Method for encoding/decoding image signal, and device therefor
An image decoding method according to the present invention comprises the steps of: referring to a first flag for indicating whether intra block-based delta pulse code modulation (BDPCM) signaled through a sequence parameter set is permitted, so as to determine whether a second flag for indicating whether the intra BDPCM is applied to a current block is parsed; determining whether the intra BDPCM is applied to the current block on the basis of the second flag; determining an intra BDPCM mode of the current block when it is determined that the intra BDPCM is applied to the current block; and acquiring a residual sample of the current block on the basis of the intra BDPCM mode.
1. A video decoding method comprising:
parsing a first flag signaled by a sequence parameter set, the first flag representing whether an intra BDPCM (Block-based Delta Pulse Code Modulation) is available in performing intra-prediction with respect to a picture,
wherein a value of the first flag is selected from among:
a first value indicating that the intra BDPCM may be used in performing intra-prediction with respect to the picture, and
a second value indicating that the intra BDPCM may not be used in performing intra-prediction with respect to the picture;
determining, based on the first flag, whether to parse a second flag representing whether intra BDPCM is applied to a current block of the picture,
wherein determining whether to parse the second flag comprises:
determining that the value of the first flag is the first value, and
responsive to determining that the value of the first flag is the first value, parsing the second flag, and
wherein a value of the second flag is selected from among:
a third value indicating that the intra BDPCM is applied to the current block, and
a fourth value indicating that the intra BDPCM is not applied to the current block;
determining whether the intra BDPCM is applied to the current block based on the second flag;
responsive to determining that the intra BDPCM is applied to the current block, determining an intra BDPCM mode of the current block; and
obtaining a residual sample of the current block based on the intra BDPCM mode.
2. The method of claim 1 , wherein the intra BDPCM mode is determined to be a horizontal direction or a vertical direction.
3. The method of claim 2 , wherein the residual sample is derived by adding a neighboring residual sample adjacent to the residual sample and a residual difference value decoded from a bitstream.
4. The method of claim 1 , wherein when the intra BDPCM is applied to the current block, a transform skip is applied to the current block.
5. The method of claim 1 , wherein when the intra BDPCM is applied to the current block, an intra prediction mode of the current block is inferred to have a horizontal direction or a vertical direction when deriving an MPM (Most Probable Mode) candidate for a neighboring block adjacent to a right or a bottom of the current block.
6. A video encoding method comprising:
determining whether intra BDPCM (Block-based Delta Pulse Code Modulation) is applied to a current block of a picture;
determining an intra BDPCM mode of the current block when it is determined to apply the intra BDPCM to the current block;
obtaining a residual sample of the current block based on the intra BDPCM mode; and
encoding information representing whether to apply the intra BDPCM based on whether the intra BDPCM has been applied to the current block;
wherein the information includes:
a first flag included in a sequence parameter set, the first flag representing whether the intra BDPCM is available in performing intra-prediction with respect to a picture,
wherein a value of the first flag is selected from among:
a first value indicating that the intra BDPCM may be used in performing intra-prediction with respect to the picture, and
a second value indicating that the intra BDPCM may not be used in performing intra-prediction with respect to the picture, and
a second flag that is selectively parsed based on a value of the first flag,
wherein determining whether to parse the second flag comprises:
determining that the value of the first flag is the first value, and
responsive to determining that the value of the first flag is the first value, parsing the second flag, and
wherein a value of the second flag is selected from among:
a third value indicating that the intra BDPCM is applied to the current block, and
a fourth value indicating that the intra BDPCM is not applied to the current block.
7. The method of claim 6 , wherein the intra BDPCM mode is determined as a horizontal direction or a vertical direction.
8. The method of claim 7 , wherein a residual coefficient of the residual sample is derived by subtracting the residual sample from a neighboring residual sample adjacent to the residual sample.
9. The method of claim 6 , wherein when the intra BDPCM is applied to the current block, a transform skip is applied to the current block.
10. The method of claim 6 , wherein when the intra BDPCM is applied to the current block, an intra prediction mode of the current block is inferred to have a horizontal direction or a vertical direction when deriving an MPM (Most Probable Mode) candidate of a neighboring block adjacent to a right or a bottom of the current block.