[geo partitioning] 8.5.7.2 implementation : Diff VTM versus spec ?

[fbarbier]

In 8.5.7.2, equation 1015 (spec JVET-S2001-vC)

offset1 = 1 << ( shift1 − 1 )

In VTM code (source/Lib/CommonLib/InterpolationFilter.cpp):

offsetWeighted = (1 << (shiftWeighted - 1)) + (IF_INTERNAL_OFFS << log2WeightBase);

That's seems to match something like :

offset1 = (1 << (shift1 - 1)) + (32 << 3);

Am i missing something ? Is is due to an offset on the pixels elsewhere?

[fbossen]

Intermediate values in the MC process are offset by -IF_INTERNAL_OFFS such as to avoid overflows when using 16-bit signed values for storage. This offset has to be removed when computing the final prediction values.
BTW, IF_INTERNAL_OFFS should be 8192, not 32.

[fbarbier]

ok ! thanks for the information !