The present disclosure relates to an image decoding device, an image decoding method, an image encoding device, and an image encoding method that enable further improvement of practicality.

Reference image information indicating a reference image to be referred to by a current picture is saved in a header region of an access unit. The reference image information is saved in an AUD NAL unit indicating a delimiter of the access unit or a NEW NAL unit provided separately from the AUD NAL unit, and is applied to all tile group NAL units in the access unit. The present technology can be applied to, for example, an image decoding device and an image encoding device.

A first predictor is applied to an input image to generate first-stage predicted codewords approximating prediction target codewords of a prediction target image. Second-stage prediction target values are created by performing an inverse cascade operation on the prediction target codewords and the first-stage predicted codewords. A second predictor is applied to the input image to generate second-stage predicted values approximating the second-stage prediction target values. Multiple sets of cascade prediction coefficients are generated to comprise first and second sets of cascade prediction coefficients specifying the first and second predictors. The multiple sets of cascade prediction coefficients are encoded, in a video signal, as image metadata. The video signal is further encoded with the input image.

Methods, apparatus, systems and articles of manufacture for video coding using object metadata are disclosed. An example apparatus includes an object separator to separate input views into layers associated with respective objects to generate object layers for geometry data and texture data of the input views, a pruner to project the first object layer of a first basic view of the at least one basic views against the first object layer of a first additional view of the at least one additional views to generate a first pruned view and a first pruning mask, a patch packer to tag a patch with an object identifier of the first object, the patch corresponding to the first pruning mask, and an atlas generator to generate at least one atlas to include in encoded video data, the atlas including the patch.

Methods, apparatus, systems and articles of manufacture for video coding using object metadata are disclosed. An example apparatus includes an object separator to separate input views into layers associated with respective objects to generate object layers for geometry data and texture data of the input views, a pruner to project the first object layer of a first basic view of the at least one basic views against the first object layer of a first additional view of the at least one additional views to generate a first pruned view and a first pruning mask, a patch packer to tag a patch with an object identifier of the first object, the patch corresponding to the first pruning mask, and an atlas generator to generate at least one atlas to include in encoded video data, the atlas including the patch.

A video processing method includes performing a conversion between a video having one or more video layers including one or more video pictures and a bitstream of the video according to a rule. The rule specifies a condition under which no picture that has been generated by a decoding process for generating an unavailable reference picture is referred to by an active entry in a reference picture list of a current slice of a current picture.

Methods, devices and systems for configuring different access units in scalable video coding are described. In one example aspect, a method of video processing include performing a conversion between a video comprising one or more pictures in one or more video layers and a bitstream of a video, wherein the bitstream comprises a coded video sequence that includes one or more access units, and wherein the bitstream further comprises a first syntax element indicating whether an access unit includes a picture for each video layer making up the coded video sequence.

A method, computer program, and computer system is provided for coding video data. Video data including one or more subpictures is received. A network abstraction layer (NAL) unit type associated with each of the one or more subpictures is identified based on checking a flag corresponding to mixed NAL units in the one or more subpictures. The video data is decoded based on the identified NAL unit types.

An encoder includes circuitry and memory coupled to the circuitry. In operation, the circuitry: encodes information for deriving a parameter into a header of a bitstream; filters reconstructed samples in a first image using a filtering process, to generate a second image; determines whether the parameter has a predefined value; encodes a third image using the second image when the parameter has the predefined value; and encodes the third image using the first image when the parameter does not have the predefined value.

An image encoding/decoding method and apparatus are provided. An image decoding method performed by an image decoding apparatus may comprise parsing weight information specifying a weight for a reference sample from a bitstream according to a weight parameter syntax structure, and decoding a current block by performing inter prediction based on the weight information. The parsing according to the weight parameter syntax structure may comprise obtaining weight number information specifying the number of weight information obtained from the bitstream according to the weight parameter syntax structure and obtaining weight information from the weight parameter syntax structure based on the weight number information.

The present invention is concerned with decoders, encoders and corresponding methods for handling video data streams (11) comprising a first sub-bitstream (11-1) and a second sub-bitstream (11-2). The herein described concept provides solutions for mixing, within an access unit (30, 31, 32), different NAL units (301, 302, 3030, 304) of different NAL unit types. For example, RAP NAL unit types may be mixed with different IRAP NAL unit types or non-IRAP NAL unit types, and non-IRAP NAL unit types may be mixed with different non-IRAP NAL unit types.