MIDI and Digital Audio

MIDI, the Musical Instrument Digital Interface, is a technical standard that lets electronic musical instruments, computers and related equipment communicate. Crucially, MIDI does not carry sound itself; instead it sends compact messages describing musical events, such as which note was pressed, how hard, and when it was released, along with control information for pitch bend, volume and patch changes. The receiving device, whether a synthesizer, sampler or software instrument, interprets these messages and generates the actual audio. This separation of performance data from sound is what makes MIDI so flexible.

Because the data is so compact, a piece of music represented as MIDI events can be stored in a tiny file compared with recorded audio. A standard MIDI file captures the timing and content of a performance, which can then be edited note by note, transposed, or played back on any compatible instrument, each potentially producing a different timbre. Sequencers and digital audio workstations use this to arrange, quantise and refine music, and MIDI controllers, such as keyboards, pad grids and knob banks, let a performer drive software instruments in real time.

MIDI is one part of a wider digital audio ecosystem. Where MIDI describes events, formats such as MP3 store the actual recorded sound as compressed audio, and metadata schemes like ID3 tags attach titles and artist information to those files. The do-it-yourself electronics community has long built custom MIDI controllers and interfaces, with projects such as the open MIDIbox platform allowing hobbyists to construct their own hardware. Together these technologies span the path from a performer's gesture to a finished audio recording.

Frequently asked questions

Does a MIDI file contain audio?

No. A MIDI file stores musical events such as notes, timing and control changes, not recorded sound. A synthesizer or software instrument turns those events into audio on playback.

Why are MIDI files so small?

They describe performances as compact event messages rather than storing waveform data, so a whole piece takes a tiny fraction of the space that recorded audio would need.

What is a MIDI controller?

It is a device such as a keyboard or pad array that sends MIDI messages to drive synthesizers or software instruments, letting a performer play and shape sound in real time.