Re: [LAU] JACK and realtime in Ubuntu 7.10

Peter Clarke wrote:
> I'm having problems with realtime in JACK in my newly installed Ubuntu 7.10.
>
> If I start qjackctl as a normal user - even the user with "admin" privileges -
> I cannot start the jack server in realtime mode. The error is:
>
> cannot use real-time scheduling (FIFO at priority 10) [for thread -1210406208,
> from thread -1210406208] (1: Operation not permitted)
>
> But if I start qjackctl with sudo, realtime works fine.
>
> I remember from my previous Gentoo system that I had to install modules
> realtime and realtime-lsm, and the user had to be a member of group realtime.
> But none of that seems to apply to Ubuntu, because it uses a specially
> patched kernel; am I correct about that?
>
> Output of uname -a is:
> Linux peter-desktop 2.6.22-14-rt #1 SMP PREEMPT RT Mon Oct 15 01:05:51 GMT
> 2007 i686 GNU/Linux
>
> The jackd command generated by qjackctl is:
> /usr/bin/jackd -R -dalsa -r44100 -p1024 -n4 -D -Chw:0,0 -Phw:0,0 -s -S -i2 -o2
>
> So my question is: how can I run jack as a normal user in Ubuntu?

The easy way is to install the ubuntustudio packages that are part of
the normal ubuntu repository. apt-get install ubuntustudio-audio should
do the trick.

The thing to ensure is that your /etc/security/limits.conf contains
these lines:

@audio - rtprio 99
@audio - memlock 512000
@audio - nice -19

and that your user is part of the 'audio' group (it normally is by
default).

Normally the ubuntustudio packages take care of both these conditions.
Note that should you have to add the lines or make your user member of
the audio group, you have to logout and relogin in order for the changes
to take effect.

Greets,

Pieter

PS: While you're at it you can also install the realtime patched kernel
for ubuntu (linux-rt).
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Received on Sun Dec 2 16:15:01 2007