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:

var easymidi = require('easymidi');
var 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:

var easymidi = require('easymidi');
var 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:

var virtualInput = new easymidi.Input('Virtual input name', true);
var 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:

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

Closing Devices

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

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

var 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]
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 pressure	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 [array bookended by 0xF0 and 0xF7]

NON-MIDI MESSAGES

Type	Parameter	Parameter	Parameter
message	bytes [variable length byte array]	for receiving or sending any array of bytes
smpte	smpte [hh:mm:ss.ff]	frameRate [24 or 25 or 29.97 or 30]

Examples

Receive a noteon message:

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

Receive an mtc message formatted to smpte timecode:

input.on('smpte', function (params) {
  // params = {smpte: hh:mm:ss.ff, frameRate: 24 | 25 | 29.97 | 30}
});

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', {
  bytes: [240, 126, 1, 6, 1, 247]
});

See the example programs for more examples.