Authors: Reza Rejaie, Mark Handley, Haobo Yu, Deborah Estrin.
Despite the success of proxy caching in the Web, proxy servers have not been used effectively for caching of Internet multimedia streams such as audio and video. Explosive growth in demand for web-based streaming applications justifies the need for caching popular streams at a proxy server close to the interested clients.
Because of the need for congestion control in the Internet, multimedia streams should be quality adaptive. This implies that on a cache-hit, a proxy must replay a variable-quality cached stream whose quality is determined by the bandwidth of the first session.
adaptation on proxy caching mechanisms for streaming applications. We present a fine-grain replacement algorithm for layered-encoded multimedia streams at Internet proxy servers, and describe a pre-fetching scheme to smooth out the variations in quality of a cached stream during subsequent playbacks. This enables the proxy to perform quality adaptation more effectively and maximizes the delivered quality. We also extend the semantics of popularity and introduce the idea of weighted hit to capture both the level of interest and the usefulness of a layer for a cached stream. Finally, we show that interaction between our replacement algorithm and pre-fetching results in the state of the cache converging to the optimal state such that the quality of a cached stream is proportional to its popularity, and the variations in quality of a cached stream are inversely proportional to its popularity. This implies that after serving several requests for a stream, the proxy can effectively hide low bandwidth paths to the original server from interested clients.
Keywords: Proxy Caching Mechanism, Congestion Control, Quality Adaptive Video Playback, Layered Transmission, Internet
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