Short-Distance Intra Prediction of Screen Content in Versatile Video Coding (VVC)

A novel intra prediction algorithm is proposed to improve the coding performance of screen content for the emerging Versatile Video Coding (VVC) standard. The algorithm, called in-loop residual coding with scalar quantization, employs in-block pixels as reference rather than the regular out-block ones. To this end, an additional in-loop residual signal is used to partially reconstruct the block at the pixel level, during the prediction. The proposed algorithm is essentially designed to target high detail textures, where deep block partitioning structure is required. Therefore, it is implemented to operate on 4× 4 blocks only, where further block split is not allowed and the standard algorithm is still unable to properly predict the texture. Experiments in the Joint Exploration Model (JEM) reference software show that the proposed algorithm brings a Bjontegaard Delta (BD)-rate gain of 13% on synthetic content, with a negligible computational complexity overhead at both encoder and decoder sides.