Fast HEVC intra mode decision algorithm based on new evaluation order in the Coding Tree Block

This paper presents a fast mode decision algorithm for the HEVC intra prediction. A new evaluation order in the Coding Tree Block (CTB) allows the use of modes from low level PUs to be used as reference to the current PU decision. In this paper we use this idea to develop a fast intra mode decision algorithm that can be configured to run in two different complexity modes, relaxed and aggressive. Experimental results have shown that our algorithm achieved encoding time savings of almost 60% with negligible loss in the compression efficiency when compared to the full RDO based decision. Besides, our mode decision algorithm presented the best result in terms of time saving per compression efficiency when compared with all related works.