1. A method for encoding video data, the method comprising: generating a motion vector (MV) candidate list for a prediction unit (PU) of a coding unit (CU) in a B slice; after generating the MV candidate list, determining a selected MV candidate in the MV candidate list; after determining the selected MV candidate, converting the selected MV candidate from a bi-directional MV candidate into a uni-directional MV candidate; after converting the selected MV candidate into the uni-directional MV candidate, assigning the uni-directional MV candidate to the PU; generating a predictive video block for the PU based at least in part on one or more reference blocks of decoded reference pictures, the one or more reference blocks indicated by motion information specified by the selected MV candidate; using the uni-directional MV candidate assigned to the PU for merge candidate list construction or advanced motion vector prediction (AMVP) candidate list construction for a next block in coding order; and outputting encoded video data based at least in part on the predictive video block.
4. The method of claim 1 , wherein converting the selected MV candidate comprises converting the selected MV candidate into the uni-directional MV candidate only when motion information of the PU is signaled using AMVP mode.