US 11,838,557 B2
Methods and apparatuses of ALF derivation in video encoding system
Shih-Chun Chiu, Hsinchu (TW); Chih-Wei Hsu, Hsinchu (TW); Ching-Yeh Chen, Hsinchu (TW); Chun-Chia Chen, Hsinchu (TW); Tzu-Der Chuang, Hsinchu (TW); and Yu-Wen Huang, Hsinchu (TW)
Assigned to MEDIATEK INC., Hsinchu (TW)
Filed by MEDIATEK INC., Hsinchu (TW)
Filed on Apr. 22, 2022, as Appl. No. 17/726,713.
Claims priority of provisional application 63/280,174, filed on Nov. 17, 2021.
Prior Publication US 2023/0156234 A1, May 18, 2023
Int. Cl. H04N 19/82 (2014.01); H04N 19/117 (2014.01); H04N 19/124 (2014.01); H04N 19/186 (2014.01); H04N 19/147 (2014.01)
CPC H04N 19/82 (2014.11) [H04N 19/117 (2014.11); H04N 19/124 (2014.11); H04N 19/147 (2014.11); H04N 19/186 (2014.11)] 15 Claims
OG exemplary drawing
 
1. A video encoding method for an Adaptive Loop Filter (ALF) clipping index optimization process in a video encoding system, comprising:
receiving reconstructed video samples;
determining an initial clipping setting for ALF coefficients;
deriving a plurality of clipping setting candidates from the initial clipping setting;
deriving ALF coefficients for a plurality of clipping settings by solving inverse matrices for ALF coefficients, wherein the clipping settings include the initial clipping setting and clipping setting candidates, and partial intermediate results of solving ALF coefficients are shared by two or more clipping settings;
calculating a distortion value corresponding to the derived ALF coefficients for each of the clipping settings;
determining final clipping indices for final ALF coefficients according to the distortion values, wherein determining final clipping indices for final ALF coefficients comprises comparing the distortion values associated with the clipping settings, selecting a clipping setting having a minimum distortion value, and
determining the final clipping indices to be clipping indices of the clipping setting having the minimum distortion value, or
determining clipping indices of the initial clipping setting to be the final clipping indices when the clipping setting having the minimum distortion value is the initial clipping setting, and determining an initial clipping setting for a subsequent iteration of the ALF clipping index optimization process to be the clipping setting having the minimum distortion value when the clipping setting having the minimum distortion value is one of the clipping setting candidates; and
applying ALF filtering to the reconstructed video samples based on the final ALF coefficients and the final clipping indices.