AD1988B: ALSA doesn't use dmix automatically

AD1988B: ALSA doesn't use dmix automatically

[Dâniel Fraga]

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? 

	Obs.: I don't have any ~/.asoundrc or /etc/asound.conf lying
around.

	Thanks!

-- 
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Re: AD1988B: ALSA doesn't use dmix automatically

[Takashi Iwai]

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.


Takashi

Re: AD1988B: ALSA doesn't use dmix automatically

[A. C. Censi]

On Mon, Mar 17, 2008 at 8:45 AM, Takashi Iwai <tiwai@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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Re: AD1988B: ALSA doesn't use dmix automatically

[Alexander E. Patrakov]

Takashi Iwai wrote:
> It does as long as the app uses the "default" PCM

...and a card-specific file exists under /usr/share/alsa/cards. This is not the 
case, e.g., for sb16 (just try it in qemu and compare with ens1370--qemu can 
emulate both of them).

-- 
Alexander E. Patrakov

Re: AD1988B: ALSA doesn't use dmix automatically

[Takashi Iwai]

At Mon, 17 Mar 2008 20:18:35 +0500,
Alexander E. Patrakov wrote:
> 
> Takashi Iwai wrote:
> > It does as long as the app uses the "default" PCM
> 
> ...and a card-specific file exists under /usr/share/alsa/cards. This is not the 
> case, e.g., for sb16 (just try it in qemu and compare with ens1370--qemu can 
> emulate both of them).

Well, it's basically a bug -- the config remains so because it wasn't
confirmed to work.  If it's OK on your system, let us know.  We'll
change the configuration.


Takashi