Ubuntu – “Jack audio server could not be started” in QJackCtl

dbusjackpulseaudiosound

I have been trying to start the JACK audio server in QJackCtl, but I get the message:

DBUS: Jack server could not be started.
Sorry

So the symptoms of my problem are exactly the same as in this question or this question. However, none of the solutions named in those questions answers worked for me:

  • When I do sudo qjackctl, nothing changes at all.

  • When I do

    pulseaudio --kill

jack_control start

    I get:

    DBus exception: org.jackaudio.Error.Generic: Failed to open server

Any help would be highly appreciated as the existing answers couldn't help me. I am using Ubuntu 14.04 (64-bit).

Here is the error log of QJackCtl:

Cannot connect to server socket err = Datei oder Verzeichnis nicht gefunden
Cannot connect to server request channel
jack server is not running or cannot be started
Sun Sep 27 22:17:50 2015: Starting jack server...
Sun Sep 27 22:17:50 2015: JACK server starting in realtime mode with priority 10
Sun Sep 27 22:17:50 2015: ERROR: Cannot lock down 82274202 byte memory area (Cannot allocate memory)
Sun Sep 27 22:17:50 2015: ERROR: cannot register object path "/org/freedesktop/ReserveDevice1/Audio0": A handler is already registered for /org/freedesktop/ReserveDevice1/Audio0
Sun Sep 27 22:17:50 2015: ERROR: Failed to acquire device name : Audio0 error : A handler is already registered for /org/freedesktop/ReserveDevice1/Audio0
Sun Sep 27 22:17:50 2015: ERROR: Audio device hw:0 cannot be acquired...
Sun Sep 27 22:17:50 2015: ERROR: Cannot initialize driver
Sun Sep 27 22:17:50 2015: ERROR: JackServer::Open failed with -1
Sun Sep 27 22:17:50 2015: ERROR: Failed to open server
Sun Sep 27 22:17:51 2015: Saving settings to "/home/username/.config/jack/conf.xml" ...

Best Answer

Has it worked before now? Try using Cadence from kx-studio. I had lots of headache trying to run Qjackctl. Discovered Cadence, and bingo! Everything settled. First purge whatever jack you have before installing Cadence. Check here. http://kxstudio.linuxaudio.org/Repositories

Can you check the log through Cadence? Is it same error? I did not document the steps I took then.

If you use pulseaudio, you may have to install pulseaudio-module-jack. Only use jack2

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