Segment-Based Proxy Caching of Multimedia Streams

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 object, 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
management 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 values 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
without 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 advantageous 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.