The Optimization of Adaptive Loop Filter Based on the Reduction of the Filter Sets

Based on High Efficiency Video Coding (H.265/HEVC), Versatile Video Coding (H.266/VVC) proposed a new loop filtering technology-adaptive loop filter (ALF). ALF brings better coding performance to the encoder, but it also increases the coding complexity. To solve this problem, this paper proposes an ALF optimization algorithm. By reducing the filter sets including the fixed filter sets and the adaptation parameter set (APS) filter sets, the computational complexity of rate-distortion optimization (RDO) for ALF filter sets is reduced. VVenC is the open-source and efficient encoder of H.266/VVC. The performance of the algorithm is tested on VVenC set to medium preset and fast preset in RA mode. The experimental results show that the proposed algorithm can reduce the time by 8.64% on average, while the BD-Rate is only reduced by 0.08% in fast preset.