title: How to Sync multiple IP cameras
body: <p>Is it possible for a video player to play live video from two IP Cameras for the same scene in sync?
  Assumption: 
      Both cameras output RTSP H.264
      Clocks on the two camera are always accurate. 
      Of course both cameras run RTCP server.
  I have searched the internet for long and could not find a certain answer.</p>
  
  <p>My thoughts so far:
  Since the two RTCP servers map the RTP timestamps from the two cameras to UTC time, I can sync after unpacking RTP so that the element stream are synced when pushed to decoder.
  Is this correct?</p>