Abstract: A device includes processing circuitry configured to identify a set of pre-stored residual samples in video data that is stored to a memory, to combine the set of stored residual samples to form a combination, to apply a first sign combination to transform coefficients of the combination to obtain a first hypothesis reconstruction for a current block of the video data, and to apply a second sign combination to the transform coefficients of the combination to obtain a second hypothesis reconstruction for the current block. The processing circuitry is further configured to derive respective cost functions with respect to the first and second hypothesis reconstructions, to compare the respective derived cost functions, to select, based on the comparison, either the first or second hypothesis reconstruction, and to code the current block using a sign prediction associated with the selected one of the first or second hypothesis reconstruction.

Abstract: Techniques are described for improving transform coding. For example, an encoded block of video data can be obtained, and a width and/or a height of the block can be determined. The width can be compared to a first threshold and/or the height can be compared to a second threshold. A horizontal transform and a vertical transform can be determined for the block based on comparing the width of the block to the first threshold and/or the height of the block to the second threshold. The horizontal transform and the vertical transform are determined without decoding a syntax element that indicates the horizontal transform and the vertical transform (e.g., the syntax element is not in an encoded video bitstream processed by a decoding device). In some cases, residual data is determined using the horizontal and vertical transforms, and a video block is determined using the residual data and a predictive block.

Abstract: Techniques are described in which a decoder is configured to inverse quantize a first coefficient block and apply a first inverse transform to at least part of the inverse quantized first coefficient block to generate a second coefficient block. The first inverse transform is a non-separable transform. The decoder is further configured to apply a second inverse transform to the second coefficient block to generate a residual video block. The second inverse transform converts the second coefficient block from a frequency domain to a pixel domain. The decoder is further configured to form a decoded video block, wherein forming the decoded video block comprises summing the residual video block with one or more predictive blocks.

Abstract: A method and a device for decoding a video signal using an adaptive separable graph-based transform. The method includes: receiving a transform index for a target block from the video signal in which the transform index indicates a graph-based transform to be applied to the target block; deriving a graph-based transform kernel corresponding to the transform index; and decoding the target block based on the graph-based transform kernel. The device includes: a parsing unit configured to receive a transform index for a target block from the video signal; and an inverse-transform unit configured to derive a graph-based transform kernel corresponding to the transform index and decode the target block based on the graph-based transform kernel.

Abstract: A method of decoding video data comprises receiving a bitstream of encoded video data, the encoded video data representing partitioned luma blocks and partitioned chroma blocks, wherein the chroma blocks are partitioned independently of the luma blocks, determining a respective coding mode corresponding to the respective partitioned luma blocks, decoding the respective partitioned luma blocks according to the determined respective coding modes, decoding a first syntax element indicating that the respective coding modes associated with the respective partitioned luma blocks are to be used for decoding a first partitioned chroma block, wherein the first partitioned chroma block is aligned with two or more partitioned luma blocks, determining a chroma coding mode for the first partitioned chroma block according to a function of the respective coding modes of the two or more partitioned luma blocks, and decoding the first partitioned chroma block in accordance with the determined chroma coding mode.

Abstract: For at least one respective bin of the bin stream, a decoder may determine, based on a state for the respective bin, an interval for the respective bin, and the offset value, a value of the respective bin. Additionally, the decoder determines one or more Finite State Machine (FSM) parameters for a next bin of the bin stream. The one or more FSM parameters for the next bin controls how probability estimates for the next bin are computed from a state for the respective bin. The decoder determines using a parameterized state updating function that takes as input the state for the respective bin, the one or more FSM parameters for the next bin of the bin stream, and the value of the respective bin, a state for the next bin of the bin stream. The decoder may debinarize the bin stream to form a decoded syntax element.

Abstract: A device for coding video data is configured to determine that a current block of video data is coded using an intra prediction mode; add an intra prediction mode of a first neighboring block of the current block to a most probable mode candidate list for the current block; add an intra prediction mode for a second neighboring block of the current block to the most probable mode candidate list for the current block; add an intra prediction mode for a third neighboring block of the current block to the most probable mode candidate list for the current block; and code the current block of video data using an intra prediction mode.

Abstract: This disclosure describes examples of extending the number of available discrete cosine transform (DCT) and discrete sine transform (DST) for encoding and decoding. A video coder may determine one or more transforms or inverse transforms to apply from a set of transforms or inverse transforms that includes DCT-2 or inverse DCT-2, DST-7 or inverse DST-7, DST-8 or inverse DST-8, DCT-3 or inverse DCT-3, DST-2 or inverse DST-2, DST-3 or inverse DST-3, DCT-4 or inverse DCT-4, DST-4 or inverse DST-4, DST-5 or inverse DST-5, DST-6 or inverse DST-6, and identity transform an inverse identity transform (IDT).

Abstract: An example coding device, such as a video coding (encoding or decoding) device is configured to determine a plurality of estimator functions to be used to calculate a probability of a symbol having a particular value, wherein the symbol is to be binary arithmetic coded according to the probability, and wherein the estimator functions do not include division operations; determine a plurality of weights for the plurality of estimator functions such that when the respective weights are applied to the estimator functions, a resulting sum of outputs of the plurality of estimator functions yields the probability; calculate the probability of the symbol having the particular value, including: execute the estimator functions without using the division operations to determine the outputs; and calculate a sum of the outputs as the probability; and binary arithmetic code the symbol according to the probability of the symbol having the particular value.

Abstract: Techniques are described to improved video intra prediction using position-dependent prediction combination in video coding. In High Efficiency Video Encoding a set of 35 linear predictors are used for doing intra coding and prediction can be computed from either a nonfiltered or a filtered set of neighboring “reference” pixels, depending on the selected predictor mode and block size. Techniques of this disclosure may use a weighted combination of both the nonfiltered and filtered set of reference pixels to achieve better compression via improved prediction and therefore small residual, enable effective parallel computation of all sets of prediction values, and maintain low complexity via applying filtering only to a set of reference pixels and not to predicted values themselves.

Abstract: An example device for decoding video data includes a memory configured to store video data; and a processor implemented in circuitry and configured to decode a truncated unary codeword representing a multiple transform (MT) scheme for a current block of the video data to determine the MT scheme; apply the MT scheme to transform coefficients of the current block to produce residual data for the current block of video data; and decode the current block using the residual data. The MT scheme may include a plurality of transforms, such as a horizontal transform and a vertical transform, a primary transform and a second transform, or any combination of separable and/or non-separable transforms. Thus, a single truncated unary codeword may represent the entire MT scheme, that is, each of a plurality of transforms of the MT scheme.

Abstract: A method of decoding video data including receiving video data including coded representations of syntax elements performing inverse binary arithmetic coding on the coded representations of the syntax elements to obtain bins of the syntax elements, inverse binarizing the bins of the syntax elements to obtain the syntax elements, and decoding the video data based on the syntax elements. Performing the inverse binary arithmetic coding includes determining a probability for a particular coded representation of the coded representations, normalizing the probability for the particular coded representation using right bit shifts to create a normalized probability, determining a product of the normalized probability and a range for the particular coded representation, and updating a range of a least probable symbol for the particular coded representation using the determined product.

Abstract: Techniques are described in which a decoder is configured to inverse quantize a first coefficient block and apply a first inverse transform to at least part of the inverse quantized first coefficient block to generate a second coefficient block. The first inverse transform is a non-separable transform. The decoder is further configured to apply a second inverse transform to the second coefficient block to generate a residual video block. The second inverse transform converts the second coefficient block from a frequency domain to a pixel domain. The decoder is further configured to form a decoded video block, wherein forming the decoded video block comprises summing the residual video block with one or more predictive blocks.

Abstract: Disclosed herein is a method of encoding a video signal, comprising receiving an original video signal; comparing the original video signal with available reconstructed signals; determining a correction signal based on a result of the comparison; and generating a transform-coded correction signal to be transmitted for a signal reconstruction.

Abstract: Disclosed is a method for encoding a video signal using parallel implementations, including generating data symbols to be encoded, encoding 1st data symbols being in a base segment, copying 2nd data symbols being in another segment to a buffer, and encoding in parallel the 2nd data symbols being in the another segment.

Abstract: Disclosed herein is a method of performing an arithmetic decoding for data symbols, comprising: creating a decoding table index; obtaining an upper bound value and a lower bound value of a ratio between an interval length and a point within an interval assigned to a symbol from a ROM table; obtaining initial values for a bisection search from a RAM table based on the upper bound value and the lower bound value; and searching a value of sequence in the interval, wherein the interval is determined based on the initial values.

Abstract: A method of decoding video data comprising receiving a block of video data encoded using a position dependent intra prediction combination (PDPC) mode, the block of video data having a non-square shape defined by a width and a height, determining one or more PDPC parameters based on one or more of the width or the height of the block of video data, and decoding the block of video data using the PDPC mode and the determined PDPC parameters.

Abstract: An example method of decoding video data includes determining, by a video decoder and based on syntax elements in an encoded video bitstream, a plurality of values for a current block of the video data; performing, by the video decoder, a multi-pass non-separable inverse transformation on the plurality of values to derive residual data that represents pixel differences between the current block of the video data and a predictive block of the video data; and reconstructing, by the video decoder, the current block of the video data based on the residual data and the predictive block of the video data. In some examples, performing a pass of the multi-pass non-separable inverse transformation includes performing a plurality of Givens orthogonal transformations.

Abstract: Techniques are described of using Position Dependent Intra Prediction Combination (PDPC). A video coder such as a video encoder or a video decoder utilizes PDPC in cases where a current block intra mode predicted using an angular intra prediction mode.

Abstract: A device may perform a first prediction process for a first block of video data to produce a first residual. The device may apply a first transform process to the first residual to generate first transform coefficients for the first block of video data and encode the first transform coefficients. The device may perform a second prediction process for a second block of video data to produce a second residual. The device may determine that a second transform process, which includes the first transform process and at least one of a pre-adjustment operation or a post-adjustment operation, is to be applied to the second residual. The device may apply the first transform process and the pre- or post-adjustment operation to the second residual to generate second transform coefficients for the second block. The coding device may code the first and second transform coefficients.