The Research And Implement Of Video Conference Terminal System Based On H.323 Protocol

Recent years have seen growing interesting in video conference system based on H.323 standard. A complete video conference system of H.323 includes Terminal, Gateway, Gatekeeper and Multi-Control Unit (MCU). This paper focus on the design and implement a Terminal of video conference system, include the extension of multimedia control protocol (H.245), video component, and the Terminal software. First, as a complex set of protocols, we gave a complete and systemic analyze on H.323, include its main three parts: H.225, H.245 and RAS protocol. Different from other implement of H.323 protocol stack, our work based on an exited H.323 stack which implement with language C. We extend this stack in two sides: extend the implement of H.245 protocol (extend the capability set change mode, set up and manage the logical channel of video), and design and implement the video component (the video transfer module based on RTP protocol, video capture and replay on Windows platform, integrate a video codec H.261). Because the jitter of Internet will seriously impact the transfer of multimedia data, we propose and implement an auto-adapt Jitter Buffer algorithm in the system. At last, we develop a basic terminal software based on our stack. We also set up a test platform to test the function and performance of our stack and Terminal software include the interactive with other video conference system which is also based on H.323 standard, and this platform can gave us more benefit for the future research and development.