title: How can I receive, parse RTP packets from DVR with php? (RTSP streaming)
body: <p>So my goal is to able to receive and interpret rtp stream from Digital Video Recorder(DVR).
  My RTSP initial tcp messages and responses are the following:</p>
  
  <pre><code>OPTIONS:
  
  RTSP/1.0 200 OK
  CSeq: 1
  Keep-Alive: timeout=10, max=1000
  Public: DESCRIBE, SETUP, TEARDOWN, PLAY, PAUSE, SET_PARAMETER
  Connection: Keep-Alive
  
  DESCRIBE:
  
  RTSP/1.0 200 OK
  CSeq: 1
  Content-Base: rtsp://192.168.0.99:554/live/mpeg4/
  Content-Type: application/sdp
  Content-Length: 225
  
  v=0
  o=- 1 1 IN IP4 127.0.0.1
  s=Test
  a=type:broadcast
  t=0 0
  c=IN IP4 0.0.0.0
  m=video 0 RTP/AVP 96
  a=rtpmap:96 MP4V-ES/90000
  a=fmtp:96 profile-level-id=3;config=00000100000001200086C4007B0C581120518F
  a=control:track0
  
  SETUP:
  
  RTSP/1.0 200 OK
  CSeq: 3
  Transport: RTP/AVP;unicast;client_port=6970-6971;server_port=58132-58133
  Session: 53A2D8BBA38F6D61979B8C323CB4A1
  
  PLAY:
  
  RTSP/1.0 200 OK
  CSeq: 4
  Session: 53A2D8BBA38F6D61979B8C323CB4A1
  Range: npt=now-
  RTP-Info: url=rtsp://192.168.0.99:554/live/mpeg4/track0;seq=58938;rtptime=388948125
  </code></pre>
  
  <p>After this successfufl initial steps the DVR should enable bitstream via RTP protocol but in the wireshark I don't see any rtp messages (filter:rtp)</p>
  
  <p>How can I receive and interpret rtp stream with php? 
  Furthermore I should be able to get images from given time intervals.
  I would appreciate if you could give some ideas.</p>