Since discovering that the classic baseball tune Take Me Out To The Ballgame was in the public domain, I decided that I might like to have a version of it that I knew was free to use however I might like to. I found out about the ABC Music Project. These programs were principally used by people researching folk music, but allow you to produce sheet music and playable MIDI files from the same source code. They aren’t entirely intuitive, but they do work. A couple of hours of work and I have the tune as an mp3 file and typeset as a PDF file.

The really cool thing about this is that it allows you to create one common source format for music that can be converted into two useful forms: both MIDI files for performance and sheet music for instruction. Try looking around, there is already quite a bit of music in ABC format.