MIDI is a language that lets music gear and software talk to each other. It does not carry sound. It carries instructions: which note to play, how hard to play it, when to start and when to stop. A virtual instrument or a synth reads those instructions and makes the sound. The MIDI Association puts it simply: “MIDI is not audio.”
MIDI stands for Musical Instrument Digital Interface. It dates back to 1983, and it is still how keyboards, drum pads and DAWs share notes today.
MIDI vs audio
This is the part that confuses most beginners, so here it is side by side.
| MIDI | Audio | |
|---|---|---|
| What it stores | Instructions (note, velocity, timing) | The actual sound wave |
| Can you change a single note later? | Yes, easily | Only with special editing tools |
| Can you swap the instrument? | Yes: piano part becomes strings in one click | No, the sound is fixed |
| File size | Tiny | Large |
| Makes sound by itself? | No, it needs an instrument | Yes |
A good way to picture it: MIDI is sheet music, audio is a recording of someone playing that sheet music.
What a MIDI note contains
When you press a key on a MIDI keyboard, it sends a short message with a few pieces of information:
- Note number: which key. Notes run from 0 to 127, and middle C is note 60.
- Velocity: how hard you pressed, also from 0 to 127. Most instruments play louder or brighter at higher velocity.
- Note on and note off: when the note starts and when it stops, which gives its length.
- Channel: MIDI 1.0 has 16 channels on one connection, so one cable can control 16 different instruments.
There are also messages for things that are not notes, such as the sustain pedal, the pitch bend and mod wheels, and switching between sounds.
Where you see MIDI in a DAW
In a DAW, MIDI usually shows up in the piano roll: a grid with pitch running up and down and time running left to right. Each block is a note. You can drag it to change pitch, stretch it to change length, or change its velocity. If you are new to DAWs, start with what a DAW is.
The note you draw does not make sound until a virtual instrument plays it. Put the same MIDI part on a piano, then on a synth, then on strings, and you hear three different parts from one set of notes. Virtual instruments usually come as plugins; see what is a VST plugin.
What you can do with MIDI
- Fix mistakes after playing. Move a wrong note, tighten timing with quantize, or soften a note that is too loud.
- Write without playing. Draw notes with a mouse if you do not play keys.
- Change key or tempo freely. MIDI notes move to a new key or speed with no loss in quality, unlike audio.
- Layer sounds. Send one part to two instruments at once for a thicker sound.
- Control gear. Use knobs and faders on a controller to move settings in your DAW.
Do you need a MIDI keyboard?
No. You can draw every note in the piano roll with a mouse. A MIDI keyboard makes it faster to get ideas down and lets you play with feeling, because it records velocity. Most small controllers today connect with a single USB cable, which carries the MIDI data and often the power too. Older gear uses round 5-pin DIN MIDI cables, which carry MIDI only.
MIDI and chords
Because MIDI is just note numbers, a chord is simply several notes that start at the same time. If you are building chords in the piano roll and need the notes, our chord library shows the notes for 72 chords, and the Chord and Scale Finder covers the rest.
MIDI 2.0
A newer version, MIDI 2.0, adds finer detail, such as more steps for velocity and controllers and two-way communication between devices. MIDI 1.0 gear still works, and almost everything a beginner meets in a DAW behaves the way this guide describes.
Frequently asked questions
What does MIDI stand for?
Musical Instrument Digital Interface. It is a standard way for instruments, controllers and computers to send musical instructions to each other.
Is MIDI the same as audio?
No. MIDI carries instructions, like which note to play and how hard. Audio is the recorded sound itself. MIDI needs an instrument to turn it into sound.
Why does my MIDI track make no sound?
Usually because no instrument is loaded on the track, or the track is sending MIDI to an instrument that is muted. Load a virtual instrument on the track and check the volume.
Can I turn MIDI into audio?
Yes. Most DAWs call it “bounce”, “render” or “freeze”. The DAW plays the MIDI through the instrument and records the result as an audio file.
Ready to write your first MIDI part? Set your project tempo with the BPM Tapper, practise in time with the online metronome, and if you have not chosen a DAW yet, read the best DAW for beginners.
