title: ffmpeg blackdetect, start_black value to mkv chapter?
body: <p>I'm trying to do automatic detect chapter with blackdetect with ffmpeg.</p>
  
  <p>When I use blackdetect I get result but what is the result? Its not frames? Also. Is it possible to do a script/bat-file (for windows 10, powershell or cmd) to convert the result to a "mkv xml-file" so It can be imported with mkvtoolnix?</p>
  
  <pre><code>ffmpeg -i "movie.mp4" -vf blackdetect=d=0.232:pix_th=0.1 -an -f null - 2&gt;&amp;1 | findstr black_duration &gt; output.txt
  </code></pre>
  
  <p>result: </p>
  
  <pre><code> black_start:2457.04 black_end:2460.04 black_duration:3
   black_start:3149.46 black_end:3152.88 black_duration:3.41667
   black_start:3265.62 black_end:3268.83 black_duration:3.20833
   black_start:3381.42 black_end:3381.92 black_duration:0.5
   black_start:3386.88 black_end:3387.38 black_duration:0.5
   black_start:3390.83 black_end:3391.33 black_duration:0.5
   black_start:3824.29 black_end:3824.58 black_duration:0.291667
   black_start:3832.71 black_end:3833.08 black_duration:0.375
   black_start:3916.29 black_end:3920.29 black_duration:4
  </code></pre>