An optimal cache algorithm for streaming VBR video over a heterogeneous network

High quality video content for on-demand services is usually stored and streamed in a compressed format with a VBR (variable bit rate) property; however, the streaming traffic is extremely bursty. If there is no client buffer to regulate the video's delivery, the backbone WAN (wide area network) bandwidth needs to allocate the video's peak bit rate to guarantee playback quality. To reduce the bandwidth requirement in the backbone WAN, previous researchers have proposed a Video Staging Mechanism to cache portions of the video in a video proxy close to clients. In this paper, we propose a very effective OC (optimal cache) algorithm to handle the Video Staging Mechanism and prove theoretically that the proxy cache computed by our OC algorithm for each video is minimal when all other resources remain constant. On the basis of experiment results, we cache the least amount of video data in the video proxy by using the OC algorithm, and reduce the WAN bandwidth requirement by an amount equal to that of conventional algorithms. In contrast, given the equal size of the storage in a video proxy, the OC algorithm reduces the bandwidth requirement in the backbone WAN much more than conventional algorithms. © 2005 Elsevier B.V. All rights reserved.