Abstract: A feature value is determined based on at least one of (i) neighboring reconstructed chroma samples of a current chroma block and (ii) neighboring reconstructed luma samples of a luma block that is collocated with the current chroma block. Chroma samples of the current chroma block and luma samples of the luma block that is collocated with the current chroma block are grouped into a plurality of groups based on a threshold of the feature value. Each of the plurality of groups includes a respective chroma sample and a respective luma sample. A respective cross-component prediction mode is determined for each of the plurality of groups by comparing the respective chroma sample and the respective luma sample of each respective group to the determined feature value. The current chroma block is reconstructed based on the determined cross-component prediction modes of the plurality of groups.

Abstract: Low complexity, hardware-friendly techniques are proposed for video coding systems to mitigate banding artifacts while maintaining the compression efficiency. In general, the proposed techniques consist of two stages including a banding detection stage and a de-banding stage. The banding detection stage may identify the image/video regions where the banding artifact may be present based on gradient information and other information. The de-banding stage may apply corrective techniques to regions identified as likely to possess banding artifacts. In one embodiment, the de-banding adapts the filtering logic proposed by prior video coding standards for other filtering applications to mitigate banding. When implemented over the AV1 video coding standard and the AOM Video Model (AVM) reference software, the proposed technique improves subjective quality significantly at a reasonable hardware implementation cost.

Abstract: Aspects of the disclosure provide methods and apparatuses for video coding. In some examples, an apparatus includes processing circuitry. The processing circuitry obtains prediction information of a first block in a picture from a coded video bitstream, and generates reconstructed samples of the first block according to the prediction information and one of bi-directional prediction and uni-directional prediction. The processing circuitry adds motion information and a bi-prediction weight index of a History-based Motion Vector Prediction (HMVP) candidate to an HMVP list based on the prediction information of the first block and whether the first block is coded according to the bi-directional prediction or the uni-directional prediction. Further, the processing circuitry generates reconstructed samples of a second block in the picture based on a plurality of candidates that includes the HMVP candidate.

Abstract: A coded video bitstream comprising a current block in a current picture is received. The current block includes a plurality of subblocks and is to be predicted by a subblock-based template matching motion vector prediction (SbTMVP) mode. A respective collocated reference subblock for each subblock is determined based on a combination of a displacement vector (DV) and a motion vector offset (MVO) that are associated with the respective subblock. A motion vector (MV) field in the respective collocated reference subblock of each subblock in the current block is determined. A respective reference template for each subblock is derived based on the determined MV field of the collocated reference subblock. The plurality of subblocks of the current block is reconstructed by predicting each subblock using the respective reference template in the SbTMVP mode.

Abstract: Aspects of the disclosure provide methods and apparatuses for video coding. In some examples, an apparatus includes processing circuitry configured to encode a first block in a picture according to one of bi-directional prediction and uni-directional prediction. The processing circuitry is configured to add motion information and a bi-prediction weight index of a History-based Motion Vector Prediction (HMVP) candidate to an HMVP list based on whether the first block is encoded according to the bi-directional prediction or the uni-directional prediction, the bi-prediction weight index indicating bi-prediction weights of the bi-directional prediction for the first block when the first block is encoded according to the bi-directional prediction, and the bi-prediction weight index indicating a default value when the first block is encoded according to the uni-directional prediction.

Abstract: Aspects of the disclosure provide a method and an apparatus including processing circuitry that decodes a current block in a current picture with a subblock-based temporal motion vector prediction (SbTMVP) mode. A first collocated block in a first collocated picture is determined based on a first displacement vector candidate of the current block corresponding to a first SbTMVP candidate. The processing circuitry determines first motion information of a current template of the current block based on one or more pieces of motion information of the first collocated block or a neighboring block of the first collocated block. The processing circuitry determines one of a first reference template and a first subblock reference template in a first reference picture based on the first motion information and determines a first template matching cost based on the current template and the one of the first reference template and the first subblock reference template.

Abstract: Aspects of the disclosure provide a method and an apparatus for video decoding. The apparatus includes processing circuitry. The processing circuitry applies an intra prediction mode with a multiple reference line (MRL) prediction to a current block. For each weight candidate combination including a respective first weight candidate and a respective second weight candidate in a plurality of weight candidate combinations, a subset of samples in the current block is predicted using intra prediction fusion that is based on a first reference line weighted by the respective first weight candidate and a second reference line weighted by the respective second weight candidate. The subset of samples includes top samples in a top-most row and left samples in a left-most column. A gradient cost is determined based on the predicted subset of samples and reconstructed samples outside the current block. A weight candidate combination is selected based on the gradient costs.

Abstract: A method for video encoding includes determining that a current block in a first coding tree unit (CTU) of a current picture is to be coded using an affine model in a merge mode, and obtaining, from a line buffer, one or more motion vectors of blocks located at bottom locations in a second CTU above the current block. The line buffer only stores motion vectors of minimum-size blocks located at the bottom locations of the second CTU above the current block and the line buffer does not store (i) a block width or block height of the minimum-size blocks, (ii) affine control point information, and (iii) an affine flag. The method further includes deriving motion vectors of control points of the current block using the affine merge model, and encoding the current block based on the affine merge model and the motion vectors of the control points.

Abstract: Aspects of the disclosure provide methods and apparatuses for video decoding. In some examples, an apparatus includes processing circuitry. The processing circuitry decodes prediction information of a current block from a coded video bitstream. Based on an intra block copy mode being applied to the current block, the processing circuitry infers a vector resolution flag indicates that a resolution of a block vector is integer-pel, determines the resolution of the block vector based on resolution information that is included in the prediction information, determines the block vector according to the determined resolution, and reconstructs at least one sample of the current block according the block vector.

Abstract: An apparatus for video encoding includes processing circuitry that is configured to decode partition information from a coded video bitstream. The partition information is indicative of a minimum allowed QT leaf node size for a I slice. The minimum allowed QT leaf node size for the I slice is constrained by a threshold that is lower than a CTU size. The processing circuitry is configured to determine, based on an override enabling flag, the minimum allowed QT leaf node size according to one of a first syntax element in an SPS or a second syntax element in a PH included in the partition information. The processing circuitry is configured to partition a coding tree block in the I slice into coding blocks based on the determined minimum allowed QT leaf node size. The processing circuitry is configured to reconstruct the coding blocks respectively from the coded video bitstream.

Abstract: Aspects of the disclosure provide a method and an apparatus including processing circuitry that determines, based on a syntax element in a coded video bitstream, that a current block including a plurality of subblocks is coded in a subblock-based temporal motion vector prediction (SbTMVP) mode. Motion vector offset (MVO) information indicating an MVO is received. The MVO indicates a motion offset of a displacement vector (DV) used to adjust a location of a collocated block in a collocated reference picture. An updated DV of the current block is determined based on the DV and the MVO. SbTMVP information of a respective subblock in the plurality of subblocks is derived based on motion information of a corresponding subblock in the collocated block indicated by the updated DV. The plurality of subblocks in the SbTMVP mode is reconstructed based on the SbTMVP information of the subblock in the plurality of subblocks.

Abstract: In a method of video encoding, a corresponding block of a current block in a current picture is determined based on an offset vector that indicates an offset between the current block and the corresponding block. The current block includes a plurality of subblocks to be encoded in a subblock-based frame-rate up conversion (FRUC) mode. A temporal motion vector predictor (TMVP) of a first subblock in the corresponding block is determined based on a subblock in a forward reference picture of the current picture and a subblock in a backward reference picture of the current picture. The subblocks in the forward reference picture and the backward reference picture are matched using the subblock-based FRUC mode. Based on the TMVP, a TMVP of a subblock is determined in the plurality of subblocks in the current block.

Abstract: A method performed by a video decoder includes receiving a coded video bitstream including a current picture that includes at least one block. The method includes determining that the at least one block is to be predicted in a reconstruction-reordered intra block copy (RR-IBC) mode. The method includes obtaining a syntax element from the at least one block, the syntax element indicating a flip mode. The method includes determining whether reconstruction flip is applied to the at least one block. The method includes, in response to determining the reconstruction flip is applied to the at least one block, predicting a flip pattern for the at least one block based on neighboring reconstruction samples of the at least block and a corresponding reference block of the at least one block. The method further includes decoding the at least one block based on the flip mode and the predicted flip pattern.

Abstract: Processing circuitry decodes, from a bitstream carrying a video including a current picture, a signal indicative of a subblock based intra block copy (IBC) merge mode for predicting a current block in the current picture. The processing circuitry determines a predictor offset (also referred to as offset BV) associated with the current block. The predictor offset indicates a predictor block in the current picture corresponding to the current block, the predictor block includes a plurality of predictor subblocks respectively corresponding to a plurality of subblocks in the current block. The processing circuitry determines a first block vector of a first subblock according to a first predictor block vector associated with a first predictor subblock. The processing circuitry reconstructs the first subblock in the current block according to the first block vector that points to a reference block for the first subblock in the current picture.

Abstract: In a method, whether a subregion of a current picture includes a fading region that transitions from a first scene to a second scene is determined during a pre-analysis stage. The subregion of the current picture includes one or more coding units (CUs). Whether a bi-prediction with CU-level weight (BCW) mode is applied to the subregion of the current picture at a block level is determined based on whether the subregion of the current picture is determined to include the fading region. An inter prediction is performed on the subregion of the current picture based on whether the subregion is determined to include the fading region and whether the BCW mode is determined to be applied to the subregion of the current picture at the block level.

Abstract: An apparatus for video decoding includes processing circuitry. The processing circuitry can be configured to determine an intermediate motion vector MVblock of a current block having a first precision that is higher than a second precision supported by an interpolation filter. The processing circuitry can be configured to round the intermediate motion vector MVblock to generate a rounded motion vector MVround of the current block having the second precision supported by the interpolation filter. The processing circuitry can be configured to generate a prediction block of the current block based on the rounded motion vector MVround and the interpolation filter. The processing circuitry can be configured to determine a prediction refinement offset for a prediction sample of the prediction block, and add the prediction refinement offset to the prediction sample of the prediction block to generate a refined prediction sample.

Abstract: Processing circuitry receives a coded bitstream carrying at least a picture, determines that a current coding unit (CU) in the picture is coded in a subblock based inter prediction mode based on a first syntax element value in the coded bitstream, and determines that one or more first subblocks in the current CU that is coded in the subblock based inter prediction mode are coded by intra prediction. The processing circuitry reconstructs one or more second subblocks of the current CU by inter prediction based on the subblock based inter prediction mode, the one or more second subblocks do not overlap with the one or more first subblocks in the current CU. The processing circuitry reconstructs the one or more first subblocks of the current CU by the intra prediction while the current CU is coded in the subblock based inter prediction mode.

Abstract: A feature value is determined based on at least one of (i) neighboring reconstructed chroma samples of a current chroma block and (ii) neighboring reconstructed luma samples of a luma block that is collocated with the current chroma block. Chroma samples of the current chroma block and luma samples of the luma block that is collocated with the current chroma block are grouped into a plurality of groups based on a threshold of the feature value. Each of the plurality of groups includes a respective chroma sample and a respective luma sample. A respective cross-component prediction mode is determined for each of the plurality of groups by comparing the respective chroma sample and the respective luma sample of each respective group to the determined feature value. The current chroma block is reconstructed based on the determined cross-component prediction modes of the plurality of groups.

Abstract: A method includes receiving a coded video bitstream that includes a current picture with at least one block located at a boundary of the current picture and coded in accordance with an intra template matching (intraTMP) mode; determining boundary filtering is enabled for the at least one block based on a syntax element in the received coded video stream; filtering one or more boundary samples corresponding to the at least one block to generate one or more filtered samples; and decoding the at least one block based on the generated one or more filtered samples.

Abstract: In a method for video coding in a decoder, prediction information of a current block of a current picture in a coded bitstream is decoded. The prediction information indicates a geometric partitioning mode (GPM) for the current block. The current block is partitioned into two partitions in the GPM mode, and each of the partitions is associated with a respective predictor. A weighting index for a sample of the current block is determined based on a position of the sample. A weighting factor is calculated based on the weighting index of the sample according to an equation that converts the weighting index to the weighting factor. The calculation includes performing a right shift operation based at least on a sum of the weighting index and an offset value, and clipping a result of the right shift operation to be within a predefined range. The sample is reconstructed based on the weighting factor and the predictor corresponding to the sample.