MediaSource: addSourceBuffer() method

{{APIRef("Media Source Extensions")}}{{AvailableInWorkers("window_and_dedicated")}}

The addSourceBuffer() method of the {{domxref("MediaSource")}} interface creates a new {{domxref("SourceBuffer")}} of the given {{Glossary("MIME type")}} and adds it to the MediaSource's {{domxref("MediaSource.sourceBuffers", "sourceBuffers")}} list. The new SourceBuffer is also returned.

Syntax

addSourceBuffer(mimeType)

Parameters

• mimeType
  • : A string specifying the MIME type of the {{domxref("SourceBuffer")}} to create and add to the {{domxref("MediaSource")}}.

Return value

A {{domxref("SourceBuffer")}} object representing the new source buffer that has been created and added to the media source.

Exceptions

• InvalidAccessError {{domxref("DOMException")}}
  • : Thrown if the value specified for mimeType is an empty string rather than a valid MIME type.
• InvalidStateError {{domxref("DOMException")}}
  • : Thrown if the {{domxref("MediaSource")}} is not in the "open" {{domxref("MediaSource.readyState", "readyState")}}.
• NotSupportedError {{domxref("DOMException")}}
  • : Thrown if the specified mimeType isn't supported by the {{Glossary("user agent")}}, or is not compatible with the MIME types of other {{domxref("SourceBuffer")}} objects that are already included in the media source's {{domxref("MediaSource.sourceBuffers", "sourceBuffers")}} list.
• {{domxref("QuotaExceededError")}}
  • : Thrown if the user agent can't handle any more SourceBuffer objects, or creating a new SourceBuffer using the given mimeType would result in an unsupported configuration of SourceBuffers.

Examples

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.

const assetURL = "frag_bunny.mp4";
// Need to be specific for Blink regarding codecs
// ./mp4info frag_bunny.mp4 | grep Codec
const mimeCodec = 'video/mp4; codecs="avc1.42E01E, mp4a.40.2"';
const mediaSource = getMediaSource();

if ("MediaSource" in window && MediaSource.isTypeSupported(mimeCodec)) {
  console.log(mediaSource.readyState); // closed
  mediaSource.addEventListener("sourceopen", sourceOpen);
  video.src = URL.createObjectURL(mediaSource);
} 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);
  });
}

Specifications

{{Specifications}}

Browser compatibility

{{Compat}}

See also

• {{domxref("SourceBuffer")}}
• {{domxref("SourceBufferList")}}