With the development of computer networks and multimedia communications, video conferencing is applied more widely, and it has good prospects for the development and research value. H.323 and SIP is currently the two major video conferencing standard based on IP network, taking into account the interoperability and compatibility with the original standard H.320, this paper chose the H.323 protocol based on IP network as a framework for the video conference system architecture.Based on the analysis and research of H.323, this paper provided the architecture of the video conference system, and analysed the key module. It presented the superiority of TMS320DM6446 which is a video conferencing terminal.It researched and implemented the far end camera control and MPEG-4 video transport in video conferencing.Video conferencing based on IP network transmits real-time images, audio and other data. If adding far end camera control in the video conference system, the various movements of the far end camera would be controlled arbitrarily, it will greatly improve the effectiveness of remote monitoring. So researching the far end camera Control is very important. Through research and comparative analysis of the various far end camera control protocol, this paper adopted the H.224/H.281 as far end camera control protocol of video conference system. Through analysis of H.224/H.281, it researched the methods of H.224/H.281 far end camera control in the video conference system, gived the existing problems when adding H.224/H.281 in the H.323 system and gived the solution, provided the design and realization of H.224/H.281 far end camera control, and verified that the H.224/H.281 far end camera control is correct through testing.Video conferencing adopted H.323 uses the video compression standards H.261 and H.263, the two standards exist low-coding efficiency, low efficiency of transmission, low quality of reconstruction image, and so on. MPEG-4 is the international video codec standard which has the superior performance, improves low bit-rate compression and increases fault-tolerant, and has better performance than ever standards (H.261 and H.263).So it is significant to research the transport of MPEG-4 video in video conferencing.Through the research of MPEG-4 video standard and MPEG-4 key technologies, including the DCT, quantization, motion estimation and motion compensation and VLC coding technology, this paper researched MPEG-4 video transport method in the video conference system, gived the existing problems when adding MPEG-4 video transport in the H.323 system and gived the solution, designed and implemented the transport of MPEG-4 video, provided the MPEG-4 video transmission model. And through the experiment on the two standard video sequences, it compared and analysed the results of the MPEG-4 video transmission and H.263 video transmission, the results had been satisfactory.
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