Inter-prediction method and apparatus for same

A method for decoding a video signal based on inter prediction, the method comprising:

• obtaining a residual block for a current block by decoding an input bitstream;
• generating a merge candidate list of the current block by using neighboring blocks adjacent to the current block, each of the neighboring blocks having motion information;
• deriving, based on a merge index, motion information of a current block from the merge candidate list, the merge index specifying a merge candidate included in the merge candidate list;
• generating a prediction block for the current block based on the derived motion information;
• and
• reconstructing the current block by adding the residual block to the prediction block,
• wherein the derived motion information comprises prediction direction information and both of L0 motion information and L1 motion information,
• wherein, in response to the prediction direction information of the current block indicating a bi-prediction and a size of the current block being smaller than a pre-determined size, the prediction direction information indicating the bi-prediction is changed to indicate a uni-prediction and the prediction block of the current block is generated by performing motion compensation based on only the L0 motion information among the L0 motion information and the L1 motion information,
• wherein, in response to the prediction direction information indicating the bi-prediction and the size of the current block being equal to or greater than the pre-determined size, the prediction direction information indicating the bi-prediction is not changed to indicate the uni-prediction and the prediction block of the current block is generated by performing the motion compensation based on both the L0 motion information and the L1 motion information, and
• wherein the pre-determined size is representative of one of 8×8, 16×16, or 32×32.