Interesting utility that might help with reversing Gamecube BMS files. by Basillica at 5:58 PM EDT on March 30, 2019
While looking around for attempts at reverse-engineering Pikmin's music, I found this utility that was made for Super Mario Sunshine that compiles MIDI into BMS files, among other things.
Recently, Xayrga made a tool for playback and it was posted here. It's not perfect, but it's easy to use and was a very exciting thing to see released!
A while ago I wrote a BMS synthesizer as part of gctools, which is also not perfect. Thanks for sharing the links; there's a lot of good documentation in arookas' repo... if I'm bored some weekend I might implement more of the register commands.