title: Speed up part of video using ffmpeg
body: <p>I'm recording screencasts and some part of the recorded screencasts I would like to speed up using a command line tool like ffmpeg.</p>
  
  <p>I know that it is possible to use ffmpeg to speed up an entire video with a command like (<a href="https://trac.ffmpeg.org/wiki/How%20to%20speed%20up%20/%20slow%20down%20a%20video">source</a>)</p>
  
  <pre><code>ffmpeg -i input.mkv -filter:v "setpts=0.5*PTS" output.mkv
  </code></pre>
  
  <p>Is it possible to only apply the speedup in certain regions in the video. Eg. from 10 to 15 seconds and again from 50 to 60 seconds? Something similar seems to be possible using the program <a href="http://slowmovideo.granjow.net/index.html">slowmoVideo</a>.</p>