* @param n the block index
* @param part_width the width of the partition (4, 8,16) -> (1, 2, 4)
* @param mx the x component of the predicted motion vector
* @param n the block index
* @param part_width the width of the partition (4, 8,16) -> (1, 2, 4)
* @param mx the x component of the predicted motion vector