fix: tremolo articulation mapping for individual string instruments

[manolo]

Summary

Now string instruments correctly select tremolo MIDI presets when using SF2 soundfonts.

• Add missing tremolo articulation mappings to individual VIOLIN, VIOLA, VIOLONCELLO and CONTRABASS in soundmapping.h
• Previously only the *_SECTION variants had tremolo mappings, so individual instruments fell back to the default arco sound

Affected mappings

• VIOLIN: Tremolo8th/16th/32nd/64th to midi::Program(20, 44)
• VIOLA: Tremolo8th/16th/32nd/64th to midi::Program(30, 44)
• VIOLONCELLO: Tremolo8th/16th/32nd/64th to midi::Program(40, 44)
• CONTRABASS: Tremolo8th/16th/32nd/64th to midi::Program(50, 44)

Resolves: #21122

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• Each commit's message describes its purpose and effects, and references the issue it resolves
• If changes are extensive, there is a sequence of easily reviewable commits
• The code in the PR follows the coding rules
• There are no unnecessary changes
• The code compiles and runs on my machine, preferably after each commit individually
• I created a unit test or vtest to verify the changes I made (if applicable)
  • Does not apply because the change only affects configuration entries, no logic code, and there are no existing tests covering these mappings

[cbjeukendrup]

The samples that would be used by this PR are section samples, not solo, right? As far as I know, we don't have solo tremolo samples.

So a solo violin with tremolo would now use the section tremolo sound. We'll have to ask the design team what they prefer: solo+tremolo just using the solo sound without tremolo (current situation) or solo+tremolo using the section+tremolo sound (this PR).

[MarcSabatella]

FWIW, MU3 and earlier did it this way - section tremolo sounds for solo instrument - and we rarely if ever got complaints. To me it's very clearly preferable.

[manolo]

@cbjeukendrup thanks for bringing up this design consideration! You're right that the samples would be section samples, not solo. Using Bank 0, Program 44 (generic tremolo) for individual is perhaps more academic and also would have these advantages:

• No "hacks" in the instrument configuration files
• Users can select soundfonts that have the appropriate programs in the correct banks or develop their own.

@MarcSabatella Thanks for the historical context about MU3 behavior

In any way I can adapt my SF2 files for plectro Spanish orchestras to be able to reproduce tremolo correctly.

Would you like me to update the PR to use Bank 0 for individual instruments instead?

[manolo]

After investigating the playback code further, the instruments.xml file is no longer used for actual sound mapping. The real playback logic uses soundmapping.h.

I've rolled back changes regardin the .xml file. Now the PR is more concise.

[manolo]

Closed in favour of musescore/muse_framework#263, which targets the project this code was migrated to.

[Jojo-Schmitz]

Maybe you could reopen and rebase to 4.7 (which doesn't use muse_framework)?

[manolo]

@Jojo-Schmitz reopened, rebased and retargeted to 4.7