Method for selecting motion vector predictor and device using same
A method for selecting a motion vector predictor is provided. The method of selecting a motion vector predictor includes the steps of selecting motion vector predictor candidates for a current block and selecting a motion vector predictor of the current block out of the motion vector predictor candidates, wherein the motion vector predictor candidates for the current block include a motion vector of a first candidate block which is first searched for as an available block out of left neighboring blocks of the current block and a motion vector of a second candidate block which is first searched for as an available block out of upper neighboring blocks of the current block.
1. A method of decoding video, comprising:
deriving, by a decoding apparatus, a first motion vector predictor (MVP) candidate of a current block from a first neighboring block group including a lower left neighboring block and a left neighboring block;
deriving, by the decoding apparatus, a second MVP candidate of the current block from a second neighboring block group including an upper right neighboring block, an upper neighboring block, and an upper left neighboring block;
selecting, by the decoding apparatus, an MVP of the current block from an MVP candidate list constructed based on the first MVP candidate and the second MVP candidate;
determining, by the decoding apparatus, a motion vector of the current block based on the selected MVP;
generating, by the decoding apparatus, a prediction sample of the current block based on the determined motion vector;
reconstructing, by the decoding apparatus, a current picture based on the generated prediction sample; and
performing, by the decoding apparatus, a deblocking filtering process on the reconstructed current picture,
wherein the first MVP candidate is derived based on a motion vector of the lower left neighboring block or the left neighboring block which satisfy a first condition or a second condition,
wherein the second MVP candidate is derived based on a motion vector of the upper right neighboring block, the upper neighboring block, or the upper left neighboring block which satisfy the first condition or the second condition,
wherein the first condition is whether a block in the first neighboring block group or the second neighboring block group has a reference picture and a reference picture list identical to a reference picture and a reference picture list of the current block, and
wherein the second condition is whether a block in the first neighboring block group or the second neighboring block group has a reference picture identical to the reference picture of the current block and has a reference picture list different from the reference picture list of the current block.
2. The method of claim 1 , wherein the first MVP candidate is derived based on a first search order, wherein the first search order is determined as in order of the lower left neighboring block and the left neighboring block,
wherein the second MVP candidate is derived based on a second search order, wherein the second search order is determined as in order of the upper right neighboring block, the upper neighboring block and the upper left neighboring block.
3. The method of claim 2 , wherein in deriving the first MVP candidate, when the lower left neighboring block is determined as not satisfying the first condition and the second condition, whether the left neighboring block satisfy the first condition or the second condition is checked, and
wherein in deriving the second MVP candidate, when the upper right neighboring block is determined as not satisfying the first condition and the second condition, whether the upper neighboring block satisfy the first condition or the second condition is checked.
4. The method of claim 3 , wherein in deriving the second MVP candidate, when the upper neighboring block is determined as not satisfying the first condition and the second condition, whether the upper left neighboring block satisfy the first condition or the second condition is checked.
5. The method of claim 1 , wherein the first MVP candidate is derived based on a motion vector of the lower left neighboring block or the left neighboring block which satisfy the first condition, the second condition or a third condition;
wherein the second MVP candidate is derived based on a motion vector of the upper right neighboring block, the upper neighboring block, or the upper left neighboring block which satisfy the first condition, the second condition or the third condition,
wherein the third condition is whether a block in the first neighboring block group or the second neighboring block group has a reference picture different from the reference picture of the current block.
6. The method of claim 5 , wherein in deriving the first MVP candidate, when the lower left neighboring block and the left neighboring block are determined as not satisfying the first condition and the second condition, whether the lower left neighboring block satisfy the third condition is checked, and
wherein in deriving the second MVP candidate, when the upper right neighboring block, the upper neighboring block and the upper left neighboring block are determined as not satisfying the first condition and the second condition, whether the upper right neighboring block satisfy the third condition is checked.
7. The method of claim 6 , wherein scaling is carried out to the motion vector of the lower left neighboring block or the left neighboring block satisfying the third condition based on a distance between a current picture to which the current block belongs and a reference picture of the current block and a distance between the current picture and a reference picture of the lower left neighboring block or the left neighboring block satisfying the third condition.
8. A video decoding apparatus, comprising:
a predictor configured to derive a first motion vector predictor (MVP) candidate of a current block from a first neighboring block group including a lower left neighboring block and a left neighboring block, to derive a second MVP candidate of the current block from a second neighboring block group including an upper right neighboring block, an upper neighboring block, and an upper left neighboring block, to select an MVP of the current block based on the first MVP candidate and the second MVP candidate, to determine a motion vector of the current block based on the selected MVP, to generate a prediction sample of the current block based on the determined motion vector;
an adder configured to reconstruct a current picture based on the generated prediction sample; and
a filter configured to perform a deblocking filtering process on the reconstructed current picture,
wherein the first MVP candidate is derived based on a motion vector of the lower left neighboring block or the left neighboring block which satisfy a first condition or a second condition,
wherein the second MVP candidate is derived based on a motion vector of the upper right neighboring block, the upper neighboring block, or the upper left neighboring block which satisfy the first condition or the second condition,
wherein the first condition is whether a block in the first neighboring block group or the second neighboring block group has a reference picture and a reference picture list identical to a reference picture and a reference picture list of the current block, and
wherein the second condition is whether a block in the first neighboring block group or the second neighboring block group has a reference picture identical to the reference picture of the current block and has a reference picture list different from the reference picture list of the current block.
9. The apparatus of claim 8 , wherein the first MVP candidate is derived based on a first search order, wherein the first search order is determined as in order of the lower left neighboring block and the left neighboring block,
wherein the second MVP candidate is derived based on a second search order, wherein the second search order is determined as in order of the upper right neighboring block, the upper neighboring block and the upper left neighboring block.
10. The apparatus of claim 9 , wherein in deriving the first MVP candidate, when the lower left neighboring block is determined as not satisfying the first condition and the second condition, whether the left neighboring block satisfy the first condition or the second condition is checked, and
wherein in deriving the second MVP candidate, when the upper right neighboring block is determined as not satisfying the first condition and the second condition, whether the upper neighboring block satisfy the first condition or the second condition is checked.
11. The apparatus of claim 10 , wherein in deriving the second MVP candidate, when the upper neighboring block is determined as not satisfying the first condition and the second condition, whether the upper left neighboring block satisfy the first condition or the second condition is checked.
12. The apparatus of claim 8 , wherein the first MVP candidate is derived based on a motion vector of the lower left neighboring block or the left neighboring block which satisfy the first condition, the second condition or a third condition;
wherein the second MVP candidate is derived based on a motion vector of the upper right neighboring block, the upper neighboring block, or the upper left neighboring block which satisfy the first condition, the second condition or the third condition,
wherein the third condition is whether a block in the first neighboring block group or the second neighboring block group has a reference picture different from the reference picture of the current block.
13. The apparatus of claim 12 , wherein in deriving the first MVP candidate, when the lower left neighboring block and the left neighboring block are determined as not satisfying the first condition and the second condition, whether the lower left neighboring block satisfy the third condition is checked, and
wherein in deriving the second MVP candidate, when the upper right neighboring block, the upper neighboring block and the upper left neighboring block are determined as not satisfying the first condition and the second condition, whether the upper right neighboring block satisfy the third condition is checked.
14. The apparatus of claim 13 , wherein scaling is carried out to the motion vector of the lower left neighboring block or the left neighboring block satisfying the third condition based on a distance between a current picture to which the current block belongs and a reference picture of the current block and a distance between the current picture and a reference picture of the lower left neighboring block or the left neighboring block satisfying the third condition.