# US 11,115,654 B2 · Encoder, decoder, encoding method, and decoding method > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,115,654 B2 - Document ID: US11115654B2 - Status: Granted - Kind: B2 - Application number: 16/901,869 - Filed: 2020-06-15 - Published: 2020-10-01 - Granted: 2021-09-07 - Earliest claimed: 2017-06-05 - Assignees: Panasonic Intellectual Property Corporation of America - Applicants: Panasonic Intellectual Property Corporation of America - Inventors: Kiyofumi Abe; Takahiro Nishi; Tadamasa Toma; Ryuichi Kanoh - Web page: https://patentgrep.com/patent/US11115654B2 ## CPC - H04N 19/105: Selection of the reference unit for prediction within a chosen coding or prediction mode, e.g. adaptive choice of position and number of pixels used for prediction - H04N 19/119: Adaptive subdivision aspects, e.g. subdivision of a picture into rectangular or non-rectangular coding blocks - H04N 19/139: Analysis of motion vectors, e.g. their magnitude, direction, variance or reliability - H04N 19/14: Coding unit complexity, e.g. amount of activity or edge presence estimation (H04N19/146 takes precedence) - H04N 19/176: the region being a block, e.g. a macroblock - H04N 19/52: by predictive encoding - H04N 19/573: Motion compensation with multiple frame prediction using two or more reference frames in a given prediction direction - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION ## Abstract An encoder is disclosed which includes circuitry and memory. Using the memory, the circuitry, in a first operating mode, derives first motion vectors for a first block obtained by splitting a picture, and generates a prediction image corresponding to the first block, with a bi-directional optical flow flag settable to true, and by referring to spatial gradients of luminance generated based on the first motion vectors. Using the memory, the circuitry, in a second operating mode, derives second motion vectors for a sub-block obtained by splitting a second block, the second block being obtained by splitting the picture, and generates a prediction image corresponding to the sub-block, with the bi-directional optical flow flag set to false. ## Claims ### Claim 1 A decoder comprising: circuitry; and memory, wherein, using the memory, the circuitry: in a first operating mode, derives first motion vectors for a first block obtained by splitting a picture, and generates a prediction image corresponding to the first block, with a bi-directional optical flow flag set to true, by referring to spatial gradients of luminance generated based on the first motion vectors; and in a second operating mode, derives second motion vectors for a sub-block obtained by splitting a second block, the second block being obtained by splitting the picture, and generates a prediction image corresponding to the sub-block, with the bi-directional optical flow flag set to false. ### Claim 2 (depends on 1) The decoder according to claim 1, wherein the circuitry: in the first operating mode, derives the first motion vectors in a unit of the first block using a first inter frame prediction mode; and in the second operating mode, derives the second motion vectors in a unit of the sub-block using a second inter frame prediction mode different from the first inter frame prediction mode. ### Claim 3 (depends on 2) The decoder according to claim 2, wherein the second inter frame prediction mode uses a degree of matching between two reconstructed images of two regions in two different pictures. ### Claim 4 (depends on 3) The decoder according to claim 3, wherein the first inter frame prediction mode is one of (i) a third inter frame prediction mode that uses a degree of matching between a reconstructed image of a region in a current picture neighboring a current block, and a reconstructed image of a region in a reference picture, and (ii) a fourth inter frame prediction mode that uses a degree of matching between two reconstructed images of two regions in two different reference pictures, and the second inter frame prediction mode is the other of the third inter frame prediction mode and the fourth inter frame prediction mode. ### Claim 5 (depends on 4) The decoder according to claim 4, wherein the first inter frame prediction mode is the third inter frame prediction mode, and the second inter frame prediction mode is the fourth inter frame prediction mode. ### Claim 6 (depends on 3) The decoder according to claim 3, wherein the first inter frame prediction mode obtains, from an encoded bitstream, information for identifying the first motion vectors in the unit of the first block, and derives the first motion vectors using the information. ### Claim 7 A decoding method, comprising: in a first operating mode, deriving first motion vectors for a first block obtained by splitting a picture, and generating a prediction image corresponding to the first block, with a bi-directional optical flow flag set to true, by referring to spatial gradients of luminance generated based on the first motion vectors; and in a second operating mode, deriving second motion vectors for a sub-block obtained by splitting a second block, the second block being obtained by splitting the picture, and generating a prediction image corresponding to the sub-block, with the bi-directional optical flow flag set to false. ### Claim 8 (depends on 7) The decoding method according to claim 7, wherein a size of the first block obtained by splitting the picture is variable. ### Claim 9 (depends on 1) The decoder according to claim 1, wherein a size of the first block obtained by splitting the picture is variable.