Abstract: When dependent scalar quantization is used, the choice of the quantizer depends on the decoding of the preceding transform coefficient, and the entropy decoding of a transform coefficient depends on quantizer choice. To maintain high throughput in hardware implementations for transform coefficient entropy coding, several decision schemes of the scaler quantizer are proposed. In one implementation, the state transition and the context model selection are based on only regular coded bins. For example, the state transition can be based on the sum of the SIG, gt1 and gt2 flags, the exclusive-or function of the SIG, gt1 and gt2 flags, or based on only the gt1 or gt2 flag. When a block of transform coefficients is coded, the regular mode bins can be coded first in one or more scan passes, and the remaining bypass coded bins are grouped together in another one or more scan passes.

Abstract: A coding unit having a size multiple of three in horizontal or vertical direction is coded through one of several embodiments. In one embodiment, for some block sizes, the coding unit is coded and decoded systematically through SKIP mode. In another embodiment, the coding units can be coded in SKIP mode or with a DC coefficient. In another embodiment, an asymmetric division of a common coding unit parent is performed and transform coefficients are factorized among at least two sub-blocks to encode a coding unit. In another embodiment, a separable two dimensional transform can be applied by applying a transform over the block in one direction, and using two one-dimensional transforms on sub-blocks in the other direction to code. Methods, apparatus, and signal embodiments are provided for encoding and decoding.

Abstract: An encoding method is disclosed. At least one context is first determined for encoding a syntax element associated with a block of a picture responsive to a current quantization parameter associated with the block. Second, the syntax element is context-based entropy encoded with the at least one determined context.

Abstract: The present principles relates to a method for encoding an image unit comprising image data represented by a luminance channel and at least one chrominance channel, the method comprising obtaining a luma coding-tree by splitting a luminance unit representative of the luminance channel of said image unit and obtaining a chroma coding-tree by splitting a chrominance unit representative of at least one chrominance channel of said image unit. The method is characterized in that obtaining said chroma coding-tree comprises: —determining whether said chroma coding-tree and said luma coding-tree are identical; and —signaling an information data indicating whether said chroma coding-tree and said luma coding-tree are identical.

Abstract: The present principles relates to a method and device 1. A method for encoding a residual block comprising: —obtaining (500) a first coding mode relative to a first 2D transform when coding the residual blocks according a coding mode relative to a first 2D transform is enabled; —obtaining (510) a second coding mode relative to a second 2D transform when coding the residual blocks according to a coding mode relative to a second 2D transform is enabled; and —encoding (530) the residual block according to either said first coding mode or said second coding mode or both; the method is characterized in that enabling or disabling (520) the coding of the residual block according to said second coding mode depends on said first coding mode. The present principles relates also to a method and device for encoding/decoding a picture.

Abstract: Different implementations are described; particularly implementations for video encoding and decoding using merge lists comprising history-based motion vector predictor candidates and averaged motion vector predictor candidates. The method comprises: determining for a current block of the picture one or more history-based motion vector predictor candidates using motion information of blocks preceding the current block; determining for the current block one or more averaged motion vector predictor candidates by averaging a pair of motion vector predictor candidates in a list of motion vector predictor candidates, wherein the motion vector predictor candidates in the list are formed using motion information of blocks spatially and/or temporally surrounding the current block; and inserting one or more of the averaged motion vector predictor candidates before one or more of the history-based motion vector predictor candidates in the list of motion vector predictor candidates.

Abstract: A block of video data is split using at least one splitting rule and coded using existing transform sizes through one of several embodiments. In one embodiment, the block is split using a triple tree splitting operation if said at least two rectangular sub-blocks can be achieved with two successions of split operations with at least one triple tree split. In another embodiment, the video block is split using an asymmetric binary tree splitting if said at least two rectangular sub-blocks can be achieved with two successions of split operations with at least one asymmetric binary split. In another embodiment, a video block is split using successive splits, using both of the rules of the other embodiments.

Abstract: Different implementations are described, particularly implementations for video encoding and decoding based on asymmetric binary partitioning of image blocks are presented. The encoding method comprises for a picture, wherein at least one component of the picture is divided into blocks of samples, partitioning a block into block partitions, wherein at least one block partition has a size equal to a positive integer different from a power of 2 in width and/or height, obtaining a residual based on a difference between a prediction of the block partitions and the block partitions, splitting the residual into at least two residual blocks with a size equal to a power of 2 in width and height and encoding the at least two residual blocks. Ohers embodiments are presented for a block partitioning on the border of the picture, for setting maximum and/or minimum block sizes and for corresponding decoding method.

Abstract: A video codec can involve processing video information based on a motion model involving a coding unit including a plurality of sub-blocks, such as an affine motion model, to produce motion compensation information, obtaining a local illumination compensation model, and encoding or decoding the video information based on the motion compensation information and the local illumination compensation model.

Abstract: A method and an apparatus for coding a video are disclosed. At least one transform subblock in a block of a picture of the video is determined (1600) depending on a shape of the block and the block is coded (1630) based at least on the determined transform subblock. Corresponding decoding method and apparatus are disclosed.

Abstract: A method and apparatus adapts motion vector prediction for suitability to omnidirectional video. One embodiment improves handling of temporal motion vector predictors or rescaled motion vector predictors. Another embodiment is suited to spatial motion vector predictors, and another to a combination of either temporal or spatial motion vector predictors. The method analyzes a scale factor derived from, at least one of, the time index of the predictor, the time index of the reference image's predictor, the time index of a reference image's current block, and the time index of the current block. If, for example, the scale factor is greater than one, motion vector transformation is performed before motion vector rescaling. If, however, the scale factor is less than or equal to one, the motion vector rescaling is performed before motion vector transformation.

Abstract: A video encoder or decoder processes portions of video using virtual temporal affine motion candidates. Under the general aspects, virtual temporal affine candidates are created using only the classical temporal motion buffer information, avoiding the storage of additional affine parameters in a temporal motion buffer. A motion field for encoding or decoding a video block is generated based on the virtual temporal affine candidates. In one embodiment, collocated motion candidates are rescaled by adjusting the picture order count of the determined motion field. In another embodiment, resolution adaptation is performed to enable a current motion buffer to correspond to a reference motion buffer.

Abstract: Different implementations are described, particularly implementations for video encoding and decoding based on wherein the partitioning tree structure is partially shared between luma and chroma blocks are presented. According to an implementation, a single partitioning tree structure is shared between luma and chroma blocks from a root node of the partitioning tree down to a switching node and a dual partitioning tree structure is determined for luma and chroma blocks from the switching node down to a leaf node of the partitioning tree. Thus, this implementation optimizes the coding efficiency by allowing separated trees for smaller blocks, while limiting the complexity of decoding pipeline.

Abstract: Different implementations are described for determining one or more illumination compensation parameters for a current block being encoded by a video encoder or decoded by a video decoder. A plurality of motion vectors for a current block being encoded in a picture are determined. One or more illumination compensation parameters for each of the plurality of motion vectors are determined and encoded or decoded. The current block is then encoded or decoded using the plurality of motion vectors and the one or more illumination compensation parameters for each of the plurality of motion vectors. In one embodiment, a flag is used to signal the use or not of the illumination compensation. In another embodiment, the illumination compensation flag is not encoded or decoded if illumination compensation is not used.

Abstract: A decoding method for decoding an image is disclosed. The decoding method comprises for at least one slice of the image: —decoding (S210) the slice from a bitstream; —determining (S230) information representative of a size of a region of the decoded slice, the size being different from a size of a basic coding block used for decoding the slice; and—filtering (S240) the decoded slice by applying a filter on the region identified by the determined information.

Abstract: A method for encoding a picture block is disclosed. A predictor is determined as a weighted sum of sample values of a first motion compensated reference block in a first reference image and of a second motion compensated reference block in a second reference image. Then, a residual block determined from the picture block and the predictor is encoded in a bitstream. Advantageously, the weights of the weighted sum are determined by minimizing an error between reconstructed samples neighboring the picture block and samples neighboring the first and second reference blocks.

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 a method and an apparatus are presented for improving parallelization for wavefront parallel encoding and decoding of luma and chroma components of a vide picture. For example, a luma component and a chroma component of a video picture are independently subdivided into respectively a plurality of luma coding units and a plurality of chroma coding units. A context-based adaptive binary coding context variable is propagated from a previous row to a current row of the independently subdivided plurality of luma coding units, and a context-based adaptive binary coding context variable is propagated from a previous row to a current row of the independently subdivided plurality of chroma coding units. The video picture is encoded or decoded using the propagations to provide the wavefront parallel processing.

Abstract: In a particular implementation, a video decoder may decode an initial motion vector predictor from the bitstream for a current block, and perform motion search in a small search window to refine the initial motion vector predictor. The initial motion vector may be rounded before being refined. The motion refinement can be based on a discontinuity measure between pixels of a current block and pixels of adjacent block, and can also be based on gradients between the current block and adjacent blocks. The motion vector for the current block is then decoded based on the refined motion vector predictor, and the motion vector difference if there is any. The motion refinement can also be performed on the motion vector for the current block directly. Through motion refinement, the decoder may increase the motion resolution. A corresponding video encoder may choose whether to use motion refinement based on encoder decisions.

Abstract: A block of video data is split and coded using existing transform sizes through one of several embodiments. In one embodiment, the block is split in a single splitting operation. In another embodiment, a video block is split in a series of splitting operations. Successive divisions using asymmetric splitting are forbidden if an equivalent split can be attained using triple splitting. In another embodiment, a video block is split using successive splits, but the second type of split is dependent on the first type of split. Methods, apparatus, and signal embodiments are provided for encoding and decoding.