Abstract: Techniques are proposed to improve temporal motion projection in video coding. Candidate reference frames available for use in temporal motion projection are sorted in processing order according to scores assigned based on estimates of the reference frames' suitability for prediction. Such estimates may be based on temporal distance between each candidate reference frame and that reference frame's prediction references. Estimates may be based, for each reference frame, based on an estimate of coding quality of a reference frame from which the respective candidate reference frame makes a prediction reference. Once sorted, the candidate reference frames may be processing in the sorting order to supply prediction data to a current frame that is to be coded from the candidate reference frames. Additionally, hardware friendly designs of motion field hole filling and motion vector smoothing operations are proposed.

Abstract: A method, computer program, and computer system is provided for coding video data. Video data is received, and an edge present within a sample of the received video data is detected. A gradient value corresponding to a direction associated with the detected edge is calculated. The video data is decoded based on the calculated gradient.

Abstract: A method of loop filtering in a video coding process comprises receiving image data; analyzing the image data; flexibility partitioning the image data into loop filtering blocks (LFBs) to allow the size of LFBs in at least one of a first row and a first column in a same frame to be smaller than other LFBs within the same frame; and applying a loop filter to the LFBs.

Abstract: An apparatus for video decoding including processing circuitry is provided. The processing circuitry is configured to receive a bitstream that includes coded information indicating a filter shape of a sample offset filter to be applied to a reconstructed sample of a first component in a current picture, the filter shape of the sample offset filter being one of a plurality of filter shapes, each of the plurality of filter shapes including different first reconstructed samples of a second component in the current picture. The processing circuitry is configured to determine an output value of the sample offset filter based on the first reconstructed samples in the filter shape indicated by the coded information. The processing circuitry is configured to determine a filtered sample value of the reconstructed sample of the first component based on the reconstructed sample and the output value of the sample offset filter.

Abstract: In an example method, a decoder accesses a bitstream representing video content, and parses one or more flexible coefficient position (FCP) syntax from the bitstream, where the one or more FCP syntax indicate one or more index values. The decoder further determines side information representing one or more characteristics of an encoded portion of the video content. The decoder interprets the one or more FCP syntax based on the side information, including determining a coefficient position with respect to the encoded portion of the video content based on the one or more index values and the side information. The decoder decodes the encoded portion of the video content according to the coefficient position.

Abstract: A method for filtering includes determining, by a processor, a first offset value by applying a non linear mapping based filter to first reconstructed samples at a first node along a loop filter chain that includes a plurality of video filters. The method further includes applying, by the processor, the first offset value to an intermediate reconstructed sample at a second node along the loop filter chain to generate a second reconstructed sample, wherein the second node is one of an input node of the loop filter chain or an output node of the loop filter chain.

Abstract: Aspects of the disclosure include methods, apparatuses, and non-transitory computer-readable storage mediums for video encoding/decoding. An apparatus includes processing circuitry that determines reconstructed samples of a first color component in a filter support region of a current picture that is a part of a coded video sequence. The processing circuitry performs a filter process on the reconstructed samples of the first color component in the filter support region. A quantization step size of the filter process is separately set per one of a coding block, a video frame, and a video sequence. The processing circuitry reconstructs samples of a second color component in the filter support region based on an output value of the filter process. The second color component is different from the first color component.

Abstract: In a method, a filter shape is determined from a plurality of filter shapes of a sample offset filter to be applied to a reconstructed sample of a current component in a current picture. A coded video bitstream is generated based on samples of the current picture and the determined filter shape of the sample offset filter. The coded video bitstream includes coded information that indicates the filter shape. A top most sample of the first reconstructed samples in the plurality of filter shapes is located within a first predetermined number of top rows above a center reconstructed sample of the first component that is co-located with the reconstructed sample of the current component. A bottom most sample of the first reconstructed samples in the plurality of filter shapes is located within a second predetermined number of bottom rows below the center reconstructed sample of the first component.

Abstract: The present disclosure describes techniques for efficient coding of motion vectors developed for multi-hypothesis coding applications. According to these techniques, when coding hypotheses are developed, each having a motion vector identifying a source of prediction for a current pixel block, a motion vector for a first one of the coding hypotheses may be predicted from the motion vector of a second coding hypothesis. The first motion vector may be represented by coding a motion vector residual, which represents a difference between the developed motion vector for the first coding hypothesis and the predicted motion vector for the first coding hypothesis, and outputting the coded residual to a channel. In another embodiment, a motion vector residual may be generated for a motion vector of a first coding hypothesis, and the first motion vector and the motion vector residual may be used to predict a second motion vector and a predicted motion vector residual.

Abstract: A method of video decoding includes determining reconstructed samples of a first color component in a filter support region of a current picture that is a part of a coded video sequence, and performing a cross-component sample offset (CCSO) filter process on the reconstructed samples of the first color component in the filter support region to generate an output offset value. The method also includes scaling the output offset value based on the reconstructed samples of the first color component in the filter support region, and reconstructing samples of a second color component in the filter support region based on the scaled output offset value. The second color component is different from the first color component.

Abstract: In a method for filtering in video coding, first boundary pixel values of a subset of first reconstructed samples are buffered at a first node in a loop filter chain, a first filter and a second filter being applied to the first boundary pixel values, the first boundary pixel values being values of pixels at a frame boundary. Second boundary pixel values of a subset of second reconstructed samples are buffered at a second node in the loop filter chain, the second boundary pixel values being values of the pixels at the frame boundary. A loop restoration filter is applied on to-be filtered reconstructed samples based on the buffered first boundary pixel values of the subset of the first reconstructed samples and the buffered second boundary pixel values of the subset of the second reconstructed samples.

Abstract: A method for video encoding includes determining a filter shape of a cross-component filter applied to a chroma coding block (CB), generating a first intermediate CB by applying a loop filter to the chroma CB, and generating a second intermediate CB by applying, to a corresponding luma CB, the cross-component filter applied to the chroma CB and having the determined filter shape. The method further includes determining a filtered chroma CB based on the first intermediate CB and the second intermediate CB by combining the loop filtered chroma CB with the cross-component filtered luma CB, and generating coded information of the chroma CB in a coded video bitstream. Determining the filter shape includes determining the filter shape of the cross-component filter based on the number of the filter coefficients and based on at least one of (i) the chroma subsampling format or (ii) the chroma sample type.

Abstract: Improved lossless entropy coding techniques for coding of image data include selecting a context for entropy coding based on an ordered scan path of possible context locations. A symbol for a current location within a source image may be entropy coded based on a context of prior encoded symbols of other locations within source images, where the context is selected based on an ordered scan path enumerating a series of potential context locations within one or more source images. To select a context, a predetermined number of prior symbols may be selected by qualifying or disqualifying locations in the scan path, and then the current symbol may be encoded with a context based on prior symbols corresponding to the first qualifying context locations in the order of the scan path.

Abstract: A method of video coding, executable by a processor, includes receiving video data having a coding tree unit size, determining whether the coding tree unit size is greater than a predetermined threshold, and in response to the coding tree unit size being greater than the predetermined threshold, signaling, in a sequence parameter set (SPS), a first flag indicating whether a maximum transform size in luma samples is equal to 64. The first flag being equal to 1 specifies that the maximum transform size in luma samples is equal to 64, the first flag equal to 0 specifies that the maximum transform size in luma samples is equal to 32, and when not present, the first flag is inferred to be equal to 0.

Abstract: An apparatus for video coding is provided. The apparatus includes processing circuitry that buffers first boundary pixel values of first reconstructed samples at a first node along a loop filter chain. The first node is associated with a non linear mapping based filter that is applied in the loop filter chain before a loop restoration filter. The first boundary pixel values are values of pixels at a frame boundary. The processing circuitry applies the loop restoration filter on to-be filtered reconstructed samples based on the buffered first boundary pixel values.

Abstract: Techniques are disclosed for improved video coding with virtual reference frames. A motion vector for prediction of a pixel block from a reference may be constrained based on the reference. In as aspect, if the reference is a temporally interpolated virtual reference frame with corresponding time close to the time of the current pixel block, the motion vector for prediction may be constrained magnitude and/or precision. In another aspect, a bitstream syntax for encoding the constrained motion vector may also be constrained. In this manner, the techniques proposed herein contribute to improved coding efficiencies.

Abstract: An image processing method includes obtaining statistics information of a block of an image frame, determining whether the statistics information satisfies a condition, and disabling cross-component filtering (CCF) for the block in response to the statistics information satisfying the condition.

Abstract: Disclosed is a method that includes receiving an image frame having a plurality of coded blocks, determining a prediction unit (PU) from the plurality of coded blocks, determining one or more motion compensation units arranged in an array within the PU, and applying a filter to one or more boundaries of the one or more motion compensation units. Also disclosed is a method that includes receiving a reference frame that includes a reference block, determining a timing for deblocking a current block, performing motion compensation on the reference frame to obtain a predicted frame that includes a predicted block, performing reconstruction on the predicted frame to obtain a reconstructed frame that includes a reconstructed PU, and applying, at the timing for deblocking the current block, a deblocking filter based on one or more parameters to the reference block, the predicted block, or the reconstructed PU.

Abstract: A method for video encoding includes determining a filter shape of a cross-component filter applied to a chroma coding block (CB), generating a first intermediate CB by applying a loop filter to the chroma CB, and generating a second intermediate CB by applying, to a corresponding luma CB, the cross-component filter applied to the chroma CB and having the determined filter shape. The method further includes determining a filtered chroma CB based on the first intermediate CB and the second intermediate CB by combining the loop filtered chroma CB with the cross-component filtered luma CB, and generating coded information of the chroma CB in a coded video bitstream. Determining the filter shape includes determining the filter shape of the cross-component filter based on the number of the filter coefficients and based on at least one of (i) the chroma subsampling format or (ii) the chroma sample type.

Abstract: A flexible coefficient coding (FCC) approach is presented. In the first aspect, spatial sub-regions are defined over a transform unit (TU) or a prediction unit (PU). These sub-regions organize the coefficient samples residing inside a TU or a PU into variable coefficient groups (VCGs). Each VCG corresponds to a sub-region inside a larger TU or PU. The shape of VCGs or the boundaries between different VCGs may be irregular, determined based on the relative distance of coefficient samples with respect to each other. Alternatively, the VCG regions may be defined according to scan ordering within a TU. Each VCG can encode a 1) different number of symbols for a given syntax element, or a 2) different number of syntax elements within the same TU or PU. Whether to code more symbols or more syntax elements may depend on the type of arithmetic coding engine used in a particular coding specification. For multi-symbol arithmetic coding (MS-AC), a VCG may encode a different number of symbols for a syntax element.