P2P视频点播中的VCR方法综述

A Survey of the VCR Methods in P2P Video on Demand

近几年,P2P视频点播技术得到了广泛的发展,使用P2P流媒体播放器(如PPStream、PPLive)来点播视频已经被广泛接受。但是,由于种种原因,用户在播放视频时进行快进、快退和跳转操作时,总是要等待一个比较长的时间,与用户在本地执行此操作的时间相差较大,因此用户得不到好的点播体验,同时也浪费带宽。为了解决这个问题,研究者们已经提出了许多关于提高VCR质量的方法,其中有被动式技术,也有主动式技术。被动的VCR技术主要是着眼于缩短对资源节点定位时间和从该资源节点下载资源的时间,同时提高节点保存资源节点信息的概率。主动的VCR技术主要是提高预存内容的概率和预存资源节点的信息的概率,同时缩短对资源节点定位的时间。本文将着重介绍这些方法的特征,并比较他们的优缺点,最后对VCR算法研究做出展望。

In recent years,the technology of P2P VOD has got a comprehensive development.It is widely accepted that people use a streaming media player based on P2P to play videos on Internet.But for many reasons,the users have to wait for a long time when they perform fast forward,fast rewind,and jump operations in playing videos,which is quite different from performing those operations on videos in local computers.Consequently,the users are not satisfied with it.In order to solve this problem,researchers propose many VCR solutions,which include the passive technologies and the active technologies.The passive technologies focus on reducing the time of locating the source node and downloading sources from it,at the same time,improve the possibility of saving the information of the source node.Active technologies focus on improving the possibility of the pre-saved content of video and the information of the source node.This paper plays emphasis on introducing the characteristics of these algorithms and comparing their merits and limitations.At the end,a view of the future development of VCR will be given in order to provide a reference to future study.