A fast inter-prediction algorithm for HEVC based on temporal and spatial correlation

Abstract

In HEVC, the structure of coding unit (CU) and prediction unit (PU) is defined, which brings about higher coding efficiency than H.264/AVC. However, the rate distortion (RD) cost calculations of all depths of CUs and partition modes have yielded tremendous coding computational complexity. In order to reduce the complexity, a fast inter-prediction algorithm is proposed based on temporal and spatial correlations in this paper. In the proposed algorithm, the optimal partition mode in HEVC is selected based on its occurrence probability among all the partition modes and the similarity of the CU segmentation and partition mode between two adjacent frames is counted. Based on the optimal mode and similarity of CU segmentation and partition mode, at most two partition modes are evaluated for each CU to save computational complexity. In addition, the spatial correlation of CU segmentation and partition mode between the corresponding located (co-located) CU and its four surrounding CUs are analyzed. Based on this spatial correlation, only the optimal partition mode is evaluated to save the computational complexity for the deeper depths of CUs of the current CU. Simulation results show that the proposed algorithm achieves 65 % coding time reduction with negligible loss in coding efficiency and peak signal-to-noise ratio (PSNR), compared to previous fast mode decision algorithm.