A piece of software that can convert PSG VGM files into MIDI files. Vgm2Midi was developed to convert VGM (Video Game Music) files to standard MIDI files (to be used, for example, as a mobile 'phone ringtone).
The conversion is not perfect, and only supports PSG VGM files. I'm a bit of a newbie to the whole MIDI thing, but it all appears to work. I must warn you that the MIDI files outputted use the pitch wheel for fine-tuning (so MIDI synthesizers not supporting pitch wheel adjustments will no doubt sound horribly out of tune). The MIDI files also sound pretty ghastly with the softsynth that comes with Windows, but I can't really help that (after all, every MIDI file sounds pretty ghastly with the softsynth that comes with Windows).
MIDI synthesizers and the PSG are two very different systems, and as such you can't derive a MIDI file that sounds exactly like the original VGM file. One example is that instruments simulated by a MIDI synthesizer will have attack, sustain and decay effects. The PSG is limited to outputting square waves at fixed amplitudes, and so the author of the music for the PSG has to implement all these effects manually. Trying to convert these to MIDI sometimes adds surplus key events (so some attacks are duplicated within a short space of time - slow fades or vibrato effects are the worst culprits).
You can override these settings on the command-line. The command-line syntax is:
Vgm2Midi filename [-i i0 i1 i2 i3] [-p p0 p1 p2] [-a a440] [-s s0 s1 s2 s3] [-v v0 v1 v2 v3] [-l loop] [-f fadeout]
For example, to convert a file sonic.vgz and to use as percussive instruments a tambourine, a low tom and a set of maracas you would:
Vgm2Midi sonic.vgz -p 54 45 70
PRogram need NET Framework.
The license of this software is Freeware, you can free download and free use this audio converter software.