Several methods and systems for encoding pictures are disclosed. In an embodiment, a method comprises dividing an LCU of a picture into a plurality of MERs having size equal to or less than a predetermined size. For one or more MERs of the plurality of MERs, a number of first motion searches are performed for determining a first quad-tree based on a cost function associated with a first plurality of PUs of the one or more MERs. A number of second motion searches are performed for the LCU, for determining a second quad-tree, based on the cost function associated with a second plurality of PUs of the LCU. The first quad-tree or the second quad-tree is selected for performing encoding of the picture based on a comparison of a first cost of the first quad-tree with a second cost of the second quad-tree.