Providing Smoother Quality Layered Video Stream
Srihari Nelakuditi, Raja R. Harinath
Ewa Kusmierek & Zhi-Li Zhang
University of Minnesota, Minneapolis
In recent years, one of the most popular Internet applications
is web-based audio and video playback, where stored video is
streamed from the server to a client on-demand. Rigid playback
deadlines coupled with constraints on resources such as network
bandwidth and client buffer make video delivery a challenging
task . These resources could be limited in such a way that
it may not be possible to deliver full-quality video. In such a
situation, it is desirable to minimize the degradation in the video
quality while operating within the resource constraints . Layered
encoding is proposed to provide finer control on video quality:
the video signal is split into layers and a subset of these
layers is chosen such that the resource constraints are met .
However it is not a trivial task to select layers such that better
but consistent quality playback is ensured when the network
conditions are constantly varying.
In our work, we address this layer selection problem in layered
video delivery and show how smoother 1 quality video play-back
can be provided by utilizing the client buffer for prefetching.
We first define smoothness criteria, design metrics for
measuring it, and then develop off-line algorithms to maximize
smoothness for the case where the network bandwidth is varying
but known a priori. We then describe an adaptive algorithm
for providing smoothed layered video delivery that doesnUt assume
any knowledge about future bandwidth availability. The
results of our experiments for measuring and comparing the performance
these schemes are then presented. We conclude the
paper with a brief discussion on our future work.
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- Last revised: Weds Jun 27 20:56:29 EDT 2000