title: Convert videos to webm via ffmpeg faster
body: <p>I am using the following params via ffmpeg to convert videos to webm format:</p>
  
  <pre><code>-c:v libvpx -qmin 0 -qmax 50 -crf 4 -b:v 2M -c:a libvorbis -q:a 10
  </code></pre>
  
  <p>However it takes lot of time (more than 5 minutes) just to convert 5 MB video. Can I write some other params to make the conversion fast?</p>