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MIDI Objects for Python

Project description

Mido is a library for working with MIDI messages and ports. It’s designed to be as straight forward and Pythonic as possible:

>>> import mido
>>> output = mido.open_output()
>>> output.send(mido.Message('note_on', note=60, velocity=64))
>>> with mido.open_input('SH-201') as inport:
...     for msg in inport:
...         print(msg)
>>> from mido import Message
>>> msg = Message('program_change', program=1)
>>> msg
<message program_change channel=0 program=1 time=0>
>>> msg.copy(program=2, time=100)
<message program_change channel=0 program=2 time=100>
>>> msg.time
>>> msg.bytes()
[192, 1]
>>> from mido import MidiFile
>>> for msg in MidiFile('song.mid').play():
...     output.send(msg)

Full documentation at

Main Features

  • works in Python 2 and 3.
  • convenient message objects.
  • supports PortMidi, RtMidi and Pygame. New backends are easy to write.
  • full support for all 18 messages defined by the MIDI standard.
  • standard port API allows all kinds of input and output ports to be used interchangeably. New port types can be written by subclassing and overriding a few methods.s
  • includes a reusable MIDI parser.
  • full support for MIDI files (read, write, create and play) with complete access to every message in the file, including all common meta messages.
  • can read and write SYX files (binary and plain text).
  • implements (somewhat experimental) MIDI over TCP/IP with socket ports. This allows for example wireless MIDI between two computers.
  • includes programs for playing MIDI files, listing ports and serving and forwarding ports over a network.


1.1 is the second stable release.

See docs/changes.rst for a full list of changes.


Mido targets Python 2.7 and 3.2.

If you want to use message ports, you will need PortMidi installed on your system. The PortMidi library is loaded on demand, so you can use the parser and messages without it.

The PortMidi wrapper is tested on on Ubuntu and Mac OS X, but may also run on other systems where the file is available.

Alternative backends are included for python-rtmidi and Pygame. These can be selected with the environment variable MIDO_BACKEND or by calling mido.set_backend().

Like PortMidi, these are loaded on demand.


To install:

$ pip install mido

The PortMidi wrapper is written with ctypes, so no compilation is required.

If you want to use ports, you need the PortMidi shared library. The Ubuntu package is called libportmidi-dev, while the MacPorts and Homebrew packages are called portmidi.

To build documentation locally:

python docs

This requires Sphinx. The resulting files can be found in docs/_build/.

Known Bugs

  • in OS X, PortMidi and RtMidi usually hang for a second or two seconds while initializing. This is actually not a Mido bug, but something that happens at a lower level.

  • PortMidi in Ubuntu is mistakenly compiled in debug mode, which causes it to print out error message instead of returning an error code:

    PortMidi: `Bad pointer'
    type ENTER...PortMidi call failed...


    This means here is no way for Mido to catch the error and raise an exception.

    This regularity occurs in two places: in PortMidi when you close a port that has a callback, and in Pygame when you close any port.


Mido is released under the terms of the MIT license.


Ole Martin Bjorndalen -

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