MediaSource: sourceopen event

Available in workers

The sourceopen event is fired when a MediaSource object’s readyState changes to "open". This indicates that the MediaSource is ready to receive data from SourceBuffer objects. This can occur either when the MediaSource object is first attached to a media element or when the readyState changes from "ended" back to "open".

Syntax

Use the event name in methods like addEventListener(), or set an event handler property.

addEventListener("sourceopen", (event) => {});

onsourceopen = (event) => {};

Event type

A generic Event.

Examples

Handling the sourceopen event

This example sets up a MediaSource, connects it to a video element, and listens for the sourceopen event. When the event fires, it adds a SourceBuffer to handle the video data, fetches the data, appends it to the buffer, and finally revokes the object URL when the source ends.

const video = document.getElementById("myVideo");
const mediaSource = new MediaSource();

video.src = URL.createObjectURL(mediaSource);

mediaSource.addEventListener("sourceopen", (event) => {
  console.log("MediaSource sourceopen:", event);
  // Add source buffers and begin adding media data.
  const sourceBuffer = mediaSource.addSourceBuffer(
    'video/mp4; codecs="avc1.42E01E"',
  );
  fetch("video-data.mp4")
    .then((response) => response.arrayBuffer())
    .then((data) => {
      sourceBuffer.appendBuffer(data);
    });
});

mediaSource.addEventListener("sourceended", () => {
  URL.revokeObjectURL(video.src);
});

Specifications

Browser compatibility