MediaSource: sourceBuffers プロパティ

const mediaSource = getMediaSource();
function sourceOpen() {
  console.log(this.readyState); // open
  const sourceBuffer = mediaSource.addSourceBuffer(mimeCodec);
  fetchAB(assetURL, (buf) => {
    sourceBuffer.addEventListener("updateend", () => {
      mediaSource.endOfStream();
      console.log(mediaSource.sourceBuffers); // 上で追加されたソースバッファーが含まれます
      video.play();
      console.log(mediaSource.readyState); // ended
    });
    sourceBuffer.appendBuffer(buf);
  });
}
// …