A small example (API may change):

import time
import random
from protomidi.msg import *
from protomidi.portmidi import Output

# Play random notes
out = Output()
while 1:
    note = random.randrange(128)

    out.send(note_on(note=note, velocity=70))
time.sleep(0.25)
out.send(note_off(note=note, velocity=127))

MIDI messages are immutable objects. A new message can be created by calling an existing message and overriding some of its values:

>>> from protomidi.msg import note_on
>>> msg = note_on(note=22, velocity=100)
>>> msg
note_on(channel=0, note=22, velocity=100)
>>> msg(note=60)
note_on(channel=0, note=60, velocity=100)

(All implemented, but with a lot of testing and fine polishing remaining.)

• abstract immutable MIDI message objects that are easy to work with
• support for all MIDI message types (including sysex)
• parser / serializer (seralizes to bytearray or bytes)
• Input and Output classes for communicating with other MIDI programs or devices (portmidi)

The library is under development. The code may not be stable and the API may change.

• on OS X, portmidi sometimes hangs for a couple of seconds while initializing.
• default input/output doesn't work in Linux. Adding a default input/output in the alsa config will probably help. (This is not really a bug, but just how ALSA works.)
• in Linux, I am experiencing occational short lags, as if messages are bunched up and then released again. I don't know what causes this, but I suspect that another process is sometimes stealing the CPU for long enough for this to happen. (Could it be garbage collection? I doubt it, but I won't count it out yet.)

ProtoMIDI works Python 2.7 and 3.2 (may work with older versions, but I haven't tested this.)

Requires portmidi shared library if you want to use the I/O classes.

I'm using Ubuntu 11.4 and Mac OS Lion, but it should run wherever there you have Python and a portmidi shared library.

• show sysex bytes in hexadecimal? (in __repr__())
• include some kind of event based scheduler (perhaps based on http://github/olemb/gametime)
• include useful lookup tables or message attributes for common things like controller types
• handle devices that send note_on(velocity=0) instead of note_off() (flag for portmidi.Input()?) Perhaps make it an option so you can choose the one you prefer, and any data will be converted to that format.

Author: Ole Martin Bjørndalen - ombdalen@gmail.com - http://nerdly.info/ole/

License: MIT

Credits: The Portmidi wrapper is based on Portmidizero by Grant Yoshida.