Linux Audio

When I started packaging music applications in Flatpak, I was confronted to the issue of audio plugins: lot of music software has effects, software instruments and others implemented as plugins colloquially called VST. When packaging Ardour, it became clear that supported these plugins where a necessity, as Ardour includes very little in term of instruments and effects.

On Linux there are 5 different formats: while LADSPA, DSSI and LV2 are open, VST2 and VST3 are proprietary standard, created by Steinberg, they are very popular in non-libre desktops and applications. Fortunately with somewhat open implementations available, they exist on Linux in open source form. These 5 audio plugins format work in whichever applications can host them. In general LV2 is preferred.

Now the problem is that "one doesn't simply drop a binary in a flatpak". I'm sure there are some tricks to install them, since a lot of plugins are standalone, but in general it's not sanctioned. So I came up with a proposal and an implementation to support and build Linux Audio plugins in Flatpak. I'll skip the details for now, as I'm working on a comprehensive guide, but the result is that several audio applications now support plugins in flatpak, and a good number of plugins are available on Flathub.

The music applications that support plugins in Flatpak are Muse3 (not to be confused with MuseScore), LMMS, Hydrogen, Ardour (this is not supported by the upstream project), Mixxx, gsequencer. Audacity is still pending. There is also a few video editors: kdenlive, Flowblade, and Shotcut that support LADSPA audio effects and can now use the packaged plugins.

Sadly there don't seem to be a way to find the plugins on Flathub web site, nor in GNOME Software (as found in Fedora). So to find available plugins, you have to use the command line:

$ flatpak search LinuxAudio


In the same idea, GIMP was lacking plugins. GMic has been the most requested plugin. So I took similar steps and submitted plugin support for GIMP as a flatpak. This was much less complicated as we don't have the problem of multiple apps. Then I packaged a few plugins, GMic being the most complex (we need to build Qt5). Now GIMP users have a few important third-party plugins available, including LensFun, Resynthesizer, Liquid Rescale and BIMP.

Thanks to all the flathub contributors and reviewers for the feedback, to the Ardour team for creating such an amazing application, and to Jehan for his patience as the GIMP flatpak maintainer.