title: 'audio/wav' mime type not supported by MSE SouceBuffer object, but audio src attribute pointing at .wav plays just fine
body: <p>I'm trying create a SourceBuffer from the W3 Media Source Extension API with Mime type 'audio/wav' like so:</p>
  
  <pre><code>let sourceBuffer = mediaSource.addSourceBuffer('audio/wav');
  </code></pre>
  
  <p>However I get a "NotSupportedError":</p>
  
  <p>Failed to execute 'addSourceBuffer' on 'MediaSource': The type provided ('audio/wav') is unsupported.</p>
  
  <p>Also, running the following:</p>
  
  <pre><code>MediaSource.isTypeSupported('audio/wav');
  </code></pre>
  
  <p>in the browser console returns false for both recent versions of firefox and chrome.</p>
  
  <p>If I just set the src of the audio tag to the url of the .wav, everything works fine. It's only when I use a SourceBuffer that I get file type support issues.  What DOMString do I need to specify to addSourceBuffer() to have it accept a PCM encoded .wav file?   </p>
  
  <p>I'm using Chrome 72 and firefox 68</p>