Method and computer-readable storage medium

Abstract

A method according to one aspect comprises the steps of: acquiring, from a bitstream, image information including a constituent rectangle (CR)-related message; and identifying, on the basis of the CR-related message, a subpicture associated with each of at least one constituent rectangle belonging to a specific layer among at least one layer, wherein the CR-related message may include, for the specific layer, subpicture index information indicating a subpicture associated with each constituent rectangle.

Description

Method and computer-readable storage medium

[0001] The present disclosure relates to a method for decoding / encoding image information, a computer-readable storage medium for storing image information, and a method for transmitting image information.

[0002] Recently, the demand for high-resolution, high-quality video, such as HD (High Definition) and UHD (Ultra High Definition), has been increasing across various fields. As video data becomes higher in resolution and quality, the relative amount of information or bits transmitted increases compared to conventional video data. This increase in transmitted information or bits leads to higher transmission and storage costs.

[0003] Accordingly, high-efficiency video compression technology is required to effectively transmit, store, and play back high-resolution, high-quality video information.

[0004] The present disclosure aims to provide an encoding / decoding method and / or apparatus with improved coding efficiency.

[0005] The present disclosure aims to provide an encoding / decoding method and / or apparatus having data transmission efficiency.

[0006] The technical problems to be solved in this disclosure are not limited to those mentioned above, and other technical problems not mentioned will be clearly understood by those skilled in the art to which this disclosure belongs from the description below.

[0007] A method according to one aspect comprises: acquiring image information including a message related to Constituent Rectangles (CR) from a bitstream; and identifying a subpicture associated with each of at least one constituent rectangles belonging to a specific layer among at least one layer based on the message related to the CR, wherein the message related to the CR may include subpicture index information representing a subpicture associated with each of the constituent rectangles for the specific layer.

[0008] The subpicture associated with each of the above-mentioned constituent rectangles may belong to the above-mentioned specific layer.

[0009] The above CR-related message may include index length information indicating information related to the length of the above subpicture index information.

[0010] The above CR-related message may include subpicture index availability information indicating whether the index length information is included in the above CR-related message.

[0011] The above subpicture index information may be included in the CR-related message based on the fact that the value of the above subpicture index availability information is 1.

[0012] The above CR-related message may include CR segmentation information indicating whether the above configuration rectangle is derived based on the above subpicture.

[0013] The above subpicture index information may be included in the above CR-related message based on the fact that the value of the above CR split information is 1 and the value of the above subpicture index availability information is 1.

[0014] A method according to one aspect comprises: generating a CR-related message for identifying a subpicture associated with each of at least one constituent rectangle for at least one specific layer; and encoding image information including the CR-related message, wherein the CR-related message may include subpicture index information representing a subpicture associated with each of the constituent rectangles for at least one specific layer.

[0015] The subpicture associated with each of the above-mentioned constituent rectangles may belong to the above-mentioned specific layer.

[0016] The above CR-related message may include index length information indicating information related to the length of the above subpicture index information.

[0017] The above CR-related message may include subpicture index availability information indicating whether the index length information is included in the above CR-related message.

[0018] The above subpicture index information may be included in the CR-related message based on the fact that the value of the above subpicture index availability information is 1.

[0019] The above CR-related message may include CR segmentation information indicating whether the above configuration rectangle is derived based on the above subpicture.

[0020] The above subpicture index information may be included in the above CR-related message based on the fact that the value of the above CR split information is 1 and the value of the above subpicture index availability information is 1.

[0021] A method according to one aspect comprises: a step of generating a bitstream; and a step of transmitting data including said bitstream; wherein the step of generating the bitstream comprises: a step of generating a CR-related message identifying a subpicture associated with each of at least one constituent rectangles for a specific layer among at least one layer; and a step of encoding image information including said CR-related message; and wherein the CR-related message may include subpicture index information representing a subpicture associated with each of the constituent rectangles for the specific layer.

[0022] A computer-readable storage medium according to one aspect can non-transiently store a bitstream generated by the above method.

[0023] The features briefly summarized above regarding the present disclosure are merely exemplary aspects of the detailed description of the present disclosure that follows and do not limit the scope of the present disclosure.

[0024] According to the present disclosure, an encoding / decoding method and / or apparatus with improved coding efficiency can be provided.

[0025] According to the present disclosure, an encoding / decoding method and / or apparatus having improved data transmission efficiency can be provided.

[0026] The effects obtainable from the present disclosure are not limited to those mentioned above, and other unmentioned effects will be clearly understood by those skilled in the art to which the present disclosure pertains from the description below.

[0027] FIG. 1 is a schematic diagram illustrating a video coding system to which an embodiment according to the present disclosure can be applied.

[0028] FIG. 2 is a schematic diagram showing an encoding device to which an embodiment according to the present disclosure can be applied.

[0029] FIG. 3 is a schematic diagram showing a decoding device to which an embodiment according to the present disclosure can be applied.

[0030] FIG. 4 shows an example of a video / image decoding method to which one embodiment can be applied.

[0031] FIG. 5 shows an example of a video / image encoding method to which an embodiment of the present disclosure can be applied.

[0032] Figure 6 illustrates an exemplary hierarchical structure for a coded video / image.

[0033] FIG. 7 is a diagram illustrating a method for encoding image information according to one embodiment.

[0034] FIG. 8 is a diagram illustrating a method for decoding image information according to one embodiment.

[0035] FIG. 9 is a diagram showing another example of a method for encoding image information according to one embodiment.

[0036] FIG. 10 is a diagram showing another example of a method for decoding image information according to one embodiment.

[0037] FIG. 11 is a drawing illustrating an exemplary content streaming system to which an embodiment according to the present disclosure can be applied.

[0038] Hereinafter, embodiments of the present disclosure are described in detail with reference to the attached drawings so that those skilled in the art can easily implement them. However, the present disclosure may be embodied in various different forms and is not limited to the embodiments described herein.

[0039] In describing the embodiments of the present disclosure, detailed descriptions of known configurations or functions are omitted if it is determined that such descriptions could obscure the essence of the present disclosure. Furthermore, parts of the drawings unrelated to the description of the present disclosure have been omitted, and similar parts are denoted by similar reference numerals.

[0040] In the present disclosure, when a component is described as being "connected," "combined," or "joined" with another component, this may include not only a direct connection but also an indirect connection in which another component exists in between. Furthermore, when a component is described as "comprising" or "having" another component, this means that, unless specifically stated otherwise, it does not exclude the other component but may include an additional component.

[0041] In the present disclosure, terms such as first, second, etc. are used solely for the purpose of distinguishing one component from another and do not limit the order or importance of the components unless specifically stated otherwise. Accordingly, within the scope of the present disclosure, a first component in one embodiment may be referred to as a second component in another embodiment, and likewise, a second component in one embodiment may be referred to as a first component in another embodiment.

[0042] In this disclosure, distinct components are intended to clearly describe their respective features and do not imply that the components are separate. That is, multiple components may be integrated to form a single hardware or software unit, or a single component may be distributed to form multiple hardware or software units. Accordingly, such integrated or distributed embodiments are included within the scope of this disclosure, unless otherwise noted.

[0043] In the present disclosure, the components described in various embodiments do not necessarily mean essential components, and some may be optional components. Accordingly, embodiments consisting of a subset of the components described in one embodiment are also included within the scope of the present disclosure. Furthermore, embodiments including additional components in addition to the components described in various embodiments are also included within the scope of the present disclosure.

[0044] The present disclosure relates to the encoding and decoding of images. For example, the methods and embodiments disclosed in this document may be applied to methods disclosed in the VVC (versatile video coding) standard, EVC (essential video coding) standard, AV1 (AOMedia Video 1) standard, AVS2 (2nd generation of audio video coding standard) or next-generation video / image coding standards (e.g., H.267 or H.268).

[0045] The present disclosure presents various embodiments relating to video / image coding, and unless otherwise stated, said embodiments may be performed in combination with one another.

[0046] Unless newly defined in this disclosure, the terms used herein may have the ordinary meanings commonly used in the technical field to which this disclosure belongs.

[0047] In this disclosure, "video" may refer to a set of images over time. In this disclosure, "picture" generally refers to a unit representing a single image at a specific time, and a slice / tile is a unit that constitutes a part of a picture in coding. A slice / tile may include one or more coding tree units (CTUs). A picture may be composed of one or more slices / tiles. A picture may be composed of one or more tile groups. A tile group may include one or more tiles. A brick may represent a rectangular area of ​​rows of CTUs within a tile in a picture. In this document, tile groups and slices may be used interchangeably. For example, in this document, a tile group / tile group header may be referred to as a slice / slice header.

[0048] In the present disclosure, "pixel" or "pel" may refer to the smallest unit constituting a picture (or image). Additionally, "sample" may be used as a term corresponding to pixel. A sample may generally represent a pixel or a pixel value, may represent only the pixel / pixel value of the luminance component, or may represent only the pixel / pixel value of the chroma component.

[0049] In this disclosure, "unit" may represent a basic unit of image processing. A unit may include at least one of a specific area of ​​a picture and information related to that area. A unit may include one luminance block and two chroma (e.g., cb, cr) blocks. Depending on the case, the term "unit" may be used interchangeably with terms such as "block" or "area." In general, an MxN block may include samples (or sample arrays) or a set (or array) of transform coefficients consisting of M columns and N rows.

[0050] In the present disclosure, "current block" may mean one of "current coding block," "current coding unit," "block to be encoded," "block to be decoded," or "block to be processed." When prediction is performed, "current block" may mean "current prediction block" or "block to be predicted." When transformation (inverse transformation) / quantization (inverse quantization) is performed, "current block" may mean "current transformation block" or "block to be transformed." When filtering is performed, "current block" may mean "block to be filtered."

[0051] In the present disclosure, "current block" may mean a block comprising both a luminous component block and a chroma component block, or "luma block of the current block," unless explicitly stated as a chroma block. The luminous component block of the current block may be expressed by including an explicit description of a luminous component block, such as "luma block" or "current luminous block." Additionally, the chroma component block of the current block may be expressed by including an explicit description of a chroma component block, such as "chroma block" or "current chroma block."

[0052] In the present disclosure, " / " and "," may be interpreted as "and / or." For example, "A / B" and "A, B" may be interpreted as "A and / or B." Additionally, "A / B / C" and "A, B, C" may mean "at least one of A, B and / or C."

[0053] In the present disclosure, "or" may be interpreted as "and / or". For example, "A or B" may mean 1) "A" only, 2) "B" only, or 3) "A and B". Alternatively, in the present disclosure, "or" may mean "additionally or alternatively".

[0054] FIG. 1 is a schematic diagram illustrating a video / image coding system to which an embodiment according to the present disclosure can be applied.

[0055] Referring to FIG. 1, a video / image coding system may include a first device (source device) and a second device (receiving device). The source device may transmit encoded video / image or data in the form of a file or streaming to the receiving device via a digital storage medium or a network.

[0056] The source device may include a video source, an encoding device, and a transmission unit. The receiving device may include a receiver, a decoding device, and a renderer. The encoding device may be called a video / image encoding device, and the decoding device may be called a video / image decoding device. The transmitter may be included in the encoding device. The receiver may be included in the decoding device. The renderer may include a display unit, and the display unit may be composed of a separate device or an external component.

[0057] A video source may acquire video / images through processes such as video / image capture, synthesis, or generation. The video source may include a video / image capture device and / or a video / image generation device. The video / image capture device may include, for example, one or more cameras, a video / image archive containing previously captured video / images, etc. The video / image generation device may include, for example, a computer, a tablet, and a smartphone, etc., and may generate video / images (electronically). For example, virtual video / images may be generated through a computer, etc., in which case the video / image capture process may be replaced by a process in which related data is generated.

[0058] The encoding device can encode input video / images. The encoding device can perform a series of procedures, such as prediction, transformation, and quantization, for compression and coding efficiency. The encoded data (encoded video / image information) can be output in the form of a bitstream.

[0059] The transmission unit can transmit encoded video / image information or data output in the form of a bitstream to the receiving unit of a receiving device via a digital storage medium or a network in the form of a file or streaming. The digital storage medium may include various storage media such as USB, SD, CD, DVD, Blu-ray, HDD, and SSD. The transmission unit may include elements for creating a media file through a predetermined file format and elements for transmission via a broadcasting / communication network. The receiving unit can receive / extract the bitstream and transmit it to a decoding device.

[0060] The decoding device can decode video / images by performing a series of procedures such as inverse quantization, inverse transform, and prediction corresponding to the operation of the encoding device.

[0061] The renderer can render the decoded video / image. The rendered video / image can be displayed through the display unit.

[0062] FIG. 2 is a schematic diagram illustrating an encoding device to which an embodiment according to the present disclosure can be applied.

[0063] Referring to FIG. 2, the encoding device (200) may be configured to include an image partitioner (210), a predictor (220), a residual processor (230), an entropy encoder (240), an adder (250), a filter (260), and a memory (270). The predictor (220) may include an inter-predictor (221) and an intra-predictor (222). The residual processor (230) may include a transformer (232), a quantizer (233), a dequantizer (234), and an inverse transformer (235). The residual processor (230) may further include a subtractor (231). The addition unit (250) may be referred to as a reconstructor or a reconstructed block generator. The above-described image segmentation unit (210), prediction unit (220), residual processing unit (230), entropy encoding unit (240), addition unit (250), and filtering unit (260) may be configured by one or more hardware components (e.g., an encoder chipset or processor) according to the embodiment. Additionally, the memory (270) may include a DPB (Decoded Picture Buffer) and may be configured by a digital storage medium. The hardware component may further include the memory (270) as an internal / external component.

[0064] The image segmentation unit (210) can divide an input image (or picture, frame) input to an encoding device (200) into one or more processing units. For example, the processing unit may be called a coding unit (CU). A coding unit may be recursively divided into a coding tree unit (CTU) or a largest coding unit (LCU) according to a QTBTTT (Quad-tree binary-tree ternary-tree) structure. For example, a single coding unit may be divided into multiple coding units of a deeper depth based on a quad-tree structure, a binary-tree structure, and / or a ternary-tree structure. For example, a quad-tree structure may be applied first, and a binary-tree structure and / or a ternary-tree structure may be applied later. Alternatively, a binary-tree structure may be applied first. A coding procedure according to the present disclosure may be performed based on the final coding unit that is no longer divided. In this case, based on coding efficiency according to image characteristics, the maximum coding unit may be used directly as the final coding unit, or, if necessary, the maximum coding unit may be recursively divided into lower-depth coding units so that a coding unit of the optimal size is used as the final coding unit. Here, the coding procedure may include procedures such as prediction, transformation, and restoration described later. As another example, the processing unit may further include a prediction unit (PU) or a transformation unit (TU). The prediction unit and the transformation unit may each be divided or partitioned from the final coding unit.The above prediction unit may be a unit of sample prediction, and the above transformation unit may be a unit that derives transformation coefficients and / or a unit that derives a residual signal from transformation coefficients.

[0065] The term "unit" may be used interchangeably with terms such as "block" or "area" depending on the context. In general, an MxN block may represent a set of samples or transform coefficients consisting of M columns and N rows. A sample can generally represent a pixel or a pixel value, and may represent only the pixel / pixel value of the luminance component or only the pixel / pixel value of the chroma component. A sample may be used to refer to a single picture (or image) as a term corresponding to a pixel or pel.

[0066] The encoding device (200) can generate a residual signal (residual block, residual sample array) by subtracting a prediction signal (predicted block, prediction sample array) output from an inter prediction unit (221) or an intra prediction unit (222) from an input image signal (original block, original sample array), and the generated residual signal is transmitted to a conversion unit (232). In this case, as illustrated, the unit that subtracts the prediction signal (predicted block, prediction sample array) from the input image signal (original block, original sample array) within the encoding device (200) may be called a subtraction unit (231). The prediction unit (220) can perform a prediction for a block to be processed (hereinafter, current block) and generate a predicted block (predicted block) containing prediction samples for said current block. The prediction unit (220) can determine whether intra prediction is applied or inter prediction is applied in units of the current block or CU. The prediction unit (220) can generate various information regarding prediction, such as prediction mode information, as described below in the description of each prediction mode, and transmit it to the entropy encoding unit (240). The information regarding prediction can be encoded in the entropy encoding unit (240) and output in the form of a bitstream.

[0067] The intra prediction unit (222) can predict the current block by referring to samples within the current picture. The referenced samples may be located near the current block or away from it, depending on the prediction mode. In intra prediction, the prediction modes may include a plurality of non-directional modes and a plurality of directional modes. The non-directional modes may include, for example, a DC mode and a Planar mode. The directional modes may include, for example, 33 directional prediction modes or 65 directional prediction modes, depending on the degree of fineness of the prediction direction. However, this is merely an example, and depending on the settings, more or fewer directional prediction modes may be used. The intra prediction unit (222) may also determine the prediction mode applied to the current block by using the prediction mode applied to the surrounding blocks.

[0068] The inter prediction unit (221) can derive a predicted block for the current block based on a reference block (reference sample array) specified by a motion vector on a reference picture. At this time, to reduce the amount of motion information transmitted in the inter prediction mode, motion information can be predicted in blocks, sub-blocks, or samples based on the correlation of motion information between neighboring blocks and the current block. The motion information may include a motion vector and a reference picture index. The motion information may further include information on the inter prediction direction (L0 prediction, L1 prediction, Bi prediction, etc.). In the case of inter prediction, neighboring blocks may include spatial neighboring blocks existing within the current picture and temporal neighboring blocks existing in the reference picture. The reference picture containing the reference blocks and the reference picture containing the temporal neighboring blocks may be the same or different from each other. The temporal neighboring blocks may be referred to by names such as collocated reference block, collocated CU (colCU), etc. A reference picture containing the aforementioned temporal surrounding blocks may be called a collocated picture (colPic). For example, the inter prediction unit (221) may construct a list of motion information candidates based on surrounding blocks and generate information indicating which candidate is used to derive the motion vector and / or reference picture index of the current block. Inter prediction may be performed based on various prediction modes, for example, in the case of skip mode and merge mode, the inter prediction unit (221) may use the motion information of surrounding blocks as motion information of the current block. In the case of skip mode, unlike merge mode, a residual signal may not be transmitted.In the motion vector prediction (MVP) mode, the motion vector of surrounding blocks is used as a motion vector predictor, and the motion vector of the current block can be indicated by signaling the motion vector difference.

[0069] The prediction unit (220) may generate a prediction signal based on various prediction methods and / or prediction techniques described below. For example, the prediction unit (220) may apply intra prediction or inter prediction for the prediction of the current block, as well as apply intra prediction and inter prediction simultaneously. A prediction method that applies intra prediction and inter prediction simultaneously for the prediction of the current block may be called combined inter and intra prediction (CIIP). Additionally, the prediction unit (220) may be based on an intra block copy (IBC) prediction mode or a palette mode for the prediction of the block. The IBC prediction mode or palette mode may be used for content video / video coding, such as in games, for example, screen content coding (SCC). IBC basically performs prediction within the current picture, but it may be performed similarly to inter prediction in that it derives a reference block within the current picture. That is, IBC may use at least one of the inter prediction techniques described in this document. Palette mode can be viewed as an example of intra-coding or intra-prediction. When palette mode is applied, sample values ​​within a picture can be signaled based on information regarding palette tables and palette indices.

[0070] The prediction signal generated through the prediction unit (220) can be used to generate a restoration signal or to generate a residual signal. The subtraction unit (231) can generate a residual signal (residual signal, residual block, residual sample array) by subtracting the prediction signal (predicted block, prediction sample array) output from the prediction unit (220) from the input image signal (original block, original sample array). The generated residual signal can be transmitted to the conversion unit (232).

[0071] The transformation unit (232) can generate transform coefficients by applying a transformation technique to a residual signal. For example, the transformation technique may include at least one of a Discrete Cosine Transform (DCT), a Discrete Sine Transform (DST), a Karhunen-Loeve Transform (KLT), a Graph-Based Transform (GBT), or a Conditionally Non-linear Transform (CNT). Here, GBT refers to a transformation obtained from a graph when the relationship information between pixels is represented as a graph. CNT refers to a transformation obtained based on a prediction signal generated using all previously reconstructed pixels. The transformation process may be applied to a block of pixels of the same size in a square, or to a block of variable size that is not square.

[0072] The quantization unit (233) can quantize the transformation coefficients and transmit them to the entropy encoding unit (240). The entropy encoding unit (240) can encode the quantized signal (information regarding the quantized transformation coefficients) and output it as a bitstream. The information regarding the quantized transformation coefficients may be called residual information. The quantization unit (233) can rearrange the block-shaped quantized transformation coefficients into a one-dimensional vector form based on the coefficient scan order, and can also generate information regarding the quantized transformation coefficients based on the one-dimensional vector-shaped quantized transformation coefficients.

[0073] The entropy encoding unit (240) can perform various encoding methods such as, for example, exponential Golomb, CAVLC (context-adaptive variable length coding), CABAC (context-adaptive binary arithmetic coding), etc. The entropy encoding unit (190) may encode information required for video / image restoration (e.g., values ​​of syntax elements) together or separately, in addition to quantized transform coefficients. The encoded information (e.g., encoded video / image information) may be transmitted or stored in the form of a bitstream in units of NAL (network abstraction layer) units. The video / image information may further include information regarding various parameter sets, such as an adaptation parameter set (APS), a picture parameter set (PPS), a sequence parameter set (SPS), or a video parameter set (VPS). Additionally, the video / image information may further include general constraint information. The signaling information, transmitted information, and / or syntax elements mentioned in the present disclosure may be included in the video / image information. The video / image information may be encoded through the encoding procedure described above and included in the bitstream.

[0074] The above bitstream may be transmitted via a network or stored in a digital storage medium. Here, the network may include a broadcasting network and / or a communication network, and the digital storage medium may include various storage media such as USB, SD, CD, DVD, Blu-ray, HDD, SSD, etc. A transmission unit (not shown) for transmitting a signal output from the entropy encoding unit (240) and / or a storage unit (not shown) for storing it may be provided as an internal / external element of the encoding device (200), or the transmission unit may be provided as a component of the entropy encoding unit (240).

[0075] The quantized transformation coefficients output from the quantization unit (233) can be used to generate a residual signal. For example, a residual signal (residual block or residual samples) can be restored by applying inverse quantization and inverse transformation to the quantized transformation coefficients through the inverse quantization unit (234) and the inverse transformation unit (235).

[0076] Meanwhile, LMCS (luma mapping with chroma scaling) may be applied during the picture encoding and / or restoration process.

[0077] The adder (250) can generate a reconstructed signal (reconstructed picture, reconstructed block, reconstructed sample array) by adding the reconstructed residual signal to the prediction signal output from the inter prediction unit (221) or the intra prediction unit (222). In cases where there is no residual for the block to be processed, such as when a skip mode is applied, the predicted block can be used as the reconstructed block. The adder (250) may be called a reconstructed unit or a reconstructed block generation unit. The generated reconstructed signal can be used for intra prediction of the next block to be processed within the current picture, and can also be used for inter prediction of the next picture after undergoing filtering as described below.

[0078] The filtering unit (260) can improve subjective / objective image quality by applying filtering to the restored signal. For example, the filtering unit (260) can generate a modified restored picture by applying various filtering methods to the restored picture, and can store the modified restored picture in memory (270), specifically in the DPB of memory (170). The various filtering methods may include, for example, deblocking filtering, sample adaptive offset, adaptive loop filter, bilateral filter, etc. The filtering unit (260) can generate various information regarding filtering and transmit it to the entropy encoding unit (240), as described below in the description of each filtering method. The information regarding filtering can be encoded in the entropy encoding unit (240) and output in the form of a bitstream.

[0079] The modified restored picture transmitted to the memory (270) can be used as a reference picture in the inter-prediction unit (221). Through this, the encoding device (200) can avoid prediction mismatches between the encoding device (200) and the decoding device when inter-prediction is applied, and can also improve encoding efficiency.

[0080] The DPB in memory (270) can store a modified restored picture to be used as a reference picture in the inter prediction unit (221). Memory (270) can store motion information of blocks from which motion information is derived (or encoded) in the current picture and / or motion information of blocks in the picture that have already been restored. The stored motion information can be transmitted to the inter prediction unit (221) to be used as motion information of spatially surrounding blocks or motion information of temporally surrounding blocks. Memory (270) can store restoration samples of restored blocks in the current picture and transmit them to the intra prediction unit (222).

[0081] FIG. 3 is a schematic diagram illustrating a decoding device to which an embodiment according to the present disclosure can be applied.

[0082] As illustrated in FIG. 3, the decoding device (300) may be configured to include an entropy decoder (310), a residual processor (320), a predictor (330), an adder (340), a filter (350), and a memory (360). The predictor (330) may include an inter-predictor (332) and an intra-predictor (331). The residual processor (320) may include a dequantizer (321) and an inverse transformer (321). The aforementioned entropy decoding unit (310), residual processing unit (320), prediction unit (330), addition unit (340), and filtering unit (350) may be configured by a single hardware component (e.g., a decoder chipset or a processor) according to an embodiment. Additionally, the memory (360) may include a decoded picture buffer (DPB) and may be configured by a digital storage medium. The hardware component may further include the memory (360) as an internal / external component.

[0083] When a bitstream containing video / image information is input, the decoding device (300) can restore the image by performing a process corresponding to the process performed by the encoding device (200) of FIG. 2. For example, the decoding device (300) can perform decoding using a processing unit applied in the encoding device (200). Thus, the processing unit for decoding may be, for example, a coding unit. The coding unit may be a coding tree unit, or a maximum coding unit may be obtained by dividing it according to a quad tree structure, a binary tree structure, and / or a binary tree structure. And, the restored image signal decoded and output through the decoding device (300) can be played back through a playback device (not shown).

[0084] The decoding device (300) can receive a signal output from the encoding device (200) of FIG. 2 in the form of a bitstream. The received signal can be decoded through an entropy decoding unit (310). For example, the entropy decoding unit (310) can parse the bitstream to derive information necessary for image restoration (or picture restoration) (e.g., video / image information). The video / image information may further include information regarding various parameter sets, such as an adaptation parameter set (APS), a picture parameter set (PPS), a sequence parameter set (SPS), or a video parameter set (VPS). Additionally, the video / image information may further include general constraint information. The decoding device (300) can decode the picture based on the information regarding the parameter sets and / or the general constraint information. The signaling / received information and / or syntax elements described below can be obtained from the bitstream by decoding through the decoding procedure. For example, the entropy decoding unit (310) can decode information within the bitstream based on coding methods such as exponential chord coding, CAVLC, or CABAC, and output values ​​of syntax elements required for image restoration and quantized values ​​of transformation coefficients regarding residuals. More specifically, the CABAC entropy decoding method can receive bins corresponding to each syntax element in the bitstream, determine a context model using information on the syntax element to be decoded and decoding information of surrounding and decoding target blocks or information on symbols / bins decoded in the previous step, predict the probability of occurrence of the bin according to the determined context model, and perform arithmetic decoding of the bin to generate a symbol corresponding to the value of each syntax element.At this time, the CABAC entropy decoding method can update the context model using the decoded symbol / bin information for the context model of the next symbol / bin after determining the context model. Among the information decoded in the entropy decoding unit (310), information regarding prediction is provided to the prediction unit (330), and residual values ​​for which entropy decoding was performed in the entropy decoding unit (310), i.e., quantized transformation coefficients and related parameter information, can be input to the residual processing unit (320). The residual processing unit (320) can derive residual signals (residual blocks, residual samples, residual sample array). Additionally, among the information decoded in the entropy decoding unit (310), information regarding filtering can be provided to the filtering unit (350). Meanwhile, a receiving unit (not shown) that receives a signal output from an encoding device may be further configured as an internal / external element of the decoding device (300), or the receiving unit may be a component of the entropy decoding unit (310). Meanwhile, the decoding device according to the present document may be called a video / image / picture decoding device, and the decoding device may be divided into an information decoder (video / image / picture information decoder) and a sample decoder (video / image / picture sample decoder). The information decoder may include the entropy decoding unit (310), and the sample decoder may include at least one of the inverse quantization unit (321), inverse transform unit (322), adder (340), filtering unit (350), memory (360), inter prediction unit (332), and intra prediction unit (331).

[0085] In the inverse quantization unit (321), the quantized transformation coefficients can be inversely quantized to output transformation coefficients. The inverse quantization unit (321) can rearrange the quantized transformation coefficients into a two-dimensional block form. In this case, the rearrangement can be performed based on the coefficient scan order performed in the encoding device (200). The inverse quantization unit (321) can perform inverse quantization on the quantized transformation coefficients using quantization parameters (e.g., quantization step size information) and obtain transformation coefficients.

[0086] In the inverse conversion unit (322), the conversion coefficients can be inversely converted to obtain a residual signal (residual block, residual sample array).

[0087] The prediction unit (330) can generate a prediction signal based on various prediction methods described below. For example, the prediction unit may apply intra prediction or inter prediction for a single block, and may also apply intra prediction and inter prediction simultaneously. This may be called combined inter and intra prediction (CIIP). Additionally, the prediction unit may be based on an intra block copy (IBC) prediction mode or a palette mode for predicting a block. The IBC prediction mode or palette mode may be used for content video / video coding, such as in games, for example, screen content coding (SCC). IBC basically performs prediction within the current picture, but it can be performed similarly to inter prediction in that it derives a reference block within the current picture. That is, IBC may use at least one of the inter prediction techniques described in this document. The palette mode can be viewed as an example of intra coding or intra prediction. When the palette mode is applied, information regarding the palette table and palette index can be included in the above video / image information and signaled.

[0088] The intra prediction unit (331) can predict the current block by referring to samples within the current picture. The description of the intra prediction unit (222) may be applied equally to the intra prediction unit (331). The referenced samples may be located in the neighborhood of the current block or located away from it, depending on the prediction mode. In intra prediction, the prediction modes may include a plurality of non-directional modes and a plurality of directional modes. The intra prediction unit (331) may determine the prediction mode applied to the current block by using the prediction mode applied to the neighboring blocks.

[0089] The inter prediction unit (332) can derive a predicted block for the current block based on a reference block (reference sample array) specified by a motion vector on a reference picture. At this time, to reduce the amount of motion information transmitted in the inter prediction mode, motion information can be predicted in blocks, sub-blocks, or samples based on the correlation of motion information between neighboring blocks and the current block. The motion information may include a motion vector and a reference picture index. The motion information may further include information on the inter prediction direction (L0 prediction, L1 prediction, Bi prediction, etc.). In the case of inter prediction, neighboring blocks may include spatial neighboring blocks existing within the current picture and temporal neighboring blocks existing in the reference picture. For example, the inter prediction unit (332) may construct a motion information candidate list based on the neighboring blocks and derive the motion vector and / or reference picture index of the current block based on the received candidate selection information. Inter-prediction can be performed based on various prediction modes (techniques), and information regarding the prediction may include information indicating the mode (technique) of inter-prediction for the current block.

[0090] The adder (340) can generate a restoration signal (restored picture, restored block, restored sample array) by adding the acquired residual signal to the prediction signal (predicted block, predicted sample array) output from the prediction unit (330) (including the inter prediction unit (332) and / or intra prediction unit (331)). In cases where there is no residual for the block to be processed, such as when a skip mode is applied, the predicted block can be used as the restoration block. The description of the adder (250) can be applied equally to the adder (340). The adder (340) may be called a restoration unit or a restoration block generation unit. The generated restoration signal can be used for intra prediction of the next block to be processed within the current picture, and can also be used for inter prediction of the next picture after undergoing filtering as described below.

[0091] Meanwhile, LMCS (luma mapping with chroma scaling) may be applied during the picture decoding process.

[0092] The filtering unit (350) can improve subjective / objective image quality by applying filtering to the restored signal. For example, the filtering unit (350) can generate a modified restored picture by applying various filtering methods to the restored picture, and can store the modified restored picture in memory (360), specifically in the DPB of memory (360). The various filtering methods may include, for example, deblocking filtering, sample adaptive offset, adaptive loop filter, bilateral filter, etc.

[0093] The (modified) restored picture stored in the DPB of the memory (360) can be used as a reference picture in the inter-prediction unit (332). The memory (360) can store motion information of blocks from which motion information within the current picture has been derived (or decoded) and / or motion information of blocks within the picture that have already been restored. The stored motion information can be transmitted to the inter-prediction unit (332) to be used as motion information of spatially surrounding blocks or motion information of temporally surrounding blocks. The memory (360) can store restoration samples of blocks restored within the current picture and transmit them to the intra-prediction unit (331).

[0094] In this specification, the embodiments described in the filtering unit (260), inter prediction unit (221), and intra prediction unit (222) of the encoding device (200) may be applied to the filtering unit (350), inter prediction unit (332), and intra prediction unit (331) of the decoding device (300) in the same or corresponding manner.

[0095] FIG. 4 shows an example of a video / image decoding method to which one embodiment can be applied.

[0096] In video coding, the pictures constituting the video can be decoded according to a series of decoding orders. The picture order corresponding to the output order of the decoded pictures can be set differently from the decoding order, and based on this, not only forward prediction but also reverse prediction can be performed during inter-prediction.

[0097] In FIG. 4, S400 may be performed in the entropy decoding unit (310) of the aforementioned decoding device (300), S410 may be performed in the prediction unit (330), S420 may be performed in the residual processing unit (320), S430 may be performed in the addition unit (340), and S440 may be performed in the filtering unit (350). S400 may include a decoding procedure according to the present disclosure, S410 may include an inter / intra prediction procedure according to the present disclosure, S420 may include a residual processing procedure according to the present disclosure, S430 may include a block / picture restoration procedure according to the present disclosure, and S440 may include an in-loop filtering procedure according to the present disclosure.

[0098] Referring to FIG. 4, the decoding device acquires image / video information from a bitstream (S400), performs a prediction based on the acquired image / video information (S410), and can restore a picture through residual processing (S420, inverse quantization and inverse transformation of quantized transformation coefficients) (S430).

[0099] A modified restored picture can be generated by applying an in-loop filtering procedure (S440) to the restored picture generated through the above restoration procedure, and the modified restored picture can be output as a decoded picture and also stored in the buffer or memory of the decoding device to be used as a reference picture in the inter-prediction procedure when decoding the next picture. In some cases, the above in-loop filtering procedure may be omitted, in which case the restored picture can be output as a decoded picture and also stored in the buffer or memory of the decoding device to be used as a reference picture in the inter-prediction procedure when decoding a subsequent picture.

[0100] The in-loop filtering procedure (S440) may include a deblocking filtering procedure, a sample adaptive offset (SAO) procedure, an adaptive loop filter (ALF) procedure, and / or a bilateral filter procedure, and some or all of these may be omitted. Additionally, one or some of the deblocking filtering procedure, the sample adaptive offset (SAO) procedure, the adaptive loop filter (ALF) procedure, and the bilateral filter procedure may be applied sequentially, or all of them may be applied sequentially. For example, the SAO procedure may be performed after the deblocking filtering procedure is applied to the restored picture. Alternatively, for example, the ALF procedure may be performed after the deblocking filtering procedure is applied to the restored picture. This may be performed in the same manner in the encoding device.

[0101] FIG. 5 shows an example of a video / image encoding method to which an embodiment of the present disclosure can be applied.

[0102] In FIG. 5, the prediction step (S500) may be performed in the prediction unit (220) of the aforementioned encoding device (200), residual processing (S510) based on the prediction result may be performed in the residual processing unit (230), and the step (S520) of encoding image information including prediction information and residual information may be performed in the entropy encoding unit (240). S500 may include an inter / intra prediction procedure according to the present disclosure, S510 may include a residual processing procedure according to the present disclosure, and S520 may include an encoding procedure according to the present disclosure.

[0103] The encoding procedure may optionally include not only a procedure for encoding information for picture restoration (e.g., prediction information, residual information, partitioning information, etc.) and outputting it in the form of a bitstream, but also a procedure for generating a restored picture for the current picture and a procedure for applying in-loop filtering to the restored picture.

[0104] The encoding device (200) can derive (modified) residual samples from quantized transform coefficients through the inverse quantization unit (234) and the inverse transform unit (235), and can generate a restored picture based on the (modified) residual samples and the predicted samples which are the outputs of S500. The restored picture thus generated may be identical to the restored picture generated by the decoding device (300) described above. A modified restored picture may be generated through an in-loop filtering procedure on the restored picture, which may be stored in a buffer or memory, and, as in the case of the decoding device, may be used as a reference picture in the inter-prediction procedure during the subsequent encoding of the picture.

[0105] As described above, depending on the case, part or all of the in-loop filtering procedure may be omitted. When the in-loop filtering procedure is performed, (in-loop) filtering-related information (parameters) may be encoded in the entropy encoding unit (240) and output in the form of a bitstream, and the decoding device (300) may perform the in-loop filtering procedure in the same way as the encoding device based on the filtering-related information.

[0106] Through this in-loop filtering procedure, noise generated during video / image coding, such as blocking artifacts and ringing artifacts, can be reduced, and subjective / objective image quality can be improved. In addition, by performing the in-loop filtering procedure in both the encoding device (200) and the decoding device (300), the same prediction results can be derived in both the encoding device (200) and the decoding device (300), the reliability of picture coding can be increased, and the amount of data that must be transmitted for picture coding can be reduced.

[0107] As described above, the picture restoration procedure can be performed in the encoding device (200) as well as the decoding device (300). Restoration blocks can be generated based on intra prediction / inter prediction for each block unit, and a restored picture containing the restoration blocks can be generated. If the current picture / slice / tile group is an I picture / slice / tile group, the blocks included in the current picture / slice / tile group can be restored based solely on intra prediction. Meanwhile, if the current picture / slice / tile group is a P or B picture / slice / tile group, the blocks included in the current picture / slice / tile group can be restored based on intra prediction or inter prediction. In this case, inter prediction may be applied to some blocks within the current picture / slice / tile group, and intra prediction may be applied to the remaining blocks.

[0108] The color components of the picture may include a luminance component and a chroma component, and unless explicitly limited in the present disclosure, embodiments according to the present disclosure may be applied to the luminance component and the chroma component.

[0109] Figure 6 illustrates an exemplary hierarchical structure for a coded video / image.

[0110] Referring to Fig. 6, the coded image is divided into a Video Coding Layer (VCL) that handles the decoding processing of the image and the image itself, a subsystem that transmits and stores the encoded information, and a Network Abstraction Layer (NAL) that exists between the VCL and the subsystem and is responsible for network adaptation functions.

[0111] In VCL, VCL data containing compressed image data (slice data) can be generated, or parameter sets containing information such as Picture Parameter Set (PPS), Sequence Parameter Set (SPS), and Video Parameter Set (VPS), or SEI (Supplemental Enhancement Information) messages that are additionally required in the decoding process of the image can be generated.

[0112] In NAL, a NAL unit can be created by adding header information (NAL unit header) to the Raw Byte Sequence Payload (RBSP) generated in VCL. In this case, the RBSP refers to slice data, parameter sets, SEI messages, etc. generated in VCL. The NAL unit header may include NAL unit type information specified according to the RBSP data included in the NAL unit.

[0113] As shown in FIG. 6, NAL units can be classified into VCL NAL units and Non-VCL NAL units depending on the RBSP generated in VCL. A VCL NAL unit may refer to a NAL unit containing information about an image (slice data), and a Non-VCL NAL unit may refer to a NAL unit containing information necessary to decode an image (parameter set or SEI message).

[0114] The aforementioned VCL NAL unit and Non-VCL NAL unit can be transmitted over a network by attaching header information according to the data specifications of the underlying system. For example, the NAL unit can be transformed into a data format of a specified specification, such as H.266 / VVC file format, RTP (Real-time Transport Protocol), TS (Transport Stream), etc., and transmitted over various networks.

[0115] As described above, the NAL unit type can be determined according to the RBSP data structure included in the NAL unit, and information about this NAL unit type can be stored in the NAL unit header and signaled.

[0116] For example, NAL units can be broadly classified into VCL NAL unit types and Non-VCL NAL unit types depending on whether they contain information about the image (slice data). VCL NAL unit types can be classified according to the properties and types of the picture included in the VCL NAL unit, while Non-VCL NAL unit types can be classified according to the types of parameter sets.

[0117] The following is an example of a NAL unit type specified according to the type of parameter set included in the Non-VCL NAL unit type.

[0118] - APS (Adaptation Parameter Set) NAL unit: Type for the NAL unit containing the APS

[0119] - DPS(Decoding Parameter Set) NAL unit: Type for the NAL unit containing the DPS

[0120] - VPS (Video Parameter Set) NAL unit: Type for the NAL unit containing the VPS

[0121] - SPS (Sequence Parameter Set) NAL unit: Type for the NAL unit containing the SPS

[0122] - PPS(Picture Parameter Set) NAL unit: Type for the NAL unit containing the PPS

[0123] The above-described NAL unit types have syntax information for the NAL unit type, and said syntax information can be stored in the NAL unit header and signaled. For example, said syntax information may be nal_unit_type, and NAL unit types may be specified by the nal_unit_type value.

[0124] A slice header (slice header syntax, slice header information) may include information / parameters that can be commonly applied to the slice. The APS (APS syntax) or PPS (PPS syntax) may include information / parameters that can be commonly applied to one or more slices or pictures. The SPS (SPS syntax) may include information / parameters that can be commonly applied to one or more sequences. The VPS (VPS syntax) may include information / parameters that can be commonly applied to multiple layers. The DPS (DPS syntax) may include information / parameters that can be commonly applied to the entire video. The DPS may include information / parameters related to the concatenation of a CVS (coded video sequence). In the present disclosure, High Level Syntax (HLS) may include at least one of the APS syntax, PPS syntax, SPS syntax, VPS syntax, DPS syntax, or slice header syntax.

[0125] In the present disclosure, image / video information encoded by an encoding device and signaled in the form of a bitstream includes not only information related to picture partitioning, intra / inter prediction information, residual information, in-loop filtering information, etc., but may also include information included in the slice header, information included in the APS, information included in the PPS, information included in the SPS, information included in the VPS, and / or information included in the DPS.

[0126] A coded picture may consist of one or more slices. Parameters describing the coded picture are signaled within the picture header (PH), and parameters describing the slices are signaled within the slice header (SH). The PH is transmitted as its own NAL unit type. The SH is located at the beginning of the NAL unit containing the slice payload (i.e., slice data).

[0127] Hereinafter, SEI messages related to embodiments of the present disclosure will be described.

[0128] In an embodiment of the present disclosure, constituent rectangles may refer to logical units for partitioning a plurality of frame-packed video regions within a bitstream, and the size and location of each region are defined through SEI messages, and depending on the settings, may be mapped to a specific subpicture or defined as an independent region unrelated to a subpicture.

[0129] A Constituent Rectangle SEI message (hereinafter referred to as a CR SEI message) enables the composition of multiple Constituent Rectangles within a picture coded in one or more layers and provides information regarding the Constituent Rectangles, namely their ID, type, text description, location, and size. In many applications, multiple synchronized videos are required for multiview content or various types of content such as alpha channels, depth maps, object masks, and image features. Accordingly, CR SEI messages can be utilized in VR (Virtual Reality) / AR (Augmented Reality), 3D, free-viewpoint video, game streaming, cloud gaming, etc.

[0130] An example of a syntax table for CR SEI messages is shown in Table 1 below.

[0131] [Table 1]

[0132]

[0133]

[0134] The use of this CR SEI message requires the definition of the following variables:

[0135] - Picture width and picture height in luma samples, denoted as PicWidthInLumaSamples[ lId ] and PicHeightInLumaSamples[ lId ], respectively

[0136] - Maximum picture width and maximum picture height in luma samples, denoted as MaxPicWidth[ lId ] and MaxPicHeight[ lId ], respectively

[0137] - Chroma format specifier denoted as ChromaFormatIdc

[0138] - Bit depth for the sample of the chroma component, denoted as BitDepthY. If ChromaFormatIdc is not 0, it is denoted as BitDepthC as the bit depth for the sample of two associated chroma components.

[0139] - The number of subpictures indicated by NumSubpics[ lId ]

[0140] - Arrays for the top-left X and Y positions of the subpicture, denoted as SubPicTopLeftX[ lId ][ i ] and SubPicTopLeftY[ lId ][ i ], respectively

[0141] - Arrays for the width and height of the subpicture, denoted as SubPicWidth[lId][i] and SubPicHeight[lId][i], respectively

[0142] If this SEI message exists in any picture unit other than the first picture unit of the CLVS in the decoding order, a Constituent Rectangle SEI message with the same payload content must exist in the first picture unit of the CLVS in the decoding order.

[0143] If cr_444_enabled_flag is equal to 1, it indicates that the cr_group_444_flag[ i ] syntax element exists. If cr_444_enabled_flag is equal to 0, it indicates that the cr_group_444_flag[ i ] syntax element does not exist.

[0144] cr_num_layers_minus1 + 1 represents the number of layers in which a constituent rectangle is described in the SEI message.

[0145] cr_layer_id[ lIdx ] represents the layer identifier of the lIdx-th layer.

[0146] The variable lId is set to be the same as cr_layer_id[ lIdx ].

[0147] cr_num_rects_in_layer_minus1[ lIdx ] + 1 represents the number of constituent rectangles in the lIdx-th layer that are signaled in the SEI message.

[0148] The variable CrNumRects is derived as follows:

[0149] CrNumRects = 0

[0150] for( lIdx= 0; lIdx <= cr_num_layers_minus1; lIdx ++ )

[0151] CrNumRects += cr_num_rects_in_layer[ lIdx ] + 1

[0152] If cr_rect_id_enabled_flag is equal to 1, it indicates that the syntax element cr_rect_id_present_flag[ i ] is present in the SEI message. If cr_rect_id_enabled_flag is equal to 0, it indicates that the syntax element cr_rect_id_present_flag[ i ] is not present in the SEI message.

[0153] If cr_associated_rect_id_enabled_flag is equal to 1, it indicates that the syntax elements cr_associated_rect_id_present_flag[ i ] may be present in the SEI message. If cr_associated_rect_id_enabled_flag is equal to 0, it indicates that the syntax elements cr_associated_rect_id_present_flag[ i ] are not present in the SEI message.

[0154] cr_num_groups represents the maximum number of square groups described in the SEI message.

[0155] cr_rect_id_len_minus1 + 1 represents the length of the syntax elements cr_rect_id[ i ] and cr_associated_rect_id[ i ].

[0156] If cr_rect_type_enabled_flag is equal to 1, it indicates that the syntax element cr_rect_type_present_flag[ i ] is present in the SEI message. If cr_rect_type_enabled_flag is equal to 0, it indicates that the syntax element cr_rect_type_present_flag[ i ] is not present in the SEI message.

[0157] If cr_group_444_flag[ i ] is equal to 1, it indicates that the i-th 4:4:4 target picture is formed from three squares of the i-th square group. If cr_group_444_flag[ i ] is equal to 0, it indicates that the 4:4:4 picture is not formed from the squares of the i-th square group.

[0158] If cr_colour_description_present_flag[ i ] is equal to 1, it indicates that the syntax elements cr_colour_primaries[ i ], cr_transfer_characteristics[ i ], cr_matrix_coeffs[ i ] and cr_full_range_flag[ i ] exist. If cr_colour_description_present_flag[ i ] is equal to 0, it indicates that the above syntax elements do not exist.

[0159] cr_colour_primaries[ i ] has the same semantics as defined for the vui_colour_primaries syntax element, but applies to the i-th target picture. If it does not exist, the value of cr_colour_primaries[ i ] is inferred to be the same as the value of vui_colour_primaries.

[0160] cr_transfer_characteristics[ i ] has the same semantics as defined for the vui_transfer_characteristics syntax element, but applies to the i-th target picture. If it does not exist, the value of cr_transfer_characteristics[ i ] is inferred to be the same as the value of vui_transfer_characteristics.

[0161] cr_matrix_coeffs[ i ] has the same semantics as defined for the vui_matrix_coeffs syntax elements, but applies to the i-th target picture. If it does not exist, the value of cr_matrix_coeffs[ i ] is inferred to be the same as the value of vui_matrix_coeffs.

[0162] cr_full_range_flag[ i ] has the same semantics as defined for the vui_full_range_flag syntax element, but applies to the i-th target picture. If it does not exist, the value of cr_full_range_flag[ i ] is inferred to be the same as the value of vui_full_range_flag.

[0163] If cr_rect_type_descriptions_enabled_flag is equal to 1, it indicates that the syntax element cr_rect_type_description_present_flag[ i ] is present in the SEI message. If cr_rect_type_descriptions_enabled_flag is equal to 0, it indicates that the syntax element cr_rect_type_description_present_flag[ i ] is not present in the SEI message.

[0164] cr_subpics_partitioning_flag[ lIdx ] indicates whether subpicture partitioning parameters within the SPS associated with the lIdx-th layer are used to determine the size and position of the constituent rectangle. That is, cr_subpics_partitioning_flag[ lIdx ] may be information indicating whether the constituent rectangle is partitioned or derived based on the subpicture.

[0165] If cr_subpics_partitioning_flag[ lIdx ] is equal to 1, it indicates that the subpicture partitioning parameters within the SPS associated with the lIdx-th layer are used to determine the size and position of the constituent rectangle. If cr_subpics_partitioning_flag[ lIdx ] is equal to 0, it indicates that the determination of the size and position of the constituent rectangle is not based on the subpicture partitioning parameters within the SPS.

[0166] If cr_subpics_partitioning_flag is equal to 1, the bitstream conformance requirement is that NumSubpics must be greater than or equal to cr_num_rects_minus1 + 1.

[0167] cr_rect_same_size_flag[ lIdx ] indicates whether all constituent rectangles within the coded picture of the lIdx-th layer have the same size and are arranged in a grid pattern.

[0168] If cr_rect_same_size_flag[ lIdx ] is equal to 1, it indicates that all constituent rectangles within the coded picture of the lIdx-th layer have the same size and are arranged in a grid pattern. If cr_rect_same_size_flag[ lIdx ] is equal to 0, it indicates that the sizes of the constituent rectangles may differ.

[0169] cr_num_cols_minus1[ lIdx ] + 1 and cr_num_rows_minus1[ lIdx ] + 1 represent the number of columns and rows, respectively, of the constituent rectangle grid within the coded picture of the lIdx-th layer, where cr_rect_same_size_flag is equal to 1. The values ​​of cr_num_cols_minus1[ lIdx ] and cr_num_rows_minus1[ lIdx ] must be within the range (inclusive) of 0 to 4095.

[0170] The variable crNumCols[ lIdx ] is set to be equal to cr_num_cols_minus1[ lIdx ] + 1.

[0171] The variable crNumRows[ lIdx ] is set to be equal to cr_num_rows_minus1[ lIdx ] + 1.

[0172] The bitstream conformance requirement is that if cr_rect_same_size_flag[ lIdx ] exists and is equal to 1, then crNumCols[ lIdx ] Х crNumRows[ lIdx ] must be equal to cr_num_rects_in_layer_minus1[ lIdx ] + 1.

[0173] cr_guardband_hor_size_minus1[ lIdx ] + 1 specifies the size of the horizontal guardband between the constituent rectangles within the coded picture of the lIdx-th layer in luminance samples, where cr_rect_same_size_flag is equal to 1.

[0174] The variable GuardbandHor[ lIdx ] is set to cr_guardband_hor_size_minus1[ lIdx ] + 1 if cr_guardbands_present_flag[ lIdx ] is true, and to 0 otherwise.

[0175] The requirement for bitstream conformity is that GuardbandHor[ lIdx ] % SubWidthC must be equal to 0.

[0176] cr_guardband_ver_size_minus1[ lIdx ] + 1 specifies the size of the vertical guardband between constituent rectangles in luminance samples when cr_rect_same_size_flag is equal to 1.

[0177] The variable GuardbandVer[ lIdx ] is set to cr_guardband_ver_size_minus1[ lIdx ] + 1 if cr_guardbands_present_flag[ lIdx ] is true, and to 0 otherwise.

[0178] The requirement for bitstream conformity is that GuardbandVer[ lIdx ] % SubHeightC must be equal to 0.

[0179] cr_log2_unit_size[ lIdx ] specifies the unit size used for variable calculations for the constituent rectangle parameters of the lIdx-th layer.

[0180] The variable crUnitSize[ lIdx ] is set to be equal to 1 << cr_log2_unit_size[ lIdx ].

[0181] cr_rect_size_len_minus1[ lIdx ] + 1 represents the lengths of the syntax elements cr_rect_top_left_in_units_x[ lIdx ][ i ], cr_rect_top_left_in_units_y[ lIdx ][ i ], cr_rect_width_in_units_minus1[ lIdx ][ i ] and cr_rect_height_in_units_minus1[ lIdx ][ i ].

[0182] If cr_rect_type_present_flag[ i ] is equal to 1, it indicates that the cr_rect_type_idc[ i ] syntax element exists in the SEI message. If cr_rect_type_present_flag[ i ] is equal to 0, it indicates that the cr_rect_type_idc[ i ] syntax element does not exist in the SEI message.

[0183] cr_rect_type_idc[ i ] represents the constituent picture type of the i-th constituent rectangle according to Table 2. If it does not exist and i is equal to 0, the value of cr_rect_type_idc[ i ] is inferred to be equal to 0. If cr_rect_type_idc[ i ] does not exist and i is greater than 0, cr_rect_type_idc[ i ] is inferred to be equal to cr_rect_type_idc[ i - 1 ].

[0184] The mapping relationship of cr_rect_type_idc[ i ] to the types of constituent rectangles is as shown in Table 2 below.

[0185] [Table 2]

[0186]

[0187] For convenience of notation and terminology in this specification, variables and terms associated with color components are referred to as luma (or L or Y) and chroma, regardless of the color representation method actually used, and the two chroma arrays are referred to as Cb and Cr. The color representation method actually used may be indicated in this SEI message or the VUI SEI message.

[0188] If cr_rect_id_present_flag[ i ] is equal to 1, it indicates that the cr_rect_id[ i ] syntax element exists in the SEI message. If cr_rect_id_present_flag[ i ] is equal to 0, it indicates that the cr_rect_id[ i ] syntax element does not exist in the SEI message.

[0189] cr_rect_id[i] represents the ID of the i-th rectangle. The length of the corresponding syntax element is cr_rect_id_len_minus1 + 1 bit. If the corresponding syntax element does not exist and i is equal to 0, the value of cr_rect_id[i] is inferred to be equal to 0. If the corresponding syntax element does not exist and i is greater than 0, the value of cr_rect_id[i] is inferred to be equal to cr_rect_id[i - 1] + 1. The requirement of bitstream conformance is that if j is not equal to k, cr_rect_id[j] must not be equal to cr_rect_id[k].

[0190] If cr_associated_rect_id_present_flag[ i ] is equal to 1, it indicates that the cr_associated_rect_id[ i ] syntax element exists in the SEI message. If cr_associated_rect_id_present_flag[ i ] is equal to 0, it indicates that the cr_associated_rect_id[ i ] syntax element does not exist in the SEI message.

[0191] cr_associated_rect_id[ i ] represents the ID of the primary rectangle associated with the i-th rectangle. The length of the corresponding syntax element is cr_rect_id_len_minus1 + 1 bit.

[0192] The primary rectangle is a constituent rectangle with cr_rect_type_idc equal to 0.

[0193] The bitstream conformance requirement is that if cr_associated_rect_id[ i ] exists, the value of cr_associated_rect_id[ i ] must be equal to cr_rect_id[ j ] for any value j in the range from 0 to CrNumRects - 1 (inclusive), and cr_rect_type_idc[ j ] must not be equal to 255.

[0194] If cr_associated_rect_id[ i ] does not exist, the value of cr_associated_rect_id[ i ] is undefined.

[0195] cr_rect_group_id[ i ] represents the group ID of the i-th rectangle. The length of the corresponding syntax element is Ceil(Log2(cr_num_groups)) bits. If the corresponding syntax element does not exist and cr_rect_type_idc[ i ] is not equal to 255, the value of cr_rect_group_id[ i ] is inferred to be equal to 0.

[0196] The requirement for bitstream conformance is that if cr_rect_type_idc[ i ] is in the range of 4 to 6, cr_group_444_flag[ cr_rect_group_id[ i ] ] must be equal to 1.

[0197] If j is in the range from 0 to cr_num_groups - 1 and cr_group_444_flag[ j ] is equal to 1, the following applies:

[0198] - The requirement for bitstream conformance is that there exists some value y within the range of 0 to cr_num_rects_minus1 such that cr_rect_group_id[ y ] is equal to j and cr_rect_type_idc[ y ] is equal to 0 or 4.

[0199] - The requirement for bitstream conformity is that there exists some value u within the range of 0 to cr_num_rects_minus1 such that cr_rect_group_id[ u ] is equal to j and cr_rect_type_idc[ u ] is equal to 5.

[0200] - The requirement for bitstream conformity is that there exists some value v in the range from 0 to cr_num_rects_minus1 such that cr_rect_group_id[ v ] is equal to j and cr_rect_type_idc[ v ] is equal to 6.

[0201] - The values ​​of cr_rect_width_in_units_minus1[ y ], cr_rect_width_in_units_minus1[ u ] and cr_rect_width_in_units_minus1[ v ] must be identical.

[0202] - The values ​​of cr_rect_height_in_units_minus1[ y ], cr_rect_height_in_units_minus1[ u ] and cr_rect_height_in_units_minus1[ v ] must be identical.

[0203] - The j-th target picture is created with a width of cr_rect_width_in_units_minus1[ y ], a height of cr_rect_height_in_units_minus1[ y ], SubWidthC of 1, SubHeightC of 1, and ChromaFormatIdc of 3, with the luminance sample set to the luminance sample of the y-th rectangle, the Cb sample set to the luminance sample of the u-th rectangle, and the Cr sample set to the luminance sample of the v-th rectangle.

[0204] If cr_rect_type_description_present_flag[ i ] is equal to 1, it indicates that the cr_rect_type_description[ i ] syntax element exists in the SEI message. If cr_rect_type_description_present_flag[ i ] is equal to 0, it indicates that the cr_rect_type_description[ i ] syntax element does not exist in the SEI message. If cr_rect_type_description_present_flag[ i ] does not exist, the value of cr_rect_type_description_present_flag[ i ] is inferred to be equal to 0.

[0205] cr_rect_top_left_in_units_x[ lIdx ][ i ] and cr_rect_top_left_in_units_y[ lIdx ][ i ], if present, represent the horizontal and vertical positions of the top-left position of the i-th constituent rectangle within the lIdx-th layer picture in units, respectively. The length of the corresponding syntax elements is cr_rect_size_len_minus1[ lIdx ] + 1. In this disclosure, "lIdx-th" may mean having an index value of lIdx, and "i-th" may mean having an index value of i.

[0206] The variables SubWidthC and SubHeightC are derived from ChromaFormatIdc.

[0207] cr_rect_width_in_units_minus1[ lIdx ][ i ] + 1 and cr_rect_height_in_units_minus1[ lIdx ][ i ] + 1 represent the width and height, respectively, of the i-th constituent rectangle within the lIdx-th layer picture, in units, where these syntax elements exist. The length of these syntax elements is cr_rect_size_len_minus1 + 1.

[0208] The variables crRectTopLeftX[ lIdx ][ i ] and crRectTopLeftY[ lIdx ][ i ], representing the x and y positions of the i-th constituent rectangle, respectively, and the variables crRectWidth[ lIdx ][ i ] and crRectHeight[ lIdx ][ i ], representing the width and height, respectively, are derived as follows.

[0209] If cr_subpics_partitioning_flag is equal to 0 and cr_rect_same_size_flag is equal to 0, the following applies:

[0210] - crRectTopLeftX[ lIdx ][ i ] is set to be the same as cr_rect_top_left_in_units_x[ lIdx ][ i ] * crUnitSize[ lIdx ].

[0211] - crRectTopLeftY[ lIdx ][ i ] is set to be the same as cr_rect_top_left_in_units_y[ lIdx ][ i ] * crUnitSize[ lIdx ].

[0212] - crRectWidth[ lIdx ][ i ] is set to be equal to (cr_rect_width_in_units_minus1[ lIdx ][ i ] + 1) * crUnitSize[ lIdx ].

[0213] - crRectHeight[ lIdx ][ i ] is set to be equal to (cr_rect_height_in_units_minus1[ lIdx ][ i ] + 1) * crUnitSize[ lIdx ].

[0214] Otherwise, if cr_subpics_partitioning_flag is equal to 1, the following applies:

[0215] - crRectTopLeftX[ lIdx ][ i ] is set to be the same as SubPicTopLeftX[ lIdx ][ i ].

[0216] - crRectTopLeftY[ lIdx ][ i ] is set to be the same as SubPicTopLeftY[ lIdx ][ i ].

[0217] - crRectWidth[ lIdx ][ i ] is set to be the same as SubPicWidth[ lIdx ][ i ].

[0218] - crRectHeight[ lIdx ][ i ] is set to be the same as SubPicHeight[ lIdx ][ i ].

[0219] Otherwise (i.e., if cr_rect_same_size_flag is equal to 1), the following applies:

[0220] - The variable currRow[ lIdx ] is set to be the same as i % crNumCols[ lIdx ].

[0221] - The variable currCol[ lIdx ] is set to be the same as i / crNumCols[ lIdx ].

[0222] - crRectWidth[ lIdx ][ i ] is set to be the same as (MaxPicWidth[ lId ] - GuardbandHor[ lIdx ] * (crNumCols[ lIdx ] - 1)) / crNumCols[ lIdx ].

[0223] - crRectHeight[ lIdx ][ i ] is set to be the same as (MaxPicHeight[ lId ] - GuardbandVer[ lIdx ] * (crNumRows[ lIdx ] - 1)) / crNumRows[ lIdx ].

[0224] - crRectTopLeftX[ lIdx ][ i ] is set to be the same as currCol[ lIdx ] * (crRectWidth[ lIdx ][ i ] + GuardbandHor[ lIdx ]).

[0225] - crRectTopLeftY[ lIdx ][ i ] is set to be the same as currRow[ lIdx ] * (crRectHeight[ lIdx ][ i ] + GuardbandVer[ lIdx ]).

[0226] If PicWidthInLumaSamples[ lId ] is not equal to MaxPicWidth[ lId ], the following applies:

[0227] - crRectTopLeftX[ lIdx ][ i ] is set to be the same as (crRectTopLeftX[ lIdx ][ i ] * PicWidthInLumaSamples[ lId ] + MaxPicWidth[ lId ] / 2) / MaxPicWidth[ lId ].

[0228] - crRectWidth[ lIdx ][ i ] is set to be the same as (crRectWidth[ lIdx ][ i ] * PicWidthInLumaSamples[ lId ] + MaxPicWidth[ lId ] / 2) / MaxPicWidth[ lId ].

[0229] If PicHeightInLumaSamples[ lId ] is not equal to MaxPicHeight[ lId ], the following applies:

[0230] - crRectTopLeftY[ lIdx ][ i ] is set to be the same as (crRectTopLeftY[ lIdx ][ i ] * PicHeightInLumaSamples[ lId ] + MaxPicHeight[ lId ] / 2) / MaxPicHeight[ lId ].

[0231] - crRectHeight[ lIdx ][ i ] is set to be equal to (crRectHeight[ lIdx ][ i ] * PicHeightInLumaSamples[ lId ] + MaxPicHeight[ lId ] / 2) / MaxPicHeight[ lId ].

[0232] The requirement of bitstream suitability is that for each sample position (x, y) within the coded picture, there must be at most exactly one rectangle j satisfying all of the following conditions:

[0233] - x is within the range of (crRectTopLeftX[ lIdx ][ j ] .. crRectTopLeftX[ lIdx ][ j ] + crRectWidth[ lIdx ][ j ] - 1).

[0234] - y is within the range of (crRectTopLeftY[ lIdx ][ j ] .. crRectTopLeftY[ lIdx ][ j ] + crRectHeight[ lIdx ][ j ] - 1).

[0235] The requirement for bitstream conformity is that crRectWidth[ lIdx ][ i ] and crRectHeight[ lIdx ][ i ] must be greater than 0.

[0236] The bitstream conformity requirement is that crRectTopLeftX[ lIdx ][ i ] + crRectWidth[ lIdx ][ i ] must be less than or equal to MaxPicWidth[ lId ], and crRectTopLeftY[ lIdx ][ i ] + crRectHeight[ lIdx ][ i ] must be less than or equal to MaxPicHeight[ lId ].

[0237] The bitstream conformance requirement is that crRectTopLeftX[ lIdx ][ i ] % SubWidthC must be equal to 0, crRectTopLeftY[ lIdx ][ i ] % SubHeightC must be equal to 0, crRectWidth[ lIdx ][ i ] % SubWidthC must be equal to 0, and crRectHeight[ lIdx ][ i ] % SubHeightC must be equal to 0.

[0238] cr_bit_equal_to_zero must be equal to 0.

[0239] cr_rect_type_description[ i ] represents a text description for a constituent rectangle. The length of the syntax element must be 4097 bytes or less, excluding the null termination byte.

[0240] In the current design of CR SEI messages, constituent rectangles belonging to a specific layer may or may not be derived or segmented based on sub-pictures. When constituent rectangles are derived from sub-pictures, the following issues exist in the current design:

[0241] In the current constraints regarding the number of constituent rectangles and subpictures, a variable representing the total number of constituent rectangles is used. However, this constraint should be based solely on the number of subpictures within a specific layer. In other words, the constraint should be established based on the number of subpictures associated with the number of constituent rectangles from a specific layer; however, it is inaccurate because a variable representing the total number of constituent rectangles is used.

[0242] In the current design, if the number of constituent rectangles from a specific layer is less than the number of subpictures contained in that layer, only the first set of subpictures corresponding to the number of constituent rectangles from that layer can be described or used in the CR SEI message. It is desirable to allow specifying the index of the corresponding subpicture for each constituent rectangle.

[0243] To address these problems, the present disclosure proposes the following embodiments or examples. Each embodiment or example may be applied individually or two or more may be applied in combination:

[0244] - When cr_subpics_partitioning_flag[ lIdx ] is equal to 1, it specifies that the number of subpictures included in the layer must be equal to or greater than the number of constituent rectangles from that layer.

[0245] - As an alternative, when cr_subpics_partitioning_flag[ lIdx ] is equal to 1, specify that the number of constituent rectangles from that layer must be equal to the number of subpictures contained in that layer.

[0246] - When cr_subpics_partitioning_flag[ lIdx ] is equal to 1, for each constituent rectangle belonging to the layer, signal an index to reference the index of the subpicture associated with that constituent rectangle.

[0247] Each embodiment or example is described in detail below.

[0248] First, cr_subpics_partitioning_flag[ lIdx ] is a syntax element, which is information indicating whether the subpicture partitioning parameter included in the SPS associated with the lIdx-th layer is used to determine the size and position of the constituent rectangle.

[0249] A cr_subpics_partitioning_flag[ lIdx ] equal to 1 indicates that the subpicture partitioning parameter included in the SPS associated with the lIdx-th layer is used to determine the size and position of the constituent rectangle.

[0250] A cr_subpics_partitioning_flag equal to 0 indicates that the determination of the size and position of the constituent rectangle is not based on the subpicture partitioning parameters included in the SPS.

[0251] Conventionally, as a requirement for bitstream conformity, it was specified that when cr_subpics_partitioning_flag is equal to 1, NumSubpics must be greater than or equal to cr_num_rects_minus1 + 1. That is, when constituent rectangles are derived or partitioned based on subpictures, it was specified that the number of subpictures must be greater than or equal to the number of constituent rectangles. In other words, when the subpicture partitioning parameter included in the SPS associated with the lIdx-th layer is used to determine the size and position of constituent rectangles, it was specified that the number of subpictures must be greater than or equal to the number of constituent rectangles. Here, the number of constituent rectangles represented by cr_num_rects_minus1 + 1 is the total number of constituent rectangles, not the number of constituent rectangles from a specific layer. Therefore, a problem may arise where the constraints related to the number of composition rectangles and subpictures become inaccurate.

[0252] According to one embodiment, when cr_subpics_partitioning_flag is equal to 1, NumSubpics can be greater than or equal to cr_num_rects_in_layer_minus1 [ lIdx ] + 1, thereby changing the constraint, that is, the requirement for bitstream consistency. That is, when a constituent rectangle is derived from a subpicture, or when a constituent rectangle is partitioned based on a subpicture, the number of subpictures must be greater than or equal to the number of constituent rectangles within a specific layer. In other words, when a subpicture partitioning parameter included in the SPS associated with the layer having index value lIdx is used to determine the size and position of the constituent rectangle, the number of subpictures must be greater than or equal to the number of constituent rectangles within the layer having index value lIdx. As a result, constraints related to the number of composition rectangles and subpictures become accurate, and errors during the coding process can be prevented.

[0253] As another example, when cr_subpics_partitioning_flag is equal to 1, NumSubpics can be changed to cr_num_rects_in_layer_minus1 [ lIdx ] + 1, which means the constraints, or requirements for bitstream consistency, can be modified. That is, when a constituent rectangle originates from a subpicture, or when a constituent rectangle is based on a subpicture, the number of subpictures must be equal to the number of constituent rectangles within a specific layer. In other words, if the subpicture partitioning parameter included in the SPS associated with the lIdx-th layer is used to determine the size and position of the constituent rectangle, the number of subpictures must be equal to the number of constituent rectangles within the lIdx-th layer. This ensures that the constraints related to the number of constituent rectangles and subpictures are accurate and prevents errors during the coding process.

[0254] To signal an index to reference the index of a subpicture associated with a constituent rectangle, the syntax can be modified as shown in Table 3 below.

[0255] [Table 3]

[0256]

[0257] Referring to Table 3 above, when cr_subpics_partitioning_flag[ lIdx ] is true, for example, when its value is 1, cr_subpic_idx[ lIdx ][ crIdx ] can be signaled / parsed. That is, when defining the index of a subpicture of a specific layer (the lIdx-th layer), the index of the subpicture can be defined by the constituent rectangle by considering the index of the constituent rectangle together.

[0258] If cr_subpic_idx[ lIdx ][ crIdx ] exists, it specifies the index of the subpicture associated with the i-th Constituent Rectangle unit among the subpictures belonging to the lIdx-th layer. The value of cr_subpic_idx[ lIdx ][ crIdx ] is within the range from 0 to NumSubpics[ cr_layer_id[ lIdx ] ]. That is, the value of the subpicture index associated with the constituent rectangle is within the range from 0 to the number of subpictures of the layer having the index value of lIdx.

[0259] cr_rect_top_left_in_units_x[ lIdx ][ i ] and cr_rect_top_left_in_units_y[ lIdx ][ i ], if present, represent the horizontal and vertical positions in units of the top-left position of the i-th constituent rectangle within the lIdx-th layer picture, respectively. The length of these syntax elements is cr_rect_size_len_minus1[ lIdx ] + 1.

[0260] The variables SubWidthC and SubHeightC are derived from ChromaFormatIdc.

[0261] cr_rect_width_in_units_minus1[ lIdx ][ i ] + 1 and cr_rect_height_in_units_minus1[ lIdx ][ i ] + 1 represent, respectively, the width and height in units of the i-th constituent rectangle within the lIdx-th layer picture, if present. The length of the corresponding syntax elements is cr_rect_size_len_minus1 + 1.

[0262] The variables crRectTopLeftX[ lIdx ][ i ] and crRectTopLeftY[ lIdx ][ i ], representing the x and y positions of the i-th constituent rectangle, respectively, and the variables crRectWidth[ lIdx ][ i ] and crRectHeight[ lIdx ][ i ], representing the width and height, respectively, are derived as follows.

[0263] If cr_subpics_partitioning_flag is equal to 0 and cr_rect_same_size_flag is equal to 0, the following applies:

[0264] - The variable crRectTopLeftX[ lIdx ][ i ] is set to be equal to cr_rect_top_left_in_units_x[ lIdx ][ i ] * crUnitSize[ lIdx ].

[0265] - The variable crRectTopLeftY[ lIdx ][ i ] is set to be equal to cr_rect_top_left_in_units_y[ lIdx ][ i ] * crUnitSize[ lIdx ].

[0266] - The variable crRectWidth[ lIdx ][ i ] is set to equal ( cr_rect_width_in_units_minus1[ lIdx ][ i ] + 1 ) * crUnitSize[ lIdx ].

[0267] - The variable crRectHeight[ lIdx ][ i ] is set to equal ( cr_rect_height_in_units_minus1[ lIdx ][ i ] + 1 ) * crUnitSize[ lIdx ].

[0268] Otherwise, if cr_subpics_partitioning_flag is equal to 1, the following applies:

[0269] - The variable crRectTopLeftX[ lIdx ][ i ] is set to be equal to SubPicTopLeftX[ lIdx ][ cr_subpic_idx[ lIdx ][ crIdx ] ].

[0270] - The variable crRectTopLeftY[ lIdx ][ i ] is set to be equal to SubPicTopLeftY[ lIdx ][ cr_subpic_idx[ lIdx ][ crIdx ] ].

[0271] - The variable crRectWidth[ lIdx ][ i ] is set to be equal to SubPicWidth[ lIdx ][ cr_subpic_idx[ lIdx ][ crIdx ] ].

[0272] - The variable crRectHeight[ lIdx ][ i ] is set to be equal to SubPicHeight[ lIdx ][ cr_subpic_idx[ lIdx ][ crIdx ] ].

[0273] In other words, when setting variables, the accuracy of the coding can be improved by setting them to be equal to the values ​​of SubPicTopLeftX[ lIdx ], SubPicTopLeftY[ lIdx ], SubPicWidth[ lIdx ], and SubPicHeight[ lIdx ] for each cr_subpic_idx[ lIdx ][ crIdx ].

[0274] As another example, the syntax can be changed as shown in Table 4 below.

[0275] [Table 4]

[0276]

[0277]

[0278] Referring to Table 4 above, the CR SEI message may include cr_subpic_idx_enabled_flag. cr_subpic_idx_enabled_flag may be a flag, syntax element, or information indicating whether the syntax element cr_subpic_idx_len_minus1 exists in the CR SEI message.

[0279] A cr_subpic_idx_enabled_flag equal to 1 indicates that the syntax element cr_subpic_idx_len_minus1 exists in the CR SEI message. Therefore, when cr_subpic_idx_enabled_flag is 1, cr_subpic_idx_len_minus1 can be signaled / parsed. A cr_subpic_idx_enabled_flag equal to 0 indicates that the syntax element cr_subpic_idx_len_minus1 does not exist in the SEI message.

[0280] cr_subpic_idx_len_minus1 + 1 represents the length of cr_subpic_idx[ lIdx ][ crIdx ].

[0281] cr_subpic_idx[ lIdx ][ crIdx ] may be information or syntax elements that specify the index of a subpicture belonging to the lIdx-th layer for each constituent rectangle. That is, cr_subpic_idx[ lIdx ][ crIdx ], if present, specifies the index of the subpicture associated with the i-th constituent rectangle unit among the subpictures belonging to the lIdx-th layer. The number of bits to signal cr_subpic_idx[ lIdx ][ crIdx ] is cr_subpic_idx_len_minus1 + 1. If cr_subpic_idx[ lIdx ][ crIdx ] does not exist, the value of cr_subpic_idx[ lIdx ][ crIdx ] is inferred as crIdx.

[0282] As described in Table 4 above, when cr_subpics_partitioning_flag[ lIdx ] is true (e.g., when it is 1), if the value of cr_subpic_idx_enabled_flag is true (e.g., when it is 1), cr_subpic_idx[ lIdx ][ crIdx ] can be signaled / parsed.

[0283] In this way, by allowing the index of the corresponding subpicture to be specified for each constituent rectangle, more accurate coding is made possible.

[0284] FIG. 7 is a diagram illustrating a method for encoding image information according to one embodiment.

[0285] The method according to one embodiment may be performed by an encoding device (200) according to one embodiment. Accordingly, all or part of the description of the encoding device (200) described above and the description of the encoding method described with reference to FIG. 5 may also be applied to the method according to one embodiment. That is, the descriptions described above may also be applied to the method according to one embodiment to the extent that they do not conflict with the descriptions described below.

[0286] The encoding device (200) may include a memory and a processor electrically connected to the memory, and the operation of the aforementioned encoding device (200), the encoding method, or the method described below may be executed by the processor of the encoding device (200).

[0287] Terms or names used in this disclosure (e.g., names of syntax elements or names of variables, etc.) are merely examples, and the scope of the embodiments is not limited to these terms. Even if a term is not used in this disclosure, if substantial features such as the function performed, the definition thereof, or the method by which it is derived are identical or similar to those of this disclosure, it may be considered to be included within the scope of the embodiments described in this disclosure.

[0288] In addition, the method according to one embodiment may include other operations in addition to the operations described below, and some of the operations described below may be omitted depending on the example.

[0289] Referring to FIG. 7, a method for encoding image information according to one embodiment may include the step (S1010) of generating a CR-related message for identifying a subpicture associated with each of at least one constituent rectangles for a specific layer among at least one layer, and the step (S1020) of encoding image information including the CR-related message.

[0290] For example, a CR-related message generated according to the method of FIG. 7 may include some or all of the syntax of the aforementioned Table 4. Accordingly, the CR-related message described in step S1010 may be the CR SEI message described in Table 4, and the contents described above with reference to Table 4 may also be applied to this embodiment.

[0291] The above CR-related message may include subpicture index information representing a subpicture associated with each constituent rectangle for the above specific layer. In this disclosure, "specific layer" is an expression used to refer to the same layer.

[0292] The subpicture associated with each of the above-mentioned constituent rectangles may belong to the specific layer. For example, if at least one constituent rectangle is a constituent rectangle belonging to the lIdx-th layer, the subpicture associated with that constituent rectangle may also be a subpicture belonging to the same layer. In other words, if at least one constituent rectangle is a constituent rectangle belonging to the layer having the index value lIdx, the subpicture associated with that constituent rectangle may also be a subpicture belonging to the layer having the same index value.

[0293] For example, subpicture index information may correspond to the syntax element cr_subpic_idx[lIdx][crIdx] of Table 4 described above. cr_subpic_idx[ lIdx ][ crIdx ] may be information or a syntax element that specifies the index of a subpicture belonging to the lIdx-th layer for each constituent rectangle. That is, cr_subpic_idx[ lIdx ][ crIdx ], if present, specifies the index of a subpicture associated with the i-th constituent rectangle unit among the subpictures belonging to the lIdx-th layer. Here, the i-th constituent rectangle may refer to the i-th constituent rectangle among all constituent rectangles.

[0294] Alternatively, cr_subpic_idx[ lIdx ][ crIdx ] specifies the index of the subpicture associated with the crIdx-th CR among the composition rectangles belonging to the lIdx-th layer among the subpictures belonging to the lIdx-th layer. The number of bits to signal cr_subpic_idx[ lIdx ][ crIdx ] is cr_subpic_idx_len_minus1 + 1.

[0295] The above CR-related message may include index length information representing information related to the length of the above subpicture index information. The above index length information may correspond to the syntax element cr_subpic_idx_len_minus1 among the syntaxes of Table 4. cr_subpic_idx_len_minus1 + 1 may represent the length of cr_subpic_idx[ lIdx ][ crIdx ].

[0296] The above CR-related message may include subpicture index availability information indicating whether the index length information is included in the above CR-related message. The above subpicture index availability information may correspond to the syntax element cr_subpic_idx_enabled_flag among the syntaxes of Table 4. cr_subpic_idx_enabled_flag may indicate whether the syntax element cr_subpic_idx_len_minus1 exists in the CR SEI message. A cr_subpic_idx_enabled_flag equal to 1 indicates that the syntax element cr_subpic_idx_len_minus1 exists in the CR SEI message. Therefore, when cr_subpic_idx_enabled_flag is 1, the encoding device (200) may signal cr_subpic_idx_len_minus1. A cr_subpic_idx_enabled_flag equal to 0 indicates that the syntax element cr_subpic_idx_len_minus1 does not exist in the SEI message.

[0297] The above CR-related message may include CR partitioning information indicating whether the constituent rectangle is derived based on subpictures. The CR partitioning information may correspond to the syntax element cr_subpics_partitioning_flag[ lIdx ] among the syntaxes of Table 4. cr_subpics_partitioning_flag[ lIdx ] is information indicating whether the subpicture partitioning parameter included in the SPS associated with the lIdx-th layer is used to determine the size and position of the constituent rectangle. When cr_subpics_partitioning_flag[ lIdx ] is equal to 1, it indicates that the subpicture partitioning parameter included in the SPS associated with the lIdx-th layer is used to determine the size and position of the constituent rectangle. A cr_subpics_partitioning_flag equal to 0 indicates that the determination of the size and position of the constituent rectangle is not based on the subpicture partitioning parameters included in the SPS.

[0298] The above subpicture index information may be included in the CR-related message based on the fact that the value of the CR partitioning information is 1 and the value of the subpicture index availability information is 1. In other words, the encoding device (200) may signal cr_subpic_idx[ lIdx ][ crIdx ] when cr_subpics_partitioning_flag[ lIdx ] is true (e.g., when it is 1) and the value of cr_subpic_idx_enabled_flag is 1 (e.g., when it is 1). That is, when cr_subpics_partitioning_flag[ lIdx ] is true (e.g., when it is 1) and cr_subpic_idx_enabled_flag is true (e.g., when it is 1), the subpicture index information may be included in the CR-related message.

[0299] A bitstream is generated based on video information encoded according to the method described above, and the bitstream can be stored non-transiently on a computer-readable storage medium.

[0300] Additionally, a method for transmitting a bitstream according to one embodiment may include the step of generating a bitstream and the step of transmitting data including said bitstream. Here, the bitstream may be generated based on the method described above.

[0301] In addition, this transmission method may be performed by a transmission device comprising at least one processor and a transmission unit. The processor of the transmission device may generate a bitstream based on the aforementioned method, and the generated bitstream may be transmitted through the transmission unit.

[0302] FIG. 8 is a diagram illustrating a method for decoding image information according to one embodiment.

[0303] A method according to one embodiment may be performed by a decoding device (300) according to one embodiment. Accordingly, all or part of the description of the decoding device (300) described above and the description of the decoding method described with reference to FIG. 4 may also be applied to a method according to one embodiment. That is, the descriptions described above may also be applied to a method according to one embodiment to the extent that they do not conflict with the descriptions described below.

[0304] The decoding device (300) may include a memory and a processor electrically connected to the memory, and the operation of the decoding device (300) described above, the decoding method, or the method described below may be executed by the processor of the decoding device (300).

[0305] Terms or names used in this disclosure (e.g., names of syntax elements or names of variables, etc.) are merely examples, and the scope of the embodiments is not limited to these terms. Even if a term is not used in this disclosure, if substantial features such as the function performed, the definition thereof, or the method by which it is derived are identical or similar to those of this disclosure, it may be considered to be included within the scope of the embodiments described in this disclosure.

[0306] In addition, the method according to one embodiment may include other operations in addition to the operations described below, and some of the operations described below may be omitted depending on the example.

[0307] Referring to FIG. 8, a method for decoding image information according to one embodiment may include the step of obtaining image information including a CR-related message from a bitstream (S1110) and the step of identifying a subpicture associated with each of at least one constituent rectangles belonging to a specific layer among at least one layer based on the CR-related message.

[0308] For example, the CR-related message obtained according to the method of FIG. 8 may include some or all of the syntax of the aforementioned Table 4. Accordingly, the CR-related message described in step S1110 may be the CR SEI message described in Table 4, and the contents described above with reference to Table 4 may also be applied to this embodiment.

[0309] The above CR-related message may include subpicture index information representing a subpicture associated with each constituent rectangle for the above specific layer.

[0310] The subpicture associated with each of the above-mentioned constituent rectangles may be a subpicture belonging to the specific layer. For example, if at least one constituent rectangle is a constituent rectangle belonging to the lIdx-th layer, the subpicture associated with that constituent rectangle may also be a subpicture belonging to the same layer. In other words, if at least one constituent rectangle is a constituent rectangle belonging to the layer having the index value lIdx, the subpicture associated with that constituent rectangle may also be a subpicture belonging to the layer having the same index value.

[0311] For example, subpicture index information may correspond to the syntax element cr_subpic_idx[lIdx][crIdx] of Table 4 described above. cr_subpic_idx[ lIdx ][ crIdx ] may be information or a syntax element that specifies the index of a subpicture belonging to the lIdx-th layer for each constituent rectangle. That is, cr_subpic_idx[ lIdx ][ crIdx ], if present, specifies the index of a subpicture associated with the i-th constituent rectangle unit among the subpictures belonging to the lIdx-th layer. Here, the i-th constituent rectangle may refer to the i-th constituent rectangle among all constituent rectangles.

[0312] Alternatively, cr_subpic_idx[ lIdx ][ crIdx ] specifies the index of the subpicture associated with the crIdx-th CR among the composition rectangles belonging to the lIdx-th layer among the subpictures belonging to the lIdx-th layer. The number of bits to signal cr_subpic_idx[ lIdx ][ crIdx ] is cr_subpic_idx_len_minus1 + 1.

[0313] The above CR-related message may include index length information representing information related to the length of the above subpicture index information. The above index length information may correspond to the syntax element cr_subpic_idx_len_minus1 among the syntaxes of Table 4. cr_subpic_idx_len_minus1 + 1 may represent the length of cr_subpic_idx[ lIdx ][ crIdx ].

[0314] The above CR-related message may include subpicture index availability information indicating whether the index length information is included in the above CR-related message. The above subpicture index availability information may correspond to the syntax element cr_subpic_idx_enabled_flag among the syntaxes of Table 4. cr_subpic_idx_enabled_flag may indicate whether the syntax element cr_subpic_idx_len_minus1 exists in the CR SEI message. A cr_subpic_idx_enabled_flag equal to 1 indicates that the syntax element cr_subpic_idx_len_minus1 exists in the CR SEI message. Therefore, when cr_subpic_idx_enabled_flag is 1, the decoding device (200) can acquire or parse cr_subpic_idx_len_minus1. A cr_subpic_idx_enabled_flag equal to 0 indicates that the syntax element cr_subpic_idx_len_minus1 does not exist in the SEI message.

[0315] The above CR-related message may include CR partitioning information indicating whether the constituent rectangle is derived based on subpictures. The CR partitioning information may correspond to the syntax element cr_subpics_partitioning_flag[ lIdx ] among the syntaxes of Table 4. cr_subpics_partitioning_flag[ lIdx ] is information indicating whether the subpicture partitioning parameter included in the SPS associated with the lIdx-th layer is used to determine the size and position of the constituent rectangle. When cr_subpics_partitioning_flag[ lIdx ] is equal to 1, it indicates that the subpicture partitioning parameter included in the SPS associated with the lIdx-th layer is used to determine the size and position of the constituent rectangle. A cr_subpics_partitioning_flag equal to 0 indicates that the determination of the size and position of the constituent rectangle is not based on the subpicture partitioning parameters included in the SPS.

[0316] The above subpicture index information may be included in the CR-related message based on the fact that the value of the CR partitioning information is 1 and the value of the subpicture index availability information is 1. In other words, the decoding device (300) can obtain or parse cr_subpic_idx[ lIdx ][ crIdx ] when cr_subpics_partitioning_flag[ lIdx ] is true (e.g., when it is 1) and cr_subpic_idx_enabled_flag is true (e.g., when it is 1). That is, when cr_subpics_partitioning_flag[ lIdx ] is true (e.g., when it is 1) and the value of cr_subpic_idx_enabled_flag is 1 (e.g., when it is 1), the subpicture index information may be included in the CR-related message.

[0317] As mentioned above, by signaling / parsing the index information of the subpicture associated with the configuration rectangle, accurate coding becomes possible and coding efficiency can be improved.

[0318] FIG. 9 is a diagram showing another example of a method for encoding image information according to one embodiment.

[0319] The method according to the example can be performed by an encoding device (200) according to one embodiment. Accordingly, all or part of the description of the encoding device (200) described above and the description of the encoding method described with reference to FIG. 5 may also be applied to the method according to one embodiment. That is, the descriptions described above may also be applied to the method according to one embodiment to the extent that they do not conflict with the descriptions described below.

[0320] The encoding device (200) may include a memory and a processor electrically connected to the memory, and the operation of the aforementioned encoding device (200), the encoding method, or the method described below may be executed by the processor of the encoding device (200).

[0321] Terms or names used in this disclosure (e.g., names of syntax elements or names of variables, etc.) are merely examples, and the scope of the embodiments is not limited to these terms. Even if a term is not used in this disclosure, if substantial features such as the function performed, the definition thereof, or the method by which it is derived are identical or similar to those of this disclosure, it may be considered to be included within the scope of the embodiments described in this disclosure.

[0322] In addition, the method according to one embodiment may include other operations in addition to the operations described below, and some of the operations described below may be omitted depending on the example.

[0323] Meanwhile, depending on the modification of the embodiment, the syntax of Table 3 may be applied to the method of encoding or decoding image information according to one embodiment. In this case, the description of Table 3 described above may be applied.

[0324] Referring to FIG. 9, a method for encoding image information according to one embodiment may include the step of generating a CR-related message containing information related to the number of constituent rectangles belonging to a specific layer among at least one layer (S1210), and the step of encoding image information containing the CR-related message (S1220).

[0325] For example, a CR-related message generated according to the method of FIG. 9 may include some or all of the syntax of the aforementioned tables. Therefore, at least some of the contents described with reference to the tables above may also be applied to this example.

[0326] The number of subpictures belonging to the aforementioned specific layer is greater than or equal to the number of constituent rectangles belonging to the aforementioned specific layer. This may be a constraint on the bitstream. Therefore, when this example applies, the number of subpictures belonging to the specific layer must be greater than or equal to the number of constituent rectangles belonging to the aforementioned specific layer.

[0327] Specifically, when cr_subpics_partitioning_flag is equal to 1, NumSubpics can be greater than or equal to cr_num_rects_in_layer_minus1 [ lIdx ] + 1, thereby changing the constraints, that is, the requirements for bitstream consistency. That is, when a constituent rectangle is derived from a subpicture, or when a constituent rectangle is partitioned based on a subpicture, the number of subpictures must be greater than or equal to the number of constituent rectangles within a specific layer. In other words, when a subpicture partitioning parameter included in the SPS associated with the layer with index value lIdx is used to determine the size and position of the constituent rectangle, the number of subpictures must be greater than or equal to the number of constituent rectangles within the layer with index value lIdx. As a result, constraints related to the number of composition rectangles and subpictures become accurate, and errors during the coding process can be prevented.

[0328] A bitstream is generated based on video information encoded according to the encoding method described above, and the bitstream can be stored non-transiently on a computer-readable storage medium.

[0329] Additionally, a method for transmitting a bitstream according to one embodiment may include the step of generating a bitstream and the step of transmitting data including said bitstream. Here, the bitstream may be generated based on the aforementioned encoding method.

[0330] FIG. 10 is a diagram showing another example of a method for decoding image information according to one embodiment.

[0331] A method according to one embodiment may be performed by a decoding device (300) according to one embodiment. Accordingly, all or part of the description of the decoding device (300) described above and the description of the decoding method described with reference to FIG. 4 may also be applied to a method according to one embodiment. That is, the descriptions described above may also be applied to a method according to one embodiment to the extent that they do not conflict with the descriptions described below.

[0332] The decoding device (300) may include a memory and a processor electrically connected to the memory, and the operation of the decoding device (300) described above, the decoding method, or the method described below may be executed by the processor of the decoding device (300).

[0333] Terms or names used in this disclosure (e.g., names of syntax elements or names of variables, etc.) are merely examples, and the scope of the embodiments is not limited to these terms. Even if a term is not used in this disclosure, if substantial features such as the function performed, the definition thereof, or the method by which it is derived are identical or similar to those of this disclosure, it may be considered to be included within the scope of the embodiments described in this disclosure.

[0334] In addition, the method according to one embodiment may include other operations in addition to the operations described below, and some of the operations described below may be omitted depending on the example.

[0335] Referring to FIG. 10, a method for decoding image information according to one embodiment may include the step of obtaining image information including a CR-related message from a bitstream (S1310) and the step of deriving information related to the number of constituent rectangles belonging to a specific layer among at least one layer based on the CR-related message (S1320).

[0336] For example, a CR-related message obtained according to the method of FIG. 10 may include some or all of the syntax of the aforementioned tables. Therefore, at least some of the contents described with reference to the tables above may also be applied to this example.

[0337] The number of subpictures belonging to the aforementioned specific layer is greater than or equal to the number of constituent rectangles belonging to the aforementioned specific layer. This may be a constraint on the bitstream. Therefore, when this example applies, the number of subpictures belonging to the specific layer must be greater than or equal to the number of constituent rectangles belonging to the aforementioned specific layer.

[0338] Specifically, when cr_subpics_partitioning_flag is equal to 1, NumSubpics can be greater than or equal to cr_num_rects_in_layer_minus1 [ lIdx ] + 1, thereby changing the constraints, that is, the requirements for bitstream consistency. That is, when a constituent rectangle is derived from a subpicture, or when a constituent rectangle is partitioned based on a subpicture, the number of subpictures must be greater than or equal to the number of constituent rectangles within a specific layer. In other words, when a subpicture partitioning parameter included in the SPS associated with the layer with index value lIdx is used to determine the size and position of the constituent rectangle, the number of subpictures must be greater than or equal to the number of constituent rectangles within the layer with index value lIdx. As a result, constraints related to the number of composition rectangles and subpictures become accurate, and errors during the coding process can be prevented.

[0339] FIG. 11 is a drawing illustrating an exemplary content streaming system to which an embodiment according to the present disclosure can be applied.

[0340] As illustrated in FIG. 11, a content streaming system to which an embodiment of the present disclosure is applied may largely include an encoding server, a streaming server, a web server, a media storage, a user device, and a multimedia input device.

[0341] The above encoding server compresses content input from multimedia input devices, such as smartphones, cameras, and camcorders, into digital data to generate a bitstream and transmits it to the streaming server. As another example, if multimedia input devices, such as smartphones, cameras, and camcorders, generate the bitstream directly, the encoding server may be omitted.

[0342] The bitstream may be generated by a video encoding method and / or encoding device to which an embodiment of the present disclosure is applied, and the streaming server may temporarily store the bitstream during the process of transmitting or receiving the bitstream.

[0343] The streaming server transmits multimedia data to a user device based on a user request through a web server, and the web server can act as a medium to inform the user of available services. When a user requests a desired service from the web server, the web server transmits it to the streaming server, and the streaming server can transmit multimedia data to the user. At this time, the content streaming system may include a separate control server, and in this case, the control server can perform the role of controlling commands and responses between each device within the content streaming system.

[0344] The streaming server can receive content from a media storage and / or an encoding server. For example, when receiving content from the encoding server, the content can be received in real time. In this case, to provide a seamless streaming service, the streaming server can store the bitstream for a certain period of time.

[0345] Examples of the above user devices may include mobile phones, smartphones, laptop computers, digital broadcasting terminals, PDAs (personal digital assistants), PMPs (portable multimedia players), navigation systems, slate PCs, tablet PCs, ultrabooks, wearable devices (e.g., smartwatches, smart glasses, HMDs (head-mounted displays)), digital TVs, desktop computers, digital signage, etc.

[0346] Each server within the above-mentioned content streaming system can be operated as a distributed server, and in this case, data received from each server can be processed in a distributed manner.

[0347] The scope of the present disclosure includes software or machine-executable instructions (e.g., operating system, application, firmware, program, etc.) that enable an operation according to a method of various embodiments to be executed on a device or computer, and a non-transitory computer-readable medium on which such software or instructions, etc. are stored and executable on a device or computer.

[0348] An embodiment according to the present disclosure can be used to encode / decode images.

Claims

1. A step of obtaining image information including a CR (Constituent Rectangle) related message from a bitstream; and Based on the above CR-related message, the method includes the step of identifying a subpicture associated with each of the at least one constituent rectangles belonging to a specific layer among at least one layer. The above CR-related message is, A method comprising, for the specific layer above, subpicture index information representing a subpicture associated with each of the constituent rectangles.

2. In Paragraph 1, A method in which the subpicture associated with each of the above-mentioned constituent rectangles is a subpicture belonging to the above-mentioned specific layer.

3. In Paragraph 1, A method in which the above CR-related message includes index length information representing information related to the length of the above subpicture index information.

4. In Paragraph 3, A method in which the above CR-related message includes subpicture index availability information indicating whether the index length information is included in the above CR-related message.

5. In Paragraph 4, A method in which the above subpicture index information is included in the above CR-related message based on the value of the above subpicture index availability information being 1.

6. In Paragraph 4, A method in which the above CR-related message includes CR segmentation information indicating whether the above-mentioned configuration rectangle is derived based on the above-mentioned subpicture.

7. In Paragraph 6, A method in which the above subpicture index information is included in the above CR-related message based on the fact that the value of the above CR partition information is 1 and the value of the above subpicture index availability information is 1.

8. For a specific layer among at least one layer, a step of generating a CR-related message identifying a subpicture associated with each of at least one constituent rectangles among at least one constituent rectangle; and The method includes the step of encoding image information containing the above CR-related message; and The above CR-related message is, A method comprising, for the specific layer above, subpicture index information representing a subpicture associated with each of the constituent rectangles.

9. In Paragraph 8, A method in which the subpicture associated with each of the above-mentioned constituent rectangles is a subpicture belonging to the above-mentioned specific layer.

10. In Paragraph 8, A method in which the above CR-related message includes index length information representing information related to the length of the above subpicture index information.

11. In Paragraph 10, A method in which the above CR-related message includes subpicture index availability information indicating whether the index length information is included in the above CR-related message.

12. In Paragraph 11, A method in which the above subpicture index information is included in the above CR-related message based on the value of the above subpicture index availability information being 1.

13. In Paragraph 11, A method in which the above CR-related message includes CR segmentation information indicating whether the above-mentioned configuration rectangle is derived based on the above-mentioned subpicture.

14. In Paragraph 13, A method in which the above subpicture index information is included in the above CR-related message based on the fact that the value of the above CR partition information is 1 and the value of the above subpicture index availability information is 1.

15. A computer-readable storage medium that non-transiently stores a bitstream generated by the method of claim 8 above.

16. Step of generating a bitstream; and The method includes the step of transmitting data including the bitstream above; and The step of generating the above bitstream is, For a specific layer among at least one layer, a step of generating a CR-related message that identifies a subpicture associated with each of the at least one constituent rectangles among at least one constituent rectangle; and The method includes the step of encoding image information containing the above CR-related message; and The above CR-related message is, A method comprising, for the specific layer above, subpicture index information representing a subpicture associated with each of the constituent rectangles.

Images