testold.html


<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8"/>
  </head>
  <body>
    <video controls></video>
	<script src=//cdnjs.cloudflare.com/ajax/libs/seedrandom/2.3.10/seedrandom.min.js></script>
    <script>
	  Math.seedrandom('hello.');
	  var buffer = null;;
	  var sourceBuffer;
      var video = document.querySelector('video');
	  var mediaSource;
	  var fuzzed;
	  var i = 0;
	  var val = 0;
	  var crashes = [];
	  
	  function fuzz() {
		var buf = buffer.slice(0);
		var view = new DataView(buf);
		i++;
		val = 0;
		view.setUint8(i, val);
		return buf;
	  }
	  
	  function setup() {
	        if ('MediaSource' in window && MediaSource.isTypeSupported(mimeCodec)) {
				mediaSource = new MediaSource;
				video.src = URL.createObjectURL(mediaSource);
				mediaSource.addEventListener('sourceopen', sourceOpen);
			  } else {
				console.error('Unsupported MIME type or codec: ', mimeCodec);
			  }
	  }

      var assetURL = 'out.mp4';
      // ./mp4info frag_bunny.mp4 | grep Codec
      var mimeCodec = 'video/mp4; codecs="avc1.42c01e"';
	  setup();


      function sourceOpen (_) {
		var mediaSource = this;
		mediaSource.removeEventListener('sourceopen', sourceOpen);
		sourceBuffer = mediaSource.addSourceBuffer(mimeCodec);
		
		if(buffer === null) {
			fetchAB(assetURL, function (buf) {
			  sourceBuffer.addEventListener('updateend', function (_) {
				if(sourceBuffer.buffered.length == 0) {
					try {
						fuzzed = fuzz();
						sourceBuffer.appendBuffer(fuzzed);
					} catch(e) {
						console.log("Crashed on " + i + " to " + val);
						crashes.push([i, val]);
						if(crashes.length < 10) {
							setTimeout(setup, 1000);
						} else {
							document.body.innerHTML = "<pre>" + JSON.stringify(crashes, undefined, 2) + "</pre>";
						}
					}
				} else {
					try {
						mediaSource.endOfStream();
						//success();
					} catch(e) {
						//failure();
					}
					sourceBuffer.remove(0, 1000);
				}
				//video.play();
			  });
			  buffer = buf;
			  fuzzed = buf;
			  sourceBuffer.appendBuffer(buf);
			});
		  }
      };

      function fetchAB (url, cb) {
        var xhr = new XMLHttpRequest;
        xhr.open('get', url);
        xhr.responseType = 'arraybuffer';
        xhr.onload = function () {
          cb(xhr.response);
        };
        xhr.send();
      };
    </script>
  </body>
</html>