html-midi-player

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

Works in Jupyter notebooks, Colab, and Weights & Biases thanks to the midi-player Python package by @drscotthawley.

• Simple demo
• Advanced demo
• Website [source] with MIDI file upload

Notable websites that use html-midi-player include abcnotation.com, Musical Nexus and demo websites for music generation models: piano infilling, stochastic positional encoding.

If you use html-midi-player on your website, please consider linking back to the repository.

Getting started

1. Add the necessary scripts to your page:

   <script src="https://cdn.jsdelivr.net/combine/npm/[email protected],npm/@magenta/[email protected]/es6/core.js,npm/focus-visible@5,npm/[email protected]"></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!

Besides jsDelivr, the bundle is also available from cdnjs.

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 (as an ES Module), or
• add the node_modules/html-midi-player/dist/midi-player.min.js bundle directly to your page, along with the dependencies (node_modules/tone/build/Tone.js, node_modules/@magenta/music/es6/core.js; note that these need to go before html-midi-player).

In both cases, you should also add the focus-visible polyfill to enable outlines on keyboard focus.

API basics

The basic features of html-midi-player are explained below. Wherever both HTML and JavaScript examples are given, they are equivalent. In the JavaScript examples, player and visualizer refer to the corresponding custom element objects, which can be obtained using standard DOM methods like document.getElementById('#myPlayer') or document.querySelectorAll('midi-player'), for example.

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;

  To obtain a NoteSequence, you can use Magenta functions like urlToNoteSequence() (see FAQ).

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.

Looping

To make the player loop, use the loop attribute:

<midi-player loop></midi-player>

player.loop = true;

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 (only from JavaScript), 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.

Events

The player supports listening to different kinds of events using the player.addEventListener() method. See the API reference for the available event types.

FAQ

Here are some frequently asked questions about html-midi-player. Make sure to also check discussions and issues to see if your question is answered there.

Why is my MIDI file not loading?

Please make sure that you provide a valid HTTP(S) URL, either absolute (beginning with https:// or http://) or relative with respect to your HTML file (if hosted on the same server).

Local files most likely will not work, as most browsers block requests to local files. To test the MIDI player locally, you will need to start an HTTP server to host your MIDI file; see for example this tutorial for easy ways to do that.

To diagnose why the MIDI file is not loading, hover over the error icon to see the error; if the message is "Bad MIDI file. Expected 'MHdr'", it means either your file is not a valid MIDI file, or the server cannot find your file and is serving an error page instead. To see the file actually being served, open your browser's Developer Tools, go to the Network tab, reload the page, then find the name of your file in the list.

How can I use custom samples?

The player supports "SoundFonts" in a special format designed by Magenta. If you want to use a .sf2 file, it will not work out of the box, but it is possible to convert it with some effort. See this discussion thread and especially this answer, which proposes a conversion script.

How do I create and manipulate NoteSequences?

The Magenta.js core and core/sequences modules define functions for loading and manipulating NoteSequences. To load a MIDI file as a NoteSequence, use the urlToNoteSequence() function. Other useful functions are clone(), trim() and concatenate().

If you are using the provided bundle as suggested above, then the core module will be available simply as core, so you will be able to call e.g. core.urlToNoteSequence() or core.sequences.clone() from your code.

Can you implement feature X or fix issue Y?

This library is a relatively thin wrapper around Magenta.js, which provides all of the MIDI loading, synthesis and visualization functionality. This means it inherits most of its limitations. If you found an issue, try to check if Magenta.js is also affected, e.g. using this or this demo (click Load MIDI File to upload your own file). If the issue is still there, then this is most likely a Magenta.js issue and cannot be fixed here (although a workaround may be possible). Otherwise, feel free to open an issue (or even better, a pull request) here, but please check for existing issues and discussions first.

Limitations

• Only one player can play at a time. Starting a player will stop any other player which is currently playing. (#1) This can actually be a benefit in many cases.
• Playback position only gets updated on note onsets. This may cause the player to appear stuck.