[pulseaudio-discuss] pulseaudio

duportail poort at telenet.be
Tue Apr 12 09:50:36 PDT 2011

Op 12-4-2011 18:30, Sean McNamara schreef:
> 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.
> I guess there is no solution yet (still) in 11.04, but you can see
> that folks in the Ubuntu community are trying to resolve the issue
> with a number of possible approaches:
> https://wiki.edubuntu.org/BluePrints/multiuser-soundcards-pulseaudio
> Running as system-wide is one possible approach...
> http://www.pulseaudio.org/wiki/SystemWideInstance
> Not sure if there's yet a solution allowing the use of shm and
> module-native-protocol-unix for multiple users (this is ideally what
> you'd want for maximum performance / minimum latency), but it's quite
> easy to set up module-native-protocol-tcp and connect to localhost
> using the `default-server' parameter in client.conf, at the cost of
> latency. Let me know if you need more details on this particular
> approach.
> BTW, search the archives of this list at gmane<
> http://blog.gmane.org/gmane.comp.audio.pulseaudio.general>  -- there
> are many many historical posts about multi-user setups.
> Sean
>> gd
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Sorry, forgot to mention: there multiple (two) usb soundcards on the 
system.It is working good on xubuntu 10.10.
As you said, the second user gets a "Device or resource busy".When I 
logout the first user, the second user can get a default sink.

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