| m2e | Yamaha Motif ES Multi Part Editor File |
| m3u | M3U Playlist File |
| m3u8 | M3U Playlist File |
| m4a | Mpeg-4 Audio |
| m4b | Mpeg-4 Audio Book |
| m4e | Yamaha Motif ES Multi Part Editor File |
| m4p | DRM Protected AAC File |
| m4r | iPhone Ringtone |
| m5m | MachFive Audio Data |
| m7a | Yamaha MO8 Internal User Memory Data |
| mamx | Music Animation Machine Music |
| maud | Commodore Amiga IFF Audio |
| maxpat | Max Patch |
| mcg | Compressed CD+G Karaoke File |
| mct | Musicator Music |
| mdi | MIDI Music |
| med | OctaMED Music Module |
| mf3 | Ensoniq MR 76 Audio Data |
| mfb | Ensoniq MR 76 Audio Data |
| mg1 | Band-in-a-Box Song |
| mg2 | Band-in-a-Box Song |
| mg3 | Band-in-a-Box Song |
| mg4 | Band-in-a-Box Song |
| mg5 | Band-in-a-Box Song |
| mg6 | Band-in-a-Box Song |
| mg7 | Band-in-a-Box Song |
| mg8 | Band-in-a-Box Song |
| mg9 | Band-in-a-Box Song |
| mgb | Paragon 5 Gameboy Tracker Audio |
| mgu | Band-in-a-Box Song |
| mgv | Yamaha MegaVoice Audio |
| mia | MusicIndiaOnline Trident Player Music |
| mid | MIDI Music |
| midi | MIDI Music |
| minigsf | Game Boy Advance GSF Song |