MIDI Basics: Understanding Digital Music Notation
MIDI is not audio — it is a set of instructions that tells instruments what notes to play. Understanding this distinction unlocks powerful creative possibilities for music production, live performance, and sound design.
Key Takeaways
- MIDI (Musical Instrument Digital Interface) is a communication protocol from 1983 that remains the backbone of digital music production.
- Note numbers map to pitches: Middle C = 60, C#4 = 61, etc.
- Music production:** Compose in MIDI, experiment with different instruments and sounds after recording
- Released in 2020, MIDI 2.0 increases resolution from 7-bit (128 values) to 32-bit (4.3 billion values) for velocity, controllers, and pitch bend.
What MIDI Is
MIDI (Musical Instrument Digital Interface) is a communication protocol from 1983 that remains the backbone of digital music production. A MIDI file contains no sound — it contains instructions: 'play note C4 at velocity 80 for 500 milliseconds.' The receiving instrument (hardware synthesizer, software plugin, or virtual instrument) interprets these instructions and generates the actual sound.
MIDI Messages
Note Messages
| Message | Data | Purpose |
|---|---|---|
| Note On | Note number (0-127), Velocity (0-127) | Start playing a note |
| Note Off | Note number, Release velocity | Stop playing a note |
Note numbers map to pitches: Middle C = 60, C#4 = 61, etc. Velocity represents how hard the key was pressed (0 = silent, 127 = maximum force), which typically controls volume and tone.
Control Messages
- CC1 (Modulation): Typically vibrato depth
- CC7 (Volume): Channel volume
- CC10 (Pan): Left-right stereo position
- CC64 (Sustain): Sustain pedal on/off
- Pitch Bend: Smoothly bends pitch up or down
MIDI vs. Audio
| MIDI | Audio (WAV/MP3) |
|---|---|
| Instructions (what to play) | Actual sound waves |
| ~10 KB for a 4-min song | ~40 MB (WAV) / ~8 MB (MP3) |
| Editable note by note | Editable only as waveform |
| Sounds different on every instrument | Sounds identical everywhere |
| No fixed timbre/tone | Fixed timbre/tone |
Practical Uses
- Music production: Compose in MIDI, experiment with different instruments and sounds after recording
- Live performance: MIDI controllers (keyboards, drum pads) trigger sounds from laptops or hardware synths
- Education: MIDI visualizations show which notes are played (popular in YouTube piano tutorials)
- Film scoring: Compose with MIDI instruments, replace with live orchestra recordings later
MIDI 2.0
Released in 2020, MIDI 2.0 increases resolution from 7-bit (128 values) to 32-bit (4.3 billion values) for velocity, controllers, and pitch bend. This allows far more nuanced expression. Adoption is gradual — most software and hardware still uses MIDI 1.0.