Device and method for encoding and decoding motion information by means of neighboring motion information
A method, performed by a decoding apparatus, of decoding motion information, including: obtaining change information indicating whether to change motion information of a neighboring block of a current block; based on the change information indicating to change the motion information, determining a prediction direction of the current block by changing a prediction direction of the neighboring block; based on the prediction direction of the neighboring block being a first uni-direction and the prediction direction of the current block being a second uni-direction or a bi-direction, selecting a reference picture of the second uni-direction of the current block from a second reference picture list; obtaining a motion vector of the second uni-direction of the current block; and reconstructing the current block using a reference block indicated by the motion vector of the second uni-direction of the current block.
1 . A method, performed by a decoding apparatus, of decoding motion information, the method comprising:
obtaining, from a bitstream, information indicating whether to change motion information of a neighboring block to determine motion information of a current block,
wherein the information represents index information indicating one of a first value, a second value or a third value, and
wherein, when the information indicates the first value, it is determined not to change the motion information of the neighboring block, and when the information indicates the second value or the third value, it is determined to change the motion information of the neighboring block;
when the information indicates the change of the motion information of the neighboring block, a slice comprising the current block is a bi-predictive slice, and a prediction direction of the neighboring block is a list 0 direction, determining a prediction direction of the current block as a list 1 direction or bi-direction according to a value of the information;
selecting a reference picture of the current block from a reference picture list 1 based on whether a picture order count (POC) difference between a current picture comprising the current block and a reference picture of the neighboring block included in a reference picture list 0 is identical to a POC difference between the current picture and a reference picture having a first index in the reference picture list 1 ,
wherein when the POC difference between the current picture and the reference picture of the neighboring block is identical to the POC difference between the current picture and the reference picture having the first index in the reference picture list 1 , the reference picture having the first index in the reference picture list 1 is selected as the reference picture of the current block, and
wherein when the POC difference between the current picture and the reference picture of the neighboring block is not identical to the POC difference between the current picture and the reference picture having the first index in the reference picture list 1 , a reference picture having a second index in the reference picture list 1 is selected as the reference picture of the current block;
obtaining a motion vector of the current block by using a motion vector of the neighboring block and a differential motion vector of the current block; and
reconstructing the current block by using the reference picture of the current block and the motion vector of the current block,
wherein when the information indicates the change of the motion information of the neighboring block, and the slice comprising the current block is not the bi-predictive slice, the motion vector of the current block is obtained by applying an offset to the motion vector of the neighboring block.
2 . An apparatus of decoding motion information, the apparatus comprising:
a bitstream obtainer configured to obtain, from a bitstream, information indicating whether to change motion information of a neighboring block to determine motion information of a current block,
wherein the information represents index information indicating one of a first value, a second value or a third value, and
wherein, when the information indicates the first value, it is determined not to change the motion information of the neighboring block, and when the information indicates the second value or the third value, it is determined to change the motion information of the neighboring block;
a motion information obtainer configured to, when the information indicates the change of the motion information of the neighboring block, a slice comprising the current block is a bi-predictive slice, and a prediction direction of the neighboring block is a list 0 direction, determine a prediction direction of the current block as a list 1 direction or bi-direction according to a value of the information, select a reference picture of the current block from a reference picture list 1 based on whether a picture order count (POC) difference between a current picture comprising the current block and a reference picture of the neighboring block included in a reference picture list 0 is identical to a POC difference between the current picture and a reference picture having a first index in the reference picture list 1 , wherein when the POC difference between the current picture and the reference picture of the neighboring block is identical to the POC difference between the current picture and the reference picture having the first index in the reference picture list 1 , the reference picture having the first index in the reference picture list 1 is selected as the reference picture of the current block, and wherein when the POC difference between the current picture and the reference picture of the neighboring block is not identical to the POC difference between the current picture and the reference picture having the first index in the reference picture list 1 , a reference picture having a second index in the reference picture list 1 is selected as the reference picture of the current block, and obtain a motion vector of the current block by using a motion vector of the neighboring block and a differential motion vector of the current block; and
a prediction decoder configured to reconstruct the current block by using the reference picture of the current block and the motion vector of the current block,
wherein when the information indicates the change of the motion information of the neighboring block, and the slice comprising the current block is not the bi-predictive slice, the motion vector of the current block is obtained by applying an offset to the motion vector of the neighboring block.
3 . A method, performed by an encoding apparatus, of encoding motion information, the method comprising:
determining whether to change motion information of a neighboring block to determine motion information of a current block;
when it is determined to change the motion information of the neighboring block, a slice comprising the current block is a bi-predictive slice, and a prediction direction of the neighboring block is a list 0 direction, determining a prediction direction of the current block as a list 1 direction or bi-direction;
selecting a reference picture of the current block from a reference picture list 1 based on whether a picture order count (POC) difference between a current picture comprising the current block and a reference picture of the neighboring block included in a reference picture list 0 is identical to a POC difference between the current picture and a reference picture having a first index in the reference picture list 1 ,
wherein when the POC difference between the current picture and the reference picture of the neighboring block is identical to the POC difference between the current picture and the reference picture having the first index in the reference picture list 1 , the reference picture having the first index in the reference picture list 1 is selected as the reference picture of the current block, and
wherein when the POC difference between the current picture and the reference picture of the neighboring block is not identical to the POC difference between the current picture and the reference picture having the first index in the reference picture list 1 , a reference picture having a second index in the reference picture list 1 is selected as the reference picture of the current block;
determining a motion vector of the current block by using a motion vector of the neighboring block;
encoding the current block by using the reference picture of the current block and the motion vector of the current block; and
generating a bitstream comprising information indicating whether to change the motion information of the neighboring block,
wherein a differential motion vector of the current block is obtained by using the motion vector of the current block and the motion vector of the neighboring block,
wherein the information represents index information indicating one of a first value, a second value or a third value,
wherein, when it is determined not to change the motion information of the neighboring block, the information indicates the first value, and when it is determined to change the motion information of the neighboring block, the information indicates the second value or the third value,
wherein the determined prediction direction of the current block is indicated by the information, and
wherein when it is determined to change the motion information of the neighboring block, and the slice comprising the current block is not the bi-predictive slice, the motion vector of the current block is obtained by applying an offset to the motion vector of the neighboring block.
4 . A non-transitory computer-readable medium for recording a bitstream, the bitstream comprising:
information indicating whether to change motion information of a neighboring block to determine motion information of a current block,
wherein when the information indicates the change of the motion information of the neighboring block, a slice comprising the current block is a bi-predictive slice, and a prediction direction of the neighboring block is a list 0 direction, a prediction direction of current block is determined as a list 1 direction or bi-direction,
wherein a reference picture of the current block is selected from a reference picture list 1 based on whether a picture order count (POC) difference between a current picture comprising the current block and a reference picture of the neighboring block included in a reference picture list 0 is identical to a POC difference between the current picture and a reference picture having a first index in the reference picture list 1 ,
wherein when the POC difference between the current picture and the reference picture of the neighboring block is identical to the POC difference between the current picture and the reference picture having the first index in the reference picture list 1 , the reference picture having the first index in the reference picture list 1 is selected as the reference picture of the current block, and
wherein when the POC difference between the current picture and the reference picture of the neighboring block is not identical to the POC difference between the current picture and the reference picture having the first index in the reference picture list 1 , a reference picture having a second index in the reference picture list 1 is selected as the reference picture of the current block,
wherein a motion vector of the current block is determined by using a motion vector of the neighboring block,
wherein the current block is encoded by using the reference picture of the current block and the motion vector of the current block,
wherein a differential motion vector of the current block is obtained by using the motion vector of the current block and the motion vector of the neighboring block,
wherein the information represents index information indicating one of a first value, a second value or a third value,
wherein, when it is determined not to change the motion information of the neighboring block, the information indicates the first value, and when it is determined to change the motion information of the neighboring block, the information indicates the second value or the third value,
wherein the determined prediction direction of the current block is indicated by the information, and
wherein when the information indicates the change of the motion information of the neighboring block, and the slice comprising the current block is not the bi-predictive slice, the motion vector of the current block is obtained by applying an offset to the motion vector of the neighboring block.