Cannot create Audio/MIDI engine

… for any libardour based command-line tool (ardour6-export, ardour6-copy-mixer) and various backend audio systems on Fedora 33. Ardour version 6.3.

When I open a session, play, record, … work with the configured audio system, everything is fine. But when closing the session/ quitting Ardour and calling ardour6-copy-mixer or ardour6-export from command line, an error message “Cannot create Audio/MIDI engine” pops up and the tool ends immediately. This holds for multiple backend systems. I’ve tried JACK, Pulseaudio, and ALSA without any change in behaviour. No issue in GUI, but “Cannot create Autio/MIDI engine” for any of the mentioned headless tools.
Starting up jackd external (keeping it up running) doesn’t make a difference either.

Is this a know problem? Anything obviously wrong with my configuration? Any other idea what’s going on?

Thanks,
Toby

First up, are you using a version of Ardour 6.3 from this website or from a Fedora repo?

The commandline tools rely on the dummy backend (libdummy_audiobackend.so), and are only built when the dummy backed is available.

In the past Fedora packaged backends separately, perhaps that is again the case?

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Looks to be the case again?: http://fedora.c3sl.ufpr.br/linux/updates/testing/33/Everything/aarch64/Packages/a/ardour6-backend-dummy-6.3.0-1.fc33.aarch64.rpm

Thanks Robin, you saved my day!
Yes, I’m using the Fedora packages and dummy backend isn’t installed by default, because ardour6 package is lacking this dependency. Once added manually, the tools do work. Confirmed!

I’ve already submitted a bug report on Fedory bugzilla about this packaging issue. Now it’s up to the package maintainer to fix the dependencies or repackage appropriately (I’d simply merge the dummy backend to the main package, as it’s tiny and doesn’t bring new dependencies to the main one).