Fast H.266/VVC Intra Coding by Early Skipping Joint Coding of Chroma Residuals

Abstract

Versatile Video Coding (H.266/VVC) significantly enhances compression performance but also increases encoding complexity. Numerous fast intra coding algorithms have been proposed to balance the performance gains with the increased complexity introduced by various advanced tools. However, few fast algorithms are specific to Joint Coding of Chroma Residuals (JCCR), a newly introduced technique that requires additional rate-distortion optimization (RDO) processes. To address this gap, this letter introduces a fast intra coding algorithm that reduces complexity by early skipping unnecessary JCCR. Specifically, we propose skipping JCCR when the correlation between chroma components is low, and we construct a JCCR normalized reconstruction distortion to measure this correlation. The skip conditions are determined by statistical analysis, intelligently reducing the number of RDO processes for chroma components. Experimental results show that, compared to the Fraunhofer Versatile Video Encoder (VVenC), our algorithm achieves encoding time savings of 1.68% and 2.82% under Random Access (RA) and All Intra (AI) settings, respectively, with a performance loss of 0.03% and 0.09% only, demonstrating the effectiveness of our fast algorithm.