Switch Render Audio To Voice Mixer

Core/RenderManager.cs

@@ -146,6 +146,9 @@ internal class RenderManager : MonoBehaviour
     public int frameCountBase;
         
     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;
     private AudioSyncCalculator? SyncCalculator { get; set; }
 
     private FrameReader? _frameReader;
@@ -412,7 +415,16 @@ internal class RenderManager : MonoBehaviour
     // ReSharper disable once Unity.IncorrectMethodSignature
     public void OnPostFrame(RenderTexture? texture)
     {
-        if (Instance.stage < RenderStage.Render || !texture) return;
+        if (Instance.stage < RenderStage.Render) return;
+
+        // Audio commands of this frame are queued: update the song voice and let the render thread mix up to the next frame.
+        if (AudioMixer != null)
+        {
+            AudioMixer.UpdateBGM(AudioTime, dspTimeBase);
+            AudioMixer.Commit((frameCount + 1) / Configuration.RenderFPS);
+        }
+
+        if (!texture) return;
 
         // [Backpressure Throttling]
         isThrottling = false;
@@ -682,7 +694,7 @@ internal class RenderManager : MonoBehaviour
             throw;
         }
 
-        var encoder = videoFFmpeg!;
+        var encoder = videoFFmpeg;
         RenderThread = new Thread(() => RunRenderThread(encoder))
         {
             IsBackground = true,
@@ -816,17 +828,13 @@ internal class RenderManager : MonoBehaviour
     {
         if (!Configuration.AudioConfig.RenderAudio || SyncCalculator is not { } syncCalculator) return;
 
-        var frameIdx = (int)(passCount - 1);
-        var effectiveVideoFps = Math.Min(Configuration.VideoFPS, Configuration.RenderFPS);
-        var frameTime = frameIdx / effectiveVideoFps;
-
         var channels = Configuration.AudioConfig.AudioChannels;
         var samplesNeeded = syncCalculator.GetNextFrameSamples();
 
         var audioBuffer = ArrayPool<float>.Shared.Rent(samplesNeeded * channels);
         try
         {
-            AudioMixer?.GenerateAudioForFrame(audioBuffer, samplesNeeded, frameTime, dspTimeBase);
+            AudioMixer?.GenerateAudioForFrame(audioBuffer, samplesNeeded);
             videoFFmpeg.WriteAudioSamples(audioBuffer, samplesNeeded);
         }
         finally
@@ -865,6 +873,8 @@ internal class RenderManager : MonoBehaviour
     private void StopFFmpeg(bool success)
     {
         endRequested = true;
+        if (success) AudioMixer?.Complete();
+        else AudioMixer?.Cancel();
         if (!success)
         {
             MarkCancelled();
@@ -1011,7 +1021,7 @@ internal class RenderManager : MonoBehaviour
 
         _frameReader?.Dispose();
         ResetFrameHookState();
-        AudioMixer?.Reset(); AudioMixer = null;
+        AudioMixer?.Dispose(); AudioMixer = null;
         SyncCalculator = null;
         
         AudioSpectrumGenerator.Clear();