Creating MIDI Music Files using Python

MIDI, which stands for Musical Instrument Digital Interface, is a longstanding protocol for representing musical information in a digital format. It’s a powerful way to describe compositions, encompassing notes, durations, velocity, pitch, and many other musical nuances. With Python, one of the world’s most versatile programming languages, creating and manipulating MIDI files is both accessible and efficient. In this article, we will delve into how to create MIDI music files using Python.

A Brief Introduction to MIDI

MIDI is not sound by itself; it’s akin to a digital sheet music. It tells software or hardware what notes to play, how loud, how long, and with what instrument. When you listen to a MIDI file, you’re hearing software or hardware (like a digital piano or a synthesizer) interpret that “sheet music” and produce sound.

Key Concepts in MIDI

  • Tracks: MIDI compositions can consist of multiple tracks, similar to individual instruments in an orchestra.
  • Channels: Within tracks, there can be multiple channels, representing different instrumental parts.
  • Events: Actions in MIDI, like starting a note or changing an instrument, are called events.
  • Ticks: Ticks are the smallest unit of time in MIDI, representing the temporal resolution of events.

MIDI files function as sequences of messages that dictate how music should be played. These messages encompass everything from note pitches to durations, making the MIDI format rich and expressive. Given their structured nature, these sequences can be efficiently manipulated programmatically, allowing for intricate musical compositions and modifications.

The Python Landscape for MIDI

Python, being a versatile language, has multiple libraries for MIDI manipulation. For our journey, we’ll use mido and pretty_midi, two popular and effective libraries.

Setting up the Environment

Before diving into the code, ensure you have the required libraries:

pip install mido pretty_midi

Creating a Simple MIDI File with mido

Initializing a MIDI File

To create a MIDI file with mido, start by initializing it.

from mido import MidiFile, MidiTrack, Message

mid = MidiFile()
track = MidiTrack()

Adding Notes

Notes in MIDI are represented by two events: note_on (when the note starts) and note_off (when it ends). Each note also has a pitch (0-127) and a velocity (how hard it’s played, 0-127).

track.append(Message('note_on', note=60, velocity=64, time=0))    # C4 note start
track.append(Message('note_off', note=60, velocity=127, time=480)) # C4 note end after 480 ticks

Saving the MIDI File

Once your composition is ready, save it.'new_song.mid')

With this, you’ve created a simple MIDI file containing a single C4 note.

Crafting More Complex Compositions with pretty_midi

While mido is excellent for basic operations, pretty_midi offers higher-level functionalities, ideal for more intricate compositions.

Initializing a MIDI Composition

import pretty_midi

# Create a PrettyMIDI object
midi_composition = pretty_midi.PrettyMIDI()

Creating an Instrument Track

Here, we’ll add a piano track.

piano_program = pretty_midi.instrument_name_to_program('Acoustic Grand Piano')
piano = pretty_midi.Instrument(program=piano_program)

Adding Notes to the Instrument

note = pretty_midi.Note(velocity=100, pitch=60, start=0, end=0.5)  # C4 note from 0s to 0.5s

Appending the Instrument to the Composition and Saving


Tips for Effective MIDI Creation in Python

  1. Explore Other Instruments: MIDI supports a plethora of instruments. Don’t limit yourself to the piano; explore and add variety to your compositions.
  2. Manipulate Existing MIDI Files: Both mido and pretty_midi allow you to load existing MIDI files, edit them, and create something new.
  3. MIDI’s Versatility: MIDI is not limited to classical or standard music. It’s flexible. Experiment with unconventional sounds, rhythms, and structures.
  4. Understand Timing: MIDI timing can be intricate, especially with ‘ticks’. When working with durations and event placements, always account for the ticks and timings to ensure smooth musical flow.


Python, with its diverse libraries, offers a comprehensive environment for MIDI file creation. Whether you’re aiming for a simple melody or an elaborate composition, the Python ecosystem has got you covered. Dive in, explore, and let your musical creativity soar!

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