Research And Realization Of VOD System Based On IP

With the development of high-speed computer network , digital compression and storage technology,real-time Multimedia communication service based IP grows rapidly. Video-on-Demand is one of the most appealing application of multimedia, it applies extensivly to the amusement , education , communication and computer industry, and is accepted by the masses of users finally, become amusement and the most important form of obtaining information service while doing in their life and work. At present, Stream-media technology already relatively riper based on IP, it enables user watch TV immediately by the "watch TV while downloading video datda "way; Correlate with what the content distributed technology (content deliver network , IP multicast and peer-to-peer ) offer the large scale Video-on-Demand(VOD) possible. And a lot of questions related to VOD concentrate on the question of delivering of content of the video server, so the research contents of this paper mainly concentrate on the server's service policy, consider how utilize IP-Multicast technology to realize stream-sharing mechanism, and propose a solution of interactive VOD based on stream-sharing. This paper proposes a VoD solution called UVoD that unifies the existing TVoD and NVoD architectures by integrating unicast with multicast transmissions.By unicast transmission, Then server's channel is consisted of unicast channel nad multicast channel,and they are scheduled together. By unicast transmission,the system t reserve dedicated video channel for each user ,that can enable user watch any movie at any time. And multicast with batching and patching policy can enable several users share a same video stream, so the server can provide service for more users by limited resource. But,in multicast channel, the movie must be satisfied with popularity model, and the system must ensure small service delay,so this solution can flexibly use unicast channel to provide service when avove conditions is not satisfied; and because the users's operations are not independent,so the server reserve some unicast channel to provide interactive function for users,and make use of the "split and merge"technology to enable that data transmission can migrate between unicast channel and multicast channel. This solution take the tradeoff between service delay and channel number into account,and is a practicable solution.