title: how to get the delay of ffmpeg?
body: <p>I'm using ffmpeg to do some work on a network like this:</p>
  <pre><code>RtmpServer1 -- FfmpegServer -- RtmpServer2
  </code></pre>
  <p>I put a 6mins.mp4 on RtmpServer1(10.10.1.1) and play it on RtmpServer2(10.10.2.2) by this instruction:</p>
  <pre><code>ffmpeg -i rtmp://10.10.1.1:1935/play/6mins.mp4 -vcodec copy -c:v libx264 -f flv  rtmp://10.10.2.2:1935/live
  </code></pre>
  <p>I would like to know is there a way to test the length of the time ffmpeg use to decode, compress and encode?(the duration from ffmpeg server get the data to the ffmpeg server send it out)</p>
  <p>I tried tcpdump to listen on the both two eth ports(one for get and one for send) of ffmpeg server. But I can't match RTMP packets by pairs(&quot;pairs&quot; means the packets containing the same data, one &quot;got&quot; packet matches one &quot;sent&quot; packet). I'd also like to know if there's a way to match the RTMP packets by their content(data).</p>