title: ffprobe - getting video info from file chunk
body: <p>On my site users can upload videos, which are encrypted on the fly and stored on another server. I want to store video bitrate, frame rate etc., but I have not direct access to them and I can not just use the following command:</p>
  
  <pre><code>ffprobe -show_streams -i file.mp4
  </code></pre>
  
  <p>I tried saving last chunk on my server, which contain moov atom, but ffprobe is outputting:</p>
  
  <pre><code>Format mov,mp4,m4a,3gp,3g2,mj2 detected only with low score of 1, misdetection possible!
  moov atom not found
  C:\file.mp4: Invalid data found when processing input
  </code></pre>
  
  <p>I checked and truncating at least one byte cause this, although moov atom is intact. </p>
  
  <p>What is the proper way to get video metadata from file fragment containg moov atom? What about getting informations from piece of mdata atom?</p>