title: How to make mp4 from MediaStream in Chrome browser
body: <p><code>MediaRecorder.isTypeSupported('video/mp4')</code> is <code>false</code> in Chrome. So I found <code>MediaStreamRecorder</code> <a href="https://github.com/streamproc/MediaStreamRecorder" rel="nofollow noreferrer">https://github.com/streamproc/MediaStreamRecorder</a> then I did</p>
  
  <pre class="lang-js prettyprint-override"><code>var recorder = new MediaStreamRecorder(stream, {
    mimeType: 'video/mp4',
  });
  // also
  recorder.mimeType = 'video/mp4';
  </code></pre>
  
  <p>But the output is <code>webm</code> as I checked with <code>ffmpeg -i</code></p>
  
  <pre><code>Input #0, matroska,webm, from '/Users/otiai10/Downloads/example.mp4':
    Metadata:
      encoder         : Chrome
    Duration: N/A, start: 0.000000, bitrate: N/A
      Stream #0:0(eng): Video: vp8, yuv420p, 640x480, SAR 1:1 DAR 4:3, 30 fps, 30 tbr, 1k tbn, 1k tbc (default)
  </code></pre>
  
  <p>The video is playable in Chrome but NOT on QuickTime Player, in evidence.</p>
  
  <p><a href="https://github.com/streamproc/MediaStreamRecorder/issues/117" rel="nofollow noreferrer">Here</a> are more details and (not!) working example of this problem.</p>
  
  <p>It was said <a href="https://github.com/muaz-khan/Ffmpeg.js" rel="nofollow noreferrer">muaz-khan/Ffmpeg.js</a> can convert webm to mp4, but the file size matters.</p>
  
  <p>Is there any workaround to record and save as mp4?</p>