* second dimension: 0 if no vertical interpolation is needed;
* 1 4-tap vertical interpolation filter (my & 1)
* 2 6-tap vertical interpolation filter (!(my & 1))
* second dimension: 0 if no vertical interpolation is needed;
* 1 4-tap vertical interpolation filter (my & 1)
* 2 6-tap vertical interpolation filter (!(my & 1))