Many people are using Emacs for many music related tasks, be it editing csound files, lilypond files, or playing mp3:s with emms.
It would also be interesting to be able to use emacs as a soundtracker-like environment. That is, edit midi-data in the form of a text based piano roll, and also play it with a real-time updated cursor that highlight all notes currenly being played.
It is perhaps noteworthy that Emacs can open Midi devices directly using
(make-serial-process :speed nil ...)
and operate on them using the normal I/O operators also available for terminal processes.
midi.el in emacs.sources
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