[alsa-devel] libao problem (Re: No dmix/dsnoop on Intel ICH4/5 by default?)

Rene Herman rene.herman at gmail.com
Thu Jan 17 11:22:27 CET 2013

On 16-01-13 21:52, Clemens Ladisch wrote:

> Rene Herman wrote:

>> I'm out of touch of with alsa -- but should dmix/dsnoop still be
>> enabled by default on hardware that doesn't do hardware mixing?
> Yes.
>> I believe that it should be from /usr/share/alsa/cards/ICH4.conf,
>> but I don't get mixing on this setup when using the "default"
>> pcm...
> What's the output of "aplay -v something.wav"?

I won't bother you with that, since things do in fact work with aplay. 
It seems I'm looking at a libao problem.

Specifically: I can mix as many streams as I want using just "aplay" but 
if I start by playing one track with "ogg123" (which uses a default, 
unconfigured libao as its backend), I can't start a second ogg123, which 
then says:

ao_alsa WARNING: Unable to open surround playback.  Trying default device...
ALSA lib pcm_dmix.c:1018:(snd_pcm_dmix_open) unable to open slave
ao_alsa ERROR: Unable to open ALSA device 'default' for playback => 
Device or resource busy
ERROR: Cannot open device alsa.

I CAN still start an "aplay" at this point though. Moreover, things get 
weirder when I start with aplay. With one aplay running, I CAN start two 
additional ogg123 instances.

... so, err, ehm, err, what? :-)

This now seems at best related to ALSA in a secondary manner, and I'm 
CCing this to vorbis-dev (which I believe is the right email contact for 
libao?) but if you know of something of interest...

For vorbis-dev: this is on arch linux, (standard) kernel 3.6.11-1-ARCH, 
alsa-{lib,plugins,utils}-1.0.26-1, libao-1.1.0-2 and vorbis-tools-1.4.0-3.


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