public static void WriteCallback(SoundIOOutStream stream, int frameCountMin, int frameCountMax)
{
SoundIoError err;
DateTime callbackTime = DateTime.Now;
// loop to utilize as much as the frameCountMax as possible
while (frameCountMax > 0)
{
int frameCount = frameCountMax;
if ((err = stream.BeginWrite(out SoundIOChannelAreas areas, ref frameCount)) != SoundIoError.None)
{
Console.WriteLine("unrecoverable stream error: {0}", err.GetErrorMessage());
_fileDone = true;
}
if (frameCount == 0)
{
break;
}
var bufferCount = frameCount * stream.Layout.ChannelCount;
// if buffer is done add silence based on latency to allow stream to complete through
// audio path before stream is Disposed()
if (_waveFile.Position >= _waveFile.Length)
{
if (_startSilence)
{
// windows latency is a little higher (using DateTime to determine the callback time delay)
// and needs to be accoutned for...
_latencySeconds -= (DateTime.Now - callbackTime).TotalMilliseconds / 1000.0;
_silentSamplesRemaining = (int)((stream.SampleRate * stream.Layout.ChannelCount) * _latencySeconds);
_silentSamplesRemaining -= _silentSamplesAlreadySent;
_startSilence = false;
}
int silentBufferSize;
if (_silentSamplesRemaining > bufferCount)
{
silentBufferSize = bufferCount;
_silentSamplesRemaining -= bufferCount;
}
else
{
silentBufferSize = _silentSamplesRemaining;
_silentSamplesRemaining = 0;
}
if (silentBufferSize > 0)
{
// create a new buffer initialized to 0 and copy to native buffer
var silenceBuffer = new float[silentBufferSize];
stream.CopyTo(silenceBuffer, 0, areas, silentBufferSize);
}
if (_silentSamplesRemaining == 0)
{
_fileDone = true;
stream.EndWrite();
stream.Pause(true);
return;
}
// if the remaining audioBuffer will only partially fill the frameCount
// copy the remaining amount and set the startSilence flag to allow
// stream to play to the end.
}
else if (_waveFile.Position + (frameCount * _waveFile.WaveFormat.Channels) >= _waveFile.Length)
{
float[] audioBuffer = new float[bufferCount];
var actualSamplesRead = _sampleProvider.Read(audioBuffer, 0, bufferCount);
stream.CopyTo(audioBuffer, 0, areas, bufferCount);
_silentSamplesAlreadySent = bufferCount - actualSamplesRead;
_latencySeconds = 0.0;
_startSilence = true;
}
else
{
// copy audioBuffer data to native buffer and advance the bufferPos
float[] audioBuffer = new float[bufferCount];
var actualSamplesRead = _sampleProvider.Read(audioBuffer, 0, bufferCount);
stream.CopyTo(audioBuffer, 0, areas, actualSamplesRead);
if (_waveFile.Position >= _waveFile.Length)
{
_latencySeconds = 0.0;
_startSilence = true;
}
}
if ((err = stream.EndWrite()) != SoundIoError.None)
{
if (err == SoundIoError.Underflow)
{
return;
}
Console.WriteLine("Unrecoverable stream error: {0}", err.GetErrorMessage());
_fileDone = true;
}
if (_startSilence)
{
// get actual latency in order to compute number of silent frames
stream.GetLatency(out _latencySeconds);
callbackTime = DateTime.Now;
}
// loop until frameCountMax is used up
frameCountMax -= frameCount;
}
return;
}