Video signal encoding and decoding method, and apparatus therefor

A video encoding method comprising the steps of:

• generating a merge candidate list for a current block;
• selecting a merge candidate for the current block among merge candidates included in the merge candidate list;
• deriving an offset vector for the current block;
• wherein a range of motion vector offset size candidates is set differently based on a motion vector precision;
• encoding first index information for specifying a motion magnitude candidate indicating a magnitude of the offset vector among a plurality of motion magnitude candidates,
• wherein the motion magnitude candidate has a value derived by applying a logical shift operation to the magnitude of the offset vector;
• and
• deriving a motion vector for the current block by adding the offset vector to a motion vector of the merge candidate.

A video decoding device comprising:

• a memory module storing instructions;
• a processing unit configured to, upon executing the instructions:
• generate a merge candidate list for a current block, determine a merge candidate for the current block among merge candidates included in the merge candidate list, derive an offset vector for the current block, and derive a motion vector for the current block by adding the offset vector to a motion vector of the merge candidate;
• wherein a range of motion vector offset size candidates is set differently based on a motion vector precision,
• wherein a magnitude of the offset vector is determined based on first index information specifying one among motion magnitude candidates,
• wherein the magnitude of the offset vector is obtained by applying a logical shift operation to a value indicated by the motion magnitude candidate specified by the first index information.