Enable VST in CI Linux build

[cbjeukendrup]

It is believed that it works well enough nowadays to expose it to users.

[cbjeukendrup]

@DmitryArefiev Let's see if this is in a state that's acceptable to expose to users. Most likely, it won't be perfect, and not all plugins may work. Maybe, that will always be the case, on Linux. On the other hand, certain users are desperately waiting for VST support on Linux. So if this does not introduce problematic situations for the users who are not interested in VST on Linux, let's merge it, to make the users who do want it happy.

[DmitryArefiev]

@cbjeukendrup I've installed Vital VSTi (it's VST3, what we are support) but MSS doesn't see that instrument in Mixer.
And Reaper (DAW) detects fine Vital instrument on my Linux Ubuntu

[diedeno]

I don't see any vst3 in this build.
Vital does work in my build. (but i have no use for it). Of course, a small number of native Linux vst3 do not work at all. (e.g. because we cannot handle multi-plugins, like LSP on Linux -- or (i guess) on Windows Waves)

[igorkorsukov]

@cbjeukendrup I remembered, VST is disabled by default, we need to enable it..

https://github.com/musescore/MuseScore/blob/master/src/framework/cmake/MuseDeclareOptions.cmake#L63

UPD: Although this will be enabled for all developers, now the SDK downloads itself, there is no need to download it and configure paths.. but on the other hand, it is not necessary for developers and will slow down the configuration and assembly of the project a little.
I think it is better to simply enable VST on CI (return options in the build scripts)

[cbjeukendrup]

Sorry, second attempt.

[diedeno]

Seems to work fine. (sometimes, a restart of MuseScore is needed for newly added vst's)

[DmitryArefiev]

Tested on LinuxUbuntu24.04.2 LTS. I've tested on Vital VSTi and Dragonfly reverb VSTe (both VST3).
They detected fine in Mixer but both are crashing when trying to open
MuseScore_250615_154416.zip

@cbjeukendrup Should be logged separately?

[cbjeukendrup]

@igorkorsukov what do you think?
It would be difficult for me to work on this, because I don't have Linux currently. So it would be great if you or someone else could take this over from me. But would it be okay to merge this to master already?

[diedeno]

Like i said: often a restart is needed with a newly scanned plugin. First time it crashes.
On my system (ubuntu 24.04), both these plugins work with this build, as well as dozens others.
Lots of plugins crash (including vital) when they are replaced with something else. But this is also the case in Windows or Mac it seems. e.g. #24529
e.g; U-he plugins always crash when replaced.
Maybe because the apparently very minimal removePluginModule

void VstModulesRepository::removePluginModule(const muse::audio::AudioResourceId& resourceId)
{
ONLY_MAIN_THREAD(threadSecurer);
std::lock_guard lock(m_mutex);
m_modules.erase(resourceId);
}

The thing is far from perfect, no doubt. But lots of plugins never crash (e.g. Decent sampler).
If we wait until everything is perfect, we will never see this enabled.
Enabling this will allow to fix problems.

[igorkorsukov]

what do you think?
It would be difficult for me to work on this, because I don't have Linux currently. So it would be great if you or someone else could take this over from me. But would it be okay to merge this to master already?

I'll take a look and I'll write later

[igorkorsukov]

I found out this:

• On my build on Qt 6.9 the mixer doesn't work, the combo boxes for selecting a sound or effect don't open.
• On Qt 6.2 Vital opens without problems, but freezes when closing (I think this is a specific problem for Vital on Linux). Dragonfly opens and closes without problems.

I think this PR can be merged and the problems can be registered separately.

[DmitryArefiev]

On my build on Qt 6.9 the mixer doesn't work, the combo boxes for selecting a sound or effect don't open.

Yes, it's probably similar to #28352. But you can open those boxes with navigation

I think this PR can be merged and the problems can be registered separately.

Yes, I'll log them separately