MIDIUtil is a pure Python library that allows one to write multi-track Musical Instrument Digital Interface (MIDI) files from within Python programs (both format 1 and format 2 files are now supported). It is object-oriented and allows one to create and write these files with a minimum of fuss.

MIDIUtil isn’t a full implementation of the MIDI specification. The actual specification is a large, sprawling document which has organically grown over the course of decades. I have selectively implemented some of the more useful and common aspects of the specification. The choices have been somewhat idiosyncratic; I largely implemented what I needed. When I decided that it could be of use to other people I fleshed it out a bit, but there are still things missing. Regardless, the code is fairly easy to understand and well structured. Additions can be made to the library by anyone with a good working knowledge of the MIDI file format and a good, working knowledge of Python. Documentation for extending the library is provided.

This software was originally developed with Python 2.5.2 and made use of some features that were introduced in 2.5. More recently Python 2 and 3 support has been unified, so the code should work in both environments. However, support for versions of Python previous to 2.7 has been dropped. Any mission-critical music generation systems should probably be updated to a version of Python supported and maintained by the Python foundation, lest society devolve into lawlessness.

This software is distributed under an Open Source license and you are free to use it as you see fit, provided that attribution is maintained. See License.txt in the source distribution for details.


he latest, stable version of MIDIUtil is hosted at the Python Package Index and can be installed via the normal channels:

pip install MIDIUtil

Source code is available on Github , and be cloned with one of the following URLS:

git clone git@github.com:MarkCWirt/MIDIUtil.git
# or
git clone https://github.com/MarkCWirt/MIDIUtil.git

depending on if you want to use SSH or HTTPS. (The source code for stable releases can also be downloaded from the Releases page.)

To use the library one can either install it on one’s system:

python setup.py install

or point your $PYTHONPATH environment variable to the directory containing midiutil (i.e., src).

MIDIUtil is pure Python and should work on any platform to which Python has been ported.

If you’re using this software in your own projects you may want to consider distributing the library bundled with yours; the library is small and self-contained, and such bundling makes things more convenient for your users. The best way of doing this is probably to copy the midiutil directory directly to your package directory and then refer to it with a fully qualified name. This will prevent it from conflicting with any version of the software that may be installed on the target system.

Quick Start

Using the software is easy:

  • The package must be imported into your namespace
  • A MIDIFile object is created
  • Events (notes, tempo-changes, etc.) are added to the object
  • The MIDI file is written to disk.

Detailed documentation is provided; what follows is a simple example to get you going quickly. In this example we’ll create a one track MIDI File, assign a tempo to the track, and write a C-Major scale. Then we write it to disk.

#!/usr/bin/env python

from midiutil import MIDIFile

degrees  = [60, 62, 64, 65, 67, 69, 71, 72] # MIDI note number
track    = 0
channel  = 0
time     = 0   # In beats
duration = 1   # In beats
tempo    = 60  # In BPM
volume   = 100 # 0-127, as per the MIDI standard

MyMIDI = MIDIFile(1) # One track, defaults to format 1 (tempo track
                     # automatically created)
MyMIDI.addTempo(track,time, tempo)

for pitch in degrees:
    MyMIDI.addNote(track, channel, pitch, time, duration, volume)
    time = time + 1

with open("major-scale.mid", "wb") as output_file:

There are several additional event types that can be added and there are various options available for creating the MIDIFile object, but the above is sufficient to begin using the library and creating note sequences.

The above code is found in machine-readable form in the examples directory. A detailed class reference and documentation describing how to extend the library is provided in the documentation directory.

Have fun!

Thank You

I’d like to mention the following people who have given feedback, bug fixes, and suggestions on the library:

  • Bram de Jong
  • Mike Reeves-McMillan
  • Egg Syntax
  • Nils Gey
  • Francis G.

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