对扩展视频点播系统服务能力进行了研究。在所提出的ContribVoD 系统中, 通过用户相互共享各自拥有的视频数据,使服务器不再是视频数据的唯一来源,从而可分散视频服务器的负担,提高系统的服务能力。系统通过优化查询、数据传输动态监控及初始缓冲来保证用户的播放质量,同时利用种子选择策略来尽量避免远程数据传输,减小主干网络的负担。仿真实验显示,系统的服务能力比基于C/S 模式的视频点播系统有显著提高。 关键词:对等,视频点播,流媒体,播放质量 Abstract:ContribVoD is a p2p approach to extend the ability of Video on Demand systems to serve more users. In the proposed system users share with each other the media data obtained and the media server is no longer the only source to get data from, thereby, the load on the media server could be greatly alleviated and the overall system capacity increases and more users could be served. ContribVoD introduces efficient searching, data transfer dynamically monitoring and initial buffering to maintain a high quality of playback. Its provider selection policy helps to reduce the load of the underlying network by avoiding remote data transfer. Simulation results show that ContribVoD could greatly outperform the traditional C/S based VoD systems with respect to the amount of users could be served. Key words: p2p,peer to peer, video on demand ,streaming media,QoS