Segment-based proxy caching of multimedia streams

Abstract

As streaming video and audio over the Internet becomes popular, proper proxy caching of large multimedia objects has become increasingly important. For a large media ob-ject, such as a 2-hour video, treating the whole video as a single web object for caching is not appropriate. In this paper, we present and evaluate a segment-based buffer man- A gement approach to proxy caching of large media streams. Blocks of a media stream received by a proxy server are grouped into variable-sized segments. The cache admission and replacement policies then attach different caching val-ues to different segments, taking into account the segment distance from the start of the media. These caching policies give preferential treatments to the beginning segments. As such, users can quickly play back the media objects with-out much delay. Event-driven simulations are conducted to evaluate this segment-based proxy caching approach. The results show that (1) segment-based caching is effective not only in increasing byte-hit ratio (or reducing total traffic) but also in lowering the number of requests that require delayed starts; (2) segment-based caching is especially ad-vantageous when the cache size is limited, when the set of hot media objects changes over time, when the media file size is large, and when many users may stop playing the media after only a few initial blocks.