bool Alsa9Buf::SetHWParams()
{
int err;
if( dsnd_pcm_state(pcm) == SND_PCM_STATE_PREPARED )
dsnd_pcm_drop( pcm );
if( dsnd_pcm_state(pcm) != SND_PCM_STATE_OPEN )
{
/* Reset the stream to SND_PCM_STATE_OPEN. */
err = dsnd_pcm_hw_free( pcm );
ALSA_ASSERT("dsnd_pcm_hw_free");
}
// ASSERT_M( dsnd_pcm_state(pcm) == SND_PCM_STATE_OPEN, ssprintf("(%s)", dsnd_pcm_state_name(dsnd_pcm_state(pcm))) );
/* allocate the hardware parameters structure */
snd_pcm_hw_params_t *hwparams;
dsnd_pcm_hw_params_alloca( &hwparams );
err = dsnd_pcm_hw_params_any(pcm, hwparams);
ALSA_CHECK("dsnd_pcm_hw_params_any");
/* Set to interleaved mmap mode. */
err = dsnd_pcm_hw_params_set_access(pcm, hwparams, SND_PCM_ACCESS_MMAP_INTERLEAVED);
ALSA_CHECK("dsnd_pcm_hw_params_set_access");
/* Set the PCM format: signed 16bit, native endian. */
err = dsnd_pcm_hw_params_set_format(pcm, hwparams, SND_PCM_FORMAT_S16);
ALSA_CHECK("dsnd_pcm_hw_params_set_format");
/* Set the number of channels. */
err = dsnd_pcm_hw_params_set_channels(pcm, hwparams, 2);
ALSA_CHECK("dsnd_pcm_hw_params_set_channels");
/* Set the sample rate. */
err = dsnd_pcm_hw_params_set_rate_near(pcm, hwparams, &samplerate, 0);
ALSA_CHECK("dsnd_pcm_hw_params_set_rate_near");
/* Set the buffersize to the writeahead, and then copy back the actual value
* we got. */
writeahead = preferred_writeahead;
err = dsnd_pcm_hw_params_set_buffer_size_near( pcm, hwparams, &writeahead );
ALSA_CHECK("dsnd_pcm_hw_params_set_buffer_size_near");
/* The period size is roughly equivalent to what we call the chunksize. */
int dir = 0;
chunksize = preferred_chunksize;
err = dsnd_pcm_hw_params_set_period_size_near( pcm, hwparams, &chunksize, &dir );
ALSA_CHECK("dsnd_pcm_hw_params_set_period_size_near");
// LOG->Info("asked for %i period, got %i", chunksize, period_size);
/* write the hardware parameters to the device */
err = dsnd_pcm_hw_params( pcm, hwparams );
ALSA_CHECK("dsnd_pcm_hw_params");
return true;
}
/* If the given sample rate can be used, return it. Otherwise, return the
* samplerate to use instead. */
unsigned Alsa9Buf::FindSampleRate( unsigned rate )
{
snd_pcm_hw_params_t *testhw;
dsnd_pcm_hw_params_alloca( &testhw );
dsnd_pcm_hw_params_any( pcm, testhw );
int err = dsnd_pcm_hw_params_set_rate_near(pcm, testhw, &rate, 0);
if( err >= 0 )
return rate;
return 0;
}
