ph_virtual_boundaries_pos_x[i] specifies the location of the i-th vertical virtual boundary in units of luma samples divided by 8. The value of ph_virtual_boundaries_pos_x[i] shall be in the range of 1 to Ceil(pic_width_in_luma_samples÷8)?1, inclusive.
The list VirtualBoundariesPosX[i] for i ranging from 0 to NumVerVirtualBoundaries?1, inclusive, in units of luma samples, specifying the locations of the vertical virtual boundaries, is derived as follows:
for(i=0; i<NumVerVirtualBoundaries; i++)
VirtualBoundariesPosX[i]=(sps_virtual_boundaries_present_flag?
The distance between any two vertical virtual boundaries shall be greater than or equal to CtbSizeY luma samples.
ph_num_hor_virtual_boundaries specifies the number of ph_virtual_boundaries_pos_y[i] syntax elements that are present in the PH. When ph_num_hor_virtual_boundaries is not present, it is inferred to be equal to 0.
The parameter NumHorVirtualBoundaries is derived as follows:
NumHorVirtualBoundaries=0
if(sps_virtual_boundaries_enabled_flag)
NumHorVirtualBoundaries=sps_virtual_boundaries_present_flag?