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 for the media your web app is playing.

It also provides action handlers that the browser can use to access platform media keys such as hardware keys found on keyboards, headsets, remote controls, and software keys found in notification areas and on lock screens of mobile devices. So you can seamlessly control web-provided media via your device, even when not looking at the web page.

The aim is to allow users to know what's playing and to control it, without needing to open the specific page that launched it. To be able to support the Media Session API, a browser first needs a mechanism by which to access and be controlled by the OS-level media controls (such as Firefox's MediaControl).

Media Session concepts and usage

The MediaMetadata interface lets a website 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 triggers action 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 action 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:

js

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.

Examples

Setting up action handlers for a music player

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

js

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", () => {
    /* Code excerpted. */
  });
  navigator.mediaSession.setActionHandler("pause", () => {
    /* Code excerpted. */
  });
  navigator.mediaSession.setActionHandler("stop", () => {
    /* Code excerpted. */
  });
  navigator.mediaSession.setActionHandler("seekbackward", () => {
    /* Code excerpted. */
  });
  navigator.mediaSession.setActionHandler("seekforward", () => {
    /* Code excerpted. */
  });
  navigator.mediaSession.setActionHandler("seekto", () => {
    /* Code excerpted. */
  });
  navigator.mediaSession.setActionHandler("previoustrack", () => {
    /* Code excerpted. */
  });
  navigator.mediaSession.setActionHandler("nexttrack", () => {
    /* Code excerpted. */
  });
  navigator.mediaSession.setActionHandler("skipad", () => {
    /* 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:

js

playButton.addEventListener("pointerup", (event) => {
  const 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.error(error);
    });
});

Using action handlers to control a slide presentation

The "previousslide" and "nextslide" action handlers can be used to handle moving forward and backward through a slide presentation, for example when the user puts their presentation into a Picture-in-Picture window, and presses the browser-supplied controls for navigating through slides.

js

try {
  navigator.mediaSession.setActionHandler("previousslide", () => {
    log('> User clicked "Previous Slide" icon.');
    if (slideNumber > 1) slideNumber--;
    updateSlide();
  });
} catch (error) {
  log('Warning! The "previousslide" media session action is not supported.');
}

try {
  navigator.mediaSession.setActionHandler("nextslide", () => {
    log('> User clicked "Next Slide" icon.');
    slideNumber++;
    updateSlide();
  });
} catch (error) {
  log('Warning! The "nextslide" media session action is not supported.');
}

See Presenting Slides / Media Session Sample for a working example.

Specifications

Specification
Media Session Standard
# the-mediasession-interface

Browser compatibility

BCD tables only load in the browser