Deblocking with ISP and Virtual Boundaries

[bheng]

The following code runs for each TU in an ISP CU. When the TU size is less than 4, this will set the same 4x4 block edge flag multiple times. If one of those TUs aligns with a virtual boundary (and the others do not), the additional ISP TUs will overwrite the edge flag, and the virtual boundary will be ignored.

for( auto &currTU : CU::traverseTUs( cu ) )
{

const Area& areaTu = cu.Y().valid() ? currTU.block( COMPONENT_Y ) : area;
verEdgeFilter = m_stLFCUParam.internalEdge;
horEdgeFilter = m_stLFCUParam.internalEdge;
if( isCuCrossedByVirtualBoundaries )
{

xDeriveEdgefilterParam( areaTu.x, areaTu.y, numVerVirBndry, numHorVirBndry, verVirBndryPos, horVirBndryPos, verEdgeFilter, horEdgeFilter );

}
xSetEdgefilterMultiple( cu, EDGE_VER, areaTu, verEdgeFilter );
xSetEdgefilterMultiple( cu, EDGE_HOR, areaTu, horEdgeFilter );
...

}

[XiangLi]

Fixed in ​https://vcgit.hhi.fraunhofer.de/jvet/VVCSoftware_VTM/merge_requests/1334