"It is open source!
Here's a preview release of the N64 Midi Tool. It's an MFC DLL + Test Application. Note that the instruments files are coded to GoldenEye, and I don't know how many instruments are in the other games so you'll have to make your own, and import files for that. There's a sample lookup for GE, as thats the default, included with the zip.
It supports all the US known midi games, so good luck! The intent is for you to use it with your own programs and make your own midi instrument lookups. It also supports extract of midis (although instruments will be their usual #s, so not right), which should be interesting.
It will be posted on RWP soon as well, once it's out of alpha.
You are free to change, use any part of this code as long as you credit SubDrag and the RWP in your release, and you post here showing what you did.
The following games are believed to be supported:
GoldenEye;Perfect Dark;BanjoKazooie;BanjoTooie;Conker;Donkey Kong;Donkey Kong Demo;Jet Force Gemini;Blast Corps;Body Harvest;Cruisn World;Diddy Kong Racing;Diddy Kong Racing 1.1;Duke Nukem 64;Extreme G;Extreme G2;Jet Force Gemini Kiosk;Killer Instinct Gold;Killer Instinct Gold 1.2;Kirby 64;Mickeys Speedway USA;Razor Freestyle Scooter"