Due to quite a few requests, MIDI support is starting to be implemented. Right now support for ABC notation, which makes use of abc2midi, seems to work fine, while support for Mup and PMW notation should be hard to do (they use the same program for rendering image and MIDI).
The most problematic one is Lilypond. It is not using any extra program or command line option for MIDI support, but adding a \midi{} block in input data instead before rendering. That means a special workflow for Lilypond MIDI support has to be designed, significantly different from support of any other notation.
