[alsa-devel] AD1988B: ALSA doesn't use dmix automatically

A. C. Censi accensi at gmail.com
Mon Mar 17 15:08:48 CET 2008

On Mon, Mar 17, 2008 at 8:45 AM, Takashi Iwai <tiwai at suse.de> wrote:
> At Sat, 15 Mar 2008 23:48:52 -0300,
> Dâniel Fraga wrote:
> >
> > ALSA 1.0.15
> >
> > http://alsa.opensrc.org/index.php/Dmix
> >
> > NOTE: For ALSA 1.0.9rc2 and higher you don't need to setup dmix. Dmix
> > is enabled as default for soundcards which don't support hw mixing.
> >
> >       So why if I try to play 2 sounds at the same time, the second
> > one complains the "resource is busy"? Shouldn't it detect that AD1988B
> > can't do hardware mixing and use dmix automatically?
> It does as long as the app uses the "default" PCM.  The dmix isn't
> forced to be applied.  The exclusive hardware access is still
> available by opening the PCM as "hw", "plughw" and etc.  So, if any
> apps access exclusively, others will suffer.

Applications normally offer the real devices as first choices and not
the "default" PCM. Perhaps this should be explained better in the
documentation or the wiki, not only for the end users, but also for
application developers.

A. C. Censi
accensi [em] gmail [ponto] com
accensi [em] montreal [ponto] com [ponto] br

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