[pulseaudio-discuss] pulseaudio

Tanu Kaskinen tanuk at iki.fi
Tue Apr 12 09:53:46 PDT 2011

On Tue, 2011-04-12 at 12:30 -0400, Sean McNamara wrote:
> Hi,
> On Tue, Apr 12, 2011 at 12:15 PM, duportail <poort at telenet.be> wrote:
> > Try to test the new xubuntu 11.04 with kde on a multi-user system.
> > The first user (for example user1) can log in and gets a default sink from
> > pulse.
> > The second user(for example user2) that will log in gets a auto_null because
> > pulse did not found any sinks.
> > If i log out user1, than user2 can get a default sink by kill and start
> > pulse.
> > Where should be the reason?
> This is the "classic" multi-user problem: you're using a soundcard
> without hardware mixing, so only one ALSA application can take direct
> control of the hardware device at a time. user1's pulseaudio daemon
> takes control of it, so obviously user2's PA daemon will just get
> "Device or resource busy" when trying to snd_pcm_open() on hw:0 (for
> example). This problem has existed since ALSA existed. There's no
> direct fix without scrapping the API and rewriting it.

Actually, this situation is supposed to be handled just fine (unless
duportail expects both users to be able to use the audio hw
simultaneously, which he doesn't mention). If this doesn't work, xubuntu
is broken. Some things that can cause this problem: the users are in the
"audio" group, consolekit isn't running or consolekit's udev-acl isn't
in use.


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