Search region for motion vector refinement

An apparatus for determining a refinement motion vector to be used in inter-prediction of a current block of a video frame, the apparatus comprising:

• a search space determining unit configured to:
• obtain an initial motion vector,
• determine a first search space based on the initial motion vector, wherein a plurality of candidate motion vectors is comprised in the first search space, and wherein the first search space has an integer pixel resolution,
• determine a candidate motion vector in the first search space according to a cost function, and
• determine a second search space based on the determined candidate motion vector, wherein one or more additional candidate motion vectors is comprised in the second search space, and wherein the second search space has a fractional pixel resolution;
• and
• a motion vector selecting unit configured to obtain the refinement motion vector for a current block according to the plurality of candidate motion vectors of the first search space and the one or more additional candidate motion vectors of the second search space.