Fix N64 audio weirdness in AVI recording.

BizHawk.Client.EmuHawk/BizHawk.Client.EmuHawk.csproj

@@ -731,6 +731,7 @@
     <Compile Include="Sound\Output\XAudio2SoundOutput.cs" />
     <Compile Include="Sound\Sound.cs" />
     <Compile Include="Sound\Utilities\BufferedAsync.cs" />
+    <Compile Include="Sound\Utilities\SyncToAsyncProvider.cs" />
     <Compile Include="Sound\Utilities\SoundOutputProvider.cs" />
     <Compile Include="Throttle.cs" />
     <Compile Include="ToolAttributes.cs" />

BizHawk.Client.EmuHawk/MainForm.cs

@@ -3142,8 +3142,9 @@ namespace BizHawk.Client.EmuHawk
 				else
 				{
 					_currentSoundProvider.SetSyncMode(SyncSoundMode.Sync);
-					_aviSoundInputAsync = new MetaspuAsync(_currentSoundProvider, ESynchMethod.ESynchMethod_V);
-				}					
+					double msPerFrame = 1000.0 * Emulator.CoreComm.VsyncDen / Emulator.CoreComm.VsyncNum;
+					_aviSoundInputAsync = new SyncToAsyncProvider(_currentSoundProvider, msPerFrame + 10.0);
+				}
 			}
 			_dumpProxy = new SimpleSyncSoundProvider();
 			RewireSound();

BizHawk.Client.EmuHawk/Sound/Utilities/SyncToAsyncProvider.cs

@@ -0,0 +1,83 @@
+using System;
+using System.Collections.Generic;
+
+using BizHawk.Emulation.Common;
+
+namespace BizHawk.Client.EmuHawk
+{
+	public class SyncToAsyncProvider : ISoundProvider
+	{
+		private const int SampleRate = 44100;
+		private const int ChannelCount = 2;
+		private const double MinExpectedFrameRate = 50;
+
+		private readonly SoundOutputProvider _outputProvider = new SoundOutputProvider();
+		private readonly int _bufferSizeSamples;
+		private readonly Queue<short> _buffer;
+
+		public SyncToAsyncProvider(ISoundProvider baseProvider, double bufferSizeMs)
+		{
+			_outputProvider.BaseSoundProvider = baseProvider;
+			_bufferSizeSamples = (int)Math.Ceiling(bufferSizeMs * SampleRate / 1000.0);
+			_buffer = new Queue<short>((_bufferSizeSamples + (int)Math.Ceiling(SampleRate / MinExpectedFrameRate)) * ChannelCount);
+
+			DiscardSamples();
+		}
+
+		public void DiscardSamples()
+		{
+			_buffer.Clear();
+			_outputProvider.DiscardSamples();
+
+			for (int i = 0; i < _bufferSizeSamples * ChannelCount; i++)
+			{
+				_buffer.Enqueue(0);
+			}
+		}
+
+		public void GetSamplesAsync(short[] samples)
+		{
+			GetSamplesFromBase(samples.Length / ChannelCount);
+			for (int i = 0; i < samples.Length; i++)
+			{
+				samples[i] = _buffer.Dequeue();
+			}
+		}
+
+		public bool CanProvideAsync
+		{
+			get { return true; }
+		}
+
+		public SyncSoundMode SyncMode
+		{
+			get { return SyncSoundMode.Async; }
+		}
+
+		public void SetSyncMode(SyncSoundMode mode)
+		{
+			if (mode != SyncSoundMode.Async)
+			{
+				throw new NotSupportedException("Sync mode is not supported.");
+			}
+		}
+
+		public void GetSamplesSync(out short[] samples, out int nsamp)
+		{
+			throw new InvalidOperationException("Sync mode is not supported.");
+		}
+
+		private void GetSamplesFromBase(int minResultingSampleCount)
+		{
+			int idealSampleCount = Math.Max(_bufferSizeSamples + minResultingSampleCount - (_buffer.Count / ChannelCount), 0);
+			short[] samples;
+			int samplesProvided;
+			_outputProvider.MaxSamplesDeficit = _bufferSizeSamples;
+			_outputProvider.GetSamples(idealSampleCount, out samples, out samplesProvided);
+			for (int i = 0; i < samplesProvided * ChannelCount; i++)
+			{
+				_buffer.Enqueue(samples[i]);
+			}
+		}
+	}
+}