What follows below this line is the very old release of my ultra broken beta version. It should not be used, and it's only for archival purposes.
Download here. It is highly unfinished but I fail at postponing releases, so I can let you all have some fun with this. Happy early Christmas, I guess
It imports (almost) any MIDI file in format 0 to output VGM files. No PSG, no YM2413 (use ValleyBell's converter for that one), no YM2151 (yet, but I plan to add it soon, if I can understand the few docs available). Yes, it is technically possible to have 2612 and 2151 in the same vgm file, resulting into 6+8 FM channels at the same time. Neat, isn't it?
No YM2612 PCM channel, it's 6FM only. I won't make any guarantee about the PCM channel being added anytime soon if at all.
What works: Volume changes (via the Main Volume Controller), Pitch bends, Pan changes (via the Pan Controller), Instrument changes. Please note that I didn't finalize the instrument interface yet, so I'm relying on a temporary solution for now. Future versions will have a comprehensive instrument editor with parameters and whatnot.
To achieve the best results you should use this on a MIDI file with strictly monophonic channels; you should get an error message if a MIDI channel tries to play more than one note at the same time, though there is a "cheat mode" which forces a Note Off if a new Note On event is encountered while another note is still playing. Please note that I don't recommend to use that mode, though it will be needed to convert MIDI files which weren't prepared beforehand. Future versions *might* implement a "chord mode" where you can set a MIDI channel to spread on several YM2612 channels. Though I can't confirm this feature yet.
So yeah there's not much more to say now, this is an early beta just to see if it can gather some interest. Oh by the way the slider on the right sets the maximum volume achievable in the VGM file. Keep in mind that it's logarithmic so you DO NOT WANT to raise it too much.
Both Andlabs and TmEE gets tons of credit for their invaluable help. If it wasn't for them this converter wouldn't exist.
Obligatory sample files:
Unused S&KC song
Proof of concept of pitch bend
edit: this version should not be uploaded on the wiki, as it's an early proof of concept, likely to have dozens if not hundreds of bugs. I will give this a green light when I'll fell comfortable with that.