private unsafe void Update(IntPtr userdata, IntPtr stream, int streamLength)
{
Span <byte> streamSpan = new Span <byte>((void *)stream, streamLength);
int maxFrameCount = (int)GetSampleCount(streamLength);
int bufferedFrames = _ringBuffer.Length / _bytesPerFrame;
int frameCount = Math.Min(bufferedFrames, maxFrameCount);
if (frameCount == 0)
{
// SDL2 left the responsability to the user to clear the buffer.
streamSpan.Fill(0);
return;
}
byte[] samples = new byte[frameCount * _bytesPerFrame];
_ringBuffer.Read(samples, 0, samples.Length);
samples.AsSpan().CopyTo(streamSpan);
streamSpan.Slice(samples.Length).Fill(0);
// Apply volume to written data
SDL_MixAudioFormat(stream, stream, _nativeSampleFormat, (uint)samples.Length, (int)(_volume * SDL_MIX_MAXVOLUME));
ulong sampleCount = GetSampleCount(samples.Length);
ulong availaibleSampleCount = sampleCount;
bool needUpdate = false;
while (availaibleSampleCount > 0 && _queuedBuffers.TryPeek(out SDL2AudioBuffer driverBuffer))
{
ulong sampleStillNeeded = driverBuffer.SampleCount - Interlocked.Read(ref driverBuffer.SamplePlayed);
ulong playedAudioBufferSampleCount = Math.Min(sampleStillNeeded, availaibleSampleCount);
ulong currentSamplePlayed = Interlocked.Add(ref driverBuffer.SamplePlayed, playedAudioBufferSampleCount);
availaibleSampleCount -= playedAudioBufferSampleCount;
if (currentSamplePlayed == driverBuffer.SampleCount)
{
_queuedBuffers.TryDequeue(out _);
needUpdate = true;
}
Interlocked.Add(ref _playedSampleCount, playedAudioBufferSampleCount);
}
// Notify the output if needed.
if (needUpdate)
{
_updateRequiredEvent.Set();
}
}
private unsafe void Update(int minFrameCount, int maxFrameCount)
{
int bytesPerFrame = _outputStream.BytesPerFrame;
uint bytesPerSample = (uint)_outputStream.BytesPerSample;
int bufferedFrames = _ringBuffer.Length / bytesPerFrame;
int frameCount = Math.Min(bufferedFrames, maxFrameCount);
if (frameCount == 0)
{
return;
}
SoundIOChannelAreas areas = _outputStream.BeginWrite(ref frameCount);
int channelCount = areas.ChannelCount;
byte[] samples = new byte[frameCount * bytesPerFrame];
_ringBuffer.Read(samples, 0, samples.Length);
// This is a huge ugly block of code, but we save
// a significant amount of time over the generic
// loop that handles other channel counts.
// TODO: Is this still right in 2021?
// Mono
if (channelCount == 1)
{
SoundIOChannelArea area = areas.GetArea(0);
fixed(byte *srcptr = samples)
{
if (bytesPerSample == 1)
{
for (int frame = 0; frame < frameCount; frame++)
{
((byte *)area.Pointer)[0] = srcptr[frame * bytesPerFrame];
area.Pointer += area.Step;
}
}
else if (bytesPerSample == 2)
{
for (int frame = 0; frame < frameCount; frame++)
{
((short *)area.Pointer)[0] = ((short *)srcptr)[frame * bytesPerFrame >> 1];
area.Pointer += area.Step;
}
}
else if (bytesPerSample == 4)
{
for (int frame = 0; frame < frameCount; frame++)
{
((int *)area.Pointer)[0] = ((int *)srcptr)[frame * bytesPerFrame >> 2];
area.Pointer += area.Step;
}
}
else
{
for (int frame = 0; frame < frameCount; frame++)
{
Unsafe.CopyBlockUnaligned((byte *)area.Pointer, srcptr + (frame * bytesPerFrame), bytesPerSample);
area.Pointer += area.Step;
}
}
}
}
// Stereo
else if (channelCount == 2)
{
SoundIOChannelArea area1 = areas.GetArea(0);
SoundIOChannelArea area2 = areas.GetArea(1);
fixed(byte *srcptr = samples)
{
if (bytesPerSample == 1)
{
for (int frame = 0; frame < frameCount; frame++)
{
// Channel 1
((byte *)area1.Pointer)[0] = srcptr[(frame * bytesPerFrame) + 0];
// Channel 2
((byte *)area2.Pointer)[0] = srcptr[(frame * bytesPerFrame) + 1];
area1.Pointer += area1.Step;
area2.Pointer += area2.Step;
}
}
else if (bytesPerSample == 2)
{
for (int frame = 0; frame < frameCount; frame++)
{
// Channel 1
((short *)area1.Pointer)[0] = ((short *)srcptr)[(frame * bytesPerFrame >> 1) + 0];
// Channel 2
((short *)area2.Pointer)[0] = ((short *)srcptr)[(frame * bytesPerFrame >> 1) + 1];
area1.Pointer += area1.Step;
area2.Pointer += area2.Step;
}
}
else if (bytesPerSample == 4)
{
for (int frame = 0; frame < frameCount; frame++)
{
// Channel 1
((int *)area1.Pointer)[0] = ((int *)srcptr)[(frame * bytesPerFrame >> 2) + 0];
// Channel 2
((int *)area2.Pointer)[0] = ((int *)srcptr)[(frame * bytesPerFrame >> 2) + 1];
area1.Pointer += area1.Step;
area2.Pointer += area2.Step;
}
}
else
{
for (int frame = 0; frame < frameCount; frame++)
{
// Channel 1
Unsafe.CopyBlockUnaligned((byte *)area1.Pointer, srcptr + (frame * bytesPerFrame) + (0 * bytesPerSample), bytesPerSample);
// Channel 2
Unsafe.CopyBlockUnaligned((byte *)area2.Pointer, srcptr + (frame * bytesPerFrame) + (1 * bytesPerSample), bytesPerSample);
area1.Pointer += area1.Step;
area2.Pointer += area2.Step;
}
}
}
}
// Surround
else if (channelCount == 6)
{
SoundIOChannelArea area1 = areas.GetArea(0);
SoundIOChannelArea area2 = areas.GetArea(1);
SoundIOChannelArea area3 = areas.GetArea(2);
SoundIOChannelArea area4 = areas.GetArea(3);
SoundIOChannelArea area5 = areas.GetArea(4);
SoundIOChannelArea area6 = areas.GetArea(5);
fixed(byte *srcptr = samples)
{
if (bytesPerSample == 1)
{
for (int frame = 0; frame < frameCount; frame++)
{
// Channel 1
((byte *)area1.Pointer)[0] = srcptr[(frame * bytesPerFrame) + 0];
// Channel 2
((byte *)area2.Pointer)[0] = srcptr[(frame * bytesPerFrame) + 1];
// Channel 3
((byte *)area3.Pointer)[0] = srcptr[(frame * bytesPerFrame) + 2];
// Channel 4
((byte *)area4.Pointer)[0] = srcptr[(frame * bytesPerFrame) + 3];
// Channel 5
((byte *)area5.Pointer)[0] = srcptr[(frame * bytesPerFrame) + 4];
// Channel 6
((byte *)area6.Pointer)[0] = srcptr[(frame * bytesPerFrame) + 5];
area1.Pointer += area1.Step;
area2.Pointer += area2.Step;
area3.Pointer += area3.Step;
area4.Pointer += area4.Step;
area5.Pointer += area5.Step;
area6.Pointer += area6.Step;
}
}
else if (bytesPerSample == 2)
{
for (int frame = 0; frame < frameCount; frame++)
{
// Channel 1
((short *)area1.Pointer)[0] = ((short *)srcptr)[(frame * bytesPerFrame >> 1) + 0];
// Channel 2
((short *)area2.Pointer)[0] = ((short *)srcptr)[(frame * bytesPerFrame >> 1) + 1];
// Channel 3
((short *)area3.Pointer)[0] = ((short *)srcptr)[(frame * bytesPerFrame >> 1) + 2];
// Channel 4
((short *)area4.Pointer)[0] = ((short *)srcptr)[(frame * bytesPerFrame >> 1) + 3];
// Channel 5
((short *)area5.Pointer)[0] = ((short *)srcptr)[(frame * bytesPerFrame >> 1) + 4];
// Channel 6
((short *)area6.Pointer)[0] = ((short *)srcptr)[(frame * bytesPerFrame >> 1) + 5];
area1.Pointer += area1.Step;
area2.Pointer += area2.Step;
area3.Pointer += area3.Step;
area4.Pointer += area4.Step;
area5.Pointer += area5.Step;
area6.Pointer += area6.Step;
}
}
else if (bytesPerSample == 4)
{
for (int frame = 0; frame < frameCount; frame++)
{
// Channel 1
((int *)area1.Pointer)[0] = ((int *)srcptr)[(frame * bytesPerFrame >> 2) + 0];
// Channel 2
((int *)area2.Pointer)[0] = ((int *)srcptr)[(frame * bytesPerFrame >> 2) + 1];
// Channel 3
((int *)area3.Pointer)[0] = ((int *)srcptr)[(frame * bytesPerFrame >> 2) + 2];
// Channel 4
((int *)area4.Pointer)[0] = ((int *)srcptr)[(frame * bytesPerFrame >> 2) + 3];
// Channel 5
((int *)area5.Pointer)[0] = ((int *)srcptr)[(frame * bytesPerFrame >> 2) + 4];
// Channel 6
((int *)area6.Pointer)[0] = ((int *)srcptr)[(frame * bytesPerFrame >> 2) + 5];
area1.Pointer += area1.Step;
area2.Pointer += area2.Step;
area3.Pointer += area3.Step;
area4.Pointer += area4.Step;
area5.Pointer += area5.Step;
area6.Pointer += area6.Step;
}
}
else
{
for (int frame = 0; frame < frameCount; frame++)
{
// Channel 1
Unsafe.CopyBlockUnaligned((byte *)area1.Pointer, srcptr + (frame * bytesPerFrame) + (0 * bytesPerSample), bytesPerSample);
// Channel 2
Unsafe.CopyBlockUnaligned((byte *)area2.Pointer, srcptr + (frame * bytesPerFrame) + (1 * bytesPerSample), bytesPerSample);
// Channel 3
Unsafe.CopyBlockUnaligned((byte *)area3.Pointer, srcptr + (frame * bytesPerFrame) + (2 * bytesPerSample), bytesPerSample);
// Channel 4
Unsafe.CopyBlockUnaligned((byte *)area4.Pointer, srcptr + (frame * bytesPerFrame) + (3 * bytesPerSample), bytesPerSample);
// Channel 5
Unsafe.CopyBlockUnaligned((byte *)area5.Pointer, srcptr + (frame * bytesPerFrame) + (4 * bytesPerSample), bytesPerSample);
// Channel 6
Unsafe.CopyBlockUnaligned((byte *)area6.Pointer, srcptr + (frame * bytesPerFrame) + (5 * bytesPerSample), bytesPerSample);
area1.Pointer += area1.Step;
area2.Pointer += area2.Step;
area3.Pointer += area3.Step;
area4.Pointer += area4.Step;
area5.Pointer += area5.Step;
area6.Pointer += area6.Step;
}
}
}
}
// Every other channel count
else
{
SoundIOChannelArea[] channels = new SoundIOChannelArea[channelCount];
// Obtain the channel area for each channel
for (int i = 0; i < channelCount; i++)
{
channels[i] = areas.GetArea(i);
}
fixed(byte *srcptr = samples)
{
for (int frame = 0; frame < frameCount; frame++)
{
for (int channel = 0; channel < areas.ChannelCount; channel++)
{
// Copy channel by channel, frame by frame. This is slow!
Unsafe.CopyBlockUnaligned((byte *)channels[channel].Pointer, srcptr + (frame * bytesPerFrame) + (channel * bytesPerSample), bytesPerSample);
channels[channel].Pointer += channels[channel].Step;
}
}
}
}
_outputStream.EndWrite();
ulong sampleCount = (ulong)(samples.Length / bytesPerSample / channelCount);
ulong availaibleSampleCount = sampleCount;
bool needUpdate = false;
while (availaibleSampleCount > 0 && _queuedBuffers.TryPeek(out SoundIoAudioBuffer driverBuffer))
{
ulong sampleStillNeeded = driverBuffer.SampleCount - Interlocked.Read(ref driverBuffer.SamplePlayed);
ulong playedAudioBufferSampleCount = Math.Min(sampleStillNeeded, availaibleSampleCount);
Interlocked.Add(ref driverBuffer.SamplePlayed, playedAudioBufferSampleCount);
availaibleSampleCount -= playedAudioBufferSampleCount;
if (Interlocked.Read(ref driverBuffer.SamplePlayed) == driverBuffer.SampleCount)
{
_queuedBuffers.TryDequeue(out _);
needUpdate = true;
}
Interlocked.Add(ref _playedSampleCount, playedAudioBufferSampleCount);
}
// Notify the output if needed.
if (needUpdate)
{
_updateRequiredEvent.Set();
}
}