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A high level midi library to play notes and interact with external midi devices.
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src changing to overtone project namespace and adding a bit more midi mes… Apr 4, 2010
project.clj changing to overtone project namespace and adding a bit more midi mes… Apr 4, 2010


A streamlined midi API for Clojure

midi-clj is being developed for Project Overtone, and it is meant to simplify the usage of midi devices and the midi system from within Clojure.

(use 'midi)

; Select midi input and output devices
; These functions bring up a GUI chooser window to select a midi port
(def keyboard (midi-in))
(def phat-synth (midi-out))

; Once you know the correct device names for your devices you can save the
; step of opening up the GUI chooser by putting a unique part of the name 
; as an argument to midi-in or midi-out.  The first device with a name that
; matches with lookup is returned.
(def ax (midi-in "axiom"))

; Connect ins and outs easily
(midi-route keyboard phat-synth)

; Trigger a note (note 40, velocity 100)
(midi-note-on phat-synth 40 100)
(Thread/sleep 500)
(midi-note-off phat-synth 0)

; Or the short-hand version to start and stop a note
(midi-note phat-synth 40 100 500)

; And the same thing with a sequence of notes
(midi-play phat-synth [40 47 40] [80 50 110] [250 500 250])

In Ubuntu Linux I use the snd-virmidi kernel module to provide software midi ports. USB midi devices should be pretty much plug and play.

Project Info:

Include in your project.clj like so:

[overtone/midi-clj "0.1"]

Source Repository

Downloads and the source repository can be found on GitHub:

Eventually there will be more documentation for this library, but in the meantime you can see it in use within the context of Project Overtone, located here:

Mailing List

For any questions, comments or patches, use the Overtone google group here:


  • Jeff Rose
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