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Proceedings Paper

Toward optimal rate control: a study of the impact of spatial resolution, frame rate, and quantization on subjective video quality and bit rate
Author(s): Demin Wang; Filippo Speranza; Andre Vincent; Taali Martin; Phil Blanchfield
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Paper Abstract

Multi-dimensional rate control schemes, which jointly adjust two or three coding parameters, have been recently proposed to achieve a target bit rate while maximizing some objective measures of video quality. The objective measures used in these schemes are the peak signal-to-noise ratio (PSNR) or the sum of absolute errors (SAE) of the decoded video. These objective measures of quality may differ substantially from subjective quality, especially when changes of spatial resolution and frame rate are involved. The proposed schemes are, therefore, not optimal in terms of human visual perception. We have investigated the impact on subjective video quality of the three coding parameters: spatial resolution, frame rate, and quantization parameter (QP). To this end, we have conducted two experiments using the H.263+ codec and five video sequences. In Experiment 1, we evaluated the impact of jointly adjusting QP and frame rate on subjective quality and bit rate. In Experiment 2, we evaluated the impact of jointly adjusting QP and spatial resolution. From these experiments, we suggest several general rules and guidelines that can be useful in the design of an optimal multi-dimensional rate control scheme. The experiments also show that PSNR and SAE do not adequately reflect perceived video quality when changes in spatial resolution and frame rate are involved, and are therefore not adequate for assessing quality in a multi-dimensional rate control scheme. This paper describes the method and results of the investigation.

Paper Details

Date Published: 23 June 2003
PDF: 12 pages
Proc. SPIE 5150, Visual Communications and Image Processing 2003, (23 June 2003); doi: 10.1117/12.501266
Show Author Affiliations
Demin Wang, Communications Research Ctr. Canada (Canada)
Filippo Speranza, Communications Research Ctr. Canada (Canada)
Andre Vincent, Communications Research Ctr. Canada (Canada)
Taali Martin, Communications Research Ctr. Canada (Canada)
Phil Blanchfield, Communications Research Ctr. Canada (Canada)

Published in SPIE Proceedings Vol. 5150:
Visual Communications and Image Processing 2003
Touradj Ebrahimi; Thomas Sikora, Editor(s)

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