midi-player-js/README.md

Midi parser & player engine for browser or Node. Works well with single or multitrack MIDI files.

# ♬ MidiPlayerJS
[![npm version](https://badge.fury.io/js/midi-player-js.svg)](https://badge.fury.io/js/midi-player-js)
[![CI](https://github.com/grimmdude/MidiPlayerJS/actions/workflows/node.js.yml/badge.svg)](https://github.com/grimmdude/MidiPlayerJS/actions/workflows/node.js.yml)

MidiPlayerJS is a JavaScript library which reads standard MIDI files and emits JSON events in real time.  This player does not generate any audio, but by attaching a handler to the event emitter you can trigger any code you like which could play audio, control visualizations, feed into a MIDI interface, etc.

## Demos
* [Neopixel Music](https://github.com/robertvorthman/neopixel-music) by robertvorthman @robertvorthman
* [Autocomposer](https://github.com/rjsalvadorr/autocomposer-js) by RJ Salvador @rjsalvadorr
* [Simple Browser Player](http://grimmdude.com/MidiPlayerJS/) by Garrett Grimm @grimmdude
* [Orchestra](https://lexcast.github.io/orchestra/) by Daniel Alejandro Cast @lexcast

## Getting Started
Using MidiPlayerJS is pretty simple.  Create a new player by instantiating `MidiPlayer.Player` with an event handler to be called for every MIDI event.  Then you can load and play a MIDI file.

```js
import MidiPlayer from 'midi-player-js';

// Initialize player and register event handler
const Player = new MidiPlayer.Player(function(event) {
	console.log(event);
});

// Load a MIDI file
Player.loadFile('./test.mid');
Player.play();
```
## Player Events
There are a handful of events on the `Player` object which you can subscribe to using the `Player.on()` method.  Some events pass data as the first argument of the callback as described below:

```js
Player.on('fileLoaded', function() {
    // Do something when file is loaded
});

Player.on('playing', function(currentTick) {
    // Do something while player is playing
    // (this is repeatedly triggered within the play loop)
});

Player.on('midiEvent', function(event) {
    // Do something when a MIDI event is fired.
    // (this is the same as passing a function to MidiPlayer.Player() when instantiating.
});

Player.on('endOfFile', function() {
    // Do something when end of the file has been reached.
});
```

Note that because of a common practice called "running status" many MIDI files may use `Note on` events with `0` velocity in place of `Note off` events.

## See Also

Need to generate MIDI files programmatically? Check out [MidiWriterJS](https://github.com/grimmdude/MidiWriterJS) — a JavaScript library for creating expressive multi-track MIDI files. Together they form a complete MIDI toolkit:

- **MidiPlayerJS** — parse and play MIDI files with real-time event callbacks
- **MidiWriterJS** — generate MIDI files programmatically

## Full API Documentation
[http://grimmdude.com/MidiPlayerJS/docs/](http://grimmdude.com/MidiPlayerJS/docs/)