MIDI
Also known as: .mid file, MIDI file, Musical Instrument Digital Interface
MIDI is not recorded audio — it is a set of instructions describing which notes to play, how loud, and for how long. The device’s synthesizer turns those instructions into sound. Because no waveform is stored, MIDI files are tiny, often just a few kilobytes for a full song.
- Instructions to play notes, not recorded audio
- Tiny files — often a few kilobytes
- Cannot store vocals or live recordings
Instructions, not sound
Where MP3 or WAV store the actual sound wave, a MIDI file stores sheet-music-like commands: note on, note off, pitch, velocity, instrument. There is no audio in the file at all — the playback device generates the sound from a built-in instrument bank.
That is why MIDI is so small. A song that would be several megabytes as an MP3 can be a few kilobytes as MIDI, since you are saving directions instead of a recording.
What that means in practice
Because the sound is generated locally, the same MIDI file can sound different on different devices, and it cannot capture vocals or real-world recordings — only synthesized instruments. It is used in music production, notation software, and game audio.
To turn a MIDI file into something that plays consistently anywhere, you render it to a real audio format like MP3 or WAV.