What is MIDI and What Can I do with It?

What is MIDI?

MIDI stands for Musical Instrument Digital Interface and is the standard communication protocol for instruments that interface with a computer. It was established in 1983 by music industry representatives and is updated by the MIDI Manufacturers Organization. MIDI commands include instruction for how to trigger and alter sounds, never the sounds themselves (MIDI represents a note, not digital audio). For example, a MIDI command may send a note on command for a specific pitch (like C#4), a duration, a velocity, then a note off command. The computer or MIDI instrument receives these commands and triggers the specified key (playing whatever sound it’s mapped to) at the specified duration and velocity. MIDI also made it possible to share and distribute music with very small file sizes.

MIDI ports on a Rooland synth.

MIDI ports on the back of a Roland Alpha Juno synthesizer.

MIDI was created so you could use one instrument to trigger others (keyboards, synths, and sound modules). A while later, General MIDI was created so everyone could use the same set of instruments with no remapping; it was updated once and competitors took their shot at MIDI instrument sets and banks over the years. Now, MIDI is used within a DAW to trigger thousands of highly complex software instruments; the process of creating and editing MIDI data to trigger audio is called “sequencing.” Besides in music, MIDI can trigger lighting effects, firework explosion timings (in mid-air), cue clips, synchronize equipment, play automation, and anything else configured to receive MIDI commands.

A standard, 5-pin DIN MIDI cable.

Some devices still use the 5-pin DIN connector, but most controllers have migrated to USB

Since MIDI data is easy to create, edit, and copy around, it has fundamentally altered the composition process for most of the industry. For example, a single keyboard can now control any instrument, without any additional hardware. With a single operation, a song’s MIDI data can change key, be randomized, etc . . . It can also be exported into a notation program, flipping the progression of sheet music to DAW.

MIDI data can be sent from a single device to any combination of up to 16 channels. This is commonly specified within a DAW to facilitate workflow and streamline resource use. it also allows performers to control multiple instruments simultaneously with a single controller, even if they’re daisy-chained together. Each instrument only accepts MIDI data that’s tagged with its channel number.

Now, on to the instruments . . .

Resources for this Section

MIDI.org is the official, free, non-profit organization that exists to promote the MIDI protocol. The site hosts expo info., forums, articles, courses, and more.