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Thread: cannot use real-time scheduling with jack

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  1. #1
    Join Date
    Oct 2008

    Question cannot use real-time scheduling with jack

    I've had horrible audio problems with Ubuntu since I got this laptop, an HP Pavilion dv7, about 8 months ago. I get audio dropouts and skips associated with ANY cpu usage. So, I'm now determined to fix it and get more control and ability to run more than one audio app at a time with realtime JACK.

    I'm getting this when I try to start from qtjackctl ...

    08:00:51.943 /usr/bin/jackd -R -dalsa -dhw:0 -r44100 -p64 -n2 -m
    08:00:51.946 JACK was started with PID=5774.
    no message buffer overruns
    jackd 0.116.1
    Copyright 2001-2005 Paul Davis and others.
    jackd comes with ABSOLUTELY NO WARRANTY
    This is free software, and you are welcome to redistribute it
    under certain conditions; see the file COPYING for details
    JACK compiled with System V SHM support.
    cannot use real-time scheduling (FIFO at priority 10) [for thread -2120620304, from thread -2120620304] (1: Operation not permitted)
    cannot create engine
    I have linux-rt and linux-headers-rt installed on a 64-bit fully updated Jaunty and I believe that my user has permissions ...

    root@lappy:~# cat /etc/security/limits.conf | grep @audio
    @audio          -       rtprio          99
    @audio		-	memlock		unlimited
    @audio		-	nice		-19
    root@lappy:~# cat /etc/group | grep audio
    anybody know what else I can try or look at to solve this?

    Steve Maring

  2. #2
    Join Date
    Apr 2008
    Ubuntu 9.10 Karmic Koala

    Re: cannot use real-time scheduling with jack

    Are you a member of the group audio?
    PMs will be ignored.

  3. #3
    Join Date
    Aug 2007
    Los Angeles, CA
    Ubuntu 14.04 Trusty Tahr

    Re: cannot use real-time scheduling with jack

    You're running JACK at 64 frames/period. This is a very low setting for a laptop's integrated sound card (which I'm assuming you're using). With professional or prosumer gear you can achieve this sort of performance easily, but I recommend experimenting with higher settings first and then working your way down. Try 1024 frames/period and see if that makes an improvement. It will increase your latency but it will greatly reduce xruns (which cause the dropouts). Also, people with Intel sound cards commonly report that using 3 periods/buffer helps. To find out if yours is an Intel chip, type:
    sudo lshw -C multimedia
    One other thing--be sure restart the system after configuring /etc/security/limits.conf so the settings are applied to your session the next time you log in.

  4. #4
    Join Date
    Jun 2006

    Re: cannot use real-time scheduling with jack

    What soundcard and drivers are you using?

  5. #5
    Join Date
    Feb 2008

    Re: cannot use real-time scheduling with jack

    $ uname -r

    Ubuntu 8.04 - the Hardy Heron

    $ sudo lshw -C multimedia
    description: Multimedia audio controller
    product: 82801BA/BAM AC'97 Audio Controller
    vendor: Intel Corporation
    physical id: 1f.5
    bus info: pci@0000:00:1f.5
    version: 05
    width: 32 bits
    clock: 33MHz
    capabilities: bus_master
    configuration: driver=Intel ICH latency=0 module=snd_intel8x0

    For me works the question of are you in the sound group? but not exactly so.

    I change two things in my user and groups configuration. Now I really do not know exactly what of this action make sense. I will prove them one by one in next reboots.

    The actions were (both in Users and groups GNOME menu):
    1. Give to my user the privilegies for use audio equipment. I do not undestand this really because I use audio in my laptop as normal users for 10 months.
    2. In the group option I have added to the three groups which names starting with "pulse" my user (enable the check square).

    I rebooted and the jack server starts with out problems.


  6. #6
    Join Date
    Jul 2012

    Re: cannot use real-time scheduling with jack

    In the group option I have added to the three groups which names starting with "pulse" my user (enable the check square).
    This is what I was missing, thanks!!

  7. #7
    Join Date
    Feb 2008
    Ubuntu Gnome Development Release

    Re: cannot use real-time scheduling with jack

    Thread closed. Please do not post in old threads.

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