EP-4472206-B1 - ENCODING DEVICE AND ENCODING METHOD
Inventors
- ABE, KIYOFUMI
- NISHI, TAKAHIRO
- TOMA, TADAMASA
- KANOH, RYUICHI
- HASHIMOTO, TAKASHI
Dates
- Publication Date
- 20260513
- Application Date
- 20180920
Claims (2)
- An encoder (100), comprising: circuitry (160); and memory (162), wherein the circuitry (160) is configured to, using the memory (162), in inter prediction processing: derive a first motion vector of a first current block to be processed, using a motion vector of a previous block which has been previously processed; derive a second motion vector of the first current block by performing motion estimation in vicinity of a position specified by the first motion vector; and generate a prediction image of the first current block by performing motion compensation using the second motion vector, wherein a mode of the inter prediction processing is a merge mode, characterized in that the circuitry (160), in the inter prediction processing, is configured to derive a third motion vector of a second current block to be processed after the first current block, using the first motion vector of the first current block, when the second current block is included in a picture including the first current block, and derive the third motion vector of the second current block, using the second motion vector of the first current block, when the second current block is included in a picture different from the picture including the first current block, derive a fourth motion vector of the second current block by performing motion estimation in vicinity of a position specified by the third motion vector; and generate a prediction image of the second current block by performing motion compensation using the fourth motion vector.
- An encoding method, comprising: deriving (S203) a first motion vector of a first current block to be processed, using a motion vector of a previous block which has been previously processed; deriving (S204) a second motion vector of the first current block by performing motion estimation in vicinity of a position specified by the first motion vector; and generating (S208) a prediction image of the first current block by performing motion compensation using the second motion vector, wherein a mode of the inter prediction processing is a merge mode, characterized in that the encoding method further comprises: deriving a third motion vector of a second current block to be processed after the first current block, using the first motion vector of the first current block, when the second current block is included in a picture including the first current block, and deriving the third motion vector of the second current block, using the second motion vector of the first current block, when the second current block is included in a picture different from the picture including the first current block, deriving a fourth motion vector of the second current block by performing motion estimation in vicinity of a position specified by the third motion vector; and generating a prediction image of the second current block by performing motion compensation using the fourth motion vector.
Description
TECHNICAL FIELD The present disclosure relates to an encoder, a decoder, an encoding method, and a decoding method. BACKGROUND ART Conventionally, H.265 has been known as a standard for encoding videos. H.265 is also referred to as high efficiency video coding (HEVC). WO 2017/157281 A1 relates to motion vector derivation for video coding. In particular, in bilateral and temporal matching merge modes, LIST 0 and LIST_1 merge candidates are used as starting motion vectors. Further, in bilateral matching and temporal matching merge modes, a merge index is signaled, and the bilateral matching or template matching performs refinement search around the signaled merge candidate. Chen et al, "Output Algorithm of Joint Exploration Test Model 7 (JEM 7), JVET-G1001-v1 describes pattern matched motion vector derivation. In regard to DMVR processing for deriving a motion vector, for each of two reference pictures, the MV that yields the minimum template cost is considered as the updated MV of that list to replace the original one. Chen et al, "Further Improvement to HMKTA-1.0", VCEG-AZ07_v2) describes pattern matched motion vector derivation as well. Therein, as a starting point, a candidate with the smallest matching cost from the PU merge list, and deriving a motion vector through search around the starting point is selected. US 2016/286230 A1 relates to video coding. In particular, a video encoder generates a list of motion vector candidates, and uses one or more of the candidates of this candidate list as an initial motion vector. Motion vector candidates are associated with neighboring blocks. The encoder further refines the candidate by performing an additional motion search in an area indicated by the selected candidate to determine a derived motion vector. Citation List Non Patent Literature NPL 1: H.265 (ISO/IEC 23008-2 HEVC (High Efficiency Video Coding)) SUMMARY OF THE INVENTION TECHNICAL PROBLEM It is desired that such an encoding method and decoding method can reduce processing delay. The present disclosure has an object to provide a decoder, an encoder, a decoding method, and an encoding method capable of reducing processing delay. The invention is set out in the appended set of claims. SOLUTIONS TO PROBLEM An encoder according to an aspect of the present disclosure includes circuitry and memory. Using the memory, the circuitry: when encoding a current block in an inter prediction mode in which a decoder performs motion estimation, derives a first motion vector of the current block; stores, in the memory, the first motion vector derived; derives a second motion vector of the current block; and generates a prediction image of the current block by performing motion compensation using the second motion vector. In deriving the first motion vector, the first motion vector of the current block is derived using a first motion vector of a processed block. A decoder according to an aspect of the present disclosure includes circuitry and memory. Using the memory, the circuitry: when decoding a current block in an inter prediction mode in which the decoder performs motion estimation, derives a first motion vector of the current block; stores, in the memory, the first motion vector derived; derives a second motion vector of the current block; and generates a prediction image of the current block by performing motion compensation using the second motion vector. In deriving the first motion vector, the first motion vector of the current block is derived using a first motion vector of a processed block. Note that these general or specific aspects may be implemented by a system, a device, a method, an integrated circuit, a computer program, or a non-transitory computer-readable recording medium such as a compact disc read only memory (CD-ROM), or by any combination of systems, devices, methods, integrated circuits, computer programs, or recording media. ADVANTAGEOUS EFFECT OF INVENTION The present disclosure can provide a decoder, an encoder, a decoding method, and an encoding method capable of reducing processing delay. BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a block diagram illustrating a functional configuration of an encoder according to Embodiment 1.FIG. 2 illustrates one example of block splitting according to Embodiment 1.FIG. 3 is a chart indicating transform basis functions for each transform type.FIG. 4A illustrates one example of a filter shape used in ALF.FIG. 4B illustrates another example of a filter shape used in ALF.FIG. 4C illustrates another example of a filter shape used in ALF.FIG. 5A illustrates 67 intra prediction modes used in intra prediction.FIG. 5B is a flow chart for illustrating an outline of a prediction image correction process performed via OBMC processing.FIG. 5C is a conceptual diagram for illustrating an outline of a prediction image correction process performed via OBMC processing.FIG. 5D illustrates one example of FRUC.FIG. 6 is for illustrating pattern matching (bilateral matching) bet