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:

`javascript
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:

`javascript
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:

`javascript
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:

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

Closing Devices


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

`javascript
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] |
| 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:

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

Send a control change message:

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

Listen for midi clock messages:

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

See the example programs for more examples.