[alsa-devel] dmix produces garbled sound on ARM

[Takashi Iwai]

On Mon, 13 Jun 2016 14:32:30 +0200,
Ihar Filipau wrote:
> 
> On 6/9/16, Takashi Iwai <tiwai at suse.de> wrote:
> > On Thu, 09 Jun 2016 16:05:42 +0200,
> > Ihar Filipau wrote:
> >>
> >> The only thing so far I have found is `aplay --dump-hw-params`, but it
> >> seem to display the allowed ranges, not the defaults/the params which
> >> are used.
> >
> > You just need to check what "aplay -v ..." shows.  For example,
> > % aplay -Dplug:dmix -v foo.wav
> 
> I have just retested it with the "aloop", completely without hardware.
> The garbled sound comes from the software, from the dmix/libasound.
> The problem is not related to (sound) hardware.

Still it is likely a driver problem.  dmix updates are based on ALSA
PCM slave timer, i.e. it's synced with PCM period elapses.  That is,
if the driver updates at a wrong timing, sending the notification
before the sample data has been processed, you'll get the garbled
output as you have.


Takashi