The abcMIDI package contains four programs: abc2midi to convert ABC music
notation to midi, midi2abc to convert midi files to (a first approximation
of) 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 user guide
which is a part of the abc2mtex package written by Chris Walshaw.