Video encoding device and video decoding device using high-precision skip encoding and method thereof
Provided is a video decoding method performed by a video decoding apparatus, the video decoding method including: determining prediction mode information of a current block and an index indicating a prediction candidate, from a bitstream; determining a prediction candidate list according to the prediction mode information; when the prediction mode information of the current block indicates a pre-set prediction mode, determining a motion vector indicated by the index indicating the prediction candidate from the prediction candidate list, and determining a prediction motion vector of the current block based on at least one of pieces of motion prediction information related to the motion vector; and determining a motion vector of the current block based on the prediction motion vector, wherein the pre-set prediction mode is a prediction mode different from a skip mode and a merge mode.
1 . A video decoding method performed by a video decoding apparatus, the video decoding method comprising:
obtaining, from a bitstream, a skip mode flag indicating whether a current block is predicted in a skip mode;
in response to the skip mode flag indicating that the current block is not predicted in the skip mode, obtaining a merge mode flag for a the current block from athe bitstream;
in response to determining whether the merge mode flag indicates that the current block is predicted in a merge mode or not, obtaining motion vector prediction mode information of the current block, from the bitstream;
when the motion vector prediction mode information of the current block indicates a pre-set prediction mode, obtaining, from the bitstream, information indicating a signed direction of a motion vector difference, information indicating a pixel distance of the motion vector difference, and a first index indicating a first motion vector candidate from a first candidate list, wherein the first candidate list including motion vectors of blocks adjacent to the current block, determining the first motion vector candidate indicated by the first index from the first candidate list, determining the motion vector difference based on the signed direction of the motion vector difference and the pixel distance of the motion vector difference, and determining a motion vector of the current block based on the first motion vector candidate and the motion vector difference;
when the motion vector prediction mode information of the current block does not indicate the pre-set prediction mode, obtaining, from the bitstream, a second index indicating a second motion vector candidate from a second candidate list, determining the second motion vector candidate indicated by the second index from the second candidate list, and determining the motion vector of the current block based on the second motion vector candidate;
obtaining a residual block of the current block by performing inverse transformation on transformation coefficients of the current block; and
determining a reconstructed block of the current block by using the residual block and a prediction block indicated by the motion vector,
wherein the signed direction is one of a horizontal component of a positive sign, a horizontal component of a negative sign, a vertical component of the positive sign and a vertical component of the negative sign, and the pixel distance comprises a sub-pel unit and an integer-pel unit.
2 . A video encoding method performed by a video encoding apparatus, the video encoding method comprising:
generating a skip mode flag indicating whether a current block is predicted in a skip mode,
when the current block is not predicted in the skip mode, generating a merge mode flag for the current block to indicate whether the current block is predicted in a merge mode or not;
based on whether the current block is predicted in the merge mode or not, generating motion vector prediction mode information of the current block indicating whether the current block is predicted in a pre-set prediction mode;
when the current block is predicted in the pre-set prediction mode, determining a motion vector of the current block, determining a first candidate list including motion vectors of blocks adjacent to the current block, determining a first motion vector candidate from the first candidate list, determining a motion vector difference between the first motion vector candidate and the motion vector of the current block, and generating information indicating a signed direction of the motion vector difference, information indicating a pixel distance of the motion vector difference, and a first index indicating the first motion vector candidate from the first candidate list;
when the current block is not predicted in the pre-set prediction mode, determining the motion vector of the current block, determining a second candidate list including the motion vectors of blocks adjacent to the current block, determine a second motion vector candidate from the second candidate list, and generating a second index indicating the second motion vector candidate from the second candidate list;
obtaining a residual block of the current block between the current block and a prediction block corresponding to the motion vector of the current block; and
generating transform coefficients of the residual block by performing transformation on the residual block of the current block,
wherein the signed direction is one of a horizontal component of a positive sign, a horizontal component of a negative sign, a vertical component of the positive sign and a vertical component of the negative sign, and the pixel distance comprises a sub-pel unit and an integer-pel unit.
3 . A method of transmitting a bitstream generated by a video encoding apparatus, the method comprising:
generating a skip mode flag indicating whether a current block is predicted in a skip mode,
when the current block is not predicted in the skip mode, generating a merge mode flag for the current block to indicate whether the current block is predicted in a merge mode or not;
based on whether the current block is predicted in the merge mode or not, generating motion vector prediction mode information of the current block indicating whether the current block is predicted in a pre-set prediction mode;
when the current block is predicted in the pre-set prediction mode, determining a motion vector of the current block, determining a first candidate list including motion vectors of blocks adjacent to the current block, determining a first motion vector candidate from the first candidate list, determining a motion vector difference between the first motion vector candidate and the motion vector of the current block, and generating information indicating a signed direction of the motion vector difference, information indicating a pixel distance of the motion vector difference, and a first index indicating the first motion vector candidate from the first candidate list;
when the current block is not predicted in the pre-set prediction mode, determining the motion vector of the current block, determining a second candidate list including the motion vectors of blocks adjacent to the current block, determine a second motion vector candidate from the second candidate list, and generating a second index indicating the second motion vector candidate from the second candidate list;
obtaining a residual block of the current block between the current block and a prediction block corresponding to the motion vector of the current block;
encoding transform coefficients of the residual block, the transform coefficients generated by performing transformation on the residual block of the current block; and
outputting the bitstream including the skip mode flag, the merge mode flag, the motion vector prediction mode information and the encoded transform coefficients,
wherein the signed direction is one of a horizontal component of a positive sign, a horizontal component of a negative sign, a vertical component of the positive sign and a vertical component of the negative sign, and the pixel distance comprises a sub-pel unit and an integer-pel unit.