When the current subpicture has sps_subpic_treated_as_pic_flag equal to
1, motion vectors are cropped such that they cannot point to other
subpictures. This was accounted for in the prediction logic, but not
in pred_get_y, which is used by the scheduling logic to determine which
parts of the reference pictures must have been reconstructed before
inter prediction of a subsequent frame may begin. Consequently, where a
motion vector pointed to a location significantly above the current
subpicture, there was the possibility of a race condition. Patch fixes
this by cropping the motion vector to the current subpicture in
pred_get_y.
Signed-off-by: Frank Plowman <post@frankplowman.com>
539cea3183