/// <summary>
/// Clean up the SecondaryBuffer
/// </summary>
/// <remarks>
/// <para>
/// In DirectSound, when playback is started,
/// the rest of the sound that was played last time is played back as noise.
/// This happens even if the secondary buffer is completely silenced,
/// so it seems that the buffer in the primary buffer or higher is not cleared.
/// </para>
/// <para>
/// To solve this problem fill the secondary buffer with silence data when stop playback.
/// </para>
/// </remarks>
private void CleanUpSecondaryBuffer()
{
if (secondaryBuffer != null)
{
byte[] silence = new byte[samplesTotalSize];
// Lock the SecondaryBuffer
IntPtr wavBuffer1;
int nbSamples1;
IntPtr wavBuffer2;
int nbSamples2;
secondaryBuffer.Lock(0, (uint)samplesTotalSize,
out wavBuffer1, out nbSamples1,
out wavBuffer2, out nbSamples2,
DirectSoundBufferLockFlag.None);
// Copy silence data to the SecondaryBuffer
if (wavBuffer1 != IntPtr.Zero)
{
Marshal.Copy(silence, 0, wavBuffer1, nbSamples1);
if (wavBuffer2 != IntPtr.Zero)
{
Marshal.Copy(silence, 0, wavBuffer1, nbSamples1);
}
}
// Unlock the SecondaryBuffer
secondaryBuffer.Unlock(wavBuffer1, nbSamples1, wavBuffer2, nbSamples2);
}
}
/// <summary>
/// Feeds the SecondaryBuffer with the WaveStream
/// </summary>
/// <param name="bytesToCopy">number of bytes to feed</param>
private int Feed(int bytesToCopy)
{
int bytesRead = bytesToCopy;
// Restore the buffer if lost
if (IsBufferLost())
{
secondaryBuffer.Restore();
}
// Clear the bufferSamples if in Paused
if (playbackState == PlaybackState.Paused)
{
Array.Clear(samples, 0, samples.Length);
}
else
{
// Read data from stream (Should this be inserted between the lock / unlock?)
bytesRead = waveStream.Read(samples, 0, bytesToCopy);
if (bytesRead == 0)
{
Array.Clear(samples, 0, samples.Length);
return(0);
}
}
// Lock a portion of the SecondaryBuffer (starting from 0 or 1/2 the buffer)
IntPtr wavBuffer1;
int nbSamples1;
IntPtr wavBuffer2;
int nbSamples2;
secondaryBuffer.Lock(nextSamplesWriteIndex, (uint)bytesRead, // (uint)bytesToCopy,
out wavBuffer1, out nbSamples1,
out wavBuffer2, out nbSamples2,
DirectSoundBufferLockFlag.None);
// Copy back to the SecondaryBuffer
if (wavBuffer1 != IntPtr.Zero)
{
Marshal.Copy(samples, 0, wavBuffer1, nbSamples1);
if (wavBuffer2 != IntPtr.Zero)
{
Marshal.Copy(samples, 0, wavBuffer1, nbSamples1);
}
}
// Unlock the SecondaryBuffer
secondaryBuffer.Unlock(wavBuffer1, nbSamples1, wavBuffer2, nbSamples2);
return(bytesRead);
}