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Proceedings Paper

Suboptimal quantization control employing approximate distortion-rate relations for motion video coding
Author(s): Yu-Ming Chien; David W. Lin
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Paper Abstract

In typical image and video coding techniques, the choice of quantizer scales at the encoder plays a key role in determining the generated bit-rate and the coding performance. The distortion-rate (D-R) curve of a video unit fully characterizes the relation between quantizing distortion and encoder output rates and can thus be used in the choice of good quanitizer scales. However, obtainment of the D-R curves is a heavy computational load. We develop a piecewise-linear/exponential model to approximate the true curves for macroblocks. Based on this D-R model, we devise a quantizer control method which is a modification of that in Test Model 5 (TM5) for MPEG2. A reference quanitizer scale is first calculated from past bit usages and the buffer fullness as in TM5. Then the slope of each approximated macroblock D-R curve at this quanitizer scale is calculated. In line with human vision characteristics, an adjusted slope value is computed according to a macroblock activity measure. The quantizer scale yielding the adjusted slope on the D-R curve is found and used. Simulation results show that this method of quanitizer choice can attain not only higher PSNR values but also higher visual quality in coded video.

Paper Details

Date Published: 10 January 1997
PDF: 11 pages
Proc. SPIE 3024, Visual Communications and Image Processing '97, (10 January 1997); doi: 10.1117/12.263220
Show Author Affiliations
Yu-Ming Chien, Hewlett-Packard Taiwan Ltd. (Taiwan)
David W. Lin, National Chiao Tung Univ. (Taiwan)


Published in SPIE Proceedings Vol. 3024:
Visual Communications and Image Processing '97
Jan Biemond; Edward J. Delp, Editor(s)

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