A Study of Proxy Cache Mechanism in Video Streaming Applications
Date Issued
2005
Date
2005
Author(s)
Chang, Shin-Hung
DOI
en-US
Abstract
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 dissertation, a one-pass OC (Optimal Cache) algorithm is proposed 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. Additionally, data packets are often lost while streaming video data over the unreliable Internet. These lost packets are often important enough to affect video playback quality and even halt the video playback. Therefore, we refine the OC algorithm and propose a novel PSC (Priority Selected Cache) algorithm to select maximum high-priority video data for caching in a video proxy. The PSC algorithm inherits to use minimum storage in video proxy and reduces the maximum bandwidth requirement of video server (as does the OC algorithm). Additionally, the PSC algorithm also prevents the decoding errors caused by packet loss, improve error recovery, and provide QoS-guaranteed video playback. 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. Furthermore, we show that the PSC algorithm caches more high priority video data in a video proxy server than the original OC algorithm.
Subjects
異質性網路
視訊暫存
階段式視訊儲存
視訊串流
變動位元速率視訊
Heterogeneous Network
Video Cache
Video Staging
Video Streaming
VBR Video
Type
thesis