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BizHawk
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Detect and recover from buffer underflow, i.e. resynchronize the write position so that our writes always end up just before the play cursor.

This commit is contained in:
jdpurcell 2015-01-17 01:56:23 +00:00
parent c3a4077ffb
commit f1480740e3
1 changed files with 39 additions and 11 deletions
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50
BizHawk.Client.EmuHawk/Sound.cs
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@ -1,5 +1,7 @@
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Threading;
#if WINDOWS
using SlimDX.DirectSound;
@ -40,7 +42,9 @@ namespace BizHawk.Client.EmuHawk
private const int SampleRate = 44100;
private const int BytesPerSample = 2;
private const int ChannelCount = 2;
private const int BufferSize = (SampleRate / 10) * BytesPerSample * ChannelCount; // 1/10th of a second
private const int BlockAlign = BytesPerSample * ChannelCount;
private const int BufferSize = (SampleRate / 10) * BlockAlign; // 1/10th of a second
private const double BufferDuration = (double)(BufferSize / BlockAlign) / SampleRate;
private bool _muted;
private bool _disposed;
@ -49,6 +53,9 @@ namespace BizHawk.Client.EmuHawk
private ISoundProvider _asyncSoundProvider;
private ISyncSoundProvider _syncSoundProvider;
private int _actualWriteOffset = -1;
private int _filledBufferSize;
private long _lastWriteTime;
private int _lastWriteCursor;
public Sound(IntPtr handle, DirectSound device)
{
@ -62,8 +69,8 @@ namespace BizHawk.Client.EmuHawk
BitsPerSample = BytesPerSample * 8,
Channels = ChannelCount,
FormatTag = WaveFormatTag.Pcm,
BlockAlignment = BytesPerSample * ChannelCount,
AverageBytesPerSecond = SampleRate * BytesPerSample * ChannelCount
BlockAlignment = BlockAlign,
AverageBytesPerSecond = SampleRate * BlockAlign
};
var desc = new SoundBufferDescription
@ -137,16 +144,36 @@ namespace BizHawk.Client.EmuHawk
private int CalculateSamplesNeeded()
{
int playOffset = _deviceBuffer.CurrentPlayPosition;
int writeOffset = _deviceBuffer.CurrentWritePosition;
long currentWriteTime = Stopwatch.GetTimestamp();
int playCursor = _deviceBuffer.CurrentPlayPosition;
int writeCursor = _deviceBuffer.CurrentWritePosition;
if (_actualWriteOffset != -1)
{
double elapsedTime = (currentWriteTime - _lastWriteTime) / (double)Stopwatch.Frequency; // Seconds
int cursorDelta = CircularDistance(_lastWriteCursor, writeCursor, BufferSize);
cursorDelta += BufferSize * (int)Math.Round((elapsedTime - (cursorDelta / (double)(SampleRate * BlockAlign))) / BufferDuration);
_filledBufferSize -= cursorDelta;
if (_filledBufferSize < 0)
{
// Buffer underflow
_actualWriteOffset = -1;
}
}
if (_actualWriteOffset == -1)
{
_actualWriteOffset = writeOffset;
_actualWriteOffset = writeCursor;
_filledBufferSize = 0;
}
_lastWriteTime = currentWriteTime;
_lastWriteCursor = writeCursor;
int bytesNeeded = (playOffset - _actualWriteOffset + BufferSize) % BufferSize;
return bytesNeeded / (BytesPerSample * ChannelCount);
int bytesNeeded = CircularDistance(_actualWriteOffset, playCursor, BufferSize);
return bytesNeeded / BlockAlign;
}
private int CircularDistance(int start, int end, int size)
{
return (end - start + size) % size;
}
public void UpdateSilence()
@ -192,7 +219,7 @@ namespace BizHawk.Client.EmuHawk
if (!Global.DisableSecondaryThrottling)
while (samplesNeeded < samplesProvided)
{
System.Threading.Thread.Sleep((samplesProvided - samplesNeeded) / (SampleRate / 1000)); // let audio clock control sleep time
Thread.Sleep((samplesProvided - samplesNeeded) / (SampleRate / 1000)); // let audio clock control sleep time
samplesNeeded = CalculateSamplesNeeded();
}
}
@ -214,7 +241,8 @@ namespace BizHawk.Client.EmuHawk
return;
_deviceBuffer.Write(samples, 0, samplesProvided * ChannelCount, _actualWriteOffset, LockFlags.None);
_actualWriteOffset = (_actualWriteOffset + (samplesProvided * BytesPerSample * ChannelCount)) % BufferSize;
_actualWriteOffset = (_actualWriteOffset + (samplesProvided * BlockAlign)) % BufferSize;
_filledBufferSize += samplesProvided * BlockAlign;
}
/// <summary>