An apparatus determines a value of a coordinate for a sample is outside a range of values of the coordinate for samples in a reference region. The sample is displaced relative to a current block by an amount indicated by a block vector predictor (BVP). The apparatus adjusts a component, corresponding to a direction of the coordinate, of the BVP to have an adjusted value closer to the range of values of the coordinate for the samples in the reference region based on the determining. The apparatus uses the BVP, with the component adjusted to have the adjusted value, to determine or predict a block vector (BV) for the current block.

Methods and apparatuses for video coding are provided. The method includes that a decoder determines whether one or more reference picture lists are signaled in a picture header (PH) associated with a picture and whether the one or more reference picture lists indicate that one or more slices associated with the picture are bi-predictive. The method further includes that the decoder adds one or more constraints to one or more syntax elements in the PH in response to determining that the one or more reference picture lists are signaled in the PH and the one or more reference picture lists indicate that the one or more slices are not bi-predictive.

The present disclosure provides a video picture coding method, a video picture decoding method, a coding device, and a decoding device. The method includes: determining a distance between control points for an affine picture block; determining a motion vector difference for the affine picture block, motion vectors of the control points being used to determine the motion vector difference; and performing coding processing on the affine picture block over a size that includes a horizontal length and a vertical length, wherein the horizontal length and the vertical length vary based on the distance between the control points, the motion vector difference, and a motion vector precision.

In a method for video decoding in a decoder, a first motion vector and a second motion vector for a first block in a current picture are received. The first motion vector is indicative of a first reference block in a first picture, and the second motion vector is indicative of a second reference block in a second picture. A bilateral template is generated based on a weighted combination of the first reference block and the second reference block. A refined first motion vector and a refined second motion vector are determined based on the bilateral template, reference blocks in the first picture and reference blocks in the second picture respectively. An initial motion vector of a second block that is ceded after the first block is determined according to at least one of the first motion vector and the second motion vector for the first block.

Methods and system, including decoders and encoders, for interprediction. In one aspect, a method includes selecting reference samples based on motion information of a current picture block of a current picture, deriving first interpolated samples by performing a first interpolation on the selected reference samples, deriving an integer distance delta motion vector for a target sub-prediction unit (PU) by performing integer-distance MVR, deriving M×M pixel matrix flow vectors by performing BPOF, for each M×M pixel matrix in the target sub-PU, based on the first interpolated samples and the integer distance delta motion vector, deriving second interpolated samples by performing a second interpolation on the reference samples, computing at least one correction parameter for the target sub-PU based on the M×M pixel matrix flow vectors, the first interpolated samples and the second interpolated samples, and performing bi-prediction based on the second interpolated samples and the at least one correction parameter.

Methods and apparatus of video coding using sub-block based affine mode are disclosed. According to this method, control-point motion vectors (MVs) associated with the affine mode are determined for a block. A sub-block MV is derived for a target sub-block of the block from the control- point MVs for the block. A prediction offset is determined for a target pixel of the target sub-block using information comprising a pixel MV offset from the sub-block MV for the target pixel according to Prediction Refinement with Optical Flow (PROF). The target pixel of the target sub-block is encoded or decoded using a modified predictor. The modified prediction is generated by clipping the prediction offset to a target range and combining the clipped prediction offset with an original predictor.

An apparatus having a processor and a circuit is disclosed. The processor may be configured to (i) compare, at a first level of a motion estimation hierarchy, first units of a current picture with a reference picture to generate first metrics, (ii) combine, at the first level, the first metrics to generate second metrics and (iii) refine, at a second level of the hierarchy, the first metrics and the second metrics to generate motion vectors. Multiple metrics may be refined in parallel. The first metrics generally correspond to the first units in an overlapping unit of the current picture. The second metrics generally correspond to a plurality of second units in the overlapping unit. Each second unit may overlap one or more first units. The circuit may be configured to process the overlapping unit based on the motion vectors to generate an output signal.

A video decoding method includes determining whether an ultimate motion vector expression (UMVE) mode is allowed for an upper data unit including a current block, when the UMVE mode is allowed for the upper data unit, determining whether the UMVE mode is applied to the current block, when the UMVE mode is applied to the current block, determining a base motion vector of the current block, determining a correction distance and a correction direction for correction of the base motion vector, determining a motion vector of the current block by correcting the base motion vector according to the correction distance and the correction direction, and reconstructing the current block based on the motion vector of the current block.

A method and apparatus for video coding. In some examples, an apparatus includes receiving circuitry and processing circuitry. The processing circuitry decodes prediction information of a block in a current picture from a coded video bitstream. The prediction information includes an index for prediction offset associated with an affine model in an inter prediction mode. The affine model is used to transform between the block and a reference block in a reference picture that has been reconstructed. Further, the processing circuitry determines parameters of the affine model based on the index and a pre-defined mapping of indexes and offset values, and reconstructs at least a sample of the block according to the affine model.

A method for processing a video includes performing a determination, by a processor, that a first video block is partitioned to include a first prediction portion that is non-rectangular and non-square; adding a first motion vector (MV) prediction candidate associated with the first prediction portion to a motion candidate list associated with the first video block, wherein the first MV prediction candidate is derived from a sub-block MV prediction candidate; and performing further processing of the first video block using the motion candidate list.