Abstract: At least a method and an apparatus are presented for efficiently encoding or decoding video. For example, the encoding or decoding comprises determining an intra prediction mode from a set of regular angular intra prediction modes and wide angular intra prediction modes wherein at least one of an angle or a reference array used by the angular intra prediction mode in the set are adapted to the width or the height of the image block which is not power of two. For example, the encoding or decoding comprises determining an intra sub-partition mode for an image block wherein at least one of a size or a number of intra sub-partitions in an intra sub-partition mode are adapted to the width or the height of the image block which is not power of two. Various embodiments are described for a ratio r used in an asymmetric split and p intra sub-partitions.

Abstract: In one implementation, when coding a block in the intra prediction mode, the block can be split into two sub-partitions by a geometrically located straight line. Each geometric partition within the CU is intra predicted using its own intra mode with its available reference sample. One sub-partition copies and uses the intra prediction mode from the parent block, and another sub-partition uses another implicit or explicit signaled intra prediction mode. After predicting geometric partition, the sample values along the split boundary are adjusted using a blending process with adaptive weights. The geometric partition based intra prediction could be applied for one angular intra prediction mode, or only for one negative-directional intra prediction mode, or only for one specific intra prediction mode (e.g., mode 34). The transform selection or other intra coding tools (i.e., intra sub-partition) can be adapted for the geometric partition based intra prediction.

Abstract: Video encoding and decoding using non-rectangular partitioning. An example video decoding method includes: obtaining information identifying a non-rectangular first partitioning of a current block into a plurality of prediction units; determining a second partitioning of the current block into a plurality of transform units, wherein each transform unit is completely spatially contained within a respective one of the prediction units; and decoding the current block according to the non-rectangular first partitioning and the second partitioning. In some embodiments, the scan order of the transform units is determined such that all transform units contained in a same one of the prediction units are scanned before starting to scan transform units that are contained in a different one of the prediction units.

Abstract: Asymmetric binary trees are used in combination with coding tools such as transform unit tiling, affine motion compensation, decoder side motion vector refinement, and bidirectional optical flow. In another embodiment asymmetric binary trees is used in combination with subblock temporal motion vector prediction. Embodiments enable tiling of coding blocks into subblocks in accordance with coding tools such as used in Versatile Video Coding.

Abstract: A method for video decoding is disclosed. A directional intra prediction mode is decoded for a block of a picture, the directional intra prediction mode having a direction. Based on the directional intra prediction mode, a first predictor and a second predictor for a sample in the current block are accessed, the first and second predictors being on a line at least approximating the direction. A sample value of the sample is predicted by interpolation using the first and second predictors, responsive to a difference between the second and first predictors, wherein the difference is scaled by at least a ratio that is based on a location of the sample in the block, and wherein a denominator of the ratio is a power of two regardless of the location of the sample. The sample of the block is reconstructed based on the predicted sample value.

Abstract: Video content frequently seen in gaming content and having a higher probability of being coded in transform skip mode is coded separately from remaining portions of a video coding block before being combined with regular coded portions. This enables more efficient coding of video by reducing the switching between regular coding modes and transform skip modes. The regular coded portion and the transform skip coded portion are combined in an encoder. At a corresponding decoder, inverse operations occur, such that the transform skipped residual portions are decoded and the regularly coded portions are decoded before the portions are combined for a resultant decoded video block.

Abstract: A method of performing intra prediction for encoding or decoding uses multiple layers of reference samples. The layers are formed into reference arrays that are used by a function, such as a weighted combination, to form a final prediction. The prediction is used in encoding or decoding a block of video data. The weights can be determined in a number of ways, and for a given prediction mode, the same weights, or different weights can be used for all pixels in a target block. If the weights are varied, they can depend on the distance of the target pixel from reference arrays.

Abstract: A method for video decoding is disclosed. A directional intra prediction mode is decoded for a block of a picture, the directional intra prediction mode having a direction. Based on the directional intra prediction mode, a first predictor and a second predictor for a sample in the current block are accessed, the first and second predictors being on a line at least approximating the direction. A sample value of the sample is predicted by interpolation using the first and second predictors, responsive to a difference between the second and first predictors, wherein the difference is scaled by at least a ratio that is based on a location of the sample in the block, and wherein a denominator of the ratio is a power of two regardless of the location of the sample. The sample of the block is reconstructed based on the predicted sample value.

Abstract: Methods and apparatus for intra prediction in video encoding and decoding using a composite reference array are described. In one exemplary embodiment, the composite reference array is formed from two or more reference arrays of a plurality of reference arrays. The composite reference array can be formed by projecting along a prediction direction, one or more of the plurality of reference arrays onto a reference array closest to the block of the video data being encoded or decoded. The filter coefficients for the interpolation filter are then determined based on the locations of the predictors on different reference arrays. Interpolating reference samples from different reference arrays, the predictor value for a target sample can be obtained.

Abstract: To encode a coding unit in the inter modes, there exist multiple inter modes that signal the motion information using a Motion Vector Predictor (MW) list. The MW lists for different coding modes include spatial predictors. In one embodiment, for all coding modes that use MVP lists, the top spatial predictor is first added to the motion vector predictor list before the left spatial predictor. In another embodiment, a subset of coding modes adds the top spatial predictor before the left spatial predictor, and another subset of coding modes adds the left spatial predictor before the top spatial predictor. For example, all merge modes add the top spatial predictor first, and all AMVP modes add the left spatial predictor first. In another example, all non-sub-block modes add the top spatial predictor first, and all sub-block modes add the left spatial predictor first.

Abstract: In video coding, a transform can be selected from multiple transform sets. To efficiently implement multiple transforms, a unified architecture of implementing the Discrete Trigonometric Transforms (DTTs) or flipped DTT can be used. In the proposed unified architecture, the relationships between the transforms are utilized. In particular, all transforms can be implemented based on DCT-II, DCT-IV, a reverse order operation, and a sign changing operation for odd elements. The DCT-II can be implemented at a minimum size, and other sizes for DCT-II can be implemented recursively from the minimum size DCT-II and DCT-IV at various sizes. In one example, the multiple transforms are {DCT-II, DST-II, DCT-III, DST-III, DCT-IV, DST-IV}. The relationships between transforms can also be used to guide the design of additional transforms that can be implemented by the unified architecture.

Abstract: At least one of the present embodiments generally relates to a method and an apparatus for video encoding and decoding, and more particularly, to a method and an apparatus for low-complexity bi-directional intra prediction. For example, a subset of a plurality of directional intra prediction modes is selected based on a shape of a current block of a picture being encoded or decoded. For a selected intra prediction mode in this subset, a sample value is bi-directionally intra predicted by using two predictors. The two predictors are substantially on a line based on a direction corresponding to the selected directional intra prediction mode. The bi-directional intra prediction may be only applied to large luma blocks, but not chroma blocks in order to reduce the computational complexity. When bi-directional intra prediction is used, the smoothing filtering may be omitted in intra prediction to further reduce the complexity.

Abstract: When a block is intra predicted, the predicted samples on the boundary are subject to boundary filtering for certain modes. Various embodiments are proposed to perform boundary filtering for intra prediction in the DC or PLANAR mode, using a gradient based approach. The gradient for a particular reference sample is calculated based on a difference between the particular reference sample and a predictor for predicting the particular reference sample. For the PLANAR mode, the difference between a top (left) reference sample and a linear interpolation using the top (left) reference samples is used as the gradient, a fractional part of which is propagated to the initial predicted samples with a decay function. For the DC mode, the difference between a top (left) reference sample and an average of reference samples is used as the gradient. The average can be computed with the top reference samples and/or left reference samples.

Abstract: A method for video decoding is disclosed. A directional intra prediction mode is decoded for a block of a picture, the directional intra prediction mode having a direction. Based on the directional intra prediction mode, a first predictor and a second predictor for a sample in the current block are accessed, the first and second predictors being on a line at least approximating the direction. A sample value of the sample is predicted by interpolation using the first and second predictors, responsive to a difference between the second and first predictors, wherein the difference is scaled by at least a ratio that is based on a location of the sample in the block, and wherein a denominator of the ratio is a power of two regardless of the location of the sample. The sample of the block is reconstructed based on the predicted sample value.

Abstract: Methods and apparatuses for intra prediction in video encoding and decoding using a blended intra predictor are described. In one exemplary embodiment, intra prediction is preformed using a blended intra predictor for a pixel of a current block being encoded and decoded. The blended intra predictor is determined by summing with corresponding weights a predictor using the intra prediction direction to be used for the current block and one or more predictors using the one or more corresponding intra prediction directions of the one or more neighboring blocks. The corresponding weights for the one or more neighboring blocks decrease with increased distance of the pixel to the one or more neighboring blocks.

Abstract: After initial intra prediction based on projection along an intra prediction direction, there may exist discontinuities between the predicted block and neighboring blocks. To smooth the block boundary, boundary filtering may be used with intra prediction. In particular, different methods may be used for boundary filtering. The particular filtering method to be used may be selected adaptively based on the intra prediction mode. When gradient-based filtering is selected, the gradient at a reference sample, that is at the same row or column as the current sample, in a reference layer is calculated as the difference between the reference sample and the predicted value for the reference sample using the intra prediction mode. Additional gradient at another reference sample from another reference layer may also be used. Then the initially predicted value for the sample may be adjusted based on the gradient(s) and a decay function.

Abstract: A method for video decoding is disclosed. A directional intra prediction mode is decoded for a block of a picture, the directional intra prediction mode having a direction. Based on the directional intra prediction mode, a first predictor and a second predictor for a sample in the current block are accessed, the first and second predictors being on a line at least approximating the direction. A sample value of the sample is predicted by interpolation using the first and second predictors, responsive to a difference between the second and first predictors, wherein the difference is scaled by at least a ratio that is based on a location of the sample in the block, and wherein a denominator of the ratio is a power of two regardless of the location of the sample. The sample of the block is reconstructed based on the predicted sample value.

Abstract: In general, encoding or decoding image information can involve processing a signal including image information based on determining a block of spatial-domain values for a prediction residual; replacing in a set of multiple transforms at least one first transform matrix with at least one second transform matrix and/or adding at least one second transform matrix to said set of multiple transforms; transforming the block of spatial-domain values using said second transform matrix; and encoding or decoding at least a portion of the image information based on the transforming of the block of spatial-domain values.

Abstract: When a block is intra predicted, the predicted samples on the boundary are subject to boundary filtering for certain modes. Various embodiments are proposed to perform boundary filtering for intra prediction in the DC or PLANAR mode, using a gradient based approach. The gradient for a particular reference sample is calculated based on a difference between the particular reference sample and a predictor for predicting the particular reference sample. For the PLANAR mode, the difference between a top (left) reference sample and a linear interpolation using the top (left) reference samples is used as the gradient, a fractional part of which is propagated to the initial predicted samples with a decay function. For the DC mode, the difference between a top (left) reference sample and an average of reference samples is used as the gradient. The average can be computed with the top reference samples and/or left reference samples.

Abstract: In video coding, a transform can be selected from multiple transform sets. To efficiently implement multiple transforms, a unified architecture of implementing the Discrete Trigonometric Transforms (DTTs) or flipped DTT can be used. In the proposed unified architecture, the relationships between the transforms are utilized. In particular, all transforms can be implemented based on DCT-II, DCT-IV, a reverse order operation, and a sign changing operation for odd elements. The DCT-II can be implemented at a minimum size, and other sizes for DCT-II can be implemented recursively from the minimum size DCT-II and DCT-IV at various sizes. In one example, the multiple transforms are {DCT-II, DST-II, DCT-III, DST-III, DCT-IV, DST-IV}. The relationships between transforms can also be used to guide the design of additional transforms that can be implemented by the unified architecture.