During the past year, I wrote various converters that convert game music formats to MIDI.
They're listed in chronological order, source code is included.
The first one is seq2mid for PSFs.
.seq files are mostly MIDIs, but the tool makes you able to remap the instruments and fix a few things where SEQs behave differently from MIDIs.
Here are some example files. You'll need to look at the .ini-files, because I didn't document the instrument mapping format. (small note: columns are seperated by tabs, only the first number in a column is read)
This is the oldest one of the tools. The first version of it dates back to 2009 and was written in Visual Basic 6.
Note: You need to extract the SEQ and INS files manually from PSFs or the game itself. (Hint: The SEQ header starts with "pQES", and INS header with "pBAV".)
In 2010 I also worked on an akao2mid tool, but I'd need to work on it a bit before releasing it. Support for AKAO v1 (Final Fantasy 7) is pretty complete, AKAO v2 (FF8/9, Chrono Cross) needs some work.
Then we have smps2mid [direct link] (SMPS is used e.g. in Sonic games, see also the MD Sound Engine List)
and de2mid [direct link] (Data East's sound engine is used by many Chinese pirates), both written in 2011.
There's also [pack] Lem3DMid which I wrote in VB6 in early 2011 (it ran in the IDE only though) and ported it to C in 2012.
And finally, in 2012 I wrote:
- a small mod of de2mid to convert Sonic Spinball SMS songs to mid (I plan to add that to smps2mid)
- ffmq2mid (for the music format used by Square RPGs), this also need some work (but less than akao2mid) before I can release it
- sbm52mid (for Super Bomberman 5 SPCs, requested by Varion)
Note: does just a raw conversion with lots of debug output - top2mid (works also with Star Ocean) because I love SFC Tales of Phantasia's music
Note: The tool can remap instruments, but right now I've only hardcoded some of them. If anyone wants to makes an SPC->GM instrument list for ToP and SO I'll add instrument mapping support similar to seq2mid's. - and gems2mid (can also convert instruments and dump DAC sounds). I already ripped some data from GEMS games.
EDIT 2013-01-25: Added note about Sonic Spinball SMS tool.
EDIT 2013-04-24: Added link for Lem3DMid.
EDIT 2017-12-09: Changed gems2mid link to most recent version.