title: OpenCV: FFMPEG: tag 0x34363268/'h264' is not supported with codec
body: <p>After installed opencv like on Mac OS 10.13.6:</p>
  
  <pre><code>conda install -c conda-forge ffmpeg
  conda install -c conda-forge opencv
  </code></pre>
  
  <p>And using <code>fourcc = cv2.VideoWriter_fourcc('h', '2', '6', '4')</code> in videowriter</p>
  
  <p>I get error:</p>
  
  <pre><code>OpenCV: FFMPEG: tag 0x34363268/'h264' is not supported with codec id 27 and format 'mp4 / MP4 (MPEG-4 Part 14)'
  OpenCV: FFMPEG: fallback to use tag 0x31637661/'avc1'
  </code></pre>
  
  <p>How to fix it?</p>