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MIDI music audio file format
MIDI messages (along with timing information) can be collected and stored in a computer file system, in what is commonly called a MIDI file, or more formally, a Standard MIDI File (SMF). The SMF specification was developed maintained by the MIDI Manufacturers Association (MMA). MIDI files are typically created using computer-based sequencing software (or sometimes a hardware-based MIDI instrument or workstation) that organizes MIDI messages into one or more parallel "tracks" for independent recording and editing.
Large collections of SMFs can be found on the web, most commonly with the extension .mid; these files are most frequently authored with the assumption that they will be played on General MIDI players, but not always. Occasional unintended bad-sounding playback is the result.