Encoding method and device thereof, and decoding method and device thereof

A video encoding method comprising:

• generating correction distance range information indicating one of a plurality of correction distance candidate sets;
• determining a motion vector of a current block;
• determining a current correction distance and a current correction direction to represent the motion vector of the current block from a base motion vector;
• generating information about a correction distance for indicating the current correction distance based on a correction distance set;
• generating information about a correction direction for indicating the current correction direction;
• and
• outputting a bitstream comprising the correction distance range information, the information about the correction distance, and the information about the correction direction,
• wherein:
• one correction distance set from among the plurality of correction distance candidate sets comprises a preset number of correction distance candidates,
• the correction distance set is one among the plurality of correction distance candidate sets,
• the information about the correction distance indicates the correction distance among the preset number of correction distance candidates included in the correction distance set, and
• a first correction distance candidate set, among the plurality of correction distance candidate sets, includes correction distance candidates {1, 2}, and a second correction distance candidate set, among the plurality of correction distance candidate sets, does not include the correction distance candidates {1, 2}.

A non-transitory computer readable storage medium storing a bitstream generated by a video encoding method, the bitstream comprising:

• correction distance range information indicating one of a plurality of correction distance candidate sets;
• information about a correction distance for indicating a current correction distance based on a correction distance set;
• and
• information about a correction direction for indicating a current correction direction,
• wherein the video encoding method comprises:
• generate the correction distance range information;
• determine a motion vector of a current block;
• determine the current correction distance and the current correction direction to represent the motion vector of the current block from a base motion vector;
• generate the information about the correction distance for indicating the current correction distance based on the correction distance set;
• generate the information about the correction direction for indicating the current correction direction;
• and
• output the bitstream comprising the correction distance range information, the information about the correction distance, and the information about the correction direction,
• wherein:
• one correction distance set from among the plurality of correction distance candidate sets comprises a preset number of correction distance candidates,
• the correction distance set is one among the plurality of correction distance candidate sets,
• the information about the correction distance indicates the correction distance among the preset number of correction distance candidates included in the correction distance set, and
• a first correction distance candidate set, among the plurality of correction distance candidate sets, includes correction distance candidates {1, 2}, and a second correction distance candidate set, among the plurality of correction distance candidate sets, does not include the correction distance candidates {1, 2}.