Video coding method on basis of secondary transform, and device therefor

    公开(公告)号:US12058374B2

    公开(公告)日:2024-08-06

    申请号:US17962077

    申请日:2022-10-07

    CPC classification number: H04N19/61 H04N19/132 H04N19/159 H04N19/176 H04N19/18

    Abstract: A video transform method includes: receiving a quantized transform coefficient for a target block and a transform index for a non-separated secondary transform; inverse-quantizing the quantized transform coefficient; deriving an input transform coefficient size indicating the length of the inverse-quantized transform coefficient to which the non-separated secondary transform has been applied, an output transform coefficient size indicating the length of a modified transform coefficient to which the non-separated secondary transform has been applied, and a transform set mapped to the intra mode of the target block, when the transform index does not indicate that the non-separated secondary transform is not performed; and deriving the modified transform coefficient on the basis of a matrix operation on a transform kernel matrix in the transform set indicated by the transform index, and a transform coefficient list corresponding to the input transform coefficient size.

    DMVR-based inter-prediction method and device

    公开(公告)号:US11917160B2

    公开(公告)日:2024-02-27

    申请号:US17577671

    申请日:2022-01-18

    Abstract: An image decoding method performed by a decoding device according to the present document comprises the steps of: deriving a motion vector for a current block; determining whether to apply refinement to the motion vector for the current block; deriving a refined motion vector by applying decoder-side motion vector refinement (DMVR) to the motion vector if it is determined to apply refinement to the motion vector for the current block; deriving prediction samples for the current block on the basis of the refined motion vector; and generating reconstruction samples for the current block on the basis of the prediction samples, wherein the step of determining whether to apply refinement includes determining whether to apply the refinement on the basis of at least one of the size of the current block and bi-prediction weight index information for the current block.

    Inter-prediction method and apparatus in image coding system

    公开(公告)号:US11800114B2

    公开(公告)日:2023-10-24

    申请号:US17843531

    申请日:2022-06-17

    Abstract: An image decoding method performed by a decoding apparatus includes the operations of: deriving a correspondence block corresponding to the current block of the current picture, the correspondence block being located in a co-located picture; deriving a movement vector of the correspondence block; scaling the movement vector of the correspondence block based on a first temporal distance and second temporal distance, the first temporal distance being the difference between the POC values of the co-located picture and POC values of the reference picture of the correspondence block, and the second temporal distance being the difference between the POC values of the co-located picture and POC values of the current picture containing the current block; deriving the movement vector updated based on the scaled movement vector and location of the current block; and deriving a movement vector of the current block based on the updated movement vector.

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