MIDI

The 1983 standard for talking between musical hardware and software — still the foundation of modern production.

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MIDI (Musical Instrument Digital Interface) was published in 1983, won the protocol war for hardware musical communication, and has been quietly underpinning every studio session since. The standard was updated to MIDI 2.0 in 2020.

It is not audio. MIDI is a series of instructions — "play this note, with this velocity, on this channel" — that a sound module then interprets to make audio.

What MIDI Carries

A note-on MIDI message specifies:

Note number — what pitch (0–127, where 60 is middle C).
Velocity — how hard the note was struck (0–127).
Channel — which of 16 channels the note belongs to.

MIDI also carries:

Note-off messages — when each note ends.
Continuous Controllers (CC) — modulation wheel, sustain pedal, expression, breath controller, etc.
Pitch bend — smoothly bending a note up or down.
Aftertouch — pressure applied after the initial keystrike.
Program change — switching presets on the receiving instrument.

Why It Matters

MIDI lets you separate what was played from how it sounds. A piano performance recorded as MIDI can be replayed through a different piano, an electric piano, a synth, or even a sampled choir. The notes don't change — the sound does.

This decoupling is the single most important workflow advantage of in-the-box production. You can change the bass synth on track 12 four hours into a mix without re-recording anything.

MIDI Channels and Routing

MIDI carries 16 channels. Historically, this let one MIDI cable control 16 different hardware instruments simultaneously. Today, in a DAW, channels are mostly used for splitting layers within a single multitimbral instrument (e.g., a layered orchestral patch with strings on ch.1, brass on ch.2, woodwinds on ch.3).

MIDI Editing in a DAW

Every DAW has a piano-roll editor that shows MIDI notes as horizontal bars. You can:

Quantise — snap notes to a rhythmic grid.
Velocity edit — change how hard each note plays.
Pitch edit — drag notes up or down.
Length edit — extend or shorten notes.
Humanise — add small random variations to make programmed parts feel less robotic.

MPE (MIDI Polyphonic Expression)

A 2018 extension to MIDI 1.0 that lets each note carry its own pitch bend, aftertouch, and modulation. The result: expressive playing on instruments like the ROLI Seaboard, LinnStrument, or Roli Lumi. Each finger can bend, slide, and add vibrato independently.

Most modern DAWs and many soft-synths support MPE. If you have an MPE controller, your synth needs to support MPE explicitly.

MIDI 2.0

The 2020 update adds:

Higher resolution — 32-bit data instead of 7-bit (so 4 billion values per parameter instead of 128).
Bidirectional communication — devices can interrogate each other.
Profiles — standardised feature sets so devices interoperate more reliably.

Adoption is still rolling out. Most current hardware and software is still MIDI 1.0, with MIDI 2.0 features creeping in as new products release.

Common Mistakes

Over-quantising. Snapping every note to the grid removes the human feel. Modern producers often quantise to 80–95% strength, leaving small natural fluctuations.

Forgetting MIDI velocity. A flat velocity curve (every note at 100) sounds robotic. Even on programmed parts, varying velocity makes a huge difference.

Routing confusion. Two MIDI tracks both routed to the same instrument can double-trigger notes. If your track sounds twice as loud as expected, check routing first.

Treating MIDI like audio. MIDI doesn't carry sound. If a track is silent, the instrument might be missing, the channel might be wrong, or a note might be outside the instrument's range — none of which an audio waveform editor will help with.