[Bug]: XG MIDI playback is weird with external MIDI output

[Limyx826]

Version of OpenTTD

1.11.2 Windows 10 21H1

Expected result

Smooth playback of XG midi

Actual result

Botched playback of XG midi

Steps to reproduce

Change your MIDI output from default Windows to external MIDI out (e.g. Virtual MIDI Synth, etc.).
Just load Traditional Winter Holiday Music Pack from BaNaNaS and play auld lang syne, it is the most obvious case.
Play the midi file directly with a midi player and you will know.

[nielsmh]

Does the MIDI file in question have an XG system reset message in it? I haven't tested with that music set at all myself but I do have two XG synths so I'll test this later today.

[Limyx826]

According to the MIDI player I have it is XG.

[nielsmh]

There is definitely something going wrong, yes. I'm not entirely sure what it is, and I doubt it specifically has to do with the sequences being XG spec, but there might be something else with note on/off ordering that goes wrong somewhere in loading or playback. Because I definitely do get hanging notes with those tunes, and they don't hang when played by other software.

[nielsmh]

Tested a bit more. The hanging notes happen when I use a hardware port on both the win32 and the dmusic drivers, not when I use the Microsoft softsynth with either, but if I configure DirectMusic without a port at all (i.e. using the "default softsynth" rather than "softsynth as a MIDI device") the playback breaks even more, missing several instruments. Possibly because the MIDI is selecting a bank containing no sounds, and instead of falling back on the default bank it just plays silence instead.

[Limyx826]

The same in openttd-20240130-master-g96651b5ada-windows-win64.