Mido - MIDI Objects for Python

Version 1.1.24

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
100
>>> msg.bytes()
[192, 1]

>>> from mido import MidiFile
>>> for msg in MidiFile('song.mid').play():
...     output.send(msg)

Mido is short for MIDi Objects.

Source code

https://github.com/olemb/mido/

About This Document

This document is available at https://mido.readthedocs.io/

To build locally:

python setup.py docs

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

Contents

Changes

Release History

1.1.24 (2017-02-16)

• bugfix: PortMidi backend was broken on macOS due to a typo. (Fix by Sylvain Le Groux, pull request #81.)

1.1.23 (2017-01-31)

• bugfix: read_syx_file() didn’t handle ‘n’ in text format file causing it to crash. (Reported by Paul Forgey, issue #80.)

1.1.22 (2017-01-27)

• the bugfix in 1.1.20 broke blocking receive() for RtMidi. Reverting the changes. This will need some more investigation.

1.1.21 (2017-01-26)

• bugfix: MidiFile save was broken in 1.1.20 due to a missing import.

1.1.20 (2017-01-26)

• bugfix: close() would sometimes hang for RtMidi input ports. (The bug was introduced in 1.1.18 when the backend was rewritten to support true blocking.)

• Numpy numbers can now be used for all message attributes. (Based on implementation by Henry Mao, pull request #78.)

  The code checks against numbers.Integral and numbers.Real (for the time attribute) so values can be any subclass of these.

1.1.19 (2017-01-25)

• Pygame backend can now receive sysex messages. (Fix by Box of Stops.)
• bugfix: libportmidi.dylib was not found when using MacPorts. (Fix by yam655, issue #77.)
• bugfix: SocketPort.__init() was not calling IOPort.__init__() which means it didn’t get a self._lock. (Fixed by K Lars Lohn, pull request #72. Also reported by John J. Foerch, issue #79.)
• fixed typo in intro example (README and index.rst). Fix by Antonio Ospite (pull request #70), James McDermott (pull request #73) and Zdravko Bozakov (pull request #74).
• fixed typo in virtual ports example (Zdravko Bozakov, pull request #75.)

1.1.18 (2016-10-22)

• time is included in message comparison. msg1 == msg2 will now give the same result as str(msg1) == str(msg2) and repr(msg1) == repr(msg2).

  This means you can now compare tracks wihout any trickery, for example: mid1.tracks == mid2.tracks.

  If you need to leave out time the easiest was is msg1.bytes() == msg2.bytes().

  This may in rare cases break code.

• bugfix: end_of_track messages in MIDI files were not handled correctly. (Reported by Colin Raffel, issue #62).

• bugfix: merge_tracks() dropped messages after the first end_of_track message. The new implementation removes all end_of_track messages and adds one at the end, making sure to adjust the delta times of the remaining messages.

• refactored MIDI file code.

• mido-play now has a new option -m / --print-messages which prints messages as they are played back.

• renamed parser._parsed_messages to parser.messages. BaseInput and SocketPort use it so it should be public.

• Parser() now takes an option arugment data which is passed to feed().

1.1.17 (2016-10-06)

• RtMidi now supports true blocking receive() in Python 3. This should result in better performance and lower latency. (Thanks to Adam Roberts for helping research queue behavior. See issue #49 for more.)
• bugfix: MidiTrack.copy() (Python 3 only) returned list.
• fixed example queue_port.py which broke when locks where added.

1.1.16 (2016-09-27)

• bugfix: MidiTrack crashed instead of returning a message on track[index]. Fix by Colin Raffel (pull request #61).

• added __add__() and __mul__() to MidiTrack so + and * will return tracks instead of lists.

• added poll() method to input ports as a shortcut for receive(block=False).

• added example rtmidi_python_backend.py, a backend for the rtmidi-python package (which is different from the python-rtmidi backend that Mido currently uses.) This may at some point be added to the package but for now it’s in the examples folder. (Requested by netchose, issue #55.)

• removed custom _import_module(). Its only function was to make import errors more informative by showing the full module path, such as ImportError: mido.backends.rtmidi instead of just ImportError: rtmidi. Unfortunately it ended up masking import errors in the backend module, causing confusion.

  It turns importlib.import_module() can be called with the full path, and on Python 3 it will also display the full path in the ImportError message.

1.1.15 (2016-08-24)

• Sending and receiving messages is now thread safe. (Initial implementation by Adam Roberts.)

• Bugfix: PortServer called __init__ from the wrong class. (Fix by Nathan Hurst.)

• Changes to MidiTrack:

  • MidiTrack() now takes a as a parameter an iterable of messages. Examples:

    MidiTrack(messages)
    MidiTrack(port.iter_pending())
    MidiTrack(msg for msg in some_generator)
    

  • Slicing a MidiTrack returns a MidiTrack. (It used to return a list.) Example:

    track[1:10]
    

• Added the ability to use file objects as well as filenames when reading, writing and saving MIDI files. This allows you to create a MIDI file dynamically, possibly not using mido, save it to an io.BytesIO, and then play that in-memory file, without having to create an intermediate external file. Of course the memory file (and/or the MidiFile) can still be saved to an external file. (Implemented by Brian O’Neill.)

• PortMidi backend now uses pm.lib.Pm_GetHostErrorText() to get host error messages instead of just the generic “PortMidi: `Host error’”. (Implemented by Tom Manderson.)

Thanks to Richard Vogl and Tim Cook for reporting errors in the docs.

1.1.14 (2015-06-09)

• bugfix: merge_tracks() concatenated the tracks instead of merging them. This caused tracks to be played back one by one. (Issue #28, reported by Charles Gillingham.)

• added support for running status when writing MIDI files. (Implemented by John Benediktsson.)

• rewrote the callback system in response to issues #23 and #25.

• there was no way to set a callback function if the port was opened without one. (Issue#25, reported by Nils Werner.)

  Callbacks can now be set and cleared at any time by either passing one to open_input() or updating the callback attribute.

  This causes some slight changes to the behavior of the port when using callbacks. Previously if you opened the port with a callback and then set port.callback = None the callback thread would keep running but drop any incoming messages. If you do the same now the callback thread will stop and the port will return normal non-callback behavior. If you want the callback thread to drop messages you can set port.callback = lambda message: None.

  Also, receive() no longer checks self.callback. This was inconsistent as it was the only method to do so. It also allows ports that don’t support callbacks to omit the callback attribute.

• bugfix: closing a port would sometimes cause a segfault when using callbacks. (Issue #24, reported by Francesco Ceruti.)

• bugfix: Pygame ports were broken due to a faulty check for virtual=True.

• now raises ValueError instead of IOError if you pass virtual or callback while opening a port and the backend doesn’t support them. (An unsupported argument is not an IO error.)

• fixed some errors in backend documentation. (Pull request #23 by velolala.)

• MultiPort now has a yield_port argument just like multi_receive().

1.1.13 (2015-02-07)

• the PortMidi backend will now return refresh the port list when you ask for port names are open a new port, which means you will see devices that you plug in after loading the backend. (Due to limitations in PortMidi the list will only be refreshed if there are no open ports.)
• bugfix: tempo2bpm() was broken and returned the wrong value for anything but 500000 microseconds per beat (120 BPM). (Reported and fixed by Jorge Herrera, issue #21)
• bugfix: merge_tracks() didn’t work with empty list of tracks.
• added proper keyword arguments and doc strings to open functions.

1.1.12 (2014-12-02)

• raises IOError if you try to open a virtual port with PortMidi or Pygame. (They are not supported by these backends.)
• added merge_tracks().
• removed undocumented method MidiFile.get_messages(). (Replaced by merge_tracks(mid.tracks).)
• bugfix: receive() checked self.callback which didn’t exist for all ports, causing an AttributeError.

1.1.11 (2014-10-15)

• added bpm2tempo() and tempo2bpm().
• fixed error in documentation (patch by Michael Silver).
• added notes about channel numbers to documentation (reported by ludwig404 / leonh, issue #18).

1.1.10 (2014-10-09)

• bugfix: MidiFile.length was computer incorrectly.
• bugfix: tempo changes caused timing problems in MIDI file playback. (Reported by Michelle Thompson.)
• mido-ports now prints port names in single ticks.
• MidiFile.__iter__() now yields end_of_track. This means playback will end there instead of at the preceding message.

1.1.9 (2014-10-06)

• bugfix: _compute_tick_time() was not renamed to _compute_seconds_per_tick() everywhere.
• bugfix: sleep time in play() was sometimes negative.

1.1.8 (2014-09-29)

• bugfix: timing in MIDI playback was broken from 1.1.7 on. Current time was subtracted before time stamps were converted from ticks to seconds, leading to absurdly large delta times. (Reported by Michelle Thompson.)
• bugfix: read_syx_file() didn’t handle empty file.

1.1.7 (2014-08-12)

• some classes and functions have been moved to more accessible locations:

  from mido import MidiFile, MidiTrack, MetaMessage
  from mido.midifiles import MetaSpec, add_meta_spec
  

• you can now iterate over a MIDI file. This will generate all MIDI messages in playback order. The time attribute of each message is the number of seconds since the last message or the start of the file. (Based on suggestion by trushkin in issue #16.)

• added get_sleep_time() to complement set_sleep_time().

• the Backend object no longer looks for the backend module exists on startup, but will instead just import the module when you call one of the open_*() or get_*() functions. This test didn’t work when the library was packaged in a zip file or executable.

  This means that Mido can now be installed as Python egg and frozen with tools like PyInstaller and py2exe. See “Freezing Mido Programs” for more on this.

  (Issue #17 reported by edauenhauer and issue #14 reported by netchose.)

• switched to pytest for unit tests.

1.1.6 (2014-06-21)

• bugfix: package didn’t work with easy_install. (Issue #14, reported by netchose.)
• bugfix: 100% memory consumption when calling blocking receive() on a PortMidi input. (Issue #15, reported by Francesco Ceruti.)
• added wheel support: http://pythonwheels.com/

1.1.5 (2014-04-18)

• removed the ‘mode’ attribute from key_signature messages. Minor keys now have an ‘m’ appended, for example ‘Cm’.
• bugfix: sysex was broken in MIDI files.
• bugfix: didn’t handle MIDI files without track headers.
• bugfix: MIDI files didn’t handle channel prefix > 15
• bugfix: MIDI files didn’t handle SMPTE offset with frames > 29

1.1.4 (2014-10-04)

• bugfix: files with key signatures Cb, Db and Gb failed due to faulty error handling.
• bugfix: when reading some MIDI files Mido crashed with the message “ValueError: attribute must be in range 0..255”. The reason was that Meta messages set running status, which caused the next statusless message to be falsely interpreted as a meta message. (Reported by Domino Marama).
• fixed a typo in MidiFile._read_track(). Sysex continuation should work now.
• rewrote tests to make them more readable.

1.1.3 (2013-10-14)

• messages are now copied on send. This allows the sender to modify the message and send it to another port while the two ports receive their own personal copies that they can modify without any side effects.

1.1.2 (2013-10-05)

• bugfix: non-ASCII character caused trouble with installation when LC_ALL=C. (Reported by Gene De Lisa)
• bugfix: used old exception handling syntax in rtmidi backend which broke in 3.3
• fixed broken link in

1.1.1 (2013-10-04)

• bugfix: mido.backends package was not included in distribution.

1.1.0 (2013-10-01)

• added support for selectable backends (with MIDO_BACKEND) and included python-rtmidi and pygame backends in the official library (as mido.backend.rtmidi and mido.backend.pygame).
• added full support for MIDI files (read, write playback)
• added MIDI over TCP/IP (socket ports)
• added utility programs mido-play, mido-ports, mido-serve and mido-forward.
• added support for SMPTE time code quarter frames.
• port constructors and open_*() functions can now take keyword arguments.
• output ports now have reset() and panic() methods.
• new environment variables MIDO_DEFAULT_INPUT, MIDO_DEFAULT_OUTPUT and MIDO_DEFAULT_IOPORT. If these are set, the open_*() functions will use them instead of the backend’s default ports.
• added new meta ports MultiPort and EchoPort.
• added new examples and updated the old ones.
• format_as_string() now takes an include_time argument (defaults to True) so you can leave out the time attribute.
• sleep time inside sockets can now be changed.
• Message() no longer accepts a status byte as its first argument. (This was only meant to be used internally.)
• added callbacks for input ports (PortMidi and python-rtmidi)
• PortMidi and pygame input ports now actually block on the device instead of polling and waiting.
• removed commas from repr() format of Message and MetaMessage to make them more consistent with other classes.

1.0.4 (2013-08-15)

• rewrote parser

1.0.3 (2013-07-12)

• bugfix: __exit__() didn’t close port.
• changed repr format of message to start with “message”.
• removed support for undefined messages. (0xf4, 0xf5, 0xf7, 0xf9 and 0xfd.)
• default value of velocity is now 64 (0x40). (This is the recommended default for devices that don’t support velocity.)

1.0.2 (2013-07-31)

• fixed some errors in the documentation.

1.0.1 (2013-07-31)

• multi_receive() and multi_iter_pending() had wrong implementation. They were supposed to yield only messages by default.

1.0.0 (2013-07-20)

Initial release.

Basic functionality: messages, ports and parser.

Installing Mido

Requirements

Mido targets Python 2.7 and 3.2. It is developed and tested in Ubuntu and Mac OS X, but should also work in Windows.

Everything is implemented in pure Python, so no compilation is required.

There are no external dependencies unless you want to use the port backends, which are loaded on demand.

Mido comes with backends for PortMidi, python-rtmidi and Pygame.

Installing

To install:

$ pip install mido

Installing PortMidi (Optional)

PortMidi is available in Ubuntu as libportmidi-dev and in MacPorts and Homebrew as portmidi.

Installing python-rtmidi (Optional)

python-rtmidi requires librtmidi.so, which is available in Ubuntu as librtmidi-dev (and possible also available as a package in MacPorts and Homebrew.

Ideally this should work:

$ pip install python-rtmidi

but the package appears to be broken in PyPI. To get around this you can do:

$ pip install --pre python-rtmidi

The --pre is because pip refuses to install when the library looks like a pre-release, and says: “Could not find a version that satisfies the requirement XYZ.”)

Contributing

Testing

pytest is used for unit testing. The tests are found in mido/test_*.py.

If you can please run tests in both Python 2 and Python 3 before you commit code. I’ve renamed the executables so I can just run pytest2 && pytest3 instead of remembering what the programs are called. (I think they were py.test and py.test-3.)

You can also set up a commit hook:

echo "pytest2 && pytest3" >.git/hooks/pre-commit
chmod +x .git/hooks/pre-commit

This will run tests when you commit and cancel the commit if any tests fail.

Testing MIDI file support

Test Files

The Lakh MIDI Dataset is a great resouce for testing the MIDI file parser.

Publishing (Release Checklist)

I am currently the only one with access to publishing on PyPI and readthedocs. This will hopefully change in the future.

First Time: Register With PyPI

./setup.py register

Test

rm -rf docs/_build && ./setup.py docs
pytest2 && pytest3
check-manifest -v

(pip3 install check-manifest)

You can also test that the package installs by installing it in a virtualenv with pip and easy_install (Python 2 and 3) and importing it. This is a bit tedious. Perhaps there is a good way to automate it.

Bump Version

X.Y.Z is the version, for example 1.1.18 or 1.2.0.

• update version and date in docs/changes.rst
• update version in mido/__init__.py
• git commit -a -c “Bumped version to X.Y.Z.”

Then:

git tag X.Y.Z
git push
git push --tags

Publish

This has stopped working recently (late 2016) so instead I just go to the web page and upload from there.

Publish in PyPI:

python setup.py publish
python setup.py bdist_wheel upload

Last thing:

Update readthedocs

Introduction (Basic Concepts)

Mido is all about messages and ports.

Messages

Mido allows you to work with MIDI messages as Python objects. To create a new message:

>>> from mido import Message
>>> msg = Message('note_on', note=60)
>>> msg
<message note_on channel=0 note=60 velocity=64 time=0>

Note

Mido numbers channels 0 to 15 instead of 1 to 16. This makes them easier to work with in Python but you may want to add and subtract 1 when communicating with the user.

A list of all supported message types and their parameters can be found in Message Types.

The values can now be accessed as attributes:

>>> msg.type
'note_on'
>>> msg.note
60
>>> msg.velocity
64

Attributes are also settable but this should be avoided. It’s better to use msg.copy():

>>> msg.copy(note=100, velocity=127)
<message note_on channel=2 note=100 velocity=127 time=0)

Type and value checks are done when you pass parameters or assign to attributes, and the appropriate exceptions are raised. This ensures that the message is always valid.

For more about messages, see Messages.

Type and Value Checking

Mido messages come with type and value checking built in. This happens when you assign an out of range value to an attribute:

>>> n = mido.Message('note_on')
>>> n.channel = 2092389483249829834
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "./mido/messages.py", line 327, in __setattr__
    ret = check(value)
  File "./mido/messages.py", line 128, in check_channel
    raise ValueError('channel must be in range 0..15')
ValueError: channel must be in range 0..15

and when you pass some nonsense as a keyword argument to the constructor or the copy() method:

>>> n.copy(note=['This', 'is', 'wrong'])
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "./mido/messages.py", line 316, in copy
    return Message(self.type, **args)
  File "./mido/messages.py", line 290, in __init__
    setattr(self, name, value)
  File "./mido/messages.py", line 327, in __setattr__
    ret = check(value)
  File "./mido/messages.py", line 181, in check_databyte
    raise TypeError('data byte must be an integer')
TypeError: data byte must be an integer

This means that the message object is always a valid MIDI message.

Ports

To create an output port and send a message:

>>> outport = mido.open_output()
>>> outport.send(msg)

To create an input port and receive a message:

>>> inport = mido.open_input()
>>> msg = inport.receive()

Note

Multiple threads can safely send and receive notes on the same port.

This will give you the default output and input ports. If you want to open a specific port, you will need its name. To get a list of all available input ports:

>>> mido.get_input_names()
['Midi Through Port-0', 'SH-201', 'Integra-7']
>>> inport = mido.open_input('SH-201')

All Mido ports can be used with the with statement, which will close the port for you:

with mido.open_input('SH-201') as inport:
    ...

To iterate through all incoming messages:

for msg in inport:
    ...

You can also receive and iterate over messages in a non-blocking way.

For more about ports, see Ports.

All Ports are Ports

The input and output ports used above are device ports, which communicate with a (physical or virtual) MIDI device.

Other port types include:

• MultiPort, which wraps around a set of ports and allow you to send to all of them or receive from all of them as if they were one.
• SocketPort, which communicates with another port over a TCP/IP (network) connection.
• IOPort, which wraps around an input and an output port and allows you to send and receive messages as if the two were the same port.

Ports of all types look and behave the same way, so they can be used interchangeably.

It’s easy to write new port types. See Writing a New Port.

Virtual Ports

Virtual ports allow you to create new ports that other applications can connect to:

with mido.open_input('New Port', virtual=True) as inport:
    for message in inport:
        print(message)

The port should now appear to other applications as “New Port”.

Unfortunately virtual ports are not supported by PortMidi and Pygame so this only works with RtMidi.

Parsing MIDI Bytes

Mido comes with a parser that allows you to turn bytes into messages. You can create a new parser:

>>> p = mido.Parser()
>>> p.feed([0x90, 0x40])
>>> p.feed_byte(0x60)

You can then fetch messages out of the parser:

>>> p.pending()
1
>>> for message in p:
...    print(message)
...
note_on channel=0 note=64 velocity=96 time=0

For more on parsers and parsing see Parsing MIDI Bytes.

Backends

Mido comes with backends for PortMidi and RtMidi and pygame. The default is PortMidi. You can select another backend or even use multiple backends at the same time. For more on this, see Backends.

Messages

A Mido message is a Python object with methods and attributes. The attributes will vary depending on message type.

To create a new message:

>>> mido.Message('note_on')
<message note_on channel=0 note=0 velocity=64 time=0>

You can pass attributes as keyword arguments:

>>> mido.Message('note_on', note=100, velocity=3, time=6.2)
<message note_on channel=0 note=100 velocity=3 time=6.2>

All attributes will default to 0. The exceptions are velocity, which defaults to 64 (middle velocity) and data which defaults to ().

You can set and get attributes as you would expect:

>>> msg = mido.Message('note_on')
>>> msg.note
0

The type attribute can be used to determine message type:

>>> msg.type
'note_on'

Attributes are also settable but it’s always better to use msg.copy():

>>> msg.copy(note=99, time=100.0)
<message note_on channel=0 note=99 velocity=64 time=100.0>

Mido supports all message types defined by the MIDI standard. For a full list of messages and their attributes, see Message Types.

Converting To Bytes

You can convert a message to MIDI bytes with one of these methods:

>>> msg = mido.Message('note_on')
>>> msg
<message note_on channel=0 note=0 velocity=64 time=0>
>>> msg.bytes()
[144, 0, 64]
>>> msg.bin()
bytearray(b'\x90\x00@')
>>> msg.hex()
'90 00 40'

You can turn bytes back into messages with the parser.

The Time Attribute

Each message has a time attribute, which can be set to any value of type int or float (and in Python 2 also long). What you do with this value is entirely up to you.

Some parts of Mido use the attribute for special purposes. In MIDI file tracks, it is used as delta time (in ticks).

Note

Before 1.1.18 the time attribute was not included in comparisons. If you want the old behavior the easies way is msg1.bytes() == msg2.bytes().

To sort messages on time you can do:

messages.sort(key=lambda message: message.time)

or:

import operator

messages.sort(key=operator.attrgetter('time'))

System Exclusive Messages

System Exclusive (SysEx) messages are used to send device specific data. The data attribute is a tuple of data bytes which serves as the payload of the message:

>>> msg = Message('sysex', data=[1, 2, 3])
>>> msg
<message sysex data=(1, 2, 3) time=0>
>>> msg.hex()
'F0 01 02 03 F7'

You can also extend the existing data:

>>> msg = Message('sysex', data=[1, 2, 3])
>>> msg.data += [4, 5]
>>> msg.data += [6, 7, 8]
>>> msg
<message sysex data=(1, 2, 3, 4, 5, 6, 7, 8) time=0>

Any sequence of integers is allowed, and type and range checking is applied to each data byte. These are all valid:

(65, 66, 67)
[65, 66, 67]
(i + 65 for i in range(3))
(ord(c) for c in 'ABC')
bytearray(b'ABC')
b'ABC'  # Python 3 only.

For example:

>>> msg = Message('sysex', data=bytearray(b'ABC'))
>>> msg.data += bytearray(b'DEF')
>>> msg
<message sysex data=(65, 66, 67, 68, 69, 70) time=0>

Ports

A Mido port is an object that can send or receive messages (or both).

You can open a port by calling one of the open methods, for example:

>>> inport = mido.open_input('SH-201')
>>> outport = mido.open_output('Integra-7')

Now you can receive messages on the input port and send messages on the output port:

>>> msg = inport.receive()
>>> outport.send(msg)

The message is copied by send(), so you can safely modify your original message without causing breakage in other parts of the system.

In this case, the ports are device ports, and are connected to some sort of (physical or virtual) MIDI device, but a port can be anything. For example, you can use a MultiPort receive messages from multiple ports as if they were one:

from mido.ports import MultiPort

...
multi = MultiPort([inport1, inport2, inport3])
for msg in multi:
    print(msg)

This will receive messages from all ports and print them out. Another example is a socket port, which is a wrapper around a TCP/IP socket.

No matter how the port is implemented internally or what it does, it will look and behave like any other Mido port, so all kinds of ports can be used interchangeably.

Note

Sending and receiving messages is thread safe. Opening and closing ports and listing port names are not.

Common Things

How to open a port depends on the port type. Device ports (PortMidi, RtMidi and others defined in backends) are opened with the open functions, for example:

port = mido.open_output()

Input and I/O ports (which support both input and output) are opened with open_input() and open_ioport() respectively. If you call these without a port name like above, you will get the (system specific) default port. You can override this by setting the MIDO_DEFAULT_OUTPUT etc. environment variables.

To get a list of available ports, you can do:

>>> mido.get_output_names()
['SH-201', 'Integra-7']

and then:

>>> port = mido.open_output('Integra-7')

There are corresponding function for input and I/O ports.

To learn how to open other kinds of ports, see the documentation for the port type in question.

The port name is available in port.name.

To close a port, call:

port.close()

or use the with statement to have the port closed automatically:

with mido.open_input() as port:
    for message in port:
        do_something_with(message)

You can check if the port is closed with:

if port.closed:
    print("Yup, it's closed.")

If the port is already closed, calling close() will simply do nothing.

Output Ports

Output ports basically have only one method:

outport.send(message)

This will send the message immediately. (Well, the port can choose to do whatever it wants with the message, but at least it’s sent.)

There are also a couple of utility methods:

outport.reset()

This will send “all notes off” and “reset all controllers” on every channel. This is used to reset everything to the default state, for example after playing back a song or messing around with controllers.

If you pass autoreset=True to the constructor, reset() will be called when the port closes:

with mido.open_output('Integra-7') as outport:
    for msg in inport:
        outport.send(msg)
# reset() is called here

outport.close()  # or here

Sometimes notes hang because a note_off has not been sent. To (abruptly) stop all sounding notes, you can call:

outport.panic()

This will not reset controllers. Unlike reset(), the notes will not be turned off gracefully, but will stop immediately with no regard to decay time.

Input Ports

To iterate over incoming messages::

for msg in port:
    print(msg)

This will iterate over messages as they arrive on the port until the port closes. (So far only socket ports actually close by themselves. This happens if the other end disconnects.)

You can also do non-blocking iteration:

for msg in port.iter_pending():
    print(msg)

This will iterate over all messages that have already arrived. It is typically used in main loops where you want to do something else while you wait for messages:

while True:
    for msg in port.iter_pending():
        print(msg)

    do_other_stuff()

In an event based system like a GUI where you don’t write the main loop you can install a handler that’s called periodically. Here’s an example for GTK:

def callback(self):
    for msg in self.inport:
        print(msg)

gobject.timeout_add_seconds(timeout, callback)

To get a bit more control you can receive messagas one at a time:

msg = port.receive()

This will block until a message arrives. To get a message only if one is available, you can use poll():

msg = port.poll()

This will return None if no message is available.

Note

For historical reasons there’s also a pending() method. It is no longer useful after iter_pending() and poll() were added but is kept around for backward compatibility.

Callbacks

Instead of reading from the port you can install a callback function which will be called for every message that arrives.

Here’s a simple callback function:

def print_message(message):
    print(message)

To install the callback you can either pass it when you create the port or later by setting the callback attribute:

port = mido.open_input(callback=print_message)
port.callback = print_message
...
port.callback = another_function

Note

Since the callback runs in a different thread you may need to use locks or other synchronization mechanisms to keep your main program and the callback from stepping on each other’s toes.

Calling receive(), __iter__(), pending() or iter_pending() on a port with a callback will raise an exception:

ValueError: a callback is set for this port

To clear the callback:

port.callback = None

This will return the port to normal.

Port API

Common Methods and Attributes

close()

Close the port. If the port is already closed this will simply do nothing.

name

Name of the port or None.

closed

True if the port is closed.

Output Port Methods

send(message)

Send a message.

reset()

Sends “all notes off” and “reset all controllers on all channels.

panic()

Sends “all sounds off” on all channels. This will abruptly end all sounding notes.

Input Port Methods

receive(block=True)

Receive a message. This will block until it returns a message. If block=True is passed it will instead return None if there is no message.

poll()

Returns a message, or None if there are no pending messages.

pending()

Returns the number of messages waiting to be received.

Note

This is kept around for backward compatibility. It’s better to use iter_pending() to iterate over pending messages.

iter_pending()

Iterates through pending messages.

__iter__()

Iterates through messages as they arrive on the port until the port closes.

MIDI Files

MidiFile objects can be used to read, write and play back MIDI files.

Opening a File

You can open a file with:

from mido import MidiFile

mid = MidiFile('song.mid')

Note

Sysex dumps such as patch data are often stored in SYX files rather than MIDI files. If you get “MThd not found. Probably not a MIDI file” try mido.read_syx_file(). (See SYX Files for more.)

The tracks attribute is a list of tracks. Each track is a list of messages and meta messages, with the time attribute of each messages set to its delta time (in ticks). (See Tempo and Beat Resolution below for more on delta times.)

To print out all messages in the file, you can do:

for i, track in enumerate(mid.tracks):
    print('Track {}: {}'.format(i, track.name))
    for message in track:
        print(message)

The entire file is read into memory. Thus you can freely modify tracks and messages, and save the file back by calling the save() method. (More on this below.)

Iterating Over Messages

Iterating over a MidiFile object will generate all MIDI messages in the file in playback order. The time attribute of each message is the number of seconds since the last message or the start of the file.

Meta messages will also be included. If you want to filter them out, you can do:

if isinstance(message, MetaMessage):
    ...

This makes it easy to play back a MIDI file on a port:

for message in MidiFile('song.mid'):
    time.sleep(message.time)
    if not isinstance(message, MetaMessage):
        port.send(message)

This is so useful that there’s a method for it:

for message in MidiFile('song.mid').play():
    port.send(message)

This does the sleeping and filtering for you. If you pass meta_messages=True you will also get meta messages. These can not be sent on ports, which is why they are off by default.

Creating a New File

You can create a new file by calling MidiFile without the filename argument. The file can then be saved by calling the save() method:

from mido import Message, MidiFile, MidiTrack

mid = MidiFile()
track = MidiTrack()
mid.tracks.append(track)

track.append(Message('program_change', program=12, time=0))
track.append(Message('note_on', note=64, velocity=64, time=32))
track.append(Message('note_off', note=64, velocity=127, time=32))

mid.save('new_song.mid')

The MidiTrack class is a subclass of list, so you can use all the usual methods.

All messages must be tagged with delta time (in ticks). (A delta time is how long to wait before the next message.)

If there is no ‘end_of_track’ message at the end of a track, one will be written anyway.

A complete example can be found in examples/midifiles/.

The save method takes either a filename (str) or, using the file keyword parameter, a file object such as an in-memory binary file (an io.BytesIO). If you pass a file object, save does not close it. Similarly, the MidiFile constructor can take either a filename, or a file object by using the file keyword parameter. if you pass a file object to MidiFile as a context manager, the file is not closed when the context manager exits. Examples can be found in test_midifiles2.py.

File Types

There are three types of MIDI files:

• type 0 (single track): all messages are saved in one track
• type 1 (synchronous): all tracks start at the same time
• type 2 (asynchronous): each track is independent of the others

When creating a new file, you can select type by passing the type keyword argument, or by setting the type attribute:

mid = MidiFile(type=2)
mid.type = 1

Type 0 files must have exactly one track. A ValueError is raised if you attempt to save a file with no tracks or with more than one track.

Playback Length

You can get the total playback time in seconds by accessing the length property:

mid.length

This is only supported for type 0 and 1 files. Accessing length on a type 2 file will raise ValueError, since it is impossible to compute the playback time of an asynchronous file.

Meta Messages

Meta messages behave like normal messages and can be created in the usual way, for example:

>>> from mido import MetaMessage
>>> MetaMessage('key_signature', key='C#', mode='major')
<meta message key_signature key='C#' mode='major' time=0>

You can tell meta messages apart from normal messages with:

if isinstance(message, MetaMessage):
    ...

or if you know the message type you can use the type attribute:

if message.type == 'key_signature':
    ...
elif message.type == 'note_on':
    ...

Meta messages can not be sent on ports.

For a list of supported meta messages and their attributes, and also how to implement new meta messages, see Meta Message Types.

About the Time Attribute

The time attribute is used in several different ways:

• inside a track, it is delta time in ticks. This must be an integer.
• in messages yielded from play(), it is delta time in seconds (time elapsed since the last yielded message)
• (only important to implementers) inside certain methods it is used for absolute time in ticks or seconds

Tempo and Beat Resolution

Timing in MIDI files is all centered around beats. A beat is the same as a quarter note.

Tempo is given in microseconds per beat, and beats are divided into ticks.

The default tempo is 500000 microseconds per beat (quarter note), which is half a second per beat or 120 beats per minute. The meta message ‘set_tempo’ can be used to change tempo during a song.

You can use bpm2tempo() and tempo2bpm() to convert to and from beats per minute. Note that tempo2bpm() may return a floating point number.

Computations:

beats_per_seconds = 1000000 / tempo
beats_per_minute = (1000000 / tempo) * 60
tempo = (60 / beats_per_minute) * 1000000

Examples:

2 == 1000000 / 500000
120 == (1000000 / 500000) * 60
500000 == (60 / 120.0) * 1000000

Each message in a MIDI file has a delta time, which tells how many ticks has passed since the last message. The length of a tick is defined in ticks per beat. This value is stored as ticks_per_beat in the file header and remains fixed throughout the song. It is used when converting delta times to and from real time.

(Todo: what’s the default value?)

Computations:

seconds_per_beat = tempo / 1000000.0
seconds_per_tick = seconds_per_beat / float(ticks_per_beat)
time_in_seconds = time_in_ticks * seconds_per_tick
time_in_ticks = time_in_seconds / seconds_per_tick

Examples:

0.5 == 500000 / 1000000.0
0.005 == 0.5 / 100
1.0 == 200 * 0.005
200 == 1.0 / 0.005

(Todo: update with default value.)

MidiFile objects have a ticks_per_beat attribute, while message.time is used for delta time. Tempo is updated by set_tempo meta messages.

SYX Files

SYX files are used to store SysEx messages, usually for patch data.

Reading and Writing

To read a SYX file:

messages = mido.read_syx_file('patch.syx')

To write a SYX file:

mido.write_syx_file('patch.syx', messages)

Non-sysex messages will be ignored.

Plain Text Format

Mido also supports plain text SYX files. These are read in exactly the same way:

messages = mido.read_syx_file('patch.txt')

read_syx_file() determins which format the file is by looking at the first byte. It Raises ValueError if file is plain text and byte is not a 2-digit hex number.

To write plain text:

mido.write_syx_file('patch.txt', messages, plaintext=True)

This will write the messages as hex encoded bytes with one message per line:

F0 00 01 5D 02 00 F7
F0 00 01 5D 03 00 F7

Backends

Choosing Backend

Mido comes with backends for PortMidi, RtMidi and Pygame.

RtMidi is the recommended backends. It has all the features of the other ones and more and is usually easier to install.

For historical reasons PortMidi is still the default. You can override this with the MIDO_BACKEND environment variable, for example:

$ MIDO_BACKEND=mido.backends.rtmidi ./program.py

Alternatively, you can set the backend from within your program:

>>> mido.set_backend('mido.backends.rtmidi')
>>> mido.backend
<backend mido.backends.rtmidi (not loaded)>

This will override the environment variable.

If you want to use more than one backend at a time, you can do:

rtmidi = mido.Backend('mido.backends.rtmidi')
portmidi = mido.Backend('mido.backends.portmidi')

input = rtmidi.open_input()
output = portmidi.open_output()
for message in input:
    output.send(message)

The backend will not be loaded until you call one of the open_ or get_ methods. You can pass load=True to have it loaded right away.

If you pass use_environ=True the module will use the environment variables MIDO_DEFAULT_INPUT etc. for default ports.

Environment Variables

You can override the backend’s choice of default ports with these three environment variables:

MIDO_DEFAULT_INPUT
MIDO_DEFAULT_OUTPUT
MIDO_DEFAULT_IOPORT

For example:

$ MIDO_DEFAULT_INPUT='SH-201' python program.py

or:

$ export MIDO_DEFAULT_OUTPUT='Integra-7'
$ python program1.py
$ python program2.py

RtMidi (Recommended)

Name: mido.backends.rtmidi

The RtMidi backend is a thin wrapper around python-rtmidi

Supports true blocking receive() in Python 3 which should be more efficient and result in lower latency.

Sends but doesn’t receive active sensing.

Callbacks use RtMidi’s own mechanism.

RtMidi is the only backend that can create virtual ports:

>>> port = mido.open_input('New Port', virtual=True)
>>> port
<open input 'New Port' (RtMidi/LINUX_ALSA)>

Other applications can now connect to this port. (One oddity is that, at least in Linux, RtMidi can’t see its own virtual ports, while PortMidi can see them.)

The RtMidi library can be compiled with support for more than one API. You can select API by adding it after the module name, either in the environment variable:

$ export MIDO_BACKEND=mido.backends.rtmidi/LINUX_ALSA
$ export MIDO_BACKEND=mido.backends.rtmidi/UNIX_JACK

or in one of these:

>>> mido.set_backend('mido.backends.rtmidi/LINUX_ALSA')
>>> mido.backend
<backend mido.backends.rtmidi/LINUX_ALSA (not loaded)>

>>> mido.Backend('mido.backends.rtmidi/UNIX_JACK')
<backend mido.backends.rtmidi/UNIX_JACK (not loaded)>

This allows you to, for example, use both ALSA and JACK ports in the same program.

To get a list of available APIs:

>>> mido.backend.module.get_api_names()
['LINUX_ALSA', 'UNIX_JACK']

There are a couple of problems with port names in Linux. First, RtMidi can’t see some software ports such as amSynth MIDI IN. PortMidi uses the same ALSA sequencer API, so this is problem in RtMidi.

Second, ports are named inconsistently. For example, the input port ‘Midi Through 14:0’ has a corresponding output named ‘Midi Through:0’. Unless this was intended, it is a bug in RtMidi’s ALSA implementation.

PortMidi

Name: mido.backends.portmidi

The PortMidi backend is written with ctypes and requires only the shared library file portmidi.so or portmidi.dll.

Can send but doesn’t receive active_sensing messages.

PortMidi has no callback mechanism, so callbacks are implemented in Python with threads. Each port with a callback has a dedicated thread doing blocking reads from the device.

Due to limitations in PortMidi the port list will not be up-to-date if there are any ports open. (The refresh is implemented by re-initalizing PortMidi which would break any open ports.)

Pygame

Name: mido.backends.pygame

Uses pygame.midi which is implemented on top of PortMidi.

Doesn’t receive active_sensing.

Callbacks are currently not implemented.

Parsing MIDI Bytes

MIDI is a binary protocol. Each each message is encoded as a status byte followed by up to three data bytes. (Sysex messages can have any number of data bytes and use a stop byte instead.)

Mido comes with a parser that turns MIDI bytes into messages. You can create a parser object, or call one of the utility functions:

>>> mido.parse([0x92, 0x10, 0x20])
<message note_on channel=0 note=16 velocity=32 time=0>

>>> mido.parse_all([0x92, 0x10, 0x20, 0x82, 0x10, 0x20])
[<message note_on channel=2 note=16 velocity=32 time=0>,
 <message note_off channel=2 note=16 velocity=32 time=0>]

These functions are just shortcuts for the full Parser class. This is the parser used inside input ports to parse incoming messages. Here are a few examples of how it can be used:

>>> p = mido.Parser()
>>> p.feed([0x90, 0x10, 0x20])
>>> p.pending()
1
>>> p.get_message()
<message note_on channel=0 note=16 velocity=32 time=0>

>>> p.feed_byte(0x90)
>>> p.feed_byte(0x10)
>>> p.feed_byte(0x20)
>>> p.feed([0x80, 0x10, 0x20])
<message note_on channel=0 note=16 velocity=32 time=0>

feed() accepts any iterable that generates integers in 0..255. The parser will skip and stray status bytes or data bytes, so you can safely feed it random data and see what comes out the other end.

get_message() will return None if there are no messages ready to be gotten.

You can also fetch parsed messages out of the parser by iterating over it:

>>> p.feed([0x92, 0x10, 0x20, 0x82, 0x10, 0x20])
>>> for message in p:
...    print(message)
note_on channel=2 note=16 velocity=32 time=0
note_off channel=2 note=16 velocity=32 time=0

The messages are available in p.messages (a collections.deque).

For the full table of MIDI binary encoding, see: http://www.midi.org/techspecs/midimessages.php

String Encoding

Mido messages can be serialized to a text format, which can be used to safely store messages in text files, send them across sockets or embed them in JSON, among other things.

To encode a message, simply call str() on it:

>>> cc = control_change(channel=9, control=1, value=122, time=60)
>>> str(cc)
'control_change channel=9 control=1 value=122 time=60'

Alternatively, you can the format_as_string function directly:

>>> mido.format_as_string(cc)
'control_change channel=9 control=1 value=122 time=60'

If you don’t need the time attribute or you want to store it elsewhere, you can pass include_time=False:

>>> mido.format_as_string(cc)
'control_change channel=9 control=1 value=122'

Format

The format is simple:

MESSAGE_TYPE [PARAMETER=VALUE ...]

These are the same as the arguments to mido.Message(). The order of parameters doesn’t matter, but each one can only appear once.

Only these character will ever occur in a string encoded Mido message:

[a-z][0-9][ =_.+()]

or written out:

'abcdefghijklmnopqrstuvwxyz0123456789 =_.+()'

This means the message can be embedded in most text formats without any form of escaping.

Parsing

To parse a message, you can use mido.parse_string():

>>> parse_string('control_change control=1 value=122 time=0.5')
<message control_change channel=0 control=1 value=122 time=0.5>

Parameters that are left out are set to their default values. ValueError is raised if the message could not be parsed. Extra whitespace is ignored:

>>> parse_string('  control_change   control=1  value=122')
<message control_change channel=0 control=1 value=122 time=0>

To parse messages from a stream, you can use mido.messages.parse_string_stream():

for (message, error) in parse_string_stream(open('some_music.text')):
    if error:
        print(error)
    else:
        do_something_with(message)

This will return every valid message in the stream. If a message could not be parsed, message will be None and error will be an error message describing what went wrong, as well as the line number where the error occurred.

The argument to parse_string_stream() can be any object that generates strings when iterated over, such as a file or a list.

parse_string_stream() will ignore blank lines and comments (which start with a # and go to the end of the line). An example of valid input:

# A very short song with an embedded sysex message.
note_on channel=9 note=60 velocity=120 time=0
# Send some data

sysex data=(1,2,3) time=0.5

pitchwheel pitch=4000  # bend the not a little time=0.7
note_off channel=9 note=60 velocity=60 time=1.0

Examples

And example of messages embedded in JSON:

{'messages': [
   '0.0 note_on channel=9 note=60 velocity=120',
   '0.5 sysex data=(1,2,3)',
   ...
])

Socket Ports - MIDI over TCP/IP

About Socket Ports

Socket ports allow you to send MIDI messages over a computer network.

The protocol is standard MIDI bytes over a TCP stream.

Caveats

The data is sent over an unencrypted channel. Also, the default server allows connections from any host and also accepts arbitrary sysex messages, which could allow anyone to for example overwrite patches on your synths (or worse). Use only on trusted networks.

If you need more security, you can build a custom server with a white list of clients that are allowed to connect.

If timing is critical, latency and jitter (especially on wireless networks) may make socket ports unusable.

Sending Messages to a Server

First, let’s import some things:

from mido.sockets import PortServer, connect

After that, a simple server is only two lines:

for message in PortServer('localhost', 8080):
    print(message)

You can then connect to the server and send it messages:

output = connect('localhost', 8080):
output.send(message)

Each end of the connection behaves like a normal Mido I/O port, with all the usual methods.

The host may be a DNS host name or IP address (as a string). It may also be ‘’, in which case connections are accepted on any ip address on the computer.

Turning Things on their Head

If you want the server to send messages the client, you can instead do:

server = PortServer('localhost', 8080):
while True:
    server.send(message)
    ...

and then on the client side:

for message in connect('localhost', 8080):
    print(message)

The client will now print any message that the server sends. Each message that the server sends will be received by all connected clients.

Under the Hood

The examples above use the server and client ports as normal I/O ports. This makes it easy to write simple servers, but you don’t have any control connections and the way messages are sent and received.

To get more control, you can ignore all the other methods of the PortServer object and use only accept(). Here’s a simple server implemented this way:

with PortServer('localhost', 8080) as server:
    while True:
        client = server.accept()
        for message in client:
            print(message)

accept() waits for a client to connect, and returns a SocketPort object which is connected to the SocketPort object returned by connect() at the other end.

The server above has one weakness: it allows only one connection at a time. You can get around this by using accept(block=False). This will return a SocketPort if there is a connection waiting and None if there is connection yet.

Using this, you can write the server any way you like, for example:

with PortServer('localhost', 8080) as server:
    clients = []
    while True:
        # Handle connections.
        client = server.accept(block=False)
        if client:
            print('Connection from {}'.format(client.name))
            clients.append(client)

        for i, client in reversed(enumerate(clients)):
            if client.closed:
                print('{} disconnected'.format(client.name))
                del clients[i]

        # Receive messages.
        for client in clients:
            for message in client.iter_pending()
                print('Received {} from {}'.format(message, client))

        # Do other things
        ...

Possible Future Additions

Optional HTTP-style headers could be added. As long as these are 7-bit ASCII, they will be counted as data bytes and ignored by clients or servers who don’t expect them.

Included Programs

These are installed with Mido.

mido-play

Plays back one or more MIDI files:

$ mido-play song1.mid song2.mid

mido-ports

Lists available input and output ports and shows environment variables and the current backend module.

mido-serve

Serves one or more ports over the network, for example:

$ mido-serve :9080 'Integra-7'

You can now connect to this port with mido-forward (or use mido.sockets.connect() and send messages to it. The messages will be forwarded to every port you listed (in this case ‘Integra-7’).

mido-connect

Forwards all messages that arrive on one or more ports to a server.

For example, to use the SH-201 keyboard connected to this computer to play sounds on the Integra-7 on a computer named mac.local (which runs the server as above), you can do:

$ mido-connect mac.local:9080 'SH-201'

Note that you may experience latency and jitter, so this may not be very useful for live playing or for playing back songs.

There is also no security built in, so you should only use this on a trusted network. (Anyone can connect and send anything, including harmful sysex messages.)

mido-serve and mido-connect are only included as fun programs to play with, but may in the future be expanded into something more usable.

Writing a New Port

The Mido port API allows you to write new ports to do practically anything.

A new port type can be defined by subclassing one of the base classes and overriding one or more methods. Here’s an example:

from mido.ports import BaseOutput

class PrintPort(BaseOutput):
    def _send(message):
        print(message)

>>> port = PrintPort()
>>> port.send(msg)
note_on channel=0 note=0 velocity=64 time=0

_send() will be called by send(), and is responsible for actually sending the message somewhere (or in this case print it out).

Overridable Methods

There are four overridable methods (all of them default to doing nothing):

``_open(self, **kwargs)``

Should do whatever is necessary to initialize the port (for example opening a MIDI device.)

Called by __init__(). The name attribute is already set when _open() is called, but you will get the rest of the keyword arguments.

If your port takes a different set of arguments or has other special needs, you can override __init__() instead.

_close(self)

Should clean up whatever resources the port has allocated (such as closing a MIDI device).

Called by close() if the port is not already closed.

_send(self, message)

(Output ports only.)

Should send the message (or do whatever else that makes sense).

Called by send() if the port is open and the message is a Mido message. (You don’t need any type checking here.)

Raise IOError if something goes wrong.

_receive(self, block=True)

(Input ports only.)

Should poll the device for available data and feed it to the parser.

Should not return anything. The caller will take care of this, and anything you return here will be ignored.

Is called by various input port methods, like receive() and pending(). The caller takes care of blocking and various error situations, so all you need to do is to feed data into the parser.

If block == True and the device supports blocking reads, you can loop and read until there is a message in _messages. See the seconds example below.

Raise IOError if something goes wrong.

Each method corresponds to the public method of the same name, and will be called by that method. The outer method will take care of many things, so the inner method only needs to do the very minimum. The outer method also provides the doc string, so you don’t have to worry about that.

The base classes are BaseInput, BaseOutput and BaseIOPort (which is a subclass of the other two.)

Examples

An full example of a device port for the imaginary MIDI library fjopp:

import fjopp
from mido.ports import BaseIOPort

# This defines an I/O port.
class FjoppPort(BaseIOPort):
    def _open(self, **kwargs):
        self._device = fjopp.open_device(self.name)

    def _close(self):
        self._device.close()

    def _send(self, message):
        self.device.write(message.bytes())

    def _receive(self, block=True):
        while True:
            data = self.device.read()
            if data:
                self._parser.feed(data)
            else:
                return

If fjopp supports blocking read, you can do this to actually block on the device instead of letting receive() and friends poll and wait for you:

def _receive(self, block=True):
    if block:
        # Actually block on the device.
        # (``read_blocking()`` will always return some data.)
        while not ``self._messages``:
            data = self._device.read_blocking()
            self._parser.feed(data)
    else:
        # Non-blocking read like above.
        while True:
            data = self.device.read()
            if data:
                 self._parser.feed(data)

This can be used for any kind of port that wants to block on a pipe, an socket or another input source. Note that Mido will still use polling and waiting when receiving from multiple ports (for example in a MultiPort).

If you want separate input and output classes, but the _open() and _close() methods have a lot in common, you can implement this using a mix-in.

Sometimes it’s useful to know inside the methods whether the port supports input or output. The way to do this is to check for the methods `send() and receive(), for example:

def _open(self, **kwargs):
    if hasattr(self, 'send'):
        # This is an output port.

    if hasattr(self, 'receive'):
        # This is an input port.

    if hasattr(self, 'send') and hasattr(self, 'receive'):
        # This is an I/O port.

Attributes

A port has some attributes that can be useful inside your methods.

name

The name of the port. The value is device specific and does not have to be unique. It can have any value, but must be a string or None.

This is set by __init__().

closed

True if the port is closed. You don’t have to worry about this inside your methods.

_messages

This is a collections.deque of messages that have been read and are ready to be received. This is a shortcut to _parser.messages.

_device_type (Optional.)

If this attribute exists, it’s a string which will be used in __repr__(). If it doesn’t exist, the class name will be used instead.

Writing a New Backend

A backend is a Python module with one or more of these:

Input -- an input port class
Output -- an output port class
IOPort -- an I/O port class
get_devices() -- returns a list of devices

Once written, the backend can be used by setting the environment variable MIDO_BACKEND or by calling mido.set_backend(). In both cases, the path of the module is used.

Input

And input class for open_input(). This is only required if the backend supports input.

Output

And output class for open_output(). This is only required if the backend supports output.

IOPort

An I/O port class for open_ioport(). If this is not found, open_ioport() will return mido.ports.IOPort(Input(), Output()).

get_devices(**kwargs)

Returns a list of devices, where each device is dictionary with at least these three values:

{
  'name': 'Some MIDI Input Port',
  'is_input': True,
  'is_output': False,
}

These are used to build return values for get_input_names() etc.. This function will also be available to the user directly.

For examples, see mido/backends/.

Freezing Mido Programs

PyInstaller

When you build an executable with PyInstaller and run it you may get import errors like this one:

ImportError: No module named mido.backends.portmidi

The reason is that Mido uses import_module() to import the backend modules, while PyInstaller looks for import statements.

The easiest fix is to import the module at the top of the program:

import mido
import mido.backends.portmidi  # The backend you want to use.
print(mido.get_input_names())

and then run pyinstaller like usual:

$ pyinstaller --onefile midotest.py
$ ./dist/midotest
[u'Midi Through Port-0']

If you don’t want to change the program, you can instead declare the backend module as a hidden import.

bbFreeze, py2exe, cx_Freeze, py2app, etc.

I suspect the same is true for these, but I have not had a chance to try it out yet.

Adding the explicit import statement should always work, though, since Mido backends are just normal Python modules.

About MIDI

A Short Introduction To MIDI

MIDI is a simple binary protocol for communicating with synthesizers and other electronic music equipment.

It was developed in 1981 by Dave Smith and Chet Wood of Sequential Systems. MIDI was quickly embraced by all the major synth manufacturers and led to developments such as microcomputer sequencers, and with them the electronic home studio. Although many attempts have been made to replace it, it is still the industry standard.

MIDI was designed for the 8-bit micro controllers found in synthesizers at the beginning of the 80’s. As such, it is a very minimal byte-oriented protocol. The message for turning a note on is only three bytes long (here shown in hexadecimal):

92 3C 64

This message consists of:

92 -- 9 == message type note on
      2 == channel 2

3C -- note 60 (middle C)

64 -- velocity (how hard the note is hit)

The first byte is called a status byte. It has the upper bit set, which is how you can tell it apart from the following data bytes. Data bytes are thus only 7 bits (0..127).

Each message type has a given number of data bytes, the exception being the System Exclusive message which has a start and a stop byte and any number of data bytes in-between these two:

F0 ... F7

Messages can be divided into four groups:

• Channel messages. These are used to turn notes on and off, to change patches, and change controllers (pitch bend, modulation wheel, pedal and many others). There are 16 channels, and the channel number is encoded in the lower 4 bits of the status byte. Each synth can choose which channel (or channels) it responds to. This can typically be configured.
• System common messages.
• System real time messages, the include start, stop, continue, song position (for playback of songs) and reset.
• System Exclusive messages (often called Sysex messages). These are used for sending and receiving device specific such as patch data.

Some Examples of Messages

# Turn on middle C on channel 2:
92 3C 64

# Turn it back off:
82 3C 64

# Change to program (sound) number 4 on channel 2:
C2 04

# Continue (Starts a song that has been paused):
FB

# Sysex data request for the Roland SH-201 synthesizer:
F0 41 10 00 00 16 11 20 00 00 00 00 00 00 21 3F F7

Further Reading

• An Introduction to MIDI
• MIDI Basics (by Yamaha)
• Wikipedia’s page on MIDI
• MIDI Manufacturers Association
• A full table of MIDI messages

Message Types

Supported Messages

Name	Keyword Arguments / Attributes
note_off	channel note velocity
note_on	channel note velocity
polytouch	channel note value
control_change	channel control value
program_change	channel program
aftertouch	channel value
pitchwheel	channel pitch
sysex	data
quarter_frame	frame_type frame_value
songpos	pos
song_select	song
tune_request
clock
start
continue
stop
active_sensing
reset

quarter_frame is used for SMPTE time codes. See: http://www.electronics.dit.ie/staff/tscarff/Music_technology/midi/MTC.htm

Parameter Types

Name	Valid Range	Default Value
channel	0..15	0
frame_type	0..7	0
frame_value	0..15	0
control	0..127	0
note	0..127	0
program	0..127	0
song	0..127	0
value	0..127	0
velocity	0..127	64
data	(0..127, 0..127, …)	() (empty tuple)
pitch	-8192..8191	0
pos	0..16383	0
time	any integer or float	0

Note

Mido numbers channels 0 to 15 instead of 1 to 16. This makes them easier to work with in Python but you may want to add and subtract 1 when communicating with the user.

velocity is how fast the note was struck or released. It defaults to 64 so that if you don’t set it, you will still get a reasonable value. (64 is the recommended default for devices that don’t support it attack or release velocity.)

The time parameter is not included in the encoded message, and is (currently) not used by Mido in any way. You can use it for whatever purpose you wish.

The data parameter accepts any iterable that generates numbers in 0..127. This includes:

mido.Message('sysex', data=[1, 2, 3])
mido.Message('sysex', data=range(10))
mido.Message('sysex', data=(i for i in range(10) if i % 2 == 0))

For details about the binary encoding of a MIDI message, see:

http://www.midi.org/techspecs/midimessages.php

Meta Message Types

Supported Messages

sequence_number (0x00)

Attribute	Values	Default
number	0..65535	0

Sequence number in type 0 and 1 MIDI files; pattern number in type 2 MIDI files.

text (0x01)

Attribute	Values	Default
text	string	‘’

General “Text” Meta Message. Can be used for any text based data.

copyright (0x02)

Attribute	Values	Default
text	string	‘’

Provides information about a MIDI file’s copyright.

track_name (0x03)

Attribute	Values	Default
name	string	‘’

Stores a MIDI track’s name.

instrument_name (0x04)

Attribute	Values	Default
name	string	‘’

Stores an instrument’s name.

lyrics (0x05)

Attribute	Values	Default
text	string	‘’

Stores the lyrics of a song. Typically one syllable per Meta Message.

marker (0x06)

Attribute	Values	Default
text	string	‘’

Marks a point of interest in a MIDI file. Can be used as the marker for the beginning of a verse, solo, etc.

cue_marker (0x07)

Attribute	Values	Default
text	string	‘’

Marks a cue. IE: ‘Cue performer 1’, etc

device_name (0x09)

Attribute	Values	Default
name	string	‘’

Gives the name of the device.

channel_prefix (0x20)

Attribute	Values	Default
channel	0..255	0

Gives the prefix for the channel on which events are played.

midi_port (0x21)

Attribute	Values	Default
port	0..255	0

Gives the MIDI Port on which events are played.

end_of_track (0x2f)

Attribute	Values	Default
n/a	n/a	n/a

An empty Meta Message that marks the end of a track.

set_tempo (0x51)

Attribute	Values	Default
tempo	0..16777215	500000

Tempo is in microseconds per beat (quarter note). You can use bpm2tempo() and tempo2bpm() to convert to and from beats per minute. Note that tempo2bpm() may return a floating point number.

smpte_offset (0x54)

Attribute	Values	Default
frame_rate	24, 25, 29.97, 30	24
hours	0..255	0
minutes	0..59	0
seconds	0..59	0
frames	0..255	0
sub_frames	0..99	0

time_signature (0x58)

Attribute	Values	Default
numerator	0..255	4
denominator	1..2**255	4
clocks_per_click	0..255	24
notated_32nd_notes_per_beat	0..255	8

Time signature of:

4/4 : MetaMessage(‘time_signature’, numerator=4, denominator=4)

3/8 : MetaMessage(‘time_signature’, numerator=3, denominator=8)

key_signature (0x59)

Attribute	Values	Default
key	‘C’, ‘F#m’, …	‘C’

Valid values: A A#m Ab Abm Am B Bb Bbm Bm C C# C#m Cb Cm D D#m Db Dm E Eb Ebm Em F F# F#m Fm G G#m Gb Gm

Note: the mode attribute was removed in 1.1.5. Instead, an ‘m’ is appended to minor keys.

sequencer_specific (0x7f)

Attribute	Values	Default
data	[..]	[]

An unprocessed sequencer specific message containing raw data.

Unknown Meta Messages

Unknown meta messages will be returned as UnknownMetaMessage objects, with type set to unknown_meta. The messages are saved back to the file exactly as they came out.

Code that depends on UnknownMetaMessage may break if the message in question is ever implemented, so it’s best to only use these to learn about the format of the new message and then implement it as described below.

UnknownMetaMessage have two attributes:

``type_byte`` - a byte which uniquely identifies this message type
``_data`` - the message data as a list of bytes

These are also visible in the repr() string:

<unknown meta message _type_byte=0x## _data=[...], time=0>

Implementing New Meta Messages

If you come across a meta message which is not implemented, or you want to use a custom meta message, you can add it by writing a new meta message spec:

from mido.midifiles import MetaSpec, add_meta_spec

class MetaSpec_light_color(MetaSpec):
    type_byte = 0xf0
    attributes = ['r', 'g', 'b']
    defaults = [0, 0, 0]

def decode(self, message, data):
    # Interpret the data bytes and assign them to attributes.
    (message.r, message.g, message.b) = data

def encode(self, message):
    # Encode attributes to data bytes and
    # return them as a list of ints.
    return [message.r, message.g, message.b]

def check(self, name, value):
    # (Optional)
    # This is called when the user assigns
    # to an attribute. You can use this for
    # type and value checking. (Name checking
    # is already done.
    #
    # If this method is left out, no type and
    # value checking will be done.

    if not isinstance(value, int):
        raise TypeError('{} must be an integer'.format(name))

    if not 0 <= value <= 255:
        raise TypeError('{} must be in range 0..255'.format(name))

Then you can add your new message type with:

add_meta_spec(MetaSpec_light_color)

and create messages in the usual way:

>>> from mido import MetaMessage
>>> MetaMessage('light_color', r=120, g=60, b=10)
<meta message light_color r=120 g=60 b=10 time=0>

and the new message type will now work when reading and writing MIDI files.

Some additional functions are available:

encode_string(unicode_string)
decode_string(byte_list)

These convert between a Unicode string and a list of bytes using the current character set in the file.

If your message contains only one string with the attribute name text or name, you can subclass from one of the existing messages with these attributes, for example:

class MetaSpec_copyright(MetaSpec_text):
    type_byte = 0x02

class MetaSpec_instrument_name(MetaSpec_track_name):
    type_byte = 0x04

This allows you to skip everything but type_byte, since the rest is inherited.

See the existing MetaSpec classes for further examples.

Library Reference

Messages

class mido.Message(type, **arguments)

MIDI message class.

bin()

Encode message and return as a bytearray.

This can be used to write the message to a file.

bytes()

Encode message and return as a list of integers.

copy(**overrides)

Return a copy of the message.

Attributes will be overridden by the passed keyword arguments. Only message specific attributes can be overridden. The message type can not be changed.

Example:

a = Message(‘note_on’) b = a.copy(velocity=32)

hex(sep=' ')

Encode message and return as a string of hex numbers,

Each number is separated by the string sep.

Ports

mido.open_input(name=None, virtual=False, callback=None, **kwargs)

Open an input port.

If the environment variable MIDO_DEFAULT_INPUT is set, if will override the default port.

virtual=False

Passing True opens a new port that other applications can connect to. Raises IOError if not supported by the backend.

callback=None

A callback function to be called when a new message arrives. The function should take one argument (the message). Raises IOError if not supported by the backend.

mido.open_output(name=None, virtual=False, autoreset=False, **kwargs)

Open an output port.

If the environment variable MIDO_DEFAULT_OUTPUT is set, if will override the default port.

virtual=False

Passing True opens a new port that other applications can connect to. Raises IOError if not supported by the backend.

autoreset=False

Automatically send all_notes_off and reset_all_controllers on all channels. This is the same as calling port.reset().

mido.open_ioport(name=None, virtual=False, callback=None, autoreset=False, **kwargs)

Open a port for input and output.

If the environment variable MIDO_DEFAULT_IOPORT is set, if will override the default port.

virtual=False

Passing True opens a new port that other applications can connect to. Raises IOError if not supported by the backend.

callback=None

A callback function to be called when a new message arrives. The function should take one argument (the message). Raises IOError if not supported by the backend.

autoreset=False

Automatically send all_notes_off and reset_all_controllers on all channels. This is the same as calling port.reset().

mido.get_input_names(**kwargs)

Return a sorted list of all input port names.

mido.get_output_names(**kwargs)

Return a sorted list of all output port names.

mido.get_ioport_names(**kwargs)

Return a sorted list of all I/O port names.

Backends

mido.set_backend(name=None)

Set current backend.

name can be a module name like ‘mido.backends.rtmidi’ or a Backend object.

If no name is passed, the default backend will be used.

This will replace all the open_*() and get_*_name() functions in top level mido module. The module will be loaded the first time one of those functions is called.

class mido.Backend(name=None, api=None, load=False, use_environ=True)

Wrapper for backend module.

A backend module implements classes for input and output ports for a specific MIDI library. The Backend object wraps around the object and provides convenient ‘open_*()’ and ‘get_*_names()’ functions.

get_input_names(**kwargs)

Return a sorted list of all input port names.

get_ioport_names(**kwargs)

Return a sorted list of all I/O port names.

get_output_names(**kwargs)

Return a sorted list of all output port names.

load()

Load the module.

Does nothing if the module is already loaded.

This function will be called if you access the ‘module’ property.

loaded

Return True if the module is loaded.

module

A reference module implementing the backend.

This will always be a valid reference to a module. Accessing this property will load the module. Use .loaded to check if the module is loaded.

open_input(name=None, virtual=False, callback=None, **kwargs)

Open an input port.

If the environment variable MIDO_DEFAULT_INPUT is set, if will override the default port.

virtual=False

Passing True opens a new port that other applications can connect to. Raises IOError if not supported by the backend.

callback=None

A callback function to be called when a new message arrives. The function should take one argument (the message). Raises IOError if not supported by the backend.

open_ioport(name=None, virtual=False, callback=None, autoreset=False, **kwargs)

Open a port for input and output.

If the environment variable MIDO_DEFAULT_IOPORT is set, if will override the default port.

virtual=False

Passing True opens a new port that other applications can connect to. Raises IOError if not supported by the backend.

callback=None

A callback function to be called when a new message arrives. The function should take one argument (the message). Raises IOError if not supported by the backend.

autoreset=False

Automatically send all_notes_off and reset_all_controllers on all channels. This is the same as calling port.reset().

open_output(name=None, virtual=False, autoreset=False, **kwargs)

Open an output port.

If the environment variable MIDO_DEFAULT_OUTPUT is set, if will override the default port.

virtual=False

Passing True opens a new port that other applications can connect to. Raises IOError if not supported by the backend.

autoreset=False

Automatically send all_notes_off and reset_all_controllers on all channels. This is the same as calling port.reset().

Parsing

mido.parse(data)

Parse MIDI data and return the first message found.

Data after the first message is ignored. Use parse_all() to parse more than one message.

mido.parse_all(data)

Parse MIDI data and return a list of all messages found.

This is typically used to parse a little bit of data with a few messages in it. It’s best to use a Parser object for larger amounts of data. Also, tt’s often easier to use parse() if you know there is only one message in the data.

class mido.Parser(data=None)

MIDI Parser

Parses a stream of bytes and produces messages.

Data can be put into the parser in the form of integers, byte arrays or byte strings.

feed(data)

Feed MIDI data to the parser.

Accepts any object that produces a sequence of integers in range 0..255, such as:

[0, 1, 2] (0, 1, 2) [for i in range(256)] (for i in range(256)] bytearray() b’’ # Will be converted to integers in Python 2.

feed_byte(byte)

Feed one MIDI byte into the parser.

The byte must be an integer in range 0..255.

get_message()

Get the first parsed message.

Returns None if there is no message yet. If you don’t want to deal with None, you can use pending() to see how many messages you can get before you get None.

pending()

Return the number of pending messages.

MIDI Files

class mido.MidiFile(filename=None, file=None, type=1, ticks_per_beat=480, charset='latin1', debug=False)

add_track(name=None)

Add a new track to the file.

This will create a new MidiTrack object and append it to the track list.

length

Playback time in seconds.

This will be computed by going through every message in every track and adding up delta times.

play(meta_messages=False)

Play back all tracks.

The generator will sleep between each message by default. Messages are yielded with correct timing. The time attribute is set to the number of seconds slept since the previous message.

By default you will only get normal MIDI messages. Pass meta_messages=True if you also want meta messages.

You will receive copies of the original messages, so you can safely modify them without ruining the tracks.

print_tracks(meta_only=False)

Prints out all messages in a .midi file.

May take argument meta_only to show only meta messages.

Use: print_tracks() -> will print all messages print_tracks(meta_only=True) -> will print only MetaMessages

save(filename=None, file=None)

Save to a file.

If file is passed the data will be saved to that file. This is typically an in-memory file or and already open file like sys.stdout.

If filename is passed the data will be saved to that file.

Raises ValueError if both file and filename are None, or if a type 0 file has != one track.

class mido.MidiTrack

append()

Append object to the end of the list.

clear()

Remove all items from list.

copy()

Return a shallow copy of the list.

count()

Return number of occurrences of value.

extend()

Extend list by appending elements from the iterable.

index()

Return first index of value.

Raises ValueError if the value is not present.

insert()

Insert object before index.

name

Name of the track.

This will return the name from the first track_name meta message in the track, or ‘’ if there is no such message.

Setting this property will update the name field of the first track_name message in the track. If no such message is found, one will be added to the beginning of the track with a delta time of 0.

pop()

Remove and return item at index (default last).

Raises IndexError if list is empty or index is out of range.

remove()

Remove first occurrence of value.

Raises ValueError if the value is not present.

reverse()

Reverse IN PLACE.

sort()

Stable sort IN PLACE.

class mido.MetaMessage(type_, **kwargs)

bin()

Encode message and return as a bytearray.

This can be used to write the message to a file.

bytes()

copy(**overrides)

Return a copy of the message.

Attributes will be overridden by the passed keyword arguments. Only message specific attributes can be overridden. The message type can not be changed.

Example:

a = Message(‘note_on’) b = a.copy(velocity=32)

hex(sep=' ')

Encode message and return as a string of hex numbers,

Each number is separated by the string sep.

mido.bpm2tempo(bpm)

Convert beats per minute to MIDI file tempo.

Returns microseconds per beat as an integer:

240 => 250000
120 => 500000
60 => 1000000

mido.tempo2bpm(tempo)

Convert MIDI file tempo to BPM.

Returns BPM as an integer or float:

250000 => 240
500000 => 120
1000000 => 60

mido.merge_tracks(tracks)

Returns a MidiTrack object with all messages from all tracks.

The messages are returned in playback order with delta times as if they were all in one track.

SYX Files

mido.read_syx_file(filename)

Read sysex messages from SYX file.

Returns a list of sysex messages.

This handles both the text (hexadecimal) and binary formats. Messages other than sysex will be ignored. Raises ValueError if file is plain text and byte is not a 2-digit hex number.

mido.write_syx_file(filename, messages, plaintext=False)

Write sysex messages to a SYX file.

Messages other than sysex will be skipped.

By default this will write the binary format. Pass plaintext=True to write the plain text format (hex encoded ASCII text).

Port Classes and Functions

class mido.ports.BaseInput(name='', **kwargs)

Base class for input port.

Subclass and override _receive() to create a new input port type. (See portmidi.py for an example of how to do this.)

close()

Close the port.

If the port is already closed, nothing will happen. The port is automatically closed when the object goes out of scope or is garbage collected.

iter_pending()

Iterate through pending messages.

pending()

Return how many messages are ready to be received.

Note: This is kept around for backward compatibility. It’s better to use iter_pending() to iterate over pending messages.

This will read data from the device and put it in the parser. I will then return the number of messages available to be received.

The value will not be reliable when receiving messages in multiple threads.

If this is called on a closed port it will work as normal except it won’t try to read from the device.

poll()

Receive the next pending message or None

This is the same as calling receive(block=False).

receive(block=True)

Return the next message.

This will block until a message arrives.

If you pass block=False it will not block and instead return None if there is no available message.

If the port is closed and there are no pending messages IOError will be raised. If the port closes while waiting inside receive(), IOError will be raised. Todo: this seems a bit inconsistent. Should different errors be raised? What’s most useful here?

class mido.ports.BaseOutput(name='', autoreset=False, **kwargs)

Base class for output port.

Subclass and override _send() to create a new port type. (See portmidi.py for how to do this.)

close()

Close the port.

If the port is already closed, nothing will happen. The port is automatically closed when the object goes out of scope or is garbage collected.

panic()

Send “All Sounds Off” on all channels.

This will mute all sounding notes regardless of envelopes. Useful when notes are hanging and nothing else helps.

reset()

Send “All Notes Off” and “Reset All Controllers” on all channels

send(message)

Send a message on the port.

A copy of the message will be sent, so you can safely modify the original message without any unexpected consequences.

class mido.ports.IOPort(input, output)

Input / output port.

This is a convenient wrapper around an input port and an output port which provides the functionality of both. Every method call is forwarded to the appropriate port.

close()

Close the port.

If the port is already closed, nothing will happen. The port is automatically closed when the object goes out of scope or is garbage collected.

iter_pending()

Iterate through pending messages.

panic()

Send “All Sounds Off” on all channels.

This will mute all sounding notes regardless of envelopes. Useful when notes are hanging and nothing else helps.

pending()

Return how many messages are ready to be received.

Note: This is kept around for backward compatibility. It’s better to use iter_pending() to iterate over pending messages.

This will read data from the device and put it in the parser. I will then return the number of messages available to be received.

The value will not be reliable when receiving messages in multiple threads.

If this is called on a closed port it will work as normal except it won’t try to read from the device.

poll()

Receive the next pending message or None

This is the same as calling receive(block=False).

receive(block=True)

Return the next message.

This will block until a message arrives.

If you pass block=False it will not block and instead return None if there is no available message.

If the port is closed and there are no pending messages IOError will be raised. If the port closes while waiting inside receive(), IOError will be raised. Todo: this seems a bit inconsistent. Should different errors be raised? What’s most useful here?

reset()

Send “All Notes Off” and “Reset All Controllers” on all channels

send(message)

Send a message on the port.

A copy of the message will be sent, so you can safely modify the original message without any unexpected consequences.

class mido.ports.MultiPort(ports, yield_ports=False)

close()

Close the port.

If the port is already closed, nothing will happen. The port is automatically closed when the object goes out of scope or is garbage collected.

iter_pending()

Iterate through pending messages.

panic()

Send “All Sounds Off” on all channels.

This will mute all sounding notes regardless of envelopes. Useful when notes are hanging and nothing else helps.

pending()

Return how many messages are ready to be received.

Note: This is kept around for backward compatibility. It’s better to use iter_pending() to iterate over pending messages.

This will read data from the device and put it in the parser. I will then return the number of messages available to be received.

The value will not be reliable when receiving messages in multiple threads.

If this is called on a closed port it will work as normal except it won’t try to read from the device.

poll()

Receive the next pending message or None

This is the same as calling receive(block=False).

receive(block=True)

Return the next message.

This will block until a message arrives.

If you pass block=False it will not block and instead return None if there is no available message.

If the port is closed and there are no pending messages IOError will be raised. If the port closes while waiting inside receive(), IOError will be raised. Todo: this seems a bit inconsistent. Should different errors be raised? What’s most useful here?

reset()

Send “All Notes Off” and “Reset All Controllers” on all channels

send(message)

Send a message on the port.

A copy of the message will be sent, so you can safely modify the original message without any unexpected consequences.

mido.ports.multi_receive(ports, yield_ports=False, block=True)

Receive messages from multiple ports.

Generates messages from ever input port. The ports are polled in random order for fairness, and all messages from each port are yielded before moving on to the next port.

If yield_ports=True, (port, message) is yielded instead of just the message.

If block=False only pending messages will be yielded.

mido.ports.multi_iter_pending(ports, yield_ports=False)

Iterate through all pending messages in ports.

This is the same as calling multi_receive(ports, block=False). The function is kept around for backwards compatability.

mido.ports.sleep()

Sleep for N seconds.

This is used in ports when polling and waiting for messages. N can be set with set_sleep_time().

mido.ports.set_sleep_time(seconds=0.001)

Set the number of seconds sleep() will sleep.

mido.ports.get_sleep_time()

Get number of seconds sleep() will sleep.

Socket Ports

class mido.sockets.PortServer(host, portno, backlog=1)

accept(block=True)

Accept a connection from a client.

Will block until there is a new connection, and then return a SocketPort object.

If block=False, None will be returned if there is no new connection waiting.

close()

Close the port.

If the port is already closed, nothing will happen. The port is automatically closed when the object goes out of scope or is garbage collected.

iter_pending()

Iterate through pending messages.

panic()

Send “All Sounds Off” on all channels.

This will mute all sounding notes regardless of envelopes. Useful when notes are hanging and nothing else helps.

pending()

Return how many messages are ready to be received.

Note: This is kept around for backward compatibility. It’s better to use iter_pending() to iterate over pending messages.

This will read data from the device and put it in the parser. I will then return the number of messages available to be received.

The value will not be reliable when receiving messages in multiple threads.

If this is called on a closed port it will work as normal except it won’t try to read from the device.

poll()

Receive the next pending message or None

This is the same as calling receive(block=False).

receive(block=True)

Return the next message.

This will block until a message arrives.

If you pass block=False it will not block and instead return None if there is no available message.

If the port is closed and there are no pending messages IOError will be raised. If the port closes while waiting inside receive(), IOError will be raised. Todo: this seems a bit inconsistent. Should different errors be raised? What’s most useful here?

reset()

Send “All Notes Off” and “Reset All Controllers” on all channels

send(message)

Send a message on the port.

A copy of the message will be sent, so you can safely modify the original message without any unexpected consequences.

class mido.sockets.SocketPort(host, portno, conn=None)

close()

Close the port.

If the port is already closed, nothing will happen. The port is automatically closed when the object goes out of scope or is garbage collected.

iter_pending()

Iterate through pending messages.

panic()

Send “All Sounds Off” on all channels.

This will mute all sounding notes regardless of envelopes. Useful when notes are hanging and nothing else helps.

pending()

Return how many messages are ready to be received.

Note: This is kept around for backward compatibility. It’s better to use iter_pending() to iterate over pending messages.

This will read data from the device and put it in the parser. I will then return the number of messages available to be received.

The value will not be reliable when receiving messages in multiple threads.

If this is called on a closed port it will work as normal except it won’t try to read from the device.

poll()

Receive the next pending message or None

This is the same as calling receive(block=False).

receive(block=True)

Return the next message.

This will block until a message arrives.

If you pass block=False it will not block and instead return None if there is no available message.

If the port is closed and there are no pending messages IOError will be raised. If the port closes while waiting inside receive(), IOError will be raised. Todo: this seems a bit inconsistent. Should different errors be raised? What’s most useful here?

reset()

Send “All Notes Off” and “Reset All Controllers” on all channels

send(message)

Send a message on the port.

A copy of the message will be sent, so you can safely modify the original message without any unexpected consequences.

mido.sockets.parse_address(address)

Parse and address on the format host:port.

Returns a tuple (host, port). Raises ValueError if format is invalid or port is not an integer or out of range.

Resources

• MIDI Manufacturers Association (midi.org)
• Table of MIDI Messages (midi.org)
• Tech Specs & Info (midi.org)
• MIDI (Wikipedia)
• Essentials of the MIDI Protocol (Craig Stuart Sapp, CCRMA)
• Outline of the Standard MIDI File Structure (Craig Stuart Sapp, CCRMA)
• Active Sense (About the active sensing message.)
• Active Sensing (Sweetwater)
• MIDI Technical/Programming Docs (Jeff Glatt)
• Standard MIDI Files (cnx.org)
• MIDI File Parsing (Course assignment in Music 253 at Stanford University)
• MIDI File Format (The Sonic Spot)
• Delta time and running status (mic at recordingblogs.com)
• MIDI meta messages (recordingblog.com)
• Meta Message (Sound On Sound)

License

The MIT License (MIT)

Copyright (c) 2013-infinity Ole Martin Bjørndalen

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the “Software”), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

Authors

Ole Martin Bjørndalen (lead programmer)

Rapolas Binkys

Acknowledgements

Thanks to /u/tialpoy/ on Reddit for extensive code review and helpful suggestions.

Thanks to everyone who has sent bug reports and patches.

The PortMidi wrapper is based on portmidizero by Grant Yoshida.

Indices and tables

• Index
• Module Index
• Search Page