Parser for midi received from teenage engineering's OP-Z sequencer.
Decodes events from the Web MIDI API. Also refer to Mozilla's documentation
TEENAGE ENGINEERING OPZ MIDI DOCS
Assumes you have an OP-Z.
Useful just as a reference to get started.
npm install opzjs
Option 1: Download opz.js from dist folder.
<script src="[path to opz.js file]><script>
Option 2: Build distribution.
- Clone repo
npm run build- Copy new file saved in dist
Note: run Make install if you're missing js-yaml
<script src="[path to opz.js file]><script>
decode(data): data is an array of integer values (ex. [252], [123, 45, 0], etc.)
Returns an Object.
{
track: ...,
action: ...,
velocity: ...,
value: ...
}
velocity (data): data is an array of integer values (ex. [252], [123,45,0], etc.)
Returns an Integer between 0 to 127.
| field | value |
|---|---|
| track | kick, snare, perc, sample, bass, lead, arp, chord, fx1, fx2, tape, master, perform, module, lights, motion |
| action | keys, dial, pitch bend |
| velocity | 0-127 |
| value (action=key) | { value: 101 note: F } |
| value (action=dial) | { dial: 0, dialColor: "green", page: 3, pageColor: "yellow" } |
| value (action=pitch_bend) | { absolute: 0, // 0 - 128 relative: 64, // 0 - 128 } |
| field | value |
|---|---|
| track | clock, start, stop |
| action | clock, start, stop |
| velocity | -1 |
| value | {} |
The following buttons do not send midi. However, a number of them can be "inferred" through the context of the keyboard key or the dials. Example, pressing the kick track button on it's own will not send midi but pressing a keyboard key while using the kick track will (and then there's enough information to glean that it was a kick).
- track buttons
- play
- stop
- +/- octave shift
- project, mixer, tempo, screen
When the OP-Z is playing and the stop key is pressed a series of midi notes are sent to quiet the dials. As it's unclear which page (or color) these messages apply to, they've been labeled as "kill".
Example:
{
track: "kick",
action: "dial",
velocity: 0,
value: {
dial: 2
dialColor: "kill"
page: 30
pageColor: "kill"
}
}- Plug OP-Z into computer
- Ensure "MIDI OUT ENABLE" is ON (use the app or refer to teenage engineering docs)
The following example uses justinlatimer's node-midi library. Comments have been removed. Please refer to the docs for more information.
const midi = require('midi');
const opz = require('opzjs');
// Set up a new input.
const input = new midi.Input();
// Count the available input ports.
console.log("port count: ", input.getPortCount());
// Get the name of a specified input port.
if (input.getPortCount() > 0){
console.log(input.getPortName(0));
// Configure a callback.
input.on('message', (deltaTime, message) => {
console.log(`m: ${message} d: ${deltaTime}`);
console.log(opz.decode(message)); // <--------- OPZ.
/*
{
track: "kick",
action: "keys",
velocity: 100,
value: {
value: 101,
note: "F"
}
}
*/
});
// Open the first available input port.
input.openPort(0);
// Close the port when done.
setTimeout(function() {
input.closePort();
}, 100000);
}- Setup/listen for a midi input
The following listens for midi input from ALL input sources. If you want to specifically filter midi from the OP-Z then look into midiAccess.inputs or find an example online.
Assumes you've put opz.js in the same folder.
<script src="/opz.js"></script>
<script type="text/javascript">
if (navigator.requestMIDIAccess) {
console.log('This browser supports WebMIDI!');
} else {
console.log('WebMIDI is not supported in this browser.');
}
navigator.requestMIDIAccess()
.then(onMIDISuccess, onMIDIFailure);
function onMIDIFailure() {
console.log('Could not access your MIDI devices.');
}
function onMIDISuccess(midiAccess) {
// midiAccess.data is an array of values [255], [120,0,100], etc.
const input = OPZ.decode(midiAccess.data)
/*
Example:
input = {
track: "kick",
action: "keys",
velocity: 100,
value: {
value: 101,
note: "F"
}
}
*/
}
</script>Step components are not sent explicitly as midi notes. Though, for example, in the case of trippling a note (x2 component) three notes are sent.
Contributions or suggestions are welcome.
OP-Z photo from teenage engineering's website.
MIT