1. A method for encoding a picture, comprising: dividing a largest coding unit (LCU) of the picture into a plurality of motion estimation regions (MERs), a size of each of the MERs being equal to or less than a predetermined size; performing, for one or more MERs from among the plurality of MERs and with one or more processing circuits, a number of first motion searches so as to determine one or more first quad-trees, a first plurality of prediction units (PUs) being associated with each of the one or more MERs, each of the one or more first quad-trees being determined based on a first cost function associated with the first plurality of PUs; performing, for the LCU and with the one or more processing circuits, a number of second motion searches so as to determine a second quad-tree, a second plurality of PUs being associated with the LCU, and the second quad-tree being determined based on a second cost function associated with the second plurality of PUs; and selecting, with the one or more processing circuits, a quad-tree from among the one or more first quad-trees and the second quad-tree so as to implement an encoding device to encode the picture based on a comparison of a first cost of the one or more first quad-trees with a second cost of the second quad-tree, the first cost and the second cost being determined based on the first and second cost functions.