Research Of The Internet Based Video Conference System

With the development of economy and information technology, video conference has a widely used in multimedia communication technology. Traditional video conference systems are mainly based on leased line to setup the special network. In this way, the cost would be high, and the line would be idle when there is no meeting that caused a low utilization rate. To avoid these disadvantages in traditional video conference system, author presented to build video conference system based on H.323 protocol on Internet. In this way, the construction period can be shortened and cost would be down. Also, system utilization rate can be highly improved.The whole project of video conference system was designed in article and two major issues had been solved: Security and QOS. Firstly, Layer-3 VPN IPSec technology was adopted to secure the video conference system, both in encryption and authentication. After analysis of DES,3DES and AES, AES was proved to be reliable than the others in system security. Network throughput had been tested individually with these three algorithms and AES was proved to own the highest encryption rate. This is a great advantage in real-time transfer.Secondly, H.264 technology was adopted to ensure the quality of video transfer.H.264 technology was analyzed from three aspects,PSNR of four kinds of encode/decode tech were tested with software simulation and we can draw the conclusion that H.264 has the higher data compression rate. Furthermore, PSNR performance test with improved H.264 algorithm had been done and the result proved that the improved algorithm has little influence on data compression rate. With real image transfer test, we know that image compressed with H.264 has the best quality in low bandwidth and it was suitable for the system.Finally, according to design scheme, system was constructed in one major meeting place and two branch meeting places. The design scheme of the system was tested and proved that constructing the video conference based on H.323 with Internet is realizable. VPN equipment had influence on system bandwidth and system has to construct the VPN network with hardware encryption. H.264 technology can insure the video conference quality in low bandwidth.