Re: dmix plugin

[Takashi Iwai <tiwai@suse.de>]

At Wed, 12 Feb 2003 20:21:31 +0100 (CET),
Jaroslav wrote:
> 
> On Wed, 12 Feb 2003, Marc Titinger wrote:
> 
> > This looks Great !
> > 
> > I haven't yet experimented a lot with .asoundrc files, so please excuse
> > me if the following questions are irrelevant or OTO, but:
> > 
> > I was wondering if one could define a plug pcm, that offers two stereo
> > pairs routed with policy "average" to a single-stereo "hw" slave.
> > 
> > My understanding is that until this dmix pcm, there was no "official"
> > means supported by alsalib to achieve software mix of streams comming
> > from differents apps.
> 
> Yes, that's true.

well, route (or plug) has the capability for software mix (in a
certain meaning), but not for separate pcm streams.  you can downmix
the multi-channels in a stream via route plugin if the channels is
given.

but it's defenitely different from what dmix plugin does, and perhaps
it's different from what Marc wants, too...


> > Could I have one app open the first pair of my hypothetic plug pcm, and
> > another app open the second pair ? I guess this would be managed like a
> > concurrent access to a pcm, and block or fail the second open() call.
> > 
> > Would'nt it be nice to create a dmix pcm "behind"  a such plug pcm, to
> > provide mix in a transparent way ?
> 
> Some cards with multiple open hardware acceleration doesn't need this 
> default. Also, the dmix plugin has some limited things so I don't prefer 
> to select it as default.

agreed here, although i feel it's also nice to set it as default for a
consumer card which has no hardware mix function.

please note that you can re-define the default in asoundrc.
if you want to set up dmix as the system default, you can define it in
/etc/asound.conf, too.


Takashi


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