Abstract: This application provides video picture prediction methods and apparatuses. In an implementation, a method for encoding of video picture comprises generating a bitstream for video signals, the bitstream comprises a plurality of syntax elements, wherein the plurality of syntax elements comprises a first identifier indicating that an affine motion model based motion compensation is enabled for a video sequence including a picture block to be processed, wherein a second identifier is conditionally signaled at least based on a value of the first identifier, wherein a false value of the second identifier indicates that a 6-parameter affine motion model based motion compensation is disabled for the video sequence, and wherein a true value of the second identifier indicates that the 6-parameter affine motion model based motion compensation is enabled for the video sequence.

Abstract: An intra prediction method includes obtaining respective intra prediction modes or texture distributions of P reconstructed picture blocks in a surrounding region of a current block; obtaining, based on the respective intra prediction modes or texture distributions of the P reconstructed picture blocks, Q priori candidate intra prediction modes of the current block and Q probability values; obtaining, based on M probability values corresponding to M priori candidate intra prediction modes, M weighting factors corresponding to the M priori candidate intra prediction modes; separately performing intra prediction based on the M priori candidate intra prediction modes to obtain M predicted values; and obtaining a predicted value of the current block based on a weighted summation of the M predicted values and the corresponding M weighting factors.

Abstract: A video encoder, a video decoder, and a corresponding method are provided. The method includes: parsing a bitstream to obtain an index, where the index indicates a target candidate motion vector group of a current coding block; determining the target candidate motion vector group in an affine candidate motion vector list based on the index, where the affine candidate motion vector list includes at least a first candidate motion vector group, the first candidate motion vector group is obtained based on a first group of control points of a first neighboring affine coding block, and the first group of control points is determined based on a CTU located relative to the current coding block, wherein the first neighboring affine coding block is located in the CTU; and predicting a predicted sample value of the current coding block based on the target candidate motion vector group.

Abstract: A picture prediction method is provided, which includes: obtaining initial motion information of a current picture block; determining, based on a matching cost criterion, that positions of a pair of reference blocks are a position of a target forward reference block of the current picture block and a position of a target backward reference block of the current picture block, where positions of each pair of reference blocks include a position of a forward reference block and a position of a backward reference block; and for the positions of each pair of reference blocks, a first position offset and a second position offset are in a mirror relationship; and obtaining a predicted value of a pixel value of the current picture block based on a pixel value of the target forward reference block and a pixel value of the target backward reference block.

Abstract: An inter prediction method, including: when a prediction mode of a to-be-processed picture block is an affine motion model-based advanced motion vector prediction mode, obtaining control point motion vectors of the to-be-processed picture block, where the control point motion vectors meet preset first motion vector resolution and/or first motion vector bit depth; then, deriving a motion vector of each motion compensation unit in the to-be-processed picture block based on the control point motion vectors; and obtaining a reconstructed block of the to-be-processed picture block based on the motion vector of each motion compensation unit.

Abstract: A video decoding method includes obtaining a to-be-entropy-decoded syntax element in a current block by parsing a received bitstream, where the to-be-entropy-decoded syntax element includes a syntax element 1 or a syntax element 2 in the current block, obtaining a context model corresponding to the to-be-entropy-decoded syntax element, where both of a context model corresponding to the syntax element 1 and a context model corresponding to the syntax element 2 are determined from the same preset context model set, entropy decoding the to-be-entropy-decoded syntax element based on the context model corresponding to the to-be-entropy-decoded syntax element, and obtaining a reconstructed image of the current block based on the syntax element obtained by entropy decoding.

Abstract: A motion vector prediction method includes parsing a bitstream to obtain an index value of a candidate motion vector list and constructing the candidate motion vector list that includes. candidate motion vectors of K control points of a current block. The candidate motion vectors of K control points are obtained based on a 2N-parameter affine transform model used for a neighboring block of the current block, where N and K are integers greater than or equal to 2 and less than or equal to 4 with N not being equal to K. The method further includes determining, in the candidate motion vector list, target candidate motion vectors of the K control points based on the index value and obtaining a predicted motion vector of each subblock of the current block based on the target candidate motion vectors of the K control points.

Abstract: A reference frame obtaining method includes determining a first reference frame list and a second reference frame list of a current picture block, determining, from the first reference frame list, whether an X-directional reference frame x1 satisfying a condition A1 exists, determining, from the second reference frame list, whether a Y-directional reference frame y1 satisfying a condition B1 exists, and in response to determining that the X-directional reference frame x1 exists and determining that the Y-directional reference frame y1 exists, obtaining index values (R1, R2) of bidirectional reference frames of the current picture block.

Abstract: This disclosure discloses a method for obtaining a candidate motion vector list, an apparatus, an encoder, and a decoder. The method for obtaining a candidate motion vector list comprises: when a first candidate picture block is encoded/decoded and an inter prediction mode is used, determining whether a reference picture of the first candidate picture block is the same as a reference picture of a current block; and constructing a candidate motion vector list of the current block based on a determining result; when the reference picture of the first candidate picture block is different from the reference picture of the current block, the MV of the first candidate picture block is not used to construct the list. Implementing this disclosure can reduce complexity of a motion information derivation process, and improve coding efficiency.

Abstract: This application provides a motion vector obtaining method and apparatus. The method includes: determining a target offset vector of a block and identifier information of a target picture, wherein the block comprises at least one sub-block; determining a location of the sub-block; determining, as a target location coordinate value of a collocated sub-block, a location coordinate value obtained by performing a clipping operation on an initial location coordinate value in a range, wherein the initial location coordinate value is based on the location of the sub-block and the target offset vector; and obtaining a motion vector of the sub-block based on a motion vector corresponding to the target location coordinate value. Thus, a range of the target offset vector is limited, so that a quantity of memory read times can be reduced in a process of obtaining the motion vector of the collocated sub-block.

Abstract: A video encoder, a video decoder, and a corresponding method are provided. The method includes: parsing a bitstream to obtain an index, where the index indicates a target candidate motion vector group of a current coding block; determining the target candidate motion vector group in an affine candidate motion vector list based on the index, where the affine candidate motion vector list includes at least a first candidate motion vector group, the first candidate motion vector group is obtained based on a first group of control points of a first neighboring affine coding block, and the first group of control points is determined based on a CTU located relative to the current coding block, wherein the first neighboring affine coding block is located in the CTU; and predicting a predicted sample value of the current coding block based on the target candidate motion vector group.

Abstract: A motion vector prediction method based on an affine motion model and a device are provided. The method includes: obtaining one spatial reference block of a to-be-processed picture block; determining a plurality of preset subblock locations of the spatial reference block; obtaining motion vectors corresponding to preset pixel locations of the to-be-processed picture block that are extrapolated from motion vectors corresponding to the preset subblock locations; and obtaining motion vectors corresponding to a plurality of subblock locations of the to-be-processed picture block that are interpolated from the motion vectors corresponding to the preset pixel locations. According to this application, prediction accuracy in coding can be improved, and coding efficiency can be improved.

Abstract: A method of coding is described. The method can include obtaining a bitstream for a current picture, obtaining a value of a first indicator for the current picture according to the bitstream indicating a slice type, and obtaining a value of a second indicator for the current picture according to the bitstream indicating whether a weighted prediction parameter is present in a picture header or slice header of the bitstream. The method can also include parsing a value of the weighted prediction parameter for a current block of a current slice of the current picture from the bitstream. Furthermore, the method can include predicting the current block according to the value of the weighted prediction parameter.

Abstract: A picture prediction method is provided, which includes: obtaining initial motion information of a current picture block; determining, based on a matching cost criterion, that positions of a pair of reference blocks are a position of a target forward reference block of the current picture block and a position of a target backward reference block of the current picture block, where positions of each pair of reference blocks include a position of a forward reference block and a position of a backward reference block; and for the positions of each pair of reference blocks, a first position offset and a second position offset are in a mirror relationship; and obtaining a predicted value of a pixel value of the current picture block based on a pixel value of the target forward reference block and a pixel value of the target backward reference block.

Abstract: A video data inter prediction method is provided, which includes: determining a candidate motion information list of a current picture block, where the candidate motion information list includes at least one first candidate motion information group, at least one second candidate motion information group, the first candidate motion information group is a motion information group determined based on motion information of preset locations on a first neighboring picture block of the current picture block and a motion model of the first neighboring picture block, the second candidate motion information group is a set of motion information of at least two sample locations that are respectively neighboring to at least two preset locations on the current picture block; determining target motion information from the candidate motion information list; and performing inter prediction on the current picture block based on the target motion information.

Abstract: This disclosure discloses a method for obtaining a candidate motion vector list, an apparatus, an encoder, and a decoder. The method for obtaining a candidate motion vector list comprises: when a first candidate picture block is encoded/decoded and an inter prediction mode is used, determining whether a reference picture of the first candidate picture block is the same as a reference picture of a current block; and constructing a candidate motion vector list of the current block based on a determining result; when the reference picture of the first candidate picture block is different from the reference picture of the current block, the MV of the first candidate picture block is not used to construct the list. Implementing this disclosure can reduce complexity of a motion information derivation process, and improve coding efficiency.

Abstract: The present disclosure provides a video image decoding method in which a size of an affine motion compensation image sub-block in an affine image block is determined based on a motion vector difference, motion vector precision, a distance between control points in the affine image block, and a size of the affine image block, where the size includes a length in a horizontal direction and a length in a vertical direction, so that a length of the affine image block in a horizontal/vertical direction is an integer multiple of the length of the affine motion compensation image sub-block in the horizontal/vertical direction.

Abstract: Image encoding and decoding methods, apparatuses and computer-readable media are described. An example image encoding method includes: determining N encoded units from adjacent encoded units of a to-be-encoded unit according to a first preset rule, where a motion prediction mode of the N encoded units is the same as that of the to-be-encoded unit; generating an nth motion vector group by using a first preset algorithm and based on a motion vector of an nth encoded unit; determining, from obtained N motion vector groups according to a second preset rule, one motion vector group as an optimal motion vector group; determining a prediction sample value of each sample unit in the to-be-encoded unit by using a second preset algorithm and based on the optimal motion vector group; and encoding a prediction residual of each sample unit and an index identifier of the optimal motion vector group, to obtain a bitstream corresponding to the to-be-encoded unit.

Abstract: This application provides a video picture prediction method and apparatus, to resolve a problem in a conventional technology that a length of a coded video sequence is increased. The first type of identifier may be added to a bitstream. The first type of identifier is used to indicate whether an affine motion model-based inter prediction mode is enabled for a video picture. For a video picture or a picture block included in the slice for which the affine motion model does not need to be used, a parameter, related to the affine motion model, of the picture block may not need to be transmitted. On a decoder side, during decoding of the picture block, the parameter related to the affine motion model does not need to be parsed. This can reduce load of a decoder, increase a processing speed, and decrease a processing time.

Abstract: An image encoding method includes: determining N encoded units from adjacent encoded units of a to-be-encoded unit according to a first preset rule, where a motion prediction mode of the N encoded units is the same as that of the to-be-encoded unit, generating an nth motion vector group by using a first preset algorithm and based on a motion vector of an nth encoded unit; determining, from obtained N motion vector groups according to a second preset rule, one motion vector group as an optimal motion vector group; determining a prediction sample value of each sample unit in the to-be-encoded unit by using a second preset algorithm and based on the optimal motion vector group; and encoding a prediction residual of each sample unit and an index identifier of the optimal motion vector group, to obtain a bitstream corresponding to the to-be-encoded unit.