KEYWORDS: Feature extraction, Distance measurement, Binary data, Detection and tracking algorithms, Image processing, Databases, Signal to noise ratio, Information security, Biometrics, Digital watermarking
This paper discusses one of the important issues in generating a robust media hash. Robustness of a media
hashing algorithm is primarily determined by three factors, (1) robustness-false alarm tradeoff achieved by the
chosen feature representation, (2) accuracy of the bit extraction step and (3) the distance measure used to measure
similarity (dissimilarity) between two hashes. The robustness-false alarm tradeoff in feature space is measured
by a similarity (dissimilarity) measure and it defines a limit on the performance of the hashing algorithm. The
distance measure used to compute the distance between the hashes determines how far this tradeoff in the
feature space is preserved through the bit extraction step. Hence the bit extraction step is crucial, in defining
the robustness of a hashing algorithm. Although this is recognized as an important requirement by all, to our
knowledge there is no work in the existing literature that elucidates the effcacy of their algorithm based on their
effectiveness in improving this tradeoff compared to other methods. This paper specifically demonstrates the
kind of robustness false alarm tradeoff achieved by existing methods and proposes a method for hashing that
clearly improves this tradeoff.
KEYWORDS: Video, Internet, Video processing, Local area networks, Sun, Visual communications, Image processing, Electronic imaging, Data communications, Multimedia
There are great challenges in streaming variable-bit-rate video over wide-area networks due to the significant variation
of network conditions. The utilization of the precious bandwidth of wide-area networks is often low in such streaming
systems. In this paper, we propose a novel framework to improve the bandwidth utilization from a new perspective.
Instead of focusing on the performance of each single media stream, we aim to improve the overall bandwidth utilization
for video streaming systems. We try to exploit the unoccupied bandwidth in ongoing streams and using it to deliver
some prefetched data which can be used to facilitate future streaming. Preliminary results show that our mechanism has
great potential to improve both the overall bandwidth utilization and the caching performance of the proxy servers in the
streaming systems.
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