rtsp报文

客户端请求：
OPTIONS rtsp://172.29.180.26:8554/live RTSP/1.0
CSeq: 2
User-Agent: LibVLC/3.0.18 (LIVE555 Streaming Media v2016.11.28)

服务端响应：
RTSP/1.0 200 OK
CSeq: 2
Public: OPTIONS, DESCRIBE, SETUP, TEARDOWN, PLAY

客户端请求：
DESCRIBE rtsp://172.29.180.26:8554/live RTSP/1.0
CSeq: 3
User-Agent: LibVLC/3.0.18 (LIVE555 Streaming Media v2016.11.28)
Accept: application/sdp

服务端响应：
RTSP/1.0 200 OK
CSeq: 3
Content-Length: 181
Content-Type: application/sdp

v=0
o=- 91701500474 1 IN IP4 172.29.180.26
t=0 0
a=control:*
a=type:broadcast
m=video 0 RTP/AVP 96
c=IN IP4 0.0.0.0
a=rtpmap:96 H264/90000
a=framerate:25
a=control:track0

客户端请求：
SETUP rtsp://172.29.180.26:8554/live/track0 RTSP/1.0
CSeq: 4
User-Agent: LibVLC/3.0.18 (LIVE555 Streaming Media v2016.11.28)
Transport: RTP/AVP;unicast;client_port=62736-62737

服务端响应：
RTSP/1.0 200 OK
CSeq: 4
Transport: RTP/AVP;unicast;client_port=62736-62737;server_port=39016-39017
Session: 327b23c6

客户端请求：
PLAY rtsp://172.29.180.26:8554/live RTSP/1.0
CSeq: 5
User-Agent: LibVLC/3.0.18 (LIVE555 Streaming Media v2016.11.28)
Session: 327b23c6
Range: npt=0.000-

服务端响应：
RTSP/1.0 200 OK
CSeq: 5
Range: npt=0.000-
Session: 327b23c6; timeout=60