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25 October 1995 Comparison of the H.263 and H.261 video compression standards
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The draft international standard ITU-T H.263 is closely related to the well known and widely used ITU-T Recommendation H.261. However, H.263 does provide the same subjective image quality at less than half the bit-rate. In this paper we investigate to what extend single enhancements of H.263 contribute to this performance gain, and consider the trade-off quality vs. complexity. Based on the test sequence “Foreman”, H.263 in its default- and optional codingmodes is compared to H.261 on the basis of rate distortion curves at bit-rates up to 128 kbps. At 64 kbps, the performance gain of H.263 in its default mode compared to H.261 is approximately 2 dB PSNR. This improvement is achieved with only little increase of complexity, and is mainly due to more accurate motion compensation with half-pel accuracy. Considering the trade-off quality vs. complexity, the combination of the optional coding-modes “Advanced prediction mode” and “PB-frames mode” seems to be a good compromise, resulting in an additional performance gain of 1 dB PSNR at 64 kbps. The “Syntax-based arithmetic coding mode” on the other hand, offers only a very small performance gain (0.2 dB PSNR at 64 kbps) for its increased computational complexity. Results from profiling a H.263 software codec are presented in order to support complexity considerations of the optional coding-modes.
© (1995) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Bernd Girod, Eckehard G. Steinbach, and Niko Faerber "Comparison of the H.263 and H.261 video compression standards", Proc. SPIE 10282, Standards and Common Interfaces for Video Information Systems: A Critical Review, 102820D (25 October 1995);


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