Research On Key Technology Of Digital Video Service

It has become feasible to provide digital video service with improved performance of computers, enlarged bandwidth of networks, and progress in compressing technology of video data. In this dissertation, the relevant key technology is studied, and a prototype system is implemented. The results are as follows:1 An approach to establish real-time video server system with normal PC servers and unreal-time operation system is provided. The normal server is expanded in software and hardware to make output video streams satisfying DVB-C standard, and to provide video service by cable TV. The real-time soft multiplex of MPEG-2 transport stream and the flow control policies of real-time video data output are also implemented.2 The approaches to guarantee quality of service of video server are provided, including flow control, error control, and admission control policies of video server.3 The bandwidth control approach of the storage system is provided to deal with the competition between the internal data scheduling and the real-time data output in order to satisfy the deadline limitation of the data output. Furthermore, the load scheduling policy and cache disk scheduling policy are compared and the passive cache-hit priority approach is provided as the scheduling policy of the video server.4 A mechanism of high availability of video server is proposed. The mechanism is based on more to more resource backup. One resource has r backup resources and any reserve resource could backup for more other r esources. The load o f the failed nodes could be taken o ver by reserve resource and no overload arise in the system with the condition of no more than r failed nodes. The backup relationship is represented by r backup graph (bipartite graph), resource graph and failure graph. By making the complete matching r backup graph for the failure graph, the sufficient conditions of resource distribution are proposed and proved respectively with arbitrary distribution and regular distribution of reserve resource. The load distributing and scheduling algorithm to implement the mechanism in the cluster system is given.