gistfile1.txt

<video controls="" autoplay="" width="320" height="240"></video>
<script>
var video = document.querySelector('video');

video.addEventListener('error', onVideoError);

window.MediaSource = window.MediaSource || window.WebKitMediaSource;

var mediaSource = new MediaSource();

video.src = window.URL.createObjectURL(mediaSource);

mediaSource.addEventListener('sourceopen', function(){
  window.video.pause();
  window.mediaSource.mode = 'sequence'
  window.sourceBuffer = window.mediaSource.addSourceBuffer('audio/webm; codecs="opus"');

  fileDownload('0.webm', function(ar) {
    var appendTime = 0
    sourceBuffer.timestampOffset = appendTime - 648/48000;
    sourceBuffer.appendWindowEnd = appendTime + 5;
    sourceBuffer.appendWindowStart = appendTime;
    window.sourceBuffer.appendBuffer(new Uint8Array(ar));

    fileDownload('1.webm', function(ar) {
      var appendTime = 5//window.sourceBuffer.buffered.end(0);
      sourceBuffer.timestampOffset = appendTime - 648/48000;
      sourceBuffer.appendWindowEnd = appendTime + 5;
      sourceBuffer.appendWindowStart = appendTime;
      window.sourceBuffer.appendBuffer(new Uint8Array(ar));

      fileDownload('2.webm', function(ar) {
        var appendTime = 10//window.sourceBuffer.buffered.end(0);
        sourceBuffer.timestampOffset = appendTime - 648/48000;
        sourceBuffer.appendWindowEnd = appendTime + 5;
        sourceBuffer.appendWindowStart = appendTime;
        window.sourceBuffer.appendBuffer(new Uint8Array(ar));
        window.video.play();
      });
    });
  });
});

function onVideoError() {
  var error = video.error
  switch (error.code) {
    case error.MEDIA_ERR_DECODE:
      console.error(`[MediaLoader] Error: Failed to decode media.`)
      break
    case error.MEDIA_ERR_SRC_NOT_SUPPORTED:
      console.error(`[MediaLoader] Error: Source is not supported.`)
      break
    case error.MEDIA_ERR_NETWORK:
      console.error(`[MediaLoader] Error: Network error.`)
      break
    case error.MEDIA_ERR_ABORTED:
      console.error(`[MediaLoader] Error: Aborted.`)
      break
  }
}

function fileDownload(url, cb) {
  var xhr = new XMLHttpRequest();
  xhr.open('GET', url, true);
  xhr.responseType = 'arraybuffer';
  xhr.send();
  xhr.onload = function(e) {
    cb(xhr.response);
  };
};
</script>