What Is a MIDI File? A Pianist's and Producer's Guide

If you have ever downloaded a song as a .mid file, plugged a digital piano into a computer, or exported a transcription from an app, you have used MIDI. It is one of the oldest and most widely supported standards in music technology, and it still sits at the center of how pianists, producers and composers work.

This guide explains what a MIDI file actually contains, what it does not contain, and how to use it well.

A short history: where MIDI comes from

MIDI stands for Musical Instrument Digital Interface. It was created so that electronic instruments from different manufacturers could talk to each other.

According to the MIDI Association's history of MIDI, the first public demonstration took place at the Winter NAMM show in Anaheim on 21 to 23 January 1983, between a Sequential Circuits Prophet 600 and a Roland Jupiter 6. The same history says Sequential began shipping the Prophet-600, the first commercially available instrument with MIDI, in December 1983.

The standard has kept evolving. The MIDI Association's MIDI 2.0 timeline says the core MIDI 2.0 specifications were adopted by AMEI and the MIDI Association in January 2020. For everyday file exchange, though, the classic Standard MIDI File is still what you will encounter almost everywhere.

MIDI is not audio

This is the single most important idea. As the MIDI Association puts it in its MIDI overview, MIDI is not audio.

An MP3 or WAV file is a recording of sound waves. A MIDI file is closer to a player piano roll: a list of events that tell an instrument what to do. The MIDI Association describes Standard MIDI Files as a list of events that a playback device uses to generate sound.

That difference has practical consequences:

What is inside a MIDI file

A Standard MIDI File is built from MIDI messages with timestamps. For a pianist, a handful of message types do almost all the work.

Note On and Note Off

When you press a key on a MIDI keyboard, it sends a Note On message, and when you release it, a Note Off message. Per the MIDI Association's guide to MIDI messages, the Note On message carries a key number and a velocity, meaning how hard the key was pressed.

Note numbers

In the MIDI Association's list of MIDI 1.0 messages, Note On and Note Off carry a note number from 0 to 127. Middle C is conventionally note 60. One confusing detail: software disagrees on what to call it. A thread on the MIDI Association's forum about octave numbering shows users arguing for C3, C4 and C5, which is a naming choice in each program, not part of the note number. If your notes appear an octave off when you move a file between programs, this is a likely reason.

Velocity

Velocity values run from 0 to 127, and the MIDI Association describes velocity as how hard the key was pressed, which determines how loud the note plays relative to others. This is how a MIDI file preserves the dynamics of a performance, even though it contains no sound.

Control Change messages, including the pedals

Control Change (CC) messages handle everything that is not a note. For pianists, the pedals matter most. The MIDI Association's Control Change table lists:

Channels, tracks and tempo

MIDI 1.0 has 16 channels, which let one connection carry several instrument parts at once. According to the MIDI Association, a Standard MIDI File also has header data such as tempo and instrument choices per channel, plus song information such as copyright and composer.

Type 0 vs. Type 1 MIDI files

The MIDI Association explains that there are two common varieties:

• Type 0: everything is merged into a single track. It is the simplest structure, handy for devices and apps that expect a single track.
• Type 1: individual parts are saved on separate tracks. This is usually more convenient for editing, for example with the right hand and left hand, or piano and strings, on different tracks.

A Type 2 format was also specified but rarely used. When a program asks which type to export, choose Type 1 unless you know the receiving device needs Type 0.

How pianists use MIDI files

Recording practice sessions. If you play a digital piano, you can often record MIDI directly: the MIDI Association notes that many digital pianos can create and play Standard MIDI Files, so check your model's manual. You capture every note and velocity with no microphone noise at all.

Turning performances into sheet music. A MIDI file is a great intermediate step toward notation. Free software such as MuseScore Studio can open MIDI files, according to its handbook, though the handbook's own page on working with MIDI is an unwritten placeholder and we have not tested its import here. A MusicXML file usually gets you a better first draft, because it carries the notation choices. If you only have an audio recording, a converter can generate the MIDI and the MusicXML for you: our transcription tool does both, and our guide on converting a piano recording to sheet music covers the workflow.

Learning pieces. Piano-roll and "falling notes" learning apps typically read MIDI. Slowing down a MIDI file never changes its pitch or adds audio artifacts.

Checking your own transcription. Play a MIDI file back next to the original recording and wrong notes jump out immediately.

How producers use MIDI files

Swapping sounds. Record a part once, then try it with a concert grand, an upright, an electric piano or a pad, without re-recording.

Fixing performances. Move a rushed note, lower a harsh velocity, or quantize a section to the grid, while leaving the rest of the human feel intact.

Layering and arranging. Copy a piano voicing to strings, or double a bass line with a synth.

Sharing ideas. MIDI files are tiny, and every major DAW opens them, which makes them easy to send to collaborators.

MIDI vs. MusicXML: which one do you need?

Both files can come out of a transcription, and they are often confused.

• MIDI answers "what was played": exact timings, velocities and pedal. It is ideal for DAWs, playback and performance editing.
• MusicXML answers "how should it be written": clefs, measures, note spelling (C sharp vs. D flat), beaming, ties and layout. It is an open format maintained by the W3C Music Notation Community Group and is the right choice for exchanging sheet music between notation programs.

If your goal is a score you will read at the piano, open the MusicXML. If your goal is a production or a playback file, use the MIDI.

Where MIDI from audio falls short

When MIDI is created by converting an audio recording rather than captured from a digital piano, it is an estimate of what was played. Expect some issues:

• Dense chords can lose inner notes or gain extra ones.
• Sustain pedal can blur where notes end, so note lengths are the least reliable part.
• Overtones and resonating strings can be picked up as extra notes.
• Other instruments in the recording can create many false notes.

Clean solo piano recordings reduce these problems significantly. Our guide on recording piano with your phone shows how to get a clean take. If you are weighing different conversion tools, see our audio to MIDI converter comparison.

Frequently asked questions

Does a MIDI file contain sound?

No. A MIDI file contains instructions such as which note to play, when, and how hard. The sound you hear comes from whatever instrument or software plays those instructions back, which is why the same file can sound very different on two devices.

Is MIDI the same as sheet music?

No. MIDI stores performance data (note numbers, timing and velocity) but not notation details like clefs, note spelling, beaming or fingering. Notation programs can open MIDI and turn it into a score, but MusicXML is the better format for exchanging actual sheet music.

Can I open a MIDI file on my phone or computer?

Yes. The MIDI Association lists DAWs such as GarageBand, Logic, Ableton Live, FL Studio and Cubase among the software that can play Standard MIDI Files, and MuseScore Studio's handbook says it can open MIDI files. Its MIDI import options are thin, though, so for a score prefer MusicXML.

What is the difference between MIDI Type 0 and Type 1?

According to the MIDI Association, a Type 0 file merges everything into a single track, while a Type 1 file keeps individual parts on separate tracks. Type 1 is usually more convenient for editing, while Type 0 suits devices that expect a single track.

Why does my MIDI file sound robotic?

Either the notes were entered with perfectly even timing and velocity, or the sound playing them back is a basic synthesizer. Try a better piano virtual instrument, and add small variations in velocity and timing.

Sources

Pages read on 19 September 2026.

• MIDI Association: MIDI History Chapter 6, MIDI begins 1981-1983 (the January 1983 demonstration, Prophet-600 shipping)
• MIDI Association: Detailed timeline of MIDI 2.0 developments (core specifications adopted January 2020)
• MIDI Association: About MIDI part 1, overview ("MIDI is not audio")
• MIDI Association: About MIDI part 3, MIDI messages (Note On, velocity, 16 channels) and Expanded MIDI 1.0 messages list (note numbers 0 to 127)
• MIDI Association forum: MIDI octave and note numbering (a user thread, cited only for the C3/C4/C5 naming disagreement)
• MIDI 1.0 Control Change messages (CC 7, 11, 64, 66, 67)
• MIDI Association: About MIDI part 4, MIDI files (event lists, Type 0 and Type 1, header data, DAWs and digital pianos)
• General MIDI Level 1
• MuseScore Studio handbook: Opening and saving scores and Working with MIDI (the placeholder page)
• W3C Music Notation Community Group: MusicXML 4.0