sip，sdp，sap之间的关系。以及应用。非常好的理解sip的一篇文摘-sip, sdp, the relationship between sap. , And applications. Sip a very good understanding of a CAS

这是RTSP和SDP协议，在网上找的都是TXT的版本，我把它做成了PDF，这样就更好阅读。-This is RTSP and SDP, in looking at the online version are TXT, I see it turned into a PDF, so better reading.