Model-Based Transrating of H.264 Coded Video

This paper presents a model-based transrating (bit-rate reduction) system for H.264 coded video via requantization. In works related to previous standards, optimal requantization step sizes were obtained via Lagrangian optimization that minimizes the distortion subject to a rate constraint. Due to H...

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Vydané v:	IEEE transactions on circuits and systems for video technology Ročník 19; číslo 8; s. 1129 - 1142
Hlavní autori:	Hait, N., Malah, D.
Médium:	Journal Article
Jazyk:	English
Vydavateľské údaje:	New York, NY IEEE 01.08.2009 Institute of Electrical and Electronics Engineers The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Predmet:	Algorithms Applied sciences Bit rate Bit-rate control Circuit properties Coding Computation Computational complexity Computational modeling Constraint optimization Decoding Detection, estimation, filtering, equalization, prediction Electric, optical and optoelectronic circuits Electronic circuits Electronics Exact sciences and technology Frames H264 video coder Image processing Information, signal and communications theory Lagrangian functions Mathematical models Noise levels Optimization PSNR Quantization requantization Sampling, quantization Signal and communications theory Signal convertors Signal processing Signal, noise Size control Standards development Studies Telecommunications and information theory transrating Video coding transrating Information rate H.264 video coder Optimization Video signal processing Signal quantization Traffic control Closed loop Optimal algorithm Coding circuit Estimator Flow rate regulation requantization Teletraffic Quantum effect Decoding circuit Decoding Computational complexity Information transmission Image quality Algorithm performance Bit-rate control Traffic management Comparative study Gain Cascade connection Signal to noise ratio
ISSN:	1051-8215, 1558-2205
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Shrnutí:	This paper presents a model-based transrating (bit-rate reduction) system for H.264 coded video via requantization. In works related to previous standards, optimal requantization step sizes were obtained via Lagrangian optimization that minimizes the distortion subject to a rate constraint. Due to H.264 advanced coding features, the choices of quantization step size and coding modes are dependent and the rate control becomes computationally expensive. Therefore, optimal requantization algorithms developed for previous standards cannot be applied as they are. Hence, previous works on transrating in H.264 focused on changing the input coding decisions rather than on rate control, while requantization was addressed by a simple one-pass algorithm. Here we propose new model-based optimal requantization algorithms for transrating of H.264 coded video. The optimal requantization goal is to achieve the target bit rate with minimal effect on video quality. Incorporation of the proposed models serves two goals. For intra-coded frames, a novel closed-loop statistical estimator that overcomes spatial neighbors dependencies is developed. For inter-coded frames, the proposed macroblock-level models reduce the computational burden of the optimization. Overall, as compared to re-encoding (cascaded decoder-encoder), the proposed system reduces the computational complexity by a factor of about four, at an average PSNR loss of only 0.4 dB for transrating CIF/SIF sequences from 2 Mb/s to 1 Mb/s. In comparison with a simple one-pass requantization, the proposed algorithm achieves better performance (an average PSNR gain of 0.45 dB), at the cost of just twice the complexity.
Bibliografia:	ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 14 ObjectType-Article-2 ObjectType-Feature-1 content type line 23
ISSN:	1051-8215 1558-2205
DOI:	10.1109/TCSVT.2009.2020334