Typos in the derivation of neighbouring luma samples of CCLM

[wangyang.cs]

Two typos exist in JVET-Q2001-vE:

1. When availT is equal to FALSE, numSampT is equal to 0. When availL is equal to FALSE, numSampL is equal to 0.
2. 2-tap filter in CCLM will never be used.

Suggest changes in JVET-Q2001-vE as follows:

8.4.5.2.13 Specification of INTRA_LT_CCLM, INTRA_L_CCLM and INTRA_T_CCLM intra prediction mode

2. The neighbouring luma samples pY[ x ][ y ] are derived as follows:

– When numSampL is greater than 0, the neighbouring left luma samples pY[ x ][ y ] with x = −1..− 3, y = 0..SubHeightC * numSampL − 1, are set equal to the reconstructed luma samples prior to the deblocking filter process at the locations ( xTbY + x , yTbY +y ).

– When availT is equal to FALSE, the neighbouring top luma samples pY[ x ][ y ] with x = −1..SubWidthC * numSampTnTbW − 1, y = −1..−2, are set equal to the luma samples pY[ x ][ 0 ].

– When availL is equal to FALSE, the neighbouring left luma samples pY[ x ][ y ] with x = −1..−3, y = −1..SubHeightC * numSampLnTbH − 1, are set equal to the luma samples pY[ 0 ][ y ].

...

– The one-dimensional filter coefficients array F1 and F2, and the 2-dimensional filter coefficients arrays F3 and F4 are specified as follows.

F1[ 0 ] = 2, F1[ 1 ] = 0 (361)

F2[ 0 ] = 1, F2[ 1 ] = 2, F2[ 2 ] = 1 (362)
F3[ i ][ j ] = F4[ i ][ j ] = 0, with i = 0..2, j = 0..2 (363)

– If both SubWidthC and SubHeightC are equal to 2, the following applies:

F1[ 0 ] = 1, F1[ 1 ] = 1 (364)

[bbross]

Good catch, thanks!

This is fixed in vB of D9, ie. JVET-R2001-v11.