基于冷门预判断的P2SP点播系统片选策略的设计与实现

Design and Implemention of Piece Selection in P2SP Network for VoD Based on Cold-prediction Algorithm

结合视频点播应用中对于提高点播质量和减轻服务器负担的要求,设计和实现了一个融合P2P和P2S网络的点播系统xBT。分析现有的BitTorrent协议应用于点播系统的局限性,针对点播过程中存在冷门片段的特点,对BitTorrent协议的片段选择策略提出改进。试验分析表明,xBT在大并发量的点播系统中能够提高用户的播放质量,同时减少服务器压力。

In order to improve the performance of VoD, a hybrid server/P2P streaming system called xBT is introduced for large-scale VoD （Video-on-Demand） service ,which can reduce delay time for play and mitigate the workload of servers. Drawbacks of current BitTorrent protocol for VoD application in a P2P mesh-based network is analyzed and improved the piece selection strategy used in BitTorrent to make it work more efficiently when VCR operations happened. The new piece selection strategy is based on the cold-prediction algorithm. The experiments indicate that xBT can enable the improvement of users＇ experiences in VoD by reducing delay and lower the overhead for servers in large scale VoD system.