Systems and methods for applying deblocking filters to reconstructed video data

A method of deblock filtering adjacent video data blocks in a video picture, the method comprising:

• for each pair of adjacent video blocks:
• receiving component color values for each video block in the pair;
• determining whether a set of one or more conditions associated with the pair of adjacent video blocks are satisfied, the set of conditions comprising one or more conditions relating to sizes of the video blocks in the pair;
• selecting, from a plurality of candidate filters to apply to chroma component color values of the pair of adjacent video blocks, one filter based on the determination of whether the set of one or more conditions is satisfied;
• using the selected filter to modify the chroma component color values in the pair of adjacent video blocks;
• wherein for a first pair of adjacent video blocks that share a horizontal boundary, the plurality of candidate filters comprises (i) a first filter for modifying chroma component color values in rows of chroma component color values, the rows including rows in each video block in the first pair, and (ii) a second filter for modifying chroma component color values in one row that is adjacent to the horizontal boundary in each video block in the first pair;
• and
• wherein when the pair of adjacent video blocks share a horizontal boundary, using the selected filter to modify the chroma component color values of the pair of adjacent video blocks comprises:
• using the first filter to modify at least three rows in a first video block of the pair based on:
• at least four rows of the first video block of the pair, and
• at least two rows of a second video block of the pair;
• and
• using the first filter to modify at least three rows of the second video block based on:
• at least four rows of the second video block, and
• at least two rows of the first video block.