Design And Implementation Of H.323 Protocol-based Video Telephony Terminal

The rapid development of information technology today, experienced a few years ago ordinary telephone swift popularity ,right now the demand for visual telephony gradually gaining。Meanwhile, IPTV become a hot issue with the accelerating of the three networks unite into one network. With the increasing quantity of set-top-box, the value-added services related STB, has started to become a concern of the entire community in one of the hot spots. This research is based on the realization of video phone in the STB,do a depth study for the video conference based on the H.323 protocols. A complete video conferencing system of H.323 includes the terminal, Gateway, Gatekeeper, as well as multi-point control unit. This paper is about the design and realization of a videophone terminal.H.323 as complex framework protocols, we gave a complete and systematic analysis in this paper. We first gave a brief introduction for the physical structure about H.323, and then present the H.323 protocol stack structure. We also gave a Stack a detailed analysis of H.323 stack, which including the structures of H.225.0 RAS, H.225.0 Call Signaling, RCP/RTCP, H.245, and other protocols and the main workflow.Begun to enter the system design and implementation parts after the introduction of the H.323. First were the videophone endpoint architecture design and the overall process of the application procedures, and divided the program modules according to the protocols related with endpoint. Then application of object-oriented programming ideas, introduced the implements of the H.225.0 RAS related classes, H.225.0 call signaling protocol-related classes, RTP protocol related classes, H.245 protocol related classes and the design of the main workflow.In the last chapter, was how to improve the Linux graphics processing capability by the use of DirectFB. This part is the very innovative part in this paper, up to now, have rarely fond similar application reports and articles in domestic. Through the introduction of DirectFB, The Linux graphics processing capability was much improved, particularly in the embedded fields, such as STB, which with videophone functions were very important significance.