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Fixing QJackCtl

Posted: Aug 16, 2015 12:08;
Last Modified: Aug 16, 2015 12:08

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A really brief note on how to fix a problem with qjackctl not starting jackd. If you don’t understand this, then it isn’t relevant for you.

Contents

The problem: QJackCtl can’t start the JACK server

Was having trouble with QJackctl (a daemon for running Jack, connection software required for media production software within Ubuntu):

1) D-BUS: JACK server could not be started. Sorry
2) Could not connect to JACK server as client. - Overall operation failed. - Unable to connect to server. Please check the messages window for more info.

Screenshots of the error


Output of message

12:14:54.591 Patchbay deactivated.
12:14:54.593 Statistics reset.
12:14:54.598 ALSA connection change.
12:14:54.606 D-BUS: Service is available (org.jackaudio.service aka jackdbus).
Cannot connect to server socket err = No such file or directory
Cannot connect to server request channel
jack server is not running or cannot be started
12:14:54.614 ALSA connection graph change.
12:14:57.883 D-BUS: JACK server could not be started. Sorry
Cannot connect to server socket err = No such file or directory
Cannot connect to server request channel
jack server is not running or cannot be started
Sun Aug 16 12:14:57 2015: Starting jack server...
Sun Aug 16 12:14:57 2015: JACK server starting in realtime mode with priority 10
Sun Aug 16 12:14:57 2015: self-connect-mode is "Don't restrict self connect requests"
Sun Aug 16 12:14:57 2015: ERROR: cannot register object path "/org/freedesktop/ReserveDevice1/Audio0": A handler is already registered for /org/freedesktop/ReserveDevice1/Audio0
Sun Aug 16 12:14:57 2015: ERROR: Failed to acquire device name : Audio0 error : A handler is already registered for /org/freedesktop/ReserveDevice1/Audio0
Sun Aug 16 12:14:57 2015: ERROR: Audio device hw:0 cannot be acquired...
Sun Aug 16 12:14:57 2015: ERROR: Cannot initialize driver
Sun Aug 16 12:14:57 2015: ERROR: JackServer::Open failed with -1
Sun Aug 16 12:14:57 2015: ERROR: Failed to open server
Sun Aug 16 12:14:59 2015: Saving settings to "/home/dan/.config/jack/conf.xml" ...
12:15:17.033 Could not connect to JACK server as client. - Overall operation failed. - Unable to connect to server. Please check the messages window for more info.
Cannot connect to server socket err = No such file or directory
Cannot connect to server request channel
jack server is not running or cannot be started

The solution

The first of these error messages is widely reported and seems to cause a ton of trouble. Suggestions includie klilling pulseaudio and restarting things; making sure you’ve been added to the audio user group; making sure that there is an audio group (i.e. that JACK has access to a real time kernel. Here are some sites I visited that deal with common issues involving this error, none of which were the actual problem for me, though they have useful advice on things to look for):

In my case, the problem turned out to be simply an issue in the qjackctl settings. I needed to explicitly say which sound card it was to use, as indicated telegraphically here: http://ubuntuforums.org/showthread.php?t=2238377&p=13093181#post13093181

How to fix the settings:

1) In a terminal start qjackctl: > qjackctl

2) Before you try to start it, click the “setup” button in the GUI (right hand side, middle).

3) On the setup GUI change “Input Device” and “Output Device” (middle, right hand side) from “(Default)” to “HW:PCH” (In the screenshot one has been changed and the other not).

4) Restart qJackCtl. You should now be able to successfully use the “Start” button.

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