary>Context object passed to the hooks; reset and reused for every frame (no allocation per frame).</summary>
     private FrameHookContext? _reusableContext;
+
+    /// <summary>Width of the current buffers in pixels (0 when no buffers exist).</summary>
     private int _width;
+
+    /// <summary>Height of the current buffers in pixels (0 when no buffers exist).</summary>
     private int _height;
+
+    /// <summary>Format of the source texture the current buffers were created for.</summary>
     private RenderTextureFormat _format;
 
+    /// <summary>
+    /// Runs <paramref name="hooks"/> in order on <paramref name="sourceTexture"/> and returns the resulting texture.
+    /// An exception thrown by a hook is logged and the remaining hooks still run.
+    /// RenderTexture.active is restored after the hooks.
+    /// </summary>
+    /// <param name="sourceTexture">Captured game frame. Hooks do not write into it (they write the ping-pong buffers).</param>
+    /// <param name="frameIndex">Video frame index (0-based) of this frame.</param>
+    /// <param name="renderFrameIndex">
+    /// Render frame index (0-based, RenderManager.frameCountForVideo): counts every game frame since capture started,
+    /// including game frames that were not captured because they fall in an already captured video frame.
+    /// </param>
+    /// <param name="videoTime">Time of this video frame in seconds from the start of the video.</param>
+    /// <param name="renderFps">Render frame rate (game frames per second).</param>
+    /// <param name="videoFps">Effective video frame rate (min(VideoFPS, RenderFPS)).</param>
+    /// <param name="hooks">Hooks to run, in order. Session hooks come before global hooks.</param>
+    /// <returns>
+    /// <paramref name="sourceTexture"/> when there are no hooks, the source is not created, the buffers could not be
+    /// created, or no hook modified the frame; otherwise the texture holding the final frame (a ping-pong buffer, or a
+    /// texture a hook passed to FrameHookContext.ReplaceCurrent).
+    /// </returns>
     public RenderTexture? Process(
         RenderTexture sourceTexture,
         long frameIndex,
@@ -81,6 +123,8 @@ internal class FrameHookPipeline : IDisposable
                 }
             }
 
+            // Current is the source when nothing was modified. A texture set by ReplaceCurrent is stored in
+            // _lastOutputRT too; it then matches neither buffer and the next frame starts with ping.
             var result = _reusableContext.Current;
             _lastOutputRT = _reusableContext.HasModified ? result : null;
             return result;
@@ -91,6 +135,12 @@ internal class FrameHookPipeline : IDisposable
         }
     }
 
+    /// <summary>
+    /// Creates the ping and pong buffers when they do not exist, were released, or the source size or format changed.
+    /// The buffers copy the source descriptor without depth, MSAA and mipmaps, and enable random write (UAV) when the
+    /// GPU supports compute shaders and random write for that format, so compute shaders can write them.
+    /// When creating them from the descriptor throws, ARGB32 buffers of the same size are created.
+    /// </summary>
     private void EnsureBuffers(RenderTexture sourceTexture)
     {
         var width = sourceTexture.width;
@@ -160,6 +210,9 @@ internal class FrameHookPipeline : IDisposable
         }
     }
 
+    /// <summary>
+    /// Releases and destroys both buffers and drops the reusable context. The next Process call creates them again.
+    /// </summary>
     public void ReleaseBuffers()
     {
         if (_pingRT)
@@ -182,6 +235,7 @@ internal class FrameHookPipeline : IDisposable
         _reusableContext = null;
     }
 
+    /// <summary>Same as <see cref="ReleaseBuffers"/>. Main thread (Object.Destroy is used).</summary>
     public void Dispose()
     {
         ReleaseBuffers();

Core/PostRenderHook.cs

@@ -5,10 +5,22 @@ using UnityEngine;
 
 namespace ADOFAIRenderer.Core;
 
+/// <summary>
+/// Per-frame hook attached to the scrCamera GameObject by RenderManager when the game scene of a render has loaded,
+/// and destroyed again when a render is cancelled or fails.
+/// Execution order int.MaxValue: its LateUpdate runs after every other script's LateUpdate of the frame.
+/// Each frame it calls RenderManager.OnLastUpdate (LateUpdate) and, after the frame has been rendered
+/// (end of frame), RenderManager.OnPostFrame with the texture shown on scrCamera's camera quad, which is the frame
+/// that gets captured.
+/// Reference: https://docs.unity3d.com/ScriptReference/DefaultExecutionOrder.html
+/// </summary>
 [DefaultExecutionOrder(int.MaxValue)]
 internal class PostRenderHook : MonoBehaviour
 {
+    /// <summary>Private field scrCamera.camQuadMesh: the MeshRenderer of the quad that displays the camera RenderTexture.</summary>
     private FieldInfo? _camQuadMeshField;
+
+    /// <summary>Cached value of camQuadMesh for the current scrCamera instance. Looked up again while it is null or destroyed.</summary>
     private MeshRenderer? _camQuadMeshRenderer;
 
     private void Awake()
@@ -16,6 +28,10 @@ internal class PostRenderHook : MonoBehaviour
         _camQuadMeshField = AccessTools.Field(typeof(scrCamera), "camQuadMesh");
     }
         
+    /// <summary>
+    /// Main thread, once per frame after all other LateUpdate calls. Runs the last-update work of RenderManager
+    /// (OnLastUpdate callbacks of the session) and schedules the end-of-frame capture.
+    /// </summary>
     private void LateUpdate()
     {
         if (RenderManager.Instance)
@@ -24,6 +40,11 @@ internal class PostRenderHook : MonoBehaviour
         PostFrameAsync().Forget();
     }
 
+    /// <summary>
+    /// Waits until the end of the current frame (after the cameras have rendered) and passes the camera quad's main
+    /// texture to RenderManager.OnPostFrame. The wait is cancelled when this component is destroyed.
+    /// The texture is null when the quad's material has no RenderTexture; OnPostFrame then only updates the audio.
+    /// </summary>
     private async UniTaskVoid PostFrameAsync()
     {
         await UniTask.WaitForEndOfFrame(this, destroyCancellationToken);

Core/PresetManager.cs

@@ -11,11 +11,16 @@ using Newtonsoft.Json.Linq;
 
 namespace ADOFAIRenderer.Core;
 
+/// <summary>A named render configuration, stored as one JSON file in the presets directory.</summary>
 public class RenderPreset
 {
+    /// <summary>Display name of the preset. A file without a name uses the file name (without extension).</summary>
     public string Name { get; set; } = string.Empty;
+
+    /// <summary>Render configuration of the preset.</summary>
     public RenderConfig Config { get; set; } = null!;
 
+    /// <summary>Returns a copy with a copied configuration.</summary>
     public RenderPreset Clone()
     {
         return new RenderPreset
@@ -26,8 +31,18 @@ public class RenderPreset
     }
 }
 
+/// <summary>
+/// Loads, saves and deletes render presets. Presets are JSON files (one per preset, file name derived from the preset
+/// name) in &lt;game root&gt;/UserData/ADOFAIRenderer/Presets. The built-in presets are written once, on first use
+/// (GlobalConfig.DefaultPresetsInitialized), so the user can edit or delete them. Main thread.
+/// </summary>
 public static class PresetManager
 {
+    /// <summary>
+    /// Built-in presets (H.264 CBR, 48 kHz stereo AAC at 256 kbps, mkv): 1080p, 1440p and 2160p at 60 FPS video.
+    /// "(4x)" presets render 240 game frames per second (4 per video frame); "(1x)" renders 60.
+    /// Video bitrates are in kbps.
+    /// </summary>
     private static readonly List<RenderPreset> DefaultPresets = new()
     {
         new RenderPreset
@@ -96,6 +111,10 @@ public static class PresetManager
         }
     };
 
+    /// <summary>
+    /// &lt;root&gt;/UserData/ADOFAIRenderer/Presets, where root is MelonLoader's game root directory, or the application
+    /// base directory when that is unavailable.
+    /// </summary>
     private static string GetPresetsDirectory()
     {
         string? root = null;
@@ -125,6 +144,10 @@ public static class PresetManager
         return Path.GetInvalidFileNameChars().Aggregate(name, (current, c) => current.Replace(c, '_'));
     }
 
+    /// <summary>
+    /// Creates the presets directory and, once per installation (GlobalConfig.DefaultPresetsInitialized), writes the
+    /// built-in presets whose files do not exist yet, then saves the flag. Errors are logged, not thrown.
+    /// </summary>
     public static void EnsureDefaultPresetsCreated()
     {
         try
@@ -164,6 +187,12 @@ public static class PresetManager
         }
     }
 
+    /// <summary>
+    /// Saves a copy of <paramref name="config"/> as preset <paramref name="name"/>, overwriting the file of the same
+    /// safe file name (see GetSafeFileName).
+    /// </summary>
+    /// <exception cref="ArgumentException">The name is empty or white space.</exception>
+    /// <exception cref="IOException">The directory or file cannot be written (not caught).</exception>
     public static void SavePreset(string name, RenderConfig config)
     {
         if (string.IsNullOrWhiteSpace(name))
@@ -195,6 +224,13 @@ public static class PresetManager
         File.WriteAllText(filePath, json);
     }
 
+    /// <summary>
+    /// Loads every *.json preset file (after creating the built-in presets on first use). Files written by older
+    /// versions are migrated in memory (old key names and flat properties moved into the nested configs); the files are
+    /// not rewritten. A file that cannot be read is logged and skipped. When two files have the same preset name
+    /// (case-insensitive), the first one in directory order is used. Returns copies of the built-in presets when the
+    /// directory does not exist.
+    /// </summary>
     public static List<RenderPreset> GetPresets()
     {
         EnsureDefaultPresetsCreated();
@@ -332,6 +368,10 @@ public static class PresetManager
         return presets;
     }
 
+    /// <summary>
+    /// Renames key <paramref name="keyBefore"/> to <paramref name="targetKey"/>: a non-null old value overwrites the target
+    /// key, and the old key is always removed.
+    /// </summary>
     private static void TryChangeKey(JObject configObj, string keyBefore, string targetKey)
     {
         var legacyToken = configObj[keyBefore];
@@ -341,6 +381,12 @@ public static class PresetManager
         configObj.Remove(keyBefore);
     }
 
+    /// <summary>
+    /// Deletes the file of preset <paramref name="name"/>: first the file with the safe file name; otherwise the first
+    /// file whose base name or stored "Name" matches (case-insensitive). Does nothing for an empty name or when no file
+    /// matches.
+    /// </summary>
+    /// <exception cref="IOException">The file with the safe file name exists but cannot be deleted (not caught).</exception>
     public static void DeletePreset(string name)
     {
         if (string.IsNullOrWhiteSpace(name)) return;

Core/RenderManager.cs

@@ -25,24 +25,61 @@ using ThreadPriority = System.Threading.ThreadPriority;
 
 namespace ADOFAIRenderer.Core;
 
+/// <summary>
+/// Progress of the current render (RenderManager.stage). Values are ordered: checks use comparisons such as
+/// stage >= OnScene.
+/// <list type="bullet">
+/// <item><c>None</c>: no render. Set at start-up and whenever a render ends, is cancelled or fails (ResetRenderState).</item>
+/// <item><c>Load</c>: RenderSession.Start was called; the game scene (scnGame) is being loaded.</item>
+/// <item><c>OnScene</c>: the game scene has loaded (RenderManager.Update set up the scene): the frame counter runs, the
+/// 3-second countdown is shown, input is ignored. Nothing is captured yet. RenderManager.IsActive is true from this stage.</item>
+/// <item><c>Render</c>: the encoder and render thread run and frames are captured (set by SetupPlay after the countdown).
+/// RenderManager.IsCapturingActive is true; the time patches replace Unity's clock with the render clock.</item>
+/// </list>
+/// </summary>
 internal enum RenderStage
 {
     None, Load, OnScene, Render
 }
 
+/// <summary>
+/// Options of the current render, copied from a <see cref="RenderSession"/> by RenderSession.Start and read by
+/// RenderManager and the Harmony patches. <see cref="Reset"/> restores the defaults when the render environment is
+/// restored (RenderManager.RestoreRenderEnvironment). Main thread only.
+/// </summary>
 internal static class RenderContext
 {
+    /// <summary>Value assigned to RDC.auto (the game's autoplay flag) when the game scene of the render has loaded.</summary>
     public static bool Auto = true;
+
+    /// <summary>
+    /// Enables the time patches (Time.time / unscaledTime / deltaTime / frameCount, AudioSettings.dspTime) while capturing,
+    /// which drive the game by the render clock (frameCount / RenderFPS) instead of real time.
+    /// </summary>
     public static bool TimePatch = true;
+
+    /// <summary>Enables the Screen.width / Screen.height patches (report the render resolution) while the render is active.</summary>
     public static bool ScreenPatch = true;
+
+    /// <summary>Output file path of the render, or null for a time-stamped file in GlobalSettings.EffectiveOutputDirectory.</summary>
     public static string? OutputPath;
         
+    /// <summary>Whether the default OnComplete callback shows an OS notification after a successful render.</summary>
     public static bool Notification = true;
+
+    /// <summary>Frame hooks of the current session, run before the global hooks (see RenderSession.AddFrameHook).</summary>
     public static readonly List<Action<FrameHookContext>> SessionFrameHooks = new();
         
+    /// <summary>Default end condition: the level is cleared (scrController state Won).</summary>
     private static readonly Func<bool> EndConditionDefault = () => scrController.instance.state == States.Won;
+
+    /// <summary>
+    /// Polled by RenderManager.Update every frame from the OnScene stage. When it first returns true, the render
+    /// continues for RenderConfig.DelayAfterEnd seconds of render time and then ends successfully.
+    /// </summary>
     public static Func<bool> EndCondition = EndConditionDefault;
 
+    /// <summary>Default completion callback: shows an OS notification for a successful render when Notification is true.</summary>
     private static readonly Action<RenderResult> OnCompleteDefault = result =>
     {
         if (result.Success && Notification)
@@ -54,11 +91,23 @@ internal static class RenderContext
             OSNotification.Show("Rendering Complete!", $"{fileString} saved successfully.", renderFolder);
         }
     };
+    /// <summary>
+    /// Called once on the main Unity thread when the render finishes (success) or is cancelled or fails.
+    /// A session callback replaces the default one, so no notification is shown when a session sets OnComplete.
+    /// Exceptions are caught and logged (RenderManager.TriggerOnComplete).
+    /// </summary>
     public static Action<RenderResult> OnComplete = OnCompleteDefault;
 
     private static readonly Action OnLastUpdateDefault = () => { };
+
+    /// <summary>
+    /// Called on the main Unity thread every frame after all other LateUpdate calls, through PostRenderHook (attached when the
+    /// game scene of the render has loaded) while the stage is Load or later.
+    /// Exceptions are caught and logged (RenderManager.TriggerOnLastUpdate).
+    /// </summary>
     public static Action OnLastUpdate = OnLastUpdateDefault;
 
+    /// <summary>Restores every option to its default and clears the session frame hooks.</summary>
     public static void Reset()
     {
         Auto = true;
@@ -74,15 +123,38 @@ internal static class RenderContext
     }
 }
     
+/// <summary>
+/// Drives a render from scene setup to the finished video file. Singleton MonoBehaviour on a DontDestroyOnLoad object
+/// created by RenderMod.
+///
+/// Flow: RenderSession.Start (stage Load) → SetupGameScene loads scnGame → Update sets up the loaded scene
+/// (stage OnScene, 3-second countdown) → SetupPlay starts the encoder and the render thread (stage Render) →
+/// every frame OnPreUpdate advances frameCount, OnPostFrame queues the audio commands and requests the GPU capture of
+/// the frame (FrameReader, AsyncGPUReadback) → readback completions add frames to ImageQueue → the render thread
+/// (RunRenderThread) encodes them in frame order together with the audio of each frame.
+///
+/// End: success (EndCondition plus DelayAfterEnd) → StopFFmpeg(true) → StopRenderCoroutine waits for the render
+/// thread to finish the file → EndRender. Cancel (ESC) or failure → StopFFmpeg(false) → EndRender, which deletes the
+/// unfinished file. Encoder initialization failure → StopFFmpeg(false) → RestoreRenderEnvironment and an error dialog.
+///
+/// Threads: the main Unity thread runs every public method unless noted otherwise. The render thread reads
+/// ImageQueue (lock on ImageQueue), passCount (render thread only while it runs), endRequested / endSuccessful
+/// (volatile), the abort state (volatile, written under _abortStateLock) and lastRequestedVideoFrameIndex
+/// (Volatile.Read/Write). FrameAvailableEvent wakes the render thread, FrameDequeuedEvent wakes the throttle loop.
+/// </summary>
 internal class RenderManager : MonoBehaviour
 {
-    // Singleton Accessors
+    /// <summary>The single instance, set in Awake. Unity null checks (<c>if (Instance)</c>) are used before access.</summary>
     public static RenderManager Instance { get; private set; } = null!;
+
+    /// <summary>True from the OnScene stage (scene set up, countdown running) until the render ends.</summary>
     public static bool IsActive => Instance && Instance.stage >= RenderStage.OnScene;
+
+    /// <summary>True while frames are captured and encoded (Render stage). The time patches apply only then.</summary>
     public static bool IsCapturingActive => Instance && Instance.stage >= RenderStage.Render;
 
     /// <summary>
-    /// Maximum number of frames in ImageQueue. The main thread waits (throttles) while the queue holds more frames.
+    /// Maximum number of frames in ImageQueue. The main Unity thread waits (throttles) while the queue holds more frames.
     /// </summary>
     public const int MaxQueuedFrames = 64;
 
@@ -104,26 +176,66 @@ internal class RenderManager : MonoBehaviour
     public int QueueFrameLimit { get; private set; } = MaxQueuedFrames;
         
     // Statistics
+
+    /// <summary>
+    /// Number of video frames sent to the encoder in this render. Incremented by the render thread (Interlocked),
+    /// read with Interlocked.Read by the main Unity thread (result, debug monitor). Reset in SetupPlay.
+    /// </summary>
     public long framesSent;
+
+    /// <summary>Wall-clock time of the render from the end of the countdown (SetupPlay) to BuildResult.</summary>
     private readonly Stopwatch _renderStopwatch = new();
 
     // Core Render Configuration and Path
+
+    /// <summary>
+    /// Seconds left in the countdown before capture starts (3 when the scene is set up, decremented once per real-time
+    /// second by SetupPlay). Shown by scrShowIfDebugPatch and read by scrPlayerManagerPatch.
+    /// </summary>
     public int countdown;
+
+    /// <summary>
+    /// Render frame counter: incremented once per Unity frame by OnPreUpdate from the OnScene stage and reset to 0 when
+    /// capture starts (SetupPlay). The render clock is frameCount / RenderFPS seconds (AudioTime, time patches).
+    /// Main thread only.
+    /// </summary>
     public long frameCount;
+
+    /// <summary>
+    /// Set by SetupGameScene; scrPressToStartPatch consumes it (sets it back to false) to skip the press-to-start
+    /// screen once. Cleared by StopFFmpeg.
+    /// </summary>
     public bool skipPressToStart;
+
+    /// <summary>Path of the level file to render (ADOBase.levelPath of the editor, or the path given to RenderSession.Start).</summary>
     public string levelPath = "";
+
+    /// <summary>Serializes changes of the abort state (_isRenderCancelled, _renderFailed, _failureReason).</summary>
     private readonly object _abortStateLock = new();
+
+    /// <summary>The render was cancelled (ESC, or a non-successful stop). Written under _abortStateLock, read by any thread.</summary>
     private volatile bool _isRenderCancelled;
+
+    /// <summary>The render failed (MarkFailed). Written under _abortStateLock, read by any thread.</summary>
     private volatile bool _renderFailed;
+
+    /// <summary>Reason given to the first MarkFailed call of this render; null when the render has not failed.</summary>
     private volatile string? _failureReason;
 
+    /// <summary>True when the render was cancelled. Thread-safe read.</summary>
     // ReSharper disable once MemberCanBePrivate.Global
     public bool IsRenderCancelled => _isRenderCancelled;
+
+    /// <summary>True when the render failed. Thread-safe read.</summary>
     public bool IsRenderFailed => _renderFailed;
     
-    // Cancelled and failed are mutually exclusive; this is true for either (render must stop).
+    /// <summary>
+    /// True when the render was cancelled or failed (the two are mutually exclusive) and must stop.
+    /// Read by the render thread before each frame and by readback completions. Thread-safe read.
+    /// </summary>
     public bool IsRenderAborted => _isRenderCancelled || _renderFailed;
 
+    /// <summary>Marks the render as cancelled unless it has already failed (a failure keeps its reason).</summary>
     private void MarkCancelled()
     {
         lock (_abortStateLock)
@@ -132,7 +244,10 @@ internal class RenderManager : MonoBehaviour
         }
     }
 
-    // The first failure reason wins; ignored once the render is already cancelled or failed.
+    /// <summary>
+    /// Marks the render as failed with <paramref name="reason"/> (shown in the result message as "Rendering failed: reason").
+    /// The first failure reason wins; ignored once the render is already cancelled or failed. Callable from any thread.
+    /// </summary>
     private void MarkFailed(string reason)
     {
         lock (_abortStateLock)
@@ -143,6 +258,7 @@ internal class RenderManager : MonoBehaviour
         }
     }
 
+    /// <summary>Clears cancelled, failed and the failure reason. Called when a new encoder starts (StartFFmpegThread).</summary>
     private void ClearAbortState()
     {
         lock (_abortStateLock)
@@ -153,30 +269,70 @@ internal class RenderManager : MonoBehaviour
         }
     }
 
+    /// <summary>Error message of the RenderResult of an aborted render (failure reason, or the cancel message).</summary>
     private string BuildAbortMessage() => IsRenderFailed
         ? $"Rendering failed: {_failureReason ?? "unknown error"}"
         : "Rendering was cancelled by user.";
+
+    /// <summary>
+    /// Configuration of the current render: a copy made by RenderSession.Start, so values adjusted during the render
+    /// (the audio sample rate in SetupPlay) do not change the caller's object. Read by the main Unity thread, the render
+    /// thread (audio settings) and the patches. Null until the first render starts.
+    /// </summary>
     public RenderConfig Configuration = null!;
 
     // Render Sessions State (OOP Instance Fields)
+
+    /// <summary>Current stage of the render. Written on the main Unity thread; read by the render thread in TryDequeueNextFrame.</summary>
     public RenderStage stage = RenderStage.None;
+
+    /// <summary>Time.timeAsDouble when capture started. The time patch returns timeBase + frameCount / RenderFPS.</summary>
     public double timeBase;
+
+    /// <summary>Time.unscaledTimeAsDouble when capture started. The time patch returns unscaledTimeBase + frameCount / RenderFPS.</summary>
     public double unscaledTimeBase;
+
+    /// <summary>
+    /// AudioSettings.dspTime when capture started (seconds). The dspTime patch returns dspTimeBase + frameCount / RenderFPS;
+    /// audio command times are stored relative to it (scheduled dspTime - dspTimeBase).
+    /// </summary>
     public double dspTimeBase;
+
+    /// <summary>Time.frameCount when capture started. The frameCount patch returns frameCountBase + frameCount.</summary>
     public int frameCountBase;
         
+    /// <summary>
+    /// Offline mixer of the song and sound effects of this render; null when audio is not rendered or no render runs.
+    /// Created in SetupPlay. Commands are added on the main Unity thread (OnPostFrame, audio patches), mixing runs on the
+    /// render thread (WriteAudioForFrame); the mixer synchronizes the two internally.
+    /// </summary>
     public OfflineAudioMixer? AudioMixer { get; private set; }
 
     /// <summary>Render time of the current frame in seconds (frameCount / RenderFPS), the time base of audio commands.</summary>
     public double AudioTime => frameCount / Configuration.RenderFPS;
+    /// <summary>
+    /// Number of audio samples (per channel) to write after each video frame, so that the audio stays aligned with
+    /// the video frame times at the effective video frame rate. Created in SetupPlay when audio is rendered;
+    /// used by the render thread only.
+    /// </summary>
     private AudioSyncCalculator? SyncCalculator { get; set; }
 
+    /// <summary>GPU capture of frames (color conversion and AsyncGPUReadback). Created in SetupPlay after the encoder started.</summary>
     private FrameReader? _frameReader;
+
+    /// <summary>Frame hook runner of this render. Created in SetupPlay, disposed by ResetFrameHookState.</summary>
     private FrameHookPipeline? _frameHookPipeline;
+
+    /// <summary>Session hooks followed by global hooks, rebuilt when the global hook version changes.</summary>
     private readonly List<Action<FrameHookContext>> _activeHooksCache = new();
+
+    /// <summary>RenderSession.GlobalHooksVersion the cache was built for; -1 forces a rebuild.</summary>
     private int _cachedGlobalHooksVersion = -1;
+
+    /// <summary>True when _activeHooksCache is not empty.</summary>
     private bool _hasActiveHooksCached;
 
+    /// <summary>True when at least one session or global frame hook is registered. Main thread.</summary>
     public bool HasActiveFrameHooks
     {
         get
@@ -186,6 +342,11 @@ internal class RenderManager : MonoBehaviour
         }
     }
 
+    /// <summary>
+    /// Rebuilds the active hook list when the global hook registrations changed since the last build.
+    /// Session hooks are only read on a rebuild; SetupPlay forces one (version -1) at the start of capture, so changes to
+    /// RenderContext.SessionFrameHooks after that are picked up only together with a global hook change.
+    /// </summary>
     private void EnsureActiveHooksUpToDate()
     {
         var globalVersion = RenderSession.GlobalHooksVersion;
@@ -201,12 +362,14 @@ internal class RenderManager : MonoBehaviour
         _hasActiveHooksCached = _activeHooksCache.Count > 0;
     }
 
+    /// <summary>Returns the cached active hook list (session hooks first, then global hooks). The list is reused.</summary>
     private List<Action<FrameHookContext>> GetActiveFrameHooks()
     {
         EnsureActiveHooksUpToDate();
         return _activeHooksCache;
     }
 
+    /// <summary>Disposes the frame hook pipeline (ping-pong buffers) and clears the hook cache.</summary>
     private void ResetFrameHookState()
     {
         _frameHookPipeline?.Dispose();
@@ -216,46 +379,132 @@ internal class RenderManager : MonoBehaviour
         _hasActiveHooksCached = false;
     }
 
+    /// <summary>
+    /// Number of game frames offered for capture since capture started (OnPostFrame with a texture, after throttling).
+    /// The value before the increment is the render frame index of the current frame. Main thread only.
+    /// </summary>
     public long frameCountForVideo;
+
+    /// <summary>
+    /// Video frame index of the last captured frame (-1 before the first). A game frame is captured only when its video
+    /// frame index (render frame index × effective video FPS / RenderFPS, rounded down) is greater. Main thread only.
+    /// </summary>
     public long lastVideoFrameIndex = -1;
-    // long cannot be volatile: access via Volatile.Read/Write (written on main thread, read on render thread)
+
+    /// <summary>
+    /// Video frame index of the last capture request (-1 before the first). Written on the main Unity thread, read by the
+    /// render thread to know when every requested frame has been sent after endRequested.
+    /// </summary>
+    // long cannot be volatile: access via Volatile.Read/Write (written on main Unity thread, read on render thread)
     public long lastRequestedVideoFrameIndex = -1;
+
+    /// <summary>
+    /// Number of GPU readbacks that failed and were replaced by a black frame (shown by the debug monitor).
+    /// Incremented in the readback completion callback.
+    /// </summary>
     public int readbackFailureCount;
+
+    /// <summary>Number of frames on which the main Unity thread had to wait for the render thread (throttle loop entries).</summary>
     public int throttleCount;
+
+    /// <summary>True while the main Unity thread is inside the throttle wait of OnPostFrame.</summary>
     public bool isThrottling;
 
+    /// <summary>
+    /// One frame waiting in ImageQueue: either a native readback buffer (owned by ReadbackState until it is recycled)
+    /// or a managed buffer rented from ArrayPool&lt;byte&gt;.Shared (black frame for a failed readback).
+    /// The data is YUV 4:2:0 in the encoder's pixel format when IsColorConverted, RGBA otherwise.
+    /// </summary>
     internal struct CapturedFrame
     {
+        /// <summary>Start of the native frame data (ReadbackState.NativeBuffer); zero for a managed frame.</summary>
         public IntPtr NativePointer;
+
+        /// <summary>Number of valid bytes of the frame data.</summary>
         public int Length;
+
+        /// <summary>Managed frame data rented from ArrayPool&lt;byte&gt;.Shared (may be longer than Length); null for a native frame.</summary>
         public byte[]? ManagedBuffer; // Non-null if it's a managed buffer (e.g. black frame)
+
+        /// <summary>Readback state owning NativePointer; returned to the FrameReader pool after the frame is encoded or dropped.</summary>
         public ReadbackRequestState? ReadbackState; // Associated state to recycle
+
+        /// <summary>True when the GPU converted the frame to the encoder's YUV format; false for RGBA data.</summary>
         public bool IsColorConverted;
     }
 
     // Thread and Queue State
+
+    /// <summary>
+    /// Captured frames waiting for the render thread, keyed by video frame index. Readbacks may complete in any order;
+    /// the render thread takes them in index order (passCount). Every access locks the list itself.
+    /// Frames are added by readback completions (main Unity thread) and removed by the render thread, or released by the
+    /// cleanup in StopFFmpeg / RestoreRenderEnvironment.
+    /// </summary>
     internal SortedList<long, CapturedFrame> ImageQueue = new();
+
+    /// <summary>Set when a frame is added to ImageQueue or the end is requested; the render thread waits on it.</summary>
     internal AutoResetEvent FrameAvailableEvent = new(false);
-    // Set by the render thread each time it takes a frame from ImageQueue; the throttle loop waits on it.
+
+    /// <summary>Set by the render thread each time it takes a frame from ImageQueue; the throttle loop waits on it.</summary>
     internal AutoResetEvent FrameDequeuedEvent = new(false);
+
+    /// <summary>The render thread of the current render (background, AboveNormal priority); null before the first render.</summary>
     public Thread? RenderThread;
+
+    /// <summary>
+    /// Video frame index the render thread sends next. Reset by StartFFmpegThread before the thread starts; afterwards
+    /// read and written only by the render thread, under the ImageQueue lock.
+    /// </summary>
     public long passCount;
+
+    /// <summary>Set by StopFFmpeg: no more frames will be captured; the render thread drains the queue and stops.</summary>
     public volatile bool endRequested;
+
+    /// <summary>Set by the render thread after the output file was finished and the encoder released without an abort.</summary>
     public volatile bool endSuccessful;
+
+    /// <summary>
+    /// frameCount at which EndCondition first returned true; -1 until then. The render ends DelayAfterEnd seconds of
+    /// render time later.
+    /// </summary>
     public long endFrame = -1;
 
     // Private Instance Fields
+
+    /// <summary>Encoder of the current render; null when none runs. Cleared when the render thread releases it.</summary>
     private FFmpegNativeEncoder? _activeVideoFFmpeg;
+
+    /// <summary>
+    /// Every encoder created and not yet released, disposed by CleanUpActiveRender on exit. Locked on the list itself
+    /// (the render thread removes its encoder when it finishes).
+    /// </summary>
     private readonly List<FFmpegNativeEncoder> _allVideoFFmpegInstances = new();
+
+    /// <summary>The user's input offset (scrConductor.currentPreset.inputOffset), set to 0 during the render and restored afterwards.</summary>
     private int _originalInputOffset;
+
+    /// <summary>Debug monitor overlay object, created when the encoder starts and destroyed when the render ends.</summary>
     private GameObject? _debugMonitorObj;
+
+    /// <summary>ESC handler overlay object (cancels the render), created when the scene is set up and destroyed by StopFFmpeg.</summary>
     private GameObject? _escapeHandlerObj;
+
+    /// <summary>
+    /// Output file path of the current or last render. Set when the encoder starts; set to null when an aborted render's
+    /// file was deleted.
+    /// </summary>
     internal string? CurrentOutPath;
 
     // Output file of the current render that is not finished yet.
     // Set just before the encoder opens the file, cleared by the render thread after the encoder finished the file (End).
     // Only this file is deleted when a render is cancelled, fails or the game exits (DeleteIncompleteOutputFile).
     private string? _incompleteOutputPath;
+
+    /// <summary>
+    /// True from SetupGameScene until Update has set up the loaded game scene (or the render stops). While true, Update
+    /// hides the difficulty UI and waits for scnGame to finish loading.
+    /// </summary>
     private bool _renderSetup;
 
     private void Awake()
@@ -268,6 +517,10 @@ internal class RenderManager : MonoBehaviour
         CleanUpActiveRender();
     }
 
+    /// <summary>
+    /// Sets the stage to None. <paramref name="success"/> true clears the cancelled flag; false marks the render as
+    /// cancelled (unless it already failed). Called at every end path before StopFFmpeg.
+    /// </summary>
     public void ResetRenderState(bool success)
     {
         if (success) _isRenderCancelled = false;
@@ -275,6 +528,11 @@ internal class RenderManager : MonoBehaviour
         stage = RenderStage.None;
     }
 
+    /// <summary>
+    /// Emergency cleanup when the game quits or this object is destroyed: marks a running render as failed, releases
+    /// the audio, the frame hooks and every encoder, waits up to 200 ms for the render thread, and deletes the
+    /// unfinished output file. Does not restore the game scene or settings. Main thread.
+    /// </summary>
     public void CleanUpActiveRender()
     {
         if (stage != RenderStage.None)
@@ -346,8 +604,16 @@ internal class RenderManager : MonoBehaviour
         }
     }
 
+    /// <summary>
+    /// Main thread, every frame.
+    ///   1. While the game scene of a render loads: hides the difficulty UI of the press-to-start screen.
+    ///   2. Once scnGame has finished loading: sets up the scene for rendering and starts SetupPlay (stage OnScene).
+    ///   3. From the OnScene stage: fails the render when the render thread died, the level failed or the controller is
+    ///      gone; ends it successfully DelayAfterEnd seconds (render time) after EndCondition first returned true.
+    /// </summary>
     private void Update()
     {
+        // scrPressToStart reads lm.hideDifficultyUI to decide whether the difficulty UI is shown (scrPressToStart.cs).
         if (_renderSetup && ADOBase.lm)
         {
             ADOBase.lm.hideDifficultyUI = true;
@@ -356,18 +622,24 @@ internal class RenderManager : MonoBehaviour
         if (_renderSetup && scnGame.instance && !scnGame.instance.isLoading)
         {
             _renderSetup = false;
+            // scrCamera.Awake calls SetupRTCam(enable: true) when forceRTCam is set (scrCamera.cs), so the flag applies to
+            // the next scrCamera.Awake. scnGame also calls SetupRTCam(enable: true) when it starts playing (scnGame.cs).
             scrCamera.instance.forceRTCam = true;
                 
             if (!scrCamera.instance.gameObject.GetComponent<PostRenderHook>())
                 scrCamera.instance.gameObject.AddComponent<PostRenderHook>();
 
+            // The input offset shifts the song position (calibration_i = inputOffset / 1000 in scrConductor);
+            // the render runs with 0 so audio and visuals follow the level timing exactly. Restored by RestoreRenderEnvironment.
             _originalInputOffset = scrConductor.currentPreset.inputOffset;
             scrConductor.currentPreset.inputOffset = 0;
                 
+            // Autoplay; disableCongratsMessage clears the "congratulations" text shown on the win screen (scrController.cs).
             RDC.auto = RenderContext.Auto;
             AccessTools.Field(typeof(scrController), "disableCongratsMessage")
                 .SetValue(scrController.instance, true);
                 
+            // No-fail with an infinite hit margin, so a missed hit does not fail the level during the render.
             if (scrController.instance)
             {
                 scrController.instance.noFail = true;
@@ -384,6 +656,9 @@ internal class RenderManager : MonoBehaviour
                 DontDestroyOnLoad(_escapeHandlerObj);
             }
                 
+            // While non-zero, Unity advances Time.time by exactly this interval per frame regardless of real time,
+            // so the game simulation steps 1 / RenderFPS seconds per frame. Reset to 0 by RestoreRenderEnvironment.
+            // Reference: https://docs.unity3d.com/ScriptReference/Time-captureDeltaTime.html
             Time.captureDeltaTime = (float)(1 / Configuration.RenderFPS);
             scrController.instance!.StartCoroutine(SetupPlay());
         }
@@ -404,6 +679,8 @@ internal class RenderManager : MonoBehaviour
         }
         else if (RenderContext.EndCondition())
         {
+            // The first frame the end condition holds starts the DelayAfterEnd period; afterwards the end condition is
+            // still polled every frame, but endFrame is kept.
             if (endFrame == -1)
             {
                 endFrame = frameCount;
@@ -417,6 +694,9 @@ internal class RenderManager : MonoBehaviour
         }
     }
 
+    /// <summary>
+    /// Called by FirstUpdateHook before every other Update of the frame. Advances frameCount by one from the OnScene stage.
+    /// </summary>
     public void OnPreUpdate()
     {
         if (Instance.stage < RenderStage.OnScene) return;
@@ -428,6 +708,10 @@ internal class RenderManager : MonoBehaviour
     private List<scrFloor>? _holdFloorsSource;
     private int _holdFloorsSourceCount = -1;
 
+    /// <summary>
+    /// Called by PostRenderHook after every other LateUpdate of the frame, from the Load stage.
+    /// Hides the hold meshes when AdvancedConfig.NonTile is set, then runs RenderContext.OnLastUpdate.
+    /// </summary>
     public void OnLastUpdate()
     {
         if (Instance.stage < RenderStage.Load) return;
@@ -479,6 +763,15 @@ internal class RenderManager : MonoBehaviour
         return (int)Math.Min(MaxQueuedFrames, Math.Max(4, MaxQueuedBytes / frameBytes));
     }
 
+    /// <summary>
+    /// Called by PostRenderHook at the end of every frame (after rendering) with the frame texture. In the Render stage:
+    ///   1. Audio: updates the song voice, commits the audio commands of this frame, and deactivates the effect
+    ///      AudioSources that were mapped to mixer voices.
+    ///   2. Throttle: blocks while ImageQueue holds more than QueueFrameLimit frames (render thread behind).
+    ///   3. Capture: when this game frame starts a new video frame, runs the frame hooks and requests the GPU readback.
+    ///      With RenderFPS above the effective video FPS, only some game frames are captured.
+    /// </summary>
+    /// <param name="texture">Frame shown by the camera quad; null skips throttling and capture.</param>
     // ReSharper disable once Unity.IncorrectMethodSignature
     public void OnPostFrame(RenderTexture? texture)
     {
@@ -495,7 +788,7 @@ internal class RenderManager : MonoBehaviour
         if (!texture) return;
 
         // [Backpressure Throttling]
-        // The main thread waits while ImageQueue holds more than QueueFrameLimit frames. Only the render thread
+        // The main Unity thread waits while ImageQueue holds more than QueueFrameLimit frames. Only the render thread
         // removes frames, and it signals FrameDequeuedEvent for each one. The wait has a timeout so that the loop
         // re-checks the render thread state and pumps pending readback completions (see ThrottleWaitMilliseconds).
         isThrottling = false;
@@ -532,10 +825,13 @@ internal class RenderManager : MonoBehaviour
 
         var currentFrame = frameCountForVideo++;
             
+        // The video cannot have more frames per second than the game renders: effective video FPS = min(VideoFPS, RenderFPS).
         var renderFPS = Configuration.RenderFPS;
         var videoFps = Configuration.VideoFPS;
         var effectiveVideoFps = Math.Min(videoFps, renderFPS);
             
+        // Video frame that contains this game frame's time (currentFrame / renderFPS seconds), rounded down.
+        // Only the first game frame of each video frame is captured.
         var videoFrameIndex = (long)(currentFrame * effectiveVideoFps / renderFPS);
 
         if (videoFrameIndex > lastVideoFrameIndex)
@@ -562,6 +858,13 @@ internal class RenderManager : MonoBehaviour
         }
     }
 
+    /// <summary>
+    /// Handler of the render button in the level editor (added by scnEditorPatch).
+    /// When the level has no file path, scnEditor.TryQuitToMenu is called and no render starts.
+    /// Otherwise, after the editor's unsaved-changes prompt, removes scnEditor.TryApplicationQuit from
+    /// Application.wantsToQuit (it would block quitting with an unsaved-changes prompt; scnEditor registers it again
+    /// when the editor starts) and opens the render configuration window. Main thread.
+    /// </summary>
     public static void StartRender()
     {
         var targetMethod = typeof(scnEditor).GetMethod("TryApplicationQuit",
@@ -585,12 +888,18 @@ internal class RenderManager : MonoBehaviour
         });
     }
 
+    /// <summary>Creates the default output directory (GlobalSettings.EffectiveOutputDirectory) when it does not exist.</summary>
     public void SetupCaptureDirectory()
     {
         var renderDir = GlobalSettings.EffectiveOutputDirectory;
         FileUtil.CreateDirectory(renderDir);
     }
 
+    /// <summary>
+    /// Loads scnGame with levelPath as the only custom level (checkpoint 0, speed trial multiplier 1) and arms the
+    /// press-to-start skip and the scene setup in Update. Seeds UnityEngine.Random when AdvancedConfig.RandomSeed is set,
+    /// so random effects repeat between renders. Called by RenderSession.Start.
+    /// </summary>
     public void SetupGameScene()
     {
         GCS.customLevelPaths = new[] { levelPath };
@@ -605,8 +914,18 @@ internal class RenderManager : MonoBehaviour
         _renderSetup = true;
     }
 
+    /// <summary>
+    /// Coroutine started on scrController when the game scene is set up (stage OnScene).
+    /// Waits the countdown (real-time seconds), sets the time bases, starts the encoder, the render thread and the
+    /// frame reader, switches to the Render stage, starts the level without the press-to-start wait, and creates the
+    /// offline audio mixer and spectrum generator. Stops without starting when the render was aborted during the
+    /// countdown. On an encoder initialization error, the render fails, the environment is restored and an error
+    /// dialog returns to the editor.
+    /// </summary>
     private IEnumerator SetupPlay()
     {
+        // The audio sample rate must be one the audio codec paired with the video codec supports
+        // (CodecUtil.AudioCodecMatch, CodecUtil.AvailableSampleRate); otherwise 48000 Hz is used.
         if (Configuration.AudioConfig.RenderAudio)
         {
             if (!CodecUtil.AvailableSampleRate[CodecUtil.AudioCodecMatch[Configuration.VideoConfig.Codec]].Contains(Configuration.AudioConfig.AudioSampleRate)) 
@@ -624,6 +943,8 @@ internal class RenderManager : MonoBehaviour
         frameCount = 0; framesSent = 0;
         _renderStopwatch.Restart();
             
+        // Clock values at the start of capture. The time patches are not active yet (stage OnScene), so these are
+        // Unity's own values; from the Render stage the patched clocks continue from them at frameCount / RenderFPS.
         timeBase = Time.timeAsDouble;
         unscaledTimeBase = Time.unscaledTimeAsDouble;
         dspTimeBase = AudioSettings.dspTime;
@@ -635,6 +956,7 @@ internal class RenderManager : MonoBehaviour
         _frameHookPipeline = new FrameHookPipeline();
         _cachedGlobalHooksVersion = -1;
         EnsureActiveHooksUpToDate();
+        // The frame reader converts on the GPU to the pixel format of the encoder that was actually opened.
         try
         {
             StartFFmpegThread();
@@ -663,6 +985,7 @@ internal class RenderManager : MonoBehaviour
         }
 
         Instance.stage = RenderStage.Render;
+        // levelWasSkipped ends the press-to-start wait loop of scrController (scrController.cs, WaitForStartCo).
         scrController.instance.paused = scrController.instance.audioPaused = false;
         scrController.instance.levelWasSkipped = true;
             
@@ -681,10 +1004,18 @@ internal class RenderManager : MonoBehaviour
             AudioSpectrumGenerator.Initialize(scrConductor.instance.song.clip, AudioMixer);
         }
             
+        // The song is played by the offline mixer only: the clip is removed from the game's song AudioSource so Unity
+        // does not play it.
         scrConductor.instance.song.clip = null;
         scrConductor.instance.song.time = -1000;
     }
 
+    /// <summary>
+    /// Resets the queue and render thread state, opens the encoder on the output file (RenderContext.OutputPath, or
+    /// "yyyy-MM-dd HH-mm-ss.ext" in the output directory with the configured extension), and starts the render thread.
+    /// The output path is registered as incomplete before the encoder opens the file.
+    /// </summary>
+    /// <exception cref="Exception">The encoder could not be created or started; it is disposed before the exception is rethrown.</exception>
     private void StartFFmpegThread()
     {
         if (!_debugMonitorObj)
@@ -770,6 +1101,7 @@ internal class RenderManager : MonoBehaviour
             throw;
         }
 
+        // Background thread: it does not keep the process alive when the game quits.
         var encoder = videoFFmpeg;
         RenderThread = new Thread(() => RunRenderThread(encoder))
         {
@@ -858,8 +1190,10 @@ internal class RenderManager : MonoBehaviour
     }
 
     /// <summary>
-    /// Removes the frame whose key equals passCount from ImageQueue and advances passCount.
-    /// Before the Render stage, passCount jumps to the first queued key (the first captured frame index is not 0).
+    /// Removes the frame whose key equals passCount from ImageQueue and advances passCount. Render thread.
+    /// While the stage is below Render, passCount jumps forward to the first queued key when that key is greater:
+    /// frames are only captured in the Render stage, so this happens after the stage was set back to None at the end
+    /// of the render while the thread drains the queue, and a frame whose readback has not arrived yet is skipped.
     /// Returns false when the queue is empty or the next frame has not arrived yet.
     /// </summary>
     private bool TryDequeueNextFrame(out CapturedFrame frame)
@@ -886,7 +1220,7 @@ internal class RenderManager : MonoBehaviour
 
     /// <summary>
     /// Sends one captured frame to the encoder and releases its buffer (managed: ArrayPool, native: readback state).
-    /// A frame without data is skipped.
+    /// A frame without data is skipped (not counted in framesSent). Render thread.
     /// </summary>
     private void SendVideoFrame(FFmpegNativeEncoder videoFFmpeg, in CapturedFrame frame)
     {
@@ -914,8 +1248,11 @@ internal class RenderManager : MonoBehaviour
 
     /// <summary>
     /// Mixes the audio of the frame that was just sent (index passCount - 1) and writes it to the encoder.
-    /// Does nothing when audio rendering is off.
+    /// The sample count per frame comes from SyncCalculator (sample rate / effective video FPS, with the remainder
+    /// carried to later frames). Mixing waits until the main Unity thread has committed the audio commands up to that time.
+    /// Does nothing when audio rendering is off. Render thread.
     /// </summary>
+    /// <exception cref="OperationCanceledException">The mixer was cancelled (render aborted) while waiting.</exception>
     private void WriteAudioForFrame(FFmpegNativeEncoder videoFFmpeg)
     {
         if (!Configuration.AudioConfig.RenderAudio || SyncCalculator is not { } syncCalculator) return;
@@ -945,6 +1282,7 @@ internal class RenderManager : MonoBehaviour
         return endRequested && passCount > Volatile.Read(ref lastRequestedVideoFrameIndex);
     }
 
+    /// <summary>Removes the encoder from the cleanup list and clears _activeVideoFFmpeg. Called by the render thread when it finishes.</summary>
     private void UnregisterEncoder(FFmpegNativeEncoder videoFFmpeg)
     {
         lock (_allVideoFFmpegInstances)
@@ -954,6 +1292,11 @@ internal class RenderManager : MonoBehaviour
         _activeVideoFFmpeg = null;
     }
 
+    /// <summary>
+    /// Stops the render without finishing the file (cancelled, or failed when MarkFailed was called first), deletes
+    /// the unfinished file, reports the result through OnComplete, restores the environment and returns to the editor.
+    /// Called by the ESC handler and on failures. Main thread.
+    /// </summary>
     public void CancelRender()
     {
         ResetRenderState(success: false);
@@ -962,6 +1305,15 @@ internal class RenderManager : MonoBehaviour
         EndRender();
     }
 
+    /// <summary>
+    /// Requests the end of encoding. Main thread.
+    /// <paramref name="success"/> true: completes the audio commands and starts StopRenderCoroutine, which waits for
+    /// the render thread to send the remaining frames and finish the file.
+    /// <paramref name="success"/> false: marks the render as cancelled (unless failed), cancels the audio waits, waits up
+    /// to 2 s for the render thread, disposes the encoder, releases the queued frames, the frame reader, the hooks and
+    /// the debug monitor, restores the camera and no-fail flags, deletes the unfinished file and calls OnComplete with
+    /// a failure result. Does not restore time, input offset or the scene (EndRender / RestoreRenderEnvironment do).
+    /// </summary>
     private void StopFFmpeg(bool success)
     {
         endRequested = true;
@@ -993,7 +1345,8 @@ internal class RenderManager : MonoBehaviour
                 RenderThread.Join(2000);
             }
 
-            // 2. After ensuring thread termination, safely release FFmpeg native encoder resources
+            // 2. Release the encoder. The render thread normally released it already (_activeVideoFFmpeg is then null).
+            //    When the thread is still running after the 2 s wait, the encoder is disposed while that thread may still use it.
             if (_activeVideoFFmpeg != null)
             {
                 _activeVideoFFmpeg.Dispose();
@@ -1055,6 +1408,11 @@ internal class RenderManager : MonoBehaviour
         }
     }
 
+    /// <summary>
+    /// Successful end: waits (one check per frame) until the render thread reports endSuccessful or has died.
+    /// On success calls OnComplete with a success result and EndRender; when the thread died without finishing
+    /// the file, the render fails and is cancelled (file deleted).
+    /// </summary>
     private IEnumerator StopRenderCoroutine()
     {
         yield return new WaitUntil(() => endSuccessful || RenderThread is not { IsAlive: true });
@@ -1071,6 +1429,7 @@ internal class RenderManager : MonoBehaviour
         EndRender();
     }
 
+    /// <summary>Restores the render environment and loads the level editor (scnEditor).</summary>
     private void EndRender()
     {
         RestoreRenderEnvironment();
@@ -1079,7 +1438,11 @@ internal class RenderManager : MonoBehaviour
         Cursor.visible = true;
     }
 
-    // Undoes what the render setup changed (time, input offset, auto, queues, session hooks), without leaving the scene.
+    /// <summary>
+    /// Undoes what the render setup changed (time scale and capture delta time, input offset, autoplay, custom level
+    /// paths, queued frames, frame reader, frame hooks, audio mixer and spectrum, RenderContext options), without
+    /// leaving the scene.
+    /// </summary>
     private void RestoreRenderEnvironment()
     {
         Time.timeScale = 1f;
@@ -1122,6 +1485,10 @@ internal class RenderManager : MonoBehaviour
             
     }
 
+    /// <summary>
+    /// Stops the render stopwatch and creates the result: frames sent, video duration (frames / effective video FPS),
+    /// wall-clock render time, and the output path and file size on success.
+    /// </summary>
     private RenderResult BuildResult(bool success, string? errorMessage = null)
     {
         _renderStopwatch.Stop();
@@ -1133,6 +1500,7 @@ internal class RenderManager : MonoBehaviour
             : RenderResult.CreateFailure(errorMessage, sent, effectiveFps, _renderStopwatch.Elapsed);
     }
 
+    /// <summary>Invokes RenderContext.OnComplete; an exception from the callback is logged.</summary>
     private static void TriggerOnComplete(RenderResult result)
     {
         try
@@ -1145,6 +1513,7 @@ internal class RenderManager : MonoBehaviour
         }
     }
     
+    /// <summary>Invokes RenderContext.OnLastUpdate; an exception from the callback is logged.</summary>
     private static void TriggerOnLastUpdate()
     {
         try

Data/Codec.cs

@@ -4,14 +4,22 @@ using FFmpeg.AutoGen;
 
 namespace ADOFAIRenderer.Data;
 
+/// <summary>
+/// Video codec of the output. The encoder implementation (hardware or software) is chosen at run time from the
+/// encoders available for the codec (VideoEncoder, GPUUtil.GetPrioritizedEncoders).
+/// Values: <c>H264</c> (H.264 / AVC), <c>H265</c> (H.265 / HEVC), <c>VP9</c>, <c>AV1</c>, <c>VVC</c> (H.266).
+/// The audio codec paired with each value is given by CodecUtil.AudioCodecMatch.
+/// </summary>
 [SuppressMessage("ReSharper", "InconsistentNaming")]
 public enum Codec
 {
     H264, H265, VP9, AV1, VVC
 }
 
+/// <summary>Audio codec choice and supported sample rates per video codec.</summary>
 internal static class CodecUtil
 {
+    /// <summary>Audio codec encoded together with each video codec (AAC for H.264/H.265, Opus for the others).</summary>
     public static readonly Dictionary<Codec, AVCodecID> AudioCodecMatch = new()
     {
         [Codec.H264] = AVCodecID.AV_CODEC_ID_AAC,
@@ -21,6 +29,10 @@ internal static class CodecUtil
         [Codec.VVC] = AVCodecID.AV_CODEC_ID_OPUS
     };
 
+    /// <summary>
+    /// Output sample rates (Hz) the mod allows per audio codec. RenderManager.SetupPlay replaces a configured rate that
+    /// is not in the list with 48000 Hz.
+    /// </summary>
     public static readonly Dictionary<AVCodecID, List<int>> AvailableSampleRate = new()
     {
         [AVCodecID.AV_CODEC_ID_AAC] = new List<int> { 44100, 48000, 96000 },

Data/ColorJsonConverter.cs

@@ -10,13 +10,20 @@ namespace ADOFAIRenderer.Data;
 /// Converts Unity <see cref="Color"/> and nullable <see cref="Color"/> to and from hex string (#RRGGBBAA).
 /// Pure C# implementation to completely avoid Unity internal native ECalls (such as Color.linear or ColorUtility.TryParseHtmlString).
 /// </summary>
+/// <remarks>
+/// Reading accepts "#RRGGBB" (alpha 1), "#RRGGBBAA" (the '#' is optional), an object {"r","g","b","a"} with 0–1 floats
+/// (missing r/g/b = 0, missing a = 1), or null. Invalid or unsupported input reads as null for Color? and as
+/// default(Color) (all components 0) for Color; no exception is thrown for an unparsable string.
+/// </remarks>
 public class ColorJsonConverter : JsonConverter
 {
+    /// <summary>True for <see cref="Color"/> and <see cref="Nullable{Color}"/>.</summary>
     public override bool CanConvert(Type objectType)
     {
         return objectType == typeof(Color) || objectType == typeof(Color?);
     }
 
+    /// <summary>Writes the color as "#RRGGBBAA" (see <see cref="ToHex"/>), or a JSON null for a null value.</summary>
     public override void WriteJson(JsonWriter writer, object? value, JsonSerializer serializer)
     {
         if (value == null)
@@ -29,6 +36,7 @@ public class ColorJsonConverter : JsonConverter
         writer.WriteValue(ToHex(color));
     }
 
+    /// <summary>Reads a color in one of the accepted forms (see the class remarks).</summary>
     public override object? ReadJson(JsonReader reader, Type objectType, object? existingValue, JsonSerializer serializer)
     {
         bool isNullable = Nullable.GetUnderlyingType(objectType) != null || !objectType.IsValueType;
@@ -62,6 +70,10 @@ public class ColorJsonConverter : JsonConverter
         return isNullable ? null : (object)default(Color);
     }
 
+    /// <summary>
+    /// Formats the color as "#RRGGBBAA" with uppercase hex digits. Each component is scaled to 0–255, rounded and clamped.
+    /// The components are written as stored (no gamma conversion).
+    /// </summary>
     public static string ToHex(Color color)
     {
         byte r = (byte)Math.Clamp((int)Math.Round(color.r * 255f), 0, 255);
@@ -71,6 +83,12 @@ public class ColorJsonConverter : JsonConverter
         return $"#{r:X2}{g:X2}{b:X2}{a:X2}";
     }
 
+    /// <summary>
+    /// Parses "RRGGBB" or "RRGGBBAA" (optional leading '#', surrounding white space ignored, case-insensitive).
+    /// </summary>
+    /// <param name="hex">Text to parse.</param>
+    /// <param name="color">Parsed color (components / 255; alpha 1 for the 6-digit form), or default when parsing fails.</param>
+    /// <returns>True when the text was parsed.</returns>
     public static bool TryParseHex(string? hex, out Color color)
     {
         color = default;

Data/RateControlMode.cs

@@ -2,10 +2,19 @@
 
 namespace ADOFAIRenderer.Data;
 
+/// <summary>Video bitrate control mode (see VideoEncodingConfig and FFmpegNativeEncoder.ApplyQualitySettings).</summary>
 [SuppressMessage("ReSharper", "InconsistentNaming")]
 public enum RateControlMode
 {
+    /// <summary>Constant bitrate at VideoEncodingConfig.Bitrate (kbps).</summary>
     CBR,
+
+    /// <summary>
+    /// Variable bitrate averaging VideoEncodingConfig.Bitrate (kbps), peaking at MaxBitrate (kbps) when it is larger,
+    /// otherwise at 1.5 × Bitrate.
+    /// </summary>
     VBR,
+
+    /// <summary>Constant quality with VideoEncodingConfig.QP (lower is better; range depends on the encoder).</summary>
     CQP
 }

Data/RenderConfig.cs

@@ -4,22 +4,50 @@ using UnityEngine;
 
 namespace ADOFAIRenderer.Data;
 
+/// <summary>
+/// Settings of one render: resolution, frame rates, encoding and advanced options. Serialized to JSON in the preset
+/// files (PresetManager). <see cref="ADOFAIRenderer.API.RenderSession.Start"/> renders with a copy (<see cref="Clone"/>).
+/// </summary>
 [SuppressMessage("ReSharper", "RedundantDefaultMemberInitializer")]
 public class RenderConfig
 {
+    /// <summary>
+    /// Game frames simulated per second of render time (the game clock advances 1 / RenderFPS seconds per frame).
+    /// Values above <see cref="VideoFPS"/> render extra frames between video frames, which are not captured
+    /// (the game state then advances in smaller time steps).
+    /// </summary>
     public double RenderFPS { get; set; }
+
+    /// <summary>
+    /// Frame rate of the output video. The effective rate is min(VideoFPS, RenderFPS).
+    /// </summary>
     public double VideoFPS { get; set; }
 
+    /// <summary>Width of the rendered frames and the output video in pixels (also reported by the Screen.width patch).</summary>
     public int RenderWidth { get; set; }
+
+    /// <summary>Height of the rendered frames and the output video in pixels (also reported by the Screen.height patch).</summary>
     public int RenderHeight { get; set; }
         
+    /// <summary>Video encoder settings.</summary>
     public VideoEncodingConfig VideoConfig { get; set; } = new();
+
+    /// <summary>Audio rendering and encoder settings.</summary>
     public AudioEncodingConfig AudioConfig { get; set; } = new();
+
+    /// <summary>Advanced options (random seed, spectrum processing, tile hiding, container, planet colors).</summary>
     public AdvancedConfig AdvancedConfig { get; set; } = new();
 
+    /// <summary>Seconds of render time recorded after the end condition first holds (default 15).</summary>
     public double DelayAfterEnd { get; set; } = 15;
+
+    /// <summary>Whether the judgement texts (hit accuracy texts) are shown during the render (scrHitTextManagerPatch). Default false.</summary>
     public bool ShowJudgementText { get; set; } = false;
 
+    /// <summary>
+    /// Copies every value of <paramref name="source"/> into this object; the nested configs are copied value by value
+    /// into the existing nested objects. Does nothing when <paramref name="source"/> is null.
+    /// </summary>
     public void CopyFrom(RenderConfig? source)
     {
         if (source == null) return;
@@ -35,6 +63,7 @@ public class RenderConfig
         AdvancedConfig.CopyFrom(source.AdvancedConfig);
     }
 
+    /// <summary>Returns a deep copy (nested configs are new objects).</summary>
     public RenderConfig Clone()
     {
         var clone = new RenderConfig();
@@ -43,23 +72,48 @@ public class RenderConfig
     }
 }
 
+/// <summary>Advanced render options.</summary>
 [SuppressMessage("ReSharper", "RedundantDefaultMemberInitializer")]
 public class AdvancedConfig
 {
+    /// <summary>
+    /// Seed for UnityEngine.Random set before the game scene loads, so random visual effects repeat between renders;
+    /// null leaves the random state unchanged.
+    /// </summary>
     public int? RandomSeed { get; set; } = null;
+
+    /// <summary>
+    /// When true, AudioSource.GetSpectrumData is answered from the offline song audio at the render time
+    /// (AudioSpectrumGenerator), so audio-reactive visuals follow the rendered audio. Default true.
+    /// </summary>
     public bool ProcessAudio { get; set; } = true;
+
+    /// <summary>
+    /// When true, the level's floor tiles (including hold meshes and the portal particles of the level's floors) and the
+    /// planets are hidden during the render, so only the background and decorations remain (scnGamePatch, scrFloorPatch,
+    /// RenderManager.OnLastUpdate). Default false.
+    /// </summary>
     public bool NonTile { get; set; } = false;
+
+    /// <summary>File extension of the default output file name, without the dot (e.g. "mkv", "mp4"); selects the container.</summary>
     public string FileExtension { get; set; } = "mkv";
 
+    /// <summary>Color of the fire (red) planet during the render; null keeps the user's setting. Serialized as "#RRGGBBAA".</summary>
     [JsonConverter(typeof(ColorJsonConverter))]
     public Color? firePlanetColor = null;
 
+    /// <summary>Color of the ice (blue) planet during the render; null keeps the user's setting. Serialized as "#RRGGBBAA".</summary>
     [JsonConverter(typeof(ColorJsonConverter))]
     public Color? icePlanetColor = null;
 
+    /// <summary>
+    /// Color of the third (wind, planetGreen) planet during the render (PlanetarySystemPatch); null keeps the game's color.
+    /// Serialized as "#RRGGBBAA".
+    /// </summary>
     [JsonConverter(typeof(ColorJsonConverter))]
     public Color? windPlanetColor = null;
 
+    /// <summary>Copies every value of <paramref name="source"/>; does nothing when it is null.</summary>
     public void CopyFrom(AdvancedConfig? source)
     {
         if (source == null) return;
@@ -72,6 +126,7 @@ public class AdvancedConfig
         windPlanetColor = source.windPlanetColor;
     }
 
+    /// <summary>Returns a copy of this object.</summary>
     public AdvancedConfig Clone()
     {
         var clone = new AdvancedConfig();
@@ -80,18 +135,35 @@ public class AdvancedConfig
     }
 }
 
+/// <summary>Video encoder settings (passed to FFmpegNativeEncoder.EncoderSettings).</summary>
 public class VideoEncodingConfig
 {
+    /// <summary>Video codec (default H.264). Also selects the audio codec (CodecUtil.AudioCodecMatch).</summary>
     public Codec Codec { get; set; } = Codec.H264;
+
+    /// <summary>Bitrate control mode (default CBR).</summary>
     public RateControlMode RateControlMode { get; set; } = RateControlMode.CBR;
         
+    /// <summary>Target video bitrate in kbps for CBR and VBR (default 30000 = 30 Mbps).</summary>
     public int Bitrate { get; set; } = 30000;
+
+    /// <summary>Peak video bitrate in kbps for VBR, used when larger than Bitrate (otherwise 1.5 × Bitrate). Default 50000.</summary>
     public int MaxBitrate { get; set; } = 50000;
+
+    /// <summary>
+    /// Quality value for CQP: lower is higher quality. Clamped to the range of the selected encoder; a negative value
+    /// selects 18. Default 18.
+    /// </summary>
     // ReSharper disable once InconsistentNaming
     public int QP { get; set; } = 18;
+
+    /// <summary>Keyframe interval in seconds (GOP length = round(effective video FPS × interval) frames, at least 1). Default 2.</summary>
     public double KeyframeInterval { get; set; } = 2.0;
+
+    /// <summary>When true, only software (CPU) encoders are tried; hardware encoders are skipped.</summary>
     public bool ForceSoftwareEncoder { get; set; }
 
+    /// <summary>Copies every value of <paramref name="source"/>; does nothing when it is null.</summary>
     public void CopyFrom(VideoEncodingConfig? source)
     {
         if (source == null) return;
@@ -104,6 +176,7 @@ public class VideoEncodingConfig
         ForceSoftwareEncoder = source.ForceSoftwareEncoder;
     }
 
+    /// <summary>Returns a copy of this object.</summary>
     public VideoEncodingConfig Clone()
     {
         var clone = new VideoEncodingConfig();
@@ -112,32 +185,44 @@ public class VideoEncodingConfig
     }
 }
 
+/// <summary>
+/// Audio rendering and encoder settings. Non-positive values of the numeric settings read back as their defaults
+/// (48000 Hz, 2 channels, 256000 bps).
+/// </summary>
 public class AudioEncodingConfig
 {
     private int _audioSampleRate = 48000;
     private int _audioChannels = 2;
     private int _audioBitrate = 256000;
 
+    /// <summary>When true, the song and sound effects are mixed offline and encoded as an audio stream. Default true.</summary>
     public bool RenderAudio { get; set; } = true;
 
+    /// <summary>
+    /// Output sample rate in Hz (default 48000). A rate the audio codec does not support in the mod
+    /// (CodecUtil.AvailableSampleRate) is replaced with 48000 when the render starts.
+    /// </summary>
     public int AudioSampleRate
     {
         get => _audioSampleRate <= 0 ? 48000 : _audioSampleRate;
         set => _audioSampleRate = value <= 0 ? 48000 : value;
     }
 
+    /// <summary>Number of output audio channels (default 2).</summary>
     public int AudioChannels
     {
         get => _audioChannels <= 0 ? 2 : _audioChannels;
         set => _audioChannels = value <= 0 ? 2 : value;
     }
 
+    /// <summary>Audio bitrate in bits per second (default 256000 = 256 kbps). Unit differs from the video bitrate (kbps).</summary>
     public int AudioBitrate
     {
         get => _audioBitrate <= 0 ? 256000 : _audioBitrate;
         set => _audioBitrate = value <= 0 ? 256000 : value;
     }
 
+    /// <summary>Copies every value of <paramref name="source"/>; does nothing when it is null.</summary>
     public void CopyFrom(AudioEncodingConfig? source)
     {
         if (source == null) return;
@@ -147,6 +232,7 @@ public class AudioEncodingConfig
         AudioBitrate = source.AudioBitrate;
     }
 
+    /// <summary>Returns a copy of this object.</summary>
     public AudioEncodingConfig Clone()
     {
         var clone = new AudioEncodingConfig();

Localization/LocalizationManager.cs

@@ -9,29 +9,49 @@ namespace ADOFAIRenderer.Localization;
 
 /// <summary>
 /// Provides access to localized strings and handles language synchronization with the game.
+/// <para>
+/// Locale files are flat JSON objects (<c>"key": "text"</c>) under <c>Localization/Locale/</c>, embedded in the mod
+/// assembly as resources; the file name without extension is the locale code (<c>en.json</c> -> "en").
+/// The active locale follows the game language: <c>LanguageSyncPatch</c> calls <see cref="SetLanguage"/> after the game's
+/// <c>RDString.Setup</c> and <c>RDString.ChangeLanguage</c>. Only Korean maps to its own locale ("ko"); every other
+/// language uses English ("en").
+/// </para>
+/// <para>
+/// Lookup order in <see cref="Get(string)"/>: active locale, then English, then the key itself.
+/// Intended for the main Unity thread; the dictionaries are filled once during initialization and only read afterwards.
+/// </para>
 /// </summary>
 internal static class LocalizationManager
 {
+    /// <summary>Loaded locales: locale code (case-insensitive) -> key -> text. Keys are case-sensitive.</summary>
     private static readonly Dictionary<string, Dictionary<string, string>> Locales = new(StringComparer.OrdinalIgnoreCase);
+    /// <summary>Locale used when the language has no locale file and for keys missing in the active locale.</summary>
     private static readonly string FallbackLocaleCode = "en";
 
     /// <summary>
     /// Event triggered when the active language changes.
+    /// Raised by <see cref="SetLanguage"/> with <c>notify: true</c> when the language or the resolved locale differs from
+    /// the current one; the argument is the new game language. Exceptions from handlers are caught and logged
+    /// (an exception stops the remaining handlers of that invocation).
     /// </summary>
     public static event Action<SystemLanguage>? OnLanguageChanged;
 
     /// <summary>
-    /// Currently active SystemLanguage.
+    /// Currently active SystemLanguage: the game language as passed to <see cref="SetLanguage"/>, also when it has no
+    /// locale file of its own (e.g. Japanese, which displays English text).
     /// </summary>
     public static SystemLanguage CurrentLanguage { get; private set; } = SystemLanguage.English;
 
     /// <summary>
-    /// Currently active locale code (e.g. "en", "ko").
+    /// Currently active locale code (e.g. "en", "ko"): the locale whose strings <see cref="Get(string)"/> returns first.
+    /// Always a loaded locale or the fallback "en".
     /// </summary>
     public static string CurrentLocaleCode { get; private set; } = "en";
 
+    /// <summary>Set by the first <see cref="Initialize"/> call; later calls return immediately.</summary>
     private static bool _initialized;
 
+    /// <summary>Initializes on first access to any member, so lookups work before <c>RenderMod</c> calls <see cref="Initialize"/>.</summary>
     static LocalizationManager()
     {
         Initialize();
@@ -39,6 +59,8 @@ internal static class LocalizationManager
 
     /// <summary>
     /// Initializes the localization system and loads embedded language dictionaries.
+    /// Runs once; further calls do nothing. Selects the initial language without raising
+    /// <see cref="OnLanguageChanged"/>.
     /// </summary>
     public static void Initialize()
     {
@@ -47,19 +69,26 @@ internal static class LocalizationManager
 
         LoadEmbeddedLocales();
 
-        // Detect initial language from game settings
+        // Detect initial language from game settings.
+        // At mod initialization RDString.Setup has usually not run yet, so this reads the field's initial value
+        // (English); LanguageSyncPatch applies the real language when the game calls RDString.Setup.
         var initialLang = DetectGameLanguage();
         SetLanguage(initialLang, notify: false);
 
         LogMsg($"[Localization] Initialized. Active language: {CurrentLanguage} ({CurrentLocaleCode})");
     }
 
+    /// <summary>
+    /// Logs through the MelonLoader logger of the mod, or to the console when that logger is not available
+    /// (e.g. when this class is used outside the running mod).
+    /// </summary>
     private static void LogMsg(string msg)
     {
         try { Melon<RenderMod>.Logger.Msg(msg); }
         catch { Console.WriteLine(msg); }
     }
 
+    /// <summary>Error counterpart of <see cref="LogMsg"/>; falls back to standard error.</summary>
     private static void LogError(string msg)
     {
         try { Melon<RenderMod>.Logger.Error(msg); }
@@ -68,6 +97,9 @@ internal static class LocalizationManager
 
     /// <summary>
     /// Loads all *.json locale files embedded in this assembly.
+    /// A resource is used when its name ends with ".json" and contains "Localization.Locale" (the manifest name built
+    /// from the folder path, see the EmbeddedResource item in the .csproj). A file that fails to read or parse is
+    /// logged and skipped; a later resource with the same locale code replaces an earlier one.
     /// </summary>
     private static void LoadEmbeddedLocales()
     {
@@ -109,7 +141,13 @@ internal static class LocalizationManager
 
     /// <summary>
     /// Sets the active language and notifies subscribers if changed.
+    /// The locale is chosen by <see cref="LanguageToLocaleCode"/>; when that locale is not loaded, "en" is used.
     /// </summary>
+    /// <param name="language">Game language (as used by <c>RDString.language</c>).</param>
+    /// <param name="notify">
+    /// Whether to raise <see cref="OnLanguageChanged"/> when the language or locale changes; <c>false</c> is used for
+    /// the initial selection.
+    /// </param>
     public static void SetLanguage(SystemLanguage language, bool notify = true)
     {
         var localeCode = LanguageToLocaleCode(language);
@@ -140,7 +178,10 @@ internal static class LocalizationManager
 
     /// <summary>
     /// Retrieves a localized string for the specified key.
+    /// Order: active locale, then English, then the key itself (so a missing key is visible in the UI).
     /// </summary>
+    /// <param name="key">Localization key, e.g. <c>"ui.render_config.window_title"</c>; case-sensitive.</param>
+    /// <returns>The localized text, the key when no locale has it, or an empty string for a null/empty key.</returns>
     public static string Get(string key)
     {
         if (string.IsNullOrEmpty(key)) return string.Empty;
@@ -166,7 +207,12 @@ internal static class LocalizationManager
 
     /// <summary>
     /// Retrieves a formatted localized string.
+    /// The text from <see cref="Get(string)"/> is used as a <see cref="string.Format(string, object[])"/> template
+    /// (<c>{0}</c>, <c>{1}</c>, ...), formatted with the current culture. When the template does not match the
+    /// arguments (<see cref="FormatException"/>), the unformatted template is returned.
     /// </summary>
+    /// <param name="key">Localization key.</param>
+    /// <param name="args">Format arguments; with none, the template is returned as is.</param>
     public static string Get(string key, params object[] args)
     {
         var template = Get(key);
@@ -184,6 +230,7 @@ internal static class LocalizationManager
 
     /// <summary>
     /// Maps Unity's SystemLanguage enum to an internal locale code.
+    /// Korean -> "ko"; every other language -> "en". A new locale file also needs an entry here.
     /// </summary>
     private static string LanguageToLocaleCode(SystemLanguage language)
     {
@@ -196,19 +243,22 @@ internal static class LocalizationManager
 
     /// <summary>
     /// Attempts to read the game's current language from RDString or Persistence.
+    /// Falls back to English when both reads throw.
     /// </summary>
     private static SystemLanguage DetectGameLanguage()
     {
         try
         {
-            // First attempt: RDString.language
+            // First attempt: RDString.language, a public static field of the game (initial value English,
+            // assigned from Persistence.language in RDString.Setup)
             return RDString.language;
         }
         catch
         {
             try
             {
-                // Fallback attempt: Persistence.language
+                // Fallback attempt: Persistence.language, the saved "language" preference (defaults to
+                // Application.systemLanguage)
                 return Persistence.language;
             }
             catch
@@ -221,6 +271,7 @@ internal static class LocalizationManager
 
 /// <summary>
 /// Convenient shorthand alias for <see cref="LocalizationManager"/>.
+/// Every member forwards to the member of the same name in <see cref="LocalizationManager"/>.
 /// </summary>
 // ReSharper disable once InconsistentNaming
 internal static class I18n

Patch/Engine/AsyncInputPatches.cs

@@ -3,10 +3,31 @@ using HarmonyLib;
 
 namespace ADOFAIRenderer.Patch.Engine;
 
+/// <summary>
+/// Makes the async input clock offset follow the render clock immediately.
+/// <para>
+/// Patched member: <c>AsyncInputUtils.UpdateOffsetTime(long fixDivider = 1)</c>. The async input system maps wall-clock ticks
+/// (<c>AsyncInputManager.currFrameTick</c> = <c>DateTime.Now.Ticks</c>, 100 ns units) to conductor time with
+/// <c>AsyncInputManager.offsetTick</c> = currFrameTick - <c>scrConductor.dspTime</c> * 10^7. With <c>fixDivider</c> 1 the
+/// offset is set directly; otherwise it moves by 1 / fixDivider of the difference per call. <c>scrConductor</c> calls it every
+/// frame with divider 100 (damped); <c>scrController</c> calls it with divider 1.
+/// </para>
+/// <para>
+/// Active while <see cref="RenderManager.IsActive"/> (stage &gt;= OnScene). From stage Render the conductor time follows the
+/// patched <c>AudioSettings.dspTime</c> (offline render clock, a fixed step per frame independent of wall-clock time), so the
+/// difference changes every frame; the damped update would lag behind it. The prefix always applies the divider-1 update.
+/// </para>
+/// <para>Reference: https://learn.microsoft.com/en-us/dotnet/api/system.datetime.ticks</para>
+/// </summary>
 [HarmonyPatch(typeof(AsyncInputUtils), "UpdateOffsetTime")]
 // ReSharper disable once InconsistentNaming
 public static class AsyncInputPatches
 {
+    /// <summary>
+    /// Prefix of <c>AsyncInputUtils.UpdateOffsetTime</c>. While rendering, sets <c>offsetTick</c> to
+    /// currFrameTick - dspTime * 10^7 (10^7 = 100 ns ticks per second) and <c>offsetTickUpdated</c> to true, for any divider.
+    /// </summary>
+    /// <returns>True to run the original method (not rendering); false to skip it (rendering).</returns>
     [HarmonyPrefix]
     // ReSharper disable once InconsistentNaming
     public static bool Prefix()

Patch/Engine/AudioPatches.cs

@@ -18,6 +18,7 @@ namespace ADOFAIRenderer.Patch.Engine;
 [HarmonyPatch(typeof(AudioManager), nameof(AudioManager.FindOrLoadAudioClipExternal))]
 public static class AudioManagerFindOrLoadAudioClipExternalPatch
 {
+    /// <summary>Records <paramref name="path"/> in <see cref="AudioClipPaths"/> when its audioLib key is not loaded yet. Runs the original always.</summary>
     [HarmonyPrefix]
     // ReSharper disable once InconsistentNaming
     public static void Prefix(AudioManager __instance, string path)
@@ -28,20 +29,33 @@ public static class AudioManagerFindOrLoadAudioClipExternalPatch
     }
 }
 
+/// <summary>
+/// AudioManager._Play (private; AudioManager.Play forwards to it): registers each scheduled sound effect (hit sounds, PlaySound
+/// events, hold sounds without an end time) as an effect voice of the offline mixer and maps the returned AudioSource to it.
+/// Active while capturing (RenderManager.IsCapturingActive) with RenderAudio on. The original always runs: it creates the
+/// AudioSource the game keeps using (its PlayScheduled call is blocked during rendering by another patch), and the game sets
+/// time/pitch/SetScheduledEndTime on it afterwards, which the <see cref="EffectSource"/> patches forward to the mapped state.
+/// The game volume is passed through; the start pitch is 1 because _Play sets pitch = 1 before PlayScheduled.
+/// </summary>
 [HarmonyPatch(typeof(AudioManager), "_Play")]
 public static class AudioManagerPlayPatch
 {
+    /// <summary>Opens the clip's source so its first chunk starts loading. Returns true (the original runs).</summary>
     [HarmonyPrefix]
     public static bool Prefix(string snd, double time, AudioMixerGroup group, float volume, int priority)
     {
         if (RenderManager.IsCapturingActive && RenderManager.Instance.Configuration.AudioConfig.RenderAudio)
         {
-            // Cache the clip on the main thread
+            // Cache the clip on the main Unity thread
             RenderManager.Instance.AudioMixer?.CacheClip(snd);
         }
         return true; // Let the original method execute to prevent NullReferenceException
     }
 
+    /// <summary>
+    /// Registers the sound at <paramref name="time"/> (absolute DSP time, converted to render time) as a non-looping effect voice,
+    /// maps <paramref name="__result"/> to it and queues the source's game object for deactivation at the end of the frame.
+    /// </summary>
     [HarmonyPostfix]
     // ReSharper disable once InconsistentNaming
     public static void Postfix(AudioSource __result, string snd, double time, AudioMixerGroup group, float volume, int priority)
@@ -63,6 +77,10 @@ public static class AudioManagerPlayPatch
 /// <summary>
 /// scrConductor.PlayWithEndTime: registers a looping effect voice until the end time. The AudioSource it creates with
 /// AudioManager.MakeSource is mapped to that voice (<see cref="AudioManagerMakeSourcePatch"/>).
+/// Active while capturing (RenderManager.IsCapturingActive) with RenderAudio on; the original always runs. The game calls it for
+/// hold sounds with an end time above 0 (scrConductor hold sound scheduling); it sets loop = true, pitch = 1, PlayScheduled(time) and
+/// SetScheduledEndTime(endTime) on the new source. pitch and SetScheduledEndTime reach the mapped state through the
+/// <see cref="EffectSource"/> patches; PlayScheduled is blocked during rendering by another patch.
 /// </summary>
 [HarmonyPatch(typeof(scrConductor), "PlayWithEndTime")]
 public static class PlayWithEndTimePatch
@@ -70,9 +88,14 @@ public static class PlayWithEndTimePatch
     /// <summary>State registered by the running PlayWithEndTime call, until its MakeSource returns. Main thread only.</summary>
     internal static SourceState? PendingState;
 
+    /// <summary>Clears <see cref="PendingState"/> when PlayWithEndTime returns or throws, so it cannot map a later MakeSource call.</summary>
     [HarmonyFinalizer]
     public static void Finalizer() => PendingState = null;
 
+    /// <summary>
+    /// Opens the clip's source and registers a looping voice from <paramref name="time"/> to <paramref name="endTime"/>
+    /// (absolute DSP times, converted to render time); the state waits in <see cref="PendingState"/>. Returns true (the original runs).
+    /// </summary>
     [HarmonyPrefix]
     public static bool Prefix(string snd, double time, double endTime, float volume, int priority)
     {
@@ -81,7 +104,7 @@ public static class PlayWithEndTimePatch
             var mixer = RenderManager.Instance.AudioMixer;
             if (mixer != null)
             {
-                // Cache the clip on the main thread
+                // Cache the clip on the main Unity thread
                 mixer.CacheClip(snd);
 
                 // Convert absolute DSP times to relative times in seconds from render start
@@ -96,10 +119,18 @@ public static class PlayWithEndTimePatch
     }
 }
 
-/// <summary>Maps the AudioSource created inside scrConductor.PlayWithEndTime to its state (<see cref="PlayWithEndTimePatch.PendingState"/>).</summary>
+/// <summary>
+/// Maps the AudioSource created inside scrConductor.PlayWithEndTime to its state (<see cref="PlayWithEndTimePatch.PendingState"/>).
+/// Active only while a PlayWithEndTime call registered a state (capturing with RenderAudio on); every other MakeSource call
+/// (including the one inside AudioManager._Play) is left unchanged.
+/// </summary>
 [HarmonyPatch(typeof(AudioManager), nameof(AudioManager.MakeSource))]
 public static class AudioManagerMakeSourcePatch
 {
+    /// <summary>
+    /// Takes the pending state, maps <paramref name="__result"/> to it and queues the source's game object for deactivation at
+    /// the end of the frame.
+    /// </summary>
     [HarmonyPostfix]
     // ReSharper disable once InconsistentNaming
     public static void Postfix(AudioSource __result)
@@ -173,6 +204,7 @@ internal static class EffectSource
 [HarmonyPatch(typeof(AudioSource), "isPlaying", MethodType.Getter)]
 public static class AudioSourceIsPlayingPatch
 {
+    /// <summary>When <see cref="EffectSource.TryGet"/> finds a mapped state, uses it and returns false (Unity is skipped); otherwise returns true.</summary>
     [HarmonyPrefix]
     // ReSharper disable once InconsistentNaming
     public static bool Prefix(AudioSource __instance, ref bool __result)
@@ -187,6 +219,7 @@ public static class AudioSourceIsPlayingPatch
 [HarmonyPatch(typeof(AudioSource), "time", MethodType.Getter)]
 public static class AudioSourceTimeGetterPatch
 {
+    /// <summary>When <see cref="EffectSource.TryGet"/> finds a mapped state, uses it and returns false (Unity is skipped); otherwise returns true.</summary>
     [HarmonyPrefix]
     // ReSharper disable once InconsistentNaming
     public static bool Prefix(AudioSource __instance, ref float __result)
@@ -204,6 +237,7 @@ public static class AudioSourceTimeGetterPatch
 [HarmonyPatch(typeof(AudioSource), "time", MethodType.Setter)]
 public static class AudioSourceTimePatch
 {
+    /// <summary>When <see cref="EffectSource.TryGet"/> finds a mapped state, uses it and returns false (Unity is skipped); otherwise returns true.</summary>
     [HarmonyPrefix]
     // ReSharper disable once InconsistentNaming
     public static bool Prefix(AudioSource __instance, float value)
@@ -214,10 +248,14 @@ public static class AudioSourceTimePatch
     }
 }
 
-/// <summary>AudioSource.timeSamples getter (<see cref="EffectSource"/>): clip position in samples of the clip.</summary>
+/// <summary>
+/// AudioSource.timeSamples getter (<see cref="EffectSource"/>): clip position in samples of the clip while playing; while not playing,
+/// the last value set through time or timeSamples (0 after Stop()).
+/// </summary>
 [HarmonyPatch(typeof(AudioSource), "timeSamples", MethodType.Getter)]
 public static class AudioSourceTimeSamplesGetterPatch
 {
+    /// <summary>When <see cref="EffectSource.TryGet"/> finds a mapped state, uses it and returns false (Unity is skipped); otherwise returns true.</summary>
     [HarmonyPrefix]
     // ReSharper disable once InconsistentNaming
     public static bool Prefix(AudioSource __instance, ref int __result)
@@ -232,6 +270,7 @@ public static class AudioSourceTimeSamplesGetterPatch
 [HarmonyPatch(typeof(AudioSource), "timeSamples", MethodType.Setter)]
 public static class AudioSourceTimeSamplesPatch
 {
+    /// <summary>When <see cref="EffectSource.TryGet"/> finds a mapped state, uses it and returns false (Unity is skipped); otherwise returns true.</summary>
     [HarmonyPrefix]
     // ReSharper disable once InconsistentNaming
     public static bool Prefix(AudioSource __instance, int value)
@@ -246,6 +285,7 @@ public static class AudioSourceTimeSamplesPatch
 [HarmonyPatch(typeof(AudioSource), "pitch", MethodType.Getter)]
 public static class AudioSourcePitchGetterPatch
 {
+    /// <summary>When <see cref="EffectSource.TryGet"/> finds a mapped state, uses it and returns false (Unity is skipped); otherwise returns true.</summary>
     [HarmonyPrefix]
     // ReSharper disable once InconsistentNaming
     public static bool Prefix(AudioSource __instance, ref float __result)
@@ -260,6 +300,7 @@ public static class AudioSourcePitchGetterPatch
 [HarmonyPatch(typeof(AudioSource), "pitch", MethodType.Setter)]
 public static class AudioSourcePitchPatch
 {
+    /// <summary>When <see cref="EffectSource.TryGet"/> finds a mapped state, uses it and returns false (Unity is skipped); otherwise returns true.</summary>
     [HarmonyPrefix]
     // ReSharper disable once InconsistentNaming
     public static bool Prefix(AudioSource __instance, float value)
@@ -274,6 +315,7 @@ public static class AudioSourcePitchPatch
 [HarmonyPatch(typeof(AudioSource), "SetScheduledEndTime", typeof(double))]
 public static class AudioSourceSetScheduledEndTimePatch
 {
+    /// <summary>When <see cref="EffectSource.TryGet"/> finds a mapped state, uses it and returns false (Unity is skipped); otherwise returns true.</summary>
     [HarmonyPrefix]
     // ReSharper disable once InconsistentNaming
     public static bool Prefix(AudioSource __instance, double time)
@@ -292,6 +334,7 @@ public static class AudioSourceSetScheduledEndTimePatch
 [HarmonyPatch(typeof(AudioSource), "Stop", new Type[0])]
 public static class AudioSourceStopPatch
 {
+    /// <summary>When <see cref="EffectSource.TryGet"/> finds a mapped state, uses it and returns false (Unity is skipped); otherwise returns true.</summary>
     [HarmonyPrefix]
     // ReSharper disable once InconsistentNaming
     public static bool Prefix(AudioSource __instance)
@@ -306,11 +349,13 @@ public static class AudioSourceStopPatch
 /// AudioManager.StopAllSounds destroys every source in liveSources (all AudioManager._Play and scrConductor.PlayWithEndTime sources),
 /// so every effect voice stops at the current render time, including ones scheduled to start later.
 /// Callers include scrConductor.PlayHitTimes (from its second call), ScrubMusicToTile/Time, KillAllSoundsCoroutine,
-/// scrController.FailAction and scnGame.Play.
+/// scrController.FailAction, scrController.DebugUpdate, scnGame.Play and PauseMenu.Choose.
+/// Active while capturing (RenderManager.IsCapturingActive) with RenderAudio on; the original always runs (it destroys the sources).
 /// </summary>
 [HarmonyPatch(typeof(AudioManager), nameof(AudioManager.StopAllSounds))]
 public static class AudioManagerStopAllSoundsPatch
 {
+    /// <summary>Stops every effect voice while capturing with RenderAudio on. The original always runs (no return value).</summary>
     [HarmonyPrefix]
     public static void Prefix()
     {

Patch/Engine/RenderEnvironmentPatches.cs

@@ -6,13 +6,40 @@ using UnityEngine;
 
 namespace ADOFAIRenderer.Patch.Engine;
 
+/// <summary>
+/// Unity engine patches that put the game on the offline render clock and the render resolution.
+/// <para>
+/// Render clock: while capturing (<see cref="RenderManager.IsCapturingActive"/>, stage &gt;= Render) and
+/// <c>RenderContext.TimePatch</c> is on (default on; a <c>RenderSession</c> can turn it off), the Unity time getters return
+/// the value captured at the capture start (<c>RenderManager.timeBase</c>, <c>unscaledTimeBase</c>, <c>dspTimeBase</c>,
+/// <c>frameCountBase</c>, read in <c>SetupPlay</c>) plus the render time <see cref="TimeSpent"/>. Each rendered frame then
+/// advances game time by exactly 1 / RenderFPS seconds, independent of how long the frame took to render and encode, and the
+/// clocks continue from their real values without a jump. The patches only affect managed callers of these getters
+/// (game and mod scripts).
+/// </para>
+/// <para>
+/// All prefixes run on the thread that calls the getter (normally the main Unity thread) and read <c>RenderManager</c> state
+/// without locks.
+/// </para>
+/// </summary>
 public static class RenderEnvironmentPatches
 {
+    /// <summary>
+    /// Render time of the current frame in seconds: <c>RenderManager.frameCount</c> / <c>RenderFPS</c>.
+    /// frameCount is reset to 0 when capture starts and incremented at the start of every frame (FirstUpdateHook).
+    /// </summary>
     private static double TimeSpent => RenderManager.Instance.frameCount / RenderManager.Instance.Configuration.RenderFPS;
         
+    /// <summary>
+    /// <c>Time.time</c> (scaled game time in seconds, float): returns timeBase + <see cref="TimeSpent"/> while capturing with
+    /// the time patch on. <c>Time.timeScale</c> is not applied to the render time.
+    /// </summary>
     [HarmonyPatch(typeof(Time), "time", MethodType.Getter)]
     public static class TimePatch
     {
+        /// <summary>Prefix of the <c>Time.time</c> getter.</summary>
+        /// <param name="__result">Replacement value in seconds.</param>
+        /// <returns>True to run the original getter; false when the render clock value is returned.</returns>
         [SuppressMessage("ReSharper", "InconsistentNaming")]
         public static bool Prefix(ref float __result)
         {
@@ -22,9 +49,13 @@ public static class RenderEnvironmentPatches
         }
     }
         
+    /// <summary><c>Time.timeAsDouble</c> (double precision of <c>Time.time</c>): timeBase + <see cref="TimeSpent"/>.</summary>
     [HarmonyPatch(typeof(Time), "timeAsDouble", MethodType.Getter)]
     public static class TimeAsDoublePatch
     {
+        /// <summary>Prefix of the getter; returns the render clock value while capturing with the time patch on.</summary>
+        /// <param name="__result">Replacement value in seconds.</param>
+        /// <returns>True to run the original getter; false when the render clock value is returned.</returns>
         [SuppressMessage("ReSharper", "InconsistentNaming")]
         public static bool Prefix(ref double __result)
         {
@@ -34,9 +65,18 @@ public static class RenderEnvironmentPatches
         }
     }
 
+    /// <summary>
+    /// <c>Time.unscaledTime</c> (time in seconds independent of <c>Time.timeScale</c>, float): unscaledTimeBase +
+    /// <see cref="TimeSpent"/>. Unscaled time is not advanced by <c>Time.captureDeltaTime</c> (it follows real time), so it is
+    /// replaced as well.
+    /// Reference: https://docs.unity3d.com/ScriptReference/Time-captureDeltaTime.html
+    /// </summary>
     [HarmonyPatch(typeof(Time), "unscaledTime", MethodType.Getter)]
     public static class UnscaledTimePatch
     {
+        /// <summary>Prefix of the getter; returns the render clock value while capturing with the time patch on.</summary>
+        /// <param name="__result">Replacement value in seconds.</param>
+        /// <returns>True to run the original getter; false when the render clock value is returned.</returns>
         [SuppressMessage("ReSharper", "InconsistentNaming")]
         public static bool Prefix(ref float __result)
         {
@@ -46,9 +86,15 @@ public static class RenderEnvironmentPatches
         }
     }
         
+    /// <summary>
+    /// <c>Time.unscaledTimeAsDouble</c> (double precision of <c>Time.unscaledTime</c>): unscaledTimeBase + <see cref="TimeSpent"/>.
+    /// </summary>
     [HarmonyPatch(typeof(Time), "unscaledTimeAsDouble", MethodType.Getter)]
     public static class UnscaledTimeAsDoublePatch
     {
+        /// <summary>Prefix of the getter; returns the render clock value while capturing with the time patch on.</summary>
+        /// <param name="__result">Replacement value in seconds.</param>
+        /// <returns>True to run the original getter; false when the render clock value is returned.</returns>
         [SuppressMessage("ReSharper", "InconsistentNaming")]
         public static bool Prefix(ref double __result)
         {
@@ -58,9 +104,17 @@ public static class RenderEnvironmentPatches
         }
     }
 
+    /// <summary>
+    /// <c>AudioSettings.dspTime</c> (audio system clock in seconds, double): dspTimeBase + <see cref="TimeSpent"/>.
+    /// The game schedules the song and computes the song position from this clock (<c>scrConductor</c>), so the level advances
+    /// by one render frame per frame. The offline audio mixer uses the same base (<c>RenderManager.dspTimeBase</c>).
+    /// </summary>
     [HarmonyPatch(typeof(AudioSettings), "dspTime", MethodType.Getter)]
     public static class DspTimePatch
     {
+        /// <summary>Prefix of the getter; returns the render clock value while capturing with the time patch on.</summary>
+        /// <param name="__result">Replacement value in seconds.</param>
+        /// <returns>True to run the original getter; false when the render clock value is returned.</returns>
         [SuppressMessage("ReSharper", "InconsistentNaming")]
         public static bool Prefix(ref double __result)
         {
@@ -70,9 +124,19 @@ public static class RenderEnvironmentPatches
         }
     }
         
+    /// <summary>
+    /// <c>AudioSource.PlayScheduled(double time)</c> (start playback at a dspTime): blocked for every AudioSource while
+    /// <see cref="RenderManager.IsActive"/> (stage &gt;= OnScene), so Unity plays no scheduled sound in real time. During
+    /// capture the song and the sound effects are produced offline by <c>OfflineAudioMixer</c>; sound effects reach it through
+    /// the <c>AudioManager._Play</c> and <c>scrConductor.PlayWithEndTime</c> patches (AudioPatches.cs).
+    /// </summary>
     [HarmonyPatch(typeof(AudioSource), "PlayScheduled")]
     public static class PlayScheduledPatch
     {
+        /// <summary>Prefix of <c>AudioSource.PlayScheduled</c>.</summary>
+        /// <param name="__instance">The AudioSource (unused).</param>
+        /// <param name="time">Scheduled start in dspTime seconds (unused).</param>
+        /// <returns>True to run the original method (not rendering); false to skip it (rendering).</returns>
         // ReSharper disable once InconsistentNaming
         public static bool Prefix(AudioSource __instance, double time)
         {
@@ -80,9 +144,16 @@ public static class RenderEnvironmentPatches
         }
     }
 
+    /// <summary>
+    /// <c>Time.frameCount</c> (frames since startup): frameCountBase + <c>RenderManager.frameCount</c> while capturing
+    /// (stage &gt;= Render) with <c>RenderContext.TimePatch</c> on.
+    /// </summary>
     [HarmonyPatch(typeof(Time), "frameCount", MethodType.Getter)]
     public static class FrameCountPatch
     {
+        /// <summary>Prefix of the getter; returns the replacement value under the conditions in the type summary.</summary>
+        /// <param name="__result">Replacement value.</param>
+        /// <returns>True to run the original getter; false when the replacement value is returned.</returns>
         [SuppressMessage("ReSharper", "InconsistentNaming")]
         public static bool Prefix(ref int __result)
         {
@@ -92,9 +163,13 @@ public static class RenderEnvironmentPatches
         }
     }
 
+    /// <summary><c>Time.deltaTime</c> (seconds since the previous frame, float): 1 / RenderFPS.</summary>
     [HarmonyPatch(typeof(Time), "deltaTime", MethodType.Getter)]
     public static class DeltaTimePatch
     {
+        /// <summary>Prefix of the getter; returns the render clock value while capturing with the time patch on.</summary>
+        /// <param name="__result">Replacement value in seconds.</param>
+        /// <returns>True to run the original getter; false when the render clock value is returned.</returns>
         [SuppressMessage("ReSharper", "InconsistentNaming")]
         public static bool Prefix(ref float __result)
         {
@@ -104,9 +179,13 @@ public static class RenderEnvironmentPatches
         }
     }
 
+    /// <summary><c>Time.unscaledDeltaTime</c> (timeScale-independent frame time in seconds, float): 1 / RenderFPS.</summary>
     [HarmonyPatch(typeof(Time), "unscaledDeltaTime", MethodType.Getter)]
     public static class UnscaledDeltaTimePatch
     {
+        /// <summary>Prefix of the getter; returns the render clock value while capturing with the time patch on.</summary>
+        /// <param name="__result">Replacement value in seconds.</param>
+        /// <returns>True to run the original getter; false when the render clock value is returned.</returns>
         [SuppressMessage("ReSharper", "InconsistentNaming")]
         public static bool Prefix(ref float __result)
         {
@@ -116,9 +195,18 @@ public static class RenderEnvironmentPatches
         }
     }
 
+    /// <summary>
+    /// <c>Screen.width</c> (window width in pixels): <c>RenderConfig.RenderWidth</c> while <see cref="RenderManager.IsActive"/>
+    /// (stage &gt;= OnScene) and <c>RenderContext.ScreenPatch</c> is on (default on). Game code that sizes render textures from
+    /// the screen size (for example <c>scrCamera</c> recreates <c>camRT</c> at Screen.width x Screen.height when the size
+    /// differs) then works at the output resolution independent of the window size.
+    /// </summary>
     [HarmonyPatch(typeof(Screen), "width", MethodType.Getter)]
     public static class ScreenWidthPatch
     {
+        /// <summary>Prefix of the getter; returns the replacement value under the conditions in the type summary.</summary>
+        /// <param name="__result">Replacement value.</param>
+        /// <returns>True to run the original getter; false when the replacement value is returned.</returns>
         [SuppressMessage("ReSharper", "InconsistentNaming")]
         public static bool Prefix(ref int __result)
         {
@@ -128,9 +216,15 @@ public static class RenderEnvironmentPatches
         }
     }
 
+    /// <summary>
+    /// <c>Screen.height</c> (window height in pixels): <c>RenderConfig.RenderHeight</c>; same conditions as <see cref="ScreenWidthPatch"/>.
+    /// </summary>
     [HarmonyPatch(typeof(Screen), "height", MethodType.Getter)]
     public static class ScreenHeightPatch
     {
+        /// <summary>Prefix of the getter; returns the replacement value under the conditions in the type summary.</summary>
+        /// <param name="__result">Replacement value.</param>
+        /// <returns>True to run the original getter; false when the replacement value is returned.</returns>
         [SuppressMessage("ReSharper", "InconsistentNaming")]
         public static bool Prefix(ref int __result)
         {
@@ -140,9 +234,22 @@ public static class RenderEnvironmentPatches
         }
     }
 
+    /// <summary>
+    /// <c>AudioSource.GetSpectrumData(float[] samples, int channel, FFTWindow window)</c> (FFT magnitudes of the source's current
+    /// output): while capturing (stage &gt;= Render) with <c>AdvancedConfig.ProcessAudio</c> on, fills <c>samples</c> with
+    /// <see cref="AudioSpectrumGenerator.GetSpectrumData"/> (spectrum of the song at the render time) for any AudioSource.
+    /// No AudioSource plays during capture, so the original would return silence. The game calls it from
+    /// <c>scrConductor</c>, <c>scrBarMaker</c> and the volume trackers for audio-reactive visuals.
+    /// </summary>
     [HarmonyPatch(typeof(AudioSource), "GetSpectrumData", typeof(float[]), typeof(int), typeof(FFTWindow))]
     public static class GetSpectrumDataPatch
     {
+        /// <summary>Prefix of <c>AudioSource.GetSpectrumData</c>.</summary>
+        /// <param name="__instance">The AudioSource queried (not used; the song spectrum is returned for every source).</param>
+        /// <param name="samples">Output array; its length is the number of spectrum bins.</param>
+        /// <param name="channel">Channel index requested by the caller.</param>
+        /// <param name="window">FFT window type requested by the caller.</param>
+        /// <returns>True to run the original method; false when the generated spectrum was written.</returns>
         [SuppressMessage("ReSharper", "InconsistentNaming")]
         public static bool Prefix(AudioSource __instance, float[] samples, int channel, FFTWindow window)
         {
@@ -152,9 +259,19 @@ public static class RenderEnvironmentPatches
         }
     }
 
+    /// <summary>
+    /// <c>AudioManager.FindOrLoadAudioClipExternal(string path, bool mp3Streaming, float length, bool stream)</c> (coroutine
+    /// that loads an external audio file of the level into <c>audioLib</c>): from stage Load with
+    /// <c>AdvancedConfig.ProcessAudio</c> on, forces <c>stream</c> to false. The game passes <c>stream</c> to
+    /// <c>DownloadHandlerAudioClip.streamAudio</c> for ogg/wav/aif/aiff files, so these clips are loaded as non-streaming
+    /// clips; the MP3 path uses <c>mp3Streaming</c> and ignores <c>stream</c>.
+    /// Reference: https://docs.unity3d.com/ScriptReference/Networking.DownloadHandlerAudioClip-streamAudio.html
+    /// </summary>
     [HarmonyPatch(typeof(AudioManager), "FindOrLoadAudioClipExternal", typeof(string), typeof(bool), typeof(float), typeof(bool))]
     public static class FindOrLoadAudioClipExternalPatch
     {
+        /// <summary>Prefix of <c>AudioManager.FindOrLoadAudioClipExternal</c>; the original always runs.</summary>
+        /// <param name="stream">Streaming flag of the load; set to false under the conditions above.</param>
         [SuppressMessage("ReSharper", "InconsistentNaming")]
         public static void Prefix(ref bool stream)
         {

Patch/Game/DetailedResultsPatch.cs

@@ -3,10 +3,27 @@ using HarmonyLib;
 
 namespace ADOFAIRenderer.Patch.Game;
 
+/// <summary>
+/// Hides the detailed results panel (per-judgement hit counts) that the game shows on the clear screen.
+/// <para>
+/// Patched member: <c>DetailedResults.Show()</c>. The game calls it from <c>scrController.OnLandOnPortal</c> when a level is won
+/// (and detailed results are enabled); it builds the result text per player, enables the component and activates
+/// <c>scrController.detailedResults</c>.
+/// </para>
+/// <para>
+/// Active while <see cref="RenderManager.IsActive"/> (stage &gt;= OnScene), so the panel does not appear in the rendered video
+/// during the delay after the level end.
+/// </para>
+/// </summary>
 [HarmonyPatch(typeof(DetailedResults))]
 // ReSharper disable once InconsistentNaming
 public static class DetailedResultsPatch
 {
+    /// <summary>
+    /// Prefix of <c>DetailedResults.Show</c>. While rendering, disables the component and deactivates its GameObject.
+    /// </summary>
+    /// <param name="__instance">The DetailedResults component being shown.</param>
+    /// <returns>True to run the original method (not rendering); false to skip it (rendering).</returns>
     [HarmonyPrefix]
     [HarmonyPatch("Show")]
     // ReSharper disable once InconsistentNaming

Patch/Game/EndscreenLanternsPatch.cs

@@ -4,10 +4,29 @@ using HarmonyLib;
 
 namespace ADOFAIRenderer.Patch.Game;
 
+/// <summary>
+/// Suppresses the end-screen lanterns (level complete / accuracy / speed trial lamps) shown after a clear.
+/// <para>
+/// Patched members: <c>EndscreenLanterns.Show(scrPlayer, float, int, bool)</c>, which activates the lantern set, sets the
+/// lantern texts and starts DOTween sequences (<c>chainSequence</c> for the chain drop, <c>lampSequences[3]</c> for the lamp
+/// effects), returning the number of lanterns shown; and <c>EndscreenLanterns.Hide()</c>, which deactivates the GameObject.
+/// </para>
+/// <para>
+/// Active while <see cref="RenderManager.IsActive"/> (stage &gt;= OnScene), so the lanterns and their tweens do not appear in
+/// the rendered video during the delay after the level end. See also <see cref="scrUIControllerPatch"/>.
+/// </para>
+/// </summary>
 [HarmonyPatch(typeof(EndscreenLanterns))]
 // ReSharper disable once InconsistentNaming
 public static class EndscreenLanternsPatch
 {
+    /// <summary>
+    /// Prefix of <c>EndscreenLanterns.Show</c>. While rendering, hides the lantern set (which also runs
+    /// <see cref="PrefixHide"/>) and reports zero lanterns shown.
+    /// </summary>
+    /// <param name="__instance">The lantern set being shown.</param>
+    /// <param name="__result">Return value of Show: number of lanterns shown; set to 0 when the original is skipped.</param>
+    /// <returns>True to run the original method (not rendering); false to skip it (rendering).</returns>
     [HarmonyPrefix]
     [HarmonyPatch("Show")]
     [SuppressMessage("ReSharper", "InconsistentNaming")]
@@ -22,6 +41,21 @@ public static class EndscreenLanternsPatch
         return false; // Skip original Show method
     }
 
+    /// <summary>
+    /// Prefix of <c>EndscreenLanterns.Hide</c>. While rendering, releases the lantern tweens started by an earlier Show
+    /// before the original deactivates the GameObject.
+    /// <para>
+    /// The private fields <c>lampSequences</c> (DOTween <c>Sequence[]</c>) and <c>chainSequence</c> (<c>Sequence</c>) are read
+    /// through Harmony <see cref="Traverse"/>. For each sequence, a public instance method <c>Kill(bool)</c> is looked up on the
+    /// object's runtime type by reflection and invoked with <c>false</c> when found; then the field slot is set to null.
+    /// In the game's DOTween.dll, <c>Kill(this Tween, bool complete = false)</c> is an extension method of
+    /// <c>DG.Tweening.TweenExtensions</c>, so the lookup on <c>Sequence</c> returns null and no Kill is invoked; the effect is
+    /// that the fields stop referencing the sequences, while the sequences themselves keep running in DOTween.
+    /// Reflection failures on a single sequence (including a null array element) are ignored. The original Hide always runs
+    /// afterwards.
+    /// </para>
+    /// </summary>
+    /// <param name="__instance">The lantern set being hidden.</param>
     [HarmonyPrefix]
     [HarmonyPatch("Hide")]
     [SuppressMessage("ReSharper", "InconsistentNaming")]

Patch/Game/LanguageSyncPatch.cs

@@ -5,11 +5,19 @@ using UnityEngine;
 namespace ADOFAIRenderer.Patch.Game;
 
 /// <summary>
-/// Synchronizes mod localization with ADOFAI's in-game language settings.
+/// Keeps the mod UI language (<see cref="LocalizationManager"/>) equal to the game language.
+/// <para>
+/// Patched members: <c>RDString.Setup()</c>, which initializes the game's string table and sets <c>RDString.language</c> from
+/// <c>Persistence.language</c> (it returns immediately when already initialized); and <c>RDString.ChangeLanguage(SystemLanguage)</c>,
+/// which stores the language in <c>Persistence.language</c>, clears the initialized flag and calls Setup again.
+/// </para>
+/// <para>Always active (independent of the render stage). Runs on the main Unity thread.</para>
 /// </summary>
 [HarmonyPatch(typeof(RDString))]
 internal static class LanguageSyncPatch
 {
+    /// <summary>Postfix of <c>RDString.ChangeLanguage</c>: applies the selected language to the mod UI.</summary>
+    /// <param name="language">Language passed to ChangeLanguage.</param>
     [HarmonyPatch(nameof(RDString.ChangeLanguage))]
     [HarmonyPostfix]
     public static void OnChangeLanguage(SystemLanguage language)
@@ -17,6 +25,10 @@ internal static class LanguageSyncPatch
         LocalizationManager.SetLanguage(language);
     }
 
+    /// <summary>
+    /// Postfix of <c>RDString.Setup</c>: applies <c>RDString.language</c> (the language resolved by the game) to the mod UI.
+    /// Runs on every Setup call, including the early-return calls made when the string table is already initialized.
+    /// </summary>
     [HarmonyPatch(nameof(RDString.Setup))]
     [HarmonyPostfix]
     public static void OnSetup()

Patch/Game/PersistencePatch.cs

@@ -3,9 +3,23 @@ using HarmonyLib;
 
 namespace ADOFAIRenderer.Patch.Game;
 
+/// <summary>
+/// Overrides two player settings read from <c>Persistence</c> during a render: the "skip intro" option and the planet colors.
+/// </summary>
 [HarmonyPatch(typeof(Persistence))]
 public static class PersistencePatch
 {
+    /// <summary>
+    /// Postfix of the <c>Persistence.skipIntroBehavior</c> getter (setting values Off / AfterFirstTry / Always).
+    /// <para>
+    /// <c>scrConductor.StartMusicCo</c> reads this setting when the song is scheduled and, for AfterFirstTry (after a death) or
+    /// Always (long intro, no checkpoint), sets <c>skipOffset</c>, which moves <c>dspTimeSong</c> back by the level offset and
+    /// starts the song part-way in. While <see cref="RenderManager.IsActive"/> (stage &gt;= OnScene) and the song has not
+    /// started yet (<c>scrConductor.hasSongStarted</c> false), the getter returns Off, so <c>skipOffset</c> stays false and the
+    /// song always plays from its start. The mod's offline BGM mixing, spectrum and video background timing assume this.
+    /// </para>
+    /// </summary>
+    /// <param name="__result">Value returned by the getter; replaced with <c>SkipIntroBehavior.Off</c> under the conditions above.</param>
     [HarmonyPostfix]
     [HarmonyPatch("skipIntroBehavior", MethodType.Getter)]
     // ReSharper disable once InconsistentNaming
@@ -19,6 +33,18 @@ public static class PersistencePatch
         }
     }
 
+    /// <summary>
+    /// Postfix of <c>Persistence.GetPlayerColor(bool red)</c>, which returns the player's saved planet color
+    /// (preset name or hex color from the general preferences; default red/blue otherwise). <c>PlanetRenderer</c> uses it to
+    /// color the fire (red) and ice (blue) planets.
+    /// <para>
+    /// Active from stage Load (render started, scene loading) until the stage returns to None. When the render configuration
+    /// sets <c>AdvancedConfig.firePlanetColor</c> (red) or <c>AdvancedConfig.icePlanetColor</c> (blue), that color replaces the
+    /// saved color; an unset (null) override keeps the game value. The saved preference itself is not changed.
+    /// </para>
+    /// </summary>
+    /// <param name="red">True for the fire (red) planet, false for the ice (blue) planet.</param>
+    /// <param name="__result">Color returned by the game; replaced by the configured override when set.</param>
     [HarmonyPostfix]
     [HarmonyPatch("GetPlayerColor")]
     // ReSharper disable once InconsistentNaming

Patch/Game/PlanetarySystemPatch.cs

@@ -3,9 +3,21 @@ using HarmonyLib;
 
 namespace ADOFAIRenderer.Patch.Game;
 
+/// <summary>
+/// Applies the configured color of the third (green, "wind") planet used by multi-planet levels.
+/// <para>
+/// Patched members: <c>PlanetarySystem.Init()</c>, which creates the planets including <c>planetGreen</c> (default color
+/// RGB 0.3, 0.7, 0.0); and <c>PlanetarySystem.ApplyMultiplanetColors()</c>, which recolors the extra planets
+/// (green, yellow, purple, ...) from the red/blue planet colors (skipped by the game when <c>GCS.staticPlanetColors</c> is set).
+/// Both postfixes reapply the override after the game has set its color.
+/// </para>
+/// <para>Active from stage Load until the stage returns to None. The fire/ice colors are handled by <see cref="PersistencePatch"/>.</para>
+/// </summary>
 [HarmonyPatch(typeof(PlanetarySystem))]
 public static class PlanetarySystemPatch
 {
+    /// <summary>Postfix of <c>PlanetarySystem.Init</c>: applies the wind planet color override to the new planets.</summary>
+    /// <param name="__instance">The planetary system that was initialized.</param>
     [HarmonyPostfix]
     [HarmonyPatch("Init")]
     // ReSharper disable once InconsistentNaming
@@ -14,6 +26,8 @@ public static class PlanetarySystemPatch
         ApplyWindPlanetColor(__instance);
     }
 
+    /// <summary>Postfix of <c>PlanetarySystem.ApplyMultiplanetColors</c>: reapplies the wind planet color override.</summary>
+    /// <param name="__instance">The planetary system whose extra planet colors were updated.</param>
     [HarmonyPostfix]
     [HarmonyPatch("ApplyMultiplanetColors")]
     // ReSharper disable once InconsistentNaming
@@ -22,6 +36,11 @@ public static class PlanetarySystemPatch
         ApplyWindPlanetColor(__instance);
     }
 
+    /// <summary>
+    /// Sets <c>planetGreen</c>'s renderer color to <c>AdvancedConfig.windPlanetColor</c> when a render is in progress
+    /// (stage != None) and the override is set. Does nothing when the override is null or the planet does not exist.
+    /// </summary>
+    /// <param name="planetarySystem">The planetary system to update.</param>
     private static void ApplyWindPlanetColor(PlanetarySystem planetarySystem)
     {
         if (RenderManager.Instance == null || RenderManager.Instance.stage == RenderStage.None) return;

Patch/Game/scnEditorPatch.cs

@@ -6,10 +6,28 @@ using UnityEngine.UI;
 
 namespace ADOFAIRenderer.Patch.Game;
 
+/// <summary>
+/// Adds the "Render" button to the level editor toolbar.
+/// <para>
+/// Patched member: <c>scnEditor.Start()</c>, the editor scene setup (it wires the toolbar buttons, including
+/// <c>buttonExit</c>). The postfix clones the exit button next to it and makes the clone start a render.
+/// </para>
+/// <para>
+/// Always active except when the mod features are disabled (<see cref="RenderMod.IsFeatureDisabled"/>, set from the
+/// driver warning dialog). Runs on the main Unity thread each time the editor scene starts.
+/// </para>
+/// </summary>
 [HarmonyPatch(typeof(scnEditor))]
 // ReSharper disable once InconsistentNaming
 public static class scnEditorPatch
 {
+    /// <summary>
+    /// Postfix of <c>scnEditor.Start</c>: instantiates a copy of <c>buttonExit</c> under the same parent, named
+    /// <c>buttonRender</c>, whose click handler is <see cref="RenderManager.StartRender"/>, and replaces its icon with the
+    /// editor's MoveCamera event sprite (24 x 24 units). Logs a message and adds nothing when the editor or exit button is missing.
+    /// When the icon child or the sprite is not found, the button keeps the exit icon.
+    /// </summary>
+    /// <param name="__instance">The editor scene component.</param>
     [HarmonyPostfix]
     [HarmonyPatch("Start")]
     // ReSharper disable once InconsistentNaming
@@ -38,8 +56,9 @@ public static class scnEditorPatch
         var images = buttonObj.GetComponentsInChildren<Image>();
         if (images.Length <= 1) return;
             
+        // images[0] is the background on the root, images[1] is the icon on the child.
+        // Sprite path: the icon of the editor's MoveCamera level event, loaded from the game's Resources.
         // ReSharper disable once Unity.UnknownResource
-        // images[0] is the background on the root, images[1] is the icon on the child
         var sprite = Resources.Load<Sprite>("LevelEditor/LevelEvents/MoveCamera");
         if (sprite == null) return;
             

Patch/Game/scnGamePatch.cs

@@ -6,10 +6,26 @@ using UnityEngine;
 
 namespace ADOFAIRenderer.Patch.Game;
 
+/// <summary>
+/// Patches of <c>scnGame</c> (custom level scene controller, also used by the editor's play mode): hides tiles and planets
+/// for the "non-tile" render option and replaces the background video player during a render.
+/// </summary>
 [HarmonyPatch(typeof(scnGame))]
 // ReSharper disable once InconsistentNaming
 public static class scnGamePatch
 {
+    /// <summary>
+    /// Postfix of <c>scnGame.Play(int seqID, bool remakeFloors)</c>, which starts (or restarts) play of the custom level:
+    /// it resets the conductor, camera and controller state for the given start tile.
+    /// <para>
+    /// Active from stage Load when <c>AdvancedConfig.NonTile</c> is enabled. Disables the renderers of every floor in
+    /// <c>scrLevelMaker.listFloors</c> (floor mesh, legacy sprite, icon, outline, top/bottom glow, multi-planet line,
+    /// hold mesh, dummy planets) and of every planet of every player (sprite mesh, core/tail/sparks particles, ring, glow,
+    /// face, samurai sprite), so only the background and decorations remain in the rendered video. The renderers are only
+    /// disabled; the objects keep running. Hold meshes re-enable themselves, so <c>RenderManager.OnLastUpdate</c> disables
+    /// them again every frame.
+    /// </para>
+    /// </summary>
     [HarmonyPostfix]
     [HarmonyPatch("Play")]
     public static void ProcessFloors()
@@ -47,6 +63,7 @@ public static class scnGamePatch
         }
         return;
 
+        // Disables every renderer that draws one planet (fire, ice, extra planets and floor dummy planets).
         void DisablePlanetRenderer(PlanetRenderer planet)
         {
             if (planet.sprite) DisableRenderer(planet.sprite.meshRenderer);
@@ -62,12 +79,29 @@ public static class scnGamePatch
             foreach (var renderer in renderers) DisableRenderer(renderer);
         }
 
+        // Sets Renderer.enabled = false; null or destroyed renderers are skipped (Unity null check).
         void DisableRenderer(Renderer? renderer)
         {
             if (renderer) renderer.enabled = false;
         }
     }
         
+    /// <summary>
+    /// Prefix of <c>scnGame.UpdateVideo()</c>, which sets up the level's background video on the native Unity
+    /// <c>VideoPlayer</c> (<c>scnGame.videoBG</c>): it reads <c>miscSettings.bgVideo</c>, loads a <c>VideoClip</c> for internal
+    /// (Resources / Addressables) and bundle levels or sets <c>videoBG.url</c> to the file next to the custom level, then calls
+    /// <c>Stop()</c>, <c>Prepare()</c> and sets <c>isLooping</c> from <c>loopVideo</c>. The game calls it from
+    /// <c>scnGame.FinishCustomLevelLoading</c> and from <c>scnGame.ReloadAssets</c> when <c>force</c> is true.
+    /// <para>
+    /// While <see cref="RenderManager.IsActive"/> (stage &gt;= OnScene), an external video file of a custom level is played by
+    /// <see cref="VideoBGPlayer"/> (FFmpeg decoder), which shows the frame for the render time of each frame. The native
+    /// <c>VideoPlayer</c> plays in real time and would drift from the offline render clock, so it is disabled for that case.
+    /// Internal and bundle levels (built-in <c>VideoClip</c> assets, not files) and a missing file use the original method.
+    /// </para>
+    /// <para>Outside a render, any <see cref="VideoBGPlayer"/> left on the video object is destroyed and the native player re-enabled.</para>
+    /// </summary>
+    /// <param name="__instance">The scene controller.</param>
+    /// <returns>True to run the original UpdateVideo; false when the mod handled the video (or there is none).</returns>
     [HarmonyPrefix]
     [HarmonyPatch("UpdateVideo")]
     // ReSharper disable once InconsistentNaming
@@ -109,7 +143,8 @@ public static class scnGamePatch
             return true; // Let the original print error
         }
 
-        // Disable native VideoPlayer component (to prevent it from attempting real-time playback and sync errors)
+        // Camera for the CameraFarPlane render mode: the VideoPlayer's target camera, or the "BGStaticCam" scene object
+        // when none is assigned.
         var targetCamera = __instance.videoBG.targetCamera;
         if (!targetCamera)
         {
@@ -120,6 +155,7 @@ public static class scnGamePatch
             }
         }
 
+        // Disable the native VideoPlayer so it does not play the video in real time alongside VideoBGPlayer.
         __instance.videoBG.enabled = false;
 
         // Add or retrieve our custom FFmpeg video background player

Patch/Game/scrCameraPatch.cs

@@ -3,16 +3,37 @@ using HarmonyLib;
 
 namespace ADOFAIRenderer.Patch.Game;
 
+/// <summary>
+/// Protects the camera render texture <c>scrCamera.camRT</c> when the custom frame rate effect is turned off while it is
+/// already off.
+/// <para>
+/// Patched member: <c>scrCamera.SetCustomFrameRate(bool enable, float frame)</c> (level effect that updates the screen at a
+/// lower frame rate). Enabling assigns a new RenderTexture to the camera quad material and refreshes it at <c>frame</c> FPS.
+/// Disabling calls <c>Release()</c> on the quad material's current <c>mainTexture</c> and assigns <c>camRT</c> back. When
+/// the effect was never enabled, <c>mainTexture</c> is <c>camRT</c> itself, so the original releases the live camera
+/// render texture.
+/// </para>
+/// <para>Always active (independent of the render stage).</para>
+/// </summary>
 [HarmonyPatch(typeof(scrCamera))]
 // ReSharper disable once InconsistentNaming
 public class scrCameraPatch
 {
+    /// <summary>
+    /// Prefix of <c>scrCamera.SetCustomFrameRate</c>. For a disable request while <c>enableCustomFPS</c> is already false,
+    /// stores the arguments in <c>enableCustomFPS</c> / <c>frameRate</c> and skips the original (no texture is released).
+    /// Enable requests and disable requests while the effect is on run the original.
+    /// </summary>
+    /// <param name="__instance">The camera.</param>
+    /// <param name="enable">True to turn the custom frame rate on, false to turn it off.</param>
+    /// <param name="frame">Custom frame rate in frames per second.</param>
+    /// <returns>True to run the original method; false to skip it.</returns>
     [HarmonyPrefix]
     [HarmonyPatch("SetCustomFrameRate")]
     [SuppressMessage("ReSharper", "InconsistentNaming")]
     private static bool FixCamRT(scrCamera __instance, bool enable, float frame)
     {
-        // There is an issue that `mainTexture.Release` triggers even if `mainTexture` is `camRT`, so mod tries to fix it
+        // Disable request while the effect is off: the quad material's mainTexture is camRT, which the original would Release().
         if (enable || __instance.enableCustomFPS != enable) return true;
             
         __instance.enableCustomFPS = enable;

Patch/Game/scrControllerPatch.cs

@@ -3,10 +3,25 @@ using HarmonyLib;
 
 namespace ADOFAIRenderer.Patch.Game;
 
+/// <summary>
+/// Keeps the game controller (<c>scrController</c>) in uninterrupted play during a render: no pause, no failure,
+/// no scene change after the clear, and no clear texts.
+/// <para>
+/// All patches are active while <see cref="RenderManager.IsActive"/> (stage &gt;= OnScene). RenderManager also sets
+/// <c>noFail</c>, <c>noFailInfiniteMargin</c> and <c>disableCongratsMessage</c> on the controller when the scene is ready.
+/// </para>
+/// </summary>
 [HarmonyPatch(typeof(scrController))]
 // ReSharper disable once InconsistentNaming
 public static class scrControllerPatch
 {
+    /// <summary>
+    /// Prefix of <c>scrController.TogglePauseGame()</c> (pause menu toggle; sets <c>Time.timeScale</c> to 0 or 1 and shows the
+    /// pause menu; also called from the pause button, the pause key and <c>OnApplicationPauseCallback</c>). Skipped while
+    /// rendering, so the level cannot be paused. The skipped call returns
+    /// false (Harmony default for the unset bool result).
+    /// </summary>
+    /// <returns>True to run the original method (not rendering); false to skip it (rendering).</returns>
     [HarmonyPrefix]
     [HarmonyPatch("TogglePauseGame")]
     public static bool PreventPause()
@@ -14,6 +29,12 @@ public static class scrControllerPatch
         return !RenderManager.IsActive;
     }
 
+    /// <summary>
+    /// Prefix of <c>scrController.PortalTravelAction(Portal)</c>, which leaves the level through a portal (next level,
+    /// level select, main menu, ...); the game calls it on entering the Won state for non-world levels and on input after a win.
+    /// Skipped while rendering, so the scene stays loaded for the delay after the level end.
+    /// </summary>
+    /// <returns>True to run the original method (not rendering); false to skip it (rendering).</returns>
     [HarmonyPrefix]
     [HarmonyPatch("PortalTravelAction")]
     public static bool PreventPortalTravel()
@@ -21,6 +42,11 @@ public static class scrControllerPatch
         return !RenderManager.IsActive;
     }
 
+    /// <summary>
+    /// Prefix of <c>scrController.FailAction(...)</c>, which enters the Fail state: stops the song and all sounds, pauses the
+    /// VFX video and shows the failure texts. Skipped while rendering.
+    /// </summary>
+    /// <returns>True to run the original method (not rendering); false to skip it (rendering).</returns>
     [HarmonyPrefix]
     [HarmonyPatch("FailAction")]
     public static bool PreventFailAction()
@@ -28,6 +54,11 @@ public static class scrControllerPatch
         return !RenderManager.IsActive;
     }
 
+    /// <summary>
+    /// Prefix of <c>scrController.Fail2Action()</c>, which moves from Fail to Fail2 (accuracy calculation, saving of the
+    /// best result for boss/custom boss levels, death counter). Skipped while rendering.
+    /// </summary>
+    /// <returns>True to run the original method (not rendering); false to skip it (rendering).</returns>
     [HarmonyPrefix]
     [HarmonyPatch("Fail2Action")]
     public static bool PreventFail2Action()
@@ -35,6 +66,11 @@ public static class scrControllerPatch
         return !RenderManager.IsActive;
     }
 
+    /// <summary>
+    /// Prefix of <c>scrController.OnPlayerDied(...)</c>, which kills the remaining players and calls FailAction when no other
+    /// player is alive. Skipped while rendering.
+    /// </summary>
+    /// <returns>True to run the original method (not rendering); false to skip it (rendering).</returns>
     [HarmonyPrefix]
     [HarmonyPatch("OnPlayerDied")]
     public static bool PreventPlayerDied()
@@ -42,6 +78,17 @@ public static class scrControllerPatch
         return !RenderManager.IsActive;
     }
 
+    /// <summary>
+    /// Postfix of <c>scrController.OnLandOnPortal(...)</c>, the win handler on the last tile: it sets and activates
+    /// <c>txtCongrats</c> / <c>txtAprilCongrats</c> / <c>txtAllStrictClear</c>, may show the detailed results and end-screen
+    /// lanterns, saves the result and changes the state to Won.
+    /// <para>
+    /// While rendering, clears and deactivates the three clear texts and disables the detailed results panel after the
+    /// original has run, so they do not appear in the rendered video. The Won state itself is kept: the default render end
+    /// condition (<c>RenderContext.EndCondition</c>) waits for it.
+    /// </para>
+    /// </summary>
+    /// <param name="__instance">The game controller.</param>
     [HarmonyPostfix]
     [HarmonyPatch("OnLandOnPortal")]
     public static void PreventWinTextsPostfix(scrController __instance)

Patch/Game/scrFloorPatch.cs

@@ -3,10 +3,25 @@ using HarmonyLib;
 
 namespace ADOFAIRenderer.Patch.Game;
 
+/// <summary>
+/// Prevents the end portal from being spawned on level tiles for the "non-tile" render option.
+/// <para>
+/// Patched member: <c>scrFloor.SpawnPortalParticles()</c>, which instantiates the animated portal prefab
+/// (<c>scrPortalParticles</c>: glow, particles, cap and icon) as a child of the floor. The game calls it from
+/// <c>scrLevelMaker</c>, <c>scrController</c> and <c>scrFloor</c> for the portal floor.
+/// </para>
+/// <para>
+/// Active from stage Load when <c>AdvancedConfig.NonTile</c> is enabled, and only for floors that belong to
+/// <c>scrLevelMaker.listFloors</c> (the level's tiles). See <see cref="scnGamePatch.ProcessFloors"/> for the other tile renderers.
+/// </para>
+/// </summary>
 [HarmonyPatch(typeof(scrFloor))]
 // ReSharper disable once InconsistentNaming
 public class scrFloorPatch
 {
+    /// <summary>Prefix of <c>scrFloor.SpawnPortalParticles</c>.</summary>
+    /// <param name="__instance">The floor that would receive the portal.</param>
+    /// <returns>True to run the original method (spawn the portal); false to skip it (non-tile render, level floor).</returns>
     [HarmonyPrefix]
     [HarmonyPatch("SpawnPortalParticles")]
     // ReSharper disable once InconsistentNaming

Patch/Game/scrHitTextManagerPatch.cs

@@ -3,10 +3,20 @@ using HarmonyLib;
 
 namespace ADOFAIRenderer.Patch.Game;
 
+/// <summary>
+/// Hides the judgement texts (e.g. Perfect, Early, Late) during a render unless the render configuration enables them.
+/// <para>
+/// Patched member: <c>scrHitTextManager.ShowHitText(HitMargin, scrPlanet, float, int?)</c>, which shows the hit margin
+/// text at the planet for each hit (the game itself skips it for no-HUD modes and hidden margins).
+/// </para>
+/// <para>Active while <see cref="RenderManager.IsActive"/> (stage &gt;= OnScene) and <c>RenderConfig.ShowJudgementText</c> is false.</para>
+/// </summary>
 [HarmonyPatch(typeof(scrHitTextManager), "ShowHitText")]
 // ReSharper disable once InconsistentNaming
 public class scrHitTextManagerPatch
 {
+    /// <summary>Prefix of <c>scrHitTextManager.ShowHitText</c>.</summary>
+    /// <returns>True to run the original method (not rendering, or judgement texts enabled); false to skip it.</returns>
     public static bool Prefix()
     {
         return !RenderManager.IsActive || RenderManager.Instance is { Configuration: { ShowJudgementText: true } };

Patch/Game/scrMistakesManagerPatch.cs

@@ -3,10 +3,25 @@ using HarmonyLib;
 
 namespace ADOFAIRenderer.Patch.Game;
 
+/// <summary>
+/// Keeps a render from writing custom level results to the player's save data.
+/// <para>
+/// Patched member: <c>scrMistakesManager.SaveCustom(string hash, bool wonLevel, float multiplier)</c>, which compares the
+/// run with the stored completion, accuracy, speed trial and death records of the custom level (keyed by the level hash),
+/// stores new bests through <c>Persistence</c> and returns an <c>EndLevelInfo</c>. The game calls it from
+/// <c>scrController.OnLandOnPortal</c> (custom level win) and <c>Fail2Action</c> (custom boss level failure).
+/// </para>
+/// <para>
+/// Active while <see cref="RenderManager.IsActive"/> (stage &gt;= OnScene); the run of a render is not stored as a player
+/// record. The skipped call returns a default <c>EndLevelInfo</c>.
+/// </para>
+/// </summary>
 [HarmonyPatch(typeof(scrMistakesManager))]
 // ReSharper disable once InconsistentNaming
 public static class scrMistakesManagerPatch
 {
+    /// <summary>Prefix of <c>scrMistakesManager.SaveCustom</c>.</summary>
+    /// <returns>True to run the original method (not rendering); false to skip it (rendering).</returns>
     [HarmonyPrefix]
     [HarmonyPatch("SaveCustom")]
     public static bool PreventSaveCustom()

Patch/Game/scrPlayerManagerPatch.cs

@@ -3,10 +3,27 @@ using HarmonyLib;
 
 namespace ADOFAIRenderer.Patch.Game;
 
+/// <summary>
+/// Replaces the "any valid input" check with a render-controlled value, so player input cannot affect the level during a render.
+/// <para>
+/// Patched member: <c>scrPlayerManager.AnyValidInputWasTriggered()</c>, true when any player pressed a valid key this frame.
+/// <c>scrController</c> uses it to leave the press-to-start wait, to restart after a failure (<c>Fail2_Update</c>) and to
+/// leave the level after a win (<c>Won_Update</c>).
+/// </para>
+/// <para>
+/// Active while <see cref="RenderManager.IsActive"/> (stage &gt;= OnScene). The result is true only while
+/// <c>RenderManager.countdown</c> is 0 and <c>RenderManager.frameCount</c> is 0, that is, after the 3 second countdown in
+/// <c>SetupPlay</c> has ended and reset the frame counter and before the next frame increments it; it is false otherwise.
+/// <c>SetupPlay</c> also sets <c>scrController.levelWasSkipped</c>, which ends the press-to-start wait independently of input.
+/// </para>
+/// </summary>
 [HarmonyPatch(typeof(scrPlayerManager))]
 // ReSharper disable once InconsistentNaming
 public static class scrPlayerManagerPatch
 {
+    /// <summary>Prefix of <c>scrPlayerManager.AnyValidInputWasTriggered</c>.</summary>
+    /// <param name="__result">Return value used when the original is skipped (see class summary).</param>
+    /// <returns>True to run the original method (not rendering); false to skip it (rendering).</returns>
     [HarmonyPrefix]
     [HarmonyPatch("AnyValidInputWasTriggered")]
     // ReSharper disable once InconsistentNaming

Patch/Game/scrPortalParticlesPatch.cs

@@ -4,10 +4,26 @@ using UnityEngine;
 
 namespace ADOFAIRenderer.Patch.Game;
 
+/// <summary>
+/// Makes the end portal particle systems run on scaled game time during a render.
+/// <para>
+/// Patched member: <c>scrPortalParticles.Start()</c> (the animated portal spawned by <c>scrFloor.SpawnPortalParticles</c>;
+/// Start pre-simulates its particle system for 1 second and plays it).
+/// </para>
+/// <para>
+/// Active from stage Load. RenderManager sets <c>Time.captureDeltaTime</c> to 1 / RenderFPS, which advances scaled time by a
+/// fixed step per frame; unscaled time is not affected by captureDeltaTime and follows real time. A particle system with
+/// <c>main.useUnscaledTime</c> would therefore play at the real (slower or faster) frame rate of the offline render, so the
+/// postfix sets it to false on every particle system under the portal (including inactive children).
+/// Reference: https://docs.unity3d.com/ScriptReference/Time-captureDeltaTime.html
+/// </para>
+/// </summary>
 [HarmonyPatch(typeof(scrPortalParticles))]
 // ReSharper disable once InconsistentNaming
 public static class scrPortalParticlesPatch
 {
+    /// <summary>Postfix of <c>scrPortalParticles.Start</c>: sets <c>useUnscaledTime = false</c> on all child particle systems.</summary>
+    /// <param name="__instance">The portal that started.</param>
     [HarmonyPostfix]
     [HarmonyPatch("Start")]
     // ReSharper disable once InconsistentNaming

Patch/Game/scrPressToStartPatch.cs

@@ -3,10 +3,26 @@ using HarmonyLib;
 
 namespace ADOFAIRenderer.Patch.Game;
 
+/// <summary>
+/// Hides the "press any key to begin" text of the first level start of a render.
+/// <para>
+/// Patched member: <c>scrPressToStart.ShowText()</c>, which sets the press/tap-to-begin text and shows the difficulty
+/// selector (<c>scrUIController.ShowDifficultyContainer</c>). <c>scrController</c> calls it before waiting for the start input.
+/// </para>
+/// <para>
+/// Active once per render: <c>RenderManager.skipPressToStart</c> is set when the render loads <c>scnGame</c> and cleared by
+/// the first ShowText call (or when the render stops). Later ShowText calls run the original.
+/// </para>
+/// </summary>
 [HarmonyPatch(typeof(scrPressToStart))]
 // ReSharper disable once InconsistentNaming
 public class scrPressToStartPatch
 {
+    /// <summary>
+    /// Prefix of <c>scrPressToStart.ShowText</c>. When <c>skipPressToStart</c> is set, clears it, hides the difficulty
+    /// selector and skips the original.
+    /// </summary>
+    /// <returns>True to run the original method; false to skip it (first ShowText of a render).</returns>
     [HarmonyPrefix]
     [HarmonyPatch("ShowText")]
     private static bool PreventShowText()

Patch/Game/scrShowIfDebugPatch.cs

@@ -6,10 +6,31 @@ using UnityEngine.UI;
 
 namespace ADOFAIRenderer.Patch.Game;
 
+/// <summary>
+/// Replaces the game's status text (normally "Autoplay", "Auto tile" or "Debug Mode") with the render status.
+/// <para>
+/// Patched member: <c>scrShowIfDebug.Update()</c>, which each frame sets its UI <c>Text</c> (<c>txt</c>) to the autoplay /
+/// auto-tile / debug label or hides it (no-HUD modes, recording mode), in <c>defaultColor</c> (green) or orange for auto tiles.
+/// </para>
+/// <para>
+/// Active while <see cref="RenderManager.IsActive"/> (stage &gt;= OnScene). The postfix overwrites whatever the original set,
+/// every frame, so the text is shown even in the game's no-HUD modes.
+/// </para>
+/// </summary>
 [HarmonyPatch(typeof(scrShowIfDebug))]
 // ReSharper disable once InconsistentNaming
 public static class scrShowIfDebugPatch
 {
+    /// <summary>
+    /// Postfix of <c>scrShowIfDebug.Update</c>. Shows, in the default (green) color:
+    /// <list type="bullet">
+    /// <item>"Render in Ns.." during the countdown (N = <c>RenderManager.countdown</c>, seconds), otherwise "Render";</item>
+    /// <item>after the end condition is met (<c>endFrame</c> != -1), a second line "Waiting for X.Xs.." with the remaining
+    /// part of <c>DelayAfterEnd</c> in render seconds ((frameCount - endFrame) / RenderFPS elapsed), clamped at 0.</item>
+    /// </list>
+    /// </summary>
+    /// <param name="___txt">Private field <c>txt</c>: the status Text component.</param>
+    /// <param name="___defaultColor">Private field <c>defaultColor</c>: the game's status text color.</param>
     [HarmonyPostfix]
     [HarmonyPatch("Update")]
     [SuppressMessage("ReSharper", "InconsistentNaming")]

Patch/Game/scrUIControllerPatch.cs

@@ -3,10 +3,26 @@ using HarmonyLib;
 
 namespace ADOFAIRenderer.Patch.Game;
 
+/// <summary>
+/// Hides the end-screen lanterns again right after the game shows them.
+/// <para>
+/// Patched member: <c>scrUIController.ShowEndscreenLanterns()</c>, which calls <c>EndscreenLanterns.Show</c> for each player's
+/// lantern set (and fades the end-screen flash in co-op). <c>scrController.OnLandOnPortal</c> calls it on a win.
+/// </para>
+/// <para>
+/// Active while <see cref="RenderManager.IsActive"/> (stage &gt;= OnScene). Works together with <see cref="EndscreenLanternsPatch"/>,
+/// which already skips <c>EndscreenLanterns.Show</c> during a render.
+/// </para>
+/// </summary>
 [HarmonyPatch(typeof(scrUIController))]
 // ReSharper disable once InconsistentNaming
 public class scrUIControllerPatch
 {
+    /// <summary>
+    /// Postfix of <c>scrUIController.ShowEndscreenLanterns</c>: calls <c>HideEndscreenLanterns()</c>, which runs
+    /// <c>EndscreenLanterns.Hide</c> on every lantern set.
+    /// </summary>
+    /// <param name="__instance">The UI controller.</param>
     [HarmonyPostfix]
     [HarmonyPatch("ShowEndscreenLanterns")]
     // ReSharper disable once InconsistentNaming

RenderMod.cs

@@ -14,12 +14,30 @@ using Object = UnityEngine.Object;
 
 namespace ADOFAIRenderer;
 
+/// <summary>
+/// MelonLoader entry point of the mod. Loads the settings and localization, points FFmpeg.AutoGen at the native
+/// FFmpeg libraries, and creates the persistent manager objects (RenderManager, FirstUpdateHook, RendererUIManager).
+/// </summary>
 internal class RenderMod : MelonMod
 {
+    /// <summary>
+    /// When true, the render button is not added to the level editor (scnEditorPatch checks it in scnEditor.Start).
+    /// Set by the user from the NVIDIA driver warning dialog (FirstUpdateHook). Main thread only.
+    /// </summary>
     // ReSharper disable once MemberCanBePrivate.Global
     public static bool IsFeatureDisabled = false;
+
+    /// <summary>
+    /// Expiration time of this build (UTC). After it, the render configuration window shows an "expired" note next to
+    /// the version text. It does not block rendering.
+    /// </summary>
     public static DateTime ExpirationTime = new(2026, 11, 21, 0, 0, 0, DateTimeKind.Utc);
 
+    /// <summary>
+    /// Called once by MelonLoader after the mod assembly is loaded.
+    /// The native FFmpeg libraries are loaded from MelonLoader's UserLibs directory.
+    /// The three manager GameObjects are marked DontDestroyOnLoad so they survive scene changes.
+    /// </summary>
     public override void OnInitializeMelon()
     {
         GlobalSettings.Load();
@@ -39,6 +57,10 @@ internal class RenderMod : MelonMod
         ModAssets.Load();
     }
 
+    /// <summary>
+    /// Called by MelonLoader when the game quits. Aborts an active render (encoders disposed, render thread joined,
+    /// unfinished output file deleted) through RenderManager.CleanUpActiveRender.
+    /// </summary>
     public override void OnApplicationQuit()
     {
         if (RenderManager.Instance == null) return;

UI/CommonWarningDialogUI.cs

@@ -11,14 +11,29 @@ using Image = UnityEngine.UI.Image;
 
 namespace ADOFAIRenderer.UI;
 
+/// <summary>
+/// Description of one button of a <see cref="CommonWarningDialogUI"/> dialog: label, click action and optional color.
+/// </summary>
 internal class DialogButton
 {
     // ReSharper disable FieldCanBeMadeReadOnly.Global
+    /// <summary>Button label, shown as given (callers pass already localized text).</summary>
     public string Text;
+
+    /// <summary>
+    /// Action run on the main Unity thread when the button is clicked. The dialog is destroyed after the action
+    /// returns, also when the action throws (the exception is logged).
+    /// </summary>
     public Action OnClick;
+
+    /// <summary>Normal (idle) background color of the button; <c>null</c> keeps the O5Kit theme button color.</summary>
     public Color? BackgroundColor;
     // ReSharper restore FieldCanBeMadeReadOnly.Global
 
+    /// <summary>Creates a button description.</summary>
+    /// <param name="text">Button label.</param>
+    /// <param name="onClick">Action run on click, before the dialog closes.</param>
+    /// <param name="backgroundColor">Optional normal background color; <c>null</c> uses the theme color.</param>
     public DialogButton(string text, Action onClick, Color? backgroundColor = null)
     {
         Text = text;
@@ -27,10 +42,29 @@ internal class DialogButton
     }
 }
 
+/// <summary>
+/// Modal message dialog with a title, a description and one or more buttons.
+/// <para>
+/// Each <see cref="ShowDialog"/> call creates its own GameObject (kept across scene loads) with a screen-space overlay
+/// canvas: a translucent full-screen backdrop that blocks input to everything below, and an O5Kit window on top of it.
+/// While the dialog exists, every enabled UI Toolkit root (<see cref="UIDocument"/>) is disabled so that it cannot
+/// receive input; the roots are enabled again in <see cref="OnDestroy"/>. Clicking any button runs its action and then
+/// destroys the dialog. All members run on the main Unity thread.
+/// </para>
+/// </summary>
 internal class CommonWarningDialogUI : MonoBehaviour
 {
+    /// <summary>
+    /// The most recently created dialog, or <c>null</c> when that dialog has been destroyed.
+    /// <c>FirstUpdateHook</c> checks it to wait until a startup dialog is closed.
+    /// If several dialogs are open at once, this refers to the newest one only.
+    /// </summary>
     public static CommonWarningDialogUI? Instance { get; private set; }
+
+    /// <summary>UI Toolkit root elements disabled by this dialog, enabled again when the dialog is destroyed.</summary>
     private readonly List<VisualElement> _disabledElements = new();
+
+    /// <summary>O5Kit window holding the title, description and buttons; disposed in <see cref="OnDestroy"/>.</summary>
     private O5Window? _window;
 
     private void Awake()
@@ -38,6 +72,10 @@ internal class CommonWarningDialogUI : MonoBehaviour
         Instance = this;
     }
 
+    /// <summary>
+    /// Disposes the window, enables the UI Toolkit roots disabled in <see cref="Initialize"/> and clears
+    /// <see cref="Instance"/> if it still refers to this dialog.
+    /// </summary>
     private void OnDestroy()
     {
         _window?.Dispose();
@@ -58,6 +96,15 @@ internal class CommonWarningDialogUI : MonoBehaviour
         }
     }
 
+    /// <summary>
+    /// Creates and shows a new dialog. Must be called on the main Unity thread.
+    /// </summary>
+    /// <param name="title">Window title text.</param>
+    /// <param name="description">Body text, centered and word-wrapped; TextMeshPro rich text tags are allowed.</param>
+    /// <param name="buttons">
+    /// Buttons laid out left to right with equal widths. With no buttons nothing is shown, because the dialog
+    /// has no close button and could not be dismissed.
+    /// </param>
     public static void ShowDialog(string title, string description, params DialogButton[] buttons)
     {
         if (buttons.Length == 0) return;
@@ -68,8 +115,14 @@ internal class CommonWarningDialogUI : MonoBehaviour
         dialog.Initialize(title, description, buttons);
     }
 
+    /// <summary>
+    /// Builds the canvas, backdrop, window and contents. Layout sizes are in canvas units at the 1920x1080 reference
+    /// resolution of the <see cref="CanvasScaler"/>.
+    /// </summary>
     private void Initialize(string title, string description, DialogButton[] buttons)
     {
+        // uGUI buttons need an EventSystem to receive clicks. When the current scene has none, a child EventSystem
+        // is created; it is destroyed together with the dialog.
         if (!UnityEngine.EventSystems.EventSystem.current)
         {
             var eventSystemObj = new GameObject("EventSystem");
@@ -78,6 +131,8 @@ internal class CommonWarningDialogUI : MonoBehaviour
             eventSystemObj.AddComponent<UnityEngine.EventSystems.StandaloneInputModule>();
         }
 
+        // Disable every enabled UI Toolkit root so that it ignores input while the dialog is open.
+        // Roots that are already disabled are left alone and are not re-enabled in OnDestroy.
         foreach (var doc in FindObjectsByType<UIDocument>(FindObjectsSortMode.None))
         {
             if (doc && doc.rootVisualElement is { enabledSelf: true })
@@ -87,14 +142,17 @@ internal class CommonWarningDialogUI : MonoBehaviour
             }
         }
 
-        // Set UI layer (5)
+        // Set UI layer (5, Unity's built-in "UI" layer)
         gameObject.layer = 5;
 
-        // Canvas setup
+        // Canvas setup.
+        // Sorting order 32766 draws the dialog above the RendererUIManager window canvas (32000), the render overlays
+        // (DebugMonitorUI 9999, EscapeHandlerUI 10000) and below FFmpegDownloadUI (32767, the largest sorting order).
         var canvas = gameObject.AddComponent<Canvas>();
         canvas.renderMode = RenderMode.ScreenSpaceOverlay;
         canvas.sortingOrder = 32766;
 
+        // Scale with screen size against a 1920x1080 reference; match 0.5 blends width and height scaling equally.
         var scaler = gameObject.AddComponent<CanvasScaler>();
         scaler.uiScaleMode = CanvasScaler.ScaleMode.ScaleWithScreenSize;
         scaler.referenceResolution = new Vector2(1920, 1080);
@@ -105,7 +163,8 @@ internal class CommonWarningDialogUI : MonoBehaviour
 
         var ctx = RendererUIManager.Context;
 
-        // 1. Create full screen backdrop (scrim) to block background input
+        // 1. Create full screen backdrop (scrim) to block background input.
+        //    Black at 65% opacity, stretched over the whole canvas; raycastTarget makes it swallow clicks.
         var bgPanelObj = new GameObject("Backdrop");
         bgPanelObj.transform.SetParent(transform, false);
         bgPanelObj.layer = 5;
@@ -120,7 +179,8 @@ internal class CommonWarningDialogUI : MonoBehaviour
         bgRect.offsetMin = Vector2.zero;
         bgRect.offsetMax = Vector2.zero;
 
-        // 2. Create actual native O5Window
+        // 2. Create the O5Kit window as a child of the backdrop: 540x240 units, draggable, fixed size,
+        //    no close button (the dialog closes only through its buttons), 16-unit inner padding.
         _window = O5Window.Create(ctx, bgPanelObj.transform, new O5WindowOptions
         {
             Id = "RendererMod_WarningDialog",
@@ -133,7 +193,8 @@ internal class CommonWarningDialogUI : MonoBehaviour
             Padding = new RectOffset(16, 16, 16, 16)
         });
 
-        // 3. Build content inside window.Content
+        // 3. Build content inside window.Content: a vertical stack of the description (takes the remaining height)
+        //    and the button row (40 units high), 16 units apart.
         var content = _window.Content;
 
         var vLayout = content.gameObject.AddComponent<VerticalLayoutGroup>();
@@ -144,7 +205,7 @@ internal class CommonWarningDialogUI : MonoBehaviour
         vLayout.childForceExpandWidth = true;
         vLayout.childForceExpandHeight = false;
 
-        // Description text
+        // Description text: 18 pt, centered, word-wrapped, light gray (88% white)
         var descText = O5Factory.ControlText(ctx, content, 18f, noPad: true);
         descText.text = description;
         descText.alignment = TextAlignmentOptions.Center;
@@ -157,7 +218,7 @@ internal class CommonWarningDialogUI : MonoBehaviour
         descLE.flexibleWidth = 1f;
         descLE.flexibleHeight = 1f;
 
-        // Button action row
+        // Button action row: buttons share the row width equally, 10 units apart
         var btnRowObj = new GameObject("ButtonRow");
         btnRowObj.transform.SetParent(content, false);
         var btnRowRect = btnRowObj.AddComponent<RectTransform>();
@@ -176,6 +237,7 @@ internal class CommonWarningDialogUI : MonoBehaviour
         for (var i = 0; i < buttons.Length; i++)
         {
             var btnData = buttons[i];
+            // The click handler runs the caller's action, logs any exception from it, and always destroys the dialog.
             var btn = O5Factory.Button(
                 ctx: ctx,
                 parent: btnRowRect,

UI/DebugMonitorUI.cs

@@ -8,39 +8,73 @@ using UnityEngine.UI;
 
 namespace ADOFAIRenderer.UI;
 
+/// <summary>
+/// On-screen overlay shown while a render is running: a statistics panel in the top-right corner and a level progress
+/// bar near the bottom of the screen.
+/// <para>
+/// Created by <c>RenderManager.StartFFmpegThread</c> on a GameObject kept across scene loads, and reused for later
+/// renders. The overlay is drawn on the game screen only; it is not part of the encoded video frames.
+/// <see cref="Update"/> rebuilds the text every frame on the main Unity thread.
+/// </para>
+/// </summary>
 internal class DebugMonitorUI : MonoBehaviour
 {
     // --- Progress Bar UI Configuration Constants ---
+    // Sizes and positions are canvas units at the 1920x1080 reference resolution of the CanvasScaler.
+
+    /// <summary>Width of the progress bar; the fill width is <c>BarWidth * progress</c>.</summary>
     private const float BarWidth = 800f;
+    /// <summary>Height of the progress bar.</summary>
     private const float BarHeight = 28f;
+    /// <summary>Horizontal offset of the bar center from the screen center (0 = centered).</summary>
     private const float BarPosX = 0f;
+    /// <summary>Vertical offset of the bar center from the screen center; -420 is 120 units above the bottom edge (540 - 420).</summary>
     private const float BarPosY = -420f; // Y position relative to screen center (Reference: 1920x1080)
+    /// <summary>Font size of the percentage text drawn on the bar.</summary>
     private const int BarTextFontSize = 16; // Increased font size for visibility
+    /// <summary>Unfilled bar color: opaque near-black with a slight blue tint.</summary>
     private static readonly Color BarBackgroundColor = new(0.08f, 0.08f, 0.1f, 1.0f);
+    /// <summary>Filled part color: opaque cyan (#00CCFF).</summary>
     private static readonly Color BarFillColor = new(0.0f, 0.8f, 1.0f, 1.0f); // Sleek cyan/blue
+    /// <summary>Percentage text color: opaque white.</summary>
     private static readonly Color BarTextColor = new(1.0f, 1.0f, 1.0f, 1.0f);
 
     // --- Progress Bar Outline Configuration Constants ---
+
+    /// <summary>Color of the uGUI <see cref="Outline"/> drawn around the bar background.</summary>
     private static readonly Color BarOutlineColor = Color.white; // Contrasting white outline
+    /// <summary>
+    /// <c>Outline.effectDistance</c> of the bar outline: the background is redrawn shifted by +-3 units on both axes,
+    /// which shows as a border about 3 units wide.
+    /// </summary>
     private static readonly Vector2 BarOutlineDistance = new(3.0f, -3.0f); // Outline thickness
 
+    /// <summary>Statistics text inside the top-right panel.</summary>
     private TextMeshProUGUI _text = null!;
+    /// <summary>Progress bar background object (parent of the fill and the percentage text).</summary>
     private GameObject _progressBarObj = null!;
+    /// <summary>Progress bar fill object.</summary>
     private GameObject _progressBarFillObj = null!;
+    /// <summary>Fill rect, anchored to the left edge of the bar; its width is set every frame.</summary>
     private RectTransform _fillRect = null!;
+    /// <summary>Text on the bar: percentage and "current floor / last floor index".</summary>
     private TextMeshProUGUI _progressText = null!;
 
+    /// <summary>
+    /// Builds the overlay canvas, the statistics panel and the progress bar. Layout values are canvas units at the
+    /// 1920x1080 reference resolution.
+    /// </summary>
     private void Start()
     {
-        // Set UI layer (5)
+        // Set UI layer (5, Unity's built-in "UI" layer)
         gameObject.layer = 5;
 
-        // Canvas setup
+        // Canvas setup. Sorting order 9999 is below EscapeHandlerUI (10000) and the dialogs/windows of the mod.
         var canvas = gameObject.AddComponent<Canvas>();
         canvas.renderMode = RenderMode.ScreenSpaceOverlay;
         canvas.sortingOrder = 9999;
 
-        // Dynamic resolution scaling setup (Reference: 1920x1080)
+        // Dynamic resolution scaling against a 1920x1080 reference resolution; match 0.5 blends width and height
         var scaler = gameObject.AddComponent<CanvasScaler>();
         scaler.uiScaleMode = CanvasScaler.ScaleMode.ScaleWithScreenSize;
         scaler.referenceResolution = new Vector2(1920, 1080);
@@ -49,7 +83,7 @@ internal class DebugMonitorUI : MonoBehaviour
 
         gameObject.AddComponent<GraphicRaycaster>();
 
-        // Create background panel
+        // Create background panel: 360x220 units, pivot and anchor at the top-right corner, inset 30 units from both edges
         var panelObj = new GameObject("BackgroundPanel");
         panelObj.transform.SetParent(transform, false);
         panelObj.layer = 5;
@@ -64,7 +98,7 @@ internal class DebugMonitorUI : MonoBehaviour
         panelRect.anchoredPosition = new Vector2(-30, -30);
         panelRect.sizeDelta = new Vector2(360, 220);
 
-        // Create text
+        // Create text: 16 pt rich text, top-left aligned, filling the panel minus a 20-unit margin
         var textObj = new GameObject("MonitorText");
         textObj.transform.SetParent(panelObj.transform, false);
         textObj.layer = 5;
@@ -74,11 +108,11 @@ internal class DebugMonitorUI : MonoBehaviour
         _text.fontSize = 16;
         _text.alignment = TextAlignmentOptions.TopLeft;
 
-        // Prevent TMPro text clipping
+        // Wrap long lines and let text that exceeds the panel height overflow instead of being truncated
         _text.textWrappingMode = TextWrappingModes.Normal;
         _text.overflowMode = TextOverflowModes.Overflow;
 
-        // Load and apply font
+        // Apply the mod's bundled font (loaded by ModAssets.Load at mod initialization)
         _text.font = ModAssets.NanumSquareNeoNormal;
 
         var textRect = textObj.GetComponent<RectTransform>();
@@ -88,7 +122,7 @@ internal class DebugMonitorUI : MonoBehaviour
         textRect.offsetMax = new Vector2(-20, -20);
 
         // --- Progress Bar UI Setup ---
-        // 1. Progress Bar Container
+        // 1. Progress Bar Container: centered anchor/pivot, placed at (BarPosX, BarPosY) from the screen center
         _progressBarObj = new GameObject("ProgressBar");
         _progressBarObj.transform.SetParent(transform, false);
         _progressBarObj.layer = 5;
@@ -108,7 +142,8 @@ internal class DebugMonitorUI : MonoBehaviour
         barRect.anchoredPosition = new Vector2(BarPosX, BarPosY);
         barRect.sizeDelta = new Vector2(BarWidth, BarHeight);
 
-        // 2. Progress Bar Fill
+        // 2. Progress Bar Fill: anchored to the left edge and stretched vertically (anchor x 0..0, y 0..1).
+        //    sizeDelta.x is the fill width in units; Update sets it to BarWidth * progress.
         _progressBarFillObj = new GameObject("ProgressBarFill");
         _progressBarFillObj.transform.SetParent(_progressBarObj.transform, false);
         _progressBarFillObj.layer = 5;
@@ -123,7 +158,7 @@ internal class DebugMonitorUI : MonoBehaviour
         _fillRect.anchoredPosition = Vector2.zero;
         _fillRect.sizeDelta = new Vector2(0, 0); // width will be updated dynamically in Update()
 
-        // 3. Progress Bar Text
+        // 3. Progress Bar Text: centered over the whole bar
         var progressTextObj = new GameObject("ProgressBarText");
         progressTextObj.transform.SetParent(_progressBarObj.transform, false);
         progressTextObj.layer = 5;
@@ -135,7 +170,7 @@ internal class DebugMonitorUI : MonoBehaviour
         _progressText.font = ModAssets.NanumSquareNeoNormal;
         _progressText.color = BarTextColor;
 
-        // Add progress bar text outline for readability
+        // Black outline (90% opacity, 1.5-unit offset) keeps the white text readable over both the fill and the background
         var textOutline = progressTextObj.AddComponent<Outline>();
         textOutline.effectColor = new Color(0f, 0f, 0f, 0.9f);
         textOutline.effectDistance = new Vector2(1.5f, -1.5f);
@@ -147,10 +182,22 @@ internal class DebugMonitorUI : MonoBehaviour
         textRectBar.offsetMax = Vector2.zero;
     }
 
+    /// <summary>
+    /// Refreshes the statistics text and the progress bar from <see cref="RenderManager"/> and the game state.
+    /// Values fall back to 0 (and the queue limit to <c>RenderManager.MaxQueuedFrames</c>) when no RenderManager exists.
+    /// </summary>
     private void Update()
     {
         if (!_text) return;
 
+        // Statistics lines:
+        //   Queue            - frames waiting in ImageQueue for the render thread / queue frame limit
+        //   Rendered Frames  - RenderManager.frameCount (frames produced by the game)
+        //   Frames Sent      - RenderManager.framesSent (frames handed to the encoder; written by the render thread)
+        //   Throttling       - RenderManager.throttleCount (times the main Unity thread started waiting because ImageQueue
+        //                      held more frames than its limit)
+        //   Readback failures- RenderManager.readbackFailureCount (AsyncGPUReadback requests that completed with an error)
+        //   Mono heap        - GC.GetTotalMemory(false), managed heap size in MiB without forcing a collection
         var sb = new StringBuilder();
         sb.AppendLine("<b><color=#00ccff>ADOFAI Renderer Realtime Monitor</color></b>");
         sb.AppendLine();
@@ -158,6 +205,7 @@ internal class DebugMonitorUI : MonoBehaviour
         var queueCount = 0;
         if (RenderManager.Instance)
         {
+            // ImageQueue is shared with the render thread, so its count is read under the same lock
             lock (RenderManager.Instance.ImageQueue)
             {
                 queueCount = RenderManager.Instance.ImageQueue.Count;
@@ -177,7 +225,9 @@ internal class DebugMonitorUI : MonoBehaviour
 
         _text.text = sb.ToString();
 
-        // Update Progress Bar
+        // Update Progress Bar.
+        // progress = seqID of the current floor / index of the last floor (listFloors.Count - 1), clamped to 0..1.
+        // The text shows the percentage with one decimal and "(current / last)".
         var progress = 0f;
         var currentFloor = 0;
         var totalFloors = 0;

UI/EscapeHandlerUI.cs

@@ -6,15 +6,33 @@ using UnityEngine.UI;
 
 namespace ADOFAIRenderer.UI;
 
+/// <summary>
+/// Hold-Escape-to-cancel handler shown during a render.
+/// <para>
+/// Created by <c>RenderManager</c> when the render reaches the OnScene stage, on a GameObject kept across scene loads.
+/// While Escape is held, a centered panel shows a countdown from 3 seconds; holding it for the full 3 seconds
+/// (measured in real time with a <see cref="Stopwatch"/>, independent of the patched game time) calls
+/// <c>RenderManager.CancelRender</c>. Releasing Escape earlier hides the panel and resets the countdown.
+/// The component destroys its GameObject as soon as <c>RenderManager.IsActive</c> is false (stage below OnScene).
+/// Runs on the main Unity thread.
+/// </para>
+/// </summary>
 internal class EscapeHandlerUI : MonoBehaviour
 {
+    /// <summary>Centered countdown panel (background and text); inactive while Escape is not held.</summary>
     private GameObject _containerObj = null!;
+    /// <summary>Countdown text inside <see cref="_containerObj"/>.</summary>
     private TextMeshProUGUI _textComponent = null!;
+    /// <summary>Real-time hold duration of the current Escape press; <c>null</c> while Escape is not held.</summary>
     private Stopwatch? _escapeStopwatch;
 
+    /// <summary>
+    /// Builds the overlay canvas and the hidden countdown panel. Layout values are canvas units at the 1920x1080
+    /// reference resolution.
+    /// </summary>
     private void Start()
     {
-        // Set UI layer (5)
+        // Set UI layer (5, Unity's built-in "UI" layer)
         gameObject.layer = 5;
 
         // Canvas setup
@@ -22,7 +40,7 @@ internal class EscapeHandlerUI : MonoBehaviour
         canvas.renderMode = RenderMode.ScreenSpaceOverlay;
         canvas.sortingOrder = 10000; // Placed above debug monitor
 
-        // Responsive Canvas Scaler setup
+        // Canvas Scaler: 1920x1080 reference resolution, width and height matched equally (0.5)
         var scaler = gameObject.AddComponent<CanvasScaler>();
         scaler.uiScaleMode = CanvasScaler.ScaleMode.ScaleWithScreenSize;
         scaler.referenceResolution = new Vector2(1920, 1080);
@@ -31,7 +49,7 @@ internal class EscapeHandlerUI : MonoBehaviour
 
         gameObject.AddComponent<GraphicRaycaster>();
 
-        // 1. Create container and background panel object
+        // 1. Create container and background panel object: 460x160 units at the screen center
         _containerObj = new GameObject("EscapeContainer");
         _containerObj.transform.SetParent(transform, false);
         _containerObj.layer = 5;
@@ -46,7 +64,7 @@ internal class EscapeHandlerUI : MonoBehaviour
         containerRect.anchoredPosition = Vector2.zero; // Screen center
         containerRect.sizeDelta = new Vector2(460, 160);
 
-        // 2. Create text object
+        // 2. Create text object: 60 pt centered rich text, no wrapping, 10-unit margin inside the panel
         var textObj = new GameObject("EscapeText");
         textObj.transform.SetParent(_containerObj.transform, false);
         textObj.layer = 5;
@@ -57,7 +75,8 @@ internal class EscapeHandlerUI : MonoBehaviour
         _textComponent.textWrappingMode = TextWrappingModes.NoWrap;
         _textComponent.richText = true;
 
-        // Apply game's default font (RDString.fontData.fontTMP)
+        // Apply the game's TextMeshPro font for the current language (RDString.fontData.fontTMP, assigned in
+        // RDString.Setup). It is null before RDString.Setup has run; TextMeshPro's default font is kept then.
         if (RDString.fontData.fontTMP != null)
             _textComponent.font = RDString.fontData.fontTMP;
 
@@ -71,9 +90,13 @@ internal class EscapeHandlerUI : MonoBehaviour
         _containerObj.SetActive(false);
     }
 
+    /// <summary>
+    /// Tracks the Escape key every frame: shows and updates the countdown while it is held, cancels the render after
+    /// 3 seconds of holding, and hides the panel when it is released.
+    /// </summary>
     private void Update()
     {
-        // Destroy self if rendering is no longer active
+        // Destroy self once the render is inactive (stage below OnScene: finished, cancelled or failed)
         if (!RenderManager.IsActive)
         {
             Destroy(gameObject);
@@ -82,6 +105,7 @@ internal class EscapeHandlerUI : MonoBehaviour
 
         if (Input.GetKey(KeyCode.Escape))
         {
+            // First frame of the press: start timing and show the panel
             if (_escapeStopwatch == null)
             {
                 _escapeStopwatch = new Stopwatch();
@@ -92,13 +116,14 @@ internal class EscapeHandlerUI : MonoBehaviour
             var elapsed = (float)_escapeStopwatch.Elapsed.TotalSeconds;
             var remaining = Mathf.Max(0f, 3f - elapsed);
 
-            // Update remaining time text
+            // Update remaining time text (seconds, one decimal). The text is fixed English, not localized.
             _textComponent.text = $"<color=#FF5252>Cancelling in {remaining:F1}s..</color>\n<size=40><color=#DDDDDD>Hold Esc to cancel render</color></size>";
 
-            // Micro pulse animation (container smoothly scales up while holding)
+            // Grow animation: the panel scales linearly from 1.0 to 1.15 over the 3-second hold
             var scale = 1.0f + elapsed / 3.0f * 0.15f;
             _containerObj.transform.localScale = new Vector3(scale, scale, 1f);
 
+            // Held for the full 3 seconds: reset the panel, then cancel
             if (elapsed < 3f) return;
                 
             _escapeStopwatch.Stop();
@@ -106,12 +131,14 @@ internal class EscapeHandlerUI : MonoBehaviour
             _containerObj.transform.localScale = Vector3.one; // Reset scale
             _containerObj.SetActive(false);
 
-            // Cancel rendering and exit scene
+            // Cancel rendering: RenderManager.CancelRender resets the render state, stops the encoder as cancelled and
+            // ends the render. StopFFmpeg also destroys this handler's GameObject.
             if (RenderManager.Instance)
                 RenderManager.Instance.CancelRender();
         }
         else
         {
+            // Escape released before 3 seconds: stop timing and hide the panel
             if (_escapeStopwatch == null) return;
             _escapeStopwatch.Stop();
             _escapeStopwatch = null;
@@ -120,6 +147,7 @@ internal class EscapeHandlerUI : MonoBehaviour
         }
     }
 
+    /// <summary>Stops the hold stopwatch if a press is in progress.</summary>
     private void OnDestroy()
     {
         if (_escapeStopwatch == null) return;

UI/FFmpegDownloadUI.cs

@@ -15,27 +15,71 @@ using UnityEngine.UI;
 
 namespace ADOFAIRenderer.UI;
 
+/// <summary>
+/// Modal dialog that installs the FFmpeg shared libraries into MelonLoader's UserLibs folder.
+/// <para>
+/// Shown by <c>FirstUpdateHook</c> when <see cref="CheckFFmpegExists"/> reports missing libraries. On Windows and Linux
+/// the "Download" button downloads a prebuilt BtbN FFmpeg build (GPL, shared libraries) and extracts the libraries
+/// into UserLibs; on macOS the button opens https://ffmpeg.org, because the dialog text tells the user to build FFmpeg
+/// manually there. The libraries are found by FFmpeg.AutoGen through <c>ffmpeg.RootPath</c> (set to UserLibs in
+/// <c>RenderMod.OnInitializeMelon</c>).
+/// </para>
+/// <para>
+/// Threads: UI construction and all Unity object access happen on the main Unity thread. The download and extraction
+/// run on thread-pool threads (<see cref="Task.Run(Func{Task})"/>); they post UI updates to
+/// <see cref="_mainThreadQueue"/>, which <see cref="Update"/> drains on the main Unity thread.
+/// </para>
+/// <para>
+/// Flow: buttons -> (Download) progress bar + status text -> download to a temporary archive in UserLibs -> extract
+/// libraries -> "complete" for 1 second -> dialog destroyed. On failure the status shows the error and the buttons
+/// return so the user can retry or cancel. Cancel destroys the dialog at once and cancels a running download.
+/// </para>
+/// </summary>
 internal class FFmpegDownloadUI : MonoBehaviour
 {
+    /// <summary>Row with the Download/Open Website and Cancel buttons; hidden while a download runs.</summary>
     private GameObject _buttonContainerObj = null!;
+    /// <summary>Progress bar background (rounded, theme colors); shown when the download starts.</summary>
     private GameObject _progressBarObj = null!;
+    /// <summary>Progress bar fill object.</summary>
     private GameObject _progressBarFillObj = null!;
+    /// <summary>Fill rect; its <c>anchorMax.x</c> is the progress fraction 0..1 (see <see cref="UpdateProgress"/>).</summary>
     private RectTransform _fillRect = null!;
+    /// <summary>Text centered on the progress bar (percentage or "Extracting...").</summary>
     private TextMeshProUGUI _progressText = null!;
+    /// <summary>Status line below the progress bar; shown when the download starts.</summary>
     private GameObject _statusTextObj = null!;
+    /// <summary>Status message, colored by state (gray starting, cyan downloading, yellow extracting, green done, red failed).</summary>
     private TextMeshProUGUI _statusText = null!;
 
+    /// <summary>O5Kit window holding the dialog contents; disposed in <see cref="OnDestroy"/>.</summary>
     private O5Window? _window;
+    /// <summary>True from the Download click until the download fails; prevents a second concurrent download.</summary>
     private bool _isDownloading;
+
+    /// <summary>
+    /// Archive URL for the current platform: a fixed BtbN FFmpeg-Builds autobuild (2026-05-31, FFmpeg master
+    /// N-124714-g49a77d37be, GPL, shared libraries). Windows gets the win64 .zip; every other platform gets the
+    /// linux64 .tar.xz (macOS never downloads, see <see cref="Start"/>).
+    /// </summary>
     private string DownloadUrl => Application.platform switch
     {
         RuntimePlatform.WindowsPlayer => "https://github.com/BtbN/FFmpeg-Builds/releases/download/autobuild-2026-05-31-13-22/ffmpeg-N-124714-g49a77d37be-win64-gpl-shared.zip", 
         _ => "https://github.com/BtbN/FFmpeg-Builds/releases/download/autobuild-2026-05-31-13-22/ffmpeg-N-124714-g49a77d37be-linux64-gpl-shared.tar.xz"
     };
         
+    /// <summary>Cancellation for the running download; created per download, cancelled by Cancel, disposed in OnDestroy.</summary>
     private System.Threading.CancellationTokenSource? _cts;
+    /// <summary>Actions posted from background threads, run in order on the main Unity thread by <see cref="Update"/>.</summary>
     private readonly System.Collections.Concurrent.ConcurrentQueue<Action> _mainThreadQueue = new();
 
+    /// <summary>
+    /// Whether UserLibs contains at least one file for each of the five FFmpeg libraries the mod uses
+    /// (avcodec, avformat, avutil, swscale, swresample), matched by platform-specific file name patterns:
+    /// <c>avcodec-*.dll</c> on Windows, <c>libavcodec.*.dylib</c> on macOS, <c>libavcodec.so*</c> elsewhere.
+    /// Only file presence is checked, not the library version or whether it loads.
+    /// </summary>
+    /// <returns><c>false</c> when UserLibs does not exist or any library is missing.</returns>
     public static bool CheckFFmpegExists()
     {
         var userLibs = MelonEnvironment.UserLibsDirectory;
@@ -68,6 +112,10 @@ internal class FFmpegDownloadUI : MonoBehaviour
         return true;
     }
 
+    /// <summary>
+    /// Creates the dialog on a new GameObject kept across scene loads, unless the libraries are already present.
+    /// Main thread only.
+    /// </summary>
     public static void ShowDownloadUI()
     {
             
@@ -78,8 +126,13 @@ internal class FFmpegDownloadUI : MonoBehaviour
         obj.AddComponent<FFmpegDownloadUI>();
     }
 
+    /// <summary>
+    /// The open dialog, or <c>null</c> after it is destroyed. <c>FirstUpdateHook</c> waits while it is set and checks
+    /// the libraries again after it closes.
+    /// </summary>
     public static FFmpegDownloadUI? Instance { get; private set; }
 
+    /// <summary>Registers <see cref="Instance"/>; destroys the dialog again when the libraries already exist.</summary>
     private void Awake()
     {
         Instance = this;
@@ -89,9 +142,13 @@ internal class FFmpegDownloadUI : MonoBehaviour
         }
     }
 
+    /// <summary>
+    /// Builds the canvas, backdrop and window: description, button row, and the hidden progress bar and status line.
+    /// Layout values are canvas units at the 1920x1080 reference resolution.
+    /// </summary>
     private void Start()
     {
-        // Set UI layer (5)
+        // Set UI layer (5, Unity's built-in "UI" layer)
         gameObject.layer = 5;
             
         // Canvas setup
@@ -99,7 +156,7 @@ internal class FFmpegDownloadUI : MonoBehaviour
         canvas.renderMode = RenderMode.ScreenSpaceOverlay;
         canvas.sortingOrder = 32767; // Topmost
             
-        // Responsive Canvas Scaler setup
+        // Canvas Scaler: 1920x1080 reference resolution, width and height matched equally (0.5)
         var scaler = gameObject.AddComponent<CanvasScaler>();
         scaler.uiScaleMode = CanvasScaler.ScaleMode.ScaleWithScreenSize;
         scaler.referenceResolution = new Vector2(1920, 1080);
@@ -110,7 +167,7 @@ internal class FFmpegDownloadUI : MonoBehaviour
 
         var ctx = RendererUIManager.Context;
 
-        // 1. Create full screen backdrop
+        // 1. Create full screen backdrop: black at 65% opacity, blocks clicks to everything below
         var bgPanelObj = new GameObject("Backdrop");
         bgPanelObj.transform.SetParent(transform, false);
         bgPanelObj.layer = 5;
@@ -125,7 +182,8 @@ internal class FFmpegDownloadUI : MonoBehaviour
         bgRect.offsetMin = Vector2.zero;
         bgRect.offsetMax = Vector2.zero;
             
-        // 2. Create actual native O5Window
+        // 2. Create the O5Kit window: 580x270 units, draggable, fixed size, no close button (Cancel closes it).
+        //    The title is localized once here; the dialog does not follow later language changes.
         _window = O5Window.Create(ctx, bgPanelObj.transform, new O5WindowOptions
         {
             Id = "RendererMod_FFmpegDownloadDialog",
@@ -138,6 +196,8 @@ internal class FFmpegDownloadUI : MonoBehaviour
             Padding = new RectOffset(16, 16, 16, 16)
         });
 
+        // Vertical stack: description (takes the remaining height), buttons (40), progress bar (24), status (22),
+        // 14 units apart
         var content = _window.Content;
 
         var vLayout = content.gameObject.AddComponent<VerticalLayoutGroup>();
@@ -148,7 +208,7 @@ internal class FFmpegDownloadUI : MonoBehaviour
         vLayout.childForceExpandWidth = true;
         vLayout.childForceExpandHeight = false;
 
-        // 3. Description text
+        // 3. Description text: "required" line, then either the macOS build/website lines or the download/size lines
         var descText = O5Factory.ControlText(ctx, content, 18f, noPad: true);
         var descStrBuilder = new StringBuilder();
         descStrBuilder.AppendLine(LocalizationManager.Get("ui.ffmpeg_download.desc_required"));
@@ -172,7 +232,7 @@ internal class FFmpegDownloadUI : MonoBehaviour
         descLE.flexibleWidth = 1f;
         descLE.flexibleHeight = 1f;
 
-        // 4. Button container
+        // 4. Button container: two equal-width 40-unit buttons, 10 units apart
         _buttonContainerObj = new GameObject("ButtonContainer");
         _buttonContainerObj.transform.SetParent(content, false);
         _buttonContainerObj.layer = 5;
@@ -189,6 +249,7 @@ internal class FFmpegDownloadUI : MonoBehaviour
         btnLayout.childForceExpandWidth = true;
         btnLayout.childForceExpandHeight = true;
 
+        // Primary button: download and install (Windows/Linux), or open the FFmpeg website and close the dialog (macOS)
         Action onDownloadClick = Application.platform != RuntimePlatform.OSXPlayer 
             ? StartDownloadProcess 
             : () => { Application.OpenURL("https://ffmpeg.org"); Destroy(gameObject); };
@@ -220,7 +281,8 @@ internal class FFmpegDownloadUI : MonoBehaviour
         cancelBtnLE.flexibleWidth = 1f;
         cancelBtnLE.preferredHeight = 40f;
 
-        // 5. Progress bar container
+        // 5. Progress bar container (hidden until the download starts): rounded background in the theme object color
+        //    with a rounded outline drawn over it
         _progressBarObj = new GameObject("ProgressBarContainer");
         _progressBarObj.transform.SetParent(content, false);
         _progressBarObj.layer = 5;
@@ -251,7 +313,8 @@ internal class FFmpegDownloadUI : MonoBehaviour
         barOutlineRect.offsetMin = Vector2.zero;
         barOutlineRect.offsetMax = Vector2.zero;
 
-        // Progress bar fill image
+        // Progress bar fill image: anchored at the left edge with zero size offset, so its width is set entirely by
+        // anchorMax.x (0 = empty, 1 = full) in UpdateProgress
         _progressBarFillObj = new GameObject("ProgressBarFill");
         _progressBarFillObj.transform.SetParent(_progressBarObj.transform, false);
         _progressBarFillObj.layer = 5;
@@ -268,7 +331,7 @@ internal class FFmpegDownloadUI : MonoBehaviour
         _fillRect.anchoredPosition = Vector2.zero;
         _fillRect.sizeDelta = Vector2.zero;
 
-        // Progress text
+        // Progress text: 13 pt white, centered over the bar
         var progressTextObj = new GameObject("ProgressBarText");
         progressTextObj.transform.SetParent(_progressBarObj.transform, false);
         progressTextObj.layer = 5;
@@ -286,7 +349,7 @@ internal class FFmpegDownloadUI : MonoBehaviour
         progressTextRect.offsetMin = Vector2.zero;
         progressTextRect.offsetMax = Vector2.zero;
 
-        // 6. Status text
+        // 6. Status text (hidden until the download starts): 14 pt, centered
         _statusTextObj = new GameObject("StatusText");
         _statusTextObj.transform.SetParent(content, false);
         _statusTextObj.layer = 5;
@@ -310,20 +373,29 @@ internal class FFmpegDownloadUI : MonoBehaviour
         statusRect.offsetMax = Vector2.zero;
     }
 
+    /// <summary>Runs every action posted by the background download task, in posting order.</summary>
     private void Update()
     {
-        // Execute queued actions on main thread
+        // Execute queued actions on main Unity thread
         while (_mainThreadQueue.TryDequeue(out var action))
         {
             action?.Invoke();
         }
     }
 
+    /// <summary>
+    /// Posts an action to run on the main Unity thread during the next <see cref="Update"/>. Safe to call from any thread.
+    /// Actions posted after the dialog is destroyed are never run.
+    /// </summary>
     private void ExecuteOnMainThread(Action action)
     {
         _mainThreadQueue.Enqueue(action);
     }
 
+    /// <summary>
+    /// Download button handler (Windows/Linux): switches the dialog to progress mode and starts the background task
+    /// that downloads the archive, extracts the libraries and closes the dialog. Ignored while a download runs.
+    /// </summary>
     private void StartDownloadProcess()
     {
         if (_isDownloading) return;
@@ -336,7 +408,9 @@ internal class FFmpegDownloadUI : MonoBehaviour
 
         _cts = new System.Threading.CancellationTokenSource();
 
-        // Start download in background thread
+        // Start download in background thread. Everything inside runs on thread-pool threads: Unity objects are only
+        // touched through UpdateStatus/UpdateProgress/ExecuteOnMainThread. The task is not awaited; its outcome is
+        // reported through the status text.
         Task.Run(async () =>
         {
             string tempZipPath = "";
@@ -351,6 +425,8 @@ internal class FFmpegDownloadUI : MonoBehaviour
                     Directory.CreateDirectory(userLibsDir);
                 }
 
+                // Temporary archive path in UserLibs: ffmpeg_temp.zip (Windows, macOS) or ffmpeg_temp.tar.xz (others).
+                // It is deleted after extraction (ExtractDllsAsync) or on cancellation.
                 string extension = Application.platform switch
                 {
                     RuntimePlatform.WindowsPlayer => ".zip",
@@ -359,6 +435,8 @@ internal class FFmpegDownloadUI : MonoBehaviour
                 };
                 tempZipPath = Path.Combine(userLibsDir, "ffmpeg_temp" + extension);
                     
+                // percent is the downloaded fraction 0..1. Progress<T> created on a thread-pool thread (no
+                // SynchronizationContext) invokes this callback on thread-pool threads; it only posts UI updates.
                 var progressReporter = new Progress<float>(percent =>
                 {
                     UpdateProgress(percent, $"{percent * 100f:F1}%");
@@ -367,7 +445,7 @@ internal class FFmpegDownloadUI : MonoBehaviour
 
                 await DownloadFileAsync(DownloadUrl, tempZipPath, progressReporter, _cts.Token);
 
-                // Extract after download complete
+                // Extract after download complete; the bar is held at 99% while extracting
                 UpdateStatus(LocalizationManager.Get("ui.ffmpeg_download.status_extracting"), new Color(0.9f, 0.9f, 0.2f));
                 UpdateProgress(0.99f, LocalizationManager.Get("ui.ffmpeg_download.progress_extracting"));
 
@@ -377,9 +455,10 @@ internal class FFmpegDownloadUI : MonoBehaviour
                 UpdateStatus(LocalizationManager.Get("ui.ffmpeg_download.status_complete"), new Color(0.2f, 0.9f, 0.2f));
                 UpdateProgress(1f, "100%");
 
+                // Keep the "complete" message visible for 1000 ms before closing
                 await Task.Delay(1000);
 
-                // Destroy UI on main thread
+                // Destroy UI on main Unity thread. FirstUpdateHook then sees Instance == null and checks the libraries again.
                 ExecuteOnMainThread(() =>
                 {
                     Destroy(gameObject);
@@ -387,7 +466,8 @@ internal class FFmpegDownloadUI : MonoBehaviour
             }
             catch (OperationCanceledException)
             {
-                // Clean up temporary file on cancellation
+                // Clean up temporary file on cancellation. Cancellation comes from CancelProcess, which has already
+                // destroyed the dialog, so the status update below is posted but never shown.
                 if (!string.IsNullOrEmpty(tempZipPath) && File.Exists(tempZipPath))
                 {
                     try { File.Delete(tempZipPath); }
@@ -403,7 +483,9 @@ internal class FFmpegDownloadUI : MonoBehaviour
                 Melon<RenderMod>.Logger.Error($"Error during FFmpeg download/installation: {ex}");
                 UpdateStatus(LocalizationManager.Get("ui.ffmpeg_download.status_failed", ex.Message), new Color(1f, 0.3f, 0.3f));
                     
-                // Reset buttons on failure
+                // Reset buttons on failure so the user can retry (Download) or close the dialog (Cancel).
+                // The label is set to "Retry" only if a child at "DownloadButton/DownloadText" exists. The button made by
+                // O5Factory.Button in Start is a GameObject named "O5Button", which this path does not match.
                 ExecuteOnMainThread(() =>
                 {
                     _isDownloading = false;
@@ -418,6 +500,10 @@ internal class FFmpegDownloadUI : MonoBehaviour
         });
     }
 
+    /// <summary>
+    /// Cancel button handler: requests cancellation of a running download and destroys the dialog immediately.
+    /// An extraction already in progress is not cancellable and finishes in the background.
+    /// </summary>
     private void CancelProcess()
     {
         if (_isDownloading)
@@ -427,6 +513,7 @@ internal class FFmpegDownloadUI : MonoBehaviour
         Destroy(gameObject);
     }
 
+    /// <summary>Posts a status text and color change to the main Unity thread. Callable from any thread.</summary>
     private void UpdateStatus(string message, Color color)
     {
         ExecuteOnMainThread(() =>
@@ -439,6 +526,9 @@ internal class FFmpegDownloadUI : MonoBehaviour
         });
     }
 
+    /// <summary>Posts a progress bar update to the main Unity thread. Callable from any thread.</summary>
+    /// <param name="percent">Filled fraction 0..1 (not 0..100); becomes the fill's <c>anchorMax.x</c>.</param>
+    /// <param name="text">Text shown on the bar.</param>
     private void UpdateProgress(float percent, string text)
     {
         ExecuteOnMainThread(() =>
@@ -454,15 +544,28 @@ internal class FFmpegDownloadUI : MonoBehaviour
         });
     }
 
+    /// <summary>
+    /// Streams the HTTP response body of <paramref name="url"/> to <paramref name="destinationPath"/> (created or
+    /// overwritten) in 8 KiB chunks. Runs on a thread-pool thread.
+    /// </summary>
+    /// <param name="url">Archive URL.</param>
+    /// <param name="destinationPath">Output file path.</param>
+    /// <param name="progress">
+    /// Receives the downloaded fraction 0..1 after every chunk; not reported when the server sends no Content-Length.
+    /// </param>
+    /// <param name="cancellationToken">Cancels the request and the copy loop (<see cref="OperationCanceledException"/>).</param>
+    /// <exception cref="HttpRequestException">The server returned a non-success status code.</exception>
     private async Task DownloadFileAsync(string url, string destinationPath, IProgress<float> progress, System.Threading.CancellationToken cancellationToken)
     {
         using var client = new HttpClient();
-        // Add User-Agent header to prevent blocking
+        // Add User-Agent header to prevent blocking by servers that reject requests without one
         client.DefaultRequestHeaders.Add("User-Agent", "Mozilla/5.0 (Windows NT 10.0; Win64; x64) ADOFAIRenderer/1.0");
             
+        // ResponseHeadersRead returns after the headers, so the body is streamed instead of buffered in memory
         using var response = await client.GetAsync(url, HttpCompletionOption.ResponseHeadersRead, cancellationToken);
         response.EnsureSuccessStatusCode();
             
+        // Total size from Content-Length, or -1 when unknown. File stream: 8192-byte buffer, asynchronous I/O.
         var totalBytes = response.Content.Headers.ContentLength ?? -1L;
         await using var contentStream = await response.Content.ReadAsStreamAsync();
         await using var fileStream = new FileStream(destinationPath, FileMode.Create, FileAccess.Write, FileShare.None, 8192, true);
@@ -483,12 +586,28 @@ internal class FFmpegDownloadUI : MonoBehaviour
         }
     }
 
+    /// <summary>
+    /// Extracts the shared libraries from the downloaded archive into <paramref name="outputDirectory"/>, overwriting
+    /// files of the same name, and deletes the archive afterwards (also on failure; a failed delete is logged as a
+    /// warning). Runs on thread-pool threads and is not cancellable.
+    /// <list type="bullet">
+    /// <item>Windows/macOS (.zip): every entry ending in .dll (Windows) or .dylib (macOS) is extracted flat, by its file
+    /// name only, ignoring its folder inside the archive.</item>
+    /// <item>Other platforms (.tar.xz): the archive is unpacked with the system <c>tar</c> command into the temporary
+    /// folder "ffmpeg_temp_extracted" in <paramref name="outputDirectory"/>; every file matching <c>*.so*</c> in any
+    /// subfolder is copied flat to <paramref name="outputDirectory"/>, then the temporary folder is deleted.</item>
+    /// </list>
+    /// </summary>
+    /// <param name="zipPath">Downloaded archive path (.zip or .tar.xz despite the parameter name).</param>
+    /// <param name="outputDirectory">UserLibs folder.</param>
+    /// <exception cref="Exception"><c>tar</c> exited with a non-zero code (message includes its standard error).</exception>
     private async Task ExtractDllsAsync(string zipPath, string outputDirectory)
     {
         try
         {
             if (Application.platform == RuntimePlatform.OSXPlayer || Application.platform == RuntimePlatform.WindowsPlayer)
             {
+                // .zip: extract matching library entries flat into outputDirectory
                 await Task.Run(() =>
                 {
                     var targetExtension = Application.platform == RuntimePlatform.OSXPlayer ? ".dylib" : ".dll";
@@ -522,6 +641,7 @@ internal class FFmpegDownloadUI : MonoBehaviour
                     }
                     Directory.CreateDirectory(tempExtractDir);
 
+                    // tar receives forward-slash paths, quoted for spaces: tar -xf "<archive>" -C "<temp dir>"
                     var archiveUnixPath = zipPath.Replace('\\', '/');
                     var tempExtractUnixDir = tempExtractDir.Replace('\\', '/');
 
@@ -545,7 +665,8 @@ internal class FFmpegDownloadUI : MonoBehaviour
                         }
                     }
 
-                    // Find .so files and copy to outputDirectory
+                    // Find .so files (including versioned names such as libavcodec.so.<major>) and copy them flat to
+                    // outputDirectory
                     var soFiles = Directory.GetFiles(tempExtractDir, "*.so*", SearchOption.AllDirectories);
                     foreach (var soFile in soFiles)
                     {
@@ -582,6 +703,10 @@ internal class FFmpegDownloadUI : MonoBehaviour
         }
     }
 
+    /// <summary>
+    /// Disposes the window and the cancellation source and clears <see cref="Instance"/>. A download that was not
+    /// cancelled keeps running in the background; its UI updates are posted but no longer drained.
+    /// </summary>
     private void OnDestroy()
     {
         _window?.Dispose();

UI/LocalizedText.cs

@@ -8,15 +8,25 @@ namespace ADOFAIRenderer.UI;
 /// <summary>
 /// Component that binds a TextMeshProUGUI component to a localization key or dynamic string provider,
 /// automatically updating the displayed text whenever the active language changes.
+/// <para>
+/// The text is set when the binding is made (<see cref="Bind(TextMeshProUGUI, string)"/>), when the component is enabled,
+/// and on every <see cref="LocalizationManager.OnLanguageChanged"/> event. A key and a dynamic provider are mutually
+/// exclusive: setting one clears the other. With neither set, <see cref="Refresh"/> leaves the text unchanged.
+/// Runs on the main Unity thread.
+/// </para>
 /// </summary>
 internal class LocalizedText : MonoBehaviour
 {
+    /// <summary>Text component that receives the string; looked up on the same GameObject if not assigned by Bind.</summary>
     private TextMeshProUGUI? _textComponent;
+    /// <summary>Localization key resolved through <see cref="LocalizationManager.Get(string)"/>; <c>null</c> when a provider is used.</summary>
     private string? _key;
+    /// <summary>Function that returns the full text (already localized/formatted); <c>null</c> when a key is used.</summary>
     private Func<string>? _dynamicProvider;
 
     /// <summary>
-    /// Gets or sets the localization key. Setting this will clear any dynamic provider.
+    /// Gets or sets the localization key. Setting this will clear any dynamic provider and refresh the text immediately.
+    /// A null or empty key leaves the current text as it is.
     /// </summary>
     public string? Key
     {
@@ -30,8 +40,11 @@ internal class LocalizedText : MonoBehaviour
     }
 
     /// <summary>
-    /// Sets a dynamic string provider function.
+    /// Sets a dynamic string provider function, clears the key and refreshes the text immediately.
+    /// The provider is called on every refresh (enable and language change), so it can combine several keys or
+    /// runtime values, e.g. a label that depends on UI state.
     /// </summary>
+    /// <param name="provider">Function returning the text to display; called on the main Unity thread.</param>
     public void SetDynamic(Func<string> provider)
     {
         _dynamicProvider = provider;
@@ -39,27 +52,35 @@ internal class LocalizedText : MonoBehaviour
         Refresh();
     }
 
+    /// <summary>
+    /// Finds the text component and subscribes to language changes. The subscription lasts until <see cref="OnDestroy"/>,
+    /// also while the component is disabled (a refresh of a disabled object only changes its text).
+    /// </summary>
     private void Awake()
     {
         EnsureComponent();
         LocalizationManager.OnLanguageChanged += HandleLanguageChanged;
     }
 
+    /// <summary>Refreshes the text each time the component is enabled.</summary>
     private void OnEnable()
     {
         Refresh();
     }
 
+    /// <summary>Unsubscribes from <see cref="LocalizationManager.OnLanguageChanged"/>.</summary>
     private void OnDestroy()
     {
         LocalizationManager.OnLanguageChanged -= HandleLanguageChanged;
     }
 
+    /// <summary>Language change handler; the new language is read by <see cref="LocalizationManager.Get(string)"/>.</summary>
     private void HandleLanguageChanged(SystemLanguage language)
     {
         Refresh();
     }
 
+    /// <summary>Assigns <see cref="_textComponent"/> from the same GameObject if it is not set yet.</summary>
     private void EnsureComponent()
     {
         if (_textComponent == null)
@@ -70,6 +91,8 @@ internal class LocalizedText : MonoBehaviour
 
     /// <summary>
     /// Refreshes the text using either the dynamic provider or the static localization key.
+    /// The provider takes precedence; with neither set, or without a text component, nothing changes.
+    /// A key that is missing in every locale is displayed as the key itself (see <see cref="LocalizationManager.Get(string)"/>).
     /// </summary>
     public void Refresh()
     {
@@ -88,7 +111,13 @@ internal class LocalizedText : MonoBehaviour
 
     /// <summary>
     /// Binds a TextMeshProUGUI component to a localization key.
+    /// Reuses the <see cref="LocalizedText"/> already on the target's GameObject or adds one, then sets the key,
+    /// which replaces any earlier binding and updates the text immediately.
     /// </summary>
+    /// <param name="target">Text to localize.</param>
+    /// <param name="key">Localization key, e.g. <c>"ui.render_config.codec"</c>.</param>
+    /// <returns>The binding component.</returns>
+    /// <exception cref="ArgumentNullException"><paramref name="target"/> is null.</exception>
     public static LocalizedText Bind(TextMeshProUGUI target, string key)
     {
         if (target == null) throw new ArgumentNullException(nameof(target));
@@ -100,7 +129,12 @@ internal class LocalizedText : MonoBehaviour
 
     /// <summary>
     /// Binds a TextMeshProUGUI component to a dynamic string provider function.
+    /// Reuses or adds the component like <see cref="Bind(TextMeshProUGUI, string)"/> and updates the text immediately.
     /// </summary>
+    /// <param name="target">Text to localize.</param>
+    /// <param name="provider">Function returning the text; called on every refresh.</param>
+    /// <returns>The binding component.</returns>
+    /// <exception cref="ArgumentNullException"><paramref name="target"/> is null.</exception>
     public static LocalizedText Bind(TextMeshProUGUI target, Func<string> provider)
     {
         if (target == null) throw new ArgumentNullException(nameof(target));

UI/RendererUIManager.cs

@@ -8,9 +8,20 @@ namespace ADOFAIRenderer.UI;
 
 using UnityEngine;
 
+/// <summary>
+/// Assets loaded from the mod's embedded asset bundles (fonts and the color conversion compute shader).
+/// <para>
+/// <see cref="Load"/> is called once from <c>RenderMod.OnInitializeMelon</c>; the fields stay <c>null</c> until then.
+/// Bundles are obtained from <c>BundleLoader.GetBundle</c> by name ("fonts", "shaders"). Main thread only.
+/// </para>
+/// </summary>
 [SuppressMessage("ReSharper", "MemberCanBePrivate.Global")]
 internal static class ModAssets
 {
+    /// <summary>
+    /// Loads the font and shader bundles and the assets inside them, logging after each bundle.
+    /// Exceptions from bundle or asset loading are not caught here and propagate to the caller.
+    /// </summary>
     public static void Load()
     {
         FontBundle = BundleLoader.GetBundle("fonts");
@@ -23,24 +34,49 @@ internal static class ModAssets
         Melon<RenderMod>.Logger.Msg("Shader loaded successfully.");
     }
 
+    /// <summary>Asset bundle "fonts" holding the TextMeshPro font assets.</summary>
     public static AssetBundle FontBundle = null!;
+    /// <summary>Asset bundle "shaders" holding the compute shaders.</summary>
     public static AssetBundle ShaderBundle = null!;
 
+    /// <summary>
+    /// NanumSquare Neo, asset "NanumSquareNeoOTF-Bd SDF" (Bd = Bold weight). Used as the regular UI font of the mod
+    /// (O5Kit <see cref="RendererFontProvider.Regular"/>, DebugMonitorUI text).
+    /// </summary>
     public static TMP_FontAsset NanumSquareNeoNormal = null!;
+    /// <summary>
+    /// NanumSquare Neo, asset "NanumSquareNeoOTF-Eb SDF" (Eb = ExtraBold weight). Used as the O5Kit medium font
+    /// (<see cref="RendererFontProvider.Medium"/>).
+    /// </summary>
     public static TMP_FontAsset NanumSquareNeoBold = null!;
-    
+
+    /// <summary>
+    /// Compute shader "ColorConversion" that converts captured frames to the encoder's YUV pixel format on the GPU
+    /// (used by FrameReader).
+    /// </summary>
     public static ComputeShader ColorConversionShader = null!;
 }
 
+/// <summary>
+/// O5Kit font provider for the mod's UI: the bundled NanumSquare Neo fonts for regular and medium text, and O5Kit's
+/// default monospace font.
+/// </summary>
 internal sealed class RendererFontProvider : IFontProvider
 {
+    /// <summary>O5Kit default provider, used only for <see cref="Monospace"/>.</summary>
     private static readonly DefaultFontProvider DefaultFontProvider = new();
     private bool _disposed;
 
+    /// <summary>Regular text font: <see cref="ModAssets.NanumSquareNeoNormal"/>.</summary>
     public TMP_FontAsset Regular => ModAssets.NanumSquareNeoNormal;
+    /// <summary>Medium (emphasis) text font: <see cref="ModAssets.NanumSquareNeoBold"/>.</summary>
     public TMP_FontAsset Medium => ModAssets.NanumSquareNeoBold;
+    /// <summary>Monospace font (e.g. hex color input): O5Kit's default monospace font.</summary>
     public TMP_FontAsset Monospace => DefaultFontProvider.Monospace;
 
+    /// <summary>
+    /// Marks the provider disposed. The font assets belong to <see cref="ModAssets"/> and are not unloaded.
+    /// </summary>
     public void Dispose()
     {
         if (_disposed) return;
@@ -48,19 +84,39 @@ internal sealed class RendererFontProvider : IFontProvider
     }
 }
 
+/// <summary>
+/// Owner of the mod's O5Kit UI: the shared <see cref="O5Context"/> (config, theme, fonts) and the window manager
+/// with its canvas.
+/// <para>
+/// Added once by <c>RenderMod.OnInitializeMelon</c> to a GameObject kept across scene loads. Other UI code reads
+/// <see cref="Context"/> and <see cref="WindowManager"/> through the static <see cref="Instance"/>.
+/// <see cref="Update"/> drives O5Kit's per-frame work (object ticks, tooltip, keyboard shortcuts). Main thread only.
+/// </para>
+/// </summary>
 internal class RendererUIManager : MonoBehaviour
 {
+    /// <summary>The single instance, assigned in <see cref="Awake"/>.</summary>
     public static RendererUIManager Instance = null!;
 
+    /// <summary>Shared O5Kit context used to build every mod window and dialog.</summary>
     public static O5Context Context => Instance._context;
+    /// <summary>Window manager whose canvas holds the mod windows (e.g. RenderConfigWindow).</summary>
     public O5WindowManager WindowManager => _windowManager;
 
     private O5Context _context = null!;
     private O5WindowManager _windowManager = null!;
 
+    /// <summary>
+    /// Creates the O5Kit context with the mod theme and fonts, then the window manager and its canvas
+    /// ("RendererMod_Canvas"), and lowers that canvas's sorting order to <see cref="WindowCanvasSortingOrder"/>.
+    /// </summary>
     private void Awake() {
         Instance = this;
-        
+
+        // O5Kit config: UI scale 1.0, middle click resets a control to its default value, slider drag sensitivity 1.0.
+        // Theme: O5Kit's dark theme with the mod colors. Colors are RGBA 0..1; the accent color
+        // (1.000, 0.294, 0.079) is orange-red (#FF4B14 approx.). Sizes are canvas units: corner radius 12,
+        // outline width 2, control height 40, body font 18, H1 font 48.
         _context = new O5Context(
             config: new O5Config {
                 UIScale = 1.0f,
@@ -101,14 +157,20 @@ internal class RendererUIManager : MonoBehaviour
         if (windowCanvas != null) windowCanvas.sortingOrder = WindowCanvasSortingOrder;
     }
     
+    /// <summary>
+    /// Sorting order of the window canvas: below CommonWarningDialogUI (32766) and FFmpegDownloadUI (32767), above the
+    /// render overlays (DebugMonitorUI 9999, EscapeHandlerUI 10000).
+    /// </summary>
     private const int WindowCanvasSortingOrder = 32000;
 
+    /// <summary>Runs O5Kit's per-frame updates: object ticks, tooltip, and keyboard shortcut handling.</summary>
     private void Update() {
         O5Object.TickAll();
         Context.Tooltip.Tick();
         O5Kit.Input.O5ShortcutManager.HandleUpdate();
     }
     
+    /// <summary>Disposes the window manager, then the context.</summary>
     private void OnDestroy() {
         _windowManager.Dispose();
         _context.Dispose();

Util/Audio/AudioSpectrumGenerator.cs

@@ -28,14 +28,31 @@ internal static class AudioSpectrumGenerator
     /// </summary>
     private const double MonoGain = 0.70710678118654752;
 
+    /// <summary>Store created by this class when the mixer store cannot be shared (disposed by <see cref="Clear"/>); otherwise null.</summary>
     private static AudioClipStore? _ownStore;
+
+    /// <summary>Store the song source belongs to: the mixer store or <see cref="_ownStore"/>.</summary>
     private static AudioClipStore? _store;
+
+    /// <summary>Song source at the output sample rate, or null when not initialized or the song could not be loaded.</summary>
     private static AudioClipSource? _source;
+
+    /// <summary>Cursor on <see cref="_source"/> moved to each analysis window, so the decoder thread loads the chunks there.</summary>
     private static AudioCursor? _cursor;
+
+    /// <summary>Chunk currently held for <see cref="ReadSample"/> (invalid when none).</summary>
     private static ChunkView _view;
+
+    /// <summary>True after a chunk loading error was logged (logged once per render).</summary>
     private static bool _loadErrorLogged;
 
+    /// <summary>RenderManager.frameCount of the spectra in <see cref="CachedSpectrums"/>; -1 when empty.</summary>
     private static long _cachedFrame = -1;
+
+    /// <summary>
+    /// Spectra computed in the current render frame, by spectrum length and source channel. Several game objects read the
+    /// spectrum every frame; within one frame the render time does not change, so they receive the same values.
+    /// </summary>
     private static readonly Dictionary<(int Size, int Channel), float[]> CachedSpectrums = new();
 
     /// <summary>Registers the song clip. Call after the <see cref="OfflineAudioMixer"/> is created (null when audio is not rendered).</summary>
@@ -93,6 +110,17 @@ internal static class AudioSpectrumGenerator
         CachedSpectrums.Clear();
     }
 
+    /// <summary>
+    /// Fills <paramref name="samples"/> with the magnitude spectrum of the song at the current render time
+    /// (called by the AudioSource.GetSpectrumData patch while capturing with ProcessAudio on, for any AudioSource).
+    /// Bin k covers frequency k * outputRate / (2 * samples.Length) Hz in output time; values are 0 ~ 1.
+    /// Zeros are written when the song is not available, the conductor has not started the song, or the length is not a power of two.
+    /// <paramref name="window"/> is not read: the Blackman-Harris window is always used (every GetSpectrumData call in the game
+    /// passes FFTWindow.BlackmanHarris). Main thread only.
+    /// </summary>
+    /// <param name="samples">Destination; its length is the spectrum length (power of two).</param>
+    /// <param name="channel">Requested channel (0 = left, 1 = right), clamped to the song's channels; ignored for mono songs.</param>
+    /// <param name="window">Requested window (not used).</param>
     public static void GetSpectrumData(float[] samples, int channel, FFTWindow window)
     {
         var n = samples.Length;
@@ -127,6 +155,8 @@ internal static class AudioSpectrumGenerator
         var now = render.dspTimeBase + render.AudioTime;
         var songSeconds = (now - conductor.dspTimeSong) * pitch - countdown;
 
+        // Window of 2n output samples centered on the current time: output sample i reads source frame first + i * pitch,
+        // so the window starts n output samples (n * pitch source frames) before the song position.
         var fftSize = 2 * n;
         var gain = volume * (_source.Channels == 1 ? MonoGain : 1.0);
         var first = songSeconds * _store.OutputRate - n * pitch;
@@ -134,6 +164,7 @@ internal static class AudioSpectrumGenerator
         var windowSamples = new float[fftSize];
         try
         {
+            // Keep the cursor at the window start so the decoder thread loads (and keeps) the chunks the window reads.
             _cursor!.Position = Math.Min(Math.Max((long)first, 0), _source.TotalFrames - 1);
             for (var i = 0; i < fftSize; i++)
             {
@@ -178,6 +209,10 @@ internal static class AudioSpectrumGenerator
         return _view.Data[(int)(frame - _view.StartFrame) * _view.Channels + channel];
     }
 
+    /// <summary>
+    /// Magnitude spectrum of <paramref name="samples"/> (length n, a power of two) after the Blackman-Harris window:
+    /// writes min(n / 2, spectrum.Length) bins, bin k = min(|X[k]| * 2.5 / n, 1).
+    /// </summary>
     private static void CalculateFFT(float[] samples, float[] spectrum)
     {
         var n = samples.Length;
@@ -199,10 +234,10 @@ internal static class AudioSpectrumGenerator
             im[i] = 0f;
         }
 
-        // Cooley-Tukey Radix-2 FFT
+        // Cooley-Tukey Radix-2 FFT (iterative, in place, decimation in time); m = log2(n) stages.
         var m = (int)Math.Round(Math.Log(n, 2));
 
-        // Bit-reversal
+        // Bit-reversal: reorder the input so element i moves to the index with the bits of i reversed (j tracks that index).
         var j = 0;
         for (var i = 0; i < n - 1; i++)
         {
@@ -225,7 +260,8 @@ internal static class AudioSpectrumGenerator
             j += k;
         }
 
-        // FFT stages
+        // FFT stages: stage s combines pairs of transforms of length le/2 into length le = 2^s with butterflies.
+        // (ur, ui) is the twiddle factor exp(-i * pi * sub / le2), advanced by multiplying with (wr, wi) = exp(-i * pi / le2).
         for (var stage = 1; stage <= m; stage++)
         {
             var le = 1 << stage;

Util/Audio/AudioSyncCalculator.cs

@@ -2,29 +2,50 @@ using System;
 
 namespace ADOFAIRenderer.Util.Audio;
 
+/// <summary>
+/// Splits the audio sample stream into per-video-frame sample counts so that audio and video stay aligned without drift.
+///
+/// The frame rate is converted to an exact fraction Numerator / Denominator (<see cref="RationalUtil.Double2MaxPrecisionInt"/>).
+/// Frame k receives floor((k + 1) * sampleRate * Denominator / Numerator) - floor(k * sampleRate * Denominator / Numerator) samples:
+/// the remainder of each division is carried into the next frame, so the sum over any number of frames equals the exact
+/// sample count of that duration rounded down (for example 44100 Hz at 60 FPS gives 735 every frame; at 144 FPS three frames of 306
+/// are followed by one of 307, 306.25 on average).
+/// Used by the render thread only (RenderManager.WriteAudioForFrame, once per frame sent to the encoder).
+/// </summary>
 internal class AudioSyncCalculator
 {
+    /// <summary>Audio sample rate in Hz (samples per channel per second).</summary>
     private readonly long _sampleRate;
+
+    /// <summary>Video frame rate as a fraction (frames per second = Numerator / Denominator).</summary>
     private readonly (long Numerator, long Denominator) _fpsRational;
 
+    /// <summary>Total samples handed out since construction or <see cref="Reset"/> (kept for debugging, not read).</summary>
     // ReSharper disable once NotAccessedField.Local
     private long _currentSample;
+
+    /// <summary>Remainder of the last division, in units of 1 / Numerator samples (0 ~ Numerator - 1).</summary>
     private long _remainder;
         
+    /// <param name="sampleRate">Audio sample rate in Hz.</param>
+    /// <param name="fps">Video frame rate in frames per second (the encoded frame rate).</param>
     public AudioSyncCalculator(long sampleRate, double fps)
     {
         _sampleRate = sampleRate;
         _fpsRational = RationalUtil.Double2MaxPrecisionInt(fps);
     }
 
+    /// <summary>Restarts the sequence at frame 0 (the remainder is cleared).</summary>
     public void Reset()
     {
         _currentSample = 0;
         _remainder = 0;
     }
 
+    /// <summary>Returns the sample count (frames per channel) of the next video frame and advances to the following frame.</summary>
     public int GetNextFrameSamples()
     {
+        // samplesNeeded = floor((sampleRate * Denominator + remainder) / Numerator); the new remainder carries the fraction.
         var numerator = _sampleRate * _fpsRational.Denominator + _remainder;
         var samplesNeeded = numerator / _fpsRational.Numerator;
 

Util/Audio/Clip/AudioClipPaths.cs

@@ -20,6 +20,7 @@ internal static class AudioClipPaths
     /// <summary>Suffix of the game's audioLib keys for external clips.</summary>
     public const string ExternalSuffix = "*external";
 
+    /// <summary>File path by audioLib key; also the lock object. Entries are kept for the whole game session.</summary>
     private static readonly Dictionary<string, string> Paths = new();
 
     /// <summary>audioLib key of an external clip loaded from <paramref name="path"/>.</summary>

Util/Audio/Clip/AudioClipResolver.cs

@@ -16,6 +16,10 @@ namespace ADOFAIRenderer.Util.Audio.Clip;
 /// </summary>
 internal static class AudioClipResolver
 {
+    /// <summary>
+    /// Returns the source registered under <paramref name="key"/> in <paramref name="store"/>, opening it on first use
+    /// (file first, then the Unity clip; see the class summary). A key that could not be opened is remembered as null.
+    /// </summary>
     /// <param name="store">Store of the current render.</param>
     /// <param name="key">audioLib key of the clip (for example "song.ogg*external" or "sndKick").</param>
     /// <param name="clip">Loaded Unity clip for the key, used when the clip has no file; may be null when the key has a file.</param>
@@ -38,6 +42,9 @@ internal static class AudioClipResolver
                 Melon<RenderMod>.Logger.Warning($"[AudioClipResolver] FFmpeg could not open '{path}' for '{key}', using the Unity clip: {e.Message}");
             }
 
+            // The reader opened here becomes the first decode stream; additional streams reopen the file with OpenFile.
+            // When no source results (store disposed, or the source could not be created), the reader is disposed here
+            // (readers allow Dispose more than once).
             if (fileReader != null)
             {
                 var source = store.GetOrAdd(key, () => fileReader, () => OpenFile(path));

Util/Audio/Clip/AudioClipSource.cs

@@ -13,9 +13,13 @@ namespace ADOFAIRenderer.Util.Audio.Clip;
 internal sealed class AudioCursor
 {
     private readonly AudioClipSource _source;
+
+    /// <summary>Backing value of <see cref="Position"/>, accessed with Interlocked (64-bit reads are not atomic on every platform).</summary>
     private long _position;
+
     private volatile bool _loop;
 
+    /// <summary>Created by <see cref="AudioClipSource.AddCursor"/>.</summary>
     internal AudioCursor(AudioClipSource source, long position, bool loop)
     {
         _source = source;
@@ -39,7 +43,10 @@ internal sealed class AudioCursor
         }
     }
 
-    /// <summary>When true, the chunk after the last chunk is chunk 0.</summary>
+    /// <summary>
+    /// When true, the chunk after the last chunk is chunk 0 (the window wraps to the clip start), and a position past the end
+    /// wraps into the clip. Setting it wakes the decoder thread.
+    /// </summary>
     public bool Loop
     {
         get => _loop;
@@ -70,8 +77,10 @@ internal readonly struct ChunkView
     /// <summary>Channel count of the stored samples (same as the source clip).</summary>
     public readonly int Channels;
 
+    /// <summary>Index of the chunk in its source (used by <see cref="AudioClipSource.Release"/>).</summary>
     public readonly int ChunkIndex;
 
+    /// <summary>Created by <see cref="AudioClipSource.TryAcquire"/>; default(ChunkView) is the invalid view.</summary>
     internal ChunkView(float[] data, long startFrame, int frameCount, int channels, int chunkIndex)
     {
         Data = data;
@@ -81,10 +90,13 @@ internal readonly struct ChunkView
         ChunkIndex = chunkIndex;
     }
 
+    /// <summary>True for a view that holds a chunk; false for default(ChunkView).</summary>
     public bool IsValid => Data != null;
 
+    /// <summary>Source frame after the last valid frame (exclusive end).</summary>
     public long EndFrame => StartFrame + FrameCount;
 
+    /// <summary>True when source frame <paramref name="frame"/> is one of the valid frames of this chunk.</summary>
     public bool Contains(long frame) => frame >= StartFrame && frame < StartFrame + FrameCount;
 
     /// <summary>
@@ -163,7 +175,7 @@ internal sealed class AudioClipSource
     /// <summary>
     /// Most decode streams (reader + resampler) a windowed source opens. A load continues the stream positioned at the chunk start,
     /// otherwise opens another stream up to this count, otherwise restarts the least recently used stream.
-    /// Each stream holds one open reader (file handle and decoder state, measured 0.3 ~ 2.7 MiB for ogg/flac/mp3 with the clip harness).
+    /// Each stream holds one open reader (file handle and decoder state, measured 0.3 ~ 2.7 MiB for ogg/flac/MP3 with the clip harness).
     /// </summary>
     public const int MaxDecodeStreams = 4;
 
@@ -171,26 +183,45 @@ internal sealed class AudioClipSource
     internal int DecodeStreamLimit { get; set; } = MaxDecodeStreams;
 
     private readonly AudioClipStore _store;
+
+    /// <summary>Reader passed to the constructor (the first decode stream); disposed again in <see cref="DisposeInternal"/>.</summary>
     private readonly IPCMReader _firstReader;
+
+    /// <summary>Opens another reader for an additional decode stream; null when only the first reader can be used.</summary>
     private readonly Func<IPCMReader?>? _openReader;
 
     // Guarded by _sync: chunk table, hold counts, cursors, demand set, loaded set.
     private readonly object _sync = new();
+
+    /// <summary>Sample array of each chunk, null while not loaded.</summary>
     private readonly float[]?[] _chunks;
+
+    /// <summary>Number of consumers holding each chunk (TryAcquire minus Release); a held chunk is not freed.</summary>
     private readonly int[] _holdCounts;
+
     private readonly List<AudioCursor> _cursors = new();
+
+    /// <summary>Chunks a consumer asked for while they were not loaded; an index is removed when the chunk is acquired.</summary>
     private readonly HashSet<int> _demanded = new();
+
+    /// <summary>Indices of the loaded chunks (non-null entries of <see cref="_chunks"/>).</summary>
     private readonly HashSet<int> _loaded = new();
+
     private int _residentLoadedCount; // Resident: chunks [0, _residentLoadedCount) are loaded
 
     // Guarded by _loadLock: decode streams.
     private readonly object _loadLock = new();
     private readonly List<DecodeStream> _streams = new();
+
+    /// <summary>Incremented on every load; stored in <see cref="DecodeStream.LastUse"/> for least-recently-used selection.</summary>
     private long _streamUseCounter;
+
+    /// <summary>True after opening an additional reader failed; no further readers are opened for this source.</summary>
     private bool _openFailed;
 
     private volatile bool _isFailed;
 
+    /// <summary>Key the source is registered under in the store (the game's audioLib key / AudioClip.name).</summary>
     public string Key { get; }
 
     /// <summary>Channel count of the stored samples (same as the clip).</summary>
@@ -205,12 +236,19 @@ internal sealed class AudioClipSource
     /// <summary>Clip length in seconds: clip frames / clip rate.</summary>
     public double Duration { get; }
 
+    /// <summary>Frames per chunk: <see cref="ChunkFloats"/> / <see cref="Channels"/> (rounded down).</summary>
     public int FramesPerChunk { get; }
 
+    /// <summary>Number of chunks: ceil(<see cref="TotalFrames"/> / <see cref="FramesPerChunk"/>); 0 for an empty clip.</summary>
     public int ChunkCount { get; }
 
+    /// <summary>
+    /// <see cref="ChunkPolicy.Resident"/> for forward-only readers and clips of at most one chunk, otherwise
+    /// <see cref="ChunkPolicy.Windowed"/>. Fixed at construction.
+    /// </summary>
     public ChunkPolicy Policy { get; }
 
+    /// <summary>True when <see cref="Policy"/> is <see cref="ChunkPolicy.Resident"/>.</summary>
     public bool IsResident => Policy == ChunkPolicy.Resident;
 
     /// <summary>True after loading failed. A failed source returns no chunks.</summary>
@@ -279,6 +317,7 @@ internal sealed class AudioClipSource
         return cursor;
     }
 
+    /// <summary>Unregisters <paramref name="cursor"/>; its window chunks become freeable on the decoder thread's next pass.</summary>
     public void RemoveCursor(AudioCursor cursor)
     {
         lock (_sync)
@@ -288,6 +327,7 @@ internal sealed class AudioClipSource
         _store.RequestService();
     }
 
+    /// <summary>Wakes the decoder thread after a cursor changed chunk or loop flag (resident sources ignore cursors).</summary>
     internal void OnCursorMoved()
     {
         if (!IsResident) _store.RequestService();
@@ -325,6 +365,7 @@ internal sealed class AudioClipSource
         return false;
     }
 
+    /// <summary>Ends one hold of the chunk of <paramref name="view"/> taken by <see cref="TryAcquire"/>. An invalid view is ignored.</summary>
     public void Release(in ChunkView view)
     {
         if (!view.IsValid) return;
@@ -335,6 +376,7 @@ internal sealed class AudioClipSource
         }
     }
 
+    /// <summary>View of chunk <paramref name="index"/>; the last chunk's frame count stops at <see cref="TotalFrames"/>.</summary>
     private ChunkView CreateView(int index, float[] data)
     {
         var start = (long)index * FramesPerChunk;
@@ -406,6 +448,8 @@ internal sealed class AudioClipSource
                 return true;
             }
 
+            // For each cursor, the first missing chunk of its window; the lowest slot over all cursors wins
+            // (ties go to the earlier cursor).
             foreach (var cursor in _cursors)
             {
                 if (!TryGetWindowStart(cursor, out var first, out var loop)) continue;
@@ -441,6 +485,10 @@ internal sealed class AudioClipSource
         return false;
     }
 
+    /// <summary>
+    /// First chunk of the cursor's window: the chunk of its position (negative positions count as 0; positions past the end
+    /// wrap when looping). False when a non-looping cursor is past the end (no window). Caller holds _sync.
+    /// </summary>
     private bool TryGetWindowStart(AudioCursor cursor, out int first, out bool loop)
     {
         var position = cursor.Position;
@@ -456,6 +504,7 @@ internal sealed class AudioClipSource
         return true;
     }
 
+    /// <summary>Chunk index of window slot <paramref name="slot"/> after <paramref name="first"/>; wraps when looping, false past the end otherwise.</summary>
     private bool TryWindowIndex(int first, int slot, bool loop, out int index)
     {
         index = first + slot;
@@ -493,6 +542,7 @@ internal sealed class AudioClipSource
                 stream.LastUse = ++_streamUseCounter;
                 stream.Fill(start, frames, data);
             }
+            // Out of memory fails the whole render (store fatal error); any other error makes only this source silent.
             catch (OutOfMemoryException e)
             {
                 ReturnArray(data);
@@ -568,12 +618,14 @@ internal sealed class AudioClipSource
         return oldest!;
     }
 
+    /// <summary>Marks the source failed (no more chunks are returned or loaded); a resident source also closes its readers now. Caller holds _loadLock.</summary>
     private void Fail()
     {
         _isFailed = true;
         if (IsResident) DisposeStreams();
     }
 
+    /// <summary>Disposes every decode stream (reader and resampler) and clears the list. Caller holds _loadLock.</summary>
     private void DisposeStreams()
     {
         foreach (var stream in _streams)
@@ -581,6 +633,7 @@ internal sealed class AudioClipSource
         _streams.Clear();
     }
 
+    /// <summary>Gives a chunk array back to the store: exact arrays (resident) are uncounted, pooled arrays (windowed) are returned to the pool.</summary>
     private void ReturnArray(float[]? data)
     {
         if (data == null) return;
@@ -609,5 +662,6 @@ internal sealed class AudioClipSource
         }
     }
 
+    /// <summary>ceil(a / b) for a ≥ 0, b &gt; 0.</summary>
     private static long CeilDiv(long a, long b) => (a + b - 1) / b;
 }

Util/Audio/Clip/AudioClipStore.cs

@@ -12,7 +12,7 @@ namespace ADOFAIRenderer.Util.Audio.Clip;
 /// - Decoder thread (<see cref="Start"/>): the only thread that decodes, resamples, loads and frees chunks.
 ///   Each step loads one chunk, the one with the lowest priority value over all sources
 ///   (a chunk a consumer waits for, then cursor windows by slot, then resident chunks in order).
-/// - Consumers (render thread, main thread for the spectrum): <see cref="Acquire"/> waits for the decoder thread and never loads.
+/// - Consumers (render thread, main Unity thread for the spectrum): <see cref="Acquire"/> waits for the decoder thread and never loads.
 /// - Main thread: <see cref="GetOrAdd"/> creates readers (for Unity clips this copies the clip data).
 ///
 /// Memory has no limit; current and peak usage are tracked and logged by <see cref="LogMemoryUsage"/>.
@@ -29,18 +29,34 @@ internal sealed class AudioClipStore : IDisposable
     /// <summary>Longest wait for the decoder thread to stop in <see cref="Dispose"/>, in milliseconds.</summary>
     private const int DecoderStopTimeoutMs = 3000;
 
+    /// <summary>Sources by key; a null value marks a key whose reader could not be created. Also the lock of the source tables.</summary>
     private readonly Dictionary<string, AudioClipSource?> _sources = new();
+
+    /// <summary>Non-null sources in creation order, scanned by the decoder thread. Guarded by the <see cref="_sources"/> lock.</summary>
     private readonly List<AudioClipSource> _sourceList = new();
+
+    /// <summary>Free windowed chunk arrays (<see cref="AudioClipSource.ChunkFloats"/> floats each), guarded by <see cref="_poolLock"/>.</summary>
     private readonly Stack<float[]> _chunkPool = new();
+
     private readonly object _poolLock = new();
+
+    /// <summary>Monitor the decoder thread pulses after each load (or failure); consumers in <see cref="Acquire"/> wait on it.</summary>
     private readonly object _signal = new();
+
+    /// <summary>Wakes the decoder thread when a cursor, demand or source changes (<see cref="RequestService"/>).</summary>
     private readonly AutoResetEvent _serviceRequested = new(false);
 
     private Thread? _decoderThread;
     private volatile bool _stopRequested;
+
+    /// <summary>Bytes of allocated sample arrays (see <see cref="AllocatedBytes"/>), updated with Interlocked.</summary>
     private long _allocatedBytes;
+
     private long _peakBytes;
+
+    /// <summary>First fatal error (out of memory, or an exception that stopped the decoder thread); null while none.</summary>
     private volatile Exception? _fatalError;
+
     private volatile bool _disposed;
 
     /// <summary>Sample rate every source is resampled to, in Hz.</summary>
@@ -52,9 +68,12 @@ internal sealed class AudioClipStore : IDisposable
     /// <summary>Highest value of <see cref="AllocatedBytes"/> since creation.</summary>
     public long PeakBytes => Interlocked.Read(ref _peakBytes);
 
-    /// <summary>Out-of-memory error raised while loading, or null.</summary>
+    /// <summary>
+    /// Out-of-memory error raised while opening or loading a clip, or the exception that stopped the decoder thread; null while none.
+    /// </summary>
     public Exception? FatalError => _fatalError;
 
+    /// <param name="outputRate">Sample rate in Hz every source is resampled to (positive). Call <see cref="Start"/> to begin decoding.</param>
     public AudioClipStore(int outputRate)
     {
         if (outputRate <= 0) throw new ArgumentOutOfRangeException(nameof(outputRate));
@@ -75,6 +94,11 @@ internal sealed class AudioClipStore : IDisposable
         _decoderThread.Start();
     }
 
+    /// <summary>
+    /// Decoder thread body: loads one chunk per iteration, or sleeps until <see cref="RequestService"/> (at most
+    /// <see cref="DecoderIdleWaitMs"/> ms) when nothing is missing. An unexpected exception ends the thread and is kept as the
+    /// fatal error, so waiting consumers fail instead of waiting forever.
+    /// </summary>
     private void DecoderLoop()
     {
         try
@@ -124,6 +148,7 @@ internal sealed class AudioClipStore : IDisposable
         return true;
     }
 
+    /// <summary>Wakes the decoder thread to re-evaluate what to free and load. Any thread.</summary>
     internal void RequestService() => _serviceRequested.Set();
 
     // ── Sources ──
@@ -169,6 +194,8 @@ internal sealed class AudioClipStore : IDisposable
             Melon<RenderMod>.Logger.Error($"[AudioClipStore] Failed to open clip '{key}': {e}");
         }
 
+        // The reader is created outside the lock (it may decode or copy a whole clip). If another caller registered the
+        // same key meanwhile, its entry wins and this source is discarded.
         lock (_sources)
         {
             if (_disposed || _sources.TryGetValue(key, out var raced))
@@ -188,6 +215,10 @@ internal sealed class AudioClipStore : IDisposable
         return source;
     }
 
+    /// <summary>
+    /// True when <paramref name="key"/> has been registered; <paramref name="source"/> is then the source, or null when its reader
+    /// could not be created. Any thread.
+    /// </summary>
     public bool TryGet(string key, out AudioClipSource? source)
     {
         lock (_sources)
@@ -214,6 +245,8 @@ internal sealed class AudioClipStore : IDisposable
             if (source.IsFailed || _disposed) return default;
             if (source.TryAcquire(frame, out var view)) return view;
 
+            // Retry under the signal lock so a load completed between the first try and the wait is not missed;
+            // the timed wait also rechecks cancellation and failure states periodically.
             lock (_signal)
             {
                 if (source.TryAcquire(frame, out view)) return view;
@@ -224,6 +257,7 @@ internal sealed class AudioClipStore : IDisposable
         }
     }
 
+    /// <summary>Throws <see cref="InvalidOperationException"/> wrapping <see cref="FatalError"/> when one is set.</summary>
     private void ThrowIfFatal()
     {
         var error = _fatalError;
@@ -231,6 +265,7 @@ internal sealed class AudioClipStore : IDisposable
             throw new InvalidOperationException("Audio clip loading failed: " + error.Message, error);
     }
 
+    /// <summary>Wakes every consumer waiting in <see cref="Acquire"/> (after a load, a failure, or on dispose).</summary>
     internal void NotifyChunkLoaded()
     {
         lock (_signal)
@@ -239,12 +274,14 @@ internal sealed class AudioClipStore : IDisposable
         }
     }
 
+    /// <summary>Logs a load error of one source (the source is already marked failed and plays silence) and wakes waiting consumers.</summary>
     internal void ReportSourceFailure(AudioClipSource source, Exception error)
     {
         Melon<RenderMod>.Logger.Error($"[AudioClipStore] Failed to load clip '{source.Key}', it will be silent: {error}");
         NotifyChunkLoaded();
     }
 
+    /// <summary>Logs an out-of-memory error, keeps it as <see cref="FatalError"/> (first one wins) and wakes waiting consumers.</summary>
     internal void ReportFatal(AudioClipSource source, OutOfMemoryException error)
     {
         Melon<RenderMod>.Logger.Error($"[AudioClipStore] Out of memory while loading clip '{source.Key}' ({AllocatedBytes / 1048576.0:F1} MiB allocated): {error}");
@@ -254,6 +291,7 @@ internal sealed class AudioClipStore : IDisposable
 
     // ── Arrays ──
 
+    /// <summary>Takes a pooled array of <see cref="AudioClipSource.ChunkFloats"/> floats, or allocates (and counts) a new one. Contents are undefined.</summary>
     internal float[] RentChunkArray()
     {
         lock (_poolLock)
@@ -265,6 +303,7 @@ internal sealed class AudioClipStore : IDisposable
         return data;
     }
 
+    /// <summary>Puts a rented array back into the pool (it stays counted); after dispose it is dropped and uncounted.</summary>
     internal void ReturnChunkArray(float[] data)
     {
         if (_disposed)
@@ -278,6 +317,7 @@ internal sealed class AudioClipStore : IDisposable
         }
     }
 
+    /// <summary>Allocates a counted array of exactly <paramref name="floats"/> floats (resident chunks, copied Unity clip blocks).</summary>
     internal float[] AllocateExactArray(int floats)
     {
         var data = new float[floats];
@@ -285,8 +325,10 @@ internal sealed class AudioClipStore : IDisposable
         return data;
     }
 
+    /// <summary>Uncounts an array from <see cref="AllocateExactArray"/>; the array itself is left to the garbage collector.</summary>
     internal void FreeExactArray(float[] data) => AddAllocated(-data.LongLength * sizeof(float));
 
+    /// <summary>Adds <paramref name="bytes"/> (negative to subtract) to the allocation counter and raises the peak lock-free.</summary>
     private void AddAllocated(long bytes)
     {
         var current = Interlocked.Add(ref _allocatedBytes, bytes);
@@ -297,6 +339,7 @@ internal sealed class AudioClipStore : IDisposable
         }
     }
 
+    /// <summary>Logs the source count and the current and peak sample memory in MiB.</summary>
     public void LogMemoryUsage()
     {
         int sourceCount;

Util/Audio/Clip/DecodeStream.cs

@@ -18,18 +18,34 @@ internal sealed class DecodeStream : IDisposable
     /// <summary>Input frames read from the reader per resampler call.</summary>
     private const int ReadBlockFrames = 4096;
 
+    /// <summary>Resampler from the reader's rate to the output rate; null when the rates are equal (samples are copied).</summary>
     private readonly PCMResampler? _resampler;
+
     private readonly int _channels;
     private readonly int _outputRate;
+
+    /// <summary>Input block of <see cref="ReadBlockFrames"/> frames, interleaved.</summary>
     private readonly float[] _readBuffer;
+
+    /// <summary>Scratch output for frames discarded after a restart; allocated on first use.</summary>
     private float[]? _discardBuffer;
+
+    /// <summary>True once the reader returned no more input and the resampler is being drained with Flush.</summary>
     private bool _flushing;
+
+    /// <summary>True once the input and the resampler tail are exhausted; the stream must restart before producing more.</summary>
     private bool _ended;
 
+    /// <summary>Input frames per alignment step: input rate / gcd (1 without resampling).</summary>
     private readonly long _inputStep;
+
+    /// <summary>Output frames per alignment step: output rate / gcd (1 without resampling).</summary>
     private readonly long _outputStep;
+
+    /// <summary>Input frames fed before the requested position on a restart, so the filter history matches a continuous run.</summary>
     private readonly long _prerollInputFrames;
 
+    /// <summary>Reader of this stream (owned; disposed with the stream).</summary>
     public IPCMReader Reader { get; }
 
     /// <summary>Output frame the stream continues at, or -1 when the stream is not positioned.</summary>
@@ -41,6 +57,8 @@ internal sealed class DecodeStream : IDisposable
     /// <summary>Number of times the stream started anew (seek + resampler reset).</summary>
     public int RestartCount { get; private set; }
 
+    /// <param name="reader">Reader of the clip; ownership passes to the stream.</param>
+    /// <param name="outputRate">Output sample rate in Hz.</param>
     public DecodeStream(IPCMReader reader, int outputRate)
     {
         Reader = reader;
@@ -58,6 +76,7 @@ internal sealed class DecodeStream : IDisposable
             // History fed before the first kept output frame when a stream starts mid-clip.
             // The filter spans about filter_size input frames per output frame at ratios up to 1:1
             // and filter_size * (input rate / output rate) input frames when downsampling.
+            // The preroll is four times that span plus one alignment step (the restart position is rounded down to a step).
             var ratio = Math.Max(1L, (reader.SampleRate + outputRate - 1L) / outputRate);
             _prerollInputFrames = 4L * _resampler.FilterSize * ratio + _inputStep;
         }
@@ -77,6 +96,7 @@ internal sealed class DecodeStream : IDisposable
         var channels = _channels;
         var filled = 0;
 
+        // Same rate: output frame = input frame; seek only when the reader is not already at the start.
         if (_resampler == null)
         {
             if (Reader.Position != start)
@@ -115,6 +135,7 @@ internal sealed class DecodeStream : IDisposable
         fixed (float* pIn = _readBuffer)
         fixed (float* pOut = data)
         {
+            // Produce and drop the output frames between the aligned restart position and the requested start.
             while (discard > 0 && !_ended)
             {
                 _discardBuffer ??= new float[ReadBlockFrames * channels];
@@ -167,12 +188,14 @@ internal sealed class DecodeStream : IDisposable
         return 0;
     }
 
+    /// <summary>Releases the resampler and the reader.</summary>
     public void Dispose()
     {
         _resampler?.Dispose();
         Reader.Dispose();
     }
 
+    /// <summary>Greatest common divisor of two positive integers (Euclid).</summary>
     private static int GCD(int a, int b)
     {
         while (b != 0) (a, b) = (b, a % b);

Util/Audio/Clip/FFmpegPCMReader.cs

@@ -31,12 +31,20 @@ internal sealed unsafe class FFmpegPCMReader : IPCMReader
     /// </summary>
     private const double SeekMarginSeconds = 0.25;
 
+    // FFmpeg objects owned by this reader, freed by Dispose (null after).
     private AVFormatContext* _format;
     private AVCodecContext* _codec;
+
+    /// <summary>Sample format converter: decoder format to interleaved float, same rate and layout.</summary>
     private SwrContext* _swr;
+
     private AVPacket* _packet;
     private AVFrame* _frame;
+
+    /// <summary>Index of the decoded audio stream in the container; every other stream is discarded by the demuxer.</summary>
     private readonly int _streamIndex;
+
+    /// <summary>Time base of the stream's timestamps (seconds per tick).</summary>
     private readonly AVRational _timeBase;
     private readonly long _ptsOrigin;  // Stream timestamp of output frame _leadFrames
     private readonly long _leadFrames; // Silent frames placed before the first decoded frame (MP3 header frame, see class summary)
@@ -49,14 +57,27 @@ internal sealed unsafe class FFmpegPCMReader : IPCMReader
 
     private long _nextDecodedFrame; // Frame index of the next decoded frame when counting sequentially
     private bool _syncToTimestamp;  // True until the first frame after open/seek sets _nextDecodedFrame from its timestamp
+    // _flushSent: the null packet (drain request) was sent at the end of the file.
+    // _endOfStream: the decoder returned EOF, or nothing more after the drain request.
     private bool _flushSent;
     private bool _endOfStream;
 
+    /// <summary>File path the reader was opened with.</summary>
     public string Path { get; }
+
+    /// <inheritdoc/>
     public int Channels { get; }
+
+    /// <inheritdoc/>
     public int SampleRate { get; }
+
+    /// <inheritdoc/>
     public long TotalFrames { get; }
+
+    /// <summary>False: the reader seeks within the file.</summary>
     public bool IsForwardOnly => false;
+
+    /// <inheritdoc/>
     public long Position { get; private set; }
 
     /// <summary>True when the stream is MP3 and is decoded with the game's MP3 timing (see class summary).</summary>
@@ -65,6 +86,12 @@ internal sealed unsafe class FFmpegPCMReader : IPCMReader
     /// <summary>Number of demuxer seeks performed (for diagnostics).</summary>
     public int SeekCount { get; private set; }
 
+    /// <summary>
+    /// Opens <paramref name="path"/>, selects the best audio stream and opens its decoder. For MP3 files the whole file is
+    /// scanned once to count frames (see the class summary).
+    /// </summary>
+    /// <exception cref="InvalidOperationException">The file cannot be opened, has no decodable audio stream, has no duration
+    /// (non-MP3), or an FFmpeg setup call fails. Everything allocated so far is freed.</exception>
     public FFmpegPCMReader(string path)
     {
         Path = path;
@@ -181,6 +208,11 @@ internal sealed unsafe class FFmpegPCMReader : IPCMReader
             throw new InvalidOperationException($"Failed to rewind '{Path}': {ErrorString(seek)}");
     }
 
+    /// <summary>
+    /// Frame count from the stream duration, or from the container duration (AV_TIME_BASE units, microseconds) when the stream
+    /// has none.
+    /// </summary>
+    /// <exception cref="InvalidOperationException">Neither duration is known.</exception>
     private long EstimateTotalFrames(AVStream* stream)
     {
         if (stream->duration != ffmpeg.AV_NOPTS_VALUE && stream->duration > 0)
@@ -190,6 +222,13 @@ internal sealed unsafe class FFmpegPCMReader : IPCMReader
         throw new InvalidOperationException($"Audio file '{Path}' has no duration.");
     }
 
+    /// <summary>
+    /// Moves to <paramref name="frame"/> (0 ~ <see cref="TotalFrames"/>). A target within the pending block or up to the seek margin
+    /// after it is reached by decoding forward; otherwise the demuxer seeks backward (AVSEEK_FLAG_BACKWARD) to target - margin
+    /// (or to the stream start if that fails) and the decoder is flushed. Decoded samples before the target are discarded by Read.
+    /// </summary>
+    /// <exception cref="ArgumentOutOfRangeException"><paramref name="frame"/> is outside 0 ~ TotalFrames.</exception>
+    /// <exception cref="InvalidOperationException">The demuxer cannot seek.</exception>
     public void Seek(long frame)
     {
         if (frame < 0 || frame > TotalFrames) throw new ArgumentOutOfRangeException(nameof(frame));
@@ -205,6 +244,7 @@ internal sealed unsafe class FFmpegPCMReader : IPCMReader
             return;
         }
 
+        // Target timestamp in stream ticks; the lead (silent) frames have no packets, so they are subtracted first.
         var targetTs = _ptsOrigin + ffmpeg.av_rescale_q(Math.Max(0, frame - _leadFrames - marginFrames), new AVRational { num = 1, den = SampleRate }, _timeBase);
         var ret = ffmpeg.av_seek_frame(_format, _streamIndex, targetTs, ffmpeg.AVSEEK_FLAG_BACKWARD);
         if (ret < 0)
@@ -222,6 +262,12 @@ internal sealed unsafe class FFmpegPCMReader : IPCMReader
         Position = frame;
     }
 
+    /// <inheritdoc/>
+    /// <remarks>
+    /// Frames before the first decoded frame (MP3 lead silence) and gaps between decoded timestamps are returned as zeros.
+    /// Returns fewer frames than requested when decoding ends before <see cref="TotalFrames"/>.
+    /// </remarks>
+    /// <exception cref="InvalidOperationException">Reading, decoding or sample conversion fails.</exception>
     public int Read(float[] buffer, int frameCount)
     {
         var limit = (int)Math.Min(frameCount, TotalFrames - Position);
@@ -264,6 +310,10 @@ internal sealed unsafe class FFmpegPCMReader : IPCMReader
     }
 
     /// <summary>Decodes the next audio frame into the pending buffer. Returns false at the end of the stream.</summary>
+    /// <remarks>
+    /// Send/receive loop: receive a frame; on EAGAIN read and send the next packet of the stream; at the end of the file send a
+    /// null packet to drain the decoder, then receive until EOF.
+    /// </remarks>
     private bool DecodeNextFrame()
     {
         while (!_endOfStream)
@@ -315,6 +365,10 @@ internal sealed unsafe class FFmpegPCMReader : IPCMReader
         return false;
     }
 
+    /// <summary>
+    /// Converts the decoded frame to interleaved float into the pending buffer and assigns its frame position: from its timestamp
+    /// for the first frame after open/seek (the current position when it has none), sequential afterwards.
+    /// </summary>
     private void StoreFrame()
     {
         var samples = _frame->nb_samples;
@@ -347,6 +401,7 @@ internal sealed unsafe class FFmpegPCMReader : IPCMReader
         _nextDecodedFrame += samples;
     }
 
+    /// <summary>Frees every FFmpeg object and closes the file. Safe to call more than once and on a partly constructed reader.</summary>
     public void Dispose()
     {
         if (_frame != null)
@@ -381,6 +436,7 @@ internal sealed unsafe class FFmpegPCMReader : IPCMReader
         }
     }
 
+    /// <summary>FFmpeg error text for <paramref name="error"/> (av_strerror) followed by the numeric code.</summary>
     private static string ErrorString(int error)
     {
         var buffer = stackalloc byte[1024];

Util/Audio/Clip/MP3HeaderFrame.cs

@@ -37,8 +37,13 @@ internal static class MP3HeaderFrame
         return SilentFrames(file);
     }
 
+    /// <summary>
+    /// <see cref="SilentFrames(string)"/> for a seekable stream positioned anywhere (the stream is read from offset 0).
+    /// Only the first valid frame header within <see cref="SyncSearchBytes"/> after the ID3v2 tags is examined.
+    /// </summary>
     public static int SilentFrames(Stream stream)
     {
+        // Skip consecutive ID3v2 tags: 10-byte header + syncsafe size (+ 10-byte footer when flagged).
         var tag = new byte[10];
         long offset = 0;
         while (true)
@@ -65,6 +70,14 @@ internal static class MP3HeaderFrame
         return 0;
     }
 
+    /// <summary>
+    /// Parses the 4-byte frame header at <paramref name="i"/>. False for a missing sync or a reserved version, layer, bitrate
+    /// index (15) or sample rate index (3).
+    /// </summary>
+    /// <param name="data">Bytes to parse.</param>
+    /// <param name="i">Offset of the first header byte in <paramref name="data"/>.</param>
+    /// <param name="samplesPerFrame">Samples per channel in the frame (384, 576 or 1152).</param>
+    /// <param name="tagOffset">Offset of a Xing/Info tag from the header start: 4 + CRC (2) + Layer III side information (0 for Layers I/II).</param>
     private static bool TryParseHeader(byte[] data, int i, out int samplesPerFrame, out int tagOffset)
     {
         samplesPerFrame = 0;
@@ -91,6 +104,7 @@ internal static class MP3HeaderFrame
         return true;
     }
 
+    /// <summary>True when the ASCII string <paramref name="tag"/> is at <paramref name="at"/> within the first <paramref name="length"/> bytes.</summary>
     private static bool HasTag(byte[] data, int length, int at, string tag)
     {
         if (at < 0 || at + tag.Length > length) return false;
@@ -99,6 +113,7 @@ internal static class MP3HeaderFrame
         return true;
     }
 
+    /// <summary>Reads until <paramref name="count"/> bytes or the end of the stream; returns the bytes read.</summary>
     private static int ReadFully(Stream stream, byte[] buffer, int count)
     {
         var total = 0;

Util/Audio/Clip/MP3MonoLayoutReader.cs

@@ -16,6 +16,8 @@ namespace ADOFAIRenderer.Util.Audio.Clip;
 internal sealed class MP3MonoLayoutReader : IPCMReader
 {
     private readonly IPCMReader _inner;
+
+    /// <summary>Reused buffer for inner frames, grown to the largest request.</summary>
     private float[] _innerBuffer = Array.Empty<float>();
 
     /// <param name="inner">Mono reader of the MP3 file with the game's MP3 timing (<see cref="FFmpegPCMReader.IsMP3"/>). Owned by this reader.</param>
@@ -26,10 +28,19 @@ internal sealed class MP3MonoLayoutReader : IPCMReader
         Position = inner.Position * 2;
     }
 
+    /// <summary>Always 1.</summary>
     public int Channels => 1;
+
+    /// <summary>The inner reader's sample rate (the game plays the doubled data at this rate).</summary>
     public int SampleRate => _inner.SampleRate;
+
+    /// <summary>Twice the inner frame count.</summary>
     public long TotalFrames => _inner.TotalFrames * 2;
+
+    /// <inheritdoc/>
     public bool IsForwardOnly => _inner.IsForwardOnly;
+
+    /// <inheritdoc/>
     public long Position { get; private set; }
 
     /// <summary>Moves to <paramref name="frame"/>; the inner reader moves to the inner frame of the next even position.</summary>
@@ -39,12 +50,14 @@ internal sealed class MP3MonoLayoutReader : IPCMReader
         Position = frame;
     }
 
+    /// <inheritdoc/>
     public int Read(float[] buffer, int frameCount)
     {
         var limit = (int)Math.Min(frameCount, TotalFrames - Position);
         var written = 0;
         while (written < limit)
         {
+            // Odd position: the zero slot after an inner sample (also the first frame after a seek to an odd frame).
             if ((Position & 1) == 1)
             {
                 buffer[written++] = 0f;
@@ -52,6 +65,7 @@ internal sealed class MP3MonoLayoutReader : IPCMReader
                 continue;
             }
 
+            // Even position: read enough inner frames for the remaining output, then interleave each with a zero.
             var want = (limit - written + 1) / 2;
             if (_innerBuffer.Length < want) _innerBuffer = new float[want];
             var got = _inner.Read(_innerBuffer, want);
@@ -69,5 +83,6 @@ internal sealed class MP3MonoLayoutReader : IPCMReader
         return written;
     }
 
+    /// <summary>Disposes the inner reader.</summary>
     public void Dispose() => _inner.Dispose();
 }

Util/Audio/Clip/MemoryPCMReader.cs

@@ -11,19 +11,38 @@ namespace ADOFAIRenderer.Util.Audio.Clip;
 /// </summary>
 internal sealed class MemoryPCMReader : IPCMReader
 {
+    /// <summary>Block arrays; an entry is set to null when the block is released.</summary>
     private readonly float[]?[] _blocks;
+
+    /// <summary>Called with each released block (for example to uncount its memory in the store); may be null.</summary>
     private readonly Action<float[]>? _onBlockReleased;
+
     private int _releasedCount; // Blocks [0, _releasedCount) are released
 
+    /// <inheritdoc/>
     public int Channels { get; }
+
+    /// <inheritdoc/>
     public int SampleRate { get; }
+
+    /// <inheritdoc/>
     public long TotalFrames { get; }
+
+    /// <summary>True: blocks are released as they are read.</summary>
     public bool IsForwardOnly => true;
+
+    /// <inheritdoc/>
     public long Position { get; private set; }
 
     /// <summary>Frames per block (all blocks except the last).</summary>
     public int FramesPerBlock { get; }
 
+    /// <param name="blocks">Interleaved blocks in frame order; the reader takes ownership of the arrays (the list is copied).</param>
+    /// <param name="framesPerBlock">Frames in every block except possibly the last (positive).</param>
+    /// <param name="channels">Channel count (positive).</param>
+    /// <param name="sampleRate">Sample rate in Hz.</param>
+    /// <param name="totalFrames">Frame count; the blocks must hold at least this many frames.</param>
+    /// <param name="onBlockReleased">Called with each block when it is released; may be null.</param>
     public MemoryPCMReader(IReadOnlyList<float[]> blocks, int framesPerBlock, int channels, int sampleRate, long totalFrames,
         Action<float[]>? onBlockReleased)
     {
@@ -40,6 +59,8 @@ internal sealed class MemoryPCMReader : IPCMReader
         TotalFrames = totalFrames;
     }
 
+    /// <inheritdoc/>
+    /// <exception cref="InvalidOperationException"><paramref name="frame"/> lies in a block that was already released.</exception>
     public void Seek(long frame)
     {
         if (frame < 0 || frame > TotalFrames) throw new ArgumentOutOfRangeException(nameof(frame));
@@ -48,6 +69,8 @@ internal sealed class MemoryPCMReader : IPCMReader
         Position = frame;
     }
 
+    /// <inheritdoc/>
+    /// <remarks>Blocks whose end the position has passed are released after each copy.</remarks>
     public int Read(float[] buffer, int frameCount)
     {
         var total = (int)Math.Min(frameCount, TotalFrames - Position);
@@ -68,6 +91,7 @@ internal sealed class MemoryPCMReader : IPCMReader
         return written;
     }
 
+    /// <summary>Releases every block with an index below <paramref name="blockIndex"/> that is not released yet, in order.</summary>
     private void ReleaseBlocksBefore(int blockIndex)
     {
         while (_releasedCount < blockIndex && _releasedCount < _blocks.Length)
@@ -79,5 +103,6 @@ internal sealed class MemoryPCMReader : IPCMReader
         }
     }
 
+    /// <summary>Releases every remaining block. Safe to call more than once.</summary>
     public void Dispose() => ReleaseBlocksBefore(_blocks.Length);
 }

Util/Audio/Clip/PCMResampler.cs

@@ -11,16 +11,27 @@ namespace ADOFAIRenderer.Util.Audio.Clip;
 /// </summary>
 internal sealed unsafe class PCMResampler : IDisposable
 {
+    /// <summary>Resampler context owned by this instance; null after <see cref="Dispose"/>.</summary>
     private SwrContext* _swr;
+
+    /// <summary>True after <see cref="Flush"/> until <see cref="Reset"/>.</summary>
     private bool _flushed;
 
+    /// <summary>Channel count of input and output (interleaved).</summary>
     public int Channels { get; }
+
+    /// <summary>Input sample rate in Hz.</summary>
     public int InputRate { get; }
+
+    /// <summary>Output sample rate in Hz.</summary>
     public int OutputRate { get; }
 
     /// <summary>Value of the SwrContext "filter_size" option (filter length per phase in taps at a 1:1 ratio).</summary>
     public int FilterSize { get; }
 
+    /// <summary>Creates and initializes a float-to-float resampler with the default channel layout for <paramref name="channels"/>.</summary>
+    /// <exception cref="ArgumentOutOfRangeException">A count or rate is not positive.</exception>
+    /// <exception cref="InvalidOperationException">libswresample cannot allocate or initialize the context.</exception>
     public PCMResampler(int channels, int inputRate, int outputRate)
     {
         if (channels <= 0) throw new ArgumentOutOfRangeException(nameof(channels));
@@ -45,6 +56,8 @@ internal sealed unsafe class PCMResampler : IDisposable
             throw new InvalidOperationException($"swr_alloc_set_opts2 failed ({ret}).");
         _swr = swr;
 
+        // Falls back to 32, the libswresample default of "filter_size", when the option cannot be read.
+        // Reference: https://github.com/FFmpeg/FFmpeg/blob/master/libswresample/options.c (filter_size)
         long filterSize;
         FilterSize = ffmpeg.av_opt_get_int(_swr, "filter_size", 0, &filterSize) >= 0 ? (int)filterSize : 32;
 
@@ -96,6 +109,7 @@ internal sealed unsafe class PCMResampler : IDisposable
         return ret;
     }
 
+    /// <summary>Frees the context. Safe to call more than once.</summary>
     public void Dispose()
     {
         if (_swr == null) return;

Util/Audio/Clip/UnityClipLoader.cs

@@ -7,7 +7,7 @@ namespace ADOFAIRenderer.Util.Audio.Clip;
 /// <summary>
 /// Copies a Unity <see cref="AudioClip"/> into memory for clips without a file on disk
 /// (built-in hit sounds from Resources, official/DLC level audio).
-/// <see cref="AudioClip.GetData(float[], int)"/> runs on the main thread only, so the whole clip is copied once on the main thread
+/// <see cref="AudioClip.GetData(float[], int)"/> runs on the main Unity thread only, so the whole clip is copied once on the main Unity thread
 /// and the decoder thread reads the copy through a <see cref="MemoryPCMReader"/>.
 /// Streaming clips (<see cref="AudioClipLoadType.Streaming"/>) are rejected because GetData does not read them.
 /// Reference: https://docs.unity3d.com/ScriptReference/AudioClip.GetData.html
@@ -25,6 +25,9 @@ internal static class UnityClipLoader
         if (clip.loadType == AudioClipLoadType.Streaming)
             throw new NotSupportedException($"AudioClip '{clip.name}' is a streaming clip; GetData cannot read it.");
 
+        // Clips with preloadAudioData off start unloaded; LoadAudioData loads the data synchronously, or asynchronously for
+        // clips with loadInBackground (GetData below then fails while the data is still loading).
+        // Reference: https://docs.unity3d.com/ScriptReference/AudioClip.LoadAudioData.html
         if (clip.loadState == AudioDataLoadState.Unloaded)
             clip.LoadAudioData();
 

Util/Audio/Filter/Gain.cs

@@ -2,22 +2,31 @@ using System;
 
 namespace ADOFAIRenderer.Util.Audio.Filter;
 
+/// <summary>
+/// Constant gain: every sample is multiplied by 10^(<see cref="Level"/> / 20). Stateless and without latency.
+/// </summary>
 internal class Gain : IAudioFilter
 {
+    /// <summary>Gain in dB (0 = unchanged, -1 ≈ ×0.891, -6 ≈ ×0.501). Read on every sample, so changes apply immediately.</summary>
     public double Level = 0;
 
+    /// <inheritdoc/>
     public void Initialize(int sampleRate, int channels) { }
 
+    /// <summary>Returns <paramref name="sample"/> × 10^(<see cref="Level"/> / 20); <paramref name="channel"/> is not used.</summary>
     public double ProcessSample(double sample, int channel) =>
         sample * Math.Pow(10, Level / 20);
 
+    /// <inheritdoc/>
     public void ProcessBlock(Span<double> buffer)
     {
         for (var i = 0; i < buffer.Length; i++)
             buffer[i] = ProcessSample(buffer[i], 0); 
     }
 
+    /// <inheritdoc/>
     public void Reset() { }
 
+    /// <inheritdoc/>
     public double Latency => 0.0;
 }

Util/Audio/Filter/HardClip.cs

@@ -3,15 +3,22 @@ using System.Runtime.CompilerServices;
 
 namespace ADOFAIRenderer.Util.Audio.Filter;
 
+/// <summary>
+/// Hard clipper: limits every sample to [-<see cref="Threshold"/>, +<see cref="Threshold"/>]. Stateless and without latency.
+/// In the chain of <see cref="OfflineAudioMixer"/> it catches the peaks the RMS-based limiter lets through before the final gain.
+/// </summary>
 internal class HardClip : IAudioFilter
 {
+    /// <summary>Clip level as a linear amplitude (1.0 = full scale).</summary>
     // ReSharper disable once MemberCanBePrivate.Global
     // ReSharper disable once FieldCanBeMadeReadOnly.Global
     // ReSharper disable once ConvertToConstant.Global
     public double Threshold = 1.0;
         
+    /// <inheritdoc/>
     public void Initialize(int sampleRate, int channels) { }
         
+    /// <summary>Returns <paramref name="sample"/> clamped to ±<see cref="Threshold"/>; <paramref name="channel"/> is not used.</summary>
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
     public double ProcessSample(double sample, int channel)
     {
@@ -20,13 +27,16 @@ internal class HardClip : IAudioFilter
         return sample;
     }
 
+    /// <inheritdoc/>
     public void ProcessBlock(Span<double> buffer)
     {
         for (var i = 0; i < buffer.Length; i++)
             buffer[i] = ProcessSample(buffer[i], 0); 
     }
 
+    /// <inheritdoc/>
     public void Reset() { }
 
+    /// <inheritdoc/>
     public double Latency => 0.0;
 }

Util/Audio/Filter/IAudioFilter.cs

@@ -2,14 +2,34 @@ using System;
 
 namespace ADOFAIRenderer.Util.Audio.Filter;
 
+/// <summary>
+/// Stage of the output filter chain of <see cref="OfflineAudioMixer"/>. Samples are doubles at nominal full scale ±1.0.
+/// A filter keeps its own state between calls, so consecutive blocks form one continuous signal.
+/// Used by one thread at a time (the render thread during rendering).
+/// </summary>
 internal interface IAudioFilter
 {
+    /// <summary>
+    /// Sets the sample rate (Hz) and interleaved channel count of the signal and allocates per-channel state.
+    /// Called once before the first sample; the state is cleared as by <see cref="Reset"/>.
+    /// </summary>
     void Initialize(int sampleRate, int channels);
         
+    /// <summary>Processes one sample of channel <paramref name="channel"/> (0 ~ channels - 1) and returns the output sample.</summary>
     double ProcessSample(double sample, int channel);
+
+    /// <summary>
+    /// Processes <paramref name="buffer"/> in place. The buffer holds interleaved frames starting at channel 0
+    /// (length = frames * channels of <see cref="Initialize"/>).
+    /// </summary>
     void ProcessBlock(Span<double> buffer);
         
+    /// <summary>Clears the internal state (envelopes, delay lines) without changing the settings.</summary>
     void Reset();
 
+    /// <summary>
+    /// Delay of the output relative to the input, in seconds (0 for filters without look-ahead).
+    /// <see cref="OfflineAudioMixer"/> sums the latencies of the chain and compensates them.
+    /// </summary>
     double Latency { get; }
 }

Util/Audio/Filter/RMSCompressor.cs

@@ -3,6 +3,24 @@ using System.Runtime.CompilerServices;
 
 namespace ADOFAIRenderer.Util.Audio.Filter;
 
+/// <summary>
+/// Feed-forward RMS compressor with soft knee, attack/release ballistics in the dB domain and optional look-ahead.
+/// Each channel is detected and gain-reduced independently (no stereo link).
+///
+/// Per sample of channel c:
+/// 1. Mean square: ms[n] = r * ms[n-1] + (1 - r) * x[n]², r = exp(-1 / (sampleRate * <see cref="RmsWindowTime"/>));
+///    level L = 10 * log10(ms + 1e-12) dB (the 1e-12 floor keeps silence finite, about -120 dB).
+/// 2. Static curve (gain reduction G ≤ 0 dB, T = <see cref="ThresholdDb"/>, R = <see cref="Ratio"/>, W = <see cref="KneeDb"/>):
+///    G = (1/R - 1) * (L - T) above T + W/2; G = (1/R - 1) * (L - T + W/2)² / (2W) inside the knee; 0 below T - W/2.
+///    With W = 0 the knee is hard (G = (1/R - 1) * (L - T) above T). R = infinity gives G = T - L (a limiter at T).
+/// 3. Ballistics: g[n] = k * g[n-1] + (1 - k) * G, with k = attack coefficient while the reduction grows (G &lt; g[n-1]) and
+///    release coefficient otherwise; coefficient = exp(-1 / (sampleRate * time)) (one-pole smoothing, time constant in seconds).
+/// 4. Output = x[n - lookAhead] * 10^(g[n] / 20): the gain computed from the current input is applied to the input delayed by
+///    <see cref="LookAheadTime"/>, so the reduction starts before the peak reaches the output.
+///
+/// Properties may be set before <see cref="Initialize"/> (as in an object initializer); Initialize recomputes every
+/// coefficient for the actual sample rate and reallocates the delay lines. Not thread-safe.
+/// </summary>
 // ReSharper disable once InconsistentNaming
 internal class RMSCompressor : IAudioFilter
 {
@@ -13,11 +31,17 @@ internal class RMSCompressor : IAudioFilter
     private double _kneeDb = 5; // in dB
     private double _rmsWindowTime = 0.030; // in seconds
     private double _lookAheadTime; // in seconds
+
+    /// <summary>Look-ahead delay in samples per channel: round(sampleRate * <see cref="LookAheadTime"/>); 0 disables the delay line.</summary>
     private int _lookAheadSamples;
 
+    /// <summary>Sample rate in Hz; 44100 until <see cref="Initialize"/> sets the actual rate.</summary>
     private int _sampleRate = 44100;
+
+    /// <summary>Interleaved channel count; 2 until <see cref="Initialize"/> sets the actual count.</summary>
     private int _channels = 2;
 
+    // One-pole smoothing coefficients (0 ~ 1) of attack, release and the mean-square detector: exp(-1 / (sampleRate * time)).
     private double _attackCoef;
     private double _releaseCoef;
     private double _rmsCoef;
@@ -28,6 +52,10 @@ internal class RMSCompressor : IAudioFilter
     private double[][] _delayBuffers = Array.Empty<double[]>(); // circular delay buffers
     private int[] _delayWriteIndices = Array.Empty<int>();
 
+    /// <summary>
+    /// Look-ahead delay in seconds, clamped to 0 ~ 1. Setting it reallocates (and clears) the delay lines.
+    /// Also reported as <see cref="Latency"/>.
+    /// </summary>
     public double LookAheadTime
     {
         get => _lookAheadTime;
@@ -38,20 +66,24 @@ internal class RMSCompressor : IAudioFilter
         }
     }
 
+    /// <summary>Output delay in seconds: <see cref="LookAheadTime"/>.</summary>
     public double Latency => _lookAheadTime;
 
+    /// <summary>Threshold in dB relative to full scale (RMS level of a constant ±1.0 signal = 0 dB).</summary>
     public double ThresholdDb
     {
         get => _thresholdDb;
         set => _thresholdDb = value;
     }
 
+    /// <summary>Compression ratio (input dB above threshold : output dB above threshold), at least 1. Infinity limits at the threshold.</summary>
     public double Ratio
     {
         get => _ratio;
         set => _ratio = Math.Max(1, value);
     }
 
+    /// <summary>Attack time constant in seconds, at least 0.0001 (smaller values, including 0, are raised to it).</summary>
     public double AttackTime
     {
         get => _attackTime;
@@ -62,6 +94,7 @@ internal class RMSCompressor : IAudioFilter
         }
     }
 
+    /// <summary>Release time constant in seconds, at least 0.0001.</summary>
     public double ReleaseTime
     {
         get => _releaseTime;
@@ -72,12 +105,14 @@ internal class RMSCompressor : IAudioFilter
         }
     }
 
+    /// <summary>Total knee width in dB, centered on the threshold, at least 0 (0 = hard knee).</summary>
     public double KneeDb
     {
         get => _kneeDb;
         set => _kneeDb = Math.Max(0, value);
     }
 
+    /// <summary>Time constant of the mean-square detector in seconds, at least 0.0001.</summary>
     public double RmsWindowTime
     {
         get => _rmsWindowTime;
@@ -88,6 +123,7 @@ internal class RMSCompressor : IAudioFilter
         }
     }
 
+    /// <inheritdoc/>
     public void Initialize(int sampleRate, int channels)
     {
         _sampleRate = sampleRate;
@@ -110,6 +146,7 @@ internal class RMSCompressor : IAudioFilter
         ReallocateDelayBuffers();
     }
 
+    /// <summary>Allocates one zeroed circular buffer of <see cref="_lookAheadSamples"/> samples per channel.</summary>
     private void ReallocateDelayBuffers()
     {
         if (_channels <= 0) return;
@@ -139,6 +176,10 @@ internal class RMSCompressor : IAudioFilter
         _rmsCoef = Math.Exp(-1.0 / (_sampleRate * _rmsWindowTime));
     }
 
+    /// <summary>
+    /// Processes one sample of <paramref name="channel"/> (see the class summary). A channel outside 0 ~ channels - 1 is
+    /// returned unchanged and does not touch any state.
+    /// </summary>
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
     public double ProcessSample(double sample, int channel)
     {
@@ -162,10 +203,12 @@ internal class RMSCompressor : IAudioFilter
         {
             if (rmsDb > _thresholdDb + _kneeDb * 0.5)
             {
+                // Above the knee: full ratio.
                 gStatic = (1 / _ratio - 1) * (rmsDb - _thresholdDb);
             }
             else if (rmsDb >= _thresholdDb - _kneeDb * 0.5)
             {
+                // Inside the knee: quadratic transition from 0 dB at T - W/2 to the full-ratio line at T + W/2.
                 double diff = rmsDb - _thresholdDb + _kneeDb * 0.5;
                 gStatic = (1 / _ratio - 1) * diff * diff / (2 * _kneeDb);
             }
@@ -194,6 +237,7 @@ internal class RMSCompressor : IAudioFilter
 
         if (_lookAheadSamples > 0 && _delayBuffers.Length > channel && _delayBuffers[channel].Length > 0)
         {
+            // Circular delay line: read the sample written _lookAheadSamples calls ago, then overwrite it with the current one.
             var buffer = _delayBuffers[channel];
             int writeIdx = _delayWriteIndices[channel];
             double delayedSample = buffer[writeIdx];
@@ -205,6 +249,7 @@ internal class RMSCompressor : IAudioFilter
         return sample * linearGain;
     }
 
+    /// <inheritdoc/>
     public void ProcessBlock(Span<double> buffer)
     {
         for (var i = 0; i < buffer.Length; i++)
@@ -214,6 +259,7 @@ internal class RMSCompressor : IAudioFilter
         }
     }
 
+    /// <summary>Clears the detector, the gain envelope and the delay lines (the delay outputs zeros for the next look-ahead samples).</summary>
     public void Reset()
     {
         Array.Clear(_rmsState, 0, _rmsState.Length);

Util/Audio/Mixer/Voice.cs

@@ -6,11 +6,11 @@ using ADOFAIRenderer.Util.Audio.Clip;
 namespace ADOFAIRenderer.Util.Audio.Mixer;
 
 /// <summary>
-/// One playing sound of a <see cref="VoiceMixer"/> (the song, or one effect sound), created by <see cref="VoiceMixer.Play"/>.
+/// One playing sound of a <see cref="VoiceMixer"/> (the song, or one sound effect), created by <see cref="VoiceMixer.Play"/>.
 ///
 /// Main thread: the Set methods queue a change that takes effect at a given time (seconds relative to the render start,
 /// the time at which the game made the change). Changes of one voice must be queued in non-decreasing time order.
-/// Render thread: <see cref="VoiceMixer.Mix"/> applies each change at sample round(time * OutputRate).
+/// Render thread: <see cref="VoiceMixer.Mix"/> applies each change at sample floor(time * OutputRate) (<see cref="VoiceMixer.ToSample"/>).
 ///
 /// Playback model (output samples n, clip positions in frames of the source at the output sample rate):
 /// - The voice is silent before its start sample and from its end sample on.
@@ -21,20 +21,37 @@ namespace ADOFAIRenderer.Util.Audio.Mixer;
 /// </summary>
 internal sealed class Voice
 {
+    /// <summary>Kind of a queued <see cref="Change"/>; the meaning of <see cref="Change.Value"/> depends on it.</summary>
     internal enum ChangeKind
     {
+        /// <summary>Value: playback rate, at least 0.</summary>
         Pitch,
+
+        /// <summary>Value: linear gain.</summary>
         Volume,
+
+        /// <summary>Value: 1 = loop on, 0 = loop off.</summary>
         Loop,
+
+        /// <summary>Value: clip position in seconds, at least 0.</summary>
         Position,
+
+        /// <summary>Value: end time in seconds relative to the render start.</summary>
         EndTime,
+
+        /// <summary>Value: unused (0). Ends playback at the sample the change is applied at.</summary>
         Stop
     }
 
+    /// <summary>One timed change of a voice, queued by the main Unity thread and applied by the render thread.</summary>
     internal readonly struct Change
     {
         public readonly ChangeKind Kind;
+
+        /// <summary>Output sample at which the change takes effect (<see cref="VoiceMixer.ToSample"/> of the change time).</summary>
         public readonly long Sample;
+
+        /// <summary>Argument of the change (see <see cref="ChangeKind"/>).</summary>
         public readonly double Value;
 
         public Change(ChangeKind kind, long sample, double value)
@@ -45,6 +62,7 @@ internal sealed class Voice
         }
     }
 
+    /// <summary>Mixer that owns this voice; the Set methods queue their changes on it.</summary>
     private readonly VoiceMixer _mixer;
 
     // ── Render thread state ──
@@ -58,11 +76,22 @@ internal sealed class Voice
     /// <summary>Output sample at which playback stops (exclusive); long.MaxValue when not set.</summary>
     internal long EndSample = long.MaxValue;
 
+    /// <summary>Output sample of the current anchor (see the class summary).</summary>
     internal long AnchorSample;
+
+    /// <summary>Clip position at <see cref="AnchorSample"/>, in frames at the output sample rate (may be fractional).</summary>
     internal double AnchorPosition;
+
+    /// <summary>Clip frames advanced per output sample (1 = original speed), at least 0.</summary>
     internal double Pitch;
+
+    /// <summary>Linear gain applied to the clip samples.</summary>
     internal double Volume;
+
+    /// <summary>True while the clip repeats at <see cref="Period"/>.</summary>
     internal bool Loop;
+
+    /// <summary>Set by the render thread when playback has ended; the voice is then released and removed from the mixer.</summary>
     internal bool Finished;
 
     /// <summary>
@@ -74,7 +103,10 @@ internal sealed class Voice
     /// <summary>Loop length in frames at the output sample rate (source duration * output rate).</summary>
     internal double Period;
 
+    /// <summary>Read position registered on <see cref="Source"/> so the decoder thread keeps the chunks ahead loaded; null without a usable source.</summary>
     internal AudioCursor? Cursor;
+
+    /// <summary>Chunk of <see cref="Source"/> currently held for reading (invalid when none). Render thread only.</summary>
     internal ChunkView View;
 
     internal Voice(VoiceMixer mixer, AudioClipSource? source, string name)
@@ -128,6 +160,9 @@ internal sealed class Voice
     /// </summary>
     internal void Apply(in Change change, long sample, int outputRate)
     {
+        // Anchor changes made before the start take effect at the start sample (playback starts from the new state).
+        // EndTime uses the change's own value; Stop ends at the sample it is applied at, so a Stop before the start
+        // ends the voice before it plays.
         var at = Math.Max(sample, StartSample);
         switch (change.Kind)
         {
@@ -155,6 +190,7 @@ internal sealed class Voice
         }
     }
 
+    /// <summary>Moves the anchor to <paramref name="sample"/>, keeping the (wrapped) position there, before a pitch or loop change.</summary>
     private void Reanchor(long sample)
     {
         AnchorPosition = WrappedPositionAt(sample);

Util/Audio/Mixer/VoiceMixer.cs

@@ -9,7 +9,7 @@ namespace ADOFAIRenderer.Util.Audio.Mixer;
 /// Mixes every <see cref="Voice"/> into interleaved double samples at the output sample rate and channel count.
 ///
 /// Time: output sample n is at n / OutputRate seconds relative to the render start (the same time base as the times passed
-/// to <see cref="Play"/> and the Voice Set methods). A time t maps to sample round(t * OutputRate).
+/// to <see cref="Play"/> and the Voice Set methods). A time t maps to sample floor(t * OutputRate) (<see cref="ToSample"/>).
 ///
 /// Threads:
 /// - Main thread: <see cref="Play"/> and the Voice Set methods queue commands under a lock. Commands must be queued in
@@ -25,16 +25,23 @@ namespace ADOFAIRenderer.Util.Audio.Mixer;
 /// </summary>
 internal sealed class VoiceMixer : IDisposable
 {
+    /// <summary>Kind of a queued main-thread command.</summary>
     private enum CommandKind
     {
+        /// <summary>Adds a new voice to the mixed set (created by <see cref="VoiceMixer.Play"/>).</summary>
         Play,
+
+        /// <summary>Appends a <see cref="Voice.Change"/> to the voice's pending queue.</summary>
         Change
     }
 
+    /// <summary>Command queued by the main Unity thread and taken by the render thread at the start of <see cref="Mix"/>.</summary>
     private readonly struct Command
     {
         public readonly CommandKind Kind;
         public readonly Voice Voice;
+
+        /// <summary>The change for <see cref="CommandKind.Change"/>; default for <see cref="CommandKind.Play"/>.</summary>
         public readonly Voice.Change Change;
 
         public Command(CommandKind kind, Voice voice, Voice.Change change)
@@ -48,6 +55,8 @@ internal sealed class VoiceMixer : IDisposable
     private readonly AudioClipStore _store;
     private readonly CancellationToken _cancellationToken;
 
+    // Double-buffered command lists: the main Unity thread appends to _commands under _commandLock; the render thread swaps the
+    // two lists under the lock and processes _takenCommands outside it, then clears it for the next swap.
     private readonly object _commandLock = new();
     private List<Command> _commands = new();
     private List<Command> _takenCommands = new();
@@ -68,8 +77,10 @@ internal sealed class VoiceMixer : IDisposable
         _cancellationToken = cancellationToken;
     }
 
+    /// <summary>Output sample rate in Hz (the store's <see cref="AudioClipStore.OutputRate"/>).</summary>
     public int OutputRate { get; }
 
+    /// <summary>Interleaved channel count of the mixed output (1 or more).</summary>
     public int OutputChannels { get; }
 
     /// <summary>Voices currently mixed (started or waiting to start). Render thread only.</summary>
@@ -113,6 +124,10 @@ internal sealed class VoiceMixer : IDisposable
         return voice;
     }
 
+    /// <summary>
+    /// Queues a change of <paramref name="voice"/> that takes effect at sample <see cref="ToSample"/>(<paramref name="time"/>).
+    /// Called by the Voice Set methods on the main Unity thread.
+    /// </summary>
     internal void Enqueue(Voice voice, Voice.ChangeKind kind, double time, double value)
     {
         var change = new Voice.Change(kind, ToSample(time, OutputRate), value);
@@ -138,10 +153,13 @@ internal sealed class VoiceMixer : IDisposable
 
         TakeCommands();
 
+        // Iterated backwards so finished voices can be removed in place.
         for (var i = _voices.Count - 1; i >= 0; i--)
         {
             var voice = _voices[i];
             var sample = firstSample;
+            // Split the block into segments at the samples of pending changes: each segment is mixed with constant
+            // voice state, and a change is applied when the segment reaches its sample (or at once when its sample is past).
             while (!voice.Finished)
             {
                 var segmentEnd = endSample;
@@ -162,6 +180,8 @@ internal sealed class VoiceMixer : IDisposable
                 if (sample >= endSample) break;
             }
 
+            // The end sample is inside or before this block: nothing more will be mixed. Changes still pending for this voice
+            // (after the end) are dropped with it.
             if (!voice.Finished && endSample >= voice.EndSample)
                 voice.Finished = true;
             if (voice.Finished)
@@ -172,6 +192,10 @@ internal sealed class VoiceMixer : IDisposable
         }
     }
 
+    /// <summary>
+    /// Takes every queued command: Play adds the voice (with a cursor at frame 0 when its source is usable), Change appends to
+    /// the voice's pending queue (dropped for finished voices). Render thread only.
+    /// </summary>
     private void TakeCommands()
     {
         lock (_commandLock)
@@ -203,6 +227,7 @@ internal sealed class VoiceMixer : IDisposable
         var end = Math.Min(to, voice.EndSample);
         if (start >= end) return;
 
+        // A voice whose source is missing or failed is silent; it finishes at its first segment inside [start, end).
         var source = voice.Source;
         if (source == null || source.IsFailed)
         {
@@ -222,6 +247,7 @@ internal sealed class VoiceMixer : IDisposable
         var volume = voice.Volume;
         var offset = (int)(start - from) * channels;
 
+        // Move the cursor to the segment start so the decoder thread keeps the chunks ahead of it loaded.
         UpdateCursor(voice, (long)voice.WrappedPositionAt(start));
 
         for (var n = start; n < end; n++, offset += channels)
@@ -234,6 +260,8 @@ internal sealed class VoiceMixer : IDisposable
                     voice.Finished = true;
                     return;
                 }
+                // Looping: a wrapped position is below Period, and Period (Duration * rate) is at most TotalFrames
+                // (TotalFrames rounds up), so this is a guard that reads the last frame.
                 position = totalFrames - 1;
             }
 
@@ -243,6 +271,7 @@ internal sealed class VoiceMixer : IDisposable
             if (!EnsureView(voice, index)) return;
             var view = voice.View;
 
+            // Integer position (pitch 1 with an integer anchor): copy the stored sample.
             if (fraction == 0.0)
             {
                 for (var c = 0; c < channels; c++)
@@ -250,6 +279,7 @@ internal sealed class VoiceMixer : IDisposable
                 continue;
             }
 
+            // Linear interpolation; the next frame may lie in the following chunk, at the loop start or past the end.
             var nextIndex = index + 1;
             var nextInView = view.Contains(nextIndex);
             for (var c = 0; c < channels; c++)
@@ -303,6 +333,7 @@ internal sealed class VoiceMixer : IDisposable
         return false;
     }
 
+    /// <summary>Moves the voice's cursor to <paramref name="frame"/> and copies the voice's loop flag (writes only on change).</summary>
     private static void UpdateCursor(Voice voice, long frame)
     {
         var cursor = voice.Cursor;
@@ -311,6 +342,7 @@ internal sealed class VoiceMixer : IDisposable
         if (cursor.Position != frame) cursor.Position = frame;
     }
 
+    /// <summary>Releases the voice's held chunk and cursor and drops its pending changes. Render thread only.</summary>
     private static void ReleaseVoice(Voice voice)
     {
         var source = voice.Source;

Util/Audio/OfflineAudioMixer.cs

@@ -11,7 +11,7 @@ using UnityEngine;
 namespace ADOFAIRenderer.Util.Audio;
 
 /// <summary>
-/// Audio of one render: the song and effect sounds as <see cref="Voice"/>s of a <see cref="VoiceMixer"/>, clips from an
+/// Audio of one render: the song and sound effects as <see cref="Voice"/>s of a <see cref="VoiceMixer"/>, clips from an
 /// <see cref="AudioClipStore"/>, followed by the filter chain (RMS compressor → look-ahead limiter → hard clip → -1 dB gain).
 ///
 /// Time: seconds relative to the render start (RenderManager.dspTimeBase); output sample n is at n / sample rate.
@@ -21,15 +21,15 @@ namespace ADOFAIRenderer.Util.Audio;
 /// Threads:
 /// - Main thread: <see cref="InitializeBGM"/>, <see cref="CacheClip"/>, <see cref="RegisterSoundEvent"/>, <see cref="UpdateBGM"/>,
 ///   source/voice mapping, and <see cref="Commit"/> after each frame (all commands with an earlier time have been queued).
-/// - Render thread: <see cref="GenerateAudioForFrame"/> waits until the main thread has committed the end of the samples it mixes,
-///   so every command takes effect at its own sample. <see cref="Complete"/> ends the waiting when the main thread stops.
+/// - Render thread: <see cref="GenerateAudioForFrame"/> waits until the main Unity thread has committed the end of the samples it mixes,
+///   so every command takes effect at its own sample. <see cref="Complete"/> ends the waiting when the main Unity thread stops.
 /// </summary>
 internal sealed class OfflineAudioMixer : IDisposable
 {
-    /// <summary>Gain applied to every clip.</summary>
+    /// <summary>Linear gain applied to every clip (song and effects), before the filter chain (0.5 ≈ -6 dB headroom).</summary>
     private const double ClipVolume = 0.5;
 
-    /// <summary>Additional gain of effect sounds (registered with <see cref="RegisterSoundEvent"/>).</summary>
+    /// <summary>Additional gain of sound effects (registered with <see cref="RegisterSoundEvent"/>).</summary>
     private const double EffectVolume = 2.0 / 3.0;
 
     /// <summary>
@@ -41,21 +41,48 @@ internal sealed class OfflineAudioMixer : IDisposable
     /// <summary>Longest wait for a commit before checking for cancellation again, in milliseconds.</summary>
     private const int CommitWaitMs = 50;
 
+    /// <summary>Output channel count (interleaved).</summary>
     private readonly int _channels;
+
+    /// <summary>Output sample rate in Hz.</summary>
     private readonly int _sampleRate;
+
     private readonly AudioClipStore _store;
     private readonly VoiceMixer _mixer;
+
+    /// <summary>Canceled by <see cref="Cancel"/>/<see cref="Dispose"/>; ends commit waits and chunk waits on the render thread.</summary>
     private readonly CancellationTokenSource _cancellation = new();
+
+    /// <summary>Filter chain applied in list order to every mixed block.</summary>
     private readonly List<IAudioFilter> _filters = new();
+
+    /// <summary>Sum of the filter latencies in output samples: round(sum of <see cref="IAudioFilter.Latency"/> * sample rate).</summary>
     private readonly int _latencySamples;
 
     // Main thread.
+
+    /// <summary>
+    /// Mapping of game AudioSources to the state of the sound effect last started on them. Weak keys: a destroyed source
+    /// does not keep its state alive. Replaced by a new table to drop every mapping at once.
+    /// </summary>
     private ConditionalWeakTable<AudioSource, SourceState> _sourceStates = new();
+
+    /// <summary>Effect voices started since the last <see cref="StopAllEffects"/> (finished ones are pruned periodically).</summary>
     private readonly List<Voice> _effectVoices = new();
+
+    /// <summary>Count of <see cref="_effectVoices"/> at which the next prune runs.</summary>
     private int _effectVoicePruneAt = EffectVoicePruneCount;
+
+    /// <summary>Song source, or null when there is no song or it could not be loaded.</summary>
     private AudioClipSource? _bgmSource;
+
+    /// <summary>audioLib key (AudioClip.name) of the song.</summary>
     private string _bgmKey = "";
+
+    /// <summary>Current song voice, created by the first <see cref="UpdateBGM"/> and replaced when the start time changes.</summary>
     private Voice? _bgmVoice;
+
+    // Values last sent to the song voice (start in seconds relative to the render start); NaN before the first update.
     private double _bgmStart = double.NaN;
     private double _bgmPitch = double.NaN;
     private double _bgmVolume = double.NaN;
@@ -66,11 +93,26 @@ internal sealed class OfflineAudioMixer : IDisposable
 
     // Render thread (and Dispose, under _renderLock).
     private readonly object _renderLock = new();
+
+    /// <summary>Index of the next output sample <see cref="GenerateAudioForFrame"/> writes (frames per channel since the render start).</summary>
     private long _nextOutputSample;
+
+    /// <summary>True once the filters have been fed samples [0, latency).</summary>
     private bool _primed;
+
+    /// <summary>Reused interleaved mix buffer, grown to the largest block requested.</summary>
     private double[] _mixBuffer = Array.Empty<double>();
+
     private bool _disposed;
 
+    /// <summary>
+    /// Creates the clip store (and starts its decoder thread), the voice mixer and the filter chain.
+    /// Filter settings: RMS compressor (threshold -10 dB, ratio 2, attack/release 0.1 s, knee 10 dB, RMS window 0.02 s),
+    /// limiter (RMS compressor with threshold 0 dB, infinite ratio, attack 0 raised to the 0.0001 s minimum, release 0.05 s,
+    /// hard knee, RMS window 0.02 s, look-ahead 0.01 s), hard clip at ±1.0, then -1 dB gain.
+    /// </summary>
+    /// <param name="targetChannels">Output channel count (interleaved).</param>
+    /// <param name="targetSampleRate">Output sample rate in Hz; every clip is resampled to it.</param>
     public OfflineAudioMixer(int targetChannels, int targetSampleRate)
     {
         _channels = targetChannels;
@@ -96,6 +138,7 @@ internal sealed class OfflineAudioMixer : IDisposable
         _filters.Add(new HardClip());
         _filters.Add(new Gain { Level = -1 });
 
+        // Total delay of the chain; only the limiter's look-ahead contributes (0.01 s).
         double latency = 0;
         foreach (var filter in _filters)
         {
@@ -148,6 +191,8 @@ internal sealed class OfflineAudioMixer : IDisposable
         double pitch = conductor.song.pitch;
         var countdown = conductor.separateCountdownTime ? conductor.crotchetAtStart / pitch * conductor.adjustedCountdownTicks : 0.0;
         var start = conductor.dspTimeSong + countdown - dspTimeBase;
+        // levelData.volume is a percentage (100 = unchanged; scrConductor sets song.volume = volume * 0.01 the same way).
+        // Without a scnGame instance the level volume is 1.0.
         var levelVolume = scnGame.instance ? scnGame.instance.levelData.volume * 0.01 : 1.0;
         var volume = levelVolume * ClipVolume;
 
@@ -181,6 +226,11 @@ internal sealed class OfflineAudioMixer : IDisposable
         GetOrAddSource(clipName);
     }
 
+    /// <summary>
+    /// Source of the game clip <paramref name="clipName"/> (audioLib key): an existing source, or one opened through
+    /// <see cref="AudioClipResolver"/> with the clip from AudioManager.FindOrLoadAudioClip. Null for an empty name or an
+    /// unreadable clip (the key is then remembered as missing by the store). Main thread only.
+    /// </summary>
     private AudioClipSource? GetOrAddSource(string clipName)
     {
         if (string.IsNullOrEmpty(clipName)) return null;
@@ -190,9 +240,17 @@ internal sealed class OfflineAudioMixer : IDisposable
     }
 
     /// <summary>
-    /// Starts an effect sound at <paramref name="startTime"/>. An <paramref name="endTime"/> of 0 or more makes it loop until then.
+    /// Starts a sound effect at <paramref name="startTime"/>. An <paramref name="endTime"/> of 0 or more makes it loop until then.
     /// <paramref name="source"/> (when given) is mapped to the returned state, which reports and applies later changes through the AudioSource.
     /// </summary>
+    /// <param name="source">Game AudioSource playing the sound, or null to map it later with <see cref="MapSource"/>.</param>
+    /// <param name="clipName">audioLib key of the clip. A clip that cannot be loaded gives a silent voice.</param>
+    /// <param name="startTime">Scheduled start, seconds relative to the render start (a start before <paramref name="now"/> starts at now).</param>
+    /// <param name="endTime">Loop end, seconds relative to the render start; negative for a sound that plays once.</param>
+    /// <param name="volume">Game volume (linear); multiplied by the clip and effect gains.</param>
+    /// <param name="pitch">Playback rate at the start.</param>
+    /// <param name="now">Current render time in seconds.</param>
+    /// <returns>State of the new sound, also used by the AudioSource patches.</returns>
     public SourceState RegisterSoundEvent(AudioSource? source, string clipName, double startTime, double endTime, float volume, float pitch, double now)
     {
         var clipSource = GetOrAddSource(clipName);
@@ -200,6 +258,7 @@ internal sealed class OfflineAudioMixer : IDisposable
         var voice = _mixer.Play(clipSource, clipName, startTime, volume * ClipVolume * EffectVolume, pitch, loop, now);
         if (loop) voice.SetEndTime(endTime, now);
 
+        // Amortized pruning: the list is scanned only when it has doubled since the last prune.
         if (_effectVoices.Count >= _effectVoicePruneAt)
         {
             _effectVoices.RemoveAll(v => v.IsFinished);
@@ -224,7 +283,7 @@ internal sealed class OfflineAudioMixer : IDisposable
         _sourceStates.Add(source, state);
     }
 
-    /// <summary>State of the effect sound last started for <paramref name="source"/>. The mapping stays after the sound ends or stops.</summary>
+    /// <summary>State of the sound effect last started for <paramref name="source"/>. The mapping stays after the sound ends or stops.</summary>
     public bool TryGetSourceState(AudioSource? source, out SourceState state)
     {
         state = null!;
@@ -232,7 +291,7 @@ internal sealed class OfflineAudioMixer : IDisposable
     }
 
     /// <summary>
-    /// Stops every effect sound at <paramref name="now"/>, including ones scheduled to start later
+    /// Stops every sound effect at <paramref name="now"/>, including ones scheduled to start later
     /// (AudioManager.StopAllSounds destroys every AudioSource in liveSources, which holds the sources of
     /// AudioManager._Play and scrConductor.PlayWithEndTime). The song voice keeps playing.
     /// </summary>
@@ -269,7 +328,10 @@ internal sealed class OfflineAudioMixer : IDisposable
         }
     }
 
-    /// <summary>Stops waiting for commits and chunks; the render thread's current or next mix throws OperationCanceledException.</summary>
+    /// <summary>
+    /// Stops waiting for commits and chunks; the render thread's current or next mix throws OperationCanceledException.
+    /// May be called from any thread, more than once.
+    /// </summary>
     public void Cancel()
     {
         _cancellation.Cancel();
@@ -280,7 +342,10 @@ internal sealed class OfflineAudioMixer : IDisposable
 
     /// <summary>
     /// Writes the next <paramref name="samplesNeeded"/> output frames (interleaved float, continuing from the previous call).
+    /// Blocks until the main Unity thread has committed the voice samples it needs (<see cref="Commit"/>, <see cref="Complete"/>).
     /// </summary>
+    /// <param name="mixedBuffer">Destination; must hold at least samplesNeeded * channels floats. Values beyond that are untouched.</param>
+    /// <param name="samplesNeeded">Frames (samples per channel) to write.</param>
     /// <exception cref="InvalidOperationException">Chunk loading failed fatally (out of memory or the decoder thread stopped).</exception>
     /// <exception cref="OperationCanceledException">The render was canceled (<see cref="Cancel"/>).</exception>
     public void GenerateAudioForFrame(float[] mixedBuffer, int samplesNeeded)
@@ -289,6 +354,8 @@ internal sealed class OfflineAudioMixer : IDisposable
         {
             if (_disposed) throw new ObjectDisposedException(nameof(OfflineAudioMixer));
 
+            // First call: run voice samples [0, latency) through the filters and discard the output, which is the
+            // zero-filled delay lines. Afterwards output sample n is the filtered voice sample n.
             if (!_primed)
             {
                 _primed = true;
@@ -310,7 +377,7 @@ internal sealed class OfflineAudioMixer : IDisposable
         }
     }
 
-    /// <summary>Mixes voices at samples [first, first + frames) into the reused double buffer, after the main thread committed them.</summary>
+    /// <summary>Mixes voices at samples [first, first + frames) into the reused double buffer, after the main Unity thread committed them.</summary>
     private Span<double> MixBlock(long first, int frames)
     {
         WaitForCommit(first + frames);
@@ -323,6 +390,11 @@ internal sealed class OfflineAudioMixer : IDisposable
         return block;
     }
 
+    /// <summary>
+    /// Waits until the committed sample reaches <paramref name="endSample"/> (exclusive end of the block to mix), checking for
+    /// cancellation every <see cref="CommitWaitMs"/> ms.
+    /// </summary>
+    /// <exception cref="OperationCanceledException">The render was canceled.</exception>
     private void WaitForCommit(long endSample)
     {
         lock (_commitLock)

Util/Audio/SourceState.cs

@@ -21,15 +21,33 @@ namespace ADOFAIRenderer.Util.Audio;
 /// </summary>
 internal sealed class SourceState
 {
+    /// <summary>Start of playback, seconds relative to the render start.</summary>
     private readonly double _start;
+
+    /// <summary>Render time of the last position or pitch change (at least <see cref="_start"/>), seconds.</summary>
     private double _anchorTime;
+
+    /// <summary>Unwrapped clip position at <see cref="_anchorTime"/>, seconds into the clip.</summary>
     private double _anchorPosition;
+
+    /// <summary>Last finite pitch set (reported as is; negative values play as 0).</summary>
     private double _pitch;
+
     private readonly bool _loop;
+
+    /// <summary>Scheduled end time, seconds relative to the render start; infinity when not set.</summary>
     private double _endTime = double.PositiveInfinity;
+
+    /// <summary>True after <see cref="Stop"/>; playback does not resume.</summary>
     private bool _stopped;
+
+    /// <summary>timeSamples reported while not playing: the last value set through time/timeSamples, 0 after Stop.</summary>
     private int _offsetSamples;
+
+    /// <summary>Clip length in seconds.</summary>
     private double _length;
+
+    /// <summary>Clip sample rate in Hz (at least 1), used to convert between time and timeSamples.</summary>
     private int _frequency;
 
     /// <param name="voice">Voice that plays the sound.</param>
@@ -51,6 +69,7 @@ internal sealed class SourceState
         _frequency = Math.Max(1, frequency);
     }
 
+    /// <summary>Voice of the <see cref="VoiceMixer"/> that plays the sound; changes made while playing are queued on it.</summary>
     public Voice Voice { get; }
 
     /// <summary>Takes the clip length and sample rate from the clip of the game AudioSource.</summary>
@@ -69,26 +88,39 @@ internal sealed class SourceState
         Voice.SetEndTime(endTime, now);
     }
 
+    /// <summary>AudioSource.isPlaying at <paramref name="now"/>: not stopped and before both the scheduled end and the natural end.</summary>
     public bool IsPlaying(double now) => !_stopped && now < Math.Min(_endTime, NaturalEnd());
 
+    /// <summary>AudioSource.time at <paramref name="now"/>: clip position in seconds while playing, otherwise 0.</summary>
     public float GetTime(double now) => IsPlaying(now) ? (float)PositionAt(now) : 0f;
 
+    /// <summary>AudioSource.timeSamples at <paramref name="now"/>: floor(position * frequency) while playing, otherwise the stored offset.</summary>
     public int GetTimeSamples(double now) => IsPlaying(now) ? (int)Math.Floor(PositionAt(now) * _frequency) : _offsetSamples;
 
+    /// <summary>AudioSource.pitch: the last finite value set.</summary>
     public float GetPitch() => (float)_pitch;
 
+    /// <summary>
+    /// AudioSource.time setter: stores floor(seconds * frequency) as the offset and, while playing, moves the position to
+    /// <paramref name="seconds"/> (negative values become 0) from <paramref name="now"/> (or from the start when not started yet).
+    /// </summary>
     public void SetTime(float seconds, double now)
     {
         _offsetSamples = (int)Math.Floor((double)seconds * _frequency);
         Seek(seconds, now);
     }
 
+    /// <summary>AudioSource.timeSamples setter: as <see cref="SetTime"/> with samples / frequency seconds.</summary>
     public void SetTimeSamples(int samples, double now)
     {
         _offsetSamples = samples;
         Seek((double)samples / _frequency, now);
     }
 
+    /// <summary>
+    /// AudioSource.pitch setter: ignores NaN and infinity. While playing, the position up to <paramref name="now"/> is kept
+    /// (new anchor) and the voice changes rate at <paramref name="now"/>; otherwise only the reported value changes.
+    /// </summary>
     public void SetPitch(float pitch, double now)
     {
         if (float.IsNaN(pitch) || float.IsInfinity(pitch)) return;
@@ -98,6 +130,7 @@ internal sealed class SourceState
         if (playing) Voice.SetPitch(pitch, now);
     }
 
+    /// <summary>AudioSource.Stop(): stops the voice at <paramref name="now"/> when playing, marks the state stopped and clears the offset.</summary>
     public void Stop(double now)
     {
         if (IsPlaying(now)) Voice.Stop(now);
@@ -105,8 +138,13 @@ internal sealed class SourceState
         _offsetSamples = 0;
     }
 
+    /// <summary>Rate used for playback: <see cref="_pitch"/> with negative values treated as 0 (as in <see cref="Voice.SetPitch"/>).</summary>
     private double PlaybackPitch => Math.Max(0.0, _pitch);
 
+    /// <summary>
+    /// While playing, sets the clip position to <paramref name="seconds"/> (at least 0) from max(now, start) and queues the same
+    /// position change on the voice.
+    /// </summary>
     private void Seek(double seconds, double now)
     {
         if (!IsPlaying(now)) return;
@@ -116,6 +154,7 @@ internal sealed class SourceState
         Voice.SetPosition(position, now);
     }
 
+    /// <summary>Moves the anchor to max(now, start), keeping the current position, before a pitch change.</summary>
     private void Reanchor(double now)
     {
         var time = Math.Max(now, _start);

Util/BundleLoader.cs

@@ -6,9 +6,16 @@ using UnityEngine;
 
 namespace ADOFAIRenderer.Util;
 
+/// <summary>
+/// Loads the Unity asset bundles (fonts, shaders) embedded in the mod DLL as manifest resources. One bundle set is
+/// embedded per platform (Bundle/Win64, Bundle/OSX, Bundle/Linux).
+/// Main thread (AssetBundle loading).
+/// </summary>
 internal static class BundleLoader
 {
+    /// <summary>Resource folder of the running platform: "Win64" on Windows, "OSX" on macOS, "Linux" otherwise.</summary>
     private static readonly string BundlePlatform;
+    /// <summary>The mod assembly that contains the bundle resources.</summary>
     private static readonly Assembly? ExecutingAssembly;
 
     static BundleLoader()
@@ -22,6 +29,16 @@ internal static class BundleLoader
         ExecutingAssembly = Assembly.GetExecutingAssembly();
     }
 
+    /// <summary>
+    /// Loads the bundle stored as manifest resource "ADOFAIRenderer.Bundle.&lt;platform&gt;.&lt;resourcePath&gt;" with
+    /// AssetBundle.LoadFromStream. The resource stream is disposed when this method returns. The caller owns the returned
+    /// bundle.
+    /// Reference: https://docs.unity3d.com/ScriptReference/AssetBundle.LoadFromStream.html
+    /// </summary>
+    /// <param name="resourcePath">Bundle name inside the platform folder, for example "fonts" or "shaders".</param>
+    /// <returns>The loaded bundle, or null when Unity fails to load it.</returns>
+    /// <exception cref="MissingManifestResourceException">The resource is not embedded in the DLL.</exception>
+    /// <exception cref="InvalidOperationException">The executing assembly is not available.</exception>
     public static AssetBundle GetBundle(string resourcePath)
     {
         if (ExecutingAssembly != null)

Util/FFmpeg/FFmpegNativeDecoder.cs

@@ -10,9 +10,19 @@ namespace ADOFAIRenderer.Util.FFmpeg;
 
 /// <summary>
 /// High-performance video decoder that directly invokes FFmpeg native C libraries via P/Invoke.
-/// Supports both GPU hardware-accelerated decoding (D3D11VA, DXVA2, QSV, CUDA, D3D12VA) and
+/// Supports both GPU hardware-accelerated decoding (device types of <see cref="PreferredHwDeviceTypes"/>: D3D11VA, DXVA2,
+/// CUDA, D3D12VA on Windows; VAAPI, CUDA or VideoToolbox on other platforms; others the decoder reports) and
 /// CPU multi-threaded software decoding (FF_THREAD_FRAME) with automatic fallback.
 ///
+/// Used by VideoBGPlayer to decode the background video of a level. Only the first video stream is decoded;
+/// audio and other streams are discarded by the demuxer.
+///
+/// Threading: every public member takes <c>_lock</c>, so calls from different threads are serialized.
+/// Width, Height, FPS, Duration and TotalFrames are set once in the constructor and read without the lock.
+///
+/// Timestamps returned by the TryRead* methods are the presentation times of the stream in seconds
+/// (PTS × stream time base), so a stream with a non-zero start time returns timestamps starting at that time.
+///
 /// ── Architecture &amp; Lifecycle Flow ──────────────────────────────────────────────
 ///
 ///   1. Construction &amp; Demuxing:
@@ -42,6 +52,7 @@ namespace ADOFAIRenderer.Util.FFmpeg;
 ///         - TryReadFrame: sws_scale conversion to RGBA32 with optional vertical flip (vflip).
 ///
 ///   4. Seeking &amp; Scrubbing (SeekToTime / SeekToFrame):
+///      (Short forward distances skip a) and b) and only decode forward; see SeekToTime.)
 ///      a) av_seek_frame: Fast backward keyframe seek.
 ///      b) avcodec_flush_buffers: Clear internal decoder state.
 ///      c) Forward decoding loop: Discards non-target frames without GPU transfer overhead;
@@ -72,7 +83,10 @@ internal sealed unsafe class FFmpegNativeDecoder : IDisposable
     /// </summary>
     private record struct HwConfigCandidate
     {
+        /// <summary>Hardware device type to create with av_hwdevice_ctx_create (AVCodecHWConfig.device_type).</summary>
         public AVHWDeviceType DeviceType;
+
+        /// <summary>Hardware surface pixel format the decoder outputs with this device (AVCodecHWConfig.pix_fmt, e.g. AV_PIX_FMT_D3D11).</summary>
         public AVPixelFormat PixelFormat;
     }
 
@@ -80,9 +94,10 @@ internal sealed unsafe class FFmpegNativeDecoder : IDisposable
     /// Preferred hardware device types in priority order.
     /// The candidates are the hardware configurations the selected decoder reports (avcodec_get_hw_config),
     /// sorted by this list; configurations not in the list follow in reported order.
-    /// Windows: D3D11VA, then DXVA2 (DirectX 9), CUDA and D3D12VA. Other platforms: VAAPI or VideoToolbox.
+    /// Windows: D3D11VA, then DXVA2 (DirectX 9), CUDA and D3D12VA. Linux: CUDA (NVIDIA), then VAAPI. macOS: VideoToolbox.
+    /// A device type that cannot be created on the machine (no driver, wrong platform) fails creation and is skipped.
     /// The QSV entry matches only decoders that report a QSV configuration. The native decoders returned by
-    /// avcodec_find_decoder report DXVA2/D3D11VA/D3D12VA/CUDA/VAAPI/Vulkan in the bundled FFmpeg 8 build;
+    /// avcodec_find_decoder report hwaccel device types such as DXVA2/D3D11VA/D3D12VA/CUDA/VAAPI/Vulkan (depending on the build);
     /// the QSV decoders (h264_qsv, etc.) are separate decoders selected by name.
     /// </summary>
     private static readonly AVHWDeviceType[] PreferredHwDeviceTypes = new[]
@@ -116,6 +131,8 @@ internal sealed unsafe class FFmpegNativeDecoder : IDisposable
 
     /// <summary>
     /// Reference-counted context for the GPU hardware device (D3D11, DXVA2, QSV, CUDA, etc.).
+    /// This class owns one reference; the codec context holds a second one (hw_device_ctx).
+    /// Both are released in Dispose (or when a hardware candidate fails). Null in software decoding.
     /// Reference: https://ffmpeg.org/doxygen/trunk/structAVHWDeviceContext.html
     /// </summary>
     private AVBufferRef* _hwDeviceCtx = null;
@@ -137,6 +154,8 @@ internal sealed unsafe class FFmpegNativeDecoder : IDisposable
 
     /// <summary>
     /// Frame structure holding converted pixel data produced by <c>sws_scale</c> (e.g., RGBA or fallback YUV).
+    /// Owns no pixel memory: during one conversion its data[]/linesize[] point to the caller's output buffers,
+    /// and they are cleared before and after (ClearConvertedFramePointers).
     /// Reference: https://ffmpeg.org/doxygen/trunk/structAVFrame.html
     /// </summary>
     private AVFrame* _pConvertedFrame = null;
@@ -147,6 +166,11 @@ internal sealed unsafe class FFmpegNativeDecoder : IDisposable
     /// Reference: https://ffmpeg.org/doxygen/trunk/structAVFrame.html
     /// </summary>
     private AVFrame* _pCachedFrame = null;
+
+    /// <summary>
+    /// Whether <see cref="_pCachedFrame"/> holds a frame that the next <c>TryRead*</c> call returns
+    /// before any new frame is decoded. Set by DecodeToTarget, cleared when the frame is consumed or dropped.
+    /// </summary>
     private bool _hasCachedFrame;
 
     /// <summary>
@@ -172,7 +196,11 @@ internal sealed unsafe class FFmpegNativeDecoder : IDisposable
     /// </summary>
     private AVCodecContext_get_format? _getFormatDelegate;
 
-    /// <summary>Whether hardware-accelerated decoding is currently active.</summary>
+    /// <summary>
+    /// Whether hardware-accelerated decoding is currently active.
+    /// Set when a hardware candidate is configured; cleared when it fails, or by GetFormat when the stream
+    /// cannot be decoded on the hardware surface format (the decoder then outputs software frames).
+    /// </summary>
     private bool _isHwDecoding;
 
     /// <summary>Hardware device type in use (e.g. D3D11VA, DXVA2, CUDA, QSV).</summary>
@@ -183,6 +211,8 @@ internal sealed unsafe class FFmpegNativeDecoder : IDisposable
 
     /// <summary>
     /// Pixel format of the frame after downloading from GPU surface to system RAM (typically NV12).
+    /// Assumed NV12 when hardware decoding is configured, then updated from every transferred frame
+    /// (e.g. P010 for 10-bit streams). AV_PIX_FMT_NONE in software decoding.
     /// </summary>
     private AVPixelFormat _downloadedPixFmt = AVPixelFormat.AV_PIX_FMT_NONE;
 
@@ -190,11 +220,28 @@ internal sealed unsafe class FFmpegNativeDecoder : IDisposable
     // Playback, Stream &amp; Scaler Synchronization Fields
     // ──────────────────────────────────────────────────────────────
 
+    /// <summary>Index of the decoded video stream in the format context. -1 until a video stream is found.</summary>
     private int _videoStreamIndex = -1;
+
+    /// <summary>
+    /// Index of the frame most recently returned (or skipped while seeking): round(timestamp × FPS) for frames with a timestamp,
+    /// the previous value + 1 for frames without one. 0 after opening.
+    /// </summary>
     private long _currentFrameIndex;
+
+    /// <summary>Time base of the video stream (seconds per PTS unit). Used to convert PTS to seconds and seek targets to PTS.</summary>
     private AVRational _timeBase;
+
+    /// <summary>Whether Open completed. The read and seek methods do nothing until then and after Dispose.</summary>
     private bool _isOpened;
+
+    /// <summary>Whether Dispose has run. Prevents duplicate cleanup.</summary>
     private bool _disposed;
+
+    /// <summary>
+    /// Whether the end of the input has been reached and the decoder was put into draining mode
+    /// (avcodec_send_packet with null). Reset by a keyframe seek (after avcodec_flush_buffers).
+    /// </summary>
     private bool _isDraining;
 
     /// <summary>Number of video packets skipped because the decoder rejected them as invalid data.</summary>
@@ -203,12 +250,21 @@ internal sealed unsafe class FFmpegNativeDecoder : IDisposable
     /// <summary>Number of skipped packets for which a warning is logged.</summary>
     private const int MaxLoggedSkippedPackets = 5;
 
+    /// <summary>Lock object serializing all public members (decoder state and native resources).</summary>
     private readonly object _lock = new();
 
     // Fields to detect SwsContext updates
+    // Parameters the current _pSwsContext was created with; a frame with different values recreates the context.
+    /// <summary>Source pixel format of the current scaler context.</summary>
     private AVPixelFormat _srcPixFmt = AVPixelFormat.AV_PIX_FMT_NONE;
+
+    /// <summary>Destination pixel format of the current scaler context (RGBA, NV12 or YUV420P).</summary>
     private AVPixelFormat _dstPixFmt = AVPixelFormat.AV_PIX_FMT_NONE;
+
+    /// <summary>Source width of the current scaler context in pixels (the destination is always Width × Height).</summary>
     private int _srcWidth;
+
+    /// <summary>Source height of the current scaler context in pixels.</summary>
     private int _srcHeight;
 
     /// <summary>YUV→RGB matrix id (<c>SWS_CS_*</c>) applied to the context. 0 when no matrix is set (non-RGBA output).</summary>
@@ -221,22 +277,31 @@ internal sealed unsafe class FFmpegNativeDecoder : IDisposable
     // Public Properties
     // ──────────────────────────────────────────────────────────────
 
-    /// <summary>Video width in pixels.</summary>
+    /// <summary>
+    /// Video width in pixels (codec context width after opening, or the stream parameters).
+    /// Every output of the TryRead* methods has this width; frames of another size are scaled to it.
+    /// </summary>
     public int Width { get; private set; }
 
-    /// <summary>Video height in pixels.</summary>
+    /// <summary>Video height in pixels. Every output of the TryRead* methods has this height.</summary>
     public int Height { get; private set; }
 
-    /// <summary>Frames per second.</summary>
+    /// <summary>
+    /// Frames per second: r_frame_rate of the stream, else avg_frame_rate, else 30.
+    /// For variable frame rate streams both values are approximations.
+    /// </summary>
     public double FPS { get; private set; }
 
-    /// <summary>Total duration in seconds.</summary>
+    /// <summary>Total duration in seconds (stream duration, else container duration, else 0).</summary>
     public double Duration { get; private set; }
 
-    /// <summary>Estimated total number of frames.</summary>
+    /// <summary>
+    /// Estimated total number of frames: the frame count of the stream header (nb_frames) when present,
+    /// otherwise round(duration × FPS); 0 when the duration is unknown.
+    /// </summary>
     public long TotalFrames { get; private set; }
 
-    /// <summary>Index of the currently read frame.</summary>
+    /// <summary>Index of the currently read frame (the frame most recently returned or skipped; see _currentFrameIndex).</summary>
     public long CurrentFrameIndex
     {
         get
@@ -248,7 +313,7 @@ internal sealed unsafe class FFmpegNativeDecoder : IDisposable
         }
     }
 
-    /// <summary>Current playback time in seconds.</summary>
+    /// <summary>Current playback time in seconds: CurrentFrameIndex / FPS (0 when FPS is not positive).</summary>
     public double CurrentTime
     {
         get
@@ -266,6 +331,9 @@ internal sealed unsafe class FFmpegNativeDecoder : IDisposable
     /// in system RAM (typically <see cref="AVPixelFormat.AV_PIX_FMT_NV12"/>) rather than the GPU surface format
     /// (e.g., D3D11VA, DXVA2, CUDA), allowing seamless binding to Compute Shader NV12 pipelines.
     /// In software mode, returns the codec context's pixel format (e.g., YUV420P).
+    /// Before the first hardware frame is transferred, NV12 is returned as the expected download format;
+    /// the actual format (e.g. P010 for 10-bit video) is known after the first transfer.
+    /// The TryRead* methods convert any decoded format to their output format, so this value only selects the fastest path.
     /// </summary>
     public AVPixelFormat PixelFormat
     {
@@ -287,6 +355,8 @@ internal sealed unsafe class FFmpegNativeDecoder : IDisposable
 
     /// <summary>
     /// Color range of the video stream (MPEG limited [16-235] or JPEG full [0-255]).
+    /// Taken from the codec context, else from the stream parameters; AVCOL_RANGE_UNSPECIFIED when neither carries a tag.
+    /// This property reads the color_range tags only; it does not inspect the pixel format (YUVJ* formats are full range).
     /// </summary>
     public AVColorRange ColorRange
     {
@@ -394,10 +464,14 @@ internal sealed unsafe class FFmpegNativeDecoder : IDisposable
 
     /// <summary>
     /// Initializes a new instance of <see cref="FFmpegNativeDecoder"/> and opens the specified video file.
-    /// Automatically attempts hardware acceleration (D3D11VA, DXVA2, QSV, CUDA), falling back
-    /// to multi-threaded software decoding if unavailable.
+    /// Automatically attempts hardware acceleration (device types reported by the decoder, in the order of
+    /// <see cref="PreferredHwDeviceTypes"/>), falling back to multi-threaded software decoding if unavailable.
     /// </summary>
     /// <param name="videoPath">Absolute or relative file path to the video file.</param>
+    /// <exception cref="Exception">
+    /// The file cannot be opened, has no video stream, or its codec has no decoder or cannot be opened.
+    /// All native resources allocated so far are released before the exception propagates.
+    /// </exception>
     public FFmpegNativeDecoder(string videoPath)
     {
         Open(videoPath);
@@ -425,10 +499,11 @@ internal sealed unsafe class FFmpegNativeDecoder : IDisposable
                 }
 
                 // 2. Retrieve stream information
+                // Reads (and buffers) the start of the file to fill in codec parameters, frame rates and durations.
                 if (ffmpeg.avformat_find_stream_info(_pFormatContext, null) < 0)
                     throw new Exception("Failed to retrieve stream info.");
 
-                // 3. Find primary video stream
+                // 3. Find primary video stream (the first stream whose codec type is video)
                 _videoStreamIndex = -1;
                 for (int i = 0; i < _pFormatContext->nb_streams; i++)
                 {
@@ -456,6 +531,9 @@ internal sealed unsafe class FFmpegNativeDecoder : IDisposable
                 _timeBase = stream->time_base;
 
                 // 4. Calculate FPS
+                // r_frame_rate: lowest frame rate that represents all timestamps accurately (guessed by libavformat).
+                // avg_frame_rate: average frame rate. Both are approximations for variable frame rate streams.
+                // Reference: https://ffmpeg.org/doxygen/trunk/structAVStream.html
                 if (stream->r_frame_rate.num > 0 && stream->r_frame_rate.den > 0)
                 {
                     FPS = ffmpeg.av_q2d(stream->r_frame_rate);
@@ -470,6 +548,8 @@ internal sealed unsafe class FFmpegNativeDecoder : IDisposable
                 }
 
                 // 5. Find decoder by codec ID
+                // avcodec_find_decoder returns the default decoder registered for the ID (e.g. libdav1d for AV1
+                // when the build includes it, which reports no hardware configuration).
                 var codecId = stream->codecpar->codec_id;
                 var decoder = ffmpeg.avcodec_find_decoder(codecId);
                 if (decoder == null)
@@ -480,6 +560,7 @@ internal sealed unsafe class FFmpegNativeDecoder : IDisposable
                 if (_pCodecContext == null)
                     throw new Exception("Failed to allocate codec context.");
 
+                // Copies the stream parameters (size, pixel format, extradata, color tags, ...) into the codec context.
                 if (ffmpeg.avcodec_parameters_to_context(_pCodecContext, stream->codecpar) < 0)
                     throw new Exception("Failed to copy codec parameters.");
 
@@ -492,6 +573,9 @@ internal sealed unsafe class FFmpegNativeDecoder : IDisposable
                     _downloadedPixFmt = AVPixelFormat.AV_PIX_FMT_NONE;
 
                     // Multi-threading settings for improved software decoding performance (auto thread count)
+                    // thread_type = FF_THREAD_FRAME selects frame threading only (several frames decoded in parallel,
+                    // adds one frame of delay per thread); slice threading is not enabled.
+                    // TryInitializeHwDecoder leaves a fresh codec context when every hardware candidate fails.
                     // Reference: https://ffmpeg.org/doxygen/trunk/structAVCodecContext.html
                     _pCodecContext->thread_count = 0;
                     _pCodecContext->thread_type = ffmpeg.FF_THREAD_FRAME;
@@ -505,6 +589,8 @@ internal sealed unsafe class FFmpegNativeDecoder : IDisposable
                 Height = _pCodecContext->height > 0 ? _pCodecContext->height : stream->codecpar->height;
 
                 // 8. Calculate total frames and duration
+                // nb_frames is the frame count stored in the container (0 when unknown);
+                // otherwise the count is estimated from the stream or container duration and FPS.
                 if (stream->nb_frames > 0)
                 {
                     TotalFrames = stream->nb_frames;
@@ -531,6 +617,7 @@ internal sealed unsafe class FFmpegNativeDecoder : IDisposable
                     : _pFormatContext->duration > 0 ? _pFormatContext->duration / (double)ffmpeg.AV_TIME_BASE : 0;
 
                 // 9. Allocate frame and packet buffers
+                // Structures only; pixel buffers are attached by the decoder, av_hwframe_transfer_data or av_frame_move_ref.
                 // Reference: https://ffmpeg.org/doxygen/trunk/group__lavu__frame.html
                 _pDecodedFrame = ffmpeg.av_frame_alloc();
                 _pHwTransferFrame = ffmpeg.av_frame_alloc();
@@ -552,8 +639,14 @@ internal sealed unsafe class FFmpegNativeDecoder : IDisposable
 
     /// <summary>
     /// Searches for supported hardware device configurations via <c>avcodec_get_hw_config</c>,
-    /// creates the appropriate hardware device context (D3D11VA, DXVA2, QSV, CUDA),
+    /// creates the appropriate hardware device context (D3D11VA, DXVA2, QSV, CUDA, VAAPI, ...),
     /// registers the <c>get_format</c> callback, and attempts to open the hardware decoder.
+    ///
+    /// Candidates are tried in the order of <see cref="PreferredHwDeviceTypes"/>, then the remaining reported order.
+    /// When a candidate fails to open, its codec context and device are freed and a fresh codec context
+    /// (with the stream parameters) is allocated for the next candidate or for the software fallback.
+    /// On success, <see cref="_hwDeviceCtx"/>, <see cref="_hwPixFmt"/> and <see cref="_hwDeviceType"/> describe the device
+    /// and the codec context is open.
     /// </summary>
     /// <param name="decoder">Target decoder.</param>
     /// <param name="stream">Source video stream.</param>
@@ -562,6 +655,9 @@ internal sealed unsafe class FFmpegNativeDecoder : IDisposable
     {
         // ReSharper disable once InconsistentNaming
         // Collect all supported hardware configs from decoder
+        // AV_CODEC_HW_CONFIG_METHOD_HW_DEVICE_CTX (0x01): the decoder supports the hardware format through hw_device_ctx,
+        // which has to be set on the codec context before avcodec_open2. Only these configurations are used here.
+        // Reference: https://github.com/FFmpeg/FFmpeg/blob/master/libavcodec/codec.h
         const int AV_CODEC_HW_CONFIG_METHOD_HW_DEVICE_CTX = 0x01;
         var candidates = new List<HwConfigCandidate>();
         for (int i = 0; ; i++)
@@ -616,6 +712,8 @@ internal sealed unsafe class FFmpegNativeDecoder : IDisposable
             // Reference: https://ffmpeg.org/doxygen/trunk/group__lavu__hwcontext.html
             if (candidate.DeviceType == AVHWDeviceType.AV_HWDEVICE_TYPE_QSV)
             {
+                // QSV: first with an explicit child device (D3D11VA on Windows, VAAPI elsewhere),
+                // then without options (FFmpeg selects the child device type).
                 var isWindows = RuntimeInformation.IsOSPlatform(OSPlatform.Windows);
                 string childDeviceName = isWindows ? "d3d11va" : "vaapi";
                 AVDictionary* opts = null;
@@ -631,6 +729,7 @@ internal sealed unsafe class FFmpegNativeDecoder : IDisposable
             }
             else
             {
+                // Default device of the type (device = null: the first / default adapter chosen by FFmpeg).
                 err = ffmpeg.av_hwdevice_ctx_create(&hwDeviceCtx, candidate.DeviceType, null, null, 0);
             }
 
@@ -646,6 +745,7 @@ internal sealed unsafe class FFmpegNativeDecoder : IDisposable
             }
 
             // Assign hardware context and format selection callback
+            // _hwDeviceCtx takes over the reference created above; the codec context receives its own reference.
             _hwDeviceCtx = hwDeviceCtx;
             _hwPixFmt = candidate.PixelFormat;
             _hwDeviceType = candidate.DeviceType;
@@ -663,6 +763,9 @@ internal sealed unsafe class FFmpegNativeDecoder : IDisposable
                 continue;
             }
 
+            // The delegate is kept in a field so that it is not collected while native code can still call it
+            // (FFmpeg.AutoGen marshals it to a function pointer). With thread_count = 1 it is called on the calling
+            // thread inside avcodec_send_packet / avcodec_receive_frame, which run under _lock.
             _getFormatDelegate = GetFormat;
             _pCodecContext->get_format = _getFormatDelegate;
 
@@ -681,7 +784,8 @@ internal sealed unsafe class FFmpegNativeDecoder : IDisposable
                 return true;
             }
 
-            // Failed to open codec with this hardware configuration, clean up and try next
+            // Failed to open codec with this hardware configuration, clean up and try next.
+            // Freeing the codec context releases its hw_device_ctx reference; _hwDeviceCtx holds the last one.
             Melon<RenderMod>.Logger.Warning($"[FFmpegNativeDecoder] avcodec_open2 failed with HW device {candidate.DeviceType}: {GetFFmpegErrorString(openRet)}. Retrying next candidate...");
 
             if (_pCodecContext != null)
@@ -717,8 +821,14 @@ internal sealed unsafe class FFmpegNativeDecoder : IDisposable
     /// Callback invoked by libavcodec during decoding to negotiate the output pixel format.
     /// Confirms the hardware surface format (<see cref="_hwPixFmt"/>) if offered by the decoder,
     /// or falls back to software pixel formats via <c>avcodec_default_get_format</c>.
+    /// Called at the start of decoding and again when stream parameters change (e.g. resolution).
+    /// The fallback clears <see cref="_isHwDecoding"/>; the decoder then outputs frames in system memory
+    /// with the thread count set for hardware decoding (1).
     /// Reference: https://ffmpeg.org/doxygen/trunk/structAVCodecContext.html
     /// </summary>
+    /// <param name="ctx">Codec context negotiating the format.</param>
+    /// <param name="pixFmts">Formats the decoder can output for the stream, terminated by AV_PIX_FMT_NONE (hardware formats first).</param>
+    /// <returns>The selected pixel format.</returns>
     private AVPixelFormat GetFormat(AVCodecContext* ctx, AVPixelFormat* pixFmts)
     {
         for (var p = pixFmts; *p != AVPixelFormat.AV_PIX_FMT_NONE; p++)
@@ -744,9 +854,11 @@ internal sealed unsafe class FFmpegNativeDecoder : IDisposable
     /// then sends it to the decoder via <c>avcodec_send_packet</c>.
     /// A packet that the decoder rejects as invalid data (<c>AVERROR_INVALIDDATA</c>, e.g. a damaged packet)
     /// is skipped and the next packet is read. Any other decoder error is thrown.
+    /// Packets of other streams are discarded (they are normally not returned, see AVDISCARD_ALL in Open).
+    /// Called only after avcodec_receive_frame returned EAGAIN, so avcodec_send_packet accepts the packet.
     /// Reference: https://ffmpeg.org/doxygen/trunk/group__lavc__encdec.html
     /// </summary>
-    /// <returns>True if a video packet was sent; false on EOF.</returns>
+    /// <returns>True if a video packet was sent; false on EOF or on a read error (both end the stream).</returns>
     private bool ReadAndSendPacket()
     {
         while (true)
@@ -757,6 +869,8 @@ internal sealed unsafe class FFmpegNativeDecoder : IDisposable
 
             if (_pPacket->stream_index == _videoStreamIndex)
             {
+                // avcodec_send_packet takes its own reference to (or copy of) the packet data,
+                // so the packet is unreferenced right away for the next av_read_frame.
                 ret = ffmpeg.avcodec_send_packet(_pCodecContext, _pPacket);
                 ffmpeg.av_packet_unref(_pPacket);
 
@@ -785,9 +899,16 @@ internal sealed unsafe class FFmpegNativeDecoder : IDisposable
     /// If the frame is decoded on a GPU hardware surface (D3D11VA, DXVA2, CUDA, QSV),
     /// it is automatically downloaded to system RAM via <c>av_hwframe_transfer_data</c> into <c>_pHwTransferFrame</c>,
     /// preserving presentation timestamps via <c>av_frame_copy_props</c>.
+    ///
+    /// Decode loop: avcodec_receive_frame → on EAGAIN read and send the next packet → retry.
+    /// When the input ends, a null packet switches the decoder to draining mode; the remaining delayed frames
+    /// are returned, then avcodec_receive_frame returns AVERROR_EOF.
+    /// The returned frame (<see cref="_pDecodedFrame"/> or <see cref="_pHwTransferFrame"/>) holds its data until
+    /// the caller unreferences it (av_frame_unref) or the next frame is received.
     /// </summary>
     /// <param name="outFrame">The software frame containing pixel data in system RAM.</param>
     /// <returns>True if a frame was successfully decoded and available; false on EOF or draining.</returns>
+    /// <exception cref="Exception">Decoding, packet sending or the GPU-to-host transfer fails.</exception>
     private bool TryReceiveFrame(out AVFrame* outFrame)
     {
         outFrame = null;
@@ -800,6 +921,9 @@ internal sealed unsafe class FFmpegNativeDecoder : IDisposable
                 // Check if the received frame is on a hardware surface
                 if (_isHwDecoding && _pDecodedFrame->format == (int)_hwPixFmt)
                 {
+                    // av_hwframe_transfer_data with an empty destination frame allocates a system memory buffer
+                    // in the first format the device supports for download (NV12 for 8-bit 4:2:0 on the common APIs).
+                    // Reference: https://ffmpeg.org/doxygen/trunk/group__lavu__hwcontext.html (av_hwframe_transfer_data)
                     ffmpeg.av_frame_unref(_pHwTransferFrame);
                     int transferRet = ffmpeg.av_hwframe_transfer_data(_pHwTransferFrame, _pDecodedFrame, 0);
                     if (transferRet < 0)
@@ -809,6 +933,8 @@ internal sealed unsafe class FFmpegNativeDecoder : IDisposable
                     }
 
                     // Copy presentation timestamp and metadata properties
+                    // (pts, best_effort_timestamp, color tags; av_hwframe_transfer_data copies pixel data only).
+                    // The hardware surface is then released back to the decoder's pool.
                     ffmpeg.av_frame_copy_props(_pHwTransferFrame, _pDecodedFrame);
                     ffmpeg.av_frame_unref(_pDecodedFrame);
 
@@ -822,6 +948,9 @@ internal sealed unsafe class FFmpegNativeDecoder : IDisposable
                 return true;
             }
 
+            // EAGAIN: the decoder needs more input. Feed the next video packet, or start draining at the end of the input.
+            // The return value of the flush call (null packet) is not checked; a failure shows up as an error or EOF
+            // from the next avcodec_receive_frame.
             if (ret == ffmpeg.AVERROR(ffmpeg.EAGAIN))
             {
                 if (_isDraining) return false;
@@ -832,6 +961,7 @@ internal sealed unsafe class FFmpegNativeDecoder : IDisposable
                     ffmpeg.avcodec_send_packet(_pCodecContext, null);
                 }
             }
+            // EOF: every delayed frame has been returned after draining.
             else if (ret == ffmpeg.AVERROR_EOF)
             {
                 return false;
@@ -886,8 +1016,11 @@ internal sealed unsafe class FFmpegNativeDecoder : IDisposable
     /// Lazily initializes or updates the <see cref="SwsContext"/> when source/destination formats, dimensions,
     /// or (for RGBA output) the colorspace / range of the source frame change.
     /// For RGBA output the YUV→RGB matrix and the source range are taken from <paramref name="colorFrame"/>.
+    /// For NV12/YUV420P output no matrix is set; libswscale converts between the formats with its default range handling.
+    /// The destination size is always <see cref="Width"/> × <see cref="Height"/>; SWS_BILINEAR filters scaling and chroma resampling.
     /// Reference: https://ffmpeg.org/doxygen/trunk/group__libsws.html
     /// </summary>
+    /// <exception cref="Exception">sws_getContext cannot create a context for the conversion.</exception>
     /// <param name="srcFormat">Pixel format of the source frame.</param>
     /// <param name="srcWidth">Width of the source frame in pixels.</param>
     /// <param name="srcHeight">Height of the source frame in pixels.</param>
@@ -933,6 +1066,8 @@ internal sealed unsafe class FFmpegNativeDecoder : IDisposable
             throw new Exception($"Failed to initialize SwsContext (src: {srcFormat} {srcWidth}x{srcHeight} -> dst: {dstFormat} {Width}x{Height}).");
         }
 
+        // A new context uses the BT.601 matrix and the range implied by the source pixel format (full for YUVJ*,
+        // limited otherwise); set the frame's matrix and range for YUV → RGBA.
         if (swsColorspace != 0)
         {
             ApplySwsColorspace(swsColorspace, fullRange);
@@ -952,13 +1087,15 @@ internal sealed unsafe class FFmpegNativeDecoder : IDisposable
         int* currentTable;
         int srcRange, dstRange, brightness, contrast, saturation;
 
-        // Returns a negative value when the context cannot change its colorspace details (e.g. YUV to YUV conversion).
+        // A negative return value means the details cannot be read; the context then keeps its default matrix and range.
         if (ffmpeg.sws_getColorspaceDetails(_pSwsContext, &currentInvTable, &srcRange, &currentTable, &dstRange,
                 &brightness, &contrast, &saturation) < 0)
         {
             return;
         }
 
+        // inv_table: coefficients of the source YUV space (used for YUV → RGB); table: coefficients of the destination.
+        // A failure of sws_setColorspaceDetails leaves the defaults of the context and is not reported.
         var coefficients = ffmpeg.sws_getCoefficients(swsColorspace);
         var invTable = new int_array4();
         var table = new int_array4();
@@ -975,6 +1112,8 @@ internal sealed unsafe class FFmpegNativeDecoder : IDisposable
     /// <summary>
     /// Computes presentation timestamp (PTS) in seconds from frame metadata without modifying decoder state.
     /// Used by seeking to inspect candidate frames without falsely incrementing frame indices.
+    /// Uses best_effort_timestamp (libavcodec's estimate from PTS/DTS), else pts, converted with the stream time base.
+    /// A frame without either timestamp gets <see cref="_currentFrameIndex"/> / FPS.
     /// </summary>
     private double GetFrameTimestamp(AVFrame* frame)
     {
@@ -994,6 +1133,7 @@ internal sealed unsafe class FFmpegNativeDecoder : IDisposable
 
     /// <summary>
     /// Computes playback presentation timestamp (PTS) in seconds from frame metadata and updates the frame counter.
+    /// With a timestamp, <see cref="_currentFrameIndex"/> = round(timestamp × FPS); without one, it is incremented by 1.
     /// </summary>
     private double GetTimestampAndUpdateIndex(AVFrame* frame)
     {
@@ -1016,6 +1156,8 @@ internal sealed unsafe class FFmpegNativeDecoder : IDisposable
     /// <summary>
     /// Resets all data plane pointers and strides in <see cref="_pConvertedFrame"/> to zero.
     /// Prevents stale or dangling pointers from previous conversions being retained across frames.
+    /// The frame never owns buffers (buf[] stays empty), so av_frame_free in Dispose does not touch caller memory.
+    /// 8 = AV_NUM_DATA_POINTERS, the size of AVFrame.data / linesize.
     /// </summary>
     private void ClearConvertedFramePointers()
     {
@@ -1034,12 +1176,15 @@ internal sealed unsafe class FFmpegNativeDecoder : IDisposable
     /// <summary>
     /// Reads the next video frame and copies it in 32-bit RGBA format using libswscale.
     /// Safely processes both hardware-downloaded frames (NV12) and software-decoded frames (YUV420P).
+    /// The YUV→RGB matrix and range follow the frame's tags (see InitOrUpdateSwsContext). Frames of another size
+    /// are scaled to Width × Height. A frame cached by a seek is returned first.
     /// </summary>
-    /// <param name="outBuffer">Pointer to destination memory storing RGBA data.</param>
+    /// <param name="outBuffer">Pointer to destination memory storing RGBA data (at least outStride × Height bytes).</param>
     /// <param name="outStride">Byte stride per row of destination memory (Width * 4).</param>
     /// <param name="vflip">Whether to vertically flip the output to match Unity texture coordinates.</param>
     /// <param name="timestamp">Timestamp of the output frame in seconds.</param>
-    /// <returns>True if a frame was successfully retrieved; false on EOF.</returns>
+    /// <returns>True if a frame was successfully retrieved; false on EOF, before opening, after disposal or for a null buffer.</returns>
+    /// <exception cref="Exception">Decoding, transfer or scaler creation fails.</exception>
     public bool TryReadFrame(byte* outBuffer, int outStride, bool vflip, out double timestamp)
     {
         timestamp = 0;
@@ -1063,6 +1208,8 @@ internal sealed unsafe class FFmpegNativeDecoder : IDisposable
             timestamp = GetTimestampAndUpdateIndex(frame);
             InitOrUpdateSwsContext((AVPixelFormat)frame->format, frame->width, frame->height, AVPixelFormat.AV_PIX_FMT_RGBA, frame);
 
+            // Destination: the caller's buffer. vflip uses a negative stride starting at the last row,
+            // so sws_scale writes the rows bottom-up (Unity textures have their origin at the bottom-left).
             ClearConvertedFramePointers();
             if (vflip)
             {
@@ -1082,6 +1229,7 @@ internal sealed unsafe class FFmpegNativeDecoder : IDisposable
                 _pConvertedFrame->data, _pConvertedFrame->linesize
             );
 
+            // Release the decoded (or cached) frame's buffers; the output is now in the caller's buffer.
             ClearConvertedFramePointers();
             ffmpeg.av_frame_unref(frame);
             return true;
@@ -1090,6 +1238,7 @@ internal sealed unsafe class FFmpegNativeDecoder : IDisposable
 
     /// <summary>
     /// Reads the next video frame and copies it in RGBA format to an unmanaged memory pointer.
+    /// Same as the byte* overload.
     /// </summary>
     public bool TryReadFrame(IntPtr outBuffer, int outStride, bool vflip, out double timestamp)
     {
@@ -1098,7 +1247,9 @@ internal sealed unsafe class FFmpegNativeDecoder : IDisposable
 
     /// <summary>
     /// Reads the next video frame and copies it in RGBA format to a Unity NativeArray.
+    /// The rows are tightly packed (stride Width × 4).
     /// </summary>
+    /// <exception cref="ArgumentException">The array is not created or is smaller than Width × Height × 4 bytes.</exception>
     public bool TryReadFrame(NativeArray<byte> outBuffer, bool vflip, out double timestamp)
     {
         if (!outBuffer.IsCreated)
@@ -1119,16 +1270,19 @@ internal sealed unsafe class FFmpegNativeDecoder : IDisposable
 
     /// <summary>
     /// Reads the next video frame and copies its Y and interleaved UV channel data separately in NV12 format.
-    /// When hardware decoding is active (producing NV12 in RAM), CPU color conversion is completely bypassed,
-    /// enabling maximum memory copy throughput directly into Unity textures for Compute Shader processing.
+    /// When hardware decoding is active (producing NV12 in RAM), CPU color conversion is completely bypassed:
+    /// the planes are copied row by row into the caller's buffers (e.g. texture data for Compute Shader processing).
     /// Other formats or mismatched dimensions are automatically converted and scaled to NV12 via libswscale.
+    /// The Y/UV values keep the range of the source (see <see cref="ColorRange"/>); no YUV→RGB conversion happens here.
+    /// A frame cached by a seek is returned first.
     /// </summary>
-    /// <param name="yBuffer">Pointer to destination buffer for Y plane (Width * Height bytes).</param>
+    /// <param name="yBuffer">Pointer to destination buffer for Y plane (yStride × Height bytes; Width bytes per row are written).</param>
     /// <param name="yStride">Row stride in bytes for Y plane.</param>
-    /// <param name="uvBuffer">Pointer to destination buffer for interleaved UV plane (((Width + 1) / 2) * 2 * ((Height + 1) / 2) bytes).</param>
+    /// <param name="uvBuffer">Pointer to destination buffer for interleaved UV plane (uvStride × ceil(Height / 2) bytes; ceil(Width / 2) × 2 bytes per row are written).</param>
     /// <param name="uvStride">Row stride in bytes for UV plane.</param>
     /// <param name="timestamp">Timestamp of the output frame in seconds.</param>
-    /// <returns>True if a frame was successfully retrieved; false on EOF.</returns>
+    /// <returns>True if a frame was successfully retrieved; false on EOF, before opening, after disposal or for a null buffer.</returns>
+    /// <exception cref="Exception">Decoding, transfer or scaler creation fails.</exception>
     // ReSharper disable once InconsistentNaming
     public bool TryReadNV12Frame(
         byte* yBuffer, int yStride,
@@ -1155,6 +1309,8 @@ internal sealed unsafe class FFmpegNativeDecoder : IDisposable
 
             timestamp = GetTimestampAndUpdateIndex(frame);
 
+            // Conversion path: any other format (e.g. YUV420P from software decoding, P010 from 10-bit hardware decoding)
+            // or a frame size different from Width × Height. sws_scale writes directly into the caller's planes.
             if (frame->format != (int)AVPixelFormat.AV_PIX_FMT_NV12 || frame->width != Width || frame->height != Height)
             {
                 InitOrUpdateSwsContext((AVPixelFormat)frame->format, frame->width, frame->height, AVPixelFormat.AV_PIX_FMT_NV12);
@@ -1175,12 +1331,16 @@ internal sealed unsafe class FFmpegNativeDecoder : IDisposable
             }
             else
             {
+                // Direct copy path: NV12 frame of the output size.
+                // The UV plane has ceil(Height / 2) rows of ceil(Width / 2) U/V byte pairs.
                 int w = Width;
                 int h = Height;
                 int uvH = (h + 1) / 2;
                 int uvRowBytes = ((w + 1) / 2) * 2;
 
                 // Copy Y plane (row by row to safely skip linesize GPU padding)
+                // Buffer.MemoryCopy(source, destination, destinationSizeInBytes, bytesToCopy): the destination size
+                // argument is the stride, so a stride smaller than the row width throws instead of overrunning.
                 for (int y = 0; y < h; y++)
                 {
                     Buffer.MemoryCopy(
@@ -1208,6 +1368,7 @@ internal sealed unsafe class FFmpegNativeDecoder : IDisposable
 
     /// <summary>
     /// Reads the next video frame and copies its NV12 Y and interleaved UV channel data to unmanaged memory pointers.
+    /// Same as the byte* overload.
     /// </summary>
     // ReSharper disable once InconsistentNaming
     public bool TryReadNV12Frame(
@@ -1224,7 +1385,9 @@ internal sealed unsafe class FFmpegNativeDecoder : IDisposable
 
     /// <summary>
     /// Reads the next video frame and copies its NV12 Y and interleaved UV channel data into Unity NativeArrays.
+    /// The planes are tightly packed: Y stride Width, UV stride ceil(Width / 2) × 2 with ceil(Height / 2) rows.
     /// </summary>
+    /// <exception cref="ArgumentException">An array is not created or is smaller than its plane.</exception>
     // ReSharper disable once InconsistentNaming
     public bool TryReadNV12Frame(
         NativeArray<byte> yBuffer,
@@ -1261,7 +1424,18 @@ internal sealed unsafe class FFmpegNativeDecoder : IDisposable
     /// Reads the next video frame and copies its planar Y, U, and V channel data separately.
     /// For native YUV420P sources, color conversion is bypassed and memory is copied directly.
     /// Non-YUV420P frames (including NV12 from HW decoding) or mismatched dimensions are converted via libswscale.
+    /// YUVJ420P (full range YUV420P) is copied as well; the values keep the source range (see <see cref="ColorRange"/>).
+    /// A frame cached by a seek is returned first.
     /// </summary>
+    /// <param name="yBuffer">Destination of the Y plane (yStride × Height bytes; Width bytes per row are written).</param>
+    /// <param name="yStride">Row stride in bytes of the Y plane.</param>
+    /// <param name="uBuffer">Destination of the U plane (uStride × ceil(Height / 2) bytes; ceil(Width / 2) bytes per row).</param>
+    /// <param name="uStride">Row stride in bytes of the U plane.</param>
+    /// <param name="vBuffer">Destination of the V plane (same size as U).</param>
+    /// <param name="vStride">Row stride in bytes of the V plane.</param>
+    /// <param name="timestamp">Timestamp of the output frame in seconds.</param>
+    /// <returns>True if a frame was successfully retrieved; false on EOF, before opening, after disposal or for a null buffer.</returns>
+    /// <exception cref="Exception">Decoding, transfer or scaler creation fails.</exception>
     // ReSharper disable once InconsistentNaming
     public bool TryReadYUV420PFrame(
         byte* yBuffer, int yStride,
@@ -1289,6 +1463,7 @@ internal sealed unsafe class FFmpegNativeDecoder : IDisposable
 
             timestamp = GetTimestampAndUpdateIndex(frame);
 
+            // Conversion path: any format other than YUV420P/YUVJ420P, or a frame size different from Width × Height.
             if ((frame->format != (int)AVPixelFormat.AV_PIX_FMT_YUV420P && frame->format != (int)AVPixelFormat.AV_PIX_FMT_YUVJ420P) || frame->width != Width || frame->height != Height)
             {
                 InitOrUpdateSwsContext((AVPixelFormat)frame->format, frame->width, frame->height, AVPixelFormat.AV_PIX_FMT_YUV420P);
@@ -1311,6 +1486,7 @@ internal sealed unsafe class FFmpegNativeDecoder : IDisposable
             }
             else
             {
+                // Direct copy path: each plane row by row (source rows can be padded, linesize ≥ row width).
                 int w = Width;
                 int h = Height;
                 int uvW = (w + 1) / 2;
@@ -1354,6 +1530,7 @@ internal sealed unsafe class FFmpegNativeDecoder : IDisposable
 
     /// <summary>
     /// Reads the next video frame and copies its planar Y, U, and V channel data to unmanaged memory pointers.
+    /// Same as the byte* overload.
     /// </summary>
     // ReSharper disable once InconsistentNaming
     public bool TryReadYUV420PFrame(
@@ -1372,7 +1549,9 @@ internal sealed unsafe class FFmpegNativeDecoder : IDisposable
 
     /// <summary>
     /// Reads the next video frame and copies its planar Y, U, and V channel data into Unity NativeArrays.
+    /// The planes are tightly packed: Y stride Width, U/V stride ceil(Width / 2) with ceil(Height / 2) rows.
     /// </summary>
+    /// <exception cref="ArgumentException">An array is not created or is smaller than its plane.</exception>
     // ReSharper disable once InconsistentNaming
     public bool TryReadYUV420PFrame(
         NativeArray<byte> yBuffer,
@@ -1419,8 +1598,10 @@ internal sealed unsafe class FFmpegNativeDecoder : IDisposable
     /// for the next <c>TryRead*</c> call.
     /// Frames before the target are discarded without GPU-to-host memory transfer; only the target frame is transferred.
     /// When the end of the stream is reached before the target, no frame is cached.
+    /// Every discarded frame updates <see cref="_currentFrameIndex"/>; the cached target frame updates it when it is read.
     /// </summary>
     /// <param name="timeSeconds">Target time in seconds.</param>
+    /// <exception cref="Exception">Decoding or the GPU-to-host transfer of the target frame fails.</exception>
     private void DecodeToTarget(double timeSeconds)
     {
         while (true)
@@ -1451,6 +1632,8 @@ internal sealed unsafe class FFmpegNativeDecoder : IDisposable
                     }
                     else
                     {
+                        // System memory frame: move the buffer references into the cache without copying
+                        // (_pDecodedFrame is left blank for the next receive).
                         ffmpeg.av_frame_unref(_pCachedFrame);
                         ffmpeg.av_frame_move_ref(_pCachedFrame, _pDecodedFrame);
                     }
@@ -1465,6 +1648,7 @@ internal sealed unsafe class FFmpegNativeDecoder : IDisposable
                 continue;
             }
 
+            // Same input feeding and draining as TryReceiveFrame.
             if (ret == ffmpeg.AVERROR(ffmpeg.EAGAIN))
             {
                 if (_isDraining) return;
@@ -1496,8 +1680,12 @@ internal sealed unsafe class FFmpegNativeDecoder : IDisposable
     ///   - Keyframe seek: all other cases (target before the current position, far ahead, or the target frame already read).
     ///     A backward keyframe seek is followed by a forward decode up to the target.
     /// The target frame is transferred and preserved in <see cref="_pCachedFrame"/>; when it is already there, nothing is decoded.
+    /// Negative times are treated as 0. The time is in the timeline of the stream timestamps (a stream that starts at
+    /// a non-zero time has no frame before its start; the first frame is returned for earlier targets).
+    /// When the target is past the last frame, no frame is cached and the next TryRead* call returns false.
     /// </summary>
     /// <param name="timeSeconds">Target time in seconds to seek to.</param>
+    /// <exception cref="Exception">Seeking (including the fallback seek to the start) or decoding fails.</exception>
     public void SeekToTime(double timeSeconds)
     {
         lock (_lock)
@@ -1546,6 +1734,10 @@ internal sealed unsafe class FFmpegNativeDecoder : IDisposable
                 _hasCachedFrame = false;
             }
 
+            // Keyframe seek. With a stream index, the timestamp is in the stream time base.
+            // AVSEEK_FLAG_BACKWARD: seek to the nearest keyframe at or before the target, so that decoding forward
+            // from there reaches the target frame.
+            // Reference: https://ffmpeg.org/doxygen/trunk/group__lavf__decoding.html (av_seek_frame)
             long targetPts = (long)Math.Round(timeSeconds / ffmpeg.av_q2d(_timeBase));
             int ret = ffmpeg.av_seek_frame(_pFormatContext, _videoStreamIndex, targetPts, ffmpeg.AVSEEK_FLAG_BACKWARD);
             if (ret < 0)
@@ -1559,6 +1751,7 @@ internal sealed unsafe class FFmpegNativeDecoder : IDisposable
             }
 
             // Flush decoder internal buffers
+            // Drops the frames buffered from before the seek and ends draining mode, so new packets are accepted again.
             // Reference: https://ffmpeg.org/doxygen/trunk/group__lavc__encdec.html
             ffmpeg.avcodec_flush_buffers(_pCodecContext);
             _isDraining = false;
@@ -1569,9 +1762,9 @@ internal sealed unsafe class FFmpegNativeDecoder : IDisposable
     }
 
     /// <summary>
-    /// Seeks to a specific frame index.
+    /// Seeks to a specific frame index: <see cref="SeekToTime"/> with frameIndex / FPS seconds.
     /// </summary>
-    /// <param name="frameIndex">Target frame index.</param>
+    /// <param name="frameIndex">Target frame index (0-based, in units of 1 / FPS).</param>
     public void SeekToFrame(long frameIndex)
     {
         SeekToTime(frameIndex / FPS);
@@ -1582,7 +1775,8 @@ internal sealed unsafe class FFmpegNativeDecoder : IDisposable
     // ──────────────────────────────────────────────────────────────
 
     /// <summary>
-    /// Translates an FFmpeg integer error code to a readable string using <c>av_strerror</c>.
+    /// Translates an FFmpeg integer error code to a readable string using <c>av_strerror</c>
+    /// (1024-byte stack buffer; "Unknown error (Code: n)" when there is no description).
     /// Reference: https://ffmpeg.org/doxygen/trunk/group__lavu__error.html
     /// </summary>
     private string GetFFmpegErrorString(int errnum)
@@ -1598,6 +1792,10 @@ internal sealed unsafe class FFmpegNativeDecoder : IDisposable
 
     /// <summary>
     /// Releases all native FFmpeg decoder resources, hardware contexts, frame buffers, and scaler structures.
+    /// Safe to call more than once; also called by the constructor on failure and by the finalizer.
+    /// Order: scaler → frames → packet → codec context (releases its hw_device_ctx reference)
+    /// → this object's device reference → input file and format context.
+    /// After Dispose, the read and seek methods return without doing anything.
     /// </summary>
     public void Dispose()
     {
@@ -1681,6 +1879,9 @@ internal sealed unsafe class FFmpegNativeDecoder : IDisposable
         }
     }
 
+    /// <summary>
+    /// Finalizer. Releases the native resources when the decoder was not disposed (runs on the GC finalizer thread).
+    /// </summary>
     ~FFmpegNativeDecoder()
     {
         Dispose();

Util/FFmpeg/VideoEncoder.cs

@@ -6,52 +6,107 @@ using ADOFAIRenderer.Data;
 
 namespace ADOFAIRenderer.Util.FFmpeg;
 
+/// <summary>
+/// Family of a video encoder. Selects the encoder-specific configuration in <see cref="FFmpegNativeEncoder"/>
+/// (input pixel format, hardware device setup, quality option names, speed preset).
+/// </summary>
 [SuppressMessage("ReSharper", "InconsistentNaming")]
 internal enum EncoderKind
 {
+    /// <summary>CPU encoder library linked into FFmpeg (libx264, libx265, libvpx-vp9, libsvtav1, libaom-av1, libvvenc).</summary>
     Software,
+
+    /// <summary>NVIDIA NVENC hardware encoder (*_nvenc).</summary>
     NVENC,
+
+    /// <summary>AMD Advanced Media Framework hardware encoder (*_amf).</summary>
     AMF,
+
+    /// <summary>Intel Quick Sync Video hardware encoder (*_qsv), driven through a QSV hardware device context.</summary>
     QSV,
+
+    /// <summary>Apple VideoToolbox hardware encoder (*_videotoolbox, macOS).</summary>
     VideoToolbox
 }
     
+/// <summary>
+/// Known FFmpeg video encoder: FFmpeg encoder name, output codec, GPU vendor and encoder family.
+///
+/// Instances exist only as the static fields below (the constructor is private); compare them with == or
+/// <see cref="Equals(VideoEncoder)"/>, which compare <see cref="Name"/> case-insensitively.
+/// <see cref="All"/> lists every encoder, and its order is the fallback order used by
+/// GPUUtil.GetPrioritizedEncoders after the encoders of the active GPU vendor.
+///
+/// An entry does not mean that the encoder exists in the loaded FFmpeg build or works on the current machine:
+/// FFmpegNativeEncoder.Start looks each one up with avcodec_find_encoder_by_name and opens it, and skips the
+/// encoders that are missing or fail to open.
+/// Reference: https://ffmpeg.org/ffmpeg-codecs.html (Video Encoders)
+/// </summary>
 [SuppressMessage("ReSharper", "InconsistentNaming")]
 internal sealed class VideoEncoder : IEquatable<VideoEncoder>
 {
     // ReSharper disable MemberCanBePrivate.Global
-        
+
+    // Each field: FFmpeg encoder name, output codec, GPU vendor whose hardware runs it
+    // (Unknown for CPU encoders), encoder family.
+
     // ── H.264 ──
+    /// <summary>NVIDIA NVENC hardware encoder for H.264 (FFmpeg encoder "h264_nvenc").</summary>
     public static readonly VideoEncoder H264_NVENC = new("h264_nvenc", Codec.H264, GPUVendor.NVIDIA, EncoderKind.NVENC);
+    /// <summary>Intel Quick Sync Video hardware encoder for H.264 (FFmpeg encoder "h264_qsv").</summary>
     public static readonly VideoEncoder H264_QSV = new("h264_qsv", Codec.H264, GPUVendor.Intel, EncoderKind.QSV);
+    /// <summary>AMD AMF hardware encoder for H.264 (FFmpeg encoder "h264_amf").</summary>
     public static readonly VideoEncoder H264_AMF = new("h264_amf", Codec.H264, GPUVendor.AMD, EncoderKind.AMF);
+    /// <summary>Apple VideoToolbox hardware encoder for H.264 (FFmpeg encoder "h264_videotoolbox").</summary>
     public static readonly VideoEncoder H264_VideoToolbox = new("h264_videotoolbox", Codec.H264, GPUVendor.Apple, EncoderKind.VideoToolbox);
+    /// <summary>CPU software encoder for H.264 (FFmpeg encoder "libx264").</summary>
     public static readonly VideoEncoder Libx264 = new("libx264", Codec.H264, GPUVendor.Unknown, EncoderKind.Software);
 
     // ── H.265 (HEVC) ──
+    /// <summary>NVIDIA NVENC hardware encoder for H.265 (HEVC) (FFmpeg encoder "hevc_nvenc").</summary>
     public static readonly VideoEncoder HEVC_NVENC = new("hevc_nvenc", Codec.H265, GPUVendor.NVIDIA, EncoderKind.NVENC);
+    /// <summary>Intel Quick Sync Video hardware encoder for H.265 (HEVC) (FFmpeg encoder "hevc_qsv").</summary>
     public static readonly VideoEncoder HEVC_QSV = new("hevc_qsv", Codec.H265, GPUVendor.Intel, EncoderKind.QSV);
+    /// <summary>AMD AMF hardware encoder for H.265 (HEVC) (FFmpeg encoder "hevc_amf").</summary>
     public static readonly VideoEncoder HEVC_AMF = new("hevc_amf", Codec.H265, GPUVendor.AMD, EncoderKind.AMF);
+    /// <summary>Apple VideoToolbox hardware encoder for H.265 (HEVC) (FFmpeg encoder "hevc_videotoolbox").</summary>
     public static readonly VideoEncoder HEVC_VideoToolbox = new("hevc_videotoolbox", Codec.H265, GPUVendor.Apple, EncoderKind.VideoToolbox);
+    /// <summary>CPU software encoder for H.265 (HEVC) (FFmpeg encoder "libx265").</summary>
     public static readonly VideoEncoder Libx265 = new("libx265", Codec.H265, GPUVendor.Unknown, EncoderKind.Software);
 
     // ── VP9 ──
+    // libavcodec has no "vp9_nvenc" encoder (NVENC does not encode VP9), so avcodec_find_encoder_by_name returns null
+    // for this entry and FFmpegNativeEncoder.Start skips it with a "not found" warning.
+    /// <summary>NVIDIA NVENC entry for VP9 (FFmpeg encoder name "vp9_nvenc"); never found in libavcodec, see above.</summary>
     public static readonly VideoEncoder VP9_NVENC = new("vp9_nvenc", Codec.VP9, GPUVendor.NVIDIA, EncoderKind.NVENC);
+    /// <summary>Intel Quick Sync Video hardware encoder for VP9 (FFmpeg encoder "vp9_qsv").</summary>
     public static readonly VideoEncoder VP9_QSV = new("vp9_qsv", Codec.VP9, GPUVendor.Intel, EncoderKind.QSV);
+    /// <summary>CPU software encoder for VP9 (FFmpeg encoder "libvpx-vp9").</summary>
     public static readonly VideoEncoder LibvpxVP9 = new("libvpx-vp9", Codec.VP9, GPUVendor.Unknown, EncoderKind.Software);
 
     // ── AV1 ──
+    /// <summary>NVIDIA NVENC hardware encoder for AV1 (FFmpeg encoder "av1_nvenc").</summary>
     public static readonly VideoEncoder AV1_NVENC = new("av1_nvenc", Codec.AV1, GPUVendor.NVIDIA, EncoderKind.NVENC);
+    /// <summary>Intel Quick Sync Video hardware encoder for AV1 (FFmpeg encoder "av1_qsv").</summary>
     public static readonly VideoEncoder AV1_QSV = new("av1_qsv", Codec.AV1, GPUVendor.Intel, EncoderKind.QSV);
+    /// <summary>AMD AMF hardware encoder for AV1 (FFmpeg encoder "av1_amf").</summary>
     public static readonly VideoEncoder AV1_AMF = new("av1_amf", Codec.AV1, GPUVendor.AMD, EncoderKind.AMF);
+    /// <summary>CPU software encoder for AV1 (FFmpeg encoder "libsvtav1").</summary>
     public static readonly VideoEncoder LibSvtAv1 = new("libsvtav1", Codec.AV1, GPUVendor.Unknown, EncoderKind.Software);
+    /// <summary>CPU software encoder for AV1 (FFmpeg encoder "libaom-av1").</summary>
     public static readonly VideoEncoder LibAomAv1 = new("libaom-av1", Codec.AV1, GPUVendor.Unknown, EncoderKind.Software);
 
     // ── VVC ──
+    /// <summary>CPU software encoder for H.266 (VVC) (FFmpeg encoder "libvvenc").</summary>
     public static readonly VideoEncoder LibVvenc = new("libvvenc", Codec.VVC, GPUVendor.Unknown, EncoderKind.Software);
         
     // ReSharper restore MemberCanBePrivate.Global
 
+    /// <summary>
+    /// Every known encoder, grouped by codec. Within a codec the order is NVENC → QSV → AMF → VideoToolbox → software
+    /// (for the families the codec has); GPUUtil.GetPrioritizedEncoders keeps this order for the encoders that do not
+    /// belong to the active GPU vendor.
+    /// </summary>
     public static readonly IReadOnlyList<VideoEncoder> All = new[]
     {
         H264_NVENC, H264_QSV, H264_AMF, H264_VideoToolbox, Libx264,
@@ -61,15 +116,26 @@ internal sealed class VideoEncoder : IEquatable<VideoEncoder>
         LibVvenc
     };
 
+    /// <summary>Lookup table of <see cref="All"/> by <see cref="Name"/> (case-insensitive), used by <see cref="FromName"/>.</summary>
     private static readonly Dictionary<string, VideoEncoder> ByName =
         All.ToDictionary(e => e.Name, StringComparer.OrdinalIgnoreCase);
 
+    /// <summary>FFmpeg encoder name passed to avcodec_find_encoder_by_name (e.g. "h264_nvenc", "libx264").</summary>
     public string Name { get; }
+
+    /// <summary>Video codec of the bitstream the encoder produces.</summary>
     public Codec Codec { get; }
+
+    /// <summary>GPU vendor whose hardware runs the encoder. <see cref="GPUVendor.Unknown"/> for CPU (software) encoders.</summary>
     public GPUVendor Vendor { get; }
+
+    /// <summary>Encoder family (software or hardware API).</summary>
     public EncoderKind Kind { get; }
+
+    /// <summary>True for every family except <see cref="EncoderKind.Software"/>.</summary>
     public bool IsHardware => Kind != EncoderKind.Software;
 
+    /// <summary>Creates an entry. Used only by the static fields of this class.</summary>
     private VideoEncoder(string name, Codec codec, GPUVendor vendor, EncoderKind kind)
     {
         Name = name;
@@ -78,36 +144,46 @@ internal sealed class VideoEncoder : IEquatable<VideoEncoder>
         Kind = kind;
     }
 
+    /// <summary>
+    /// Returns the known encoder with the given FFmpeg name (case-insensitive),
+    /// or null when <paramref name="name"/> is null, empty or not in <see cref="All"/>.
+    /// </summary>
     public static VideoEncoder? FromName(string name)
     {
         return string.IsNullOrEmpty(name) ? null : ByName.GetValueOrDefault(name);
     }
 
+    /// <summary>True when <paramref name="other"/> is the same entry or has the same <see cref="Name"/> (case-insensitive).</summary>
     public bool Equals(VideoEncoder other)
     {
         if (ReferenceEquals(null, other)) return false;
         return ReferenceEquals(this, other) || string.Equals(Name, other.Name, StringComparison.OrdinalIgnoreCase);
     }
 
+    /// <summary>True when <paramref name="obj"/> is a <see cref="VideoEncoder"/> equal to this one (see <see cref="Equals(VideoEncoder)"/>).</summary>
     public override bool Equals(object? obj)
     {
         return ReferenceEquals(this, obj) || obj is VideoEncoder other && Equals(other);
     }
 
+    /// <summary>Case-insensitive hash of <see cref="Name"/>, consistent with <see cref="Equals(VideoEncoder)"/>.</summary>
     public override int GetHashCode()
     {
         return StringComparer.OrdinalIgnoreCase.GetHashCode(Name);
     }
 
+    /// <summary>Value equality through <see cref="object.Equals(object, object)"/>; two null operands are equal.</summary>
     public static bool operator ==(VideoEncoder left, VideoEncoder right)
     {
         return Equals(left, right);
     }
 
+    /// <summary>Negation of the <c>==</c> operator.</summary>
     public static bool operator !=(VideoEncoder left, VideoEncoder right)
     {
         return !Equals(left, right);
     }
 
+    /// <summary>Returns the FFmpeg encoder name (<see cref="Name"/>).</summary>
     public override string ToString() => Name;
 }

Util/FileUtil.cs

@@ -2,8 +2,15 @@
 
 namespace ADOFAIRenderer.Util;
 
+/// <summary>File system helpers.</summary>
 internal static class FileUtil
 {
+    /// <summary>
+    /// Creates <paramref name="path"/> and its missing parent directories when it does not exist.
+    /// Exceptions of Directory.CreateDirectory are not caught (for example ArgumentException for an empty path,
+    /// IOException or UnauthorizedAccessException when the directory cannot be created).
+    /// </summary>
+    /// <param name="path">Directory path, absolute or relative to the current directory.</param>
     public static void CreateDirectory(string path)
     {
         if (!Directory.Exists(path)) Directory.CreateDirectory(path);

Util/FrameReader.cs

@@ -13,25 +13,61 @@ using UnityEngine.Rendering;
 
 namespace ADOFAIRenderer.Util
 {
+    /// <summary>
+    /// GPU capture of rendered frames for the encoder. For each requested frame it optionally converts the RGBA texture to
+    /// the encoder's YUV 4:2:0 layout with a compute shader (ColorConversion.compute from the mod's asset bundle, kernels
+    /// CSMain_NV12 / CSMain_YUV420P), then reads the result back asynchronously (AsyncGPUReadback.RequestIntoNativeArray)
+    /// into a persistent native buffer and adds it to RenderManager.ImageQueue under its video frame index.
+    /// When the shader or the kernel for the pixel format is unavailable, the RGBA texture is read back unchanged and the
+    /// encoder converts it (IsColorConverted = false).
+    /// <para>
+    /// Each request uses a <see cref="ReadbackRequestState"/> from a pool (16 created up front, more allocated when the pool
+    /// is empty). A state stays out of the pool from the request until the render thread has sent its frame
+    /// (RenderManager.SendVideoFrame, then <see cref="RecycleState"/>) or the frame was dropped.
+    /// </para>
+    /// <para>
+    /// Threads: requests and readback completions run on the main Unity thread; <see cref="RecycleState"/> is also called by
+    /// the render thread. The pool and the disposed flag are guarded by _poolLock. One instance per render, created in
+    /// RenderManager.SetupPlay with the pixel format of the opened encoder.
+    /// </para>
+    /// </summary>
     internal class FrameReader : IDisposable
     {
+        // Property IDs of the compute shader parameters: source texture, output buffer and frame size in pixels.
         private static readonly int Height = Shader.PropertyToID("Height");
         private static readonly int Width = Shader.PropertyToID("Width");
         private static readonly int DestinationBuffer = Shader.PropertyToID("DestinationBuffer");
         private static readonly int SourceTexture = Shader.PropertyToID("SourceTexture");
+        /// <summary>Number of readback states created by InitializePool.</summary>
         private const int InitialBufferSize = 16;
         
+        /// <summary>States that are free for a new request. Guarded by _poolLock.</summary>
         private readonly Stack<ReadbackRequestState> _statePool = new();
+        /// <summary>Every state created by this reader (free, in flight or holding a queued frame), for Dispose. Guarded by _poolLock.</summary>
         private readonly List<ReadbackRequestState> _allocatedStates = new();
+        /// <summary>Lock for _statePool, _allocatedStates, _isInitialized, _isDisposed and ReadbackRequestState.IsInFlight.</summary>
         private readonly object _poolLock = new();
+        /// <summary>True after InitializePool; false again after Dispose (RecycleState then disposes returned states).</summary>
         private bool _isInitialized;
+        /// <summary>Set by Dispose. Completions and recycles that arrive afterwards dispose their state.</summary>
         private volatile bool _isDisposed;
 
+        /// <summary>Color conversion compute shader from the asset bundle (ModAssets.ColorConversionShader); null when not loaded.</summary>
         private readonly ComputeShader? _computeShader;
+        /// <summary>Kernel index for the target pixel format; -1 when the format has no kernel or the kernel was not found.</summary>
         private readonly int _kernelIndex = -1;
+        /// <summary>True when frames are converted to YUV on the GPU (shader and kernel available).</summary>
         private readonly bool _useGPUConversion;
+        /// <summary>Pixel format of the read-back data: the target format with GPU conversion, AV_PIX_FMT_RGBA otherwise.</summary>
         private readonly AVPixelFormat _expectedFormat;
 
+        /// <summary>
+        /// Selects the conversion kernel for <paramref name="targetFormat"/> and fills the state pool.
+        /// </summary>
+        /// <param name="targetFormat">
+        /// Pixel format of the encoder input (FFmpegNativeEncoder.SelectedPixelFormat). NV12 and YUV420P use GPU conversion;
+        /// any other format falls back to RGBA readback.
+        /// </param>
         public FrameReader(AVPixelFormat targetFormat)
         {
             _computeShader = ModAssets.ColorConversionShader;
@@ -57,6 +93,7 @@ namespace ADOFAIRenderer.Util
             InitializePool();
         }
 
+        /// <summary>Creates InitialBufferSize states once. Their buffers are allocated on first use (ReadbackRequestState.Setup).</summary>
         private void InitializePool()
         {
             lock (_poolLock)
@@ -83,6 +120,15 @@ namespace ADOFAIRenderer.Util
             return _useGPUConversion ? pixels * 3 / 2 : pixels * 4;
         }
 
+        /// <summary>
+        /// Requests the capture of <paramref name="texture"/> as video frame <paramref name="currentFrame"/>. Does nothing
+        /// outside the Render stage. Main thread.
+        /// With GPU conversion, the compute kernel writes the YUV data of the texture into the state's ComputeBuffer and that
+        /// buffer is read back; otherwise the texture itself is read back as RGBA. The buffers are sized from the texture
+        /// dimensions of this call. The result arrives in OnReadbackComplete.
+        /// </summary>
+        /// <param name="texture">Frame to capture (game frame or the output of the frame hooks).</param>
+        /// <param name="currentFrame">Video frame index; the key of the frame in ImageQueue.</param>
         public void RequestFrameCapture(Texture texture, long currentFrame)
         {
             if (!RenderManager.IsCapturingActive) return;
@@ -113,6 +159,8 @@ namespace ADOFAIRenderer.Util
                 _computeShader.SetInt(Width, texture.width);
                 _computeShader.SetInt(Height, texture.height);
 
+                // Thread group counts cover the frame in tiles of 32 x 16 pixels (NV12) or 64 x 16 pixels (YUV420P), rounded up.
+            // The tile size is the area one thread group of the ColorConversion.compute kernels processes.
                 var threadGroupsX = _expectedFormat == AVPixelFormat.AV_PIX_FMT_NV12
                     ? (texture.width + 31) / 32
                     : (texture.width + 63) / 64;
@@ -120,6 +168,8 @@ namespace ADOFAIRenderer.Util
 
                 _computeShader.Dispatch(_kernelIndex, threadGroupsX, threadGroupsY, 1);
 
+                // The native buffer must not be disposed until the request completes; Dispose skips states that are in flight.
+                // Reference: https://docs.unity3d.com/ScriptReference/Rendering.AsyncGPUReadback.RequestIntoNativeArray.html
                 AsyncGPUReadback.RequestIntoNativeArray(
                     ref state.NativeBuffer, state.GPUBuffer, state.CachedCallback
                 );
@@ -136,6 +186,17 @@ namespace ADOFAIRenderer.Util
             }
         }
 
+        /// <summary>
+        /// Completion of a readback request (through ReadbackRequestState.CachedCallback).
+        /// <list type="bullet">
+        /// <item>Reader disposed: the state is disposed.</item>
+        /// <item>Render aborted: the state is returned to the pool and nothing is queued.</item>
+        /// <item>Readback error: a black frame (managed buffer) is queued under the same index, so the render thread does not
+        /// wait forever for the missing index, and the state is returned to the pool.</item>
+        /// <item>Success: the state's native buffer is queued without copying; the state stays out of the pool until the
+        /// render thread has encoded the frame.</item>
+        /// </list>
+        /// </summary>
         internal void OnReadbackComplete(ReadbackRequestState state, AsyncGPUReadbackRequest request)
         {
             var frame = state.FrameIndex;
@@ -227,6 +288,10 @@ namespace ADOFAIRenderer.Util
             return frame;
         }
 
+        /// <summary>
+        /// Returns a state to the pool after its frame was sent or dropped, or disposes it when the reader is disposed.
+        /// Called by the render thread (after sending) and by the main Unity thread (abort, errors, queue cleanup).
+        /// </summary>
         internal void RecycleState(ReadbackRequestState state)
         {
             lock (_poolLock)
@@ -242,6 +307,10 @@ namespace ADOFAIRenderer.Util
             }
         }
         
+        /// <summary>
+        /// Adds the frame to RenderManager.ImageQueue under <paramref name="frame"/> (replacing a frame with the same index)
+        /// and wakes the render thread.
+        /// </summary>
         private static void PushToQueue(long frame, RenderManager.CapturedFrame capturedFrame)
         {
             if (!RenderManager.Instance) return;
@@ -252,6 +321,11 @@ namespace ADOFAIRenderer.Util
             RenderManager.Instance.FrameAvailableEvent.Set();
         }
         
+        /// <summary>
+        /// Disposes every state that is not in flight and clears the pool. States in flight are disposed when their
+        /// readback completes. States still referenced by frames in ImageQueue are disposed too, so callers clear the queue
+        /// first (RenderManager.StopFFmpeg / RestoreRenderEnvironment). Main thread.
+        /// </summary>
         public void Dispose()
         {
             lock (_poolLock)
@@ -269,20 +343,38 @@ namespace ADOFAIRenderer.Util
         }
     }
 
+    /// <summary>
+    /// One reusable capture slot of <see cref="FrameReader"/>: the persistent native buffer the readback writes into, the
+    /// ComputeBuffer the conversion kernel writes (GPU conversion only), and the metadata of the frame it currently holds.
+    /// The buffers are kept between frames and reallocated only when the frame size or conversion mode changes.
+    /// </summary>
     internal class ReadbackRequestState : IDisposable
     {
+        /// <summary>Reader that receives the completion and owns the pool.</summary>
         private readonly FrameReader _owner;
+        /// <summary>Video frame index of the current request; -1 while the state is free.</summary>
         public long FrameIndex { get; private set; }
+        /// <summary>
+        /// Persistent native buffer receiving the readback: Width x Height x 3 / 2 bytes of YUV 4:2:0 with GPU conversion,
+        /// Width x Height x 4 bytes of RGBA otherwise. Read by the render thread through CapturedFrame.NativePointer.
+        /// </summary>
         public NativeArray<byte> NativeBuffer;
+        /// <summary>True between the request and its completion. Written under FrameReader._poolLock.</summary>
         public bool IsInFlight { get; internal set; }
 
+        /// <summary>Raw ComputeBuffer (4-byte elements) the conversion kernel writes; null without GPU conversion.</summary>
         public ComputeBuffer? GPUBuffer;
+        /// <summary>True when the current frame is converted to YUV on the GPU.</summary>
         public bool IsGPUConversion { get; private set; }
+        /// <summary>Width of the current frame in pixels.</summary>
         public int Width { get; private set; }
+        /// <summary>Height of the current frame in pixels.</summary>
         public int Height { get; private set; }
 
+        /// <summary>Completion delegate created once per state, so a request does not allocate a new delegate.</summary>
         public readonly Action<AsyncGPUReadbackRequest> CachedCallback;
 
+        /// <summary>Creates a free state without buffers.</summary>
         public ReadbackRequestState(FrameReader owner)
         {
             _owner = owner;
@@ -290,6 +382,17 @@ namespace ADOFAIRenderer.Util
             FrameIndex = -1;
         }
 
+        /// <summary>
+        /// Prepares the state for a request: stores the frame metadata and (re)allocates the buffers when their size differs.
+        /// The native buffer holds width x height x 3 / 2 bytes with GPU conversion, otherwise <paramref name="bufferSize"/>.
+        /// The ComputeBuffer holds the same number of bytes as 4-byte elements (byte count / 4, rounded down).
+        /// </summary>
+        /// <param name="frameIndex">Video frame index of the request.</param>
+        /// <param name="bufferSize">Readback size in bytes for RGBA readback (width x height x 4).</param>
+        /// <param name="isGPUConversion">Whether the kernel converts the frame to YUV.</param>
+        /// <param name="pixelFormat">Pixel format of the read-back data (not used by this method).</param>
+        /// <param name="width">Frame width in pixels.</param>
+        /// <param name="height">Frame height in pixels.</param>
         public void Setup(long frameIndex, int bufferSize, bool isGPUConversion, AVPixelFormat pixelFormat, int width, int height)
         {
             FrameIndex = frameIndex;
@@ -320,16 +423,19 @@ namespace ADOFAIRenderer.Util
             }
         }
 
+        /// <summary>Readback completion; forwards to FrameReader.OnReadbackComplete.</summary>
         private void OnComplete(AsyncGPUReadbackRequest request)
         {
             _owner.OnReadbackComplete(this, request);
         }
 
+        /// <summary>Marks the state as free (FrameIndex -1). The buffers are kept for the next request.</summary>
         public void Recycle()
         {
             FrameIndex = -1;
         }
 
+        /// <summary>Releases the native buffer and the ComputeBuffer.</summary>
         public void Dispose()
         {
             if (NativeBuffer.IsCreated) NativeBuffer.Dispose();

Util/GPUUtil.cs

@@ -10,27 +10,48 @@ using UnityEngine;
 
 namespace ADOFAIRenderer.Util;
 
+/// <summary>
+/// GPU vendor, used to try the hardware encoders of the active GPU first (VideoEncoder.Vendor). <c>Unknown</c> is
+/// also the vendor of the software encoders.
+/// </summary>
 [SuppressMessage("ReSharper", "InconsistentNaming")]
 internal enum GPUVendor
 {
     Unknown, NVIDIA, AMD, Intel, Apple
 }
     
+/// <summary>
+/// Detection of the active GPU vendor and the NVIDIA driver version, and the encoder try order derived from the vendor.
+/// Results are cached for the game session. Main thread (SystemInfo is read on first use).
+/// </summary>
 internal static class GPUUtil
 {
+    // Device name patterns (SystemInfo.graphicsDeviceName) of the GPU families recognized per vendor. A name that matches
+    // none of them gives GPUVendor.Unknown (Apple on macOS), which only affects the encoder try order.
+    // NVIDIA: "NVIDIA GeForce RTX/GTX <number>" with optional SUPER / Ti / Ti SUPER, memory size, "Laptop GPU" and a
+    // "/PCIe/SSE2" suffix.
     private const string NvidiaPattern = 
         @"^NVIDIA GeForce [RG]TX [0-9]+(?> SUPER| Ti(?> SUPER)?)?(?> [0-9]+GB)?(?> Laptop GPU)?(?>/PCIe/SSE2)?$";
 
+    // Intel: "Intel(R) UHD/HD Graphics <number>" or "Intel(R) Arc(TM) <A-C><number> Graphics", with an optional
+    // parenthesized suffix.
     private const string IntelPattern =
         @"^Intel(?>\(R\))? (?>U?HD Graphics [0-9]+|Arc\(TM\) [A-C][0-9]+ Graphics)(?> \([^)]+\))?$";
 
+    // AMD: "AMD Radeon RX <number>" with an optional " XT".
     // ReSharper disable once InconsistentNaming
     private const string AMDPattern =
         @"^AMD Radeon RX [0-9]+(?> XT)?$";
 
+    /// <summary>Vendor found by the first GetActiveGPUVendor call.</summary>
     private static GPUVendor _cachedVendor = GPUVendor.Unknown;
+    /// <summary>True once _cachedVendor is set.</summary>
     private static bool _hasCachedVendor;
 
+    /// <summary>
+    /// Vendor of the GPU Unity renders with: the device name is matched against the NVIDIA, Intel and AMD patterns in
+    /// that order; on macOS an unmatched name gives Apple; otherwise Unknown. Logs the device name once.
+    /// </summary>
     private static GPUVendor GetActiveGPUVendor()
     {
         if (_hasCachedVendor) return _cachedVendor;
@@ -72,9 +93,21 @@ internal static class GPUUtil
         return _cachedVendor;
     }
 
+    /// <summary>Result of the first GetNvidiaDriverVersion call (null when not available).</summary>
     private static double? _cachedNvidiaVersion;
+    /// <summary>True once _cachedNvidiaVersion is set.</summary>
     private static bool _hasCachedNvidiaVersion;
 
+    /// <summary>
+    /// NVIDIA driver version in NVIDIA's numbering (for example 561.09), or null when the active GPU is not detected as
+    /// NVIDIA or no version can be found. The result is cached.
+    /// <para>
+    /// The version is derived from a four-part Windows driver version a.b.c.d as ((c mod 10) x 10000 + d) / 100,
+    /// for example 31.0.15.6109 gives 561.09. It is read from SystemInfo.graphicsDeviceVersion when that string contains a
+    /// four-part number, otherwise (Windows only) from the DriverVersion value of the first display adapter entry whose
+    /// ProviderName contains "NVIDIA" under the display adapter class key of the registry.
+    /// </para>
+    /// </summary>
     public static double? GetNvidiaDriverVersion()
     {
         if (_hasCachedNvidiaVersion) return _cachedNvidiaVersion;
@@ -103,6 +136,9 @@ internal static class GPUUtil
 
         // 2. Fallback to Windows Registry (only on Windows NT platforms via RegistryUtil)
         if (System.Environment.OSVersion.Platform != System.PlatformID.Win32NT) return null;
+        // Device class key of display adapters (class GUID {4d36e968-e325-11ce-bfc1-08002be10318}); each numbered subkey is
+        // one installed adapter driver.
+        // Reference: https://learn.microsoft.com/en-us/windows-hardware/drivers/install/system-defined-device-setup-classes-available-to-vendors
         const string classKey = @"SYSTEM\CurrentControlSet\Control\Class\{4d36e968-e325-11ce-bfc1-08002be10318}";
         var subkeys = RegistryUtil.GetHKLMSubKeyNames(classKey);
         if (subkeys == null) return null;
@@ -130,6 +166,12 @@ internal static class GPUUtil
         return null;
     }
 
+    /// <summary>
+    /// Encoders for <paramref name="codec"/> in the order they are tried: the encoders of the active GPU vendor first,
+    /// then all others in VideoEncoder.All order (hardware encoders of other vendors and the software encoders).
+    /// </summary>
+    /// <param name="codec">Video codec.</param>
+    /// <param name="forceSoftware">When true, only the software encoders of the codec are returned.</param>
     public static List<VideoEncoder> GetPrioritizedEncoders(Codec codec, bool forceSoftware = false)
     {
         var encoders = VideoEncoder.All.Where(e => e.Codec == codec).ToList();

Util/OS/FolderDialogUtil.cs

@@ -10,12 +10,49 @@ using MelonLoader;
 
 namespace ADOFAIRenderer.Util.OS;
 
+/// <summary>
+/// Native "select folder" dialog used to choose the render output directory.
+/// <para>
+/// - <b>Windows</b>: the shell's <c>IFileOpenDialog</c> (COM, <c>FOS_PICKFOLDERS</c>) on a dedicated STA thread owned by the
+///   game window; when it cannot be created or shown, the legacy <c>SHBrowseForFolderW</c> dialog.
+/// </para>
+/// <para>- <b>macOS</b>: <c>osascript</c> running AppleScript <c>choose folder</c>.</para>
+/// <para>
+/// - <b>Linux</b>: <c>zenity --file-selection --directory</c>; when zenity does not return an existing directory (not installed,
+///   cancelled or failed), <c>kdialog --getexistingdirectory</c>.
+/// </para>
+/// <para>
+/// The dialog runs off the main Unity thread so the game keeps rendering frames while it is open. Only one dialog can be open
+/// at a time. Failures are reported to the callback as null (same as cancel); exceptions are logged as warnings, except a
+/// zenity start failure, which silently moves on to kdialog.
+/// </para>
+/// </summary>
 [SuppressMessage("ReSharper", "InconsistentNaming")]
 [SuppressMessage("ReSharper", "UnusedMember.Local")]
 internal static class FolderDialogUtil
 {
+    // 1 while a dialog is open, 0 otherwise. Set with Interlocked.CompareExchange in OpenFolderBrowser and reset by the
+    // dialog worker before it dispatches the result.
     private static int _isDialogOpen;
 
+    /// <summary>
+    /// Opens the folder selection dialog asynchronously and returns immediately.
+    /// <para>
+    /// When a dialog is already open, logs a message and returns without opening another one; <paramref name="onSelected"/>
+    /// is not called in that case. Otherwise the dialog runs on a background thread (Windows: new STA thread
+    /// "FolderDialog-Win"; macOS/Linux: thread pool task) and <paramref name="onSelected"/> receives the result.
+    /// </para>
+    /// <para>
+    /// Callback thread: when the caller has a <see cref="SynchronizationContext"/> (the main Unity thread has one), the callback
+    /// is posted to it and runs on the caller's thread; otherwise it runs on the dialog thread. Exceptions thrown by the
+    /// callback are caught and logged.
+    /// </para>
+    /// <para>On platforms other than Windows, macOS and Linux the callback receives null.</para>
+    /// </summary>
+    /// <param name="initialDirectory">Folder shown first; ignored when empty or not an existing directory.</param>
+    /// <param name="onSelected">
+    /// Receives the absolute path of the selected existing directory, or null when the user cancelled or the dialog failed.
+    /// </param>
     public static void OpenFolderBrowser(string initialDirectory, Action<string?> onSelected)
     {
         if (Interlocked.CompareExchange(ref _isDialogOpen, 1, 0) != 0)
@@ -24,12 +61,18 @@ internal static class FolderDialogUtil
             return;
         }
 
+        // Captured on the calling thread so the result can be posted back to it.
         var syncContext = SynchronizationContext.Current;
 
         if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
         {
+            // Resolved on the calling thread: GetActiveWindow only returns a window attached to the calling thread's
+            // message queue.
             var ownerHandle = GetGameWindowHandle();
 
+            // Both dialogs run on a single-threaded apartment (STA) thread with OLE initialized; SHBrowseForFolder with
+            // BIF_NEWDIALOGSTYLE fails in a multithreaded apartment.
+            // Reference: https://learn.microsoft.com/en-us/windows/win32/api/shlobj_core/ns-shlobj_core-browseinfow
             var thread = new Thread(() =>
             {
                 string? selected = null;
@@ -45,6 +88,8 @@ internal static class FolderDialogUtil
                 }
                 finally
                 {
+                    // OleInitialize returns S_OK or S_FALSE (already initialized) on success; each successful call is
+                    // balanced by one OleUninitialize.
                     if (oleHr >= 0)
                     {
                         try
@@ -98,6 +143,13 @@ internal static class FolderDialogUtil
         }
     }
 
+    /// <summary>
+    /// Delivers the dialog result: posts <paramref name="onSelected"/> to <paramref name="syncContext"/> when it is not null,
+    /// otherwise invokes it on the current (dialog) thread. Callback exceptions are caught and logged.
+    /// </summary>
+    /// <param name="syncContext">Synchronization context of the thread that opened the dialog, or null.</param>
+    /// <param name="onSelected">Result callback.</param>
+    /// <param name="selected">Selected directory path, or null.</param>
     private static void DispatchResult(SynchronizationContext? syncContext, Action<string?> onSelected, string? selected)
     {
         if (syncContext != null)
@@ -129,20 +181,32 @@ internal static class FolderDialogUtil
 
     #region Windows Implementation
 
+    // COM class ID of the shell's common file dialog (FileOpenDialog) and the interface IDs of IFileOpenDialog and
+    // IShellItem (shobjidl_core.h).
     private static readonly Guid CLSID_FileOpenDialog = new("DC1C5A9C-E88A-4DDE-A5A1-60F82A20AEF7");
     private static readonly Guid IID_IFileOpenDialog = new("d57c7288-d4ad-4768-be02-9d969532d960");
     private static readonly Guid IID_IShellItem = new("43826D1E-E718-42EE-BC55-A1E261C37BFE");
+    // HRESULT_FROM_WIN32(ERROR_CANCELLED) = 0x800704C7: IModalWindow::Show result when the user cancels the dialog.
+    // Reference: https://learn.microsoft.com/en-us/windows/win32/api/shobjidl_core/nf-shobjidl_core-imodalwindow-show
     private const int ERROR_CANCELLED_HR = unchecked((int)0x800704C7);
 
+    // Active window attached to the calling thread's message queue, or NULL.
     [DllImport("user32.dll")]
     private static extern IntPtr GetActiveWindow();
 
+    // Foreground window of the desktop (any process), or NULL.
     [DllImport("user32.dll")]
     private static extern IntPtr GetForegroundWindow();
 
+    // Thread ID that created the window; the process ID is returned through lpdwProcessId.
     [DllImport("user32.dll")]
     private static extern uint GetWindowThreadProcessId(IntPtr hWnd, out uint lpdwProcessId);
 
+    /// <summary>
+    /// Finds the game window to own the dialog, in order: the calling thread's active window, the foreground window when it
+    /// belongs to this process, then <see cref="Process.MainWindowHandle"/>.
+    /// </summary>
+    /// <returns>Window handle, or <see cref="IntPtr.Zero"/> when none is found or a call fails (the dialog is then unowned).</returns>
     private static IntPtr GetGameWindowHandle()
     {
         try
@@ -175,6 +239,13 @@ internal static class FolderDialogUtil
         return IntPtr.Zero;
     }
 
+    /// <summary>
+    /// Shows the IFileOpenDialog folder picker; when it throws (cannot be created, or Show fails with an error other than
+    /// cancel), logs a warning and shows the legacy SHBrowseForFolder dialog. Runs on the STA dialog thread.
+    /// </summary>
+    /// <param name="initialDirectory">Folder shown first, or empty.</param>
+    /// <param name="ownerHandle">Owner window, or <see cref="IntPtr.Zero"/>.</param>
+    /// <returns>Selected existing directory, or null on cancel.</returns>
     private static string? OpenWindowsFolderBrowser(string initialDirectory, IntPtr ownerHandle)
     {
         try
@@ -188,16 +259,31 @@ internal static class FolderDialogUtil
         }
     }
 
+    /// <summary>
+    /// Shows the shell common file dialog in folder mode.
+    /// <para>
+    /// Options: <c>FOS_PICKFOLDERS</c> (choose folders), <c>FOS_FORCEFILESYSTEM</c> (file system items only) and
+    /// <c>FOS_PATHMUSTEXIST</c>. The initial folder is set with <c>SetFolder</c> and <c>SetDefaultFolder</c> when it exists.
+    /// When <c>Show</c> fails with an owner window (error other than cancel), it is retried once without an owner.
+    /// The result item is read as a file system path (<c>SIGDN_FILESYSPATH</c>); the returned string is freed with
+    /// <see cref="Marshal.FreeCoTaskMem"/> and the COM objects are released.
+    /// </para>
+    /// </summary>
+    /// <param name="initialDirectory">Folder shown first, or empty.</param>
+    /// <param name="ownerHandle">Owner window, or <see cref="IntPtr.Zero"/>.</param>
+    /// <returns>Selected existing directory; null on cancel or when the result has no file system path.</returns>
+    /// <exception cref="COMException">The dialog cannot be created, or Show fails with an error other than cancel.</exception>
     private static string? OpenWindowsFolderBrowserModern(string initialDirectory, IntPtr ownerHandle)
     {
-        // 1. Try native CoCreateInstance first (works on Mono and .NET without class registration)
+        // 1. Create the dialog with ole32 CoCreateInstance (in-process server), marshalled directly to IFileOpenDialog.
         var clsid = CLSID_FileOpenDialog;
         var iid = IID_IFileOpenDialog;
         int createHr = CoCreateInstance(ref clsid, IntPtr.Zero, 1 /* CLSCTX_INPROC_SERVER */, ref iid, out var dialog);
 
         if (createHr != 0)
         {
-            // 2. Fallback to Activator via Type.GetTypeFromCLSID
+            // 2. On failure, create it through the runtime's COM interop (Type.GetTypeFromCLSID + Activator.CreateInstance).
+            //    createHr keeps the CoCreateInstance error for the exception below.
             var comType = Type.GetTypeFromCLSID(CLSID_FileOpenDialog);
             if (comType != null)
             {
@@ -223,6 +309,7 @@ internal static class FolderDialogUtil
                     var normalized = Path.GetFullPath(initialDirectory).TrimEnd('\\', '/');
                     if (Directory.Exists(normalized))
                     {
+                        // The dialog takes folders as IShellItem; SHCreateItemFromParsingName creates one from the path.
                         var shellItemGuid = IID_IShellItem;
                         int itemHr = SHCreateItemFromParsingName(normalized, IntPtr.Zero, ref shellItemGuid, out var initialItem);
                         if (itemHr == 0)
@@ -293,8 +380,19 @@ internal static class FolderDialogUtil
         }
     }
 
+    /// <summary>
+    /// Shows the legacy shell folder browser (<c>SHBrowseForFolderW</c>) with the resizable dialog style, an edit box, and
+    /// file system folders only. The initial folder is selected from the dialog callback (<c>BFFM_INITIALIZED</c> ->
+    /// <c>BFFM_SETSELECTIONW</c> with the path string). Cancel and failure both return null. Native buffers and the returned
+    /// item ID list are freed before returning.
+    /// </summary>
+    /// <param name="initialDirectory">Folder selected first, or empty.</param>
+    /// <param name="ownerHandle">Owner window, or <see cref="IntPtr.Zero"/>.</param>
+    /// <returns>Selected existing directory, or null.</returns>
     private static string? OpenWindowsFolderBrowserLegacy(string initialDirectory, IntPtr ownerHandle)
     {
+        // Display name buffer: MAX_PATH (260) UTF-16 characters, the size SHBrowseForFolder assumes.
+        // Reference: https://learn.microsoft.com/en-us/windows/win32/api/shlobj_core/ns-shlobj_core-browseinfow
         IntPtr pszDisplayName = Marshal.AllocHGlobal(260 * sizeof(char));
         IntPtr initialDirPtr = IntPtr.Zero;
         BrowseCallbackProc? callback = null;
@@ -318,6 +416,9 @@ internal static class FolderDialogUtil
                     var normalized = Path.GetFullPath(initialDirectory).TrimEnd('\\', '/');
                     if (Directory.Exists(normalized))
                     {
+                        // lpData = bi.lParam = the UTF-16 path; wParam 1 (TRUE) tells BFFM_SETSELECTION it is a string.
+                        // The delegate is kept alive until the dialog returns (GC.KeepAlive in finally).
+                        // Reference: https://learn.microsoft.com/en-us/previous-versions/windows/desktop/legacy/bb762598(v=vs.85)
                         initialDirPtr = Marshal.StringToHGlobalUni(normalized);
                         callback = (hwnd, uMsg, _, lpData) =>
                         {
@@ -340,12 +441,12 @@ internal static class FolderDialogUtil
             pidl = SHBrowseForFolderW(ref bi);
             if (pidl == IntPtr.Zero && ownerHandle != IntPtr.Zero)
             {
-                // If it returned null with ownerHandle, check if retry with IntPtr.Zero is appropriate
-                // But note: cancelling also returns Zero. We do not redundantly re-prompt if cancelled.
+                // SHBrowseForFolderW returns NULL both on cancel and on failure, so no retry without the owner is made.
             }
 
             if (pidl != IntPtr.Zero)
             {
+                // SHGetPathFromIDListW writes up to MAX_PATH (260) characters.
                 var sb = new StringBuilder(260);
                 if (SHGetPathFromIDListW(pidl, sb))
                 {
@@ -376,6 +477,10 @@ internal static class FolderDialogUtil
 
     #region COM & Win32 Interop Definitions
 
+    /// <summary>
+    /// <c>FILEOPENDIALOGOPTIONS</c> flags passed to <c>IFileDialog::SetOptions</c> (subset; values from shobjidl_core.h).
+    /// Reference: https://learn.microsoft.com/en-us/windows/win32/api/shobjidl_core/ne-shobjidl_core-_fileopendialogoptions
+    /// </summary>
     [Flags]
     private enum FOS : uint
     {
@@ -386,11 +491,20 @@ internal static class FolderDialogUtil
         FOS_FILEMUSTEXIST = 0x00001000,
     }
 
+    /// <summary>
+    /// Display name form requested from <c>IShellItem::GetDisplayName</c>; <c>SIGDN_FILESYSPATH</c> is the item's file system
+    /// path (the call fails for items without one).
+    /// Reference: https://learn.microsoft.com/en-us/windows/win32/api/shobjidl_core/ne-shobjidl_core-sigdn
+    /// </summary>
     private enum SIGDN : uint
     {
         SIGDN_FILESYSPATH = 0x80058000
     }
 
+    /// <summary>
+    /// COM interop declaration of the shell <c>IShellItem</c> interface (vtable order of shobjidl_core.h). Only
+    /// <c>GetDisplayName</c> is called; it keeps its HRESULT return (<c>PreserveSig</c>).
+    /// </summary>
     [ComImport]
     [Guid("43826D1E-E718-42EE-BC55-A1E261C37BFE")]
     [InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
@@ -404,6 +518,11 @@ internal static class FolderDialogUtil
         void Compare(IShellItem psi, uint hint, out int piOrder);
     }
 
+    /// <summary>
+    /// COM interop declaration of <c>IFileOpenDialog</c>: the methods of <c>IModalWindow</c> (<c>Show</c>), <c>IFileDialog</c>
+    /// and <c>IFileOpenDialog</c> in vtable order. <c>Show</c> keeps its HRESULT return (<c>PreserveSig</c>); the other methods
+    /// throw <see cref="COMException"/> on a failure HRESULT.
+    /// </summary>
     [ComImport]
     [Guid("d57c7288-d4ad-4768-be02-9d969532d960")]
     [InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
@@ -438,12 +557,15 @@ internal static class FolderDialogUtil
         void GetSelectedItems(out IntPtr ppsai);
     }
 
+    // Initializes COM as a single-threaded apartment plus OLE on the calling thread; returns an HRESULT (S_OK / S_FALSE on success).
     [DllImport("ole32.dll", ExactSpelling = true)]
     private static extern int OleInitialize(IntPtr pvReserved);
 
+    // Balances one successful OleInitialize on the same thread.
     [DllImport("ole32.dll", ExactSpelling = true)]
     private static extern void OleUninitialize();
 
+    // Creates a COM object of class rclsid and returns interface riid; declared here with the IFileOpenDialog return type.
     [DllImport("ole32.dll", ExactSpelling = true)]
     private static extern int CoCreateInstance(
         [In] ref Guid rclsid,
@@ -452,6 +574,7 @@ internal static class FolderDialogUtil
         [In] ref Guid riid,
         [Out, MarshalAs(UnmanagedType.Interface)] out IFileOpenDialog ppv);
 
+    // Creates an IShellItem from a parsing name (file system path); returns an HRESULT (0 = S_OK).
     [DllImport("shell32.dll", CharSet = CharSet.Unicode, PreserveSig = true)]
     private static extern int SHCreateItemFromParsingName(
         [MarshalAs(UnmanagedType.LPWStr)] string pszPath,
@@ -459,14 +582,22 @@ internal static class FolderDialogUtil
         [In] ref Guid riid,
         [Out, MarshalAs(UnmanagedType.Interface)] out IShellItem ppv);
 
+    // BROWSEINFO.ulFlags: file system directories only, resizable new-style dialog, edit box for typing a name.
+    // Reference: https://learn.microsoft.com/en-us/windows/win32/api/shlobj_core/ns-shlobj_core-browseinfow
     private const uint BIF_RETURNONLYFSDIRS = 0x0001;
     private const uint BIF_NEWDIALOGSTYLE = 0x0040;
     private const uint BIF_EDITBOX = 0x0010;
+    // Browse dialog messages (shlobj_core.h): BFFM_INITIALIZED is sent to the callback when the dialog has finished
+    // initializing; BFFM_SETSELECTIONW (WM_USER + 103, Unicode) is sent to the dialog to select a folder. The reference
+    // describes the messages; the numeric values are the shlobj_core.h definitions.
+    // Reference:https://learn.microsoft.com/en-us/previous-versions/windows/desktop/legacy/bb762598(v=vs.85)
     private const uint BFFM_INITIALIZED = 1;
     private const uint BFFM_SETSELECTIONW = 0x0400 + 103;
 
+    // BFFCALLBACK: called by the browse dialog for dialog events; returns 0 except for BFFM_VALIDATEFAILED.
     private delegate int BrowseCallbackProc(IntPtr hwnd, uint uMsg, IntPtr lParam, IntPtr lpData);
 
+    // Unicode BROWSEINFOW structure passed to SHBrowseForFolderW (field order and types of shlobj_core.h).
     [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
     private struct BROWSEINFO
     {
@@ -480,13 +611,16 @@ internal static class FolderDialogUtil
         public int iImage;
     }
 
+    // Shows the modal browse dialog; returns the selected item's ID list (freed with CoTaskMemFree), or NULL on cancel or failure.
     [DllImport("shell32.dll", CharSet = CharSet.Unicode)]
     private static extern IntPtr SHBrowseForFolderW(ref BROWSEINFO lpbi);
 
+    // Converts an item ID list to a file system path; false when the item is not part of the file system.
     [DllImport("shell32.dll", CharSet = CharSet.Unicode)]
     [return: MarshalAs(UnmanagedType.Bool)]
     private static extern bool SHGetPathFromIDListW(IntPtr pidl, StringBuilder pszPath);
 
+    // Sends a window message and waits for it to be processed (used from the browse dialog callback).
     [DllImport("user32.dll", CharSet = CharSet.Unicode)]
     private static extern IntPtr SendMessage(IntPtr hWnd, uint Msg, IntPtr wParam, IntPtr lParam);
 
@@ -496,10 +630,21 @@ internal static class FolderDialogUtil
 
     #region macOS Implementation
 
+    /// <summary>
+    /// Runs <c>osascript -e</c> with the AppleScript <c>POSIX path of (choose folder with prompt ... [default location ...])</c>
+    /// and blocks until the process exits. The initial directory is passed as a POSIX file in an AppleScript string literal
+    /// (backslashes and double quotes escaped). On cancel osascript prints nothing to standard output.
+    /// </summary>
+    /// <param name="initialDirectory">Folder shown first; used only when it is an existing directory.</param>
+    /// <returns>
+    /// The trimmed standard output when it is an existing directory; null on cancel, when the process cannot be started, or
+    /// on an exception (logged as a warning).
+    /// </returns>
     private static string? OpenMacFolderBrowser(string initialDirectory)
     {
         try
         {
+            // POSIX path of (...) converts the chosen folder alias to a slash-separated path.
             string script;
             if (!string.IsNullOrEmpty(initialDirectory) && Directory.Exists(initialDirectory))
             {
@@ -541,6 +686,17 @@ internal static class FolderDialogUtil
 
     #region Linux Implementation
 
+    /// <summary>
+    /// Runs <c>zenity --file-selection --directory --title=... [--filename=initialDirectory]</c> and blocks until it exits.
+    /// When zenity cannot be started, exits with a non-zero code (cancel or error) or prints a path that is not an existing
+    /// directory, runs <c>kdialog --getexistingdirectory [initialDirectory] --title ...</c> instead. Both commands print the
+    /// selected path to standard output.
+    /// </summary>
+    /// <param name="initialDirectory">Folder shown first; used only when it is an existing directory.</param>
+    /// <returns>
+    /// The selected existing directory; null when both dialogs return nothing, when kdialog cannot be started, or on an
+    /// exception (logged as a warning).
+    /// </returns>
     private static string? OpenLinuxFolderBrowser(string initialDirectory)
     {
         try

Util/OS/OSNotification.cs

@@ -13,26 +13,36 @@ namespace ADOFAIRenderer.Util.OS;
 ///   (WinRT <c>ToastNotificationManager</c>, script passed with <c>-EncodedCommand</c>).
 ///   With a folder path, the script also registers the <c>adofai-renderer://</c> URL protocol under
 ///   <c>HKCU\Software\Classes\adofai-renderer</c> (open command: <c>explorer.exe "&lt;folder&gt;"</c>)
-///   so the toast button opens the folder; the key is overwritten on each notification and stays registered.
+///   so the toast button opens the folder; the key is overwritten on each notification and stays registered, so every
+///   toast opens the folder of the most recent notification.
 ///   When PowerShell fails, a Win32 <c>Shell_NotifyIcon</c> balloon is shown via P/Invoke.
+///   Runs on a dedicated background thread ("OSNotification-Win").
 /// </para>
 /// <para>
-/// - <b>macOS</b>: Uses <c>osascript</c> with AppleScript's <c>display notification</c>.
+/// - <b>macOS</b>: Uses <c>osascript</c> with AppleScript's <c>display notification</c> (no folder action), started from the
+///   calling thread without waiting.
 /// </para>
 /// <para>
-/// - <b>Linux</b>: Uses <c>notify-send</c> (libnotify) with <c>xdg-open</c> for folder actions.
+/// - <b>Linux</b>: Uses <c>notify-send</c> (libnotify) and, when it cannot be started, <c>gdbus</c> calling
+///   <c>org.freedesktop.Notifications.Notify</c>. With a folder path, <c>notify-send --action</c> runs on a thread pool task
+///   and <c>xdg-open</c> opens the folder when the action is chosen.
 /// </para>
+/// <para>Other platforms: nothing is shown. Failures are logged as warnings; no exception reaches the caller.</para>
 /// </summary>
 internal static class OSNotification
 {
     /// <summary>
-    /// Sends a native desktop notification.
-    /// If <paramref name="folderPath"/> is provided, Windows and Linux will attempt to open
-    /// the folder when the notification is clicked/dismissed.
+    /// Sends a native desktop notification and returns without waiting for it to be shown (see the class summary for the
+    /// thread used on each platform).
+    /// If <paramref name="folderPath"/> is provided, Windows and Linux offer to open the folder from the notification.
+    /// Exceptions thrown while starting the platform implementation are caught and logged as warnings.
     /// </summary>
     /// <param name="title">The notification title.</param>
     /// <param name="message">The notification body text.</param>
-    /// <param name="folderPath">Optional folder path to open on click (Windows balloon click / Linux action).</param>
+    /// <param name="folderPath">
+    /// Optional folder path to open from the notification (Windows toast click or button / Windows balloon click / Linux action);
+    /// ignored on macOS.
+    /// </param>
     public static void Show(string title, string message, string? folderPath = null)
     {
         try
@@ -65,6 +75,13 @@ internal static class OSNotification
     /// </summary>
     private static class WindowsNotification
     {
+        /// <summary>
+        /// Starts a background thread ("OSNotification-Win") that tries the toast and shows the balloon when the toast fails.
+        /// Returns immediately. Exceptions on the thread are caught and logged.
+        /// </summary>
+        /// <param name="title">Notification title.</param>
+        /// <param name="message">Notification body text.</param>
+        /// <param name="folderPath">Folder to open from the notification, or null.</param>
         public static void Send(string title, string message, string? folderPath)
         {
             var thread = new Thread(() =>
@@ -95,11 +112,23 @@ internal static class OSNotification
         /// With a folder path, registers the adofai-renderer:// protocol in HKCU first (see class summary).
         /// Waits up to 5 seconds for the process. Returns true when it exits with code 0,
         /// false when it exits with another code, does not exit within 5 seconds, or fails to start.
+        /// <para>
+        /// The toast XML uses the <c>ToastGeneric</c> template with the title and message as two text elements; with a folder
+        /// path it also sets <c>launch</c> and an "Open Render Folder" action to the <c>adofai-renderer://</c> URI with protocol
+        /// activation. The notifier is created with the application ID "ADOFAI Renderer". The script is passed as Base64 of its
+        /// UTF-16LE bytes (<c>-EncodedCommand</c>), so no command line quoting is needed.
+        /// </para>
         /// </summary>
+        /// <param name="title">Notification title (XML-escaped into the toast).</param>
+        /// <param name="message">Notification body text (XML-escaped into the toast).</param>
+        /// <param name="folderPath">Folder opened by the protocol handler, or null for a toast without action.</param>
+        /// <returns>True when PowerShell exited with code 0 within 5 seconds; false otherwise (the stderr text or exception is logged).</returns>
         private static bool TrySendToast(string title, string message, string? folderPath)
         {
             try
             {
+                // SecurityElement.Escape replaces < > & " ' with XML entities, so the text also cannot end the
+                // single-quoted PowerShell string that holds the XML.
                 string xmlTitle = System.Security.SecurityElement.Escape(title) ?? title;
                 string xmlMessage = System.Security.SecurityElement.Escape(message) ?? message;
 
@@ -108,8 +137,13 @@ internal static class OSNotification
 
                 if (!string.IsNullOrEmpty(folderPath))
                 {
+                    // A single quote is written as two single quotes inside a single-quoted PowerShell string.
                     var escapedFolder = folderPath.Replace("'", "''");
 
+                    // Script: register HKCU\Software\Classes\adofai-renderer as a URL protocol ("URL Protocol" value, default
+                    // value "URL:adofai-renderer Protocol") whose shell\open\command runs explorer.exe on the folder, then load
+                    // the WinRT types and show the toast.
+
                     toastXml =
                         "<toast launch=\"adofai-renderer://\" activationType=\"protocol\">" +
                         "<visual><binding template=\"ToastGeneric\">" +
@@ -148,6 +182,7 @@ internal static class OSNotification
                         "[Windows.UI.Notifications.ToastNotificationManager]::CreateToastNotifier('ADOFAI Renderer').Show([Windows.UI.Notifications.ToastNotification]::new($xml))";
                 }
 
+                // -EncodedCommand takes Base64 of the UTF-16LE script text.
                 byte[] bytes = System.Text.Encoding.Unicode.GetBytes(psScript);
                 string base64 = Convert.ToBase64String(bytes);
 
@@ -166,7 +201,8 @@ internal static class OSNotification
                 process.Start();
                 process.WaitForExit(5000);
 
-                // If PowerShell exited with error, treat as failure
+                // ExitCode throws InvalidOperationException while the process is still running (timeout), which the catch
+                // below reports as a failure. If PowerShell exited with error, treat as failure
                 if (process.ExitCode != 0)
                 {
                     string stderr = process.StandardError.ReadToEnd().Trim();
@@ -189,9 +225,14 @@ internal static class OSNotification
         #region Balloon via Shell_NotifyIcon
 
         // ReSharper disable InconsistentNaming
+        // Shell_NotifyIcon messages: add / delete the notification area icon.
+        // Reference: https://learn.microsoft.com/en-us/windows/win32/api/shellapi/nf-shellapi-shell_notifyiconw
         private const int NIM_ADD = 0x00;
         private const int NIM_DELETE = 0x02;
 
+        // NOTIFYICONDATAW.uFlags: uCallbackMessage, hIcon, szTip and the balloon fields (szInfo, szInfoTitle, dwInfoFlags)
+        // are valid. NIIF_INFO: information icon in the balloon.
+        // Reference: https://learn.microsoft.com/en-us/windows/win32/api/shellapi/ns-shellapi-notifyicondataw
         private const int NIF_MESSAGE = 0x01;
         private const int NIF_ICON = 0x02;
         private const int NIF_TIP = 0x04;
@@ -199,18 +240,25 @@ internal static class OSNotification
 
         private const int NIIF_INFO = 0x01;
 
+        // WM_USER (winuser.h) starts the private window message range; WM_TRAYICON is the application-defined callback
+        // message of the icon. NIN_BALLOONUSERCLICK (shellapi.h, WM_USER + 5) arrives as lParam of the callback message when
+        // the user clicks the balloon.
         private const int WM_USER = 0x0400;
         private const int WM_TRAYICON = WM_USER + 1;
         private const int NIN_BALLOONUSERCLICK = 0x0405;
 
+        // Window style of the hidden message window (winuser.h), WM_CLOSE message ID (winuser.h), and the application-defined
+        // icon ID (any value unique for the window).
         private const int WS_OVERLAPPED = 0x00000000;
         private const uint WM_CLOSE = 0x0010;
         private const int TRAY_ICON_UID = 29471;
         // ReSharper restore InconsistentNaming
 
+        // Adds, modifies or deletes a notification area icon; returns false on failure.
         [DllImport("shell32.dll", CharSet = CharSet.Unicode)]
         private static extern bool Shell_NotifyIconW(int dwMessage, ref NotifyIconDataW lpData);
 
+        // Creates the window that owns the icon and receives its callback messages; returns NULL on failure.
         [DllImport("user32.dll", CharSet = CharSet.Unicode)]
         private static extern IntPtr CreateWindowExW(
             int dwExStyle, string lpClassName, string lpWindowName,
@@ -221,9 +269,12 @@ internal static class OSNotification
         [return: MarshalAs(UnmanagedType.Bool)]
         private static extern bool DestroyWindow(IntPtr hWnd);
 
+        // Loads a predefined system icon when hInstance is NULL.
+        // Reference: https://learn.microsoft.com/en-us/windows/win32/api/winuser/nf-winuser-loadiconw
         [DllImport("user32.dll")]
         private static extern IntPtr LoadIconW(IntPtr hInstance, IntPtr lpIconName);
 
+        // Message loop functions of the calling thread: GetMessageW blocks until a message arrives and returns false for WM_QUIT.
         [DllImport("user32.dll")]
         [return: MarshalAs(UnmanagedType.Bool)]
         private static extern bool GetMessageW(out Msg lpMsg, IntPtr hWnd, uint wMsgFilterMin, uint wMsgFilterMax);
@@ -234,10 +285,13 @@ internal static class OSNotification
         [DllImport("user32.dll")]
         private static extern IntPtr DispatchMessageW(ref Msg lpMsg);
 
+        // Places a message in the window's thread queue and returns without waiting (callable from any thread).
         [DllImport("user32.dll")]
         [return: MarshalAs(UnmanagedType.Bool)]
         private static extern bool PostMessageW(IntPtr hWnd, uint msg, IntPtr wParam, IntPtr lParam);
 
+        // NOTIFYICONDATAW up to dwInfoFlags (without guidItem and hBalloonIcon); cbSize is the size of this layout.
+        // String fields hold at most SizeConst characters including the terminating null.
         [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
         private struct NotifyIconDataW
         {
@@ -259,6 +313,7 @@ internal static class OSNotification
             public int dwInfoFlags;
         }
 
+        // Win32 MSG structure filled by GetMessageW.
         [StructLayout(LayoutKind.Sequential)]
         private struct Msg
         {
@@ -271,8 +326,22 @@ internal static class OSNotification
             public int pt_y;
         }
 
+        /// <summary>
+        /// Shows a notification area balloon through <c>Shell_NotifyIconW</c>, owned by a hidden message-only window.
+        /// <para>
+        /// Without a folder path the icon stays for 500 ms and is then removed. With a folder path the method runs a message
+        /// loop on the calling thread for up to 12 seconds (a timer posts <c>WM_CLOSE</c>); a balloon click
+        /// (<c>NIN_BALLOONUSERCLICK</c>) opens the folder through the shell (<c>UseShellExecute</c>) and ends the loop.
+        /// The icon is deleted and the window destroyed before returning. Errors are logged as warnings.
+        /// </para>
+        /// </summary>
+        /// <param name="title">Balloon title; truncated to 63 characters.</param>
+        /// <param name="message">Balloon text; truncated to 255 characters.</param>
+        /// <param name="folderPath">Folder opened on balloon click, or null.</param>
         private static void SendBalloon(string title, string message, string? folderPath)
         {
+            // szInfoTitle holds 64 and szInfo 256 characters including the terminating null.
+            // Reference: https://learn.microsoft.com/en-us/windows/win32/api/shellapi/ns-shellapi-notifyicondataw
             if (title.Length > 63) title = title.Substring(0, 63);
             if (message.Length > 255) message = message.Substring(0, 255);
 
@@ -281,6 +350,7 @@ internal static class OSNotification
 
             try
             {
+                // HWND_MESSAGE ((HWND)-3, winuser.h) as parent creates a message-only window of the "Static" class.
                 var hwndMessage = new IntPtr(-3);
                 hWnd = CreateWindowExW(
                     0, "Static", "ADOFAIRendererNotify",
@@ -293,6 +363,7 @@ internal static class OSNotification
                     return;
                 }
 
+                // 32512 = IDI_APPLICATION (winuser.h), the default application icon.
                 IntPtr hIcon = LoadIconW(IntPtr.Zero, (IntPtr)32512);
 
                 nid.cbSize = Marshal.SizeOf(typeof(NotifyIconDataW));
@@ -305,6 +376,7 @@ internal static class OSNotification
                 nid.szInfo = message;
                 nid.szInfoTitle = title;
                 nid.dwInfoFlags = NIIF_INFO;
+                // uTimeout in milliseconds; deprecated as of Windows Vista (display time follows the system settings).
                 nid.uTimeoutOrVersion = 4;
 
                 Shell_NotifyIconW(NIM_ADD, ref nid);
@@ -327,6 +399,7 @@ internal static class OSNotification
 
                             if (msg.message == WM_TRAYICON)
                             {
+                                // No NIM_SETVERSION call: lParam carries the notification event (NIN_*) directly.
                                 int notifyMsg = (int)(long)msg.lParam;
                                 if (notifyMsg == NIN_BALLOONUSERCLICK)
                                 {
@@ -388,6 +461,12 @@ internal static class OSNotification
     /// </summary>
     private static class MacNotification
     {
+        /// <summary>
+        /// Starts <c>osascript -e "display notification ... with title ..."</c> without waiting. Exceptions from starting the
+        /// process (for example osascript missing) propagate to <see cref="OSNotification.Show"/>.
+        /// </summary>
+        /// <param name="title">Notification title.</param>
+        /// <param name="message">Notification body text.</param>
         public static void Send(string title, string message)
         {
             // AppleScript string escaping: backslash and double-quote
@@ -412,6 +491,9 @@ internal static class OSNotification
             RunProcess(startInfo);
         }
 
+        /// <summary>Escapes a value for use inside a double-quoted AppleScript string literal.</summary>
+        /// <param name="value">Raw text.</param>
+        /// <returns>The text with each backslash and double quote preceded by a backslash.</returns>
         private static string EscapeAppleScript(string value)
         {
             // In AppleScript string literals, escape backslash and double-quote
@@ -431,6 +513,13 @@ internal static class OSNotification
     /// </summary>
     private static class LinuxNotification
     {
+        /// <summary>
+        /// Shows the notification with an "Open Render Folder" action when <paramref name="folderPath"/> is set (thread pool
+        /// task), otherwise a plain notification started from the calling thread.
+        /// </summary>
+        /// <param name="title">Notification summary.</param>
+        /// <param name="message">Notification body.</param>
+        /// <param name="folderPath">Folder opened by the action, or null.</param>
         public static void Send(string title, string message, string? folderPath)
         {
             if (!string.IsNullOrEmpty(folderPath))
@@ -443,6 +532,9 @@ internal static class OSNotification
             }
         }
 
+        /// <summary>Starts notify-send; when it cannot be started, starts gdbus. Neither process is waited for.</summary>
+        /// <param name="title">Notification summary.</param>
+        /// <param name="message">Notification body.</param>
         private static void ShowSimple(string title, string message)
         {
             // Try notify-send first
@@ -453,6 +545,15 @@ internal static class OSNotification
             TryGdbus(title, message);
         }
 
+        /// <summary>
+        /// On a thread pool task, runs <c>notify-send -a "ADOFAI Renderer" --action=open_folder=Open Render Folder</c> and waits
+        /// for it to exit. notify-send prints the key of the chosen action ("open_folder") to standard output; in that case
+        /// <c>xdg-open &lt;folderPath&gt;</c> is started. When an exception occurs (for example notify-send missing), it is logged
+        /// and <see cref="ShowSimple"/> shows the notification without the action.
+        /// </summary>
+        /// <param name="title">Notification summary.</param>
+        /// <param name="message">Notification body.</param>
+        /// <param name="folderPath">Folder passed to xdg-open.</param>
         private static void ShowWithAction(string title, string message, string folderPath)
         {
             // Run on a background thread because notify-send with --action blocks
@@ -505,6 +606,10 @@ internal static class OSNotification
             });
         }
 
+        /// <summary>Starts <c>notify-send -a "ADOFAI Renderer" &lt;title&gt; &lt;message&gt;</c> without waiting.</summary>
+        /// <param name="title">Notification summary.</param>
+        /// <param name="message">Notification body.</param>
+        /// <returns>True when the process was started (its exit code is not checked); false when starting it threw.</returns>
         private static bool TryNotifySend(string title, string message)
         {
             try
@@ -530,6 +635,13 @@ internal static class OSNotification
             }
         }
 
+        /// <summary>
+        /// Starts <c>gdbus call --session</c> to <c>org.freedesktop.Notifications.Notify</c> (arguments app_name, replaces_id,
+        /// app_icon, summary, body, actions, hints, expire_timeout) without waiting. Start failures are logged as warnings.
+        /// Reference: https://specifications.freedesktop.org/notification/latest/protocol.html
+        /// </summary>
+        /// <param name="title">Notification summary.</param>
+        /// <param name="message">Notification body.</param>
         private static void TryGdbus(string title, string message)
         {
             try

Util/OS/RegistryUtil.cs

@@ -2,16 +2,37 @@ using System;
 
 namespace ADOFAIRenderer.Util.OS;
 
+/// <summary>
+/// Read-only access to <c>HKEY_LOCAL_MACHINE</c> (64-bit registry view) through reflection.
+/// <para>
+/// The mod targets netstandard2.1, which does not expose <c>Microsoft.Win32.RegistryKey</c>; the game runtime (Mono)
+/// provides it in its core library. The types and methods are looked up once in the static constructor and invoked through
+/// reflection.
+/// </para>
+/// <para>
+/// Intended for Windows. On other platforms the result depends on the runtime's registry support; when the types or methods
+/// are not found, or a call throws, every method returns null.
+/// All failures (missing key, access denied, reflection errors) are caught and reported as null; nothing is logged.
+/// Stateless and safe to call from any thread; each call opens and closes its own keys.
+/// </para>
+/// </summary>
 internal static class RegistryUtil
 {
+    // Reflected Microsoft.Win32 types; null when the runtime does not provide them.
     private static readonly Type? RegistryKeyType;
     private static readonly Type? RegistryHiveType;
     private static readonly Type? RegistryViewType;
+    // RegistryKey.OpenBaseKey(RegistryHive, RegistryView) (static), OpenSubKey(string) (read-only open),
+    // GetSubKeyNames() and GetValue(string).
     private static readonly System.Reflection.MethodInfo? OpenBaseKeyMethod;
     private static readonly System.Reflection.MethodInfo? OpenSubKeyMethod;
     private static readonly System.Reflection.MethodInfo? GetSubKeyNamesMethod;
     private static readonly System.Reflection.MethodInfo? GetValueMethod;
 
+    /// <summary>
+    /// Resolves the registry types by name (<see cref="Type.GetType(string)"/>, then the core library that defines
+    /// <see cref="object"/>) and their methods. Leaves the fields null on any failure.
+    /// </summary>
     static RegistryUtil()
     {
         try
@@ -42,6 +63,8 @@ internal static class RegistryUtil
         }
     }
 
+    /// <summary>Closes a reflected RegistryKey (Dispose, or Close when it is not IDisposable). Ignores null and errors.</summary>
+    /// <param name="key">RegistryKey instance returned by a reflected call, or null.</param>
     private static void CloseKey(object? key)
     {
         if (key == null || RegistryKeyType == null) return;
@@ -63,6 +86,11 @@ internal static class RegistryUtil
         }
     }
 
+    /// <summary>
+    /// Returns the names of the direct subkeys of <c>HKEY_LOCAL_MACHINE\&lt;parentKeyPath&gt;</c> in the 64-bit registry view.
+    /// </summary>
+    /// <param name="parentKeyPath">Key path relative to HKEY_LOCAL_MACHINE, with backslash separators.</param>
+    /// <returns>Subkey names, or null when the key does not exist, cannot be opened, or the registry is unavailable.</returns>
     // ReSharper disable once InconsistentNaming
     public static string[]? GetHKLMSubKeyNames(string parentKeyPath)
     {
@@ -71,6 +99,10 @@ internal static class RegistryUtil
 
         try
         {
+            // RegistryHive.LocalMachine = 0x80000002 (-2147483646), RegistryView.Registry64 = 256.
+            // On a 32-bit OS a Registry64 request returns the 32-bit view.
+            // Reference: https://learn.microsoft.com/en-us/dotnet/api/microsoft.win32.registryhive
+            // Reference: https://learn.microsoft.com/en-us/dotnet/api/microsoft.win32.registryview
             object hiveLocalMachine = Enum.ToObject(RegistryHiveType!, 0x80000002);
             object viewRegistry64 = Enum.ToObject(RegistryViewType!, 256);
 
@@ -95,6 +127,15 @@ internal static class RegistryUtil
         }
     }
 
+    /// <summary>
+    /// Reads a string value of <c>HKEY_LOCAL_MACHINE\&lt;keyPath&gt;</c> in the 64-bit registry view.
+    /// </summary>
+    /// <param name="keyPath">Key path relative to HKEY_LOCAL_MACHINE, with backslash separators.</param>
+    /// <param name="valueName">Value name; an empty string reads the key's default value.</param>
+    /// <returns>
+    /// The value when it exists and is a string (REG_SZ / REG_EXPAND_SZ); null when the key or value does not exist, the value
+    /// has another type, or the registry is unavailable.
+    /// </returns>
     // ReSharper disable once InconsistentNaming
     public static string? GetHKLMValue(string keyPath, string valueName)
     {
@@ -103,6 +144,7 @@ internal static class RegistryUtil
 
         try
         {
+            // Same hive and view constants as GetHKLMSubKeyNames.
             object hiveLocalMachine = Enum.ToObject(RegistryHiveType!, 0x80000002);
             object viewRegistry64 = Enum.ToObject(RegistryViewType!, 256);
 

Util/ParticleUtil.cs

@@ -4,10 +4,22 @@ using UnityEngine;
 
 namespace ADOFAIRenderer.Util
 {
+    /// <summary>Particle system helpers.</summary>
     internal static class ParticleUtil
     {
+        /// <summary>
+        /// Renderer found for each particle system. Weak keys: an entry is dropped when its ParticleSystem object is collected.
+        /// Main thread.
+        /// </summary>
         private static readonly ConditionalWeakTable<ParticleSystem, ParticleSystemRenderer> Cache = new();
 
+        /// <summary>
+        /// Returns the ParticleSystemRenderer that belongs to <paramref name="ps"/>. When a GameObject has several particle
+        /// systems and renderers, the renderer with the same component index as the particle system is used; otherwise the
+        /// first renderer of the GameObject. The result is cached per particle system. Main thread.
+        /// </summary>
+        /// <param name="ps">Particle system; null or destroyed returns null.</param>
+        /// <returns>The renderer, or null when the GameObject has none.</returns>
         public static ParticleSystemRenderer? GetRenderer(this ParticleSystem ps)
         {
             if (!ps) return null;

Util/RationalUtil.cs

@@ -2,8 +2,19 @@ using System;
 
 namespace ADOFAIRenderer.Util
 {
+    /// <summary>Conversion of floating-point rates (frame rates) to integer fractions.</summary>
     internal static class RationalUtil
     {
+        /// <summary>
+        /// Best rational approximation Numerator / Denominator of <paramref name="value"/> by continued fraction expansion:
+        /// the last convergent whose numerator fits in int and whose denominator does not exceed
+        /// <paramref name="maxDenominator"/>. Exact for values with a short expansion (for example 60 gives 60/1). The sign is
+        /// carried by the numerator; 0 gives 0/1. A magnitude above int.MaxValue has no valid convergent and gives 1/0.
+        /// Thread-safe (pure function).
+        /// </summary>
+        /// <param name="value">Value to convert, for example a frame rate in frames per second.</param>
+        /// <param name="maxDenominator">Largest allowed denominator (default 100000000).</param>
+        /// <returns>Numerator and denominator (positive for magnitudes up to int.MaxValue).</returns>
         public static (int Numerator, int Denominator) Double2MaxPrecisionInt(double value,
             int maxDenominator = 100000000)
         {

Util/VideoBGPlayer.cs

@@ -9,9 +9,25 @@ using FFmpeg.AutoGen;
 
 namespace ADOFAIRenderer.Util;
 
+/// <summary>
+/// Plays a custom level's background video with FFmpeg (FFmpegNativeDecoder) in place of Unity's VideoPlayer while a
+/// render is active, so the video frame shown always matches the render clock. Attached to the scnGame.videoBG object
+/// by scnGamePatch.ReplaceVideo, which disables the native VideoPlayer; removed again by that patch when no render is
+/// active.
+/// <para>
+/// Every LateUpdate it computes the video time from the conductor (the same formula scrVfxPlus uses to start and
+/// position the native video), decodes frames up to that time and draws the newest one either into the VideoPlayer's
+/// target RenderTexture or onto a quad at the far plane of the background camera.
+/// Decoded YUV frames are converted to RGBA on the GPU (ColorConversion.compute, kernels CSMain_NV12ToRGBA /
+/// CSMain_YUV420PToRGBA); other pixel formats, or a missing shader, use the decoder's RGBA output (CPU conversion).
+/// Main thread only.
+/// </para>
+/// </summary>
 // ReSharper disable once InconsistentNaming
 internal class VideoBGPlayer : MonoBehaviour
 {
+    // Property IDs of the compute shader parameters: input planes, output texture, frame size in pixels,
+    // ColorRange (1 = full range, 0 = limited range) and ColorMatrix (FFmpegNativeDecoder.ColorMatrix).
     private static readonly int YTex = Shader.PropertyToID("_YTex");
     private static readonly int UVTex = Shader.PropertyToID("_UVTex");
     private static readonly int Result = Shader.PropertyToID("_Result");
@@ -22,6 +38,10 @@ internal class VideoBGPlayer : MonoBehaviour
     private static readonly int ColorRange = Shader.PropertyToID("ColorRange");
     private static readonly int ColorMatrix = Shader.PropertyToID("ColorMatrix");
 
+    /// <summary>
+    /// Conversion path of the current video: <c>None</c> = CPU RGBA texture, <c>YUV420P</c> = separate Y, U, V planes,
+    /// <c>NV12</c> = Y plane and interleaved UV plane.
+    /// </summary>
     [SuppressMessage("ReSharper", "InconsistentNaming")]
     private enum GPUMode
     {
@@ -30,6 +50,7 @@ internal class VideoBGPlayer : MonoBehaviour
         NV12
     }
 
+    /// <summary>Decoder of the current video; null when not initialized or after CleanUp.</summary>
     private FFmpegNativeDecoder? _decoder;
         
     // CPU fallback rendering
@@ -47,16 +68,34 @@ internal class VideoBGPlayer : MonoBehaviour
     private RenderTexture? _renderTexture;
     private int _kernelIndex = -1;
 
+    /// <summary>Presentation time in seconds of the frame currently shown (video time, 0 = start of the file).</summary>
     private double _currentFrameTimestamp;
+    /// <summary>Video time in seconds from which the next frame is decoded (current timestamp + 1 / FPS).</summary>
     private double _nextFrameTimestamp;
+    /// <summary>Conversion path selected by Init.</summary>
     private GPUMode _gpuMode = GPUMode.None;
+    /// <summary>Target RenderTexture of the native VideoPlayer; null when the video is shown on the background quad.</summary>
     private RenderTexture? _targetTexture;
+    /// <summary>Whether the level loops the video (miscSettings "loopVideo").</summary>
     private bool _isLooping;
+    /// <summary>True after a successful Init; set to false by CleanUp or a playback error (playback then stops).</summary>
     private bool _isInitialized;
 
+    /// <summary>Background quad created by SetupBackgroundQuad when there is no target texture; hidden until the first frame.</summary>
     private GameObject? _quad;
+    /// <summary>Material of the background quad; its main texture is the converted frame.</summary>
     private Material? _material;
 
+    /// <summary>
+    /// Releases any previous video and opens <paramref name="videoPath"/>. Allocates the plane textures for the GPU path
+    /// of the decoder's pixel format (chroma planes are (width + 1) / 2 x (height + 1) / 2), or an RGBA texture for the
+    /// CPU path. Errors are logged; the player then stays uninitialized and shows nothing.
+    /// </summary>
+    /// <param name="videoPath">Full path of the video file.</param>
+    /// <param name="targetTexture">RenderTexture the native VideoPlayer renders into, or null to draw on a background quad.</param>
+    /// <param name="loop">Whether the video loops.</param>
+    /// <param name="targetCamera">Camera the background quad is attached to when <paramref name="targetTexture"/> is null.</param>
+    /// <param name="videoBGGo">VideoPlayer object; its layer is given to the background quad.</param>
     // ReSharper disable once InconsistentNaming
     public void Init(string videoPath, RenderTexture? targetTexture, bool loop, Camera? targetCamera, GameObject videoBGGo)
     {
@@ -169,12 +208,19 @@ internal class VideoBGPlayer : MonoBehaviour
         }
     }
 
+    /// <summary>Sets clamp wrapping and bilinear filtering.</summary>
     private static void ConfigureTexture(Texture2D tex)
     {
         tex.wrapMode = TextureWrapMode.Clamp;
         tex.filterMode = FilterMode.Bilinear;
     }
 
+    /// <summary>
+    /// Main thread, every frame after the song has started. Computes the video time, seeks when it moved backwards or more
+    /// than 1 s ahead of the shown frame, decodes frames until the next frame lies after that time, and draws the last
+    /// decoded frame. Before the video starts (negative time) the target texture is cleared to black and the quad hidden.
+    /// When decoding fails at the end of the file, a looping video seeks to 0; otherwise the last frame stays.
+    /// </summary>
     private void LateUpdate()
     {
         if (!_isInitialized || _decoder == null) return;
@@ -182,6 +228,9 @@ internal class VideoBGPlayer : MonoBehaviour
         var cond = scrConductor.instance;
         if (!cond || !cond.hasSongStarted) return;
             
+        // Song position in seconds of song time, as scrConductor computes songposition_minusi from dspTime with the input
+        // offset calibration_i = 0 (the render sets the input offset to 0), minus the separate countdown length.
+        // scrVfxPlus starts the native video at songposition_minusi - countdown + vidOffset (scrVfxPlus.cs).
         var pitch = cond.song.pitch;
         var separateCountdownOffset = cond.separateCountdownTime ? 
             cond.crotchetAtStart * cond.adjustedCountdownTicks : 0.0;
@@ -215,6 +264,7 @@ internal class VideoBGPlayer : MonoBehaviour
         }
 
 
+        // scrVfxPlus hides the tutorial (editor) background when the native video starts (scrVfxPlus.cs).
         if (ADOBase.customLevel)
         {
             ADOBase.customLevel.ShowTutorialBackground(false);
@@ -222,6 +272,7 @@ internal class VideoBGPlayer : MonoBehaviour
 
         try
         {
+            // A seek is cheaper than decoding many frames when the time jumped forward by more than 1 s.
             if (targetVideoTime < _currentFrameTimestamp || targetVideoTime - _currentFrameTimestamp > 1.0)
             {
                 _decoder.SeekToTime(targetVideoTime);
@@ -298,6 +349,10 @@ internal class VideoBGPlayer : MonoBehaviour
         }
     }
 
+    /// <summary>
+    /// Uploads the decoded planes, converts them to RGBA with the compute shader (or uploads the RGBA texture), and shows
+    /// the result: blitted into the target texture, or set as the quad's main texture (the quad is activated).
+    /// </summary>
     private void RenderToTarget()
     {
         if (_decoder == null) return;
@@ -318,6 +373,7 @@ internal class VideoBGPlayer : MonoBehaviour
             _computeShader.SetInt(ColorRange, _decoder.ColorRange == AVColorRange.AVCOL_RANGE_JPEG ? 1 : 0);
             _computeShader.SetInt(ColorMatrix, _decoder.ColorMatrix);
 
+            // One thread group per 8 x 8 output pixels, rounded up (group size expected by the ColorConversion.compute kernels).
             int threadGroupsX = (w + 7) / 8;
             int threadGroupsY = (h + 7) / 8;
             _computeShader.Dispatch(_kernelIndex, threadGroupsX, threadGroupsY, 1);
@@ -353,6 +409,7 @@ internal class VideoBGPlayer : MonoBehaviour
             _computeShader.SetInt(ColorRange, _decoder.ColorRange == AVColorRange.AVCOL_RANGE_JPEG ? 1 : 0);
             _computeShader.SetInt(ColorMatrix, _decoder.ColorMatrix);
 
+            // One thread group per 8 x 8 output pixels, rounded up (group size expected by the ColorConversion.compute kernels).
             int threadGroupsX = (w + 7) / 8;
             int threadGroupsY = (h + 7) / 8;
             _computeShader.Dispatch(_kernelIndex, threadGroupsX, threadGroupsY, 1);
@@ -394,11 +451,16 @@ internal class VideoBGPlayer : MonoBehaviour
         }
     }
 
+    /// <summary>Releases the decoder and GPU resources when the component is destroyed.</summary>
     private void OnDestroy()
     {
         CleanUp();
     }
 
+    /// <summary>
+    /// Disposes the decoder and destroys the textures, the RenderTexture, the background quad and its material.
+    /// The player is uninitialized afterwards. Called by Init, on errors and on destroy.
+    /// </summary>
     public void CleanUp()
     {
         _isInitialized = false;
@@ -446,6 +508,12 @@ internal class VideoBGPlayer : MonoBehaviour
         }
     }
 
+    /// <summary>
+    /// Creates a quad as a child of <paramref name="targetCamera"/>, 0.5 units in front of its far clip plane, scaled to
+    /// fill the view (orthographic size or field of view), on the layer of <paramref name="videoBGGo"/>. Its shader is
+    /// taken from scrCamera's camera quad material when available, otherwise the first of Sprites/Default, Unlit/Texture
+    /// and Standard that exists. The quad starts inactive.
+    /// </summary>
     // ReSharper disable once InconsistentNaming
     private void SetupBackgroundQuad(Camera targetCamera, GameObject videoBGGo)
     {