Summary: To appear in Proc. Multimedia Computing and Networking 2000, San Jose, CA, January 2000. 1
Bandwidth Skimming: A Technique for
Derek Eager Mary Vernon John Zahorjan
Dept. of Computer Science Computer Sciences Dept. Dept. of Comp. Sci. & Eng.
Univ. of Saskatchewan Univ. of Wisconsin Univ. of Washington
Saskatoon, SK S7N 5A9 Canada Madison, WI 53706 Seattle, WA 98195-2350
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Video-on-demand applications must consider the bandwidth limitations at the server, within the network, and at the client.
Recent multicast delivery techniques have addressed the server and network bandwidth bottlenecks. These techniques,
however, neglect consideration of client network access bandwidth limitations. Client bandwidth is often insufficient to
permit streaming video of the quality that clients would desire, yet these new multicast delivery techniques require clients to
be capable of receiving two or more transmission streams simultaneously, each at the playback bit rate. The reduction in the
playback bit rate required to use these techniques implies substantially poorer display quality.
This paper proposes a new technique for on-demand delivery of streaming media that addresses this problem. The idea is
to hold in reserve, or "skim", a portion of the client reception bandwidth that is sufficiently small that display quality is not
impacted significantly, and yet that is nonetheless enough to support substantial reductions in server and network bandwidth
through near-optimal hierarchical client stream merging. In this paper we show that this objective is feasible, and we develop
practical techniques that achieve it. The results indicate that server and network bandwidth can be reduced to on the order of