//const int SndOutPacketSize = 512;
//short[] Buffer = new short[2 * 1024];
// Frame = 2 * sizeof(ushort)
// Period = is the number of frames in between each hardware interrupt. The poll() will return once a period.
// PeriodsPerBuffer
public AudioAlsaImpl()
{
if (_playbackHandle != IntPtr.Zero)
{
return;
}
try
{
fixed(IntPtr *playbackHandlePtr = &_playbackHandle)
fixed(IntPtr * hwParamsPtr = &_hwParams)
{
var rate = SampleRate;
//int period_time = (SndOutPacketSize * 1000) / (SampleRate / 1000);
//int buffer_time = period_time * NumBuffers;
Assert("snd_pcm_open",
Alsa.snd_pcm_open(playbackHandlePtr, Device,
Alsa.snd_pcm_stream_t.SND_PCM_LB_OPEN_PLAYBACK, 0));
Assert("snd_pcm_hw_params_malloc", Alsa.snd_pcm_hw_params_malloc(hwParamsPtr));
Assert("snd_pcm_hw_params_any", Alsa.snd_pcm_hw_params_any(_playbackHandle, _hwParams));
Assert("snd_pcm_hw_params_set_access",
Alsa.snd_pcm_hw_params_set_access(_playbackHandle, _hwParams,
Alsa.snd_pcm_access.SND_PCM_ACCESS_RW_INTERLEAVED));
Assert("snd_pcm_hw_params_set_format",
Alsa.snd_pcm_hw_params_set_format(_playbackHandle, _hwParams,
Alsa.snd_pcm_format.SND_PCM_FORMAT_S16_LE));
Assert("snd_pcm_hw_params_set_rate_near",
Alsa.snd_pcm_hw_params_set_rate_near(_playbackHandle, _hwParams, &rate, null));
//Assert("snd_pcm_hw_params_set_buffer_time_near", Alsa.snd_pcm_hw_params_set_buffer_time_near(playback_handle, hw_params, &buffer_time, null));
//Assert("snd_pcm_hw_params_set_period_time_near", Alsa.snd_pcm_hw_params_set_period_time_near(playback_handle, hw_params, &period_time, null));
Assert("snd_pcm_hw_params_set_channels",
Alsa.snd_pcm_hw_params_set_channels(_playbackHandle, _hwParams, Channels));
Assert("snd_pcm_hw_params_set_periods",
Alsa.snd_pcm_hw_params_set_periods(_playbackHandle, _hwParams, Periods, 0));
Assert("snd_pcm_hw_params_set_period_size",
Alsa.snd_pcm_hw_params_set_period_size(_playbackHandle, _hwParams, Periodsize, null));
Assert("snd_pcm_hw_params_set_buffer_size",
Alsa.snd_pcm_hw_params_set_buffer_size(_playbackHandle, _hwParams, 4 * Periodsize));
Assert("snd_pcm_hw_params", Alsa.snd_pcm_hw_params(_playbackHandle, _hwParams));
Assert("snd_pcm_hw_params_free", Alsa.snd_pcm_hw_params_free(_hwParams));
}
}
catch (Exception exception)
{
Console.Error.WriteLine(exception);
}
//available_start = Alsa.snd_pcm_avail_update(playback_handle);
}
//public int available_start;
public override void Update(Action <short[]> readStream)
{
readStream(Buffer);
fixed(short *bufferPtr = &Buffer[0])
{
if (Alsa.snd_pcm_state(_playbackHandle) == Alsa._snd_pcm_state.SND_PCM_STATE_XRUN)
{
Alsa.snd_pcm_prepare(_playbackHandle);
}
Alsa.snd_pcm_writei(_playbackHandle, bufferPtr, Buffer.Length / Channels);
}
}