Research And Implementation On The Multipoint Multimedia Conference System Based On SIP

With the development of multimedia technology and communication technology by network, the business of multimedia communication, especially the VoIP (Voice over IP) technology, has become a leading element in Internet applications. It refers to not only the IP Phone, but also a comprehensive application platform that provides various multimedia operations including video exchange. Nowadays, the requirements for multimedia conference are not only the audio and video with high quality, but also the functions of file transmission and application shared between conferencing participates.Most of VoIP systems are based on two kinds of call control protocol: SIP and H.323. Because of the complexity and inflexibility of the multipoint conference based on H.323, it is gradually replaced by the one based on SIP, which is simple and agile. Therefore, deeply researches on the construction of SIP based network on Windows platform are carried out, and we emphasize on the collaboration between multimedia conference and data conference.This paper aims to have a deeply study into several key techniques about SIP and multimedia conference system. Firstly, some relevant protocols and methods of the multimedia conference system are studied, and a user agent system is designed and implemented based on protocol stack. It realizes the transmission and live display in synchronism of the video and the audio. Furthermore, some opinions about the multi-services SIP server are presented. Secondly, the multimedia data conference protocols are studied. By summarizing two schemes on implementing cooperation between data conference and the multimedia conference, which are T.120 and duel stream, we propose the IDC (Insert Data Conference) method. Comparison of the three methods reveals the characteristic of agile and less consumption. Finally, e-whitebroad based on a UA (User Agent) and file transmission function are accomplished with IDC method to realize the collaboration with multimedia conference and data conference. Analysis of system function modules and test results illustrate the feasibility and effectiveness of the designed user agent system.