html-midi-player

<midi-player> and <midi-visualizer> HTML elements powered by @magenta/music (Magenta.js), fully stylable and scriptable.

See a demo here.

Getting started

1. Add the necessary scripts to your page:

   <script src="https://cdn.jsdelivr.net/combine/npm/tone@13,npm/@magenta/music@1/es6/core.js,npm/focus-visible@5,npm/html-midi-player@1"></script>

2. Add a player and a visualizer:

   <midi-player
     src="https://magenta.github.io/magenta-js/music/demos/melody.mid"
     sound-font visualizer="#myVisualizer">
   </midi-player>
   <midi-visualizer type="piano-roll" id="myVisualizer"></midi-visualizer>

That's it!

Installing from NPM

You can also add the package to your project from NPM, e.g. npm install --save html-midi-player or yarn add html-midi-player. Then you can either import 'html-midi-player' in your JavaScript code, or add the node_modules/html-midi-player/dist/midi-player.min.js bundle directly to your page.

You should also add the focus-visible polyfill to enable outlines on keyboard focus.

API basics

See also the API reference for both elements: midi-player, midi-visualizer.

src and noteSequence

Both midi-player and midi-visualizer support two different ways of specifying the input file:

• By setting the src attribute to a MIDI file URL, e.g.:

  <midi-player src="twinkle-twinkle.mid"></midi-player>

  player.src = "twinkle-twinkle.mid";

• By assigning a Magenta NoteSequence to the noteSequence property, e.g.:

  player.noteSequence = TWINKLE_TWINKLE;

SoundFonts

By default, the player will use a simple oscillator synth. To use a SoundFont, add the sound-font attribute:

<midi-player sound-font></midi-player>  <!-- default SoundFont (same as below) -->
<midi-player sound-font="https://storage.googleapis.com/magentadata/js/soundfonts/sgm_plus"></midi-player>

player.soundFont = null;  // no SoundFont
player.soundFont = '';    // default SoundFont (same as below)
player.soundFont = 'https://storage.googleapis.com/magentadata/js/soundfonts/sgm_plus';

See the Magenta.js docs for a list of available SoundFonts.

Visualizer settings

The visualizer type is specified via the type attribute. Three visualizer types are supported: piano-roll, waterfall and staff.

Each visualizer type has a set of settings that can be specified using the config attribute, e.g.:

visualizer.config = {
  noteHeight: 4,
  pixelsPerTimeStep: 60,
  minPitch: 30
};

The settings are documented in the Magenta.js docs.

Binding visualizers

A player supports binding one or more visualizers to it using the visualizer attribute (a selector) or the addVisualizer method:

<midi-player visualizer="#myVisualizer, #myOtherVisualizer"></midi-player>

player.addVisualizer(document.getElementById('myVisualizer'));
player.addVisualizer(document.getElementById('myOtherVisualizer'));

The visualizer only gets updated while the player is playing, which allows a single visualizer to be bound to multiple players.

Limitations

• Only one player can play at a time. Starting a player will stop any other player which is currently playing. (#1)
• Seeking only works while playing. (#2)
• Playback position only gets updated on note onsets. This may cause the player to appear stuck.