Abstract: 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 to 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.

Abstract: Described are methods and devices for 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.

Abstract: 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.

Abstract: At least a method and an apparatus are presented for efficiently encoding or decoding video. For example, an intra prediction of an image block using at least one neural network from a context comprising pixels surrounding the image block is determined and an information relative to a transform method to apply for decoding the image block is also determined. The transform method is adapted to the neural network intra prediction mode of the block to encode or decode. The information relative to the transform method is inferred from the at least one neural network used in intra prediction of the image block at the encoding and either signaled or also inferred at the decoding.

Abstract: Video processing can involve encoding and/or decoding a picture based on determining an activation of a processing mode involving a motion vector refinement process and a second process other than the motion vector refinement process; modifying the motion vector refinement process based on the activation and the second process; and encoding and/or decoding the picture based on the modified motion vector refinement process and the second process.

Abstract: 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.

Abstract: A method and an apparatus for deep prediction refinement are disclosed. A first motion-compensated region for a block of a picture and a second region for said block are obtained. A prediction for said block is determined using a Neural Network that uses said first motion-compensated region and said second region.

Abstract: In some coding modes, such as the merge mode, a list of motion candidates is generated using spatial or temporal neighboring blocks or constructed ones, and one of the motion candidates is inherited by the current block. When constructing the list of motion candidates, motion information of a candidate to be added is checked to limit the redundancy in the constructed list. In one implementation, the switchable interpolation filter, the IFindex becomes part of the motion information to be used in comparison since it can modify the resulting prediction. Furthermore, the GBiIdx indicating the weights used in bi-prediction can also be part of the motion information to be compared and could also be taken into account in the redundancy check. In general, all or part of motion information that causes different prediction can be used in redundancy check.

Abstract: There is provided intra predicting of an image block using at least one neural network from a context comprising pixel surrounding said image block. Said intra predicting also uses an information to distinguish the missing pixels from the available pixels in the context. There are also provided encoding/decoding methods and apparatus, a device, a non-transitory computer readable medium and a computer program product.

Abstract: Inferring an illumination compensation flag during encoding or decoding of a video image signal using frame rate up conversion can save one bit and eliminate complexity. The illumination compensation flag can be derived from the corresponding flags of at least one bi-predictive or bi-directional prediction candidates. The flag can also be derived from some function of the flags from those candidates. Alternatively, several flags can be used for respective coding or decoding of blocks if there are more than one prediction candidate using illumination compensation.

Abstract: 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.

Abstract: A method comprising: obtaining (601) 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.

Abstract: Flexible methods to use a combination of coding modes while keeping good performance tradeoff are implemented with embodiments that determine coding mode information. In one embodiment, determination is made of activation of a first coding mode, and upon determination of whether a second coding mode is used, coding or decoding using the determined modes occurs. Other embodiments enable use of multiple reference lines, intra sub-block partitioning, matrix intra prediction, and low frequency non-separable transforms.

Abstract: A method for reconstructing a picture block is disclosed, wherein the block is predicted using local illumination compensation. The parameters of local illumination compensation are determined according to a selection of reconstructed samples located to the left and above of the current block. In the case where some of them are unavailable, they may be replaced using different techniques.

Abstract: A method and an apparatus for encoding or decoding a video are provided. At least one motion compensation interpolation filter for a block of the video is determined. In an embodiment, the length of the motion compensation interpolation filter is adapted based on block conditions. A prediction block is determined based on the at least one motion compensation interpolation filter and a reference block determined for the block and the block of the video is encoded or decoded based at least on the prediction block.

Abstract: 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.

Abstract: Decoding and encoding methods and apparatuses are described for at least one first block level parameter for a current block. Bi-directional Optical flow mode allowing refining a motion of samples of a block based on an optical flow for the current block is disabled responsive to the at least one first block level parameter indicating generalized bi-prediction weights are not equal to default weights. The current block is then decoded or encoded accordingly.

Abstract: Various embodiments relate to a video coding system in which some elements required for decoding are generated according to a process that not specified within the video coding system. This process is hereafter referenced to as being the “external” process. This external process may generate “external” reference pictures to be used by a decoder that is adapted to use these external pictures. Encoding method, decoding method, encoding apparatus, decoding apparatus based on this post-processing method are proposed.

Abstract: Methods and apparatuses to improve compression efficiency in a video compression scheme are described to enable flexible use of local illumination compensation. Such methods comprise individual local illumination compensation for components of a video block. Such methods also comprise flexible derivation methods for illumination compensation information. In one embodiment, local illumination compensation information can be inherited from other others, such as neighboring blocks.

Abstract: A method for decoding a video sequence representing original video data comprising a first picture of the video sequence having a feature related to a chroma component of the first picture different from a same feature related to a chroma component of a second picture of the video sequence, the feature related to a chroma component being representative of a chroma format and/or of a relative position of chroma samples with respect to luma samples.