A fast coding unit mode decision method based on the mode inheritance of upper coding unit for low-complexity compression of smart contents

Abstract

In combination with Internet-of-things (IoT) technology, realistic media will continue to evolve with more smart and intelligent media services via interactions between users and displays. Therefore, it is important to efficiently compress smart contents on low-power and low-complexity hand-held displays. High efficiency video coding (HEVC) is the latest video coding technology that can achieve excellent coding performance, but at the cost of tremendously increased complexity due to the use of newly adopted video coding tools. Most previous fast encoding methods were mainly investigated in terms of spatio-temporal correlation between the current coding unit (CU) and neighboring CUs. As HEVC has a recursive quad-tree structure, the correlation between different CU depths can be higher than the spatio-temporal correlation. In this study, a fast CU mode decision method is proposed for estimating the mode of a current CU to be encoded either as intra or inter mode prior to encoding a current CU. The method uses the information of the best upper CU mode, where an upper CU indicates a larger block than a current CU in the quad-tree structure. The experimental results show that the encoding process of the proposed method is faster than that of a previous method with an unnoticeable coding loss.