Application Research Of Video Streaming On-Demand Over IP Network

Since its introduction in early 1990s, the concept of streaming media has experienced a dramatic growth and transformation from a novel technology into one of the mainstream manners in which people experience the Internet today. Its application has been extended through almost all aspects of Internet service such as entertainment, Internet Broadcast, distance education, videoconference etc. However, due to the high bandwidth requirements and the long-lived nature of video, server and network bandwidths are proved to be major limiting factors in the widespread usage of video streaming over the Internet. This is further complicated by the fact that the client population is likely to be large, with different clients asynchronously issuing requests to receive their chosen media streams. Thus video streaming on-demand, which is the most popular and most important distribution mode of streaming media, even today is still severely limited in scope and reach.In order to improve the QoS (quality of service) of the VOD system, this dissertation introduces several principles to design the video streaming on-demand system, then presents three kinds of system structures according to the scale of the VOD system, and then designs several corresponding schemes or policies to optimize the performance of the VOD system.In chapter 3, we design a multicast scheme named Dynamic Batched Patching, which can be considered as an ameliorative Patching algorithm. This scheme can be implemented simply, and it can decrease the start-up latency for the clients. An outstanding advantage of this multicast scheme is system resource utilization, and as a result the access capacity of the system can be increased obviously.The scheme presented in chapter 3 cannot directly provide support for VCR-like functionality which is important for VOD system, thus we propose a least-cost model for the efficient implementation of MPEG streaming video system to provide full VCR functionality over a network with minimum requirements on the network bandwidth and the decoder complexity.In order to increase further the access capacity of the VOD system and decrease the start-up latency for the clients, this dissertation designs a new caching policy for VOD server in chapter 5. This caching policy makes good use of the characteristic of the Dynamic Batched Patching algorithm; the results of simulation have proved thatthis caching policy can obtain a high Byte Hit Ratio, that is, this caching policy can decrease the requirement of video server I/O bandwidth even in the context of efficient multicast system.Although multicast significantly reduces network bandwidth, it is often considered impractical in large-scale VOD application system due to its reliance on a fully multicast-enabled network, which is not widely available over the Internet, and even today remains severely limited in scope and reach. In order to increase the access capacity of the system, decrease the requirement of system recourses, and provide theoretical null startup latency for clients, a proxy-based distributed video on-demand scheme is proposed in the chapter 6, which consists of two policies: transmission policy and proxy caching policy. The results of simulation experiment prove that the proposed policy is very efficient.Finally, conclusions and prospects are given in chapter 7.