id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc
338	transform depth 0 is used in coding tu_cbf_cb for CU using SBT	zhaoyin		"The removal of hierarchical signaling of cbf_cb and cbf_cr creates a bug in VTM5.0. When SBT is used for a CU, cbf_cb and cbf_cr is signaled at transform depth 0 in VTM5.0 (still in transform_tree()), but they shall be signaled at transform depth 1 according to the spec (in transform_unit()). Because the cbf_cb context modeling depends on transform depth, VTM5 is not equivalent to spec on cbf_cb when SBT is used. 

To better understand this issue, a part of the fix is provided as follows.
{{{ #!C++
#if FIX_SBT_CBF
        if( !(cu.sbtInfo && (trDepth == 0 
          | |  (trDepth == 1 && partitioner.currPartIdx() != cu.getSbtPos()))) )
#else
        if (!(cu.sbtInfo && trDepth == 1))
#endif
          chromaCbfs.Cb &= cbf_comp(cs, area.blocks[COMPONENT_Cb], cbfDepth);
}}}
By this fix, the CTC RA BD-rate change is 0.01% /-0.01% / -0.05%."	defect	closed	minor		VTM	VTM-5.0	fixed	cbf	ksuehring XiangLi fbossen jvet@…