A method and a device for encoding or decoding video data. It concerns more particularly the encoding according to a particular encoding mode using a decoder side motion vector derivation mode referenced as frame-rate up conversion mode or FRUC mode. In FRUC merge mode, the derivation process comprises a refinement step to increase the accuracy of the obtained motion vector at the sub-pixel level. This process involves the evaluation of different sub-pixel position around the obtained motion vector according to different patterns. The present invention has been devised to improve the known refinement step. It aims at improving the coding efficiency by considering the characteristics of the matching type and/or the signal inside the templates.

Several methods and systems for estimating motion in a plurality of multimedia pictures are disclosed. In an embodiment, at least one temporal distance between a multimedia picture and one or more reference pictures corresponding to the multimedia picture in a capture order associated with the plurality of multimedia pictures is computed. The at least one temporal distance is computed subsequent to an encoding of the multimedia picture. At least one motion estimation parameter is determined based on the at least one temporal distance. Motion associated with a subsequent multimedia picture to be encoded is estimated based on the at least one motion estimation parameter.

Several methods and systems for estimating motion in a plurality of multimedia pictures are disclosed. In an embodiment, at least one temporal distance between a multimedia picture and one or more reference pictures corresponding to the multimedia picture in a capture order associated with the plurality of multimedia pictures is computed. The at least one temporal distance is computed subsequent to an encoding of the multimedia picture. At least one motion estimation parameter is determined based on the at least one temporal distance. Motion associated with a subsequent multimedia picture to be encoded is estimated based on the at least one motion estimation parameter.

A video decoding method performed by a decoding apparatus includes the steps of: deriving control points (CP) for a current block; acquiring movement vectors for the CPs; deriving a sample unit movement vector in the current block on the basis of the acquired movement vectors; and deriving a prediction sample for the current block on the basis of the sample unit movement vector. According to the present invention, it is possible to effectively perform, through sample unit motion vectors, inter-prediction not only in a case where an image in the current block is plane-shifted but also in a case where there are various image distortions.

A video decoding method performed by a decoding apparatus includes the steps of: deriving control points (CP) for a current block; acquiring movement vectors for the CPs; deriving a sample unit movement vector in the current block on the basis of the acquired movement vectors; and deriving a prediction sample for the current block on the basis of the sample unit movement vector. According to the present invention, it is possible to effectively perform, through sample unit motion vectors, inter-prediction not only in a case where an image in the current block is plane-shifted but also in a case where there are various image distortions.

A video decoder including one or more processors configured to receive one or more bits, in a bitstream, that indicate the encoded current block of video data was encoded based on a unified candidate list that includes motion vector candidates based on one or more translational motion vectors, and motion vector candidates based on one or more affine motion vectors. A merge index represented in the bitstream may indicate which candidate in the unified candidate list is associated with the motionvector of the encoded current block of video data. Based on the merge index, the one or more processors are configured to select one or more motion vectors of a candidate from the unified candidate list, based on the merge index, where the candidate has one or more of the motion vectors corresponding to the translational motion vectors or affine motion vectors within the unified candidate list.

A video decoder including one or more processors configured to receive one or more bits, in a bitstream, that indicate the encoded current block of video data was encoded based on a unified candidate list that includes motion vector candidates based on one or more translational motion vectors, and motion vector candidates based on one or more affine motion vectors. A merge index represented in the bitstream may indicate which candidate in the unified candidate list is associated with the motionvector of the encoded current block of video data. Based on the merge index, the one or more processors are configured to select one or more motion vectors of a candidate from the unified candidate list, based on the merge index, where the candidate has one or more of the motion vectors corresponding to the translational motion vectors or affine motion vectors within the unified candidate list.

A picture decoding method includes determining motion information of a to-be-decoded block, obtaining a first decoding prediction block of the to-be-decoded block based on the motion information, performing motion search with first precision in the prediction reference picture block to obtain at least two second decoding prediction blocks, performing downsampling on the first decoding prediction block and the at least two second decoding prediction blocks to obtain a first sampling pixel array and at least two second sampling pixel arrays, respectively, calculating a difference between the first sampling pixel array and each of the second sampling pixel arrays, setting, as a target prediction motion vector, a motion vector corresponding to a second sampling pixel array with a minimum difference, obtaining a target decoding prediction block of the to-be-decoded block based on the target prediction motion vector, and decoding the to-be-decoded block based on the target decoding prediction block.

Several methods and systems for estimating motion in a plurality of multimedia pictures are disclosed. In an embodiment, at least one temporal distance between a multimedia picture and one or more reference pictures corresponding to the multimedia picture in a capture order associated with the plurality of multimedia pictures is computed. The at least one temporal distance is computed subsequent to an encoding of the multimedia picture. At least one motion estimation parameter is determined based on the at least one temporal distance. Motion associated with a subsequent multimedia picture to be encoded is estimated based on the at least one motion estimation parameter.

Several methods and systems for estimating motion in a plurality of multimedia pictures are disclosed. In an embodiment, at least one temporal distance between a multimedia picture and one or more reference pictures corresponding to the multimedia picture in a capture order associated with the plurality of multimedia pictures is computed. The at least one temporal distance is computed subsequent to an encoding of the multimedia picture. At least one motion estimation parameter is determined based on the at least one temporal distance. Motion associated with a subsequent multimedia picture to be encoded is estimated based on the at least one motion estimation parameter.