Encoding/decoding method for video signal and device therefor
Embodiments of the present invention provide a video signal processing method and device. Particularly, a method for decoding a video signal, may comprise the steps of: checking whether a transfer skip is applied to a current block; obtaining, from a video signal, a transform index for indicating a transform type set applied to the current block when the transform skip is not applied to the current block, wherein the transform type set includes transform types applied to the current block in horizontal and vertical directions; checking whether the transform type set includes DCT2; determining a region to which a primary transform is applied based on a checking result; and performing an inverse transform on the region to which the primary transform is applied in the horizontal and vertical directions using the transform types included in the transform type set.
1. An apparatus for decoding a video signal, comprising:
a memory configured to store the video signal; and
a processor coupled to the memory,
wherein the processor is configured to:
check whether a transform skip is applied to a current block;
obtain a transform index specifying which transform kernels are applied along horizontal and vertical directions of the current block based on that the transform skip is not applied to the current block;
determine a non-zero region based on the transform kernels specified by the transform index and a width and/or a height of the current block, wherein the transform kernels correspond to at least one of predefined transform types including DCT2, DST7 and DCT8;
perform an inverse transform on the non-zero region based on the transform kernels specified by the transform index to generate residual samples of the current block; and
generate reconstructed samples of the current block based on the residual samples.
2. The apparatus of claim 1 , wherein, based on that the transform kernels correspond to DCT2, a width of the non-zero region is determined as a smaller value between the width of the current block and 32, and a height of the non-zero region is determined as a smaller value between the height of the current block and 32.
3. The apparatus of claim 1 , wherein, based on that the transform kernels correspond to one of a plurality of transform combinations of DST7 and/or DCT8, a width of the non-zero region is determined as a smaller value between the width of the current block and 16 and a height of the non-zero region is determined as a smaller value between the height of the current block and 16.
4. The apparatus of claim 1 , wherein the processor is further configured to obtain a syntax element indicating a position of a last significant coefficient in scan order within the current block,
wherein the processor is configured to obtain coefficients to which the inverse transform is applied from the video signal based on the position of the last significant coefficient.
5. The apparatus of claim 4 , wherein the syntax element is binarized according to a truncated unary method, and a maximum length of code for the syntax element is determined based on a remaining region other than the non-zero region.
6. An apparatus for encoding a video signal, comprising:
a memory configured to store the video signal; and
a processor coupled to the memory,
wherein the processor is configured to:
determine whether a transform skip is applied to a current block;
derive transform kernels being applied to a current block, wherein the transform kernels include a horizontal transform kernel and a vertical transform kernel;
determine a non-zero region in which a transform is applied to the current block based on the transform kernels and a width and/or a height of the current block; and
perform a transform on the current block based on the transform kernels;
generate a transform index specifying which transform kernels are applied along horizontal and vertical directions of the current block based on that the transform skip is not applied to the current block, wherein the transform kernels correspond to at least one of predefined transform types including DCT2, DST7 and DCT8; and
generate a syntax element representing whether the transform skip is applied to the current block.
7. The apparatus of claim 6 , wherein, based on that the transform kernels correspond to DCT2, a width of the non-zero region is determined as a smaller value between the width of the current block and 32, and a height of the non-zero region is determined as a smaller value between the height of the current block and 32.
8. The apparatus of claim 6 , wherein, based on that the transform kernels correspond to one of a plurality of transform combinations of DST7 and/or DCT8, a width of the non-zero region is determined as a smaller value between the width of the current block and 16 and a height of the non-zero region is determined as a smaller value between the height of the current block and 16.
9. The apparatus of claim 6 , wherein the processor is further configured to generate a syntax element indicating a position of a last significant coefficient in scan order within the current block.
10. The apparatus of claim 9 , wherein the syntax element is binarized according to a truncated unary method, and a maximum length of code for the syntax element is determined based on a remaining region other than the non-zero region.
11. An apparatus configured to transmit data for a video signal, comprising:
at least one processor configured to obtain a bitstream for the video signal; and
a transmitter configured to transmit the data comprising the bitstream,
wherein the at least one processor is configured to:
determine whether a transform skip is applied to a current block;
derive transform kernels being applied to a current block, wherein the transform kernels include a horizontal transform kernel and a vertical transform kernel;
determine a non-zero region in which a transform is applied to the current block based on the transform kernels and a width and/or a height of the current block; and
perform a transform on the current block based on the transform kernels;
generate a transform index indicating which transform kernels are applied along horizontal and vertical directions of the current block based on that the transform skip is not applied to the current block, wherein the transform kernels correspond to at least one of predefined transform types including DCT2, DST7 and DCT8; and
generate a syntax element representing whether the transform skip is applied to the current block.