[pulseaudio-discuss] and the winner is dmix Re: Multiple users (kde) on Debian

Halim Sahin halim.sahin at freenet.de
Fri Aug 20 20:37:01 PDT 2010

Servus Jan,
On Mo, Jul 26, 2010 at 06:33:35 +0200, Jan Braun wrote:
> Colin Guthrie schrob:
> > 'Twas brillig, and Mark Cross at 26/07/10 15:23 did gyre and gimble:
> > > So, there must be a way "supported by maintainers" to have two PA instances
> > > form two users that share access to the sound system.
> > 
> > Sadly there is no officially recommended way to do this. This is
> > actually enforced at a lower level than PA with ConsoleKit ultimately
> > being responsible for writing the ACLs on the device nodes (via udev)
> > used for the sound h/w.
> >
> > ck-list-sessions will tell you which user is "active" and typically this
> > user will get access to various different resources on the machine by
> > virtue of them being active.
> That sounds like resources can never be shared. Which is what Mark and I
> are looking for.


> > PA simply listens to messages from CK and gracefully releases it's
> > control of the devices when it's not supposed to have access. In reality
> > we're just being a good citizen in this regard.
> Yep, but maybe CK isn't such a good police^Hy.

+1 if ck really doesn't support plain texconsole logins.

> > > The problem Pulseaudio was supposed to solve was to have mixing of several 
> > > streams, but in doing so, PA took total ownership of the sound hardware, 
> > > not allowing any other service to access the hardware, not even a second 
> > > instance of PA. That have just shift the mixing issue from ALSA to PA, with 
> > > seemingly equivalent basic problems. Yes, it has several interesting and 
> > > useful features, but I wonder: what is the "supported" way to have several 
> > > services access the sound system?
> None.
> Alsa supports[1] one application playing audio at a time.

Alsa can do softmixing as well with it's dmix plugin.
This worked well since pa takes exclusive access over the audio card.

> PA supports applications of one user playing at a time.
Yes and btw, it does this really well.
The pa developers anyway forgot that there are many other apps which
needs more flexibility than they are willing to offer.
It seems user-switching in kde is now only possible if the seccond user
doesn't want to play audio.
This is in my opinion not an improovment.
And yes I don't care about how mac or windows are doing things.
There are many examples what they did wrong in the past.


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