VGM to MIDI, then back to VGM - possible? by kooz at 6:19 AM EST on December 22, 2021
I'm somewhat familiar with the challenges that would be involved with this, but here are my thoughts:
I'm looking for a way to quantize the music from Sonic 1 and 2. There is obviously some sort of weird timing issue with the music in these games (and possibly/probably others). It's most noticeable (in my opinion) on the staff roll for both games, but seems to be present in some form throughout both soundtracks. It seems almost like a timing judder, like a framerate mismatch between a display and the content (i.e. 50 FPS video @ 60 Hz). Perhaps this is due to system load or some internal clock that does not play nicely with the songs' BPM; I'm not sure.
Anyway, what I'd love to be able to do is convert the VGMs into some sort of editable format. It doesn't have to be MIDI, but I am most familiar with it. From there, I would re-time the events to match with the song's intended BPM, quantize them, do any necessary manual adjustments, and finally convert that sequence data back to the original VGM format, for playback on hardware or other VGM players.
I know VGM to MIDI converters exist in some form, but going back the other way would be the hard part. My idea for a theoretical MIDI to VGM converter would involve using a "donor" VGM for instrument information, and it would expect the sequence data from the MIDI file to have the same number of tracks/channels as it's VGM counterpart.