README.md

node-easymidi

node-easymidi is a simple event-based MIDI messaging wrapper for node-midi.

Installation

Install with NPM:

npm install easymidi

Usage Overview

The module can interface with existing MIDI inputs/outputs or create virtual inputs/outputs. Here's a simple example to listen for note on events from an existing MIDI input:

const easymidi = require('easymidi');
const input = new easymidi.Input('MIDI Input Name');
input.on('noteon', function (msg) {
  // do something with msg
});

Here's an example of sending a note on message to an existing MIDI output:

const easymidi = require('easymidi');
const output = new easymidi.Output('MIDI Output Name');
output.send('noteon', {
  note: 64,
  velocity: 127,
  channel: 3
});

The Input and Output objects are EventEmitters and you can use the EventEmitter functions such as once(), removeListener(), and removeAllListeners() as well.

Virtual Devices

Virtual devices can be created by passing a true argument to the Input or Output constructors:

const virtualInput = new easymidi.Input('Virtual input name', true);
const virtualOutput = new easymidi.Output('Virtual output name', true);

Device Lists

You can get an array of existing MIDI input or output names using the getInputs() and getOutputs functions:

const inputs = easymidi.getInputs();
const outputs = easymidi.getOutputs();

Closing Devices

When you're finished with a MIDI device you can close() it:

const input = new easymidi.Input('My input', true);
input.close();

const output = new easymidi.Output('My output', true);
output.close();

Message Reference

The following table describes the MIDI message types that are supported and the parameters of each:

Type	Parameter	Parameter	Parameter
noteon	note [0-127]	velocity [0-127]	channel [0-15]
noteoff	note [0-127]	velocity [0-127]	channel [0-15]
poly aftertouch	note [0-127]	velocity [0-127]	channel [0-15]
cc	controller [0-127]	value [0-127]	channel [0-15]
program	number [0-127]		channel [0-15]
channel aftertouch	pressure [0-127]		channel [0-15]
pitch	value [0-16384]		channel [0-15]
position	value [0-16384]
mtc	type [0-7]	value [0-15]
select	song [0-127]
clock
start
continue
stop
activesense
reset
sysex	bytes (variable length array)

Examples

Receive a noteon message:

input.on('noteon', function (params) {
  // params = {note: ..., velocity: ..., channel: ...}
});

Send a control change message:

output.send('cc', {
  controller: 37,
  value: 80,
  channel: 0
})

Listen for midi clock messages:

input.on('clock', function () {
  // do something on every clock tick
});

Send a sysex message.
Throws an error if array does not start with 0xf0 (240) and end with 0xf7 (247).

output.send('sysex',[240, 126, 1, 6, 1, 247]);

See the example programs for more examples.