smps2xm

smps2xm in action

smps2xm is a program for Microsoft Windows created by Puto that converts songs from the SMPS (Sample Music Playback System) format to the XM (eXtended Module) format. Once the song is converted to XM, it can be easily edited with a tracker of choice (for example, Mod Plug Tracker or Fast Tracker II), and then converted again to SMPS with xm3smps.

Quick facts

smps2xm doesn't extract songs directly from roms, you have to split them up by yourself, and feed this converter with an individual binary file of the song you are willing to convert. Only Sonic 1's format is supported. If you need to convert a song from other SMPS games, you can use an utility like the Music Pointer Fixer to convert it to Sonic 1's format.
smps2xm won't set up the loop point in the XM file, it will read through the song for a certain number of SMPS time units, as each channel may happen to loop independently from the others. You can set up a loop point by hand in the resulting XM file.
smps2xm won't set up the instruments in the XM file. If you plan to actually listen to it, you'll have to fill in the instruments by hand.
smps2xm correctly reads almost all the SMPS coordination flags, though it's still possible for some songs to screw it up. If that's the case, some hex editing prior to the conversion may be required.