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Instruments and MIDI mangemant tools for Overtone
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doc Adds Xolotl documentation Nov 9, 2015
resources Xolotl documentation Nov 3, 2015
src Typo fix Feb 5, 2016
.gitignore Git ignore error logs May 10, 2015
BUGS Bug 0012 discoverd Nov 6, 2015
CHANGELOG Update version changelog Feb 5, 2016
LICENSE Mostly documentation changes Mar 9, 2014 Minor typo changes Mar 10, 2014
project.clj Version bump to 0.4.0 Nov 9, 2015


Cadejo is a MIDI management tool for use with Overtone, Some of its features are:

  • Multitimberal
  • Arbitrary key splits and layering
  • Tuning tables for alternate scales
  • Mapping functions for MIDI velocity, continuous controllers and channel pressure.
  • Separate mono and polyphonic keymodes, additional keymodes may be implemented later.
  • Program banks


The Cadejo repo contains 4 full feature instruments:

  • ALGO - an 8 operator FM synthesizer.
  • Alias - a subtractive synthesizer with extensive modulation routing.
  • MASA - an organ roughly equivalent to the Hammond B3.
  • Combo - a simpler organ chiefly used for demonstration purposes.

Each instrument includes a program bank containing several program or 'patch' definitions.

Cadejo Structure

Cadejo uses a hierarchical tree structure with the general form

[midi-port] --> scene --> channels --> performance --> instrument

Each node has a set of properties in the form of key/value pairs and all nodes automatically inherit the properties of their parent. If a node defines a property also defined in one of its ancestors the local value shadows the parent's value and takes priority. As a concrete example each scene has the property :tuning-table which defaults to a standard 12-note tuning with MIDI key 69 producing A440. Any alternate tuning table defined at either the channel or performance level will take precedence over this default value.


A Scene is the root node for a Cadejo tree. It is always connected to a single MIDI input port and always has 16 child nodes corresponding to the 16 MIDI channels. A scene may also contain default properties for the local environment. Two such properties are automatically defined for each scene

  • :tuning-table - A standard 12 notes per octave scale with MIDI key 69 = A440
  • :velocity-map - A linear function which maps MIDI velocity values (0-127) to a normalized range of (0.0-1.0)


Each scene has 16 child nodes corresponding to the 16 MIDI channels. Typical properties defined at the channel level include pitch-bend range, channel-pressure maps, velocity maps, and MIDI continuous controller assignments. Each channel may have 0 or more performance child nodes. It is the combination of performance nodes under a channel which allow for key-splits and layering.


A performance may be viewed as a container which holds reference to the various SuperCollider synths, buses, banks and keymodes which define an instrument.


Cadejo has no requirements other then a working copy of Overtone.


Prior to first usage a MIDI port must be established by setting the value of midi-input-port in cadejo/demo.clj. Once the device has been set navigate to the main Cadejo folder and start a Clojure REPL. If all goes well Cadejo should bootstrap and after a few seconds be ready to play. As Cadejo loads several lines of text will be displayed. Once Cadejo is loaded it should display the text "Ready..."

The default demonstration program creates instruments on MIDI channels 0, 1, 2 and 3. All instruments have several programs changes available via MIDI program change messages. Program number 127 is special and produces a random patch.


The Alias instrument is very complex and capable of creating speaker
destroying sub-sonics, particularly when using the random program
generation feature. For the most part it behaves but please keep
monitor levels down until you know what it is doing.  

At some point it is hoped that a configuration file feature will be added. For the moment demo.clj doubles as the configuration file.


Preliminary documentation may be found in the cadejo/docs folder. Documentation for the Combo instrument doubles as an example of how to integrate Overtone instruments into a Cadejo context.


Cadejo contains a few known bugs. These are tracked in the file cadejo/BUGS.


Copyright © 2014 Steven Jones

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