# US 12,120,295 B2 · Video decoding method using bi-prediction and device therefor > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,120,295 B2 - Document ID: US12120295B2 - Status: Granted - Kind: B2 - Application number: 18/218,925 - Filed: 2023-07-06 - Published: 2023-11-02 - Granted: 2024-10-15 - Earliest claimed: 2019-06-24 - Assignees: LG Electronics Inc. - Applicants: LG Electronics Inc. - Inventors: Naeri Park; Junghak Nam; Hyeongmoon Jang - Web page: https://patentgrep.com/patent/US12120295B2 ## 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 19/109: among a plurality of temporal predictive coding modes - H04N 19/159: Prediction type, e.g. intra-frame, inter-frame or bidirectional frame prediction - H04N 19/176: the region being a block, e.g. a macroblock - H04N 19/196: being specially adapted for the computation of encoding parameters, e.g. by averaging previously computed encoding parameters (processing of motion vectors H04N19/513) - H04N 19/527: Global motion vector estimation - H04N 19/573: Motion compensation with multiple frame prediction using two or more reference frames in a given prediction direction - H04N 19/70: characterised by syntax aspects related to video coding, e.g. related to compression standards - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION ## Abstract According to the disclosure of the present document, when the inter-prediction type of the current block indicates biprediction, weight index information for a candidate in a merge candidate list or sub-block merge candidate list can be derived, and coding efficiency can be raised. ## Claims ### Claim 1 A decoding apparatus for image decoding, the decoding apparatus comprising: a memory; and at least one processor connected to the memory, the at least one processor configured to: obtain image information including inter-prediction mode information through a bitstream; generate a sub-block merge candidate list of a current block based on the inter-prediction mode information; select one candidate from among the candidates included in the sub-block merge candidate list; and generate prediction samples of the current block based on a weight index for the selected candidate, wherein the sub-block merge candidate list includes an inherited affine merge candidate and a constructed affine merge candidate, wherein the inherited affine merge candidate is derived based on control point motion vectors of a neighboring block of the current block, wherein the constructed affine merge candidate is generated based on at least two of a control point CP0 related to a top-left corner of the current block, a control point CP1 related to a top-right corner of the current block, a control point CP2 related to a bottom-left corner of the current block and a control point CP3 related to a bottom-right corner of the current block, wherein based on a case that the constructed affine merge candidate is generated based on {CP0, CP2}, a weight index for the constructed affine merge candidate is equal to a weight index for the CP0, wherein based on a case that the constructed affine merge candidate is generated based on {CP1, CP2, CP3}, the weight index for the constructed affine merge candidate is equal to a weight index for the CP1, and wherein the constructed affine merge candidate is inserted after the inherited affine merge candidate in the sub-block merge candidate list. ### Claim 2 (depends on 1) The decoding apparatus of claim 1, wherein the weight index for the CP0 corresponds to a weight index of a block used for deriving a motion vector for the CP0 among neighboring blocks of the CP0, and the neighboring blocks of the CP0 include a top-left corner neighboring block of the current block, a left neighboring block adjacent to a bottom of the top-left corner neighboring block, and a top neighboring block adjacent to a right of the top-left corner neighboring block. ### Claim 3 (depends on 1) The decoding apparatus of claim 1, wherein the weight index for the CP1 corresponds to a weight index of a block used for deriving a motion vector for the CP1 among neighboring blocks of the CP1, and the neighboring blocks of the CP1 include a top-right corner neighboring block of the current block and a top neighboring block adjacent to a left of the top-right corner neighboring block. ### Claim 4 (depends on 1) The decoding apparatus of claim 1, wherein the candidates include a pair-wise candidate, and the pair-wise candidate is derived based on a first candidate and a second candidate in the merge candidate list, and a weight index for the pair-wise candidate is derived based on a weight index of the first candidate. ### Claim 5 (depends on 1) The decoding apparatus of claim 1, wherein the candidates include a subblock-based temporal merge candidate, and a weight index for the subblock-based temporal merge candidate is derived based on a weight index of a left neighboring block of the current block. ### Claim 6 (depends on 1) The decoding apparatus of claim 1, wherein the candidates include a subblock-based temporal merge candidate, and a weight index for the subblock-based temporal merge candidate is derived as 0. ### Claim 7 (depends on 1) The decoding apparatus of claim 1, wherein the candidates include a subblock-based temporal merge candidate, a weight index for the subblock-based temporal merge candidate is derived based on a weight index of a center block in a col block, the col block is positioned in a reference picture different from a current picture in which the current block is positioned and includes a block derived based on a motion vector of a left neighboring block of the current block, and the center block includes a bottom-right subblock among four subblocks positioned in a center of the col block. ### Claim 8 An encoding apparatus for image encoding, the encoding apparatus comprising: a memory; and at least one processor connected to the memory, the at least one processor configured to: determine an inter-prediction mode of a current block and generating inter prediction mode information indicating the inter-prediction mode; generate a sub-block merge candidate list of the current block based on the inter-prediction mode; generate selection information indicating one of candidates included in the sub-block merge candidate list; and encode image information including the inter-prediction mode information and the selection information, wherein the sub-block merge candidate list includes an inherited affine merge candidate and a constructed affine merge candidate, wherein the inherited affine merge candidate is derived based on control point motion vectors of a neighboring block of the current block, wherein the constructed affine merge candidate is generated based on at least two of a control point CP0 related to a top-left corner of the current block, a control point CP1 related to a top-right corner of the current block, a control point CP2 related to a bottom-left corner of the current block and a control point CP3 related to a bottom-right corner of the current block, wherein based on a case that the constructed affine merge candidate is generated based on {CP0, CP2}, a weight index for the constructed affine merge candidate is equal to a weight index for the CP0, wherein based on a case that the constructed affine merge candidate is generated based on {CP1, CP2, CP3}, the weight index for the constructed affine merge candidate is equal to a weight index for the CP1, and wherein the constructed affine merge candidate is inserted after the inherited affine merge candidate in the sub-block merge candidate list. ### Claim 9 (depends on 8) The encoding apparatus of claim 8, wherein the weight index for the CP0 corresponds to a weight index of a block used for deriving a motion vector for the CP0 among neighboring blocks of the CP0, and the neighboring blocks of the CP0 include a top-left corner neighboring block of the current block, a left neighboring block adjacent to a bottom of the top-left corner neighboring block, and a top neighboring block adjacent to a right of the top-left corner neighboring block. ### Claim 10 (depends on 8) The encoding apparatus of claim 8, wherein the weight index for the CP1 corresponds to a weight index of a block used for deriving a motion vector for the CP1 among neighboring blocks of the CP1, and the neighboring blocks of the CP1 include a top-right corner neighboring block of the current block and a top neighboring block adjacent to a left of the top-right corner neighboring block. ### Claim 11 (depends on 8) The encoding apparatus of claim 8, wherein the candidates include a pair-wise candidate, and the pair-wise candidate is derived based on a first candidate and a second candidate in the merge candidate list, and a weight index for the pair-wise candidate is derived based on a weight index of the first candidate. ### Claim 12 (depends on 8) The encoding apparatus of claim 8, wherein the candidates include a subblock-based temporal merge candidate, and a weight index for the subblock-based temporal merge candidate is derived based on a weight index of a left neighboring block of the current block. ### Claim 13 (depends on 8) The encoding apparatus of claim 8, wherein the candidates include a subblock-based temporal merge candidate, and a weight index for the subblock-based temporal merge candidate is derived as 0. ### Claim 14 (depends on 8) The encoding apparatus of claim 8, wherein the candidates include a subblock-based temporal merge candidate, a weight index for the subblock-based temporal merge candidate is derived based on a weight index of a center block in a col block, the col block is positioned in a reference picture different from a current picture in which the current block is positioned and includes a block derived based on a motion vector of a left neighboring block of the current block, and the center block includes a bottom-right subblock among four subblocks positioned in a center of the col block. ### Claim 15 A transmission method for image data, the method comprising: obtaining, by a transmission apparatus, a bitstream for the image, wherein the bitstream is generated based on determining an inter-prediction mode of a current block and generating inter prediction mode information indicating the inter-prediction mode, generating a sub-block merge candidate list of the current block based on the inter-prediction mode, generating selection information indicating one of candidates included in the sub-block merge candidate list, and encoding image information including the inter-prediction mode information and the selection information; and transmitting, by the transmitting apparatus, the data comprising the bitstream, wherein the sub-block merge candidate list includes an inherited affine merge candidate and a constructed affine merge candidate, wherein the inherited affine merge candidate is derived based on control point motion vectors of a neighboring block of the current block, wherein the constructed affine merge candidate is generated based on at least two of a control point CP0 related to a top-left corner of the current block, a control point CP1 related to a top-right corner of the current block, a control point CP2 related to a bottom-left corner of the current block and a control point CP3 related to a bottom-right corner of the current block, wherein based on a case that the constructed affine merge candidate is generated based on {CP0, CP2}, a weight index for the constructed affine merge candidate is equal to a weight index for the CP0, wherein based on a case that the constructed affine merge candidate is generated based on {CP1, CP2, CP3}, the weight index for the constructed affine merge candidate is equal to a weight index for the CP1, and wherein the constructed affine merge candidate is inserted after the inherited affine merge candidate in the sub-block merge candidate list.