https://code.google.com/archive/p/midiutil/

MIDIUtil is a pure Python library that allows one to write muti-track Musical Instrument Digital Interface (MIDI) files from within Python programs. It is object-oriented and allows one to create and write these files with a minimum of fuss.

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