Method and device for encoding/decoding residual block on basis of quantization parameter
An encoding/decoding device according to the present invention derives a residual coefficient of a residual block from a bitstream, calculates a quantization parameter for the residual block, performs inverse quantization on the residual coefficient by using the quantization parameter, and performs inverse conversion on the inversely quantized residual coefficient, thereby enabling restoration of a residual sample of the residual block.
1. A method of decoding a video, comprising:
deriving a residual coefficient of a residual block from a bitstream;
calculating a quantization parameter for the residual block;
performing an inverse-quantization on the residual coefficient using the calculated quantization parameter; and
reconstructing a residual sample of the residual block by performing an inverse-transform on the inverse-quantized residual coefficient,
wherein a quantization parameter for a chroma component block of the residual block is derived based on a quantization parameter prediction value for the chroma component block and a quantization parameter offset,
wherein the quantization parameter offset includes a first quantization parameter offset signaled at a picture level,
wherein the quantization parameter prediction value for the chroma component block is derived based on a quantization parameter for a luma component block of the residual block, and
wherein when the chroma component block has a partition structure independent of the luma component block, the quantization parameter prediction value for the chroma component block is derived based on a quantization parameter of one of a plurality of luma component blocks corresponding to the chroma component block.
2. The method of claim 1 , wherein the residual block is determined by a block division based on at least one of a quad tree, a binary tree, or a triple tree.
3. The method of claim 1 , wherein the quantization parameter offset further includes a second quantization parameter offset signaled at a block level.
4. The method of claim 1 , wherein the quantization parameter for the luma component block is derived based on at least one of a quantization parameter prediction value or a quantization parameter difference value for the luma component block.
5. The method of claim 1 , wherein the quantization parameter of the one of the plurality of luma component blocks is representative of a quantization parameter of a luma component block corresponding to a position of a center sample.
6. A method of encoding a video, comprising:
performing a transform on a residual sample of a residual block to obtain a transform coefficient of the residual block;
performing a quantization on the transform coefficient of the residual block based on a quantization parameter to obtain a quantized transform coefficient of the residual block; and
generating a bitstream by encoding the quantized transform coefficient,
wherein a quantization parameter for a chroma component block of the residual block is derived based on a quantization parameter prediction value for the chroma component block and a quantization parameter offset,
wherein the quantization parameter offset includes a first quantization parameter offset signaled at a picture level,
wherein the quantization parameter prediction value for the chroma component block is derived based on a quantization parameter for a luma component block of the residual block, and
wherein when the chroma component block has a partition structure independent of the luma component block, the quantization parameter prediction value for the chroma component block is derived based on a quantization parameter of one of a plurality of luma component blocks corresponding to the chroma component block.
7. A non-transitory computer-readable medium for storing data associated with a video signal, comprising:
a data stream stored in the non-transitory computer-readable medium, the data stream including a residual coefficient of a residual block,
wherein the residual coefficient of the residual block is inverse-quantized based on a quantization parameter for an inverse-quantization of the residual block,
wherein the inverse-quantized residual coefficient is inverse-transformed to reconstruct a residual sample of the residual block,
wherein a quantization parameter for a chroma component block of the residual block is derived based on a quantization parameter prediction value for the chroma component block and a quantization parameter offset,
wherein the data stream includes the quantization parameter offset including a first quantization parameter offset encoded at a picture level,
wherein the quantization parameter prediction value for the chroma component block is derived based on a quantization parameter for a luma component block of the residual block, and
wherein when the chroma component block has a partition structure independent of the luma component block, the quantization parameter prediction value for the chroma component block is derived based on a quantization parameter of one of a plurality of luma component blocks corresponding to the chroma component block.