Methods, systems and device for hash-based motion estimation in video coding are described. An exemplary method of video processing includes determining, for a conversion between a current block of a video and a bitstream representation of the video, motion information associated with the current block using a hash-based motion search, a size of the current block being M×N, M and N being positive integers and M being not equal to N, applying, based on the motion information and a video picture comprising the current block, a prediction for the current block, and performing, based on the prediction, the conversion.

The present disclosure describes techniques for coding and decoding video in which a plurality of coding hypotheses are developed for an input pixel block of frame content. Each coding hypothesis may include generation of prediction data for the input pixel block according to a respective prediction search. The input pixel block may be coded with reference to a prediction block formed from prediction data derived according to plurality of hypotheses. Data of the coded pixel block may be transmitted to a decoder along with data identifying a number of the hypotheses used during the coding to a channel. At a decoder, an inverse process may be performed, which may include generation of a counterpart prediction block from prediction data derived according to the hypothesis identified with the coded pixel block data, then decoding of the coded pixel block according to the prediction data.

The present disclosure describes techniques for coding and decoding video in which a plurality of coding hypotheses are developed for an input pixel block of frame content. Each coding hypothesis may include generation of prediction data for the input pixel block according to a respective prediction search. The input pixel block may be coded with reference to a prediction block formed from prediction data derived according to plurality of hypotheses. Data of the coded pixel block may be transmitted to a decoder along with data identifying a number of the hypotheses used during the coding to a channel. At a decoder, an inverse process may be performed, which may include generation of a counterpart prediction block from prediction data derived according to the hypothesis identified with the coded pixel block data, then decoding of the coded pixel block according to the prediction data.

A video decoder can be configured to determine that a current block of the video data is coded in a bi-prediction inter mode; receive a first syntax element identifying a motion vector predictor from a first candidate list of motion vector predictors; receive a second syntax element identifying a motion vector difference; determine a first motion vector for the current block based on the motion vector predictor and the motion vector difference; determine a second motion vector for the current block from a second list of candidate motion vector predictors based on bilateral matching; and determine a prediction block for the current block using the first motion vector and the second motion vector.

Motion information for an internal sub-block of a larger block can be derived for use in encoding or decoding the video block or a coding unit by using the motion information for sub-blocks on the left or top edge of the coding block. The left column of edge sub-blocks and the top row of sub-blocks has motion information, such as motion vectors, derived using such techniques as template matching. The motion vectors of these edge sub-blocks are used in deriving the motion vectors of internal sub-blocks, which leads to better prediction and improved coding efficiency. In another embodiment, other motion information for internal sub-blocks is derived from corresponding information of the edge sub-blocks.

An image processing apparatus and an image processing method make it possible to suppress increase of the load of template matching. For each of motion vector candidates of accuracy rougher than accuracy of a motion vector candidate list, template matching between a template of a current block and a template of a reference block is performed to derive a cost, and elements of the motion vector candidate list are sorted on the basis of the derived costs of the motion vector candidates. Alternatively, for each of motion vector candidates of accuracy rougher than accuracy of a motion vector candidate list, template matching between a template of a current block and a template of a search point is performed to derive a cost, and a modification motion vector candidate is derived on the basis of the derived costs of the motion vector candidates.

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.

A video encoding method of estimating a motion vector of a current block in a current frame includes identifying a reference block in a reference frame, a first location of the current block within the current frame corresponding to a second location of the reference block within the reference frame, setting a search range in the reference frame, searching for candidate blocks from the search range of the reference frame, each of the candidate blocks satisfying a corresponding first motion estimation criterion of first motion estimation criteria, searching for a prediction block from among the candidate blocks, the prediction block satisfying a second motion estimation criterion, estimating, as the motion vector of the current block, a motion vector corresponding to a displacement between the reference block and the prediction block, and encoding the current block based on the estimated motion vector.

Embodiments of the present disclosure disclose a video image processing method performed at a computing device, including: after performing deblocking and sample adaptive offset on a reconstructed coding tree unit within a target image frame, performing half pixel estimation on the coding tree unit of the target image frame to obtain an optimal half pixel location having a minimum rate distortion cost; dividing a surrounding area of the optimal half pixel location into four partitions; selecting, among the four partitions according to rate distortion costs respectively of four half pixel locations adjacent to the optimal half pixel location, a first partition used for quarter pixel estimation; performing quarter pixel estimation on the first partition according to the optimal half pixel location, to obtain an optimal quarter pixel location having a minimum rate distortion cost within the first partition; and performing motion compensation to the target image frame by using at least one of the optimal half pixel location and the optimal quarter pixel location as a motion estimation result.

Embodiments of the present disclosure disclose a video image processing method performed at a computing device, including: after performing deblocking and sample adaptive offset on a reconstructed coding tree unit within a target image frame, performing half pixel estimation on the coding tree unit of the target image frame to obtain an optimal half pixel location having a minimum rate distortion cost; dividing a surrounding area of the optimal half pixel location into four partitions; selecting, among the four partitions according to rate distortion costs respectively of four half pixel locations adjacent to the optimal half pixel location, a first partition used for quarter pixel estimation; performing quarter pixel estimation on the first partition according to the optimal half pixel location, to obtain an optimal quarter pixel location having a minimum rate distortion cost within the first partition; and performing motion compensation to the target image frame by using at least one of the optimal half pixel location and the optimal quarter pixel location as a motion estimation result.