1. A method for coding video data, the method comprising: generating a prediction block for a coding unit (CU) of a frame of the video data, the CU having a plurality of prediction units (PUs) that includes a first PU and a second PU, the CU being either a uni-prediction CU or a bi-prediction CU, the prediction block including a transition zone at a boundary between samples of the prediction block associated with the first PU of the CU and samples of the prediction block associated with the second PU of the CU, wherein generating the prediction block comprises: when the CU is a uni-prediction CU, searching a single reference frame for a reference sample of a given PU of the CU, the given PU being either the first PU or the second PU; when the CU is a bi-prediction CU, searching two reference frames to obtain two reference samples for the given PU of the CU; and using the reference sample or reference samples of the given PU to generate a portion of the prediction block for the CU; making, by a computing device, a determination, based on a size of the first PU and based on whether the CU is a uni-prediction CU or a bi-prediction CU, whether to perform an Overlapped-Block Motion Compensation (OBMC) smoothing operation; and when the computing device makes the determination to perform the OBMC smoothing operation, performing the OBMC smoothing operation to smooth samples of the prediction block that are within the transition zone.