PyPortMidi is a Python wrapper for PortMidi. PortMidi is a cross-platform C library for realtime MIDI control. Using pyPortMidi, you can send and receive MIDI data in realtime from Python.

Besides using pyPortMidi to communicate to synthesizers and the like, it is possible to use pyPortMidi as a way to send MIDI messages between software packages on the same computer.

The original code is from John Harrison. See http://python-pyrex.media.mit.edu/~harrison/pyportmidi.html