[pulseaudio-discuss] Can't get pulseaudio to use alsa/dmix?

Alex Malinovich demonbane at the-love-shack.net
Fri Oct 12 11:23:08 PDT 2007

On Fri, 2007-10-12 at 09:41 -0700, Marc MERLIN wrote:
> Howdy,
> I have pulseaudio 0.9.5-5ubuntu4 with the esd socket symlink fix.
> When pulseaudio starts, it seems to take over alsa exclusively.
> I'm not sure if adding "sink_name=output device=dmix" on output
> module-alsa-sink is necesary, or not, but in either case, pulseaudio seems
> to take exclusively over my alsa device.
> Just for info, my current alsa config seems to have dmix on by default.
> for i in 1 2 3; do alsaplayer file.mp3 & done
> works fine, I get 3 audio streams.

I'm not sure if it's a problem or not, but I've noticed that you have
both module-oss and module-alsa set to autoload. I suppose it might be
possible that pulse is actually using the OSS emulated device from ALSA,
but that's just speculation on my part.

On the other hand, if your soundcard doesn't do hardware mixing on its
own and requires the use of dmix, from personal experience I'd suggest
ditching dmix altogether and going with pulse for everything instead.
Pulse is much quicker at doing stream mixing in my experience. I
recently tried using a combination of pulse and dmix by setting up my
front two channels (which show up as a separate device from the rear two
through alsa) to be dedicated to pulse, while using dmix to allow
multiple apps access to the rear channels, and the delay on the rear was
quite noticeable. I then tried setting up dmix for both front and rear
without even using pulse at all, and I still ended up getting delays
between the front and rear. Made watching a surround-sound movie very...
interesting... :)

So I've just been using pulse for everything with my default alsa device
in my .asoundrc set to the pulse device and everything works great.
There are a couple of apps which don't use the virtual ALSA device
properly (notably virtualbox), but almost all the rest are just fine.
While mplayer has a native pulse driver now, doing mplayer -ao alsa
works just fine as well, going through the virtual alsa device.

Alex Malinovich
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