Chrome Version       : 64.0.3274.0
OS Version: 10150.0.0

What steps will reproduce the problem?
1. Go to https://beaufortfrancois.github.io/sandbox/media/web-worker/
2. Open DevTools

What is the expected result?
I should see only one line:
1. Append shared array buffer...

What happens instead of that?
I see 3 lines:
1. Append shared array buffer...
2. Append view on shared array buffer...
3. Append a clone of the view on shared array buffer...

That's because sourceBuffer.appendBuffer doesn't handle shared array buffers and typed arrays on shared array buffers:


  const worker = new Worker('worker.js');
  const sharedBuffer = new SharedArrayBuffer(812);
  const view = new Uint8Array(sharedBuffer);

  worker.addEventListener('message', event => {
    const sourceBuffer = mediaSource.sourceBuffers[0];
    
    try {
      console.log('1. Append shared array buffer...');
      sourceBuffer.appendBuffer(sharedBuffer);
      return;
    } catch(e) {}

    try {
      console.log('2. Append view on shared array buffer...');
      sourceBuffer.appendBuffer(view);
      return;
    } catch(e) {}

    try {
      console.log('3. Append a clone of the view on shared array buffer...');
      sourceBuffer.appendBuffer(view.slice(0));
      return;
    } catch(e) {}

  });
  

It would be nice to handle those s that we could use web workers to offload fetch events instead of polluting UI thread with these calls.