The abcMIDI package contains four programs: abc2midi to convert ABC
music notation to MIDI, midi2abc to convert MIDI files to (a first
approximation to) the corresponding ABC, abc2abc to reformat and/or
transpose ABC files, and yaps to typeset ABC files as PostScript.
For a description of the ABC syntax, please see the ABC userguide
which is a part of the abcm2ps.
A mirror github repo is at https://github.com/sdgathman/abcmidi