Media Session API

The Media Session API provides a way to customize media notifications. It does this by providing metadata for display by the user agent of the media your web app is playing, and allows you to create event handlers, to define your own behaviors for a user-agent playback controls. The aim of this is allowing users to know what's playing, and to control it, without opening the specific page that launched it.

Media Session concepts and usage

The MediaMetadata interface lets a web site provide rich metadata to the platform UI for media that is playing. This metadata includes the title, artist (creator) name, album (collection), and artwork. The platform can show this metadata in media centers, notifications, device lockscreens, etc.

The MediaSession interface lets users control playback of media through user-agent defined interface elements. Interaction with these elements even trigger handlers in the web page, playing the media. Since multiple pages may be simultaneously using this API, the user agent is responsible for calling the correct page's event handlers. The user agent provides default behaviors, when no page-defined behavior is available.

Accessing the Media Session API

The primary interface for the Media Session API is the MediaSession interface. Rather than creating your own MediaSession instance, you access the API using the navigator.mediaSession property. For example, to set the current state of the media session to playing:

navigator.mediaSession.playbackState = "playing";

Interfaces

MediaMetadata

Allows a web page to provide rich media metadata, for display in a platform UI.

MediaSession

Allows a web page to provide custom behaviors, for standard media playback interactions.

Dictionaries

MediaImage

A MediaImage object contains information describing an image associated with the media. This might be a CD or DVD cover, a movie poster, a poster frame, or the like.

MediaPositionState

Used to contain information about the current playback position, playback speed, and overall media duration when calling the MediaSession method setPositionState() to establish the media's length, playback position, and playback speed.

MediaSessionActionDetails

Provides information needed in order to perform the action which has been requested, including the type of action to perform and any other information needed, such as seek distances or times.

Examples

The following example shows feature detection for the Media Session API. It then instantiates a metadata object for the session, and adds event handlers for the user control actions:

if ('mediaSession' in navigator) {
  navigator.mediaSession.metadata = new MediaMetadata({
    title: 'Unforgettable',
    artist: 'Nat King Cole',
    album: 'The Ultimate Collection (Remastered)',
    artwork: [
      { src: 'https://dummyimage.com/96x96',   sizes: '96x96',   type: 'image/png' },
      { src: 'https://dummyimage.com/128x128', sizes: '128x128', type: 'image/png' },
      { src: 'https://dummyimage.com/192x192', sizes: '192x192', type: 'image/png' },
      { src: 'https://dummyimage.com/256x256', sizes: '256x256', type: 'image/png' },
      { src: 'https://dummyimage.com/384x384', sizes: '384x384', type: 'image/png' },
      { src: 'https://dummyimage.com/512x512', sizes: '512x512', type: 'image/png' },
    ]
  });

  navigator.mediaSession.setActionHandler('play', function() { /* Code excerpted. */ });
  navigator.mediaSession.setActionHandler('pause', function() { /* Code excerpted. */ });
  navigator.mediaSession.setActionHandler('seekbackward', function() { /* Code excerpted. */ });
  navigator.mediaSession.setActionHandler('seekforward', function() { /* Code excerpted. */ });
  navigator.mediaSession.setActionHandler('previoustrack', function() { /* Code excerpted. */ });
  navigator.mediaSession.setActionHandler('nexttrack', function() { /* Code excerpted. */ });
}

Some user agents disable autoplay for media elements on mobile devices and require a user gesture to start media. The following example adds a pointerup event to an on-page play button, which is then used to kick off the media session code:

playButton.addEventListener('pointerup', function(event) {
  var audio = document.querySelector('audio');

  // User interacted with the page. Let's play audio...
  audio.play()
  .then(_ => { /* Set up media session controls, as shown above. */ })
  .catch(error => { console.log(error) });
});

Specifications

Browser compatibility