A Fast Inter Mode Decision Algorithm for HEVC Encode System based on Spatial and Temporal Correlations

Abstract

With the development of video display technology, high efficiency video coding (HEVC) has recently been proposed to optimize the coding efficiency of video encoders, and it has demonstrated great improvements in coding efficiency by using the layered structure of the coding unit (CU), transform unit (TU), and prediction unit (PU). For the purpose of accomplishing the prefect coding efficiency, we must find the best combination of CU, TU, and PU in the situation of the lowest rate distortion (RD) cost, which is time-consuming. Among these CU, TU, and PU, the determination of CU size has the most significant impact on the RD optimization (RDO) of HEVC encoding, which results in a large amount of calculation costs in the operation of PU and TU size determination. Many research works focus on reducing the complexity through fast CU dividing and early skip in the stage of intra-slice coding. We propose a fast inter mode decision algorithm for the HEVC encode system in this paper, and a reformed early CU SKIP detection method constitutes this algorithm. For the current CU block that is being encoded, we use the related spatial coding parameters of CU to evaluate the texture complexity (TC) affecting the CU blocks that are being encoded. In addition, we utilize motion vectors, TU size, and block marking information to gauge the time complication of CU partitions. The proposed method efficiently uses the spatial coding parameters without additional computations. The proposed techniques reduce the encoding time significantly, by up to 47.9%, with an insignificant BD rate increase of about 1.6%.