Ability to transpose MIDI signal up or down

Your idea

There would be a way to transpose the MIDI signal from a part up or down without altering the notation. For exemple, add a -1 transposition, play MIDI note 64, but the instrument receive the instruction to play the note 63.

Problem to be solved

This would allow for more control over midi playback, like when using a soundfont or VST at A415 you might want to transpose MIDI instead of pitch shifting.

I also allows you to fake other instruments using the "transpose then pitch shift back" method, used to fake instruments of weird transposition, and fake unison playing without messing up the notation part.

Prior art

This is a feature present in many DAWs, with very simple implementation.

Additional context

No response

Start by locating the MIDI playback path and existing notation transposition handling in MuseScore's C++ code. Define how a part-level MIDI-only offset should be represented without changing notation, then add coverage for notes transposed up and down and verify playback with soundfont or VST scenarios.