A method of processing video data, the method comprising: splitting a current block of video data of a current picture into a plurality of sub-blocks for deriving motion information of the current block, wherein the motion information indicates motion of the current block relative to reference video data, and wherein splitting the current block comprises i) splitting the current block to form sub-blocks of a fixed size regardless of the size of the current block, or ii) splitting the current block based on a minimum sub-block size determined based on a split depth parameter D that indicates a maximum split depth for the current block; deriving motion information for the whole current block by performing a motion search for a respective first set of reference video data of a reference picture based on a respective second set of reference video data, the respective second set of reference video data being outside of the current block, wherein the second set of reference data is either of the current picture or of a second reference picture; deriving, separately for each respective sub-block of the plurality of sub-blocks, motion information, the deriving comprising performing a motion search for a respective third set of reference video data of a reference picture based on a respective fourth set of reference video data, the respective fourth set of reference video data being outside of the respective sub-block, and wherein the search is performed by setting the motion information for the whole current block as the search center and then refining the motion for each sub-block; applying a transform to the current block so that the transform crosses sub-block boundaries; and decoding the plurality of sub-blocks based on the derived motion information and without decoding syntax elements representative of the motion information. splitting a current block of video data of a current picture into a plurality of sub-blocks for deriving motion information of the current block, wherein the motion information indicates motion of the current block relative to reference video data, and wherein splitting the current block comprises i) splitting the current block to form sub-blocks of a fixed size regardless of the size of the current block, or ii) splitting the current block based on a minimum sub-block size determined based on a split depth parameter D that indicates a maximum split depth for the current block; deriving motion information for the whole current block by performing a motion search for a respective first set of reference video data of a reference picture based on a respective second set of reference video data, the respective second set of reference video data being outside of the current block, wherein the second set of reference data is either of the current picture or of a second reference picture; deriving, separately for each respective sub-block of the plurality of sub-blocks, motion information, the deriving comprising performing a motion search for a respective third set of reference video data of a reference picture based on a respective fourth set of reference video data, the respective fourth set of reference video data being outside of the respective sub-block, and wherein the search is performed by setting the motion information for the whole current block as the search center and then refining the motion for each sub-block; applying a transform to the current block so that the transform crosses sub-block boundaries; and decoding the plurality of sub-blocks based on the derived motion information and without decoding syntax elements representative of the motion information.