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 packed regions information (PRI) SEI message; and acquiring, from the PRI SEI message, a first flag indicating whether parameter information about a target picture exists. The method may include a method for acquiring, on the basis of the value of the first flag, information indicating a relationship of chroma sampling to luma sampling of the target picture and information indicating the luma bit depth of the target picture, and acquiring information indicating the chroma bit depth of the target picture on the basis of an information value indicating the relationship of the chroma sampling to the luma sampling of the target picture.

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 with improved 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 may include: a step of obtaining image information including packed regions information (PRI) SEI messages from a bitstream; and a step of obtaining a first flag [Orange 1.1] indicating whether parameter information of a target picture exists from the packed regions information (PRI) SEI messages, and based on the value of the first flag, obtaining information indicating the relationship between chroma sampling and lumina sampling of the target picture and information indicating the lumina bit depth of the target picture, and based on the value of the information indicating the relationship between chroma sampling and lumina sampling of the target picture, obtaining information indicating the chroma bit depth of the target picture.

[0008] A method for obtaining information representing the chroma bit depth of the target picture may be included based on the fact that the information value representing the relationship between the luminance sampling and the chroma sampling of the target picture is not zero.

[0009] Based on the first flag value above, a method for obtaining information indicating the top-left position of rectangular regions within a target picture may be included.

[0010] Based on the first flag value above, a method for obtaining information indicating the width of the target picture and information indicating the height of the target picture may be included.

[0011] The method may further include the step of obtaining a second flag indicating whether the parameter information of the target picture is updated based on the first flag value.

[0012] Based on the fact that the first flag value is 1, a method for obtaining the second flag may be included.

[0013] Based on the values ​​of the first flag and the second flag, the method may include obtaining information indicating the relationship between chroma sampling and lumina sampling of the target picture and information indicating the lumina bit depth of the target picture.

[0014] Based on the fact that the values ​​of the first flag and the second flag are 1, the method may include information indicating the relationship between chroma sampling and lumina sampling of the target picture and information indicating the lumina bit depth of the target picture.

[0015] A method for obtaining information representing the chroma bit depth of the target picture may be included based on the fact that the information value representing the relationship between the luminance sampling and the chroma sampling of the target picture is not zero.

[0016] A method according to one aspect comprises: generating parameter information of a target picture and a first flag indicating whether parameter information of the target picture exists; generating a packed regions information (PRI) SEI message including parameter information of the target picture; and encoding image information including the packed regions information (PRI) SEI message; wherein, based on the first flag value, information indicating the relationship of chroma sampling to lumina sampling of the target picture and information indicating the lumina bit depth of the target picture are included in the parameter information of the target picture, and based on the information value indicating the relationship of chroma sampling to lumina sampling of the target picture, information indicating the chroma bit depth of the target picture is included in the parameter information of the target picture.

[0017] 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 packed regions information (PRI) SEI message including parameter-related information of a target picture; and a step of encoding image information including said packed regions information (PRI) SEI message; wherein a first flag indicating whether parameter information of a target picture exists is included in the parameter-related information of the target picture, and based on the value of said first flag, information indicating the relationship of chroma sampling to lumina sampling of the target picture and information indicating the lumina bit depth of the target picture are included in the parameter-related information of the target picture, and based on the value of said first flag indicating the relationship of chroma sampling to lumina sampling of the target picture, information indicating the chroma bit depth of the target picture is included in the parameter-related information of the target picture.

[0018] 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.

[0019] According to the present disclosure, an encoding / decoding method and / or apparatus with improved coding efficiency can be provided.

[0020] According to the present disclosure, an encoding / decoding method and / or device with improved data transmission efficiency can be provided.

[0021] 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 belongs from the description below.

[0022] FIG. 1 is a schematic diagram illustrating a video coding system to which an embodiment according to the present disclosure can be applied.

[0023] FIG. 2 is a schematic diagram showing an encoding device to which an embodiment according to the present disclosure can be applied.

[0024] FIG. 3 is a schematic diagram showing a decoding device to which an embodiment according to the present disclosure can be applied.

[0025] FIG. 4 shows an example of a video / image decoding method to which one embodiment can be applied.

[0026] FIG. 5 shows an example of a video / image encoding method to which an embodiment of the present disclosure can be applied.

[0027] Figure 6 illustrates an exemplary hierarchical structure for a coded video / image.

[0028] FIG. 7 is a diagram illustrating a method for decoding image information according to one embodiment.

[0029] FIG. 8 is a diagram illustrating a method for encoding image information according to one embodiment.

[0030] FIG. 9 is a diagram showing another example of a method for decoding image information according to one embodiment.

[0031] FIG. 10 is a diagram showing another example of a method for encoding image information according to one embodiment.

[0032] FIG. 11 is a drawing illustrating an exemplary content streaming system to which an embodiment according to the present disclosure can be applied.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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 HEVC (High Efficiency Video Coding) standard, 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).

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] 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."

[0046] 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."

[0047] 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."

[0048] 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".

[0049] FIG. 1 is a schematic diagram illustrating a video / image coding system to which an embodiment according to the present disclosure can be applied.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] 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.

[0054] 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.

[0055] 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.

[0056] The renderer can render the decoded video / image. The rendered video / image can be displayed through the display unit.

[0057] FIG. 2 is a schematic diagram illustrating an encoding device to which an embodiment according to the present disclosure can be applied.

[0058] 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 aforementioned 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 Decoded Picture Buffer (DPB) and may be configured by a digital storage medium. The hardware component may further include the memory (270) as an internal / external component.

[0059] 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.

[0060] 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.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] 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.

[0065] The prediction signal generated through the prediction unit (220) can be used to generate a restoration signal or to generate a residual signal.

[0066] 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.

[0067] 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.

[0068] 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 (240) may encode information required for video / image restoration (e.g., values ​​of syntax elements) together or separately with the 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.

[0069] 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).

[0070] 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).

[0071] Meanwhile, LMCS (luma mapping with chroma scaling) may be applied during the picture encoding and / or restoration process.

[0072] 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.

[0073] 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 (270). 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.

[0074] 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.

[0075] 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).

[0076] FIG. 3 is a schematic diagram illustrating a decoding device to which an embodiment according to the present disclosure can be applied.

[0077] 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 (322). 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.

[0078] 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 derive units / blocks based on block division information obtained from the bitstream. 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. One or more conversion units may be derived from the coding unit. And, the restored image signal decoded and output through the decoding device (300) can be played back through a playback device (not shown).

[0079] 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).

[0080] 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.

[0081] In the inverse conversion unit (322), the conversion coefficients can be inversely converted to obtain a residual signal (residual block, residual sample array).

[0082] The prediction unit performs a prediction for the current block and can generate a predicted block containing prediction samples for the current block. Based on information regarding the prediction output from the entropy decoding unit (310), the prediction unit can determine whether an intra prediction or an inter prediction is applied to the current block, and can determine specific intra prediction modes and inter prediction modes.

[0083] 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.

[0084] The intra prediction unit (331) 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 intra prediction unit (331) may determine the prediction mode applied to the current block by using the prediction mode applied to the surrounding blocks.

[0085] 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.

[0086] 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 the 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.

[0087] The addition unit (340) may be called a restoration unit or a restoration block generation unit. The generated restoration signal may be used for intra-predicting the next block to be processed within the current picture, and may also be used for inter-predicting the next picture after filtering as described below.

[0088] Meanwhile, LMCS (luma mapping with chroma scaling) may be applied during the picture decoding process.

[0089] 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.

[0090] 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).

[0091] 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.

[0092] FIG. 4 shows an example of a video / image decoding method to which one embodiment can be applied.

[0093] 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.

[0094] 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.

[0095] 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 the quantized transformation coefficients) (S430).

[0096] 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.

[0097] 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.

[0098] FIG. 5 shows an example of a video / image encoding method to which an embodiment of the present disclosure can be applied.

[0099] 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.

[0100] 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.

[0101] 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.

[0102] 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.

[0103] 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.

[0104] 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.

[0105] 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.

[0106] Figure 6 illustrates an exemplary hierarchical structure for a coded video / image.

[0107] 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.

[0108] 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.

[0109] 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.

[0110] 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).

[0111] 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.

[0112] As described above, the NAL unit type can be specified 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.

[0113] 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.

[0114] 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.

[0115] - APS (Adaptation Parameter Set) NAL unit: Type for the NAL unit containing the APS

[0116] - DPS(Decoding Parameter Set) NAL unit: Type for the NAL unit containing the DPS

[0117] - VPS (Video Parameter Set) NAL unit: Type for the NAL unit containing the VPS

[0118] - SPS (Sequence Parameter Set) NAL unit: Type for NAL unit containing SPS

[0119] - PPS(Picture Parameter Set) NAL unit: Type for the NAL unit containing the PPS

[0120] 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.

[0121] 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.

[0122] 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.

[0123] 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).

[0124] Hereinafter, SEI messages related to the present invention will be described.

[0125] In the existing Advanced Video Coding (AVC) and its extended layered architecture, the payload of an SEI message was constructed and interpreted based on the payload type.

[0126] An example of a syntax table for SEI messages is shown in Table 1 below.

[0127] [Table 1]

[0128]

[0129]

[0130]

[0131]

[0132] The semantics for an SEI message whose payload type is in the range of 0 to 23 or is identical to any of 45, 47, 137, 142, 144, 147, 148, 149, 150, 151, 154, 155, 156, 200, 201, 202, 205, 210, 211, 212, 218 can be extended as follows.

[0133] If the payloadType is 3, 8, 19, 20, or 22, the following applies.

[0134] - If the SEI message is not included in the scalable nesting SEI message, it can be applied to the layer representations of the current access unit where dependency_id is 0 and quality_id is 0.

[0135] At this time, the semantics of the above SEI message may be applied to a bitstream obtained by calling a bitstream extraction process with targets set to dIdTarget=0 and qIdTarget=0. Additionally, the syntax elements and derived variables referenced in the above semantics may correspond to the syntax elements and variables for a layer representation with dependency_id=0 and quality_id=0. All SEI messages referenced in the above semantics may be SEI messages applied to layer representations where dependency_id is 0 and quality_id is 0.

[0136] - If the SEI message is included in a scalable nesting SEI message, the SEI message can be applied to layer representations of the current access unit where the DQId (Dependency and Quality Identifier) ​​is equal to any one of the values ​​of ((sei_dependency_id[i] << 4) + sei_quality_id[i]) for i in the range of 0 to num_layer_representations_minus1.

[0137] At this time, for each value of i in the range of 0 or greater and num_layer_representations_minus1 or less, the semantics of the SEI message can be applied to the bitstream obtained by calling the bitstream extraction process with dIdTarget=sei_dependency_id[i] and qIdTarget=sei_quality_id[i]. Additionally, the syntax elements referenced in the semantics and the derived variables correspond to the syntax elements and variables for the layer representation where dependency_id is sei_dependency_id[i] and quality_id is sei_quality_id[i], and all of the SEI messages may be SEI messages applied to layer representations where dependency_id is sei_dependency_id[i] and quality_id is sei_quality_id[i].

[0138] In other cases, for SEI messages where the payloadType is the same as any one of 2, 6, 7, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 21, 23, 45, 47, 137, 142, 144, 147, 148, 149, 150, 151, 154, 155, 156, 200, 201, 202, 205, 210, 211, 212, or 218, the following applies.

[0139] - If the corresponding SEI message is not included within a scalable nesting SEI message, it is applied to dependency representations with dependency_id 0 among the dependency representations of the current access unit. In this case, the semantics of the SEI message may be applied to the bitstream obtained by calling the bitstream extraction process with dIdTarget=0. Additionally, the syntax elements and derived variables referenced in the semantics correspond to the syntax elements and variables for the dependency representation with dependency_id 0, and all SEI messages referenced in the semantics may be SEI messages applied to dependency representations with dependency_id 0.

[0140] - In other cases, that is, when the said SEI message is included within a scalable nesting SEI message, the scalable nesting SEI message containing said SEI message must have all_layer_representations_in_au_flag equal to 1, or if all_layer_representations_in_au_flag equal to 0, all sei_quality_id[i] values ​​existing within the scalable nesting SEI message must be equal to 0. Additionally, said SEI message included within the scalable nesting SEI message applies to all dependency representations of the current access unit that have a dependency_id equal to any one of the sei_dependency_id[i] values ​​when i is in the range from 0 to num_layer_representations_minus1. At this time, for each value of i in the range of 0 or greater and num_layer_representations_minus1 or less, the semantics of the SEI message can be applied to the bitstream obtained by calling the bitstream extraction process with dIdTarget=sei_dependency_id[i]. Additionally, the syntax elements referenced in the semantics and the derived variables correspond to the syntax elements and variables for the dependency expression where dependency_id is sei_dependency_id[i], and all SEI messages referenced in the semantics may be SEI messages applied to the dependency expressions where dependency_id is sei_dependency_id[i].

[0141] If the payloadType of the SEI message included within the scalable nesting SEI message is 10, the semantics for sub_seq_layer_num of the sub-sequence information SEI message may be changed as follows. sub_seq_layer_num represents the sub-sequence layer number of the current picture. If the current picture belongs to a subsequence where the first picture in the decoding order is an IDR (Instantaneous Decoder Refresh) picture, the value of sub_seq_layer_num must be equal to 0. Additionally, if it is a non-paired reference field, the value of sub_seq_layer_num must be 0. sub_seq_layer_num must be in the range of 0 to 255 (inclusive).

[0142] In other cases, for SEI messages where the payloadType is 0 or 1, the following applies.

[0143] - If the relevant SEI message is not included within a scalable nesting SEI message, the following applies. All other SEI messages that are not included within a scalable nesting SEI message and have a payloadType equal to 0 or 1 are used as buffering period SEI messages and picture timing SEI messages for bitstream conformance, and where a decoding process is used, said bitstream must conform to this recommendation / international standard. Additionally, the seq_parameter_set_id value in a buffering period SEI message that is not included within a scalable nesting SEI message must be the same as the seq_parameter_set_id value of the picture parameter set referenced by the layer representation with a DQId (Dependency and Quality Identifier) ​​of 0 in the primary coded picture within the same access unit.

[0144] - In other cases, i.e., when the SEI message is included within a scalable nesting SEI message, the following applies. When the said SEI message and all other SEI messages, which are included within a scalable nesting SEI message in which the values ​​of sei_temporal_id, sei_dependency_id[i], and sei_quality_id[i] are identical and whose payloadType is 0 or 1, are used as buffering period SEI messages and picture timing SEI messages for bitstream conformance, the bitstream obtained by calling the bitstream extraction process with tIdTarget=sei_temporal_id, dIdTarget=sei_dependency_id[i], and qIdTarget=sei_quality_id[i] must conform to this recommendation / international standard.Additionally, the syntax elements num_units_in_tick, time_scale, fixed_frame_rate_flag, nal_hrd_parameters_present_flag, vcl_hrd_parameters_present_flag, low_delay_hrd_flag, pic_struct_present_flag and derived variables NalHrdBpPresentFlag, VclHrdBpPresentFlag, CpbDpbDelaysPresentFlag is set to syntax elements vui_ext_num_units_in_tick[i], vui_ext_time_scale[i], vui_ext_fixed_frame_rate_flag[i], vui_ext_nal_hrd_parameters_present_flag[i], respectively. vui_ext_vcl_hrd_parameters_present_flag[i], vui_ext_low_delay_hrd_flag[i], vui_ext_pic_struct_present_flag[i] and the derived variables VuiExtNalHrdBpPresentFlag[i], VuiExtVclHrdBpPresentFlag[i], and VuiExtCpbDpbDelaysPresentFlag[i] can be replaced.

[0145] In addition, the seq_parameter_set_id value in the buffering period SEI message included in the scalable nesting SEI message having the values ​​of sei_dependency_id[i] and sei_quality_id[i] must be the same as the seq_parameter_set_id value in the picture parameter set referenced by the layer representation of the primary coded picture within the same access unit whose DQId (Dependency and Quality Identifier) ​​is ((sei_dependency_id[i] << 4) + sei_quality_id[i]).

[0146] If the payloadType is 4 or 5, the semantics corresponding to the SEI message are not expanded.

[0147] If a specific SEI message of payloadType 137 or 144 is included in a scalable nesting SEI message and is applied to a specific combination of dependency_id, quality_id, and temporal_id in any access unit, the SEI message of payloadType applied to the specific combination of dependency_id, quality_id, and temporal_id must exist within the scalable nesting SEI message in the IDR access unit, which is the first access unit of the coded video sequence.

[0148] All SEI messages included within scalable nesting SEI messages present in a coded video sequence, where a specific value of payloadType is 137 or 144 and applied to a specific combination of dependency_id, quality_id and temporal_id, must have the same content.

[0149] For the semantics of an SEI message where the payloadType is in the range of 0 to 23 or is any one of 45, 47, 137, 142, 144, 147, 148, 149, 150, 151, 154, 155, 156, 200, 201, 202, 205, 210, 211, 212, 218, the sequence parameter set is replaced with the SVC sequence parameter set, and the parameters of the currently applied picture parameter set RBSP and Scalable Video Coding (SVC) sequence parameter set RBSP may be used.

[0150] A coded video sequence suitable for one or more profiles must not include an SEI NAL unit containing an SEI message with a payload type in the range of 36 to 44 or equal to 46, or an SEI NAL unit containing an SEI message with a payload type in the range of 48 to 53.

[0151] If an SEI NAL unit contains an SEI message in which the payloadType ranges from 24 to 35, the SEI NAL unit must not contain any SEI message among the SEI messages not included in the scalable nesting SEI message that has a payloadType less than 24 or is 45, 47, 137, 142, 144, 147, 148, 149, 150, 151, 154, 155, 156, 200, 201, 202, 205, 210, 211, 212, or 218, and the payloadType of the first SEI message of the SEI NAL unit must be in the range from 24 to 35.

[0152] If an SEI NAL unit contains an SEI message with a payloadType of 24, 28, or 29, the SEI NAL unit must not contain an SEI message with a payloadType that is not 24, 28, or 29.

[0153] If a scalable nesting SEI message exists within an SEI NAL unit and the payload type is 30, the scalable nesting SEI message must be the only SEI message within the SEI NAL unit.

[0154] In the existing HEVC (High Efficiency Video Coding) structure, payload interpretation of SEI messages is distinguished according to the NAL unit type, and for each case, the corresponding SEI payload is constructed and interpreted based on the payload type and payload size. An example of a syntax table for an HEVC SEI message is shown in Table 2 below.

[0155] [Table 2]

[0156]

[0157]

[0158]

[0159]

[0160] A SingleLayerSeiList consists of payloadType values ​​of 2, 3, 6, 9, 15, 16, 17, 19, 22, 23, 45, 47, 56, 128, 129, 131, 132, 134 or more and 152 or less, 154 or more and 159 or less, 200 or more and 202 or less, 205, 210 or more and 212 or less, 216, 218, and 220 or more and 222 or less.

[0161] Additionally, the VCL Associated Sei List consists of payloadType values ​​of 2, 3, 6, 9, 15, 16, 17, 19, 22, 23, 45, 47, 56, 128, 131, 132, 134 to 152, 154 to 159, 200 to 202, 205, 210 to 212, 216, 218, and 220 to 222.

[0162] Additionally, the picture unit repetition limit SEI list (PicUnitRepConSeiList) consists of payloadType values ​​of 0, 1, 2, 6, 9, 15, 16, 17, 19, 22, 23, 45, 47, 56, 128, 129, 131, 132, 133, 135 or more and 152 or less, 154 or more and 159 or less, 200 or more and 202 or less, 205, 210 or more and 212 or less, 216, 218, and 220 or more and 222 or less.

[0163] Additionally, the SingleLayerSeiList is composed of payloadType values ​​of SEI messages, but 0 corresponding to a buffering period SEI message, 1 corresponding to a picture timing SEI message, 4 corresponding to a user data registered by Recommendation SEI message, 5 corresponding to a user data unregistered SEI message, 130 corresponding to a decoding unit information SEI message, and 133 corresponding to a scalable nesting SEI message may be excluded.

[0164] Additionally, the VCL Associated SeiList may consist of payloadType values ​​of SEI messages that allow constraints on the NAL unit header of the SEI NAL unit to be inferred based on the NAL unit header of the associated VCL NAL unit when the SEI NAL unit is included in a non-scalable-nested state. Additionally, the Picture Unit Rep Con SeiList may consist of payloadType values ​​of SEI messages to which the 8 repetitions per picture unit limit applies.

[0165] Hereinafter, SEI messages related to the present invention will be described.

[0166] A Packed regions information (PRI) SEI message (hereinafter referred to as the PRI SEI message) is a message that provides information regarding rectangular regions within a coded picture. In this disclosure, a rectangular region is a region corresponding to a specific area within a coded picture, and metadata regarding its location and size may be defined by the PRI SEI message. Specifically, each rectangular region may form a specific range through the top-left position in luma sample units within a cropped decoded picture, and width and height, which are the dimensions in the horizontal and vertical directions. A decoder can use the metadata to recover a target picture from a decoded picture containing packed regions.

[0167] The PRI SEI message may contain information regarding the number, location, and size of each region, and can be used to reconstruct the target picture using samples of the cropped decoded picture corresponding to those regions. An example of a syntax table for the PRI SEI message is shown in Table 3 below.

[0168] [Table 3]

[0169]

[0170] The use of this PRI SEI message requires the definition of the following variables:

[0171] - Picture width and picture height in luma samples, denoted as PicWidthInLumaSamples and PicHeightInLumaSamples, respectively

[0172] - Maximum picture width and maximum picture height in luma sample units, denoted as MaxPicWidth and MaxPicHeight, respectively

[0173] - Chroma format specifier denoted as ChromaFormatIdc

[0174] - 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.

[0175] If pri_cancel_flag is equal to 1, it indicates that this SEI message cancels the persistence of the previous PRI SEI message in the output order applied to the current layer. If pri_cancel_flag is equal to 0, it indicates that packed regions information is subsequently signaled.

[0176] pri_persistence_flag specifies the persistence of PRI SEI messages for the current layer.

[0177] If pri_persistence_flag is equal to 0, it specifies that packed regions information applies only to the current decoded picture. If pri_persistence_flag is equal to 1, it indicates that PRI SEI messages apply to the current decoded picture and may persist for subsequent pictures in the current layer's output order until one or more of the following conditions become true:

[0178] - When a new CLVS (Coded Layer Video Sequence) of the current layer starts.

[0179] - When the bitstream ends.

[0180] - When the current layer picture within the AU (access unit) associated with the PRI SEI message is output after the current picture in the output order.

[0181] pri_num_regions_minus1 + 1 represents the number of regions where information is signaled.

[0182] If pri_multilayer_flag is equal to 1, it indicates that the syntax element pri_region_layer_id[ i ] may exist in the PRI SEI message. If pri_multilayer_flag is equal to 0, it indicates that the syntax element pri_region_layer_id[ i ] may not exist in the PRI SEI message.

[0183] If pri_use_max_dimensions_flag is equal to 1, it indicates that MaxPicWidth, MaxPicHeight, PicWidthInLumaSamples, and PicHeightInLumaSamples can be used for variable calculations. If pri_use_max_dimensions_flag is equal to 0, it indicates that MaxPicWidth, MaxPicHeight, PicWidthInLumaSamples, and PicHeightInLumaSamples may not be used for variable calculations for region parameters.

[0184] pri_log2_unit_size represents the unit size used for variable calculations for area parameters.

[0185] The variable priUnitSize is set to 1 << pri_log2_unit_size.

[0186] pri_region_size_len_minus1 + 1 represents the number of bits used to signal pri_region_top_left_in_units_x[ i ], pri_region_top_left_in_units_y[ i ], pri_region_width_in_units_minus1[ i ], pri_region_height_in_units_minus1[ i ], pri_target_region_top_left_x[ i ], and pri_target_region_top_left_y[ i ].

[0187] If pri_region_id_present_flag is equal to 1, it indicates that the syntax element pri_region_id[ i ] may exist in the PRI SEI message. If pri_region_id_present_flag is equal to 0, it indicates that the syntax element pri_region_id[ i ] may not exist in the PRI SEI message.

[0188] If pri_target_pic_params_present_flag is equal to 1, it indicates that the syntax elements pri_target_region_top_left_x[ i ], pri_target_region_top_left_y[ i ], pri_target_pic_width_minus1, and pri_target_pic_height_minus1 may be present in the PRI SEI message. If pri_target_pic_params_present_flag is equal to 0, it indicates that the syntax elements pri_target_region_top_left_x[ i ], pri_target_region_top_left_y[ i ], pri_target_pic_width_minus1, and pri_target_pic_height_minus1 may not be present in the PRI SEI message.

[0189] If pri_target_pic_width_minus1 + 1 and pri_target_pic_height_minus1 + 1 are present in the PRI SEI message, the width and height of the target picture that can be restored from samples of the cropped decoded picture corresponding to the regions described by this SEI message are indicated in units of luma samples.

[0190] pri_num_resampling_ratios_minus1 + 1 represents the number of resampling ratios being signaled.

[0191] pri_resampling_width_num_minus1[ i ] + 1 and pri_resampling_width_denom_minus1[ i ] + 1 represent the numerator and denominator, respectively, for width resampling of the i-th resampling ratio. pri_resampling_width_num_minus1[ i ] and pri_resampling_width_denom_minus1[ i ] may be values ​​within the range (inclusive) of 0 to 65535.

[0192] If the above syntax elements are not present in the PRI SEI message, the values ​​of pri_resampling_ratio_width_num_minus1

[0000] and pri_resampling_ratio_width_denom_minus1

[0000] are inferred to be equal to 0.

[0193] If pri_fixed_aspect_ratio_flag[ i ] is equal to 1, it indicates that the syntax elements pri_resampling_height_num_minus1[ i ] and pri_resampling_height_denom_minus1[ i ] may not exist in the PRI SEI message. If pri_fixed_aspect_ratio_flag[ i ] is equal to 0, it indicates that the syntax elements pri_resampling_height_num_minus1[ i ] and pri_resampling_height_denom_minus1[ i ] may exist in the PRI SEI message.

[0194] pri_resampling_height_num_minus1[ i ] + 1 and pri_resampling_height_denom_minus1[ i ] + 1 specify the numerator and denominator, respectively, for the height resampling of the i-th resampling ratio. The values ​​of pri_resampling_height_num_minus1[ i ] and pri_resampling_height_denom_minus1[ i ] may be values ​​within the range (inclusive) of 0 to 65 535.

[0195] If the above syntax elements do not exist in the PRI SEI message, the values ​​of pri_resampling_height_num_minus1[ i ] and pri_resampling_height_denom_minus1[ i ] are inferred to be the same as pri_resampling_width_num_minus1[ i ] and pri_resampling_width_denom_minus1[ i ], respectively.

[0196] pri_region_id[ i ] represents the ID of the i-th region. If pri_region_id[ i ] does not exist in the PRI SEI message, the value of pri_region_id[ i ] is inferred to be the same as i.

[0197] pri_region_layer_id[ i ] represents a layer ID indicating which layer pri_region_top_left_in_units_x[ i ], pri_region_top_left_in_units_y[ i ], pri_region_width_in_units_minus1[ i ] and pri_region_height_in_units_minus1[ i ] relate to.

[0198] If pri_region_is_a_layer_flag[ i ] is equal to 1, it indicates that the picture width and picture height in the layer with ID pri_region_layer_id[ i ] are equal to the area width and area height of index i, and that pri_region_top_left_in_units_x[ i ], pri_region_top_left_in_units_y[ i ], pri_region_width_in_units_minus1[ i ] and pri_region_height_in_units_minus1[ i ] may not be signaled. If pri_region_is_a_layer_flag[ i ] does not exist, the value of pri_region_is_a_layer_flag[ i ] is inferred to be equal to 0.

[0199] pri_region_top_left_in_units_x[ i ] and pri_region_top_left_in_units_y[ i ] represent the horizontal and vertical positions, respectively, based on the unit of the top-left sample of the i-th region.

[0200] The length of the above syntax elements is pri_region_size_len_minus1 + 1.

[0201] Within a cropped decoded picture with layer identifier pri_region_layer_id[ i ], the variables priRegionTopLeftX[ i ] and priRegionTopLeftY[ i ], representing the horizontal and vertical positions in luma samples of the i-th region respectively, are derived as follows:

[0202] [Formula 1]

[0203] if(!pri_use_max_dimensions_flag) {

[0204] priRegionTopLeftX[ i ] = pri_region_top_left_in_units_x[ i ] * priUnitSize

[0205] priRegionTopLeftY[ i ] = pri_region_top_left_in_units_y[ i ] * priUnitSize

[0206] } else {

[0207] priRegionTopLeftX[ i ] = ( pri_region_top_left_in_units_x[ i ] * priUnitSize * PicWidthInLumaSamples + MaxPicWidth / 2 ) / MaxWidth

[0208] priRegionTopLeftY[ i ] = ( pri_region_top_left_in_units_y[ i ] * priUnitSize* PicHeightInLumaSamples + MaxPicHeight / 2 ) / MaxHeight

[0209] }

[0210] pri_region_width_in_units_minus1[ i ] + 1 and pri_region_height_in_units_minus1[ i ] + 1 represent the width and height of the i-th region, respectively, based on units. The length of the above syntax elements is pri_region_size_len_minus1 + 1.

[0211] The variables priRegionWidth[ i ] and priRegionHeight[ i ], representing the width and height in luma samples of the i-th region within the cropped decoded picture, respectively, are derived as follows:

[0212] [Equation 2]

[0213] if(!pri_use_max_dimensions_flag) {

[0214] priRegionWidth[ i ] = ( pri_region_width_in_units_minus1 [ i ] + 1) * priUnitSize

[0215] priRegionHeight[ i ] = ( pri_region_height_in_units_minus1 [ i ] + 1) * priUnitSize

[0216] } else {

[0217] priRegionWidth[ i ] = ( ( pri_region_width_in_units_minus1 [ i ] + 1) * priUnitSize * PicWidthInLumaSamples + MaxPicWidth / 2 ) / MaxPicWidth

[0218] priRegionHeight[ i ] = ( ( pri_region_height_in_units_minus1 [ i ] + 1) * priUnitSize * PicHeightInLumaSamples + MaxPicHeight / 2 ) / MaxPicHeight

[0219] }

[0220] The variables SubWidthC and SubHeightC are derived from ChromaFormatIdc.

[0221] The requirement for bitstream conformity is that priRegionWidth[ i ] % SubWidthC is equal to 0 and priRegionHeight[ i ] % SubHeightC is equal to 0.

[0222] pri_resampling_ratio_idx[ i ] represents the index of the resampling ratio used for the i-th region. The length of the above syntax element is Ceil(Log2(pri_num_resampling_ratios_minus1 + 1)).

[0223] The variables priResampleWidthNum[ i ], priResampleWidthDenom[ i ], priResampleHeightNum[ i ], and priResampleHeightDenom[ i ] are derived as follows:

[0224] priResampleWidthNum[ i ] = pri_resampling_width_num_minus1[ pri_resampling_ratio_idx[ i ] ] + 1

[0225] priResampleWidthDenom[ i ] = pri_resampling_width_denom_minus1[ pri_resampling_ratio_idx[ i ] ] + 1

[0226] priResampleHeightNum[ i ] = pri_resampling_height_num_minus1[ pri_resampling_ratio_idx[ i ] ] + 1

[0227] priResampleHeightDenom[ i ] = pri_resampling_height_denom_minus1[ pri_resampling_ratio_idx[ i ] ] + 1

[0228] If pri_target_region_top_left_x[ i ] and pri_target_region_top_left_y[ i ] exist in the PRI SEI message, the horizontal and vertical positions of the top left sample position of the i-th region within the reconstructed target picture are indicated in units of luminous samples, respectively.

[0229] The variables priTargetRegionWidth and priTargetRegionHeight, representing the width and height of the resampled region within the reconstructed target picture in luma samples, respectively, are derived as follows:

[0230] priTargetRegionWidth = Round( ( priRegionWidth[ i ] * priResampleWidthNum[ i ] ) / ( priResampleWidthDenom[ i ] * SubWidthC ) ) * SubWidthC

[0231] priTargetRegionHeight = Round( ( priRegionHeight[ i ] * priResampleHeightNum[ i ] ) / ( priResampleHeightDenom[ i ] * SubHeightC ) ) * SubHeightC

[0232] When restoring a target picture with a lumina sample array of size (pri_target_pic_width_minus1 + 1) * (pri_target_pic_height_minus1 + 1), all lumina sample values ​​are initialized to 1 << (BitDepthY - 1), and if chroma samples exist, the chroma sample values ​​can be initialized to 1 << (BitDepthC - 1).

[0233] For sample position (x, y) and regions j and k, if all of the following conditions are satisfied, the reconstructed target picture sample at position (x, y) is determined by the parameters signaled for the j-th region.

[0234] -pri_region_id[j] > pri_region_id[k]

[0235] -x is in (priRegionTopLeftX[ j ] .. priRegionTopLeftX[ j ] + priRegionWidth[ j ])

[0236] -y is in (priRegionTopLeftY[ j ] .. priRegionTopLeftY[ j ] + priRegionHeight[ j ])

[0237] -x is in (priRegionTopLeftX[ k ] .. priRegionTopLeftX[ k ] + priRegionWidth[ k])

[0238] -y is in (priRegionTopLeftY[ k ] .. priRegionTopLeftY[ k ] + priRegionHeight[ k ])

[0239] Currently, to use a PRI SEI message, the decoder must be allocated some variables based on the codec of the bitstream containing the SEI message. To use a PRI SEI message, the decoder needs to allocate some variables based on the codec of the bitstream containing the SEI message. The information that must be provided by the codec to use a PRI SEI message is as follows.

[0240] To use the above SEI message, the following variables must be defined.

[0241] - As the picture width and picture height in Luma sample units, they are represented as PicWidthInLumaSamples and PicHeightInLumaSamples, respectively.

[0242] - As the maximum picture width and maximum picture height in Luma sample units, they are represented as MaxPicWidth and MaxPicHeight, respectively.

[0243] - The chroma format indicator is denoted as ChromaFormatIdc, the bit depth for the chroma component sample is denoted as BitDepthY, and if ChromaFormatIdc is not 0, the bit depth for the two associated chroma component samples is denoted as BitDepthC.

[0244] In VVC, the assignment of the above-mentioned necessary variables is performed as follows.

[0245] To interpret the PRI SEI message, the above variables are set as follows.

[0246] -PicWidthInLumaSamples is set to the same value as pps_pic_width_in_luma_samples - SubWidthC * ( pps_conf_win_left_offset + pps_conf_win_right_offset )

[0247] -PicHeightInLumaSamples is set to the same value as pps_pic_height_in_luma_samples - SubHeightC * ( pps_conf_win_top_offset + pps_conf_win_bottom_offset )

[0248] -MaxPicWidth is set to the same value as sps_pic_width_in_luma_samples - SubWidthC * ( sps_conf_win_left_offset + sps_conf_win_right_offset )

[0249] -MaxPicHeight is set to the same value as sps_pic_height_in_luma_samples - SubHeightC * ( sps_conf_win_top_offset + sps_conf_win_bottom_offset )

[0250] -ChromaFormatIdc is set to be the same as sps_chroma_format_idc.

[0251] -BitDepthY and BitDepthC are both set to be the same as BitDepth.

[0252] The current design regarding the chroma format indicator and bit depth mentioned above has the following problems.

[0253] The variables related to the chroma format indicator and bit depth mentioned above are required only when restoration of the target picture is necessary. In other words, since the target picture itself may or may not exist, the above variables are not always required.

[0254] In addition, in the current design, variables related to chroma format indicators and bit depth are provided by the codec interface. However, this is an inappropriate design because the selection of chroma format indicators and bit depth for the target picture must be determined by the decoder rather than relying on the codec using SEI messages.

[0255] Even if it is desirable for the above two variables to be provided by the codec, problems may arise when the bitstream contains multiple layers. When the bitstream contains multiple layers, there is a problem in that it is unclear which layer the values ​​for the chroma format indicator and bit depth should be used for.

[0256] 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:

[0257] According to one embodiment, the chroma format indicator and bit depth for the target picture of the packed regions may be explicitly signaled instead of being provided from the codec interface.

[0258] According to another embodiment, signaling regarding the chroma format indicator and bit depth may be specified only when target picture parameters exist.

[0259] Each embodiment or example is described in detail below.

[0260] According to one embodiment, if target picture parameters are present in the PRI SEI message, variables regarding chroma format indicators and bit depth may be signaled. To explicitly signal variables regarding chroma format indicators and bit depth in the PRI SEI, the syntax may be modified as shown in Table 4 below.

[0261] [Table 4]

[0262]

[0263] The PRI SEI message provides information about rectangular regions packed with the coded picture. This information can optionally be used to restore the target picture from samples of cropped decoded pictures corresponding to the rectangular regions described in this SEI message.

[0264] The use of this PRI SEI message requires the definition of the following variables:

[0265] - Picture width and picture height in luma samples, denoted as PicWidthInLumaSamples and PicHeightInLumaSamples, respectively

[0266] - Maximum picture width and maximum picture height in luma sample units, denoted as MaxPicWidth and MaxPicHeight, respectively

[0267] If pri_cancel_flag is equal to 1, it indicates that this SEI message cancels the persistence of the previous PRI SEI message in the output order applied to the current layer. If pri_cancel_flag is equal to 0, it indicates that packed regions information is subsequently signaled.

[0268] pri_persistence_flag specifies the persistence of PRI SEI messages for the current layer.

[0269] If pri_persistence_flag is equal to 0, it specifies that packed regions information applies only to the current decoded picture. If pri_persistence_flag is equal to 1, it indicates that PRI SEI messages apply to the current decoded picture and may persist for subsequent pictures in the current layer's output order until one or more of the following conditions become true:

[0270] - When a new CLVS (Coded Layer Video Sequence) of the current layer starts.

[0271] - When the bitstream ends.

[0272] - When the current layer picture within the AU (access unit) associated with the PRI SEI message is output after the current picture in the output order.

[0273] pri_num_regions_minus1 + 1 represents the number of regions where information is signaled.

[0274] If pri_multilayer_flag is equal to 1, it indicates that the syntax element pri_region_layer_id[ i ] may exist in the PRI SEI message. If pri_multilayer_flag is equal to 0, it indicates that the syntax element pri_region_layer_id[ i ] may not exist in the PRI SEI message.

[0275] If pri_use_max_dimensions_flag is equal to 1, it indicates that MaxPicWidth, MaxPicHeight, PicWidthInLumaSamples, and PicHeightInLumaSamples can be used for variable calculations. If pri_use_max_dimensions_flag is equal to 0, it indicates that MaxPicWidth, MaxPicHeight, PicWidthInLumaSamples, and PicHeightInLumaSamples may not be used for variable calculations for region parameters.

[0276] pri_log2_unit_size represents the unit size used for variable calculations for area parameters.

[0277] The variable priUnitSize is set to 1 << pri_log2_unit_size.

[0278] pri_region_size_len_minus1 + 1 represents the number of bits used to signal pri_region_top_left_in_units_x[ i ], pri_region_top_left_in_units_y[ i ], pri_region_width_in_units_minus1[ i ], pri_region_height_in_units_minus1[ i ], pri_target_region_top_left_x[ i ], and pri_target_region_top_left_y[ i ].

[0279] If pri_region_id_present_flag is equal to 1, it indicates that the syntax element pri_region_id[ i ] may exist in the PRI SEI message. If pri_region_id_present_flag is equal to 0, it indicates that the syntax element pri_region_id[ i ] may not exist in the PRI SEI message.

[0280] If pri_target_pic_params_present_flag is equal to 1, it indicates that the syntax elements pri_target_region_top_left_x[ i ], pri_target_region_top_left_y[ i ], pri_target_pic_width_minus1, and pri_target_pic_height_minus1 may be present in the PRI SEI message. If pri_target_pic_params_present_flag is equal to 0, it indicates that the syntax elements pri_target_region_top_left_x[ i ], pri_target_region_top_left_y[ i ], pri_target_pic_width_minus1, and pri_target_pic_height_minus1 may not be present in the PRI SEI message.

[0281] If pri_target_pic_width_minus1 + 1 and pri_target_pic_height_minus1 + 1 are present in the PRI SEI message, the width and height of the target picture that can be restored from samples of the cropped decoded picture corresponding to the regions described by this SEI message are indicated in units of luma samples.

[0282] Referring to Table 4 above, it can be seen that variables regarding chroma format indicators and bit depth can be directly signaled in the PRI SEI message. Specifically, if target picture parameters exist, the variables regarding chroma format indicators and bit depth can be signaled.

[0283] The pri_target_pic_params_present_flag in Table 4 above may indicate whether syntax elements such as pri_target_region_top_left_x[ i ], pri_target_region_top_left_y[ i ], pri_target_pic_width_minus1 and pri_target_pic_height_minus1 exist in the PRI SEI message.

[0284] pri_target_pic_params_present_flag with a value equal to 1 may indicate that syntax elements such as pri_target_region_top_left_x[ i ], pri_target_region_top_left_y[ i ], pri_target_pic_width_minus1 and pri_target_pic_height_minus1 exist in the PRI SEI message, and pri_target_pic_params_present_flag with a value equal to 0 may indicate that syntax elements such as pri_target_region_top_left_x[ i ], pri_target_region_top_left_y[ i ], pri_target_pic_width_minus1 and pri_target_pic_height_minus1 do not exist in the PRI SEI message.

[0285] If the value of the above pri_target_pic_params_present_flag is equal to 1, pri_target_pic_chroma_format_idc, which indicates the chroma format indicator of the target picture, and pri_target_bitdepthy_minus8, which is a variable regarding the luminance bit depth, can be signaled.

[0286] In addition, if the value of pri_target_pic_chroma_format_idc, which indicates the chroma format indicator of the target picture, is not 0, pri_target_bitdepthc_minus8, a variable regarding the chroma bit depth, can be signaled.

[0287] The above pri_target_pic_chroma_format_idc represents chroma sampling relative to lumina sampling for a target display picture.

[0288] The value obtained by adding 8 to the above pri_target_bitdepthy_minus8 may represent the luma bit depth of the target picture. In this case, pri_target_bitdepthy_minus8 may be in the range of 0 to 8, and the variable targetBitDepthY representing the luma bit depth of the target picture may be set to be equal to pri_target_bitdepthy_minus8 + 8.

[0289] The value obtained by adding 8 to the above pri_target_bitdepthc_minus8 may represent the chroma bit depth of the target picture. In this case, pri_target_bitdepthc_minus8 may be in the range of 0 to 8, and the variable targetBitDepthC, which represents the chroma bit depth of the target picture, may be set to be equal to pri_target_bitdepthc_minus8 + 8.

[0290] pri_resampling_width_num_minus1[ i ] + 1 and pri_resampling_width_denom_minus1[ i ] + 1 represent the numerator and denominator, respectively, for width resampling of the i-th resampling ratio. pri_resampling_width_num_minus1[ i ] and pri_resampling_width_denom_minus1[ i ] may be values ​​within the range (inclusive) of 0 to 65535.

[0291] If the above syntax elements are not present in the PRI SEI message, the values ​​of pri_resampling_ratio_width_num_minus1

[0000] and pri_resampling_ratio_width_denom_minus1

[0000] are inferred to be equal to 0.

[0292] If pri_fixed_aspect_ratio_flag[ i ] is equal to 1, it indicates that the syntax elements pri_resampling_height_num_minus1[ i ] and pri_resampling_height_denom_minus1[ i ] may not exist in the PRI SEI message. If pri_fixed_aspect_ratio_flag[ i ] is equal to 0, it indicates that the syntax elements pri_resampling_height_num_minus1[ i ] and pri_resampling_height_denom_minus1[ i ] may exist in the PRI SEI message.

[0293] pri_resampling_height_num_minus1[ i ] + 1 and pri_resampling_height_denom_minus1[ i ] + 1 specify the numerator and denominator, respectively, for the height resampling of the i-th resampling ratio. The values ​​of pri_resampling_height_num_minus1[ i ] and pri_resampling_height_denom_minus1[ i ] may be values ​​within the range (inclusive) of 0 to 65 535.

[0294] If the above syntax elements do not exist in the PRI SEI message, the values ​​of pri_resampling_height_num_minus1[ i ] and pri_resampling_height_denom_minus1[ i ] are inferred to be the same as pri_resampling_width_num_minus1[ i ] and pri_resampling_width_denom_minus1[ i ], respectively.

[0295] pri_region_id[ i ] represents the ID of the i-th region. If pri_region_id[ i ] does not exist in the PRI SEI message, the value of pri_region_id[ i ] is inferred to be the same as i.

[0296] pri_region_layer_id[ i ] represents a layer ID indicating which layer pri_region_top_left_in_units_x[ i ], pri_region_top_left_in_units_y[ i ], pri_region_width_in_units_minus1[ i ] and pri_region_height_in_units_minus1[ i ] relate to.

[0297] If pri_region_is_a_layer_flag[ i ] is equal to 1, it indicates that the picture width and picture height in the layer with ID pri_region_layer_id[ i ] are equal to the area width and area height of index i, and that pri_region_top_left_in_units_x[ i ], pri_region_top_left_in_units_y[ i ], pri_region_width_in_units_minus1[ i ] and pri_region_height_in_units_minus1[ i ] may not be signaled. If pri_region_is_a_layer_flag[ i ] does not exist, the value of pri_region_is_a_layer_flag[ i ] is inferred to be equal to 0.

[0298] pri_region_top_left_in_units_x[ i ] and pri_region_top_left_in_units_y[ i ] represent the horizontal and vertical positions, respectively, based on the unit of the top-left sample of the i-th region.

[0299] The length of the above syntax elements is pri_region_size_len_minus1 + 1.

[0300] Within a cropped decoded picture with layer identifier pri_region_layer_id[ i ], the variables priRegionTopLeftX[ i ] and priRegionTopLeftY[ i ], representing the horizontal and vertical positions in luma samples of the i-th region respectively, are derived as follows:

[0301] [Equation 3]

[0302] if(!pri_use_max_dimensions_flag) {

[0303] priRegionTopLeftX[ i ] = pri_region_top_left_in_units_x[ i ] * priUnitSize

[0304] priRegionTopLeftY[ i ] = pri_region_top_left_in_units_y[ i ] * priUnitSize

[0305] } else {

[0306] priRegionTopLeftX[ i ] = ( pri_region_top_left_in_units_x[ i ] * priUnitSize * PicWidthInLumaSamples + MaxPicWidth / 2 ) / MaxWidth

[0307] priRegionTopLeftY[ i ] = ( pri_region_top_left_in_units_y[ i ] * priUnitSize* PicHeightInLumaSamples + MaxPicHeight / 2 ) / MaxHeight

[0308] }

[0309] pri_region_width_in_units_minus1[ i ] + 1 and pri_region_height_in_units_minus1[ i ] + 1 represent the width and height of the i-th region, respectively, based on units. The length of the above syntax elements is pri_region_size_len_minus1 + 1.

[0310] Meanwhile, the variables priRegionWidth[ i ] and priRegionHeight[ i ], representing the width and height in luma samples of the i-th region within the cropped decoded picture, respectively, are derived as follows:

[0311] [Equation 4]

[0312] if(!pri_use_max_dimensions_flag) {

[0313] priRegionWidth[ i ] = ( pri_region_width_in_units_minus1 [ i ] + 1) * priUnitSize

[0314] priRegionHeight[ i ] = ( pri_region_height_in_units_minus1 [ i ] + 1) * priUnitSize

[0315] } else {

[0316] priRegionWidth[ i ] = ( ( pri_region_width_in_units_minus1 [ i ] + 1) * priUnitSize * PicWidthInLumaSamples + MaxPicWidth / 2 ) / MaxWidth

[0317] priRegionHeight[ i ] = ( ( pri_region_height_in_units_minus1 [ i ] + 1) * priUnitSize * PicHeightInLumaSamples + MaxPicHeight / 2 ) / MaxHeight

[0318] }

[0319] The above SubWidthC and SubHeightC variables can be derived from pri_target_pic_chroma_format_idc of the present embodiment. That is, the above SubWidthC and SubHeightC variables can be derived from pri_target_pic_chroma_format_idc explicitly signaled in the PRI SEI message.

[0320] The requirement for bitstream conformity is that priRegionWidth[ i ] % SubWidthC is equal to 0 and priRegionHeight[ i ] % SubHeightC is equal to 0.

[0321] pri_resampling_ratio_idx[ i ] represents the index of the resampling ratio used for the i-th region. The length of the above syntax element is Ceil(Log2(pri_num_resampling_ratios_minus1 + 1)).

[0322] The variables priResampleWidthNum[ i ], priResampleWidthDenom[ i ], priResampleHeightNum[ i ], and priResampleHeightDenom[ i ] are derived as follows:

[0323] priResampleWidthNum[ i ] = pri_resampling_width_num_minus1[ pri_resampling_ratio_idx[ i ] ] + 1

[0324] priResampleWidthDenom[ i ] = pri_resampling_width_denom_minus1[ pri_resampling_ratio_idx[ i ] ] + 1

[0325] priResampleHeightNum[ i ] = pri_resampling_height_num_minus1[ pri_resampling_ratio_idx[ i ] ] + 1

[0326] priResampleHeightDenom[ i ] = pri_resampling_height_denom_minus1[ pri_resampling_ratio_idx[ i ] ] + 1

[0327] If pri_target_region_top_left_x[ i ] and pri_target_region_top_left_y[ i ] exist in the PRI SEI message, the horizontal and vertical positions of the top left sample position of the i-th region within the reconstructed target picture are indicated in units of luminous samples, respectively.

[0328] The variables priTargetRegionWidth and priTargetRegionHeight, representing the width and height of the resampled region within the reconstructed target picture in luma samples, respectively, are derived as follows:

[0329] priTargetRegionWidth = Round( ( priRegionWidth[ i ] * priResampleWidthNum[ i ] ) / ( priResampleWidthDenom[ i ] * SubWidthC ) ) * SubWidthC

[0330] priTargetRegionHeight = Round( ( priRegionHeight[ i ] * priResampleHeightNum[ i ] ) / ( priResampleHeightDenom[ i ] * SubHeightC ) ) * SubHeightC

[0331] When restoring a target picture with a luminar sample array size of ( pri_target_pic_width_minus1 + 1 ) × ( pri_target_pic_height_minus1 + 1 ) all luminar sample values ​​can be initialized to 1 << ( targetBitDepthY - 1 ) and if chroma samples exist, those chroma samples can be initialized to 1 << ( targetBitDepthC - 1 ) . That is, the values ​​of the luminar samples and chroma samples used when restoring the target picture can be initialized based on targetBitDepthY and targetBitDepthC of the present embodiment.

[0332] For sample position (x, y) and regions j and k, if all of the following conditions are satisfied, the reconstructed target picture sample at position (x, y) is determined by the parameters signaled for the j-th region.

[0333] -pri_region_id[j] > pri_region_id[k]

[0334] -x is in (priRegionTopLeftX[ j ] .. priRegionTopLeftX[ j ] + priRegionWidth[ j ])

[0335] -y is in (priRegionTopLeftY[ j ] .. priRegionTopLeftY[ j ] + priRegionHeight[ j ])

[0336] -x is in (priRegionTopLeftX[ k ] .. priRegionTopLeftX[ k ] + priRegionWidth[ k])

[0337] -y is in (priRegionTopLeftY[ k ] .. priRegionTopLeftY[ k ] + priRegionHeight[ k ])

[0338] The following variables are defined to interpret the PRI SEI message:

[0339] -PicWidthInLumaSamples can be set to the same value as pps_pic_width_in_luma_samples - SubWidthC * ( pps_conf_win_left_offset + pps_conf_win_right_offset )

[0340] -PicHeightInLumaSamples can be set to the same value as pps_pic_height_in_luma_samples - SubHeightC * ( pps_conf_win_top_offset + pps_conf_win_bottom_offset )

[0341] -MaxPicWidth can be set to the value of sps_pic_width_in_luma_samples - SubWidthC * ( sps_conf_win_left_offset + sps_conf_win_right_offset )

[0342] -MaxPicHeight can be set to the value of sps_pic_height_in_luma_samples - SubHeightC * ( sps_conf_win_top_offset + sps_conf_win_bottom_offset )

[0343] According to one embodiment, when a target picture parameter exists and the target picture parameter is updated, variables regarding the chroma format indicator and bit depth may be signaled. To explicitly signal variables regarding the chroma format indicator and bit depth in PRI SEI, the syntax may be changed as shown in Table 5 below.

[0344] [Table 5]

[0345]

[0346] The use of this PRI SEI message requires the definition of the following variables:

[0347] - Picture width and picture height in luma samples, denoted as PicWidthInLumaSamples and PicHeightInLumaSamples, respectively

[0348] - Maximum picture width and maximum picture height in luma sample units, denoted as MaxPicWidth and MaxPicHeight, respectively

[0349] If pri_cancel_flag is equal to 1, it indicates that this SEI message cancels the persistence of the previous PRI SEI message in the output order applied to the current layer. If pri_cancel_flag is equal to 0, it indicates that packed regions information is subsequently signaled.

[0350] pri_persistence_flag specifies the persistence of PRI SEI messages for the current layer.

[0351] If pri_persistence_flag is equal to 0, it specifies that packed regions information applies only to the current decoded picture. If pri_persistence_flag is equal to 1, it indicates that PRI SEI messages apply to the current decoded picture and may persist for subsequent pictures in the current layer's output order until one or more of the following conditions become true:

[0352] - When a new CLVS (Coded Layer Video Sequence) of the current layer starts.

[0353] - When the bitstream ends.

[0354] - When the current layer picture within the AU (access unit) associated with the PRI SEI message is output after the current picture in the output order.

[0355] pri_num_regions_minus1 + 1 represents the number of regions where information is signaled.

[0356] If pri_multilayer_flag is equal to 1, it indicates that the syntax element pri_region_layer_id[ i ] may exist in the PRI SEI message. If pri_multilayer_flag is equal to 0, it indicates that the syntax element pri_region_layer_id[ i ] may not exist in the PRI SEI message.

[0357] If pri_use_max_dimensions_flag is equal to 1, it indicates that MaxPicWidth, MaxPicHeight, PicWidthInLumaSamples, and PicHeightInLumaSamples can be used for variable calculations. If pri_use_max_dimensions_flag is equal to 0, it indicates that MaxPicWidth, MaxPicHeight, PicWidthInLumaSamples, and PicHeightInLumaSamples may not be used for variable calculations for region parameters.

[0358] pri_log2_unit_size represents the unit size used for variable calculations for area parameters.

[0359] The variable priUnitSize is set to 1 << pri_log2_unit_size.

[0360] pri_region_size_len_minus1 + 1 represents the number of bits used to signal pri_region_top_left_in_units_x[ i ], pri_region_top_left_in_units_y[ i ], pri_region_width_in_units_minus1[ i ], pri_region_height_in_units_minus1[ i ], pri_target_region_top_left_x[ i ], and pri_target_region_top_left_y[ i ].

[0361] If pri_region_id_present_flag is equal to 1, it indicates that the syntax element pri_region_id[ i ] may exist in the PRI SEI message. If pri_region_id_present_flag is equal to 0, it indicates that the syntax element pri_region_id[ i ] may not exist in the PRI SEI message.

[0362] Referring to Table 5 above, it can be seen that variables regarding chroma format indicators and bit depth are directly signaled in the PRI SEI message. Specifically, when a target picture parameter exists and the target picture parameter is updated, the variables regarding chroma format indicators and bit depth may be signaled.

[0363] The pri_target_pic_params_present_flag in Table 5 above may indicate whether the syntax elements pri_target_pic_param_update_flag, pri_target_region_top_left_x[ i ], pri_target_region_top_left_y[ i ], pri_target_pic_width_minus1, pri_target_pic_height_minus1, pri_target_pic_chroma_format_idc, pri_target_bitdepthy_minus8 and pri_target_bitdepthc_minus8 exist in the PRI SEI message.

[0364] pri_target_pic_params_present_flag with a value equal to 1 may indicate that the syntax elements pri_target_pic_param_update_flag, pri_target_region_top_left_x[ i ], pri_target_region_top_left_y[ i ], pri_target_pic_width_minus1, pri_target_pic_height_minus1, pri_target_pic_chroma_format_idc, pri_target_bitdepthy_minus8 and pri_target_bitdepthc_minus8 are present in the PRI SEI message.

[0365] pri_target_pic_params_present_flag with a value equal to 0 may indicate that the syntax elements pri_target_pic_param_update_flag, pri_target_region_top_left_x[ i ], pri_target_region_top_left_y[ i ], pri_target_pic_width_minus1, pri_target_pic_height_minus1, pri_target_pic_chroma_format_idc, pri_target_bitdepthy_minus8 and pri_target_bitdepthc_minus8 do not exist in the PRI SEI message.

[0366] Referring to Table 5 above, if the value of pri_target_pic_params_present_flag is equal to 1, pri_target_pic_param_update_flag can be signaled. If the value of pri_target_pic_param_update_flag is equal to 1, pri_target_pic_chroma_format_idc, which indicates the chroma format indicator of the target picture, and pri_target_bitdepthy_minus8, which is a variable regarding the luminance bit depth, can be signaled.

[0367] In addition, if the value of pri_target_pic_chroma_format_idc, which indicates the chroma format indicator of the target picture, is not 0, pri_target_bitdepthc_minus8, a variable regarding the chroma bit depth, can be signaled.

[0368] The above pri_target_pic_param_update_flag may indicate whether the parameters of the target picture are updated. In other words, pri_target_pic_param_update_flag may indicate whether the parameters of the target picture, including pri_target_pic_width_minus1, pri_target_pic_height_minus1, pri_target_pic_chroma_format_idc, pri_target_bitdepthy_minus8 and pri_target_bitdepthc_minus8, etc., are updated.

[0369] If pri_target_pic_width_minus1 + 1 and pri_target_pic_height_minus1 + 1 are present in the PRI SEI message, the width and height of the target picture that can be restored from samples of the cropped decoded picture corresponding to the regions described by this SEI message are indicated in units of luma samples.

[0370] The above pri_target_pic_chroma_format_idc represents chroma sampling relative to lumina sampling for a target display picture.

[0371] The value obtained by adding 8 to the above pri_target_bitdepthy_minus8 may represent the luma bit depth of the target picture. In this case, pri_target_bitdepthy_minus8 may be in the range of 0 to 8, and the variable targetBitDepthY representing the luma bit depth of the target picture may be set to be equal to pri_target_bitdepthy_minus8 + 8.

[0372] The value obtained by adding 8 to the above pri_target_bitdepthc_minus8 may represent the chroma bit depth of the target picture. In this case, pri_target_bitdepthc_minus8 may be in the range of 0 to 8, and the variable targetBitDepthC, which represents the chroma bit depth of the target picture, may be set to be equal to pri_target_bitdepthc_minus8 + 8.

[0373] pri_num_resampling_ratios_minus1 + 1 represents the number of resampling ratios being signaled.

[0374] pri_resampling_width_num_minus1[ i ] + 1 and pri_resampling_width_denom_minus1[ i ] + 1 represent the numerator and denominator, respectively, for width resampling of the i-th resampling ratio. pri_resampling_width_num_minus1[ i ] and pri_resampling_width_denom_minus1[ i ] may be values ​​within the range (inclusive) of 0 to 65535.

[0375] If the above syntax elements are not present in the PRI SEI message, the values ​​of pri_resampling_ratio_width_num_minus1

[0000] and pri_resampling_ratio_width_denom_minus1

[0000] are inferred to be equal to 0.

[0376] If pri_fixed_aspect_ratio_flag[ i ] is equal to 1, it indicates that the syntax elements pri_resampling_height_num_minus1[ i ] and pri_resampling_height_denom_minus1[ i ] may not exist in the PRI SEI message. If pri_fixed_aspect_ratio_flag[ i ] is equal to 0, it indicates that the syntax elements pri_resampling_height_num_minus1[ i ] and pri_resampling_height_denom_minus1[ i ] may exist in the PRI SEI message.

[0377] pri_resampling_height_num_minus1[ i ] + 1 and pri_resampling_height_denom_minus1[ i ] + 1 specify the numerator and denominator, respectively, for the height resampling of the i-th resampling ratio. The values ​​of pri_resampling_height_num_minus1[ i ] and pri_resampling_height_denom_minus1[ i ] can be values ​​within the range of 0 to 65535.

[0378] If the above syntax elements do not exist in the PRI SEI message, the values ​​of pri_resampling_height_num_minus1[ i ] and pri_resampling_height_denom_minus1[ i ] are inferred to be the same as pri_resampling_width_num_minus1[ i ] and pri_resampling_width_denom_minus1[ i ], respectively.

[0379] pri_region_id[ i ] represents the ID of the i-th region. If pri_region_id[ i ] does not exist in the PRI SEI message, the value of pri_region_id[ i ] is inferred to be the same as i.

[0380] pri_region_layer_id[ i ] represents a layer ID indicating which layer pri_region_top_left_in_units_x[ i ], pri_region_top_left_in_units_y[ i ], pri_region_width_in_units_minus1[ i ] and pri_region_height_in_units_minus1[ i ] relate to.

[0381] If pri_region_is_a_layer_flag[ i ] is equal to 1, it indicates that the picture width and picture height in the layer with ID pri_region_layer_id[ i ] are equal to the area width and area height of index i, and that pri_region_top_left_in_units_x[ i ], pri_region_top_left_in_units_y[ i ], pri_region_width_in_units_minus1[ i ] and pri_region_height_in_units_minus1[ i ] may not be signaled. If pri_region_is_a_layer_flag[ i ] does not exist, the value of pri_region_is_a_layer_flag[ i ] is inferred to be equal to 0.

[0382] pri_region_top_left_in_units_x[ i ] and pri_region_top_left_in_units_y[ i ] represent the horizontal and vertical positions, respectively, based on the unit of the top-left sample of the i-th region.

[0383] The length of the above syntax elements is pri_region_size_len_minus1 + 1.

[0384] Within a cropped decoded picture with layer identifier pri_region_layer_id[ i ], the variables priRegionTopLeftX[ i ] and priRegionTopLeftY[ i ], representing the horizontal and vertical positions in luma samples of the i-th region respectively, are derived as follows:

[0385] [Formula 5]

[0386] if(!pri_use_max_dimensions_flag) {

[0387] priRegionTopLeftX[ i ] = pri_region_top_left_in_units_x[ i ] * priUnitSize

[0388] priRegionTopLeftY[ i ] = pri_region_top_left_in_units_y[ i ] * priUnitSize

[0389] } else {

[0390] priRegionTopLeftX[ i ] = ( pri_region_top_left_in_units_x[ i ] * priUnitSize * PicWidthInLumaSamples + MaxPicWidth / 2 ) / MaxWidth

[0391] priRegionTopLeftY[ i ] = ( pri_region_top_left_in_units_y[ i ] * priUnitSize* PicHeightInLumaSamples + MaxPicHeight / 2 ) / MaxHeight

[0392] }

[0393] pri_region_width_in_units_minus1[ i ] + 1 and pri_region_height_in_units_minus1[ i ] + 1 represent the width and height of the i-th region, respectively, based on units. The length of the above syntax elements is pri_region_size_len_minus1 + 1.

[0394] The variables priRegionWidth[ i ] and priRegionHeight[ i ], representing the width and height in luma samples of the i-th region within the cropped decoded picture, respectively, are derived as follows:

[0395] [Equation 6]

[0396] if(!pri_use_max_dimensions_flag) {

[0397] priRegionWidth[ i ] = ( pri_region_width_in_units_minus1 [ i ] + 1) * priUnitSize

[0398] priRegionHeight[ i ] = ( pri_region_height_in_units_minus1 [ i ] + 1) * priUnitSize

[0399] } else {

[0400] priRegionWidth[ i ] = ( ( pri_region_width_in_units_minus1 [ i ] + 1) * priUnitSize * PicWidthInLumaSamples + MaxPicWidth / 2 ) / MaxWidth

[0401] priRegionHeight[ i ] = ( ( pri_region_height_in_units_minus1 [ i ] + 1) * priUnitSize * PicHeightInLumaSamples + MaxPicHeight / 2 ) / MaxHeight

[0402] }

[0403] The above SubWidthC and SubHeightC variables can be derived from pri_target_pic_chroma_format_idc of the present embodiment. That is, the above SubWidthC and SubHeightC variables can be derived from pri_target_pic_chroma_format_idc explicitly signaled in the PRI SEI message.

[0404] The requirement for bitstream conformity is that priRegionWidth[ i ] % SubWidthC is equal to 0 and priRegionHeight[ i ] % SubHeightC is equal to 0.

[0405] pri_resampling_ratio_idx[ i ] represents the index of the resampling ratio used for the i-th region. The length of the above syntax element is Ceil(Log2(pri_num_resampling_ratios_minus1 + 1)).

[0406] The variables priResampleWidthNum[ i ], priResampleWidthDenom[ i ], priResampleHeightNum[ i ], and priResampleHeightDenom[ i ] are derived as follows:

[0407] priResampleWidthNum[ i ] = pri_resampling_width_num_minus1[ pri_resampling_ratio_idx[ i ] ] + 1

[0408] priResampleWidthDenom[ i ] = pri_resampling_width_denom_minus1[ pri_resampling_ratio_idx[ i ] ] + 1

[0409] priResampleHeightNum[ i ] = pri_resampling_height_num_minus1[ pri_resampling_ratio_idx[ i ] ] + 1

[0410] priResampleHeightDenom[ i ] = pri_resampling_height_denom_minus1[ pri_resampling_ratio_idx[ i ] ] + 1

[0411] If pri_target_region_top_left_x[ i ] and pri_target_region_top_left_y[ i ] exist in the PRI SEI message, the horizontal and vertical positions of the top left sample position of the i-th region within the reconstructed target picture are indicated in units of luminous samples, respectively.

[0412] The variables priTargetRegionWidth and priTargetRegionHeight, representing the width and height of the resampled region within the reconstructed target picture in luma samples, respectively, are derived as follows:

[0413] priTargetRegionWidth = Round( ( priRegionWidth[ i ] * priResampleWidthNum[ i ] ) / ( priResampleWidthDenom[ i ] * SubWidthC ) ) * SubWidthC

[0414] priTargetRegionHeight = Round( ( priRegionHeight[ i ] * priResampleHeightNum[ i ] ) / ( priResampleHeightDenom[ i ] * SubHeightC ) ) * SubHeightC

[0415] When restoring a target picture with a luminar sample array size of ( pri_target_pic_width_minus1 + 1 ) × ( pri_target_pic_height_minus1 + 1 ) all luminar sample values ​​can be initialized to 1 << ( targetBitDepthY - 1 ) and if chroma samples exist, those chroma samples can be initialized to 1 << ( targetBitDepthC - 1 ) . That is, the values ​​of the luminar samples and chroma samples used when restoring the target picture can be initialized based on targetBitDepthY and targetBitDepthC of the present embodiment.

[0416] For sample position (x, y) and regions j and k, if all of the following conditions are satisfied, the reconstructed target picture sample at position (x, y) is determined by the parameters signaled for the j-th region.

[0417] -pri_region_id[j] > pri_region_id[k]

[0418] -x is in (priRegionTopLeftX[ j ] .. priRegionTopLeftX[ j ] + priRegionWidth[ j ])

[0419] -y is in (priRegionTopLeftY[ j ] .. priRegionTopLeftY[ j ] + priRegionHeight[ j ])

[0420] -x is in (priRegionTopLeftX[ k ] .. priRegionTopLeftX[ k ] + priRegionWidth[ k])

[0421] -y is in (priRegionTopLeftY[ k ] .. priRegionTopLeftY[ k ] + priRegionHeight[ k ])

[0422] The following variables are defined to interpret the PRI SEI message:

[0423] -PicWidthInLumaSamples can be set to the same value as pps_pic_width_in_luma_samples - SubWidthC * ( pps_conf_win_left_offset + pps_conf_win_right_offset )

[0424] -PicHeightInLumaSamples can be set to the same value as pps_pic_height_in_luma_samples - SubHeightC * ( pps_conf_win_top_offset + pps_conf_win_bottom_offset )

[0425] -MaxPicWidth can be set to the value of sps_pic_width_in_luma_samples - SubWidthC * ( sps_conf_win_left_offset + sps_conf_win_right_offset )

[0426] -MaxPicHeight can be set to the value of sps_pic_height_in_luma_samples - SubHeightC * ( sps_conf_win_top_offset + sps_conf_win_bottom_offset )

[0427] In this way, the chroma format indicator and bit depth for the target picture can be explicitly signaled. Additionally, the chroma format indicator and bit depth can be signaled based on the target picture parameters.

[0428] FIG. 7 is a diagram illustrating a method for decoding image information according to one embodiment.

[0429] 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.

[0430] 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).

[0431] 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.

[0432] 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.

[0433] Referring to FIG. 7, a method for decoding image information according to one embodiment may include the step of obtaining image information including a packed regions information (PRI) SEI message from a bitstream (S1010), and the step of obtaining a first flag indicating whether a parameter of a target picture exists from the packed regions information (PRI) SEI message (S1020).

[0434] The PRI SEI message obtained according to the method of FIG. 7 above may include some or all of the syntax of Tables 4 and 5 described above. Accordingly, the PRI SEI message described in step S1010 may be the PRI SEI message described in Tables 4 and 5 above, and the contents described above with reference to Tables 4 and 5 may also be applied to this embodiment.

[0435] For example, the method may include obtaining information indicating the relationship between chroma sampling and lumina sampling of a target picture and information indicating the lumina bit depth of a target picture based on the first flag value, and obtaining information indicating the chroma bit depth of a target picture based on the information value indicating the relationship between chroma sampling and lumina sampling of a target picture.

[0436] The first flag above may represent pri_target_pic_params_present_flag, which indicates whether the parameter syntax element of the target picture exists in the PRI SEI message.

[0437] In other words, based on the value of pri_target_pic_params_present_flag, information indicating the relationship between chroma sampling and lumina sampling of a target picture and information indicating the lumina bit depth of a target picture may be obtained, and based on the value of the information indicating the relationship between chroma sampling and lumina sampling of a target picture, information indicating the chroma bit depth of a target picture may be obtained.

[0438] Specifically, based on the value of pri_target_pic_params_present_flag being 1, information indicating the relationship between chroma sampling and lumina sampling of the target picture and information indicating the lumina bit depth of the target picture can be obtained.

[0439] Additionally, the method may include a method for obtaining information representing the chroma bit depth of the target picture based on the fact that the information value representing the relationship between the luminance sampling and the chroma sampling of the target picture is not zero.

[0440] Meanwhile, based on the first flag value above, a method for obtaining information indicating the top-left position of rectangular regions within a target picture may be included.

[0441] Meanwhile, based on the first flag value, a method for obtaining information indicating the width of the target picture and information indicating the height of the target picture may be included.

[0442] Thus, when target picture parameters exist, the chroma format indicator and bit depth can be explicitly signaled.

[0443] FIG. 8 is a diagram illustrating a method for encoding image information according to one embodiment.

[0444] 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.

[0445] 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).

[0446] 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.

[0447] 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.

[0448] Referring to FIG. 8, a method for encoding image information according to one embodiment may include the step of generating parameter information of a target picture and a first flag indicating whether parameter information of the target picture exists (S1110), the step of generating a packed regions information (PRI) SEI message containing parameter-related information of the target picture (S1120), and the step of encoding image information containing the packed regions information (PRI) SEI message (S1130).

[0449] The PRI SEI message generated according to the method of FIG. 8 above may include some or all of the syntax of Tables 4 and 5 described above. Accordingly, the PRI SEI message described in step S1120 may be the PRI SEI message described in Table 4 or Table 5, and the contents described above with reference to Table 4 or Table 5 may also be applied to this embodiment.

[0450] For example, based on the first flag value, information indicating the relationship between chroma sampling and lumina sampling of the target picture and information indicating the lumina bit depth of the target picture are included in the parameter-related information of the target picture, and based on the information value indicating the relationship between chroma sampling and lumina sampling of the target picture, information indicating the chroma bit depth of the target picture is included in the parameter-related information of the target picture.

[0451] The first flag above may represent pri_target_pic_params_present_flag, which indicates whether the parameter syntax element of the target picture exists in the PRI SEI message.

[0452] In other words, based on the value of pri_target_pic_params_present_flag, information indicating the relationship between chroma sampling and lumina sampling of the target picture and information indicating the lumina bit depth of the target picture are included in the parameter-related information of the target picture, and based on the value of the information indicating the relationship between chroma sampling and lumina sampling of the target picture, information indicating the chroma bit depth of the target picture is included in the parameter-related information of the target picture.

[0453] Specifically, based on the value of pri_target_pic_params_present_flag being 1, information indicating the relationship between chroma sampling and lumina sampling of the target picture and information indicating the lumina bit depth of the target picture may be included in the parameter-related information of the target picture.

[0454] In addition, based on the fact that the information value representing the relationship between chroma sampling and lumina sampling of the target picture is not zero, information representing the chroma bit depth of the target picture may be included in the parameter-related information of the target picture.

[0455] Meanwhile, based on the first flag value, information indicating the top-left position of rectangular regions within the target picture may be included in the parameter-related information of the target picture.

[0456] Meanwhile, based on the first flag value, information indicating the width of the target picture and information indicating the height of the target picture may be included in the parameter-related information of the target picture.

[0457] Thus, when target picture parameters exist, the chroma format indicator and bit depth can be explicitly signaled.

[0458] FIG. 9 is a diagram illustrating a method for decoding image information according to one embodiment.

[0459] Referring to FIG. 9, a method for decoding image information according to one embodiment may include the step of obtaining a first flag indicating whether parameter information of a target picture exists from a PRI SEI message (S1210), and the step of obtaining a second flag indicating whether parameter information of the target picture is updated based on the value of the first flag (S1220).

[0460] The PRI SEI message obtained according to the method of FIG. 9 above may include some or all of the syntax of Tables 4 and 5 described above. Accordingly, the first flag and the second flag described in steps S1210 and S1220 may be syntax included in the PRI SEI message described in Tables 4 and 5, and the contents described above with reference to Tables 4 and 5 may also be applied to this embodiment.

[0461] For example, the second flag can be obtained based on the first flag value, and information indicating the relationship between chroma sampling and lumina sampling of the target picture and information indicating the lumina bit depth of the target picture can be obtained based on the second flag value. Additionally, the method may include obtaining information indicating the chroma bit depth of the target picture based on the information value indicating the relationship between chroma sampling and lumina sampling of the target picture.

[0462] That is, based on the values ​​of the first flag and the second flag, the method may include obtaining information indicating the relationship between chroma sampling and lumina sampling of the target picture and information indicating the lumina bit depth of the target picture.

[0463] The first flag above may represent pri_target_pic_params_present_flag of Table 5 above, and the second flag above may represent pri_target_pic_param_update_flag of Table 5 above.

[0464] For example, a method for obtaining the second flag based on the first flag value being 1 may be included.

[0465] Additionally, based on the second flag value being 1, the method may include information indicating the relationship between chroma sampling and lumina sampling of the target picture and information indicating the lumina bit depth of the target picture.

[0466] Additionally, the method may include a method for obtaining information representing the chroma bit depth of the target picture based on the fact that the information value representing the relationship between the luminance sampling and the chroma sampling of the target picture is not zero.

[0467] FIG. 10 is a diagram illustrating a method for encoding image information according to one embodiment.

[0468] Referring to FIG. 10, a method for encoding image information according to one embodiment may include the step of generating parameter information of a target picture (S1310), the step of generating a first flag indicating whether parameter information of the target picture exists and a second flag indicating whether parameter information of the target picture is updated (S1320), and the step of encoding information related to the parameters of the target picture (S1330).

[0469] The information related to the parameters of the target picture may include the parameter information of the target picture, a first flag indicating whether the parameter information of the target picture exists, and a second flag indicating whether the parameter information of the target picture is updated.

[0470] The parameter information of the target picture generated according to the method of FIG. 10 may include some or all of the syntax of Tables 4 and 5 described above. Accordingly, the parameter information of the target picture described in step S1310 and the first flag and the second flag described in S1320 may be the syntax included in the PRI SEI message described in Tables 4 and 5, and the contents described above with reference to Tables 4 and 5 may also be applied to this embodiment.

[0471] For example, the second flag may be generated based on the first flag value, and information indicating the relationship between chroma sampling and lumina sampling of the target picture and information indicating the lumina bit depth of the target picture may be included in the parameter-related information of the target picture based on the second flag value. Additionally, information indicating the chroma bit depth of the target picture may be included in the parameter-related information of the target picture based on the information value indicating the relationship between chroma sampling and lumina sampling of the target picture.

[0472] That is, based on the values ​​of the first flag and the second flag, information indicating the relationship between chroma sampling and lumina sampling of the target picture and information indicating the lumina bit depth of the target picture may be included in the parameter-related information of the target picture.

[0473] The first flag above may represent pri_target_pic_params_present_flag of Table 5 above, and the second flag above may represent pri_target_pic_param_update_flag of Table 5 above.

[0474] For example, the second flag may be generated based on the first flag value being 1.

[0475] Additionally, based on the second flag value being 1, information indicating the relationship between chroma sampling and lumina sampling of the target picture and information indicating the lumina bit depth of the target picture may be included in the parameter-related information of the target picture.

[0476] In addition, based on the fact that the information value representing the relationship between chroma sampling and lumina sampling of the target picture is not zero, information representing the chroma bit depth of the target picture may be included in the parameter-related information of the target picture.

[0477] 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.

[0478] 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.

[0479] Additionally, 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 encoding method, and the generated bitstream may be transmitted through the transmission unit.

[0480] FIG. 11 is a drawing illustrating an exemplary content streaming system to which an embodiment according to the present disclosure can be applied.

[0481] 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.

[0482] 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.

[0483] 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.

[0484] 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.

[0485] 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.

[0486] 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.

[0487] 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.

[0488] 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.

[0489] An embodiment according to the present disclosure can be used to encode / decode images.

Claims

1. A step of acquiring image information including packed regions information (PRI) SEI messages from a bitstream; and The method includes the step of obtaining a first flag indicating whether parameter information of a target picture exists from the packed regions information (PRI) SEI message. Based on the first flag value above, information indicating the relationship between chroma sampling and lumina sampling of the target picture and information indicating the lumina bit depth of the target picture are obtained, A method for obtaining information representing the chroma bit depth of a target picture based on an information value representing the relationship between chroma sampling and lumina sampling of the target picture.

2. In Paragraph 1, A method for obtaining information indicating the chroma bit depth of a target picture based on the fact that an information value indicating the relationship between chroma sampling and lumina sampling of the target picture is not zero.

3. In Paragraph 1, A method comprising obtaining information indicating the top-left position of rectangular regions within a target picture based on the first flag value.

4. In Paragraph 1, A method comprising obtaining information indicating the width of the target picture and information indicating the height of the target picture based on the first flag value.

5. In Paragraph 1, A method further comprising the step of obtaining a second flag indicating whether parameter information of the target picture is updated based on the first flag value.

6. In Paragraph 5, A method for obtaining the second flag based on the first flag value being 1.

7. In Paragraph 5, A method for obtaining information indicating the relationship between chroma sampling and lumina sampling of the target picture and information indicating the lumina bit depth of the target picture, based on the values ​​of the first flag and the second flag.

8. In Paragraph 5, A method for obtaining information indicating the relationship between chroma sampling and lumina sampling of the target picture and information indicating the lumina bit depth of the target picture, based on the fact that the values ​​of the first flag and the second flag are 1.

9. In Paragraph 8, A method for obtaining information indicating the chroma bit depth of a target picture based on the fact that an information value indicating the relationship between chroma sampling and lumina sampling of the target picture is not zero.

10. A step of generating parameter information of a target picture and a first flag indicating whether parameter information of the target picture exists; A step of generating a packed regions information (PRI) SEI message containing parameter-related information of the target picture; and The method includes the step of encoding image information containing the packed regions information (PRI) SEI message; and Based on the first flag value above, information indicating the relationship between chroma sampling and lumina sampling of the target picture and information indicating the lumina bit depth of the target picture are included in the parameter-related information of the target picture, and A method in which information representing the chroma bit depth of a target picture is included in parameter-related information of the target picture, based on an information value representing the relationship between chroma sampling and lumina sampling of the target picture.

11. 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, A step of generating a packed regions information (PRI) SEI message containing parameter-related information of a target picture; and The method includes the step of encoding image information containing the packed regions information (PRI) SEI message; and A first flag indicating whether parameter information of the target picture exists is included in the parameter-related information of the target picture, and Based on the first flag value above, information indicating the relationship between chroma sampling and lumina sampling of the target picture and information indicating the lumina bit depth of the target picture are included in the parameter-related information of the target picture, and A method in which information representing the chroma bit depth of a target picture is included in parameter-related information of the target picture, based on an information value representing the relationship between chroma sampling and lumina sampling of the target picture.

Images