Terminating CU splitting in HEVC intra prediction using the Hadamard Absolute Difference (HAD) cost

Abstract

High Efficiency Video Coding (HEVC), the current video coding standard provides improved compression performance compared to its predecessor, AVC/H.264. It adopts a highly flexible quad-tree coding block partitioning which results in significant compression gain. However, in order to select the best Coding Unit (CU) size, every coding unit of all sizes needs to be traversed. This imposes a heavy computational burden on the encoder. In this paper, a fast early coding unit selection is therefore proposed based on the Hadamard Absolute Difference (HAD) cost. For each CU size, the splitting process is terminated if the HAD cost is below a specified threshold. In addition, for the 8 × 8 CUs, only Prediction Units (PUs) of size 2N × 2N are allowed based on the difference between the HAD cost of the best mode and the DC coefficient. Experimental results show that the proposed method provides a decrease of 41.2% computation time on average, compared to HEVC reference software, with an increase of only 0.003% in bit-rate.