| m15 | Soundtracker Music |
| m1a | MPEG Audio Layer 1 File |
| m22 | Farallon MacRecorder Recorded Audio |
| m2a | Mpeg-2 Audio |
| m2e | Yamaha Motif ES Multi Part Editor File |
| m3u | M3U Playlist File |
| m3u8 | M3U Playlist File |
| m4a | iTunes M4A Audio |
| 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 |
| ma | MusicAssembler Audio |
| mad | Mlat Adlib Tracker Music |
| mamx | Music Animation Machine Music |
| maud | Commodore Amiga IFF Audio |
| maxpat | Max Patch |
| mbnk | Miles Sound System 10 Audio Bank |
| mbnk_digest | Miles Sound System 10 Bank Digest Data |
| mcg | Compressed CD+G Karaoke File |
| mct | Musicator Music |
| mdi | MIDI Music |
| mdl | Digitrakker Music Module |
| mdx | Sharp X68000 Audio Data |
| med | OctaMED Music Module |
| mf3 | Ensoniq MR 76 Audio Data |
| mfb | Ensoniq MR 76 Audio Data |
