title: getting AVFrame pts value
body: <ol>
  <li>I have a AVStream of Video from FormatContext. [ avstream ]</li>
  <li>Read Packet</li>
  <li>Decode packet if it is from video.</li>
  <li><p>Now Display the following.</p>
  
  <pre><code>Packet DTS -&gt;  7200.00    [ from packet ]
  Frame PTS   -&gt; -9223372036854775808.000000
  stream time_base -&gt;  0.000011
  Offset                    -&gt;  0.080000    [ pts * time_base ]
  </code></pre></li>
  </ol>
  
  <p>code:</p>
  
  <pre class="lang-c++ prettyprint-override"><code>double pts = (double) packet.dts;
  printf (" dts of packet %f , Frame pts:  %f, timeBase %f Offset: %f ",
      pts,
      (double)pFrame-&gt;pts, 
      av_q2d (avstream-&gt;time_base) , 
      pts
  *av_q2d(avstream-&gt;time_base));
  </code></pre>
  
  <ol>
  <li>Why is Frame pts negative ? Is it expected behavior ?</li>
  <li>Do I need to consider Frame pts from packet DTS [ ie: frame pts = packet
  dts ]</li>
  </ol>