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IMF (probably) stands for "ID Software Music Format" and is remarkably similar to the Rdos RAW file format. It contains a list of the data bytes to be sent to the OPL chip on an Adlib or SoundBlaster sound card, as well as how long a delay should be left between sending the bytes.

The end result is a very lightweight music player, which uses very little CPU time - essential in the days when games were required to run smoothly on a 286.

Most of the early id/Apogee games used this format for music, including Cosmo's Cosmic Adventures, Duke Nukem II, Wolfenstein 3D, Bio Menace and many others.

A complete technical description of the format can be found in the ModdingWiki article on the IMF Format.


  • IMF2MIDI can be used to convert IMF files into MIDI files


  • Adlib-XMMS - a free Adlib player that will play IMF, CMF and DRO files, amongst others (XMMS plug-in source code available)
  • AdPlug - a free Adlib player that will play IMF files (DOS, Winamp and XMMS versions available)
  • Wikipedia:IMF_(music) - Wikipedia article on the IMF format
  • ModdingWiki:IMF Format - technical documentation