A method, computer program, and computer system is provided for aligning across layers in a coded video stream. A video bitstream having multiple layers is decoded. One or more subpicture regions are identified from among the multiple layers of the decoded video bitstream, the subpicture regions including a background region and one or more foreground subpicture regions. An enhanced subpicture is decoded and displayed based on a determination that a foreground subpicture region is selected. The background region is decoded and displayed based on a determination that a foreground subpicture region was not selected.

A method, computer program, and computer system is provided for aligning across layers in a coded video stream. A video bitstream having multiple layers is decoded. One or more subpicture regions are identified from among the multiple layers of the decoded video bitstream, the subpicture regions including a background region and one or more foreground subpicture regions. An enhanced subpicture is decoded and displayed based on a determination that a foreground subpicture region is selected. The background region is decoded and displayed based on a determination that a foreground subpicture region was not selected.

According to an embodiment of the present document, a method for increasing the accuracy of in-loop filtering is proposed. In an example, the filtering accuracy of chroma blocks can be improved on the basis of luma blocks by performing a cross component adaptive loop filtering process.

A decoder comprises circuitry and memory. The circuitry, using the memory, in operation, determines a number of first pixels and a number of second pixels used in a deblocking filter process, wherein the first pixels are located at an upper side of a block boundary and the second pixels are located at a lower side of the block boundary, and performs the deblocking filter process on the block boundary. The number of the first pixels and the number of the second pixels are selected from among candidates, wherein the candidates include at least 4 and M larger than 4. Response to a location of the block boundary being a predetermined location, the number of the first pixels used in the deblocking filter process is limited to be 4.

A method, computer program, and computer system is provided for video encoding and decoding. Video data including one or more frames is received. One or more quantization parameters associated with the received video data are determined for frame generation or enhancement of a target frame from among the one or more frames. The video data is decoded based on the determined quantization parameters.

An image decoding method according to the present disclosure presents indication information related to whether deblocking parameters for a deblocking filtering procedure exist in a picture header or a slice header.

An image decoding method according to the present disclosure presents indication information related to whether deblocking parameters for a deblocking filtering procedure exist in a picture header or a slice header.

A (decoded) picture may be split into subpictures/tiles. Information on the subpictures may be obtained by a decoding device, and a decoding procedure may be performed on the basis of the information on the subpictures. In addition, information on the tiles may be obtained by a decoding device, and a decoding procedure may be performed on the basis of the information on the tiles. According to embodiments of the present document, subpicture-related information and tile-related information can be efficiently signaled, and an in-loop filtering procedure can be performed on the basis of the subpicture-related information.

A (decoded) picture may be split into subpictures/tiles. Information on the subpictures may be obtained by a decoding device, and a decoding procedure may be performed on the basis of the information on the subpictures. In addition, information on the tiles may be obtained by a decoding device, and a decoding procedure may be performed on the basis of the information on the tiles. According to embodiments of the present document, subpicture-related information and tile-related information can be efficiently signaled, and an in-loop filtering procedure can be performed on the basis of the subpicture-related information.

Several techniques for video encoding and video decoding are described. One example method includes performing a conversion between a video picture of a video comprising one or more slices and a bitstream of the video picture according to a rule. The rule specifies that that whether a first syntax element indicating a usage of a coding tool is present at a first level is based on a syntax flag indicating whether a syntax structure of a second level is not present at the first level, wherein the second level is higher than the first level, and wherein the second level is the video picture level or higher than the video picture level.