Chroma Deblocking Issues with Max Transform Size

[bheng]

In function LoopFilter::xDeblockCU()

a.) This line calculates the area of all TU from a CHROMA_TREE CU as always equal to the CU size.

const Area& areaTu = cu.Y().valid() ? currTU.block( COMPONENT_Y ) : area;

The calculation should be based on the actual chroma TU size in case of max-transform-size split TUs.

b.) This line assumes all TU/CU sizes are in luma pixel units.

edgeIdx.push_back( ( edgeDir == EDGE_HOR ) ? ( currTU.blocks[cu.chType].y - cu.blocks[cu.chType].y ) / 4 : ( currTU.blocks[cu.chType].x - cu.blocks[cu.chType].x ) / 4 );

When chType is chroma, the calculations should be scaled by SubWidthC and SubHeightC.

[XiangLi]

Fixed in ​https://vcgit.hhi.fraunhofer.de/jvet/VVCSoftware_VTM/merge_requests/1335