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I installed JACK and qjackctl on Ubuntu 20.04. Now jackd starts on startup, which means that my normal (non-DAW) applications can't produce sound until I run sudo killall jackd.

There's no sign of JACK or jackd in the Ubuntu startup applications, nor in sudo service --status-all, nor in sudo systemctl list-unit-files, nor crontab -e or sudo crontab -e, nor ls /etc/init.d/.

I think that's actually all of the Ubuntu software startup mechanisms I'm aware of, so this is a great learning opportunity for me: how on earth is this daemon starting itself? And how can I disable it?

EDIT: Found this in /var/log/syslog: https://pastebin.com/ApsMfvUd . Maybe this has to do with pulseaudio configuration?

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    Did you add any of your DAW-applications which rely on jackd to your startup-applications?
    – mook765
    Commented Feb 17, 2021 at 3:14
  • Good thought! The only one is Bitwig Studio, and bitwig doesn't appear in any of the areas I listed above. But I do notice pulseaudio-enable-autospawn enabled in sudo systemctl list-unit-files? Not sure if that is related?
    – brandones
    Commented Feb 18, 2021 at 16:14
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    No, that's not related, it just ensures that pulseaudio will be started. The problem is , while using jackd, pulseaudio is not connected to alsa (since jackd is). jackd should not be started at login at all unless an application in autostart is starting jackd via dbus. Did you look in ~/.config/autostart?
    – mook765
    Commented Feb 18, 2021 at 16:32
  • I hadn't! There's no JACK or Bitwig, but there is mpd.desktop, which may be related?
    – brandones
    Commented Feb 18, 2021 at 19:17
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    That could be related, you should try to temporary remove mpd.desktop from ~/.config/autostart and check if the problem persists.
    – mook765
    Commented Feb 18, 2021 at 22:28

1 Answer 1

Reset to default
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I had modified the PulseAudio configuration /etc/pulse/default.pa with the lines

load-module module-jack-sink
load-module module-jack-source

This was causing PulseAudio, which starts at startup, to try to start JACK at startup.

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    Yes, that's it. Just read your log and saw it too. Also consider to enable realtime permissions for jack. A nice way to configure jack is studio-controls, with default config it will manage the connections to run pulse and jack together and remember the state of jack (running or not) surviving reboots, that's pretty cool. I really prefer studio-controls over qjackctl, no need to write startup-scripts to run jack together with pulseaudio.
    – mook765
    Commented Feb 19, 2021 at 20:46
  • Nice, thanks so much for all your help through debugging this!
    – brandones
    Commented Feb 19, 2021 at 21:13

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