MediaSource: readyState property

Limited availability

This feature is not Baseline because it does not work in some of the most widely-used browsers.

Note: This feature is available in Dedicated Web Workers.

The readyState read-only property of the MediaSource interface returns an enum representing the state of the current MediaSource. The three possible values are:

closed: The source is not currently attached to a media element.
open: The source is attached to a media element and ready to receive SourceBuffer objects.
ended: The source is attached to a media element but the stream has been ended via a call to MediaSource.endOfStream().

The following snippet is from an example written by Nick Desaulniers (view the full demo live, or download the source for further investigation). The function getMediaSource(), which is not defined here, returns a MediaSource.

let mediaSource;

if ("MediaSource" in window && MediaSource.isTypeSupported(mimeCodec)) {
  mediaSource = getMediaSource();
  console.log(mediaSource.readyState); // closed
  video.src = URL.createObjectURL(mediaSource);
  mediaSource.addEventListener("sourceopen", sourceOpen);
} else {
  console.error("Unsupported MIME type or codec: ", mimeCodec);
}

function sourceOpen() {
  console.log(this.readyState); // open
  const sourceBuffer = mediaSource.addSourceBuffer(mimeCodec);
  fetchAB(assetURL, (buf) => {
    sourceBuffer.addEventListener("updateend", () => {
      mediaSource.endOfStream();
      video.play();
      console.log(mediaSource.readyState); // ended
    });
    sourceBuffer.appendBuffer(buf);
  });
}