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Proceedings Paper

Adaptive block transforms for hybrid video coding
Author(s): Mathias Wien; Claudia Mayer
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Paper Abstract

Today's standard video coders employ the hybrid coding scheme on a macroblock basis. In these coders blocks of 16 X 16, and 8 X 8 pixel are used for motion compensation of non- interlaced video. The Discrete Cosine Transform (DCT) is then applied to the prediction error on blocks of size 8 X 8. The emerging coding standard H.26L employs a set of seven different block sizes for motion compensation. The size of these blocks varies from 4 X 4 to 16 X 16. The block sizes smaller than 8 X 8 imply that the 8 X 8 DCT cannot be used for transform coding of the prediction error. In the current test model an integer approximation of the 4 X 4 DCT matrix is employed. In this paper the concept of Adaptive Block Transforms is proposed. In this scheme, the transform block size is adapted to the block sizes used for motion compensation. The transform exploits the maximum possible signal length for transform coding without exceeding the compensated block boundaries. The proposed scheme is integrated into the H.26L test model. New integer approximations of the 8 X 8 and 16 X 16 DCT matrices are introduced. Like the TML 4 X 4 transform the coefficient values of these matrices are restricted to a limited range. The results presented here are based on an entropy estimation. They reveal an increased rate/distortion performance of approximately 1.1 dB for high rates on the employed test sequences.

Paper Details

Date Published: 29 December 2000
PDF: 10 pages
Proc. SPIE 4310, Visual Communications and Image Processing 2001, (29 December 2000); doi: 10.1117/12.411793
Show Author Affiliations
Mathias Wien, Rheinisch-Westfaelische Technische Hochschule Aachen (Germany)
Claudia Mayer, Rheinisch-Westfaelische Technische Hochschule Aachen (Germany)

Published in SPIE Proceedings Vol. 4310:
Visual Communications and Image Processing 2001
Bernd Girod; Charles A. Bouman; Eckehard G. Steinbach, Editor(s)

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