Local-Aware Intra Block Copy for Video Coding
Yang Wang, Kai Zhang, Li Zhang · 2023
Intra block copy is an efficient coding tool for screen content video, in which the prediction is obtained from a reference block within the same picture indicated by a block vector. Since repetitive textures typically exist in the screen content video, the non-local information used in IBC can improve coding performance significantly. However, the local information thoroughly investigated in intra prediction has not been explored in IBC. In this paper, local-aware intra block copy (LA-IBC) is proposed to further improve the coding performance of IBC. LA-IBC is composed of three methods. First, combined IBC and intra prediction (IBC-CIIP) is proposed to fuse the two prediction signals generated by IBC and intra prediction. Second, IBC with geometry partitioning (IBC-GPM) is proposed, in which a block is divided into two sub-partitions geometrically and IBC and intra prediction are used to obtain their prediction signals, individually. Third, IBC with local illumination compensation (IBC-LIC) is proposed to explore the illumination variation between the local and non-local templates within the picture. LA-IBC is integrated in the latest exploration software of video coding (Enhanced Compression Model, ECM) published by JVET to evaluate its efficiency. The experimental results demonstrate that LA-IBC can achieve 1.7% and 0.88% Bjontegaard Delta rate (BD-rate) saving for screen content video compared to ECM-6.0 under all intra and random access configurations, respectively.