Method and device for processing video signal using multiple transform kernels

A video signal encoding device comprising a processor,

• wherein the processor is configured to:
• obtain a bitstream to be decoded by a decoder using a decoding method, the decoding method comprising:
• splitting a current block into a plurality of transform blocks,
• wherein an intra sub-partitions (ISP) mode is applied to the current block;
• determining a horizontal transform kernel applied to a current transform block among the plurality of transform blocks;
• determining a vertical transform kernel applied to the current transform block;
• and
• reconstructing the current block based on at least one of the horizontal transform kernel and/or the vertical transform kernel,
• wherein when a width of the current transform block is less than a first threshold or greater than a second threshold, the horizontal transform kernel is determined to be a transform kernel based on a discrete cosine transform type-2 (DCT-2),
• wherein when the width of the current transform block is greater than or equal to the first threshold and less than or equal to the second threshold, the horizontal transform kernel is determined to be a transform kernel based on a discrete sine transform type-7 (DST-7),
• wherein when a height of the current transform block is less than the first threshold or greater than the second threshold, the vertical transform kernel is determined to be the transform kernel based on the DCT-2, and
• wherein when the height of the current transform block is greater than or equal to the first threshold and less than or equal to the second threshold, the vertical transform kernel is determined to be the transform kernel based on the DST-7.

A method for obtaining a bitstream, the method comprising:

• splitting a current block into a plurality of transform blocks,
• wherein an intra sub-partitions (ISP) mode is applied to the current block;
• determining a horizontal transform kernel applied to a current transform block among the plurality of transform blocks;
• determining a vertical transform kernel applied to the current transform block;
• and
• obtaining the bitstream including information related to splitting the current block,
• wherein when a width of the current transform block is less than a first threshold or greater than a second threshold, the horizontal transform kernel is determined to be a transform kernel based on a discrete cosine transform type-2 (DCT-2),
• wherein when the width of the current transform block is greater than or equal to the first threshold and less than or equal to the second threshold, the horizontal transform kernel is determined to be a transform kernel based on a discrete sine transform type-7 (DST-7),
• wherein when a height of the current transform block is less than the first threshold or greater than the second threshold, the vertical transform kernel is determined to be the transform kernel based on the DCT-2, and
• wherein when the height of the current transform block is greater than or equal to the first threshold and less than or equal to the second threshold, the vertical transform kernel is determined to be the transform kernel based on the DST-7.

A video signal processing method, the method comprising:

• splitting a current block into a plurality of transform blocks,
• wherein an intra sub-partitions (ISP) mode is applied to the current block;
• determining a horizontal transform kernel applied to a current transform block among the plurality of transform blocks;
• determining a vertical transform kernel applied to the current transform block;
• and
• reconstructing the current block based on at least one of the horizontal transform kernel and/or the vertical transform kernel,
• wherein when a width of the current transform block is less than a first threshold or greater than a second threshold, the horizontal transform kernel is determined to be a transform kernel based on a discrete cosine transform type-2 (DCT-2),
• wherein when the width of the current transform block is greater than or equal to the first threshold and less than or equal to the second threshold, the horizontal transform kernel is determined to be a transform kernel based on a discrete sine transform type-7 (DST-7),
• wherein when a height of the current transform block is less than the first threshold or greater than the second threshold, the vertical transform kernel is determined to be the transform kernel based on the DCT-2, and
• wherein when the height of the current transform block is greater than or equal to the first threshold and less than or equal to the second threshold, the vertical transform kernel is determined to be the transform kernel based on the DST-7.