title: Extract a thumbnail from a specific video frame
body: <p>Given a specific frame I need to extract an image (a thumbnail) from a video using ffmpeg.</p>
  
  <p>E.g. I can do:</p>
  
  <pre><code>ffmpeg -i test.mp4 -ss 00:01:14.35 -vframes 1 out2.png
  </code></pre>
  
  <p>I can extract an image from a specific time (00:01:14.35), but what I need is to extract an image from a specific frame.</p>