CABAC context using left and above syntax elements

[bheng]

For Section 9.3.4.2.2, the following syntax elements seem to only be defined for CU location (x0, y0):

cu_skip_flag[x0][y0]
merge_subblock_flag[x0][y0]
inter_affine_flag[x0][y0]

Specifically, I haven't found text something like...

The following assignments are made for x = x0..x0 + cbWidth − 1 and y = y0..y0 + cbHeight − 1:

cu_skip_flag[x][y] = cu_skip_flag[x0][y0]
merge_subblock_flag[x][y] = merge_subblock_flag[x0][y0]
inter_affine_flag[x][y] = inter_affine_flag[x0][y0]

It's possible I may have overlooked that text somewhere. But if not, then it seems that the neighboring above/left locations [ xNbL ][ yNbL ] and [ xNbA ][ yNbA ] will never be set for Section 9.3.4.2.2.

[jlchen]

Good catch, you're right.

We usually don't make assignment to syntax element for this purpose. As done for other flags, three global variable arrays (e.g. CuSkipFlag, MergeSubblockFlag, InterAffineFlag) would be needed for the above three flags.

Beside in Section 9.3.4.2.2, inter_affine_flag[ xCb − 1 ][ yCb + y ] and merge_subblock_flag[ xCb − 1 ][ yCb + y ] are also used in section 8.8.3.4

[jlchen]

The issues will be fixed by defining three global arrays as mentioned above in the S2001-vH release.