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Re: Sound on multi-user system

On Thu, Jan 13, 2011 at 10:26:38PM +0100, Yann Dirson wrote:

> It's been some time I've been annoyed by a problem that google reveals
> is not so uncommon, but for which a solution seems to be quite hard to
> find: letting the user currently active on a seat to use the sound
> card, as long as no other really uses it.

I'm not sure I completely understand the problem in question. Normally,
if a user logs in, a lot of magic with console-kit (or policy-kit?) is
triggered to grant access to the soundcard. From there on, the user more
or less "owns" the card.

Do you now say that other users could also login and should get access
to the soundcard without the first user logging off? Something like the
"switch user" stuff modern desktop environments support?

I don't know if they somehow share access to audio, but I guess they
should. We really need to talk to the pulseaudio guys to get this right,
and I'm pretty confident that it's doable. (I'm not familiar with
consumer desktops)

With regard to jackd: leave it out of the equation. jackd is for
producing audio, it runs in very specific environments, let's think of a
recording studio for a while. Switching users normally doesn't happen.

So there's no use in bothering Paul Davis in #ardour with all this. He's
doing pro-audio, and though he might know one thing or the other that
might improve your situation, the real guy to talk to is Lennart
Poettering or first the Debian pulseaudio maintainers.

Sharing cards between pulseaudio and jackd doesn't really work reliably
atm, the pro guys usually stop (or pasuspend) pulseaudio and fire up
jackd, but most of them don't even have pulseaudio, some of them don't
even have X. (think of streaming/capture servers in broadcasting

The sad thing is: everything mentioned above works on OSX, multiple
users can access the soundcard, pro-users can start their pro-apps which
go nicely side by side with the consumer tools and the lot.

Somebody has suggested Paul and Lennart should meet and get paid for
merging jackd and pulseaudio, but it seems that's not going to happen.
Technically, it's not impossible (see OSX), but we're talking money
here. Give Paul a salary, and he might take care. ;)

Just my €0.02

mail: adi@thur.de  	http://adi.thur.de	PGP/GPG: key via keyserver

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