SMPS
From Sega Retro
The Sample Music Playback System is a sound engine used in several games for the Sega Mega Drive/Genesis and the Sega 32X, including all the major Sonic games except Sonic Spinball, which uses GEMS instead. A few versions of this engine exist; most notably, both a 68K and a Z80 version were developed. It is possible to port songs between two games that uses the SMPS engine; however, several games use a slightly different revision of the format, and the chance that the ported song will need extensive editings by hand (usually with an hex editor) is very high.
Many sceners have been working on the SMPS format, doing an extensive work of research. Most credit should be given to Saxman, the man who started it all, but a lot of hackers continued his work up to our days, including Puto and Tweaker.
We now have a quite complete knowledge of this format, and several tools are available to hackers who want to tweak the music in their hacks. In particular, the xm3smps tool, created by nineko, allows music to be imported into the SMPS format with ease, generally having very favorable results.
It should be noted that both GYM and VGM files are logs of the data sent to the sound chipset rather than a dump of the sound data itself.
See also
- A very comprehensive guide detailing the SMPS format; mainly focused to Sonic games, though it contains a few resources for other games as well.