Method for encoding and decoding motion information and device for encoding and decoding motion information
A method of decoding motion information according to an embodiment includes: determining a base motion vector of a current block; determining a primary differential motion vector for the current block based on information obtained from a bitstream from among one or more primary differential motion vector candidates classified according to a disparity distance and a disparity direction; and determining a motion vector of the current block by applying the primary differential motion vector to the base motion vector.
1. An apparatus for decoding motion information, the apparatus comprising:
an obtainer configured to parse a disparity distance index and a disparity direction index from a bitstream; and
a motion vector decoder configured to:
obtain a first motion vector difference for a first list from the disparity distance index and the disparity direction index,
if a current block is bi-predicted, derive a second motion vector difference for a second list, based on the first motion vector difference, 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,
obtain a first motion vector for the first list using the first motion vector difference and a first base motion vector for the first list,
obtain a second motion vector for the second list using the second motion vector difference and a second base motion vector for the second list, and
reconstruct the current block using the first motion vector, the first reference picture, the second motion vector and the second reference picture,
wherein the disparity distance index indicates a value of a power of 2.
2. An apparatus for encoding motion information, the apparatus comprising:
a motion vector encoder configured to:
obtain a first motion vector difference for a first list by using a first motion vector of a current block for the first list and a first base motion vector for the first list, and
if it is determined that the current block is to be bi-predicted, derive a second motion vector difference for a second list, based on the first motion vector difference, 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
a generator configured to generate a bitstream including a disparity distance index and a disparity direction index, the disparity distance index and the disparity direction index representing the first motion vector difference,
wherein the disparity distance index indicates a value of a power of 2.
3. A non-transitory computer-readable medium for recording a bitstream, the bitstream comprising:
a disparity distance index; and
a disparity direction index,
wherein the disparity distance index and the disparity direction index represents a first motion vector difference for a first list,
wherein the first motion vector difference for the first list is obtained by using a first motion vector of a current block for the first list and a first base motion vector for the first list,
wherein if it is determined that the current block is to be bi-predicted, a second motion vector difference for a second list is derived based on the first motion vector difference, 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 disparity distance index indicates a value of a power of 2.