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Proceedings Paper

Forward-adaptive quantization with optimal overhead cost for image and video coding with applications to MPEG video coders
Author(s): Antonio Ortega; Kannan Ramchandran
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Paper Abstract

We address the problem of optimal forward-adaptive quantization in the video and image coding framework. In this framework, as is consistent with that of most practical coders like MPEG, the encoder has the capability of changing the quantizer periodically (e.g. at a macroblock interval in MPEG). In this paper, we formulate an optimal strategy, based on dynamic programming, for updating the quantizer choice for coding an image or video signal. While in some coding environments the overhead needed to specify the quantizer used by each block is equal for every choice of quantizer, in other situations (e.g. MPEG) the overhead cost is higher if the quantizer changes from one block to the next. We concentrate on the latter case which will be more likely encountered in situations where the overhead represents a significant fraction of the overall rate, as can be the case if a low bit rate is used (e.g. error frames in a typical motion-compensated video coder). We provide empirical evidence of the performance gain that can be obtained when applying our optimal algorithm to typical motion-compensated prediction error frames in MPEG, showing how the popular Viterbi algorithm can be used to find the optimal solution.

Paper Details

Date Published: 17 April 1995
PDF: 10 pages
Proc. SPIE 2419, Digital Video Compression: Algorithms and Technologies 1995, (17 April 1995); doi: 10.1117/12.206352
Show Author Affiliations
Antonio Ortega, Univ. of Southern California (United States)
Kannan Ramchandran, Univ. of Illinois/Urbana-Champaign (United States)

Published in SPIE Proceedings Vol. 2419:
Digital Video Compression: Algorithms and Technologies 1995
Arturo A. Rodriguez; Robert J. Safranek; Edward J. Delp, Editor(s)

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