id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc
1168	Mismatch between the VVC spec draft and VTM: bugs in equations (335) and (345)	afilippov		"The following two pieces of specification do not match with the VTM SW. The bug is in the negative value of x in expression ""x * invAngle + 256"" of equations (335) and (345)

–	If intraPredAngle is less than 0, the main reference sample array is extended as follows:
ref[ x ] = p[ −1 − refIdx ][ −1 − refIdx + Min( ( x * invAngle + 256 )  >>  9, nTbH ) ],
	with x = −nTbH..−1	(335)

–	If intraPredAngle is less than 0, the main reference sample array is extended as follows:
ref[ x ] = p[ −1 − refIdx + Min( ( x * invAngle + 256 )  >>  9, nTbW ) ][ −1 − refIdx ],
	with x = −nTbW..−1	(345)

Please, compare with VTM:

 
{{{
   int sizeSide = bIsModeVer ? height : width;
    for (int k = -sizeSide; k <= -1; k++)
    {
      refMain[k] = refSide[std::min((-k * invAngle + 256) >> 9, sizeSide)];
    }

}}}

Two alternative fixes are suggested:

1. Substitute ""x"" with ""-x"" inside ""Min()"":
 
–	If intraPredAngle is less than 0, the main reference sample array is extended as follows:
ref[ x ] = p[ −1 − refIdx ][ −1 − refIdx + Min( ( (-x) * invAngle + 256 )  >>  9, nTbH ) ],
	with x = −nTbH..−1	(335)

2.  Substitute ""x"" with ""-x"" in the result indexing and negate the x range defined in ""with x=..."" part:
– If intraPredAngle is less than 0, the main reference sample array is extended as follows:
ref[ -x ] = p[ −1 − refIdx ][ −1 − refIdx + Min( ( x * invAngle + 256 )  >>  9, nTbH ) ],
	with x = 1..nTbH	(335)"	defect	closed	minor		spec		invalid		ksuehring bbross XiangLi fbossen jvet@…