Quantization matrix can be used to adjust quantization of transform coefficients at different frequencies. In one embodiment, a single fixed parametric model, such as a polynomial is used to represent a quantization matrix. Modulation of bit cost and complexity is achieved by specifying only the n first polynomial coefficients, the remaining ones being implicitly set to zero or other default values. One form of the single fixed polynomial is a fully developed polynomial in (x,y), where x,y indicate the coordinates of a given coefficient in a quantization matrix, with terms ordered by increasing exponent. Since higher exponents are the last ones, reducing the number of polynomial coefficients reduces the degree of the polynomial, hence its complexity. The polynomial coefficients can be symmetrical in x and y, and thus reducing the number of polynomial coefficients that need to be signaled in the bitstream.

An encoder includes: circuitry; and memory coupled to the circuitry. The circuitry, in operation, stores a first parameter into a bitstream, the first parameter indicating, as a prediction mode, one of (i) a multiple prediction mode in which a prediction image is generated by overlapping an inter prediction image of a current block and an intra prediction image of the current block and (ii) one of a plurality of prediction modes including a non-rectangular mode in which a prediction image is generated for each non-rectangular partition in the current block, and encodes the current block according to the prediction mode.

An image decoding apparatus capable of more preferably applying inverse non-separable transform and techniques related thereto are provided. A video decoding apparatus includes a header decoder configured to decode a flag indicating a high accuracy coding mode from a sequence parameter set SPS, a scaling processing unit configured to perform inverse quantization on a transform coefficient for each transform block, and an inverse transform processing unit configured to perform inverse transform. The scaling processing unit switches whether a variable for indicating a range of the transform coefficient depends on a bit depth or does not depend on the bit depth, based on the flag and a size of the transform block.

An image decoding apparatus capable of more preferably applying inverse non-separable transform and techniques related thereto are provided. A video decoding apparatus includes a header decoder configured to decode a flag indicating a high accuracy coding mode from a sequence parameter set SPS, a scaling processing unit configured to perform inverse quantization on a transform coefficient for each transform block, and an inverse transform processing unit configured to perform inverse transform. The scaling processing unit switches whether a variable for indicating a range of the transform coefficient depends on a bit depth or does not depend on the bit depth, based on the flag and a size of the transform block.

A three-dimensional data storage method includes: acquiring one or more units in which an encoded stream generated by encoding point cloud data is stored; and storing the one or more units into a file. The storing includes storing, in control information for the file, information indicating that data stored in the file is data generated by encoding the point cloud data.

A three-dimensional data storage method includes: acquiring one or more units in which an encoded stream generated by encoding point cloud data is stored; and storing the one or more units into a file. The storing includes storing, in control information for the file, information indicating that data stored in the file is data generated by encoding the point cloud data.

A method of visual media processing video, includes determining that palette mode is to be used for processing a first portion of a video block and intra block copy (IBC) mode is to be used for processing a second portion of the video block, and performing further processing of the first portion of the video block using the palette mode and the second portion of the video using the IBC mode, wherein indications of the first portion of the video block processed using the palette mode and indications of the second portion of the video block processed using the IBC mode are included in a palette index identifying the first portion of the video block and the second portion of the video block.

A method of visual media processing video, includes determining that palette mode is to be used for processing a first portion of a video block and intra block copy (IBC) mode is to be used for processing a second portion of the video block, and performing further processing of the first portion of the video block using the palette mode and the second portion of the video using the IBC mode, wherein indications of the first portion of the video block processed using the palette mode and indications of the second portion of the video block processed using the IBC mode are included in a palette index identifying the first portion of the video block and the second portion of the video block.

A video decoding method comprises: deriving L0 and L1 motion vectors of a current block; deriving decoder-side motion vector refinement (DMVR) flag information indicating whether to apply a DMVR to the current block; when the DMVR flag information indicates that the DMVR is to be applied to the current block, deriving refined L0 and L1 motion vectors based on the L0 and L1 motion vectors by applying the DMVR to the current block; deriving prediction samples of the current block based on the refined L0 and L1 motion vectors; and generating reconstructed samples of the current block based on the predicted samples, wherein deriving DMVR flag information comprises deriving the DMVR flag information by applying the DMVR to the current block when the height of the current block is 8 or more, and when the values of L0 and L1 luma weighted prediction flag information are both 0.

A video decoding method comprises: deriving L0 and L1 motion vectors of a current block; deriving decoder-side motion vector refinement (DMVR) flag information indicating whether to apply a DMVR to the current block; when the DMVR flag information indicates that the DMVR is to be applied to the current block, deriving refined L0 and L1 motion vectors based on the L0 and L1 motion vectors by applying the DMVR to the current block; deriving prediction samples of the current block based on the refined L0 and L1 motion vectors; and generating reconstructed samples of the current block based on the predicted samples, wherein deriving DMVR flag information comprises deriving the DMVR flag information by applying the DMVR to the current block when the height of the current block is 8 or more, and when the values of L0 and L1 luma weighted prediction flag information are both 0.