Method for encoding and decoding motion information, and apparatus for encoding and decoding motion information
A method of decoding motion information according to an embodiment includes: obtaining information indicating a disparity distance for determining a prediction motion vector of a current block; scaling the disparity distance corresponding to the obtained information, based on a comparison result between a base pixel unit and a smallest pixel unit indicatable by a motion vector of the current block; determining a prediction motion vector candidate changed by the scaled disparity distance from a base motion vector of the current block from among one or more prediction motion vector candidates as the prediction motion vector of the current block; and determining the motion vector of the current block by using the prediction motion vector.
1. A method of decoding motion information, the method comprising:
obtaining, from a bitstream, information about a precision of a pixel unit in a predetermined mode;
obtaining, from the bitstream, information indicating a disparity distance for a current block;
obtaining, from the bitstream, information indicating a disparity direction for the current block;
if the precision of the pixel unit is a predetermined precision, determining a first disparity distance based on the obtained information indicating the disparity distance;
if the precision of the pixel unit is not the predetermined precision, determining a second disparity distance based on the obtained information indicating the disparity distance; and
if the current block is bi-predicted:
determining a first motion vector for a first list of the current block by changing a first base motion vector for the first list by a first offset, wherein the first offset has a size corresponding to the first disparity distance or the second disparity distance, and a sign of the first offset corresponds to the information indicating the disparity direction;
determining a second offset by scaling the first offset based on a picture order count (POC) of a current picture, a POC of a first reference picture in the first list, and a POC of a second reference picture in a second list of the current block; and
determining a second motion vector for the second list of the current block by changing a second base motion vector for the second list by the second offset,
wherein the second disparity distance is larger than the first disparity distance.
2. A method of encoding motion information, the method comprising:
determining a precision of a pixel unit in a predetermined mode;
if a current block is bi-predicted, determining a first base motion vector for a first list and a second base motion vector for a second list of the current block;
determining a first offset corresponding to a difference between the first base motion vector and a first motion vector for the first list of the current block; and
generating a bitstream comprising information about the precision of the pixel unit, information indicating a disparity distance corresponding to a size of the first offset and information indicating a disparity direction corresponding to a sign of the first offset,
wherein if the precision of the pixel unit is a predetermined precision, the information indicating the disparity distance indicates a first disparity distance, if the precision of the pixel unit is not the predetermined precision, the information indicating the disparity distance indicates a second disparity distance,
wherein a second offset corresponding to a difference between the second base motion vector and a second motion vector for the second list of the current block is determined by scaling the first offset based on a picture order count (POC) of a current picture, a POC of a first reference picture in the first list, and a POC of a second reference picture in the second list, and
wherein the second disparity distance is larger than the first disparity distance.