Interdigital Ce Patent Holdings, Sas

Interdigital Vc Holdings, Inc.

Interdigital Madison Patent Holdings, Sas

Interdigital Vc Holdings France, Sas

Philippe De Lagrange

Edouard Francois

Philippe Bordes

Tangi Poirier

Karam Naser

Franck Galpin

Fabrice LeLeannec

Ya Chen

Fabrice Leleannec

Fabrice Le Leannec

Fabrice Urban

Pierre Andrivon

Franck Hiron

Christophe Chevance

Srinivas Gudumasu

Gaëlle Martin-Cocher

A method and apparatus to improve compression efficiency in a video compression scheme enables use of switchable interpolation filters. The interpolation filters are used on multiple partitions of video blocks, enabling better motion compensated prediction and improved video coding efficiency. In one embodiment, an interpolation filter index is derived for triangle partitions of a block from motion information candidate parameters, so that each unidirectional motion compensation can use a different value of interpolation filter index. In another embodiment, an interpolation filter index is a function of characteristics, such as shape or area, of video partitions.

Switchable interpolation filters

A method for reconstructing a block of a picture comprising: applying an inverse transform to a block of transform coefficients using a first matrix of integer coefficients representative of the inverse transform, wherein the first matrix of integer coefficients is the inverse of a second matrix of integer coefficients representative of a transform inverted to obtain the inverse transform, the second matrix of integer coefficients being derived from a third matrix of integer coefficients, the absolute values of the integer coefficients of the third matrix taking their values in a set of four different values, the derivation comprising a modification of one value of the set to ensure that a sum of two values of the set equals a third value of the set.

High precision 4×4 DST7 and DCT8 transform matrices

A method and apparatus to improve compression efficiency in a video compression scheme enables separate control of a local chroma quantization parameter. The control can be used to disable a local chroma quantization parameter. One embodiment uses an existing local luma quantization parameter control flag for controlling local chroma quantization parameter. Another embodiment includes a separate local chroma quantization parameter control flag. Bitstream syntax is used to convey the flags.

High-level constraint flag for local chroma quantization parameter control

A method for video decoding ensuring a consistent interaction of some signaling tools with some encoding tools. The method is particularly advantageous when a container intended to provide parameters required for applying an encoding tool is missing while the encoding tool is activated for a given block. Examples include obtaining a first information indicating if a container of a first type providing at least one coding parameter is absent from the bitstream; checking a value of a first syntax element indicating if a coding tool using said at least one coding parameter is activated for a current block of samples of an image of the video sequence; and, adapting a decoding of the current block in case of absence of the container when the second syntax element indicates an activation of the coding tool.

Method and device for consistent interaction of signaling tools with encoding tools in video decoding

Coding mode information of a current block is propagated to neighbor blocks even when the coding mode is not selected for a current block. Such propagation may be limited, for example to one block only or to multiple generation of copies. Different propagation modes are proposed: left to right direction, top to bottom direction, bottom-right diagonal direction, first available information, or last coded information. The coding mode propagation allows to improve further predictions since a further block will benefit from the information from its neighbors.

Coding mode information propagation for video coding

A method comprising: obtaining () a syntax element associated with video data, wherein said syntax element specifies that a cross-color component transform process in which at least one second color component is transformed based on at least one first color component different from the second color component is to be applied to the video data as a post processing process following a decoding process to be applied to the video data.

Method and device for luma mapping with cross component scaling

An image is split into a plurality of blocks of various sizes and a subdivision level counter is associated to each of the blocks. The value of this subdivision level counter for a block is representative of the size of the block and is used to determine the quantization parameter for the block. The value is propagated for each subdivision and incremented according the type of the subdivision. When the image is split, an analysis is done according to the subdivision level counter, a maximal value of subdivision and the type of split, in order to determine the start of a new quantization group and when it is the case, the current position of the partition is propagated to the further split partitions to be stored with these partition and serve in the prediction process when decoding.

Quantization for video encoding or decoding based on the surface of a block

To encode a picture, a coding tree unit (CTU) in the picture is partitioned by a quadtree structure, and the quadtree leaf nodes can be further partitioned by a multi-type tree (MTT) structure. To increase the set of reachable coding tree nodes and leaves, we propose to increase the maximum allowed MTT hierarchy depth to be twice the difference between the CTU size and the minimum allowed size for a CU. The maximum allowed MTT hierarchy depth can be specified for all QT levels in order to provide more flexibility in the split tree. Alternatively, only two levels of maximum allowed MTT depth are signaled: one when QT splits are allowed, and another one when no more QT splits are allowed. In addition, an upper bound can be set for the minimum allowed coding block size, based on the coding tree unit size or the maximum allowed transform size.

Coding tree partitioning

At least a method and an apparatus are presented for efficiently encoding or decoding video. For example, one or more chroma residual scaling parameters are determined based one or more luma mapping parameters and based on a corrective value of the one or more chroma residual scaling parameters. The video is encoded or decoded based on the determined one or more chroma residual scaling parameters.

Chroma residual scaling foreseeing a corrective value to be added to luma mapping slope values

Different implementations are described, particularly implementations for video encoding and decoding are presented including a method for deblocking an image. According to an implementation, in a method for deblocking an image, at least one boundary is determined between a first block of samples and a second block of samples: a boundary strength is determined according to at least one of a prediction mode of the first block and a prediction mode of the second block; and samples of the first and second blocks neighboring the at least one boundary are filtered according to the boundary strength. Advantageously, in case the prediction mode of the first block is a weighted prediction mode, the boundary strength further depends on the relative weight of samples used in predicting the first block of samples according to the weighted prediction mode of the first block and reciprocally for the second block.

Method and apparatus for deblocking an image

An apparatus for processing a video may receive a quantization parameter (QP) adjustment value associated with a syntax level at the syntax level. In examples, the apparatus may obtain the QP adjustment value associated with the syntax level, for example, via signalling at the syntax level. The apparatus may apply the QP adjustment value to a QP associated with the syntax level to obtain an adjusted QP associated with the syntax level. The syntax level may include a coding block level or a transform unit (TU) level. In examples, if the syntax level is a TU level, the decoder may receive the QP adjustment value for a first CU (for example, a current TU) and obtain a QP for the second TU that precedes the first CU in a coding order based on a QP predictor, for example, instead of the QP adjustment value for the first TU.

Quantization parameter coding

A method for reconstructing a block of an image, said block comprising a plurality of components and being predictively encoded from a reference block, includes if a single quantized residual block is used to jointly encode at least two components of the plurality of components, deriving at least one quantization matrix from a plurality of scaling lists each defined for one component of the plurality of components; and, applying one of the at least one derived quantization matrix to the single quantized residual block to obtain a reconstructed residual block for each of the at least two components.

Derivation of quantization matrices for joint Cb-Br coding

A decoding method is disclosed. A quantization parameter of at least one luma block is obtained. The at least one luma block comprises a luma sample co-located with at least one chroma sample selected in a current chroma block. The luma and chroma blocks are coded in dual tree mode. A quantization parameter of the current chroma block is then determined responsive to the quantization parameter of the at least one luma block. Finally, the current chroma block is decoded using the quantization parameter of the current chroma block.

Method and apparatus for determining chroma quantization parameters when using separate coding trees for luma and chroma

Different quantization matrices may be transmitted corresponding to different block sizes, color components and prediction modes. To more efficiently signal the coefficients of the quantization matrices, in one implementation, a unified matrix identifier matrixId is used, based on a size identifier (sizeId) that relates to CU size with larger sizes listed first, and a matrix type (matrixTypeId) with luma QMs listed first. For example, the unified identifier is derived as: matrixId=N*sizeId+matrixTypeId, where N is the number of possible type identifiers, e.g., N=6. This single identifier allows referring to any previously transmitted matrix when using prediction (copy), and transmitting larger matrices first avoids interpolation in the prediction process. When a block uses the Intra Block Copy prediction mode, QM identifier may be derived as if the block uses the INTER prediction mode.

Single-index quantization matrix design for video encoding and decoding

Decoding and/or encoding video information included in a bitstream can involve a predicted quantization matrix associated with at least a portion of the video information and a syntax element indicating that at least one coefficient of the predicted quantization matrix is to be interpreted as a residual such that the decoding and/or encoding of at least a portion of the video information is based on a combination of the predicted quantization matrix and the residual, where the syntax element is obtained from the bitstream during decoding, or included in the bitstream during encoding.

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Cesson-Sevigne, France

Philippe De Lagrange