[ERROR]: Found a reference to a plugin ("http://gareus.org/oss/lv2/gmsynth") that is unknown. about gmsynth.lv2

[hfiguiere]

I got Ardour from flathub, my distro is popOS, so I used its package manager.. That might be the problem, maybe I should try to install it from the source ( I admit I was lazy on this one)

Since you use the flatpak for Ardour, you might want to instead install org.freedesktop.LinuxAudio.Plugins.gmsynth which is the flatpaked version of gmsynth.

[hfiguiere]

In which I discover that setting LV2_PATH (in the sandbox) does prevent Ardour from looking into ~/.lv2 I will fix this and it should allow plugins installed in .lv2 to (possibly) work. This plugin would in that case.

[x42]

URIs in LV2 just serve as a unique identifier. They do not have to point to a valid web-page (but most do for convenience).
The unique ID of the general MIDI synth is http://gareus.org/oss/lv2/gmsynth and that has not changed, regardless of the web-page redirecting.

Where did you get Ardour from? binaries from http://ardour.org/download.html do bundle the plugin, but most GNU/Linux distributions do not include it.

Try lv2ls | grep gmsynth. If all is setup correctly that should print http://gareus.org/oss/lv2/gmsynth.

Canonical way to install the plugin (here using a pre-compiled 64bit Linux version):

cd /tmp
wget https://x42-plugins.com/x42/linux/x42-gmsynth-v0.5.0-x86_64.tar.gz
tar xvf x42-gmsynth-v0.5.0-x86_64.tar.gz
mkdir -p ~/.lv2
rm -rf ~/.lv2/gmsynth.lv2
mv x42-gmsynth/gmsynth.lv2/ ~/.lv2/

Then restart Ardour (lv2 plugins are indexed at application start).

[chris-carneiro]

Wow thanks for the very quick reply!

Here is the output
$ lv2ls | grep gmsynth
https://x42-plugins.com/x42/x42-gmsynth -- that's what I modified in the source but that means the plugin is resolved.

I got Ardour from flathub, my distro is popOS, so I used its package manager.. That might be the problem, maybe I should try to install it from the source ( I admit I was lazy on this one)

[x42]

OK. that's the wrong URI. the plugin's ID is http://gareus.org/oss/lv2/gmsynth.

In any case, flatpak is your issue. Flatpak sanboxes the application. This is conceptually at odds with the concept of 3rd party plugins. The plugin(s) also need to be in the same sandbox as the application to be found.

Please contact flatpak maintainers of the Ardour about it. The flatpak build is neither recommended nor endorsed by Ardour devs.

[chris-carneiro]

OK I got the right URL now but the issue remains.

I'll reinstalled Ardour and contact the flatpak maintainers with the reference to this issue (if you don't mind ? ) to see if they can do something about it.

Thanks for the input and your support.

[chris-carneiro]

I found a similar issue here in case anyone has the same error.

As you mentioned, Ardour should only be installed using the binaries found on the official website.
Thanks again for your time!