[alsa-devel] Join play of pcm in multiple playback devices
pierre-louis.bossart at linux.intel.com
Tue Jan 3 22:32:23 CET 2012
> retval=snd_pcm_readi(pAlsaConfig->pcm_handle, buffer,
> snd_pcm_writei(pAlsaConfig->pcm_handle1, buffer,retval);
> snd_pcm_writei(pAlsaConfig->pcm_handle2, buffer,retval);
This code doesn't work in the general case where the different devices
don't share a common audio clock and have different physical
capture/playback rates. Compensating for clock drift requires the use of
asynchronous sample-rate conversion.
Assuming you have a perfectly synchronous system, you could make use of
snd_pcm_delay() to compensate for delays incurred in the
driver/firmware/hardware. This is not well supported by all drivers though.
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