Arrangement of adaptive loop filter coefficients for fast vectorized transpositions

A method of video encoding performed in a video encoder, the method comprising:

• grouping a plurality of coefficients of a filter with a central symmetric shape into a plurality of groups based on a transposition operation to be performed on the filter, each of the plurality of coefficients being associated with a respective first coordinate value along a first axis and a respective second coordinate value along a second axis, and the coefficients in each of the plurality of groups being a same distance from a center position of the filter and stored in a respective same chunk of contiguous memory;
• reordering the coefficients of a first group of the plurality of groups based on the transposition operation;
• applying the filter with the central symmetric shape to a current block in a current picture based on the reordered coefficients of the filter;
• and
• encoding, in a bitstream, coding information indicating that the filter with the central symmetric shape is applied to the current block.

A method of processing visual media data, the method comprising:

• processing a bitstream that includes the visual media data according to a format rule, wherein
• the bitstream includes prediction information of a current block in a current picture, the prediction information indicating that a filter with a central symmetric shape is applied to the current block, the filter including a plurality of coefficients, each of the plurality of coefficients being associated with a respective first coordinate value along a first axis and a respective second coordinate value along a second axis;
• and
• the format rule specifies that
• the plurality of coefficients of the filter is grouped into a plurality of groups based on a transposition operation to be performed on the filter, the coefficients in each of the plurality of groups being a same distance from a center position of the filter and stored in a respective same chunk of contiguous memory;
• the coefficients of a first group of the plurality of groups are reordered based on the transposition operation;
• and
• filtered samples of the current block are processed by applying the filter with the central symmetric shape to the current block based on the reordered coefficients of the filter.