An image encoding device and a method, and an image decoding device and a method that are designed to improve encoding efficiency in IntraBC. A screen is divided into four slices (Slices #0 through #3). In a case where reference to a different slice is prohibited, the range that can be referred to from the current CTU in Slice #2 is only the decoded portion in Slice #2, and therefore, any block in Slice #1 cannot be referred to, for example. In the case of the present technology, on the other hand, decoded different slices (Slice #0 and Slice #1)are included in the referable range, and accordingly, a block in Slice #1 can be referred to from the current CTU in Slice #2.

A method of encoding a video stream in a video encoder is provided that includes computing an offset into a transform matrix based on a transform block size, wherein a size of the transform matrix is larger than the transform block size, and wherein the transform matrix is one selected from a group consisting of a DCT transform matrix and an IDCT transform matrix, and transforming a residual block to generate a DCT coefficient block, wherein the offset is used to select elements of rows and columns of a DCT submatrix of the transform block size from the transform matrix.

A method of encoding a video stream in a video encoder is provided that includes computing an offset into a transform matrix based on a transform block size, wherein a size of the transform matrix is larger than the transform block size, and wherein the transform matrix is one selected from a group consisting of a DCT transform matrix and an IDCT transform matrix, and transforming a residual block to generate a DCT coefficient block, wherein the offset is used to select elements of rows and columns of a DCT submatrix of the transform block size from the transform matrix.

In order to provide low-load, efficient coding technology, a moving-picture decoding device includes a spatial motion information candidate derivation unit configured to derive a spatial motion information candidate from motion information of a block neighboring a decoding target block in a space domain and a history-based motion information candidate derivation unit configured to derive a history-based motion information candidate from a memory where motion information of a decoded block is retained, wherein the history-based motion information candidate derivation unit preferentially derives old motion information without making a comparison of the motion information with the spatial motion information candidate.

In order to provide low-load, efficient coding technology, a moving-picture decoding device includes a spatial motion information candidate derivation unit configured to derive a spatial motion information candidate from motion information of a block neighboring a decoding target block in a space domain and a history-based motion information candidate derivation unit configured to derive a history-based motion information candidate from a memory where motion information of a decoded block is retained, wherein the history-based motion information candidate derivation unit preferentially derives old motion information without making a comparison of the motion information with the spatial motion information candidate.

A three-dimensional data encoding method includes: performing motion compensation on a plurality of encoded point clouds; merging the plurality of encoded point clouds that have been motion compensated to generate a reference point cloud; generating an N-ary tree structure of a current point cloud, where N is an integer greater than or equal to 2; and encoding the N-ary tree structure of the current point cloud using the reference point cloud.

A three-dimensional data encoding method includes: performing motion compensation on a plurality of encoded point clouds; merging the plurality of encoded point clouds that have been motion compensated to generate a reference point cloud; generating an N-ary tree structure of a current point cloud, where N is an integer greater than or equal to 2; and encoding the N-ary tree structure of the current point cloud using the reference point cloud.

The present invention relates to a method for performing entropy decoding on a video signal including a current block. The method comprises the steps of: deriving affine coding information and/or affine prediction mode information of a left block and/or an upper block which are adjacent to the current block; determining a context index of a syntax element associated with an affine prediction of the current block on the basis of at least one of the affine coding information and/or the affine prediction mode information of the left block and/or the upper block; and entropy decoding the syntax element associated with the affine prediction of the current block on the basis of the context index.

The present invention relates to a method for performing entropy decoding on a video signal including a current block. The method comprises the steps of: deriving affine coding information and/or affine prediction mode information of a left block and/or an upper block which are adjacent to the current block; determining a context index of a syntax element associated with an affine prediction of the current block on the basis of at least one of the affine coding information and/or the affine prediction mode information of the left block and/or the upper block; and entropy decoding the syntax element associated with the affine prediction of the current block on the basis of the context index.

Devices, systems and methods for digital video coding, which includes an overlapped block motion compensation (OBMC) process based on spatially neighboring blocks, are described. An exemplary method for video processing includes generating a motion information associated with a current video block; generating, based on a weighted sum of at least two temporary prediction blocks, a prediction block for the current video block, a first of the at least two temporary prediction blocks being based on the motion information, and a second of the at least two temporary prediction blocks being based on an intra prediction mode of a neighboring block; and performing, based on the prediction block, a conversion between the current video block and a bitstream representation of the current video block.