Abstract
The H.264/AVC video standard adopts a fixed search range (SR) and fixed reference frame (RF) for motion estimation. These fixed settings result in a heavy computational load in the video encoder. We propose a dynamic SR and multiframe selection algorithm to improve the computational efficiency of motion estimation. By exploiting the relationship between the predicted motion vector and the SR size, we develop an adaptive SR adjustment algorithm. We also design a RF selection scheme based on the correlation between the different block sizes of the macroblock. Experimental results show that our algorithm can significantly reduce the computational complexity of motion estimation compared with the JM15.1 reference software, with a negligible decrease in peak signal-to-noise ratio and a slight increase in bit rate. Our algorithm also outperforms existing methods in terms of its low complexity and high coding quality.
Highlights
Motion estimation (ME) is used in many video coding standards, such as MPEG-1, MPEG-4, and H.264/AVC, to remove interframe redundancies
The simulations were performed with rate distortion (RD) optimization and Hadamard transform enabled, quantization parameters (QPs) 1⁄4 28, 32, 36, and 40, IPPP sequence types, CAVLC entropy coding, and one or five reference frame (RF)
CPX (%)[4] is the speed-up ratio of the search range (SR) adjustment algorithm, which is defined as the ratio of the number of search points in the proposed method to the number of search points in the full-search motion estimation (FME) algorithm
Summary
Motion estimation (ME) is used in many video coding standards, such as MPEG-1, MPEG-4, and H.264/AVC, to remove interframe redundancies. The priorities of all RFs can be computed from the spatial and temporal correlation of the RF index and MVs,[18] or the coding modes and RFs from some reference region may be used to determine the CRFs for the current block.[19] In Ref. 20, the initial RF is dynamically selected using the mean of the RF indexes of spatially neighboring MBs. The third category speeds up the multiframe selection procedure by employing an early termination strategy. For the multiframe selection scheme, we focus on the correlation between different block sizes of the MB to adaptively select RFs. Simulation results show that the proposed algorithm achieves a higher speedup while maintaining almost the same video quality and total bit rate. Jmvdnj represents the magnitude of the difference between MV and PMV, and
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