title: Is possible to know how many AVPackets for one AVFrame ?
body: <p>Is possible to know how many AVPackets for one AVFrame ? </p>
  
  <p>I would like to implement a function that user can play video in reverse way.</p>
  
  <p>I don't want to put temp datas in local file in some reasons so I would like to implement it via AVPacket directly.</p>
  
  <p>I found that in Audio, every pts of AVPacket is equal to dts of AVPacket.</p>
  
  <p>and I can reverse the AVPacket, put AVPacket to decode from last one to first one,</p>
  
  <p>and then I got the AVFrame.</p>
  
  <p>but in Video is difference, have no idea how to implement it.</p>
  
  <p>Is possible to calculate exactly AVPacket for one AVFrame ?</p>