Design And Implementation Of SIP-based Video Conferencing Systems

With the development of technology in the network and multimedia area, thebusiness of multimedia communication, especially the VoIP technology, hasbecome a leading element in Internet applications. VoIP is the abbreviation of Voicecommunication Over IP net. It refers to not merely the IP Phone, but also acomprehensive application platform that provides various multimedia operationsincluding video exchange. Most VoIP systems are based on SIP or H.323 call control protocols. The SessionInitiation Protocol(SIP) advanced by IETF has its distinct advantages: it is veryconcise in the structure, easy to be extended and more suitable to access the Internet.It can control the media gate way and thus control the PC call streaming in amulti-domain network effectively. Under the circumstance that Softswitch is tobecome the next generation technology of network switch, SIP is considered as thekernel protocol in access layer of the Soft switch technology, and it has beensuccessfully applied to several representative communication systems due to theinterest of lots of famous telecommunication companies. From this point, I have carried out some research work in the construction ofSIP based network on Windows platform. This network includes the SIP terminal andserver. And our research work includes SIP stack, video and audio codecs andnetwork transmission.This paper emphasizes on the implementation of SIP terminal on the Windowsplatform, including the realization of SIP stack, the capture and compression ofvideo and audio steams, RTP transmission of stream data, the working thread of SIPterminal and the optimization of video codecs. This paper also makes comparisonbetween SIP and the H.323 standard.