Method and computer-readable storage medium

Abstract

A method according to one aspect comprises the steps of: acquiring, from a bitstream, image information including an image format metadata-related message; and deriving a type of an image format metadata payload on the basis of payload type-related information included in the image format metadata-related message, wherein a value of the payload type-related information is included in a range of 0 to 6.

Description

Method and computer-readable storage medium

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

[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 provides a method to prevent unnecessary memory usage or misinterpretation of SEI messages by a syntax element indicating the type of an image format metadata payload.

[0005] In addition, the present disclosure provides a method to prevent the occurrence of problems related to misinterpretation of SEI messages or future version extensions by establishing processing rules for values ​​within an unacceptable range.

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

[0007] A method according to one aspect comprises: a step of obtaining image information including a message related to image format metadata from a bitstream; and a step of deriving a type of image format metadata payload based on information related to a payload type included in the message related to image format metadata, wherein the value of the information related to the payload type is included in a range from 0 to 6.

[0008] The information related to the payload type having values ​​from 7 to 255 does not exist in the bitstream.

[0009] The value of the above payload type related information has a constraint that it must be included in the range from 0 to 6.

[0010] Based on the fact that the value of the above payload type related information is included in the range from 7 to 255, information regarding the image format metadata payload corresponding to the above payload type related information is ignored.

[0011] Based on the fact that the value of the above payload type related information is included in the range from 7 to 255, the above payload type related information is ignored.

[0012] A method according to one aspect comprises: a step of generating payload type related information based on the type of image metadata payload; a step of generating an image format metadata related message including the payload type related information; and a step of encoding image information including the image format metadata related message into a bitstream; wherein the value of the payload type related information is included in the range from 0 to 6.

[0013] The information related to the payload type having values ​​from 7 to 255 does not exist in the bitstream.

[0014] The value of the above payload type related information has a constraint that it must be included in the range from 0 to 6.

[0015] A computer-readable storage medium according to one aspect can non-transiently store a bitstream generated by the above method.

[0016] A method according to one aspect comprises: a step of generating a bitstream; and a step of transmitting data including the bitstream; wherein the step of generating the bitstream comprises: a step of generating payload type related information based on the type of image metadata payload; a step of generating an image format metadata related message including the payload type related information; and a step of encoding image information including the image format metadata related message; and wherein the value of the payload type related information is included in the range from 0 to 6.

[0017] 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.

[0018] According to an embodiment of the present disclosure, by imposing a restriction on the range of values ​​of a syntax element indicating the type of an image format metadata payload, unnecessary memory usage or incorrect interpretation of SEI messages can be prevented.

[0019] In addition, the present disclosure can prevent the occurrence of problems related to misinterpretation of SEI messages or future version extensions by providing processing rules for values ​​within an unacceptable range.

[0020] 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.

[0021] FIG. 1 is a schematic diagram illustrating a video coding system to which an embodiment according to the present disclosure can be applied.

[0022] FIG. 2 is a schematic diagram showing an encoding device to which an embodiment according to the present disclosure can be applied.

[0023] FIG. 3 is a schematic diagram showing a decoding device to which an embodiment according to the present disclosure can be applied.

[0024] FIG. 4 shows an example of a video / image decoding method to which one embodiment can be applied.

[0025] FIG. 5 shows an example of a video / image encoding method to which an embodiment of the present disclosure can be applied.

[0026] Figure 6 illustrates an exemplary hierarchical structure for a coded video / image.

[0027] FIG. 7 is a diagram illustrating a method for decoding image information according to one embodiment.

[0028] FIG. 8 is a diagram illustrating a method for encoding image information according to one embodiment.

[0029] FIG. 9 is a drawing illustrating an exemplary content streaming system to which an embodiment according to the present disclosure can be applied.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] The present disclosure relates to the encoding and decoding of images. For example, the methods and embodiments disclosed in this document may be applied to methods disclosed in the VVC (Versatile Video Coding) standard, VSEI (Versatile Supplemental Enhancement Information), HEVC (High Efficiency Video Coding) standard, EVC (Essential Video Coding) standard, AV1 (AOMedia Video 1) standard, AVC (Advanced Video Coding) standard, AVS2 (2nd generation of audio-video coding standard), or next-generation video / image coding standards (e.g., H.267 or H.268, etc.). However, the aforementioned standards are merely examples to which the methods according to the present disclosure are applicable, and it is understood that they may also be applied to other video coding technologies.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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."

[0043] 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."

[0044] 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."

[0045] 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".

[0046] In the present disclosure, "at least one A, B, and C" may mean "only A," "only B," "only C," or "any combination of two or more selected from the group consisting of A, B, and C." Additionally, "at least one A, B, or C" or "at least one A, B, and / or C" may mean "at least one A, B, and C."

[0047] FIG. 1 is a schematic diagram illustrating a video / image coding system to which an embodiment according to the present disclosure can be applied.

[0048] 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.

[0049] 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.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] 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.

[0054] The renderer can render the decoded video / image. The rendered video / image can be displayed through the display unit.

[0055] FIG. 2 is a schematic diagram illustrating an encoding device to which an embodiment according to the present disclosure can be applied.

[0056] 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 a 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 components may further include the memory (270) as an internal / external component.

[0057] 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.

[0058] 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.

[0059] 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.

[0060] 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.

[0061] 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.

[0062] 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.

[0063] The prediction signal generated through the prediction unit (220) can be used to generate a restoration signal or to generate a residual signal. The subtraction unit (231) can generate a residual signal (residual signal, residual block, residual sample array) by subtracting the prediction signal (predicted block, prediction sample array) output from the prediction unit (220) from the input image signal (original block, original sample array). The generated residual signal can be transmitted to the conversion unit (232).

[0064] 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.

[0065] 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.

[0066] 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, in addition to quantized transform coefficients. The encoded information (e.g., encoded video / image information) may be transmitted or stored in the form of a bitstream in units of NAL (network abstraction layer) units. The video / image information may further include information regarding various parameter sets, such as an adaptation parameter set (APS), a picture parameter set (PPS), a sequence parameter set (SPS), or a video parameter set (VPS). Additionally, the video / image information may further include general constraint information. The signaling information, transmitted information, and / or syntax elements mentioned in the present disclosure may be included in the video / image information. The video / image information may be encoded through the encoding procedure described above and included in the bitstream.

[0067] 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).

[0068] 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).

[0069] Meanwhile, LMCS (luma mapping with chroma scaling) may be applied during the picture encoding and / or restoration process.

[0070] 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.

[0071] 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.

[0072] 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.

[0073] 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).

[0074] FIG. 3 is a schematic diagram illustrating a decoding device to which an embodiment according to the present disclosure can be applied.

[0075] As illustrated in FIG. 3, the decoding device (300) may be configured to include an entropy decoder (310), a residual processor (320), a predictor (330), an adder (340), a filter (350), and a memory (360). The predictor (330) may include an inter-predictor (332) and an intra-predictor (331). The residual processor (320) may include a dequantizer (321) and an inverse transformer (321). The aforementioned entropy decoding unit (310), residual processing unit (320), prediction unit (330), addition unit (340), and filtering unit (350) may be configured by a single hardware component (e.g., a decoder chipset or a processor) according to an embodiment. Additionally, the memory (360) may include a decoded picture buffer (DPB) and may be configured by a digital storage medium. The hardware component may further include the memory (360) as an internal / external component.

[0076] When a bitstream containing video / image information is input, the decoding device (300) can restore the image by performing a process corresponding to the process performed by the encoding device (200) of FIG. 2. For example, the decoding device (300) can perform decoding using a processing unit applied in the encoding device (200). Thus, the processing unit for decoding may be, for example, a coding unit. The coding unit may be a coding tree unit, or a maximum coding unit may be obtained by dividing it according to a quad tree structure, a binary tree structure, and / or a binary tree structure. And, the restored image signal decoded and output through the decoding device (300) can be played back through a playback device (not shown).

[0077] 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).

[0078] 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.

[0079] In the inverse conversion unit (322), the conversion coefficients can be inversely converted to obtain a residual signal (residual block, residual sample array).

[0080] 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.

[0081] The intra prediction unit (331) can predict the current block by referring to samples within the current picture. The description of the intra prediction unit (222) may be applied equally to the intra prediction unit (331). The referenced samples may be located in the neighborhood of the current block or located away from it, depending on the prediction mode. In intra prediction, the prediction modes may include a plurality of non-directional modes and a plurality of directional modes. The intra prediction unit (331) may determine the prediction mode applied to the current block by using the prediction mode applied to the neighboring blocks.

[0082] 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.

[0083] The adder (340) can generate a restoration signal (restored picture, restored block, restored sample array) by adding the acquired residual signal to the prediction signal (predicted block, predicted sample array) output from the prediction unit (330) (including the inter prediction unit (332) and / or intra prediction unit (331)). In cases where there is no residual for the block to be processed, such as when a skip mode is applied, the predicted block can be used as the restoration block. The description of the adder (250) can be applied equally to the adder (340). The adder (340) may be called a restoration unit or a restoration block generation unit. The generated restoration signal can be used for intra prediction of the next block to be processed within the current picture, and can also be used for inter prediction of the next picture after undergoing filtering as described below.

[0084] Meanwhile, LMCS (luma mapping with chroma scaling) may be applied during the picture decoding process.

[0085] 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.

[0086] 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).

[0087] 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.

[0088] A video / image coding method according to the present disclosure may be performed based on the following partitioning structure. Specifically, the procedures described below, such as prediction, residual processing ((inverse)transform, (inverse)quantization, etc.), syntax element coding, and filtering, may be performed based on CTU and CU (and / or TU, PU) derived based on the partitioning structure. The block partitioning procedure may be performed in the image segmentation unit (210) of the encoding device described above, and the partitioning-related information may be processed (encoded) in the entropy encoding unit (240) and transmitted to the decoding device in the form of a bitstream. The entropy decoding unit (310) of the decoding device may derive the block partitioning structure of the current picture based on the partitioning-related information obtained from the bitstream, and perform a series of procedures for image decoding (e.g., prediction, residual processing, block / picture restoration, in-loop filtering, etc.) based thereon. The CU size and the TU size may be the same, or multiple TUs may exist within the CU area. Meanwhile, the term CU size generally refers to the CB size of the luminous component (sample). The term TU size generally refers to the TB size of the luminous component (sample).

[0089] The chroma component (sample) CB or TB size can be derived based on the luminance component (sample) CB or TB size according to the component ratio based on the color format (chroma format, e.g., 4:4:4, 4:2:2, 4:2:0, etc.) of the picture / image. The TU size can be derived based on maxTbSize. For example, if the CU size is larger than the maxTbSize, multiple TUs (TBs) of the maxTbSize are derived from the CU, and conversion / inverse conversion can be performed in units of the TU (TB). Additionally, for example, when intra prediction is applied, the intra prediction mode / type is derived in units of the CU (or CB), and the procedure for deriving surrounding reference samples and generating prediction samples can be performed in units of the TU (or TB). In this case, one or more TUs (or TBs) may exist within a single CU (or CB) region, and in this case, the multiple TUs (or TBs) may share the same intra prediction mode / type.

[0090] Additionally, in the coding of video / image according to the present disclosure, the image processing unit may have a hierarchical structure. A picture may be divided into one or more tiles, bricks, slices, and / or tile groups. A slice may include one or more bricks. A brick may include one or more CTU rows within the tile. A slice may include an integer number of bricks in the picture. A tile group may include one or more tiles. A tile may include one or more CTUs. The CTU may be divided into one or more CUs. A tile is a rectangular area within a picture that includes CTUs within a specific tile row and a specific tile column. A tile group may include an integer number of tiles according to a tile raster scan within the picture. A slice header may carry information / parameters that can be applied to the corresponding slice (blocks within the slice). If the encoding / decoding device has a multi-core processor, the encoding / decoding procedure for the tile, slice, brick, and / or tile group may be processed in parallel.

[0091] In the present disclosure, slices or tile groups may be used interchangeably. That is, a tile group header may be referred to as a slice header. Here, a slice may have one of the slice types including an intra (I) slice, a predictive (P) slice, and a bi-predictive (B) slice. For blocks within an I slice, only intra prediction may be used for prediction, and no inter prediction may be used. Of course, even in this case, the original sample value may be coded and signaled without prediction. For blocks within a P slice, intra prediction or inter prediction may be used, and if inter prediction is used, only uni prediction may be used. Meanwhile, for blocks within a B slice, intra prediction or inter prediction may be used, and if inter prediction is used, up to bi-prediction may be used.

[0092] In an encoding device, tile / tile group, brick, slice, and maximum and minimum coding unit sizes are determined based on video characteristics (e.g., resolution) or by considering coding efficiency or parallel processing, and information regarding this or information that can derive it may be included in the bitstream.

[0093] The decoding device can obtain information indicating whether the tile / tile group, brick, slice, or CTU within the tile of the current picture has been divided into multiple coding units. Efficiency can be increased by obtaining (transmitting) this information only under specific conditions.

[0094] The slice header (slice header syntax) 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 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 the CVS (coded video sequence).

[0095] In the present disclosure, the term "higher-level syntax" may include at least one of the APS syntax, PPS syntax, SPS syntax, VPS syntax, DPS syntax, and slice header syntax.

[0096] In addition, for example, information regarding the division and configuration of the above tile / tile group / brick / slice can be configured at the encoding stage through the above-mentioned upper-level syntax and transmitted to the decoding device in the form of a bitstream.

[0097] Pictures can be divided into sequences of Coding Tree Units (CTUs). A CTU may correspond to a Coding Tree Block (CTB). Alternatively, a CTU may include a Coding Tree Block of Luma Samples and two Coding Tree Blocks of corresponding Chroma Samples. In other words, for a picture containing three sample arrays, a CTU may include an NxN block of Luma Samples and two corresponding blocks of Chroma Samples.

[0098] The maximum allowable size of a CTU for coding and prediction, etc., may differ from the maximum allowable size of a CTU for transformation. For example, the maximum allowable size of a luminance block within a CTU may be 128x128 (even though the maximum size of luminance ring blocks is 64x64).

[0099] A picture is divided into one or more tile rows and one or more tile columns. A tile is a sequence of CTUs covering a rectangular area of ​​the picture. The CTUs within a tile are scanned in raster scan order within that tile.

[0100] A slice consists of an integer number of complete tiles within a picture or an integer number of consecutive complete CTU rows within a single tile. Two modes are supported for slicing: raster-scan slice mode and rectangular slice mode.

[0101] In raster-scan slice mode, a slice comprises a sequence of complete tiles according to the tile raster scan order of the picture. In rectangular slice mode, a slice comprises a number of complete tiles collectively configured to form a rectangular area of ​​the picture, or a number of consecutive complete CTU rows that collectively form a rectangular area within a single tile. The tiles within a rectangular slice are scanned in the tile raster scan order within the rectangular area corresponding to that slice.

[0102] A subpicture includes one or more slices that collectively cover a rectangular area of ​​a picture. For example, it is possible for a picture to be divided into 28 subpictures of different sizes.

[0103] When a picture is encoded into three separate color planes (where separate_colour_plane_flag is 1), the slice contains only CTUs of a single color component identified by the corresponding value of colour_plane_id, and each array of color components of the picture consists of slices having the same colour_plane_id value.

[0104] Encoded slice NAL units having different colour_plane_id values ​​within a picture can be interleaved with respect to each colour_plane_id value, provided that for each colour_plane_id value, the encoded slice NAL units having that colour_plane_id value are arranged in an order of increasing CTU addresses in the tile scan order for the first CTU of each slice NAL unit.

[0105] Meanwhile, when separate_colour_plane_flag is 0, each CTU of the picture is contained in exactly one slice. When separate_colour_plane_flag is 1, the CTU of each color component is contained in exactly one slice (i.e., information for each CTU of the picture is contained in exactly three slices, and these three slices have different colour_plane_id values).

[0106] Tiles change the order of CTUs within a picture. If a picture is divided into two or more tiles, the order of CTUs becomes the raster-scan order within each tile, which can be exemplified by a case where the picture is divided into two tiles and each tile has 8 CTUs. Note that the CTUs are arranged in raster-scan order within each tile.

[0107] FIG. 4 shows an example of a video / image decoding method to which one embodiment can be applied.

[0108] 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.

[0109] 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.

[0110] 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).

[0111] 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.

[0112] 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.

[0113] FIG. 5 shows an example of a video / image encoding method to which an embodiment of the present disclosure can be applied.

[0114] 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.

[0115] 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.

[0116] 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.

[0117] 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.

[0118] 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.

[0119] 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.

[0120] 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.

[0121] Figure 6 illustrates an exemplary hierarchical structure for a coded video / image.

[0122] 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.

[0123] 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.

[0124] 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.

[0125] 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).

[0126] 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.

[0127] 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.

[0128] 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.

[0129] 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.

[0130] - APS (Adaptation Parameter Set) NAL unit: Type for the NAL unit containing the APS

[0131] - DPS(Decoding Parameter Set) NAL unit: Type for the NAL unit containing the DPS

[0132] - VPS (Video Parameter Set) NAL unit: Type for the NAL unit containing the VPS

[0133] - SPS (Sequence Parameter Set) NAL unit: Type for NAL unit containing SPS

[0134] - PPS(Picture Parameter Set) NAL unit: Type for the NAL unit containing the PPS

[0135] 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.

[0136] 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.

[0137] 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.

[0138] 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).

[0139] Hereinafter, SEI messages related to embodiments of the present disclosure will be described.

[0140] An embodiment according to the present disclosure relates to an image format metadata SEI message.

[0141] The video format metadata SEI message can specify an SEI message in which the payload of EXIF, JFIF, XMP, and ICC profile video format metadata can be transmitted within the video bitstream. The following describes the various syntax elements included in the video format metadata SEI message, referring to the syntax examples in Table 1 below.

[0142] [Table 1]

[0143]

[0144] ifm_cancel_flag can indicate whether the persistence of all previous image format metadata SEI messages in the output order is canceled. ifm_cancel_flag equal to 1 can indicate that the persistence of all previous image format metadata SEI messages in the output order is canceled. ifm_cancel_flag equal to 0 can indicate that image format information follows.

[0145] ifm_persistence_flag can specify the persistence of image format metadata SEI messages for the current layer. ifm_persistence_flag equal to 0 can specify that image format metadata SEI messages apply only to the currently decoded picture. ifm_persistence_flag equal to 1 can specify that image format metadata SEI messages apply to the currently decoded picture and persist to all subsequent pictures of the current layer in the output order until one or more of the following conditions are true:

[0146] - When a new CLVS of the current layer starts

[0147] - When the bitstream ends

[0148] - When the picture of the current layer included in the AU (Access Unit) associated with the video format metadata SEI message is output, and that picture is positioned after the current picture in the output order.

[0149] ifm_num_metadata_payloads can represent the number of subsequent image format metadata payloads.

[0150] ifm_bit_equal_to_zero must be equal to 0.

[0151] ifm_type_id[i] can represent the type of the i-th image format metadata payload as defined in Table 2 below.

[0152] [Table 2]

[0153]

[0154] If ifm_type_id[ i ] is equal to 0, the following image metadata payload may be Exchangeable Image File (Exif) attribute information. For example, it may include a tag with id 0x8769 (ExifTag) as a TIFF data structure compliant with TIFF revision 6.0. Exif attribute information for a digital still camera may include a set of metadata that captures information about the digital photography process used to record the image. This metadata may include the camera's acceleration vector at the time the image was captured, camera lens information, GPS data, the color space used, spectral sensitivity, the lens's maximum aperture value, etc.

[0155] If ifm_type_id[ i ] is equal to 1, 2 or 3, the i-th image format metadata payload may be JFIF metadata specified by ITU-T Recommendation T.871 | ISO / IEC International Standard 10918-5. JFIF metadata and its semantics may be specified by ITU-T Recommendation T.871 | ISO / IEC International Standard 10918-5 (hereinafter JFIF Standard). In JFIF, JFIF markers containing information describing the composition of image data and JFIF markers containing extension information may be distinguished.

[0156] If ifm_type_id[ i ] is equal to 1, the i-th image format metadata payload may contain JFIF metadata from one or more concatenated JFIF marker segments, excluding the APP0 marker segment identifier itself, as specified in ITU-T Recommendation T.871 | International Standard ISO / IEC 10918-5.

[0157] If ifm_type_id[ i ] is equal to 2, the i-th image format metadata payload may include bytes from one or more JFIF extended markers excluding the APP0 marker segment identifier itself, as specified in ITU-T Recommendation T.871 | International Standard ISO / IEC 10918-5.

[0158] If ifm_type_id[ i ] is equal to 3, the i-th image format metadata payload may include bytes obtained from the first JFIF marker found after the start of the image, as specified in ITU-T Recommendation T.871 | International Standard ISO / IEC 10918-5.

[0159] If ifm_type_id[ i ] is equal to 4, the i-th image format metadata payload may contain Extensible Metadata Platform (XMP) metadata specified by ISO 16684-1 XML or ISO 16684-3 JSON. Extensible Metadata Platform (XMP) metadata may be specified in ISO 16684-1: Graphic Technology - Extensible metadata platform (XMP) specification or ISO 16684-3: Graphic Technology - Extensible metadata platform (XMP) specification - Part 3 JSON-LD serialization of XMP. XMP is widely used by digital cameras and digital image editing software packages to record provenance and editing history along with the image. The most common set of metadata included in XMP may refer to a vocabulary for storing information such as digital rights ownership and the name of the software package used to modify the image.

[0160] If ifm_type_id[ i ] is equal to 5, the i-th image format metadata payload may contain International Color Consortium (ICC) profile metadata for receivers using a color management workflow described by the ICC. The ICC profile metadata may be specified in ISO 15076-1 or ISO 20677.

[0161] In addition, if ifm_type_id[ i ] is equal to 5, the i-th image format metadata may include a complete ICC profile that complies with the referenced ICC profile standard.

[0162] Additionally, if ifm_type_id[ i ] is equal to 5, ifm_data_payload_byte[ i ][ j ] may be a byte containing data having the syntax and semantics specified in ISO 15076-1 or ISO 20677.

[0163] The variable ICCmajorVer can be set to ifm_data_payload_byte[ i ]

[0008] >> 4 and the variable ICCminorVer can be set to ifm_data_payload_byte[ i ]

[0009] >> 4, and can be interpreted as the major and minor versions of the ICC profile, respectively, as specified in Tables 3 and 4 below.

[0164] ICCmajorVer and ICCminorVer values ​​not listed in Tables 3 and 4 may be reserved for future use by ITU-T | ISO / IEC. These values ​​do not exist in bitstreams conforming to this version of the specification. The decoder ignores image format metadata SEI messages in which these values ​​exist.

[0165] [Table 3]

[0166]

[0167] [Table 4]

[0168]

[0169] Referring again to Table 2, ifm_type_id[ i ], which is the same as 6, can represent the i-th image format metadata payload containing a TIFF revision 6.0 structure compliant with TIFF / EP (ISO 12234-2).

[0170] ifm_uri_present_flag[ i ] can specify whether the i-th image format metadata payload is obtained via a URI having the syntax and semantics specified in IETF Internet Standard 66:

[0171] - ifm_uri_present_flag[ i ], which is the same as 0, may indicate that the image information payload is obtained directly from the payload of the SEI message.

[0172] - Otherwise, ifm_uri_present_flag[ i ], which is identical to 1, may indicate that the image information payload is obtained from the URI.

[0173] ifm_payload_len_minus1[ i ] may represent information related to the length of the i-th video metadata payload (or video format metadata payload). The value of ifm_payload_len_minus1[ i ] plus 1 may represent the length of the i-th video metadata payload. For example, if ifm_type_id[ i ] is equal to 5, the value of ifm_payload_len_minus1[ i ] plus 1 may be 11 or greater.

[0174] ifm_data_payload_byte[ i ][ j ] can specify the j-th byte of the i-th image metadata payload containing data having syntax and semantics specified according to the interpretation of ifm_type_id[ i ] described in Table 2 above.

[0175] ifm_data_uri[ i ] may include a URI having syntax and semantics specified in IETF Internet Standard 66 that identifies an image information payload according to ifm_type_id[ i ] as described in Table 2 above.

[0176] Referring again to the syntax of Table 1, the decoding device (300) parses (or obtains) the ifm_cancel_flag included in the image format metadata SEI message, and if the value of ifm_cancel_flag is false (e.g., 0), parses (or obtains) the ifm_persistence_flag and ifm_num_metadata_payloads. The ifm_persistence_flag can determine whether the current image format metadata SEI message applies only to the current picture, and the number of image format metadata payloads can be derived from ifm_num_metadata_payloads.

[0177] And, a for-loop is executed for each payload (i-th). i starts from 0 and the operation within the for-loop can be repeated up to i that is smaller than ifm_num_metadata_payloads.

[0178] The decoding device (300) can parse (obtain) ifm_type_id[i] to determine what standard the current data is, such as Exif (0), JFIF (1-3), XMP (4), ICC profile (5), etc.

[0179] Additionally, the decoding device (300) can parse (acquire) ifm_uri_present_flag[i] to determine whether the actual data is included in the bitstream or in the external address (URI).

[0180] If ifm_uri_present_flag[i] is false (e.g., 0), the image information (image format metadata) payload can be obtained directly from the payload of the SEI message. Therefore, ifm_payload_len_minus1[i] can be parsed (obtained) and 1 added to it to derive the actual byte length of the payload. Then, to align the exact starting point before reading the actual data, ifm_bit_equal_to_zero (value: 0) can be parsed bit by bit until a byte boundary is reached to fill the space.

[0181] Starting from the aligned position, the actual metadata can be obtained by sequentially reading ifm_data_payload_byte[i][j] byte by byte for the previously verified length.

[0182] Meanwhile, video format metadata SEI messages are included in the VSEI (Versatile Supplemental Information) version 4 messages. Currently, the syntax of video format metadata SEI messages includes ifm_type_id[ i ], which indicates the type of the i-th metadata payload within a loop. Referring to Table 1 mentioned above, ifm_type_id[ i ] is coded as a ue(v) descriptor. That is, ifm_type_id[ i ] has variable length, but there are no constraints on the range of its values ​​specified in the semantics. This can lead to unnecessary memory usage and misinterpretation of SEI messages. For example, since the maximum value of ifm_type_id[ i ] may be implemented differently by system, the interpretation of the same bitstream may vary from system to system. Furthermore, the value range of the data coded as ue(v) needs to be specified to help the decoding system select the appropriate data type for parsing and storing the information conveyed by the corresponding syntax element.

[0183] Additionally, referring to Table 2, some values ​​of ifm_type_id[ i ] (0 to 6) are defined for the current version, while other values ​​(7 to 255) are reserved for future versions. Therefore, it is necessary to define the values ​​allowed for each version and how the decoder handles these values; however, since there is currently no definition on how to handle values ​​not allowed for the current version, this can lead to misinterpretation of SEI messages and problems related to future version expansion.

[0184] In the disclosed embodiment, to solve the above problem, constraints on the range of values ​​of ifm_type_id[ i ] are added to the specifications of the current and future versions, and how the decoder should process those values ​​is defined. The operation of the disclosed embodiment is described in detail below.

[0185] The syntax of Table 1 described above may be applied to the disclosed embodiments. Therefore, the description of the syntax elements included in the image format metadata SEI message described above may be applied in the same way to the disclosed embodiments.

[0186] As described above, ifm_type_id[ i ] can be coded by the descriptor ue(v). ue(v) is an unsigned integer representing a syntax element coded (or encoded) in the zero-order Exp-Golomb encoding method and can be read sequentially starting from the leftmost bit. Additionally, the number of bits used may be variable. The parsing process for ue(v) may be specified such that order k is equal to 0. According to the disclosed embodiment, by imposing constraints on the range of values ​​for the syntax element ifm_type_id[ i ], which represents the type of the image format metadata payload, unnecessary memory usage or misinterpretation of SEI messages can be prevented even if ifm_type_id[ i ] has a variable length. That is, meaningless bit usage can be prevented, and the same interpretation of the heading syntax element can be guaranteed across system implementations.

[0187] For example, the syntax element ifm_type_id[ i ] may be in the range from 0 to 6 (including both ends). Alternatively, you can add a constraint that the value of the syntax element ifm_type_id[ i ] is in the range from 0 to 6 (including both ends). These constraints may be applied to bitstreams that conform to the current version of the specification. That is, in bitstreams that conform to the current version of the specification, the syntax element ifm_type_id[ i ] must be in the range from 0 to 6 (including).

[0188] Additionally, values ​​for ifm_type_id[ i ] from 7 to 255 are reserved for future use by ITU-T | ISO / IEC and must not exist in bitstreams that conform to the current version of the specification. That is, in bitstreams that conform to the current version of the specification, a constraint may be imposed that ifm_type_id[ i ] that falls within the range of 7 to 255 (including both end values) must not exist.

[0189] If ifm_type_id[ i ] has a value in an unallowed range, decoders compliant with the current version of the specification must ignore ifm_type_id[ i ]. In other words, a constraint may be added that decoders compliant with the current version of the specification must ignore ifm_type_id[ i ] if ifm_type_id[ i ] has a value in an unallowed range. For example, if the value of ifm_type_id[ i ] falls within the range of 7 to 255 (including both ends), decoders compliant with the current version of the specification ignore ifm_type_id[ i ].

[0190] Alternatively, if ifm_type_id[ i ] has a value within an unallowed range, decoders compliant with the current version of the specification must ignore the image format metadata SEI message containing ifm_type_id[ i ]. That is, they must ignore all information regarding the i-th image format metadata payload. In other words, if ifm_type_id[ i ] has a value within an unallowed range, a constraint may be added that decoders compliant with the current version of the specification must ignore the image format metadata SEI message containing ifm_type_id[ i ] (or all information regarding the i-th image format metadata payload). For example, if the value of ifm_type_id[ i ] falls within the range of 7 to 255 (including both extreme values), decoders compliant with the current version of the specification ignore the image format metadata SEI message containing ifm_type_id[ i ] (or all information regarding the i-th image format metadata payload).

[0191] According to the disclosed embodiment, by establishing processing rules for values ​​within an unacceptable range, it is possible to prevent the occurrence of problems related to incorrect interpretation of SEI messages or future version extensions.

[0192] The above-described embodiment may be performed by a decoding device (300) and an encoding device (200). For example, the above-described syntax elements and the image format metadata SEI message containing them may be generated by an encoding device (200) according to one embodiment and encoded into image information. The image information encoded in the form of a bitstream may be transmitted to a decoding device (300) according to one embodiment. The decoding device (300) according to one embodiment may obtain image information from the bitstream.

[0193] Hereinafter, a video decoding method performed by a decoding device (300) according to one embodiment and a video encoding method performed by an encoding device (200) will be described in detail.

[0194] FIG. 7 is a diagram illustrating a method for decoding image information according to one embodiment.

[0195] 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.

[0196] 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).

[0197] 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.

[0198] 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.

[0199] Referring to FIG. 7, a method for decoding image information according to one embodiment may include the step of obtaining image information including a message related to image format metadata from a bitstream (S1010), and the step of deriving the type of an image format metadata payload based on information related to a payload type included in the message related to image format metadata (S1020).

[0200] The image format metadata-related message obtained in step S1010 may be the aforementioned image format metadata SEI message. Accordingly, all or part of the description regarding the aforementioned image format metadata SEI message may be applied to the method according to one embodiment. Syntax elements included in the previously described image format metadata SEI message and related variables may be obtained or derived by the method according to one embodiment, and the description regarding the syntax elements included in the previously described image format metadata SEI message and related variables may be applied to the method according to one embodiment without separate mention.

[0201] For example, the syntax of Table 1 described above is applicable to the disclosed embodiment. The payload type information included in the image format metadata SEI message may be the syntax element ifm_type_id[ i ] of Table 1. The payload type information may indicate the type of the corresponding image format metadata payload. For example, ifm_type_id[ i ] may indicate the type of the i-th image format metadata payload. Since the payload type information is coded by the descriptor ue(v), the payload type information has a value greater than or equal to 0.

[0202] The type of image format metadata payload can be defined by a table. For example, as described in Table 2 above, the type of the i-th image format metadata payload can be defined in a table form for each value of ifm_type_id[ i ]. If ifm_type_id[ i ]. is equal to 0, the next image metadata payload may be Exchangeable Image File (Exif) attribute information. If ifm_type_id[ i ]. is equal to 1, 2, or 3, the i-th image format metadata payload may be JFIF metadata specified by ITU-T Recommendation T.871 | ISO / IEC International Standard 10918-5. If ifm_type_id[ i ]. is equal to 4, the i-th image format metadata payload may include Extensible Metadata Platform (XMP) metadata specified by XML of ISO 16684-1 or JSON of ISO 16684-3. If ifm_type_id[ i ] is equal to 5, the i-th image format metadata payload may contain International Color Consortium (ICC) profile metadata for a receiver using a color management workflow described by the ICC. The variable ICCmajorVer may be set to equal to ifm_data_payload_byte[ i ]

[0008] >> 4, and the variable ICCminorVer may be set to equal to ifm_data_payload_byte[ i ]

[0009] >> 4, which can be interpreted as the major and minor versions of the ICC profile, respectively, as specified in Tables 3 and 4 above. ifm_type_id[ i ] equal to 6 may represent the i-th image format metadata payload containing a TIFF revision 6.0 structure compliant with TIFF / EP (ISO 12234-2).

[0203] According to the disclosed embodiment, the value of the payload type related information may be included within a predetermined range. Alternatively, the value of the payload type related information may be limited to within a predetermined range. In other words, the value of the payload type related information may have a constraint that it must be included within a predetermined range. As described above, the payload type related information is coded by the descriptor ue(v) and has a variable length. Therefore, if there is no constraint on the range of the payload type related information, unnecessary memory may be used and the SEI message may be misinterpreted. If the payload type related information has a predetermined range as in the disclosed embodiment, the use of unnecessary memory or misinterpretation of the SEI message can be prevented.

[0204] For example, the value of the payload type information may be included in the range from 0 to 6 (including both ends). Alternatively, the value of the payload type information may be limited to within the range from 0 to 6. In other words, the value of the payload type information may have a constraint that it must be included in the range from 0 to 6.

[0205] According to the disclosed embodiment, if the payload type related information has a value from 0 to 6, the decoding device (300) can determine the type of the image format metadata payload as a type corresponding to the value of the payload type related information. When the type of the image format metadata payload is determined, an appropriate subsequent operation corresponding to the determined type can be performed.

[0206] For example, if the payload type information is equal to 0, the decoding device (300) may determine that the type of the image format metadata payload is Exchangeable Image File (Exif) attribute information. If the payload type information is equal to 1, 2, or 3, the decoding device (300) may determine that the type of the image format metadata payload is JFIF metadata specified by ITU-T Recommendation T.871 | ISO / IEC International Standard 10918-5. If the payload type information is equal to 4, the decoding device (300) may determine that the type of the image format metadata payload is Extensible Metadata Platform (XMP) metadata specified by XML of ISO 16684-1 or JSON of ISO 16684-3. If the payload type information is the same as 5, the decoding device (300) can determine that the type of the image format metadata payload is International Color Consortium (ICC) profile metadata for a receiver using a color management workflow described by the ICC.

[0207] According to the disclosed embodiment, values ​​outside the aforementioned allowable range (from 0 to 6), i.e., the range from 7 to 255 (including both ends), may be reserved for use in future versions. For example, values ​​within the range from 7 to 255 (including both ends) may be reserved for future use by ITU-T | ISO / IEC. Accordingly, in a bitstream conforming to the specifications of the current version according to the disclosed embodiment, values ​​within the range from 7 to 255 (including both ends) may be restricted from existing for payload type related information. That is, restrictions may be placed so that payload type related information having a range from 7 to 255 (including both ends) does not exist.

[0208] Despite these constraints, if the value of the payload type related information included in the video format metadata SEI message acquired by the decoding device (300) does not fall within the aforementioned allowable range (0 to 6), that is, if it falls within the range from 7 to 255 (including both end values), the decoding device (300) may ignore information regarding the video format metadata payload corresponding to the payload type related information. For example, if the value of ifm_type_id[i] falls within the range from 7 to 255 (including both end values), the decoding device (300) may ignore information regarding the i-th video format metadata payload.

[0209] In this case, it is possible to ignore all information regarding the i-th video format metadata payload, or to ignore only some information. For example, if only some information is ignored, information related to the payload type, namely ifm_type_id[i], can be ignored.

[0210] Alternatively, if the value of the payload type related information included in the video format metadata SEI message acquired by the decoding device (300) falls within the range from 7 to 255 (including both end values), the decoding device (300) may ignore the SEI message corresponding to the payload type related information. For example, if the value of ifm_type_id[i] falls within the range from 7 to 255 (including both end values), the decoding device (300) may ignore the information regarding the i-th video format metadata payload in the video format metadata SEI message.

[0211] In this way, by imposing constraints on the range of values ​​for the syntax element ifm_type_id[ i ], which indicates the type of the image format metadata payload, unnecessary memory usage or misinterpretation of SEI messages can be prevented even if ifm_type_id[ i ] has variable length. Additionally, by establishing rules for handling values ​​within an unallowed range, misinterpretation of SEI messages or problems related to future version expansion can be prevented.

[0212] FIG. 8 is a diagram illustrating a method for encoding image information according to one embodiment.

[0213] 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.

[0214] 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).

[0215] 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.

[0216] 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.

[0217] Referring to FIG. 8, a method for encoding image information according to one embodiment may include the step of generating payload type related information based on the type of image metadata payload (S1110), the step of generating an image format metadata related message including the payload type related information (S1120), and the step of encoding image information including the image format metadata related message (S1130).

[0218] The image format metadata-related message generated in step S1120 may be the aforementioned image format metadata SEI message. Accordingly, all or part of the description regarding the aforementioned image format metadata message may be applied to the method according to one embodiment. Syntax elements included in the previously described image format metadata SEI message and related variables may be generated or derived by the method according to one embodiment, and the description regarding the syntax elements included in the previously described image format metadata SEI message and related variables may be applied to the method according to one embodiment without separate mention.

[0219] When image information is encoded in the form of a bitstream by a method according to one embodiment, this bitstream can be transmitted to a decoding device by a transmission unit or a transmission device. That is, the syntax elements used in the method described above based on FIG. 7 can be generated by the method according to the embodiment. In addition, as described above, the encoding device (200) and the decoding device (300) can perform corresponding operations. Therefore, all or part of the content described above with reference to FIG. 7 can also be applied to the image encoding method according to the embodiment.

[0220] For example, the syntax of Table 1 described above is applicable to the disclosed embodiment. The payload type information included in the image format metadata SEI message may be the syntax element ifm_type_id[ i ] of Table 1. The payload type information may indicate the type of the corresponding image format metadata payload. For example, ifm_type_id[ i ] may indicate the type of the i-th image format metadata payload. Since the payload type information is coded by the descriptor ue(v), the payload type information has a value greater than or equal to 0.

[0221] The type of image format metadata payload can be defined by a table. For example, as described in Table 2 above, the type of the i-th image format metadata payload can be defined in a table form for each value of ifm_type_id[ i ]. If ifm_type_id[ i ]. is equal to 0, the next image metadata payload may be Exchangeable Image File (Exif) attribute information. If ifm_type_id[ i ]. is equal to 1, 2, or 3, the i-th image format metadata payload may be JFIF metadata specified by ITU-T Recommendation T.871 | ISO / IEC International Standard 10918-5. If ifm_type_id[ i ]. is equal to 4, the i-th image format metadata payload may include Extensible Metadata Platform (XMP) metadata specified by XML of ISO 16684-1 or JSON of ISO 16684-3. If ifm_type_id[ i ] is equal to 5, the i-th image format metadata payload may contain International Color Consortium (ICC) profile metadata for a receiver using a color management workflow described by the ICC. The variable ICCmajorVer may be set to equal to ifm_data_payload_byte[ i ]

[0008] >> 4, and the variable ICCminorVer may be set to equal to ifm_data_payload_byte[ i ]

[0009] >> 4, which can be interpreted as the major and minor versions of the ICC profile, respectively, as specified in Tables 3 and 4 above. ifm_type_id[ i ] equal to 6 may represent the i-th image format metadata payload containing a TIFF revision 6.0 structure compliant with TIFF / EP (ISO 12234-2).

[0222] The encoding device (200) can generate payload type related information (ifm_type_id[i]) as described above, based on the type of the corresponding video format metadata payload.

[0223] According to the disclosed embodiment, the value of the payload type related information generated by the encoding device (200) may be included within a predetermined range. Alternatively, the value of the payload type related information may be limited to within a predetermined range. In other words, the value of the payload type related information may have a constraint that it must be included within a predetermined range. As described above, the payload type related information is coded by the descriptor ue(v) and has a variable length. Therefore, if there is no constraint on the range of the payload type related information, unnecessary memory may be used and the SEI message may be misinterpreted. If the payload type related information has a predetermined range as in the disclosed embodiment, the use of unnecessary memory or misinterpretation of the SEI message can be prevented.

[0224] For example, the value of the payload type related information may be included in the range from 0 to 6 (including both end values). Alternatively, the value of the payload type related information may be limited to within the range from 0 to 6. In other words, the value of the payload type related information may have a constraint that it must be included in the range from 0 to 6. The encoding device (200) can generate payload type related information that meets these constraints. That is, the encoding device (200) can generate payload type related information that is included in the range from 0 to 6.

[0225] For example, if the type of the image format metadata payload is Exchangeable Image File (Exif) attribute information, the encoding device (200) can generate payload type related information identical to 0. If the type of the image format metadata payload is JFIF metadata specified by ITU-T Recommendation T.871 | ISO / IEC International Standard 10918-5, the encoding device (200) can generate payload type related information identical to 1, 2, or 3. If the type of the image format metadata payload is Extensible Metadata Platform (XMP) metadata specified by XML of ISO 16684-1 or JSON of ISO 16684-3, the encoding device (200) can generate payload type related information identical to 4. If the type of the image format metadata payload is International Color Consortium (ICC) profile metadata for a receiver using a color management workflow described by the ICC, the encoding device (200) can generate payload type related information identical to 5.

[0226] According to the disclosed embodiment, values ​​outside the aforementioned allowable range (from 0 to 6), i.e., the range from 7 to 255 (including both ends), may be reserved for use in future versions. For example, values ​​within the range from 7 to 255 (including both ends) may be reserved for future use by ITU-T | ISO / IEC. Accordingly, in a bitstream conforming to the specifications of the current version according to the disclosed embodiment, values ​​within the range from 7 to 255 (including both ends) may be restricted from existing for payload type related information. That is, restrictions may be imposed so that payload type related information having a range from 7 to 255 (including both ends) does not exist.

[0227] Despite these constraints, if the value of the payload type information included in the video format metadata SEI message generated by the encoding device (200) does not fall within the aforementioned allowable range (0 to 6), that is, if it falls within the range from 7 to 255 (including both end values), the information regarding the video format metadata payload corresponding to the payload type information may be ignored by the decoding device (300) that received the bitstream. For example, if the value of ifm_type_id[i] falls within the range from 7 to 255 (including both end values), the information regarding the i-th video format metadata payload may be ignored by the decoding device (300).

[0228] In this case, it is possible to ignore all information regarding the i-th video format metadata payload, or to ignore only some information. For example, if only some information is ignored, information related to the payload type, namely ifm_type_id[i], may be ignored.

[0229] Alternatively, if the value of the payload type related information included in the video format metadata SEI message generated by the encoding device (200) falls within the range from 7 to 255 (including both end values), the SEI message corresponding to the payload type related information may be ignored by the decoding device (300) that receives the bitstream. For example, if the value of ifm_type_id[i] falls within the range from 7 to 255 (including both end values), the information regarding the i-th video format metadata payload in the video format metadata SEI message may be ignored by the decoding device (300).

[0230] In this way, by imposing constraints on the range of values ​​for the syntax element ifm_type_id[ i ], which indicates the type of the image format metadata payload, unnecessary memory usage or misinterpretation of SEI messages can be prevented even if ifm_type_id[ i ] has variable length. Additionally, by establishing rules for handling values ​​within an unallowed range, misinterpretation of SEI messages or problems related to future version expansion can be prevented.

[0231] When video information is encoded according to the method described above, a bitstream can be generated, and the generated bitstream can be stored non-transiently on a computer-readable storage medium.

[0232] 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 method (a method for encoding image information). A method for transmitting a bitstream according to one embodiment may be performed by a transmission device, and the transmission device may include at least one processor for generating a bitstream and at least one memory for transmitting the generated bitstream. At least one processor and at least one memory may be electrically connected.

[0233] FIG. 9 is a drawing illustrating an exemplary content streaming system to which an embodiment according to the present disclosure can be applied.

[0234] As illustrated in FIG. 9, 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.

[0235] 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.

[0236] 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.

[0237] 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.

[0238] 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.

[0239] 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.

[0240] 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.

[0241] 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.

[0242] An embodiment according to the present disclosure can be used to encode / decode images.

Claims

1. A step of obtaining image information including a message related to image format metadata from a bitstream; and The method includes the step of deriving the type of the image format metadata payload based on information related to the payload type included in the message related to the image format metadata above; A method in which the value of the above payload type related information is included in the range from 0 to 6.

2. In Paragraph 1, The method, wherein the payload type information having a value from 7 to 255 does not exist in the bitstream.

3. In Paragraph 1, A method having a constraint that the value of the above payload type related information must be included in the range from 0 to 6.

4. In Paragraph 1, A method in which information regarding an image format metadata payload corresponding to the payload type information is ignored based on the fact that the value of the above payload type information is included in the range from 7 to 255.

5. In Paragraph 1, A method in which the payload type-related information is ignored based on the fact that the value of the payload type-related information is included in the range from 7 to 255.

6. A step of generating payload type-related information based on the type of the video metadata payload; A step of generating a message related to image format metadata including information related to the above-mentioned payload type; and The method includes the step of encoding video information containing a message related to the video format metadata into a bitstream; and A method in which the value of the above payload type related information is included in the range from 0 to 6.

7. In Paragraph 6, In paragraph 1, The method, wherein the payload type information having a value from 7 to 255 does not exist in the bitstream.

8. In Paragraph 6, A method having a constraint that the value of the above payload type related information must be included in the range from 0 to 6.

9. A computer-readable storage medium that non-transiently stores a bitstream generated by the method of claim 6 above.

10. 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 payload type-related information based on the type of video metadata payload; A step of generating a message related to image format metadata including information related to the above-mentioned payload type; and The method includes the step of encoding image information including a message related to the image format metadata above; and A method in which the value of the above payload type related information is included in the range from 0 to 6.

Images