Change in Jack behaviour on upgrade to Ardour 8.4

Installation & Configuration Linux
#1

I recently upgraded ubuntu studio from 22.04 LTS to 24.04 LTS. Along with that, Ardour upgraded to “rev 8.4.0~ds1-2ubuntu8 Intel 64-bit”.

Before upgrade the behaviour was:

  1. wait for Jack to start shortly after booting laptop
  2. start carla, observe my Scarlett 2i2 audio interface and keyboards in the patchbay
  3. start ardour
  4. continue to see my Scarlett 2i2 and keyboards in the patchbay
  5. be able to work in the patchbay sharing the Scarlett 2i2 between ardour and other things

After upgrade the behaviour is:

  1. wait for Jack to start shortly after booting laptop
  2. start carla, observe my Scarlett 2i2 audio interface and keyboards in the patchbay
  3. start ardour
  4. continue to see keyboards in the patchbay, but not my Scarlett 2i2
  5. ardour works with the Scarlett 2i2 but I am unable to use the patchbay to share it with other things.

It appears that ardour is getting exclusive control over the 2i2 jack channels.

Has anyone seen anything similar?
Is there any configuration I can change to return to the previous behaviour?

#2

Did they move from JACK/Pulse to PipeWire? That would change some things…

#3

The default sound server for Ubuntu Studio changed to Pipewire for version 24.04, so you may need a program like qpwgraph (Qt) or Helvum (GTK) to serve as a patchbay for the audio interface. Hopefully someone here that uses that distro can provide more specific advice.

You stated that Ardour is taking exclusive control of the audio interface. Are you using the ALSA or JACK backend when you start a session? ALSA will take exclusive control by design. In order to use a patch bay, you would need to select JACK instead.

#4

OMG I should have caught that - you’re probably right. I just noticed that Ardour doesn’t appear in my jack patchbay anymore and there doesn’t appear to be anyway to choose the transport method.

#5

Thanks @GuntherT, yes you must be right. I’ll poke around a little in the distro. Sorry for having wasted everyone’s time, and thanks for the help

#6

For anyone watching, here is a summary of the resolution:

For some reason with the new version of ardour or the import of my old sessions were using the ALSA backend. So I had to go into ardour->edit->preferences->general->audio/midi setup and

  1. uncheck "try to auto-launch audio/midi engine, and
  2. “Show Audio/MIDI setup Window” and select JACK as the audio system

After this, the previous behaviour was restored.

I don’t know anything about Pipewire, but it seems to be an effort to make Jack based audio central to the distro. As a result both qpwgraph and carla have working patch bays - but I like the carla plugin rack, so I’ll probably stick with it.

Thanks for your help

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