Document Render Core And API

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 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 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;
@@ -74,11 +123,34 @@ 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>
@@ -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 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 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 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 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;
+
+    /// <summary>
+    /// Video frame index of the last capture request (-1 before the first). Written on the main 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 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 thread had to wait for the render thread (throttle loop entries).</summary>
     public int throttleCount;
+
+    /// <summary>True while the main 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 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)
     {
@@ -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 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