id summary reporter owner description type status priority milestone component version resolution keywords cc 551 Misalignment between Spec and VTM sw on ALF clipping value derivation du757372199 "In VVC Spec D6-vE, the ALF clipping values for chroma are derived using the following texts: '''alf_chroma_clip_idx[ altIdx ][ j ] specifies the clipping index of the clipping value to use before multiplying by the j-th coefficient of the alternative chroma filter with index altIdx. It is a requirement of bitstream conformance that the values of alf_chroma_clip_idx[ altIdx ][ j ] with altIdx = 0..alf_chroma_num_alt_filters_minus1, j = 0..5 shall be in the range of 0 to 3, inclusive. The chroma filter clipping values AlfClipC[ adaptation_parameter_set_id ][ altIdx ] with elements AlfClipC[ adaptation_parameter_set_id ][ altIdx ][ j ], with altIdx = 0..alf_chroma_num_alt_filters_minus1, j = 0..5 are derived as specified in Table 7 4 depending on bitDepth set equal to BitDepthC and clipIdx set equal to alf_chroma_clip_idx[ altIdx ][ j ].''' However, the Table 7-4 is only used for luma in VTM-6.0, and for chroma, a separate look-up table should be applied as implemented in VTM-6 as well as proposed in JVET-N0242. To align VTM-6 and JVET-N0242, It is suggested to fix the Spec text and use two separate table for deriving the ALF clipping values for luma and chroma." defect closed minor VTM VVC D7 vC wontfix ksuehring bbross XiangLi fbossen jvet@…