Method and device for encoding/decoding motion vector

1. A motion vector encoding apparatus comprising:

a predictor configured to obtain motion vector predictor candidates by using at least one of a spatial candidate block and a temporal candidate block of a current block, and to determine motion vector predictor of the current block among the motion vector predictor candidates, a motion vector of the current block, and a motion vector resolution of the current block; and

an encoder configured to encode information representing the motion vector predictor of the current block, a residual motion vector between the motion vector of the current block and the motion vector predictor of the current block, and information representing the motion vector resolution of the current block,

wherein the encoder adaptively down-scales the residual motion vector based on the motion vector resolution of the current block and a minimum motion vector resolution to encode the residual motion vector.

2. The motion vector encoding apparatus of claim 1 , wherein the plurality of predetermined motion vector resolutions include a resolution of a pixel unit that is greater than a resolution of one-pel unit.

3. The motion vector encoding apparatus of claim 1 , wherein the predictor performs searching in a reference block in pixel units of a first motion vector resolution by using a set of first motion vector candidates including one or more motion vector predictor candidates selected from the motion vector predictor candidates, and

performs searching in the reference block in pixel units of a second motion vector resolution by using a set of second motion vector candidates including one or more motion vector predictor candidates selected from the motion vector predictor candidates,

wherein the first motion vector resolution and the second motion vector resolution are different from each other, and

the set of the first motion vector predictor candidates and the set of the second motion vector predictor candidates are obtained from candidate blocks that are different from each other from among candidate blocks included in the spatial candidate block and the temporal candidate block.

4. The motion vector encoding apparatus of claim 1 , wherein the predictor performs searching in a reference block in pixel units of a first motion vector resolution by using a set of first motion vector candidates including one or more motion vector predictor candidates selected from the motion vector predictor candidates, and

performs searching in the reference block in pixel units of a second motion vector resolution by using a set of second motion vector candidates including one or more motion vector predictor candidates selected from the motion vector predictor candidates,

wherein the first motion vector resolution and the second motion vector resolution are different from each other, and

the set of the first motion vector predictor candidates and the set of the second motion vector predictor candidates include different numbers of motion vector predictors from each other.

5. The motion vector encoding apparatus of claim 1 , wherein, when a pixel unit of the motion vector resolution of the current block is greater than a pixel unit of the minimum motion vector resolution, the encoder down-scales the residual motion vector according to the motion vector resolution of the current block to encode the residual motion vector.

6. The motion vector encoding apparatus of claim 1 , wherein, when the current block is a current block coding unit of an image, a motion vector resolution is equally determined with respect to each coding unit, and there is a prediction unit that is predicted in an advanced motion vector prediction (AMVP) mode in the current coding unit, the encoder encodes the information indicating a motion vector resolution of the prediction unit predicted in the AMVP mode as information representing the motion vector resolution of the current block.

7. The motion vector encoding apparatus of claim 1 , wherein, when the current block is a current block coding unit of an image, a motion vector resolution is equally determined with respect to each prediction unit, and there is a prediction unit that is predicted in an advanced motion vector prediction (AMVP) mode in the current coding unit, the encoder encodes information representing a motion vector resolution for each prediction unit predicted in the AMVP mode in the current block, as information representing the motion vector resolution of the current block.

8. A motion vector decoding apparatus comprising:

an obtainer configured to obtain motion vector predictor candidates by using at least one of a spatial candidate block and a temporal candidate block of a current block, to obtain information representing motion vector predictor of the current block from among the motion vector predictor candidates, and to obtain a residual motion vector between a motion vector of the current block and the motion vector predictor of the current block, and information representing a motion vector resolution of the current block; and

a decoder configured to reconstruct the motion vector of the current block based on the residual motion vector, the information representing the motion vector predictor of the current block, and the information representing the motion vector resolution of the current block,

wherein the decoder adaptively up-scales the residual motion vector based on the motion vector resolution of the current block and a minimum motion vector resolution to reconstruct the residual motion vector.

9. The motion vector decoding apparatus of claim 8 , wherein the plurality of predetermined motion vector resolutions include a resolution of a pixel unit that is greater than a resolution of one-pel unit.

10. The motion vector decoding apparatus of claim 8 , wherein the motion vector predictor candidates of the plurality of predetermined motion vector resolutions comprise a set of first motion vector predictor candidates including one or more motion vector predictor candidates of a first motion vector resolution and a set of second motion vector predictor candidates including one or more motion vector predictor candidates of a second motion vector resolution,

wherein the first motion vector resolution and the second motion vector resolution are different from each other, and

the set of the first motion vector predictor candidates and the set of the second motion vector predictor candidates are obtained from candidate blocks that are different from each other from among candidate blocks included in the spatial candidate block and the temporal candidate block.

11. The motion vector decoding apparatus of claim 8 , wherein the motion vector predictor candidates of the plurality of predetermined motion vector resolutions comprise a set of first motion vector predictor candidates including one or more motion vector predictor candidates of a first motion vector resolution and a set of second motion vector predictor candidates including one or more motion vector predictor candidates of a second motion vector resolution,

wherein the first motion vector resolution and the second motion vector resolution are different from each other, and

the set of the first motion vector predictor candidates include different numbers of motion vector predictor candidates from each other.

12. The motion vector decoding apparatus of claim 8 , wherein, when a pixel unit of the motion vector resolution of the current block is greater than a pixel unit of the minimum motion vector resolution, the decoder up-scales the residual motion vector according to the motion vector resolution of the current block to reconstruct the residual motion vector.

13. The motion vector decoding apparatus of claim 8 , wherein, when the current block is a current block coding unit of an image, a motion vector resolution is equally determined with respect to each coding unit, and there is a prediction unit that is predicted in an advanced motion vector prediction (AMVP) mode in the current coding unit, the obtainer obtains information representing the motion vector resolution of the prediction unit predicted in the AMVP mode, as information representing the motion vector resolution of the current block, from a bitstream.

14. A method for decoding a motion vector, the method comprising:

obtaining motion vector predictor candidates by using at least one of a spatial candidate block and a temporal candidate block of a current block;

obtaining information representing motion vector predictor of the current block from among the motion vector predictor candidates;

obtaining a residual motion vector between a motion vector of the current block and the motion vector predictor of the current block, and information representing a motion vector resolution of the current block; and

reconstructing the motion vector of the current block based on the residual motion vector, the information representing the motion vector predictor of the current block, and the information representing the motion vector resolution of the current block,

wherein the reconstructing of the motion vector of the current block comprises adaptively up-scaling the residual motion vector based on the motion vector resolution of the current block and a minimum motion vector resolution to reconstruct the residual motion vector.

15. The method of claim 14 , wherein the plurality of predetermined motion vector resolutions include a resolution of a pixel unit that is greater than a resolution of one-pel unit.

16. The method of claim 14 , wherein the motion vector predictor candidates of the plurality of predetermined motion vector resolutions comprise a set of first motion vector predictor candidates including one or more motion vector predictor candidates of a first motion vector resolution and a set of second motion vector predictor candidates including one or more motion vector predictor candidates of a second motion vector resolution,

wherein the first motion vector resolution and the second motion vector resolution are different from each other, and

the set of the first motion vector predictor candidates and the set of the second motion vector predictor candidates are obtained from candidate blocks that are different from each other from among candidate blocks included in the spatial candidate block and the temporal candidate block.

17. The method of claim 14 , wherein the motion vector predictor candidates of the plurality of predetermined motion vector resolutions comprise a set of first motion vector predictor candidates including one or more motion vector predictor candidates of a first motion vector resolution and a set of second motion vector predictor candidates including one or more motion vector predictor candidates of a second motion vector resolution,

wherein the first motion vector resolution and the second motion vector resolution are different from each other, and

the set of the first motion vector predictor candidates include different numbers of motion vector predictor candidates from each other.

18. The method of claim 14 , wherein the reconstructing the motion vector of the current block based on the residual motion vector, the information representing the motion vector predictor of the current block, and motion vector resolution information of the current block comprises,

when a pixel unit of the motion vector resolution of the current block is greater than a pixel unit of the minimum motion vector resolution, up-scaling the residual motion vector according to the motion vector resolution of the current block to reconstruct the residual motion vector.

19. The method of claim 14 , wherein the obtaining the residual motion vector between the motion vector of the current block and the motion vector predictor of the current block and information representing the motion vector resolution of the current block comprises,

when the current block is a current block coding unit of an image, a motion vector resolution is equally determined with respect to each coding unit, and there is a prediction unit that is predicted in an advanced motion vector prediction (AMVP) mode in the current coding unit, obtaining information representing the motion vector resolution of the prediction unit predicted in the AMVP mode, as information representing the motion vector resolution of the current block, from a bitstream.

20. A non-transitory computer-readable recording medium having recorded thereon a program for performing the method of claim 14 .