基于代理的分布式视频流点播传输策略

Transmission Scheme for Proxy-Based Distributed Video Streaming on-Demand

视频流传输具有带宽高、周期长的特点 ,使网络带宽成为了制约视频流点播应用发展的主要因素 .本文针对现有网络技术条件 ,充分利用客户端I/O带宽、本地缓存及网络带宽资源 ,设计了一个适用于大规模点播应用的基于代理的分布式视频点播传输策略 .该策略中各本地网络设有一视频流代理服务器用于保存部分视频的部分内容 ,并按动态批处理的方式来接纳并服务请求用户 .视频传输时 ,服务器与代理端之间采用单播传输机制 ,在代理与客户端之间采用单播与多播相结合的方式 .实验表明该策略可以大大减少对骨干网络带宽的需求 ,并能为客户端提供理论上的零启动延时服务 .

Due to the high bandwidth requirements and the long-lived nature of video,network bandwidth is proved to be the major limiting factor in the widespread usage of video streaming on demand over the Internet.Based on the existing network technologies and the capacity of clients and network,such as,I/O bandwidth,local cache,and a transmission scheme for proxy-based distributed video on demand was designed for the context of large-scale video on demand application.In each LAN there lies a proxy,which caches partial content of a part of video assets,admits and serves the request clients in a dynamically batched manner.Unicast alone will be used to transmit the video content on the network paths from the server to the proxy,while multicast or unicast can be chosen to transmit the video from the proxy to the clients.Experimental results have proved that the proposed scheme can greatly reduce the backbone bandwidth usage and provide theoretically null startup latency for clients.