Improved intra-subpartition coding mode for versatile video coding

The newest state-of-the-art video coding standard, which is versatile video coding, is now ready after the joint call for proposals provided by ITU-T VCEG and ISO/IEC MPEG. This fresh video coding standard enables superior compression efficiency compared to its competitors, thanks to the new efficient coding tools such as block partitioning, intra–inter-prediction, entropy coding and residue transform. This paper focuses on intra-coding mode to improve coding efficiency of the new generation video coding standard. The proposed method is based on intra-subpartition coding mode, which is an extended version of the line-based intra-prediction mode. In order to obtain a better coding gain, an adaptive subpartition mechanism is introduced instead of a fixed number of subpartitions. According to the experimental results bitrate savings, up to 0.95%, are obtained compared to the reference software VTM11.0 under all-intra-configuration mode. Experimental findings also show that the contents of the blocks to be coded are directly related to the number of subpartitions.