Search

The new video coding standard, H.264/MPEG-4 AVC, uses variable block sizes ranging from 4 x 4 to 16 x 16 in interframe coding. This new feature has achieved significant coding gain compared to coding a macroblock (MB) using fixed block size. However, this feature results in extremely high computational complexity when brute force rate distortion optimization (RDO) algorithm is used. This paper proposes a fast intermode decision algorithm to decide the best mode in intercoding. It makes use of the spatial homogeneity and the temporal stationarity characteristics of video objects. Specifically, spatial homogeneity of a MB is decided based on the MB's edge intensity, and temporal stationarity is decided by the difference of the current MB and it colocated counterpart in the reference frame. Based on the homogeneity and stationarity of the video objects, only a small number of intermodes are selected in the RDO process. The experimental results show that the fast intermode decision algorithm is able to reduce on the average 30% encoding time, with a negligible peak signal-to-noise ratio loss of 0.03 dB or, equivalently, a bit rate increment of 0.6%. Index Terms--Video coding, H.264, AVC, RDO, homogeneity, stationarity, inter mode.

Inner product evaluation can be considered to be basic to all digital signal processing algorithms. Distributed arithmetic {DA) is a bit serial memory-oriented method that implements inner products. In DA, memory increases exponentially as the number of coefficients increases. This deters the use of DA in the implementation of DSP algorithms. This paper explores the possibility of combining DA principles with the residue number system (RNS) to exploit the advantages of both. A new technique for the computation of the inner product in the RNS domain using modular multipliers and DA principles is proposed. The resulting architecture is elegant, uses minimum memory and adders, and hence is VLSI efficient. The proposed architecture is extremely efficient in terms of speed and does not involve conversion of data into residues although computation is performed in residue domain. Index Terms - Distributed arithmetic, modular multiplier, residue number system.

A novel Markov random field model for estimating dense motion and uncovered background fields in images, is presented.