title: Generate video thumbnail using ffmpeg; Grab from RTMP server
body: <p>I have research how to generate a video thumbnail user FFMPEG like so:</p>
  
  <p><code>ffmpeg -i myfile.flv -vcodec mjpeg -vframes 1 -an -f rawvideo -s 640x480 foo.jpg</code></p>
  
  <p>But how can I generate a thumbnail when the file is on another server? Specifically a RTMP server? for example: <code>rtmp://foo.rtmphost.com/videos</code> </p>