The Implementation Of An IP Video Terminal Based On SIP Protocol

With the development of technology in the network and multimedia area, the business of multimedia communication, especially the VOIP technology, has become a leading element in Internet applications. VOIP is the abbreviation of Voice communication Over IP net. It refers to not merely the IP Phone, but also a comprehensive application platform that provides various multimedia operations including video exchange.Most VOIP systems are based on SIP or H.323 call control protocols. The Session Initiation Protocol(SIP) advanced by IETF has its distinct advantages: it is very concise 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 a multi-domain network effectively. Under the circumstance that Softswitch is to become the next generation technology of network switch, SIP is considered as the kernel protocol in access layer of the Soft switch technology, and it has been successfully applied to several representative communication systems due to the interest of lots of famous telecommunication companies.From this point, we have carried out some research work in the construction of SIP based network on Windows platform. This network includes the SIP terminal and server. And our research work includes SIP stack, video and audio codecs and network transmission. This paper also provides some background knowledge about SIP and Video Conference, such as the SIP framework, the history of VOIP and Video Conference, etc.This paper emphasizes on the implementation of SIP terminal on the Windows platform, including the realization of SIP stack, the capture and compression of video and audio steams, RTP transmission of stream data, the working thread of SIP terminal and the optimization of video codecs. This paper also introduces the structure of standard Video Conference, demonstrates the importance of SIP in the Softswitch network and makes comparison between SIP and the H.323 standard. In the first chapter the history and framework of Video Conference is introduced, and then the author's research work is also introduced. In the second chapter the author firstly introduces the structure and network model of SIP, then compares SIP with the H.323 standard, and demonstrates the importance of SIP according to the Softswitch network. In the third chapter, the author discusses the realization of SIP terminal in detail,including the implementation of all modules. The author brings out some opinions about the multi-services SIP server in the forth chapter, including its theory and structure. The fifth chapter is about some conclusions and tasks in the future.