JVET-R0168 Issue on bS derivation of deblocking filter [K. Abe, T. Toma (Panasonic)]
This contribution points out the mismatch between VVC text and VTM on bS derivation process of deblocking filter. In VVC text, bS is set equal to 1 for the boundary between IBC and inter block on both luma edge and chroma edge. On the other hand, in VTM, bS is set equal to 1 for the boundary between IBC and inter block only on luma edge. The proponent of this contribution thinks there are two solutions, solution1: fix VTM to align to VVC text, solution2: fix VVC text to align to VTM. This contribution shows the difference of coding performance and text changes for both solutions.
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It is mentioned by the proponents that solution 1 would have small impact on coding results, therefore they would better suggest aligning the text with software.
Several experts expressed support for solution 2, as also in the past it had been agreed that MV differences should not be checked for chroma deblocking.
AHG Recommendation (mismatch/align text): The proposed text changes should be adopted. There may however be some interaction with a related issue in JVET-R0228, where palette mode is also considered. See further notes under JVET-R0437.