Modified adaptive loop filter temporal prediction for temporal scalability support

A method of decoding video data, the method comprising:

• receiving a bitstream that includes an encoded representation of a current picture of the video data, wherein a current region of the current picture is associated with a first temporal index indicating a first temporal layer to which the current region belongs;
• reconstructing the current picture;
• when a set of adaptive loop filtering (ALF) parameters of sets of ALF parameters used in applying ALF filters to samples of regions of pictures of the video data that are decoded prior to the current region are in the first temporal layer corresponding to the first temporal index, storing the set of ALF parameters in stored sets of ALF parameters;
• when a set of ALF parameters of the sets of ALF parameters are in a temporal layer corresponding to a temporal index that is lower than the first temporal index, storing the set of ALF parameters in the stored sets of ALF parameters;
• determining, based on a selected set of ALF parameters of the stored sets of ALF parameters, an applicable set of ALF parameters for the current region;
• and
• applying, based on the applicable set of ALF parameters for the current region, adaptive loop filtering to the current region.

A non-transitory computer-readable data storage medium storing instructions that, when executed, cause a processor to:

• receive a bitstream that includes an encoded representation of a current picture of the video data, wherein a current region of the current picture is associated with a first temporal index indicating a first temporal layer to which the current region belongs;
• reconstruct the current picture;
• when a set of adaptive loop filtering (ALF) parameters of sets of ALF parameters used in applying ALF filters to samples of regions of pictures of the video data that are decoded prior to the current region are in the first temporal layer corresponding to the first temporal index, store the set of ALF parameters in stored sets of ALF parameters;
• when a set of ALF parameters of the sets of ALF parameters are in a temporal layer corresponding to a temporal index that is lower than the first temporal index, store the set of ALF parameters in the stored sets of ALF parameters;
• determine, based on a selected set of ALF parameters of the stored sets of ALF parameters, an applicable set of ALF parameters for the current region;
• and
• apply, based on the applicable set of ALF parameters for the current region, adaptive loop filtering to the current region.