Method for decoding image information, method for encoding image information, and method for transmitting data for image information

Abstract

A method for decoding image information, according to the present disclosure, comprises: acquiring image information including supplemental enhancement information (SEI) messages, an SEI processing order message indicating a processing order for a group of types of the SEI messages, and a processing order nested message including at least one nested SEI message in a processing chain designated by the SEI processing order message; and deriving the processing order for the group of types of the SEI messages on the basis of the SEI processing order message, wherein the SEI processing order message can include wrapping flag information indicating whether an SEI message in the processing chain designated by the SEI processing order message is included in or excluded from the processing order nested message.

Description

A method for decoding image information, a method for encoding image information, and a method for transmitting data regarding image information.

[0001] The present disclosure relates to a method for decoding image information, a method for encoding image information, and / or a method for transmitting data relating to image information.

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

[0003] Accordingly, a highly efficient image compression technology is required to effectively transmit, store, and play high-resolution, high-quality image information.

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

[0005] The present disclosure seeks to provide flexibility to the Supplemental Enhancement Information (SEI) message.

[0006] The present disclosure seeks to provide an encoding / decoding method and / or device with improved coding efficiency and coding speed by the flexibility of SEI messages.

[0007] The technical problems to be achieved in the present disclosure are not limited to the technical problems mentioned above, and other technical problems not mentioned can be clearly understood by a person having ordinary skill in the technical field to which the present disclosure belongs from the description below.

[0008] According to one aspect of the present disclosure, a method of decoding video information may include obtaining video information including supplemental enhancement information (SEI) messages, an SEI processing order message indicating a processing order for a group of types of the SEI messages, and a processing order nesting message including at least one nested SEI message within a processing chain designated by the SEI processing order message, and deriving a processing order for the group of types of the SEI messages based on the SEI processing order message. The SEI processing order message may include wrapping flag information indicating whether an SEI message within the processing chain designated by the SEI processing order message is included in the processing order nesting message or not.

[0009] According to one aspect of the present disclosure, a device for decoding video information includes a memory and a processor connected to the memory, wherein the processor obtains video information including supplemental enhancement information (SEI) messages, an SEI processing order message indicating a processing order for a group of types of the SEI messages, and a processing order nesting message including at least one nested SEI message within a processing chain designated by the SEI processing order message, and can derive a processing order for the group of types of the SEI messages based on the SEI processing order message. The SEI processing order message can include wrapping flag information indicating whether an SEI message within the processing chain designated by the SEI processing order message is included in the processing order nesting message or not.

[0010] In the method or device for decoding the image information, based on the value of the wrapping flag information being 1, an SEI message within a processing chain specified by the SEI processing order message may be included in the processing order overlap message, and based on the value of the wrapping flag information being 0, an SEI message within a processing chain specified by the SEI processing order message may not be included in the processing order overlap message.

[0011] In the method or device for decoding the image information, based on the value of the wrapping flag information being 1, target identification information of the processing order nested message is the same as identification information of the SEI processing order message, a payload type of the at least one nested SEI message is the same as a payload type specified by the SEI processing order message, and a processing order of the at least one nested SEI message may be the same as a processing order specified by the SEI processing order message.

[0012] In the method or device for decoding the above image information, it may be permissible for an SEI message within a processing chain specified by the SEI processing order message not to exist in the image information.

[0013] In the method or device for decoding the above image information, the SEI message in the processing chain specified by the SEI processing order message may include at least one of an SEI message present in the image information or an SEI message not present in the image information.

[0014] In the method or device for decoding the above image information, the SEI processing order message includes payload type information indicating the type of the SEI message, and the payload type information may include at least one of type information of an SEI message present in the image information or type information of an SEI message not present in the image information.

[0015] In the method or device for decoding the image information, based on the fact that the value of the wrapping flag information is 1 and an SEI message within a processing chain specified by the SEI processing order message exists in the image information, the SEI message within the processing chain may be included in the processing order overlapping message, and based on the fact that the value of the wrapping flag information is 0 and an SEI message within the processing chain specified by the SEI processing order message exists in the image information, the SEI message within the processing chain may not be included in the processing order overlapping message.

[0016] According to one aspect of the present disclosure, a method for encoding video information may include generating a supplemental enhancement information (SEI) message, determining a processing order for a group of types of the SEI messages, generating an SEI processing order message indicating the processing order based on the processing order, generating a processing order nested message including at least one nested SEI message within a processing chain specified by the SEI processing order message, and encoding video information including the SEI processing order message and the processing order nested message. The SEI processing order message may include wrapping flag information indicating whether an SEI message within the processing chain specified by the SEI processing order message is included in the processing order nested message or not.

[0017] According to one aspect of the present disclosure, a device for encoding video information includes a memory and a processor connected to the memory, wherein the processor generates a supplemental enhancement information (SEI) message, determines a processing order for a group of types of the SEI messages, generates an SEI processing order message indicating the processing order based on the processing order, generates a processing order nested message including at least one nested SEI message within a processing chain designated by the SEI processing order message, and encodes video information including the SEI processing order message and the processing order nested message. The SEI processing order message may include wrapping flag information indicating whether an SEI message within the processing chain designated by the SEI processing order message is included in the processing order nested message or not.

[0018] In the method or device for encoding the image information, the value of the wrapping flag information may be 1 based on the SEI message within the processing chain specified by the SEI processing order message being included in the processing order overlapping message, and the value of the wrapping flag information may be 0 based on the SEI message within the processing chain specified by the SEI processing order message not being included in the processing order overlapping message.

[0019] In the method or device for decoding the image information, based on the value of the wrapping flag information being 1, target identification information of the processing order nested message is the same as identification information of the SEI processing order message, a payload type of the at least one nested SEI message is the same as a payload type specified by the SEI processing order message, and a processing order of the at least one nested SEI message may be the same as a processing order specified by the SEI processing order message.

[0020] In the method or device for decoding the above image information, it may be permissible for an SEI message within a processing chain specified by the SEI processing order message not to exist in the image information.

[0021] In the method or device for decoding the above image information, the SEI message in the processing chain specified by the SEI processing order message may include at least one of an SEI message present in the image information or an SEI message not present in the image information.

[0022] In the method or device for decoding the above image information, the SEI processing order message includes payload type information indicating the type of the SEI message, and the payload type information may include at least one of type information of an SEI message present in the image information or type information of an SEI message not present in the image information.

[0023] In the method or device for decoding the image information, based on the fact that the value of the wrapping flag information is 1 and an SEI message within a processing chain specified by the SEI processing order message exists in the image information, the SEI message within the processing chain can be included in the processing order overlapping message, and based on the fact that the value of the wrapping flag information is 0 and an SEI message within the processing chain specified by the SEI processing order message exists in the image information, the SEI message within the processing chain can be indicated as not being included in the processing order overlapping message.

[0024] According to one aspect of the present disclosure, a method for transmitting data regarding video information may include generating a bitstream regarding the video information and transmitting data including the bitstream. The bitstream may be generated based on generating a supplemental enhancement information (SEI) message, determining a processing order for a group of types of the SEI messages, generating an SEI processing order message indicating the processing order based on the processing order and a processing order nested message including at least one nested SEI message within a processing chain designated by the SEI processing order message, and generating a bistream including video information including the SEI processing order message and the processing order nested message. The SEI processing order message may include wrapping flag information indicating whether an SEI message within a processing chain designated by the SEI processing order message is included in the processing order nested message or not.

[0025] According to one aspect of the present disclosure, a device for transmitting data regarding image information may include a processor for generating a bitstream regarding the image information and a data transmitting unit for transmitting data including the bitstream. The bitstream may be generated based on generating an SEI (supplemental enhancement information) message, determining a processing order for a group of types of the SEI messages, generating an SEI processing order message indicating the processing order based on the processing order and a processing order superposition message including at least one superposed SEI message within a processing chain designated by the SEI processing order message, and generating a bistream including image information including the SEI processing order message and the processing order superposition message. The SEI processing order message may include wrapping flag information for indicating whether an SEI message within the processing chain designated by the SEI processing order message is included in the processing order superposition message or not.

[0026] According to one aspect of the present disclosure, a computer-readable storage medium may store a bitstream relating to image information. The bitstream may be generated based on generating a supplemental enhancement information (SEI) message, determining a processing order for a group of types of the SEI messages, generating an SEI processing order message indicating the processing order based on the processing order and a processing order nested message including at least one nested SEI message within a processing chain designated by the SEI processing order message, and generating a bistream including image information including the SEI processing order message and the processing order nested message. The SEI processing order message may include wrapping flag information indicating whether an SEI message within the processing chain designated by the SEI processing order message is included in the processing order nested message or not.

[0027] 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.

[0028] According to the present disclosure, an encoding / decoding method and / or device with improved coding efficiency can be provided.

[0029] According to the present disclosure, flexibility can be provided to the Supplemental Enhancement Information (SEI) message.

[0030] According to the present disclosure, an encoding / decoding method and / or device can be provided that improves coding efficiency and coding speed by the flexibility of SEI messages.

[0031] The effects that can be obtained from the present disclosure are not limited to the effects mentioned above, and other effects that are not mentioned will be clearly understood by a person having ordinary skill in the art to which the present disclosure pertains from the description below.

[0032] FIG. 1 is a diagram schematically illustrating a video coding system to which an embodiment according to the present disclosure can be applied.

[0033] FIG. 2 is a schematic diagram of an encoding device to which an embodiment according to the present disclosure can be applied.

[0034] FIG. 3 is a schematic diagram illustrating a decoding device to which an embodiment according to the present disclosure can be applied.

[0035] Figure 4 illustrates an example of a hierarchical structure for coded video / images.

[0036] FIG. 5 is a diagram illustrating a method for decoding image information according to one embodiment of the present disclosure.

[0037] FIG. 6 is a diagram illustrating a method for encoding image information according to one embodiment of the present disclosure.

[0038] FIG. 7 is a diagram exemplarily showing a content streaming system to which an embodiment according to the present disclosure can be applied.

[0039] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the attached drawings so that those skilled in the art can easily implement the present disclosure. However, the present disclosure may be implemented in various different forms and is not limited to the embodiments described herein.

[0040] In describing embodiments of the present disclosure, detailed descriptions of known configurations or functions will be omitted if they are deemed to obscure the gist of the present disclosure. Furthermore, portions unrelated to the description of the present disclosure in the drawings have been omitted, and similar portions have been designated with similar reference numerals.

[0041] In the present disclosure, when a component is said to be "connected," "coupled," or "connected" to 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 said to "include" or "have" another component, unless otherwise specifically stated, this does not exclude the other component, but rather implies that the other component may be included.

[0042] In this disclosure, terms such as first, second, etc. are used solely to distinguish one component from another, and do not limit the order or importance of components unless specifically stated otherwise. Accordingly, within the scope of this disclosure, a first component in one embodiment may be referred to as a second component in another embodiment, and similarly, a second component in one embodiment may be referred to as a first component in another embodiment.

[0043] In this disclosure, distinct components are used to clearly illustrate their respective characteristics, and do not necessarily imply that the components are separated. That is, multiple components may be integrated into a single hardware or software unit, or a single component may be distributed into multiple hardware or software units. Therefore, even if not specifically mentioned, such integrated or distributed embodiments are also included within the scope of this disclosure.

[0044] In the present disclosure, the components described in various embodiments are not necessarily essential components, and some may be optional components. Therefore, embodiments comprising a subset of the components described in one embodiment are also within the scope of the present disclosure. Furthermore, embodiments including other components in addition to the components described in various embodiments are also within the scope of the present disclosure.

[0045] The present disclosure relates to encoding and decoding of video. For example, the methods and embodiments disclosed in this document can be applied to methods disclosed in the versatile video coding (VVC) standard, the essential video coding (EVC) standard, the AOMedia Video 1 (AV1) standard, the second generation of audio video coding standard (AVS2), or the next generation of video / image coding standards (e.g., H.267 or H.268).

[0046] The present disclosure presents various embodiments of video / image coding, and unless otherwise stated, the embodiments may be performed in combination with each other.

[0047] Terms used in this disclosure may have their usual meanings commonly used in the technical field to which this disclosure belongs, unless newly defined in this disclosure.

[0048] In this disclosure, "video" may mean a set of images over time. In this disclosure, "picture" generally means a unit representing one image at a specific time point, and a slice / tile is a unit that constitutes a part of a picture in coding. A slice / tile may include one or more CTUs (coding tree units). 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 ​​CTU rows within a tile in a picture. In this document, tile group and slice may be used interchangeably. For example, in this document, a tile group / tile group header may be referred to as a slice / slice header.

[0049] In the present disclosure, "pixel" or "pel" may refer to the smallest unit that constitutes a picture (or image). Additionally, "sample" may be used as a term corresponding to a pixel. A sample may generally represent a pixel or a pixel value, and may represent only a pixel / pixel value of a luma component or only a pixel / pixel value of a chroma component.

[0050] In the present disclosure, a "unit" may represent a basic unit of image processing. A unit may include at least one of a specific region of a picture and information related to the region. One unit may include one luma block and two chroma (e.g., cb, cr) blocks. In some cases, the term "unit" may be used interchangeably with terms such as "block" or "area." In general, an MxN block may include a set (or array) of samples (or sample array) or transform coefficients consisting of M columns and N rows.

[0051] In the present disclosure, the "current block" may mean one of the following: a "current coding block," a "current coding unit," a "block to be encoded," a "block to be decoded," or a "block to be processed." When prediction is performed, the "current block" may mean a "current prediction block" or a "block to be predicted." When transformation (inverse transformation) / quantization (inverse quantization) is performed, the "current block" may mean a "current transformation block" or a "block to be transformed." When filtering is performed, the "current block" may mean a "block to be filtered."

[0052] In the present disclosure, a "current block" may mean a block that includes both a luma component block and a chroma component block, or a "luma block of the current block," unless explicitly described as a chroma block. The luma component block of the current block may be explicitly expressed by including an explicit description of the luma component block, such as "luma block" or "current luma block." Additionally, the chroma component block of the current block may be explicitly expressed by including an explicit description of the chroma component block, such as "chroma block" or "current chroma block."

[0053] In this disclosure, " / " and "," can be interpreted as "and / or". For example, "A / B" and "A, B" can be interpreted as "A and / or B". Additionally, "A / B / C" and "A, B, C" can mean "at least one of A, B, and / or C."

[0054] In this 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, "or" in this disclosure may mean "additionally or alternatively."

[0055] FIG. 1 is a schematic diagram illustrating a video / image coding system to which an embodiment according to the present disclosure can be applied.

[0056] 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 to the receiving device via a digital storage medium or a network in the form of a file or streaming.

[0057] The source device may include a video source, an encoding device, and a transmitter. The receiving device may include a receiver, a decoding device, and a renderer. The encoding device may be referred to as a video / video encoding device, and the decoding device may be referred to as a video / video 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 configured as a separate device or an external component.

[0058] A video source may obtain video / images through a process of capturing, synthesizing, or generating video / images. The video source may include a video / image capture device and / or a video / image generation device. A video / image capture device may include, for example, one or more cameras, a video / image archive containing previously captured video / images, etc. A video / image generation device may include, for example, a computer, a tablet, a smartphone, etc., and may (electronically) generate video / images. For example, a virtual video / image may be generated through a computer, etc., in which case the video / image capture process may be replaced by a process of generating related data.

[0059] An encoding device can encode input video / images. The encoding device can perform a series of procedures, such as prediction, transformation, and quantization, to improve compression and coding efficiency. The encoded data (encoded video / image information) can be output in the form of a bitstream.

[0060] 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 network in the form of a file or streaming. The digital storage medium can include various storage media such as USB, SD, CD, DVD, Blu-ray, HDD, SSD, etc. The transmission unit can include an element for generating a media file via a predetermined file format and an element for transmission via a broadcasting / communication network. The receiving unit can receive / extract the bitstream and transmit it to a decoding device.

[0061] The decoding device can decode the video / image by performing a series of procedures such as inverse quantization, inverse transformation, and prediction corresponding to the operation of the encoding device.

[0062] The renderer can render decoded video / images. The rendered video / images can be displayed through the display unit.

[0063] FIG. 2 is a schematic diagram illustrating an encoding device to which an embodiment according to the present disclosure can be applied.

[0064] Referring to FIG. 2, the encoding device (200) may be configured to include an image partitioner (210), a prediction unit (predictor) 220, a residual processor (residual processor) 230, an entropy encoder (entropy encoder) 240, an adder (adder) 250, a filter (filter) 260, and a memory (memory) 270. The prediction unit (220) may include an inter prediction unit (221) and an intra prediction unit (222). The residual processor (230) may include a transformer (transformer) 232, a quantizer (quantizer) 233, a dequantizer (dequantizer) 234, and an inverse transformer (inverse transformer) 235. The residual processing unit (230) may further include a subtractor (231). The addition unit (250) may be called a reconstructor or a recontructed block generator. The image segmentation unit (210), the prediction unit (220), the residual processing unit (230), the entropy encoding unit (240), the addition unit (250), and the filtering unit (260) described above may be configured by one or more hardware components (e.g., an encoder chipset or a processor) depending on the embodiment. In addition, the memory (270) may include a DPB (Decoded Picture Buffer) and may be configured by a digital storage medium. The hardware component may further include the memory (270) as an internal / external component.

[0065] The image segmentation unit (210) can segment an input image (or picture, frame) input to the encoding device (200) into one or more processing units. For example, the processing units may be referred to as coding units (CUs). A coding unit may be recursively segmented 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, one coding unit may be segmented into a plurality of coding units of deeper depth based on a quad-tree structure, a binary tree structure, and / or a ternary tree structure. For example, the quad-tree structure may be applied first, and the binary tree structure and / or the ternary tree structure may be applied later. Alternatively, the binary tree structure may be applied first. A coding procedure according to the present disclosure may be performed based on a final coding unit that is no longer segmented. In this case, based on coding efficiency according to image characteristics, etc., the maximum coding unit may be used as the final coding unit, or, if necessary, the maximum coding unit may be recursively divided into coding units of lower depths, and the coding unit of the optimal size may be used as the final coding unit. Here, the coding procedure may include procedures such as prediction, transformation, and restoration, which will be 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 for deriving a transformation coefficient and / or a unit for deriving a residual signal from a transformation coefficient.

[0066] The term "unit" may be used interchangeably with terms such as "block" or "area" depending on the case. In general, an MxN block can 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 can represent only the pixel / pixel value of the luminance component, or only the pixel / pixel value of the chroma component. A sample can be used as a term corresponding to a pixel or pel in a picture (or image).

[0067] 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 video signal (original block, original sample array), and the generated residual signal is transmitted to a conversion unit (232). In this case, as illustrated, a unit that subtracts a prediction signal (prediction block, prediction sample array) from an input video signal (original block, original sample array) within the encoding device (200) may be called a subtraction unit (231). The prediction unit (220) can perform prediction on a block to be processed (hereinafter, current block) and generate a predicted block including prediction samples for the current block. The prediction unit (220) can determine whether intra prediction or inter prediction is applied on a current block or CU basis. The prediction unit (220) can generate various information regarding prediction, such as prediction mode information, as described later in the description of each prediction mode, and transmit the information 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.

[0068] The intra prediction unit (222) can predict the current block by referring to samples within the current picture. The referenced samples may be located in the neighborhood of the current block or may be located away from it depending on the prediction mode. In intra prediction, the prediction modes may include multiple non-directional modes and multiple 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 detail in the prediction direction. However, this is merely an example, and a greater or lesser number of directional prediction modes may be used depending on the settings. The intra prediction unit (222) may also determine the prediction mode applied to the current block by using the prediction mode applied to the neighboring blocks.

[0069] 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, in order to reduce the amount of motion information transmitted in the inter prediction mode, the motion information can be predicted in units of blocks, subblocks, or samples based on the correlation of the motion information between the neighboring blocks and the current block. The motion information can include a motion vector and a reference picture index. The motion information can further include information on the inter prediction direction (L0 prediction, L1 prediction, Bi prediction, etc.). In the case of inter prediction, the neighboring block can include a spatial neighboring block existing in the current picture and a temporal neighboring block existing in the reference picture. The reference picture including the reference block and the reference picture including the temporal neighboring block may be the same or different from each other. The temporal neighboring block may be called a collocated reference block, a collocated CU (colCU), etc. A reference picture including the above temporal neighboring blocks may be called a collocated picture (colPic). For example, the inter prediction unit (221) may construct a motion information candidate list based on neighboring 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, and for example, in the case of skip mode and merge mode, the inter prediction unit (221) may use the motion information of neighboring blocks as the motion information of the current block. In the case of skip mode, unlike the merge mode, a residual signal may not be transmitted.In the motion vector prediction (MVP) mode, the motion vector of the 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.

[0070] The prediction unit (220) can generate a prediction signal based on various prediction methods and / or prediction techniques described below. For example, the prediction unit (220) can apply intra prediction or inter prediction to predict the current block, and can also apply intra prediction and inter prediction simultaneously. A prediction method that simultaneously applies intra prediction and inter prediction to predict the current block may be called combined inter and intra prediction (CIIP). In addition, the prediction unit (220) 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 image / video coding such as games, such as screen content coding (SCC). IBC basically performs prediction within the current picture, but can be performed similarly to inter prediction in that it derives a reference block within the current picture. That is, IBC may utilize at least one of the inter prediction techniques described in this document. Palette mode can be viewed as an example of intracoding or intraprediction. When applied, palette mode can signal sample values ​​within a picture based on information about the palette table and palette index.

[0071] The prediction signal generated through the prediction unit (220) can be used to generate a restoration signal or a residual signal. The subtraction unit (231) can generate a residual signal (residual block, residual sample array) by subtracting the prediction signal (predicted block, predicted 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).

[0072] The transform unit (232) can apply a transform technique to the residual signal to generate transform coefficients. For example, the transform technique can 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 transform obtained from a graph when the relationship information between pixels is expressed as a graph. CNT refers to a transform obtained based on generating a prediction signal using all previously reconstructed pixels. The transform process can be applied to a pixel block having a square equal size, or can be applied to a block of a non-square variable size.

[0073] The quantization unit (233) can quantize the transform coefficients and transmit them to the entropy encoding unit (240). The entropy encoding unit (240) can encode the quantized signal (information about the quantized transform coefficients) and output it as a bitstream. The information about the quantized transform coefficients can be called residual information. The quantization unit (233) can rearrange the quantized transform coefficients in a block form into a one-dimensional vector form based on the coefficient scan order, and can also generate information about the quantized transform coefficients based on the quantized transform coefficients in the one-dimensional vector form.

[0074] The entropy encoding unit (240) can perform various encoding methods such as, for example, exponential Golomb, context-adaptive variable length coding (CAVLC), context-adaptive binary arithmetic coding (CABAC), etc. The entropy encoding unit (190) can also encode, together or separately, information necessary for video / image restoration (e.g., values ​​of syntax elements, etc.) in addition to quantized transform coefficients. The encoded information (e.g., encoded video / image information) can be transmitted or stored in the form of a bitstream in the form of a network abstraction layer (NAL) unit. The video / image information may further include information on 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). In addition, the video / image information may further include general constraint information. The signaled information, transmitted information, and / or syntax elements mentioned in the present disclosure may be included in video / image information. The video / image information may be encoded through the encoding procedure described above and included in the bitstream.

[0075] 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 the signal output from the entropy encoding unit (240) and / or a storage unit (not shown) for storing the signal 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).

[0076] The quantized transform coefficients output from the quantization unit (233) can be used to generate a residual signal. For example, by applying inverse quantization and inverse transformation to the quantized transform coefficients through the inverse quantization unit (234) and inverse transformation unit (235), a residual signal (residual block or residual samples) can be restored.

[0077] Meanwhile, LMCS (luma mapping with chroma scaling) may be applied during the picture encoding and / or restoration process.

[0078] The addition unit (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). When there is no residual for the block to be processed, such as when skip mode is applied, the predicted block can be used as the reconstructed block. The addition unit (250) can 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 filtering as described below.

[0079] The filtering unit (260) can improve subjective / objective picture quality by applying filtering to the restoration signal. For example, the filtering unit (260) can apply various filtering methods to the restoration picture to generate a modified restoration picture, and store the modified restoration picture in the memory (270), specifically, the DPB of the memory (170). The various filtering methods may include, for example, deblocking filtering, sample adaptive offset, adaptive loop filter, bilateral filter, etc. The filtering unit (260) can generate various information regarding filtering and transmit it to the entropy encoding unit (240), as described later in the description of each filtering method. The information regarding filtering can be encoded by the entropy encoding unit (240) and output in the form of a bitstream.

[0080] The modified restored picture transmitted to the memory (270) can be used as a reference picture in the inter prediction unit (221). Through this, when inter prediction is applied, the encoding device (200) can avoid prediction mismatch between the encoding device (200) and the decoding device, and can also improve encoding efficiency.

[0081] The DPB in the memory (270) can store a modified reconstructed picture to be used as a reference picture in the inter prediction unit (221). The memory (270) can store motion information of a block from which motion information in the current picture is derived (or encoded) and / or motion information of blocks in a picture that has already been reconstructed. The stored motion information can be transferred to the inter prediction unit (221) to be used as motion information of a spatial neighboring block or motion information of a temporal neighboring block. The memory (270) can store reconstructed samples of reconstructed blocks in the current picture and transfer them to the intra prediction unit (222).

[0082] FIG. 3 is a schematic diagram illustrating a decoding device to which an embodiment according to the present disclosure can be applied.

[0083] 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-prediction unit (332) and an intra-prediction unit (331). The residual processor (320) may include a dequantizer (321) and an inverse transformer (321). The entropy decoding unit (310), residual processing unit (320), prediction unit (330), addition unit (340), and filtering unit (350) described above may be configured by a single hardware component (e.g., decoder chipset or processor) depending on the embodiment. In addition, 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.

[0084] When a bitstream including video / image information is input, the decoding device (300) can restore the image by performing a process corresponding to the process performed in 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). Therefore, the processing unit for decoding may be, for example, a coding unit. The coding unit may be a coding tree unit or may be obtained by dividing the maximum coding unit according to a quad tree structure, a binary tree structure, and / or a ternary tree structure. In addition, the restored image signal decoded and output by the decoding device (300) can be reproduced through a reproduction device (not shown).

[0085] 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 the entropy decoding unit (310). For example, the entropy decoding unit (310) can parse the bitstream to derive information (e.g., video / image information) necessary for image restoration (or picture restoration). The video / image information may further include information on 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). In addition, the video / image information may further include general constraint information. The decoding device (300) can decode a picture further based on the information on the parameter set and / or the general constraint information. The signaling / received information and / or syntax elements described below can be decoded through the decoding procedure and obtained from the bitstream. For example, the entropy decoding unit (310) can decode information in the bitstream based on a coding method such as exponential Golomb coding, CAVLC, or CABAC, and output the values ​​of syntax elements required for image restoration and the quantized values ​​of transform coefficients for residuals. More specifically, the CABAC entropy decoding method receives a bin corresponding to each syntax element in the bitstream, determines a context model using information of the syntax element to be decoded and decoding information of the surrounding and decoding target blocks or information of symbols / bins decoded in the previous step, and predicts the occurrence probability of the bin according to the determined context model to 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 information of the decoded symbol / bin for the context model of the next symbol / bin after determining the context model. Information regarding prediction among the information decoded by the entropy decoding unit (310) is provided to the prediction unit (330), and residual values ​​on which entropy decoding is performed by the entropy decoding unit (310), i.e., quantized transform coefficients and related parameter information, can be input to the residual processing unit (320). The residual processing unit (320) can derive a residual signal (residual block, residual samples, residual sample array). In addition, information regarding filtering among the information decoded by the entropy decoding unit (310) 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 an entropy decoding unit (310). Meanwhile, the decoding device according to the present document may be called a video / video / picture decoding device, and the decoding device may be divided into an information decoder (video / video / picture information decoder) and a sample decoder (video / video / 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), the inverse transformation unit (322), the addition unit (340), the filtering unit (350), the memory (360), the inter prediction unit (332), and the intra prediction unit (331).

[0086] The inverse quantization unit (321) can inverse quantize the quantized transform coefficients and output the transform coefficients. The inverse quantization unit (321) can rearrange the quantized transform coefficients into a two-dimensional block form. In this case, the rearrangement can be performed based on the coefficient scanning order performed in the encoding device (200). The inverse quantization unit (321) can perform inverse quantization on the quantized transform coefficients using quantization parameters (e.g., quantization step size information) and obtain transform coefficients.

[0087] In the inverse transform unit (322), the transform coefficients can be inversely transformed to obtain a residual signal (residual block, residual sample array).

[0088] The prediction unit (330) can generate a prediction signal based on various prediction methods described below. For example, the prediction unit can apply intra prediction or inter prediction for prediction of a single block, and can also apply intra prediction and inter prediction simultaneously. This can be called combined inter and intra prediction (CIIP). In addition, the prediction unit can be based on an intra block copy (IBC) prediction mode or a palette mode for prediction of a block. The IBC prediction mode or palette mode can be used for content image / video coding such as games, such as screen content coding (SCC). IBC basically performs prediction within the current picture, but can be performed similarly to inter prediction in that it derives a reference block within the current picture. That is, IBC can utilize 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, information about the palette table and palette index may be signaled and included in the video / image information.

[0089] 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) can be equally applied to the intra prediction unit (331). The referenced samples may be located in the neighborhood of the current block or may be located away from it, depending on the prediction mode. In intra prediction, the prediction modes may include multiple non-directional modes and multiple directional modes. The intra prediction unit (331) can also determine the prediction mode applied to the current block by using the prediction mode applied to the neighboring blocks.

[0090] 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, in order to reduce the amount of motion information transmitted in the inter prediction mode, the motion information can be predicted in units of blocks, sub-blocks, or samples based on the correlation of the motion information between the neighboring blocks and the current block. The motion information can include a motion vector and a reference picture index. The motion information can further include information on the inter prediction direction (L0 prediction, L1 prediction, Bi prediction, etc.). In the case of inter prediction, the neighboring blocks can include spatial neighboring blocks existing in the current picture and temporal neighboring blocks existing in the reference picture. For example, the inter prediction unit (332) can 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 the information about the prediction can include information indicating the mode (technique) of inter prediction for the current block.

[0091] The addition unit (340) can generate a restoration signal (restored picture, restoration block, restoration sample array) by adding the acquired residual signal to the prediction signal (predicted block, prediction sample array) output from the prediction unit (330) (including the inter prediction unit (332) and / or the intra prediction unit (331)). When there is no residual for the block to be processed, such as when the skip mode is applied, the predicted block can be used as the restoration block. The description of the addition unit (250) can be equally applied to the addition unit (340). The addition unit (340) can 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 going through filtering as described below.

[0092] Meanwhile, LMCS (luma mapping with chroma scaling) may be applied during the picture decoding process.

[0093] The filtering unit (350) can improve subjective / objective image quality by applying filtering to the restored signal. For example, the filtering unit (350) can apply various filtering methods to the restored picture to generate a modified restored picture, and store the modified restored picture in the memory (360), specifically, in the DPB of the memory (360). The various filtering methods can include, for example, deblocking filtering, sample adaptive offset, adaptive loop filter, bilateral filter, etc.

[0094] The (modified) reconstructed 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 a block from which motion information is derived (or decoded) within the current picture and / or motion information of blocks within a picture that has already been reconstructed. The stored motion information can be transmitted to the inter prediction unit (332) to be used as motion information of a spatial neighboring block or motion information of a temporal neighboring block. The memory (360) can store reconstructed samples of reconstructed blocks within the current picture and transmit them to the intra prediction unit (331).

[0095] In this specification, the embodiments described in the filtering unit (260), the inter prediction unit (221), and the intra prediction unit (222) of the encoding device (200) can be applied to the filtering unit (350), the inter prediction unit (332), and the intra prediction unit (331) of the decoding device (300) in the same or corresponding manner, respectively.

[0096] Figure 4 illustrates an example of a hierarchical structure for coded video / images.

[0097] Referring to FIG. 4, the coded image is divided into a VCL (Video Coding Layer) that handles the decoding processing of the image and the image itself, a subsystem that transmits and stores the coded information, and a NAL (Network Abstraction Layer) that exists between the VCL and the subsystem and is responsible for network adaptation functions.

[0098] In VCL, VCL data containing compressed image data (slice data) can be generated, or a parameter set containing information such as a picture parameter set (PPS), a sequence parameter set (SPS), a video parameter set (VPS), etc., or an SEI (Supplemental Enhancement Information) message additionally required for the image decoding process can be generated.

[0099] In NAL, a NAL unit can be created by adding header information (NAL unit header) to an RBSP (Raw Byte Sequence Payload) generated from a VCL. At this time, RBSP refers to slice data, parameter sets, SEI messages, etc. generated from a VCL. The NAL unit header can include NAL unit type information that is specific to the RBSP data included in the NAL unit.

[0100] As illustrated in Fig. 4, NAL units can be divided into VCL NAL units and non-VCL NAL units according to the RBSP generated from VCL. A VCL NAL unit can refer to a NAL unit that contains information about a video (slice data), and a non-VCL NAL unit can refer to a NAL unit that contains information necessary for decoding a video (parameter set or SEI message).

[0101] The above-described VCL NAL units and non-VCL NAL units can be transmitted over a network by attaching header information according to the data specifications of the lower system. For example, NAL units can be transformed into data formats of a certain standard, such as the H.266 / VVC file format, RTP (Real-time Transport Protocol), TS (Transport Stream), etc., and transmitted over various networks.

[0102] As described above, a NAL unit can be specified as a NAL unit type according to the RBSP data structure included in the NAL unit, and information about the NAL unit type can be stored and signaled in the NAL unit header.

[0103] For example, depending on whether a NAL unit contains information about a picture (slice data), it can be broadly classified into VCL NAL unit types and Non-VCL NAL unit types. The VCL NAL unit type can be classified according to the nature and type of the picture contained in the VCL NAL unit, and the Non-VCL NAL unit type can be classified according to the type of parameter set, etc.

[0104] Below are examples of NAL unit types, specified by the type of parameter set included in the Non-VCL NAL unit type.

[0105] - APS (Adaptation Parameter Set) NAL unit: Type for NAL units containing APS

[0106] - DPS (Decoding Parameter Set) NAL unit: Type for NAL unit containing DPS

[0107] - VPS (Video Parameter Set) NAL unit: Type for NAL units containing VPS

[0108] - SPS (Sequence Parameter Set) NAL unit: Type for NAL units containing SPS

[0109] - PPS (Picture Parameter Set) NAL unit: Type for NAL units containing PPS

[0110] The above-described NAL unit types have syntax information for the NAL unit type, and the syntax information can be stored and signaled in the NAL unit header. For example, the syntax information can be nal_unit_type, and NAL unit types can be specified by the nal_unit_type value.

[0111] The slice header (slice header syntax, slice header information) may include information / parameters that are commonly applicable to the slices. The APS (APS syntax) or PPS (PPS syntax) may include information / parameters that are commonly applicable to one or more slices or pictures. The SPS (SPS syntax) may include information / parameters that are commonly applicable to one or more sequences. The VPS (VPS syntax) may include information / parameters that are commonly applicable to multiple layers. The DPS (DPS syntax) may include information / parameters that are commonly applicable to the entire video. The DPS may include information / parameters related to the concatenation of CVS (coded video sequence). In the present disclosure, the 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.

[0112] In the present disclosure, image / video information encoded in an encoding device and signaled in the form of a bitstream may include information related to partitioning within a picture, intra / inter prediction information, residual information, in-loop filtering information, etc., and 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.

[0113] Below, the SEI message related to the present invention will be described.

[0114] Table 1 shows an example of the SEI processing order SEI message syntax.

[0115] [Table 1]

[0116]

[0117] The SEI Processing Order (SPO) SEI message conveys information indicating the preferred processing order, as determined by the encoder (i.e., content producer), for a group of types of SEI messages that may exist in the CVS.

[0118] The semantics of SPO SEI messages use the notion of types for SEI messages. SEI messages with different payloadType values ​​are considered to be different types of SEI messages. Additionally, different SEI messages with the same payloadType value but distinguished by the values ​​of syntax elements in the SEI payload are considered to be different types of SEI messages. This distinction by the values ​​of syntax elements in the SEI payload is made by comparing the values ​​passed using the po_sei_prefix_data_bit[i][j] syntax elements (if present) or the values ​​passed within an SEI message within a processing order nested SEI message (if present). For example, NNPFC SEI messages can be distinguished by having different nnpfc_id values.

[0119] When both po_sei_wrapping_flag[ i ] and po_sei_prefix_flag[ i ] of the ith SEI message seiA in a specific SPO SEI message are 0, no SEI message seiB contained in the same SPO SEI message or another SPO SEI message within the current CVS shall satisfy all of the following conditions:

[0120] - The po_sei_payload_type[ i ] value of seiB is the same as that of seiA.

[0121] - The value of po_sei_wrapping_flag[ i ] of seiB is 0.

[0122] - The po_sei_prefix_flag[i] value of seiB is 1.

[0123] If an SPO SEI message with a specific po_id value exists in all access units of the CVS, the SPO SEI message with the specific po_id value must exist in the first access unit of the CVS in decoding order. The number of SEI messages specified within each SPO SEI message with the same po_id value and the payloadType codes of the SEI messages persist in decoding order in the current access unit until the end of the CVS in output order.

[0124] An SPO SEI message may carry one or more SEI prefix markers of a particular payloadType. When present, each SEI prefix marker is a bit string that follows the SEI payload syntax of the payloadType value and contains a number of complete syntax elements starting from the first syntax element of the SEI payload. These SEI prefix markers must provide sufficient information to determine a particular processing order for SEI message types that have the same payloadType value but different preferred processing orders.

[0125] po_id contains an identification number to identify the SPO SEI message.

[0126] A processing chain consists of a list of types of SEI messages identified by an SPO SEI message in the priority processing order specified in the SPO SEI message.

[0127] In the processing chain specified by the SPO SEI message, each type of SEI message is identified by the syntax elements po_sei_payload_type[i], po_sei_wrapping_flag[i], po_sei_processing_order[i], and, if present, po_num_bits_in_prefix_indication_minus1[i] and po_prefix_data_bit[i][j].

[0128] An SEI message type does not need to belong to any processing chain and may belong to multiple processing chains identified by SPO SEI messages with different po_id values.

[0129] Each SEI message of an SEI message type identified within a SPO SEI message has the same persistence scope as if that SEI message were transmitted outside of a SPO SEI message and not identified within the SPO SEI message.

[0130] Note that processing chains are interchangeable. That is, at most one processing chain is selected for application, or they can be complementary. That is, one or more processing chains, each producing a single output, are selected and applied individually.

[0131] po_num_sei_messages_minus2 plus 2 indicates the number of types of SEI messages whose preferred order of processing is indicated in the SPO SEI message.

[0132] po_sei_wrapping_flag[i], if its value is 1, specifies that there must be at least one processing order overlapping SEI message that has both of the following constraints:

[0133] - pon_target_po_id[j] with all j values ​​is equal to po_id.

[0134] - There exists a kth loop entry of the processing order nested SEI message such that the payload of the kth nested SEI message is equal to po_sei_payload_type[i] and pon_processing_order[k] is equal to po_sei_processing_order[i].

[0135] If po_sei_wrapping_flag[i] is 0, then an SEI message with payloadType equal to po_sei_payload_type[i] (and, if po_sei_wrapping_flag[i] is 1, then prefix data matching the value of po_sei_prefix_data_bit[i][j]) must be outside the processing order nested SEI message.

[0136] Note that po_sei_wrapping_flag[i], when its value is 1, allows SEI messages to be passed within a processing-order nested SEI message to prevent decoders that do not process SPO SEI messages from misinterpreting these SEI messages. Therefore, po_sei_wrapping_flag[i] is intended to be used in cases where a po_sei_wrapping_flag[i] of 0, when its value is 1, could cause unintended results for such decoders.

[0137] po_sei_importance_flag[i] indicates the importance determined by the encoder for the SEI message type with index i.

[0138] If a decoding system cannot interpret or does not support the functionality indicated by any given SEI message with po_sei_importance_flag[i] equal to 1, it must ignore the entire SPO SEI message.

[0139] po_sei_payload_type[i] specifies the payloadType value of the i-th type of the SEI message.

[0140] po_sei_prefix_flag[i], if its value is 1, specifies that the syntax elements po_num_bits_in_prefix_indication_minus1[i] and some syntax elements po_sei_prefix_data_bit[i][j] are present. po_sei_prefix_flag[i], if its value is 0, specifies that these syntax elements are not present.

[0141] SeiProcessingOrderSeiList is set to contain payloadType values ​​3, 4, 5, 19, 137, 142, 144, 147, 148, 149, 165, 177, 210, and 211. For each i in the range 0 to po_num_sei_messages_minus2, the value of po_sei_payload_type[i] must be equal to a value in SeiProcessingOrderSeiList.

[0142] po_sei_processing_order[i] represents the preferred order of processing of the ith type of SEI message for which preferred processing order information is provided in the SPO SEI message. For two different integer values ​​m and n, po_sei_processing_order[m], if its value is less than po_sei_processing_order[n], indicates that the SEI message type associated with index m should be processed before the SEI message type associated with index n. And po_sei_processing_order[m], if its value is po_sei_processing_order[n], indicates that there is no preferred order of processing between the SEI message types associated with indices m and n (e.g., they may both represent different attributes that can be applied at that stage or alternative processes that can be applied, or one may represent an attribute and the other a process).

[0143] For i greater than 0, po_sei_processing_order[i] must be greater than or equal to po_sei_processing_order[i - 1].

[0144] po_num_bits_in_prefix_indication_minus1[i] and po_sei_prefix_data_bit[i][j], if present, have the same semantics as the num_bits_in_prefix_indication_minus1[i] and sei_prefix_data_bit[i][j] syntax elements of an SEI prefix indication SEI message, with prefix_sei_payload_type replaced by po_sei_payload_type[i].

[0145] If one or more SPO SEI messages with a particular po_id value exist in the CVS, then for the po_num_sei_messages_minus2 values ​​and for each value of i, the values ​​of po_sei_wrapping_flag[i], po_sei_prefix_flag[i], po_sei_importance_flag[i], po_sei_payload_type[i], po_sei_processing_order[i] must be identical to those of other SPO SEI messages in the CVS with the same po_id value.

[0146] po_byte_alignment_bit_equal_to_one must be 1.

[0147] Table 2 shows an example of the processing order nested SEI message syntax.

[0148] [Table 2]

[0149]

[0150] A Processing Order Overlap (PON) SEI message contains one or more SEI messages that must apply only to a portion of the processing chain identified by the associated SEI Processing Order SEI message and must not be applied in a manner that contradicts the processing chain identified by the associated SEI Processing Order SEI message.

[0151] SEI messages included in a PON SEI message are referred to as PON-nested SEI messages.

[0152] Note that the encoder can include multiple PON SEI messages in the same access unit. For example, the first PON SEI message in an access unit can include a PON-nested message that applies to multiple processing chains and one or more other PON SEI messages in the same access unit that apply to a single processing chain.

[0153] It is a requirement of bitstream conformance that the semantics and effects of non-PON-nested SEI messages must not depend on any PON-nested SEI message.

[0154] - If a neural network post-processing filter feature SEI message with a specific nnpfc_id value exists as a PON-nested SEI message, all related neural network post-processing filter activation SEI messages with an nnpfa_target_id equal to that nnpfc_id value must also be PON-nested SEI messages.

[0155] - When the nnpfa_persistence_flag value is 1 and the neural network postprocessing filter activation (NNPFA) SEI message with a specific nnpfa_target_id value is not a PON-SEI message, the NNPFA SEI message cannot be associated with a PON-overlap SEI message when an NNPFA SEI message with the same nnpfa_target_id value exists in the next image in the output order in the same CLVS (if any).

[0156] - If a film grain characteristics SEI message with the fg_characteristics_persistence_flag value of 1 is not a PON-overlapped SEI message, there must not be any PON-overlapped SEI messages associated with that film grain characteristics SEI message within the same CLVS.

[0157] - If a frame packing array SEI message exists that is not a PON-overlapped SEI message and has the fp_arrangement_persistence_flag value of 1, there must not be a related frame packing array SEI message within the same CLVS that has the fp_arrangement_cancel_flag value of 1 or has the same fp_arrangement_id value.

[0158] - If the ccv_persistence_flag value is 1 and a content color volume SEI message other than a PON-overlapped SEI message exists, then a related frame packing array SEI message must not exist as a PON-overlapped SEI message within the same CLVS.

[0159] - If the erp_persistence_flag value is 1 and there is an equirectangular projection SEI message that is not a PON-overlap SEI message, then no related equirectangular projection SEI message must exist as a PON-overlap SEI message within the same CLVS.

[0160] - If the gcmp_persistence_flag value is 1 and a generalized cubemap projection SEI message other than a PON-nested SEI message exists, then no related generalized cubemap projection SEI message must exist as a PON-nested SEI message within the same CLVS.

[0161] - If the sphere_rotation_persistence_flag value is 1 and a sphere rotation SEI message other than a PON-overlap SEI message exists, then no related sphere rotation SEI message must exist as a PON-overlap SEI message within the same CLVS.

[0162] - If the rwp_persistence_flag value is 1 and there is a region-wise packing SEI message other than a PON-overlapping SEI message, then no related region-wise packing SEI message must exist as a PON-overlapping SEI message within the same CLVS.

[0163] - If the omni_viewport_persistence_flag value is 1 and an omnidirectional viewport SEI message other than a PON-overlapping SEI message exists, then no related omnidirectional viewport SEI message must exist as a PON-overlapping SEI message within the same CLVS.

[0164] - If the sari_persistence_flag value is 1 and a sample aspect ratio SEI message other than a PON-overlap SEI message exists, then no related sample aspect ratio SEI message must exist as a PON-overlap SEI message within the same CLVS.

[0165] - If there is an annotated regions SEI message that is not a PON-nested SEI message, then the related annotated regions SEI message must not exist as a PON-nested SEI message within the same CLVS.

[0166] - If there is an alpha channel information SEI message other than a PON-overlap SEI message, the related alpha channel information SEI message must not exist as a PON-overlap SEI message within the same CLVS.

[0167] - If a display orientation SEI message other than a PON-overlap SEI message exists, a related display orientation SEI message must not exist as a PON-overlap SEI message within the same CLVS.

[0168] - If a color transform indication SEI message exists that is not a PON-nested SEI message and has a color_transform_persistence_flag value of 1, there must not be a related color transform SEI message within the same CLVS that is a PON-nested SEI message with a color_transform_cancel_flag value of 1 or has the same color_transform_id value.

[0169] pon_num_po_ids_minus1 plus 1 specifies the number of SEI processing order SEI messages associated with this PON SEI message.

[0170] pon_target_po_id[i] represents the po_id of the SEI message of the i-th associated SEI processing order.

[0171] pon_num_seis_minus1 plus 1 specifies the number of PON-nested SEI messages contained in this PON SEI message.

[0172] pon_processing_order[i] specifies the position of the processing-order-nested SEI message contained in this SEI message within the processing order defined by the associated SEI processing-order SEI message. If i is greater than 0, pon_processing_order[i] must be greater than or equal to pon_processing_order[i - 1].

[0173] For each associated SEI Processing Order SEI message, there shall be at least one i value in the range 0 to pon_num_seis_minus1 of a PON SEI message with some entry k for which all of the following are true:

[0174] - po_sei_processing_order[k] is the same as pon_processing_order[i].

[0175] - po_sei_payload_type[k] is equal to the payloadType value of the ith PON-nested SEI message.

[0176] - If po_sei_prefix_flag[k] is 1, then for i in the range from 0 to po_num_bits_in_prefix_indication_minus1[k], po_sei_prefix_data_bit[k][j] contains content equal to po_num_bits_in_prefix_indication_minus1[k] plus 1 initial bits of the SEI message payload of the ith PON-nested SEI message.

[0177] The ith PON-nested SEI message shall be applied as the kth loop entry of the associated SEI processing sequence SEI message.

[0178] In the design described above, the SEI Processing Order (SPO) SEI message and the Processing Order Nesting (PON) SEI message are closely related and may require each other in some cases. The current semantics for the po_sei_wrapping_flag[i] of the SPO SEI message are as follows.

[0179] If the value of po_sei_wrapping_flag[i] is 1, it indicates that there must be at least one PON SEI message that satisfies both conditions below.

[0180] For any value j, pon_target_po_id[j] is equal to po_id.

[0181] The PON SEI message must have a kth repetition item, the payloadType of the kth nested SEI message is equal to po_sei_payload_type[i], and pon_processing_order[k] is equal to po_sei_processing_order[i].

[0182] If the value of po_sei_wrapping_flag[i] is 0, an SEI message with payloadType equal to po_sei_payload_type[i] must exist outside the Processing Order Overlap (PON) SEI message (and if the value of po_sei_prefix_flag[i] is 1, there must be prefix data matching the value of po_sei_prefix_data_bit[i][j]).

[0183] Note that if po_sei_wrapping_flag[i] is 1, this allows SEI messages to be contained within Processing Order Overlap (PON) SEI messages to prevent decoders that do not process SPO SEI messages from misinterpreting the SEI message. Therefore, the case where po_sei_wrapping_flag[i] is 1 is designed to be used in situations where a decoder might produce undesirable results when po_sei_wrapping_flag[i] is 0.

[0184] The above semantics can be interpreted as requiring that at least one Processing Order Overlap (PON) SEI message containing the ith SEI message must be present when the value of the syntax element is 1. If this is the design intent, we believe that this design is undesirable because problems may arise if a PON SEI message is removed from the bitstream. To satisfy the above semantics, if a PON SEI message is removed from the bitstream, all target SPO SEI messages associated with the removed PON SEI message must also be modified.

[0185] A similar problem can also occur when po_sei_wrapping_flag[i] is set to 0. The current semantics can be interpreted as requiring the ith SEI message to be present in the bitstream. However, we believe the intention is that the processing order of the ith SEI message applies only when that SEI message is present, not that the SEI message itself must always be present.

[0186] One embodiment provides a solution to the problem described above. Each embodiment may be performed individually or in combination with two or more embodiments.

[0187] The embodiments are summarized as follows. The operations and configurations described below form an embodiment together with the operations and configurations described above, unless they are inconsistent with the operations and configurations described above, and the operations and configurations described below do not form a separate embodiment that is distinct from the operations and configurations described above.

[0188] 1. Modify the semantics of po_sei_wrapping_flag[i] to indicate where the SEI message that can be considered as the i-th SEI in the processing chain specified by the SPO SEI message exists. That is, if the value of po_sei_wrapping_flag[i] is 1, the corresponding SEI message exists within a PON SEI message, and if the value of po_sei_wrapping_flag[i] is not 1, the corresponding SEI message does not exist within a PON SEI message.

[0189] 2. Note that even if the value of po_sei_wrapping_flag[i] is 1, an SEI message with prefix data matching the value of po_sei_prefix_data_bit[i][j], payloadType equal to po_sei_payload_type[i], and po_sei_prefix_flag[i] equal to 1 may exist in the CVS without being included in the PON SEI message. However, such an SEI message shall not be considered as the i-th SEI message in the processing chain specified by the SPO SEI message.

[0190] 3. When verifying bitstream conformance, the decoder must not raise an error even if it cannot find an SEI message marked as wrapped in an SPO message (i.e., when the value of po_sei_wrapping_flag[i] is 1) in the current CVS.

[0191] 4. The semantics of the syntax element po_sei_wrapping_flag[i] are modified to be more flexible, allowing the ith SEI message to not be present in the bitstream. However, if the SEI message is present, it is still required to be contained within at least one PON SEI message.

[0192] 5. In other words, the value of the syntax element po_sei_wrapping_flag[i] has the following meaning:

[0193] If the value of po_sei_wrapping_flag[i] is 1, it means that if the i-th SEI message exists in the CVS, it must be included in the PON SEI message.

[0194] If the value of po_sei_wrapping_flag[i] is 0, it means that if the i-th SEI message exists in the CVS, it should not be included in the PON SEI message.

[0195] The embodiments are described in detail below. One embodiment provides an explanation of the summary described above.

[0196] According to one embodiment, if the value of po_sei_wrapping_flag[i] is 1, it specifies that an SEI message not included in a PON SEI message is not applied to the i-th SEI message type in the processing chain specified by this SPO SEI message. If the value of po_sei_wrapping_flag[i] is 0, it specifies that an SEI message included in a PON SEI message is not applied to the i-th SEI message type in the processing chain specified by this SPO SEI message.

[0197] Note that if po_sei_wrapping_flag[i] is 1, the SEI message can be wrapped within a Processing Order Overlap (PON) SEI message to prevent decoders that do not process SPO SEI messages from misinterpreting the SEI message. Therefore, the case where po_sei_wrapping_flag[i] is 1 is intended to be used in situations where unintended results may occur in the decoder when po_sei_wrapping_flag[i] is 0.

[0198] According to one embodiment, if the po_sei_wrapping_flag[i] value is 1, this indicates that the SEI message applied as the i-th SEI message in the processing chain specified in this SPO SEI message is an SEI message included in a PON SEI message that satisfies all of the following conditions:

[0199] - For any value j, pon_target_po_id[j] is equal to po_id.

[0200] - The Processing Order Nested (PON) SEI message has a kth repetition item, the payloadType of the kth nested SEI message is equal to po_sei_payload_type[i], and pon_processing_order[k] is equal to po_sei_processing_order[i].

[0201] If the po_sei_wrapping_flag[i] value is 0, this indicates that the SEI message applied as the i-th SEI message in the processing chain specified in this SPO SEI message is an SEI message that is not included in a PON SEI message and satisfies all of the following conditions.

[0202] - The payloadType of the SEI message is po_sei_payload_type[i].

[0203] - If the po_sei_prefix_flag[i] value is 1, the prefix data of the SEI message matches the po_sei_prefix_data_bit[i][j] value.

[0204] Note that if po_sei_wrapping_flag[i] is 1, the SEI message can be wrapped within a Processing Order Overlap (PON) SEI message to prevent decoders that do not process SPO SEI messages from misinterpreting the SEI message. Therefore, the case where po_sei_wrapping_flag[i] is 1 is designed to be used in situations where unintended results may occur in the decoder when po_sei_wrapping_flag[i] is 0.

[0205] In one embodiment, if the po_sei_wrapping_flag[i] value is 1, then if the i-th SEI message exists in the CVS, that SEI message must be contained in one or more Processing Order Nesting SEI messages that satisfy all of the following conditions:

[0206] - For any value j, pon_target_po_id[j] is equal to po_id.

[0207] - The Processing Order Nested (PON) SEI message has a kth repetition item, the payloadType of the kth nested SEI message is equal to po_sei_payload_type[i], and pon_processing_order[k] is equal to po_sei_processing_order[i].

[0208] If po_sei_wrapping_flag[i] is 0, and there is an SEI message whose payloadType is equal to po_sei_payload_type[i] (and po_sei_prefix_flag[i] is 1 and the prefix data matches po_sei_prefix_data_bit[i][j]), then that SEI message must be outside the Processing Order Nesting SEI message.

[0209] Note that if po_sei_wrapping_flag[i] is 1, the SEI message can be wrapped within a Processing Order Overlap (PON) SEI message to prevent decoders that do not process SPO SEI messages from misinterpreting the SEI message. Therefore, the case where po_sei_wrapping_flag[i] is 1 is designed to be used in situations where unintended results may occur in the decoder when po_sei_wrapping_flag[i] is 0.

[0210] FIG. 5 is a diagram illustrating a method for decoding image information according to one embodiment of the present disclosure.

[0211] The terms or names described in FIG. 5 (e.g., names of syntax elements or names of variables, etc.) are merely examples, and the technical features of the present disclosure are not limited to the terms described in FIG. 5. For example, the image information described in FIG. 5 may include various information according to the embodiments described in the present disclosure, and may include information described in at least one of the tables described above.

[0212] The decoding method (S500) may include the operations described below. The operations described below are not essential components of the decoding method according to an embodiment, and at least some of the operations described below may be omitted. Furthermore, the operations described below are not sufficient components of the decoding method according to an embodiment, and the operations described above may be added. Furthermore, the operations described below form an embodiment together with the operations described above, unless they contradict the operations described above, and do not form a separate embodiment distinct from the operations described above.

[0213] The decoding method (S500) can be executed by a decoding device including a memory and a processor electrically connected to the memory, and can be executed by, for example, a processor.

[0214] The decoding device can obtain information about the SEI (supplemental enhancement information) processing order (S510).

[0215] For example, a processor of a decoding device may obtain image information including a plurality of SEI messages, an SEI processing order message indicating a processing order according to payload types of the plurality of SEI messages, and a processing order nested message including nested SEI messages belonging to a processing chain specified by the SEI processing order message. Here, the processing chain may be composed of a list of types of SEI messages identified by the SEI processing order message.

[0216] The multiple SEI messages may be SEI messages having different payload types. For example, the multiple SEI messages may include SEI messages having different payload types and / or SEI messages having the same payload type.

[0217] An SEI processing order message may contain information about the processing order for a group of types of SEI messages that may be present in a coded video sequence (CVS) or a coded layer video sequence (CLVS).

[0218] The SEI processing order message may have various names, such as SEI processing order SEI message or SPO (SEI processing order) SEI message, and the names are not limited.

[0219] The SEI processing order message can take various forms. For example, the SEI processing order message can be a syntax element or a syntax structure containing one or more syntax elements. Furthermore, the SEI processing order message can be a raw byte sequence payload (RBSP) containing one or more syntax elements or one or more syntax structures. For example, the SEI processing order message can be expressed as sei_processing_order( ), but is not limited thereto.

[0220] The SEI processing order message may include identification information, wrapping flag information, payload type information, prefix flag information, and / or processing order information.

[0221] The identification information may include an identifier (e.g., an identification number, an identification letter, and / or an identification symbol) for identifying an SEI processing sequence message from other SEI processing sequence messages.

[0222] Identification information can take various forms and be expressed by various names. For example, identification information can be a syntax element or a syntax structure containing one or more syntax elements. For example, identification information as a syntax element can be expressed as, but is not limited to, po_id.

[0223] The wrapping flag information may indicate whether an SEI message belonging to a processing chain specified by an SEI processing order message is included in a processing order nested message.

[0224] For example, a value of 1 in the wrapping flag information may indicate that an SEI message belonging to a processing chain specified by an SEI processing order message is included in a processing order nested message, that is, the processing order nested message includes an SEI message belonging to a processing chain specified by an SEI processing order message.

[0225] Additionally, a value of 0 in the wrapping flag information may indicate that an SEI message belonging to the processing chain specified by the SEI processing order message is not included in the processing order nested message, i.e., that the processing order nested message does not include an SEI message belonging to the processing chain specified by the SEI processing order message.

[0226] However, this is not limited to this, and alternatively, specifying that the value of the wrapping flag information is 1 may be changed to specifying that the value of the wrapping flag information is 0.

[0227] In addition, if the value of the wrapping flag information is 1, the target identification information of the processing order nested message is the same as the identification information of the SEI processing order message, the payload type of the nested SEI message is the same as the payload type specified by the SEI processing order message, and the processing order of the nested SEI message may be the same as the processing order specified by the SEI processing order message.

[0228] Wrapping flag information can take various forms and be expressed by various names. For example, wrapping flag information can be a syntax element or a syntax structure containing one or more syntax elements. For example, wrapping flag information as a syntax element can be a one-bit wrapping flag or a two-bit wrapping indicator. Wrapping flag information as a syntax element can be expressed as, for example, po_sei_wrapping_flag[i], but is not limited thereto.

[0229] Payload type information can indicate the type of an SEI message. For example, payload type information can specify the payloadType value of an SEI message.

[0230] Payload type information can take various forms and be expressed by various names. For example, payload type information can be a syntax element or a syntax structure containing one or more syntax elements. For example, payload type information can be expressed as po_sei_payload_type[i], but is not limited thereto.

[0231] The prefix flag information may indicate whether prefix information corresponding to the type of the corresponding SEI message exists. Here, the prefix information may include the bit number information of the prefix indication po_num_bits_in_prefix_indication_minus1[ i ] and the prefix data bit po_sei_prefix_data_bit[ i ][ j ]. For example, a value of the prefix flag information of 1 may indicate that prefix information corresponding to the type of the corresponding SEI message exists. In addition, a value of the prefix flag information of 0 may indicate that prefix information corresponding to the type of the corresponding SEI message does not exist. However, the present invention is not limited thereto, and alternatively, what the value of the prefix flag information of 1 indicates may be changed from what the value of the prefix flag information of 0 indicates.

[0232] Prefix flag information can take various forms and be expressed by various names. For example, prefix flag information can be a syntax element or a syntax structure including one or more syntax elements. For example, prefix flag information as a syntax element can be a one-bit prefix flag or a two or more-bit prefix indicator. Prefix flag information as a syntax element can be expressed as, for example, po_sei_prefix_flag[i], but is not limited thereto.

[0233] The processing order information may indicate the processing order corresponding to the type of the corresponding SEI message. The smaller the value of the processing order information for a specific type, the earlier the SEI message of that specific type may be processed. In other words, if the value of the processing order information for the first type is smaller than the value of the processing order information for the second type, the SEI message of the first type may be processed earlier than the SEI message of the second type.

[0234] Processing order information can take various forms and be expressed by various names. For example, processing order information can be a syntax element or a syntax structure containing one or more syntax elements. For example, processing order information can be expressed as po_sei_processing_order[i], but is not limited thereto.

[0235] A processing order nested message may be associated with a particular SEI processing order message and may include information about the processing order for SEI messages that act as part of the processing chain identified by the particular SEI processing order message (hereinafter referred to as a “nested SEI message”) and types of those SEI messages.

[0236] A processing order nesting message may be called various names, such as a processing order nesting SEI message or a FON (processing order nesting) SEI message, and is not limited to that name as long as it contains information about the processing order for nested SEI messages and types of nested SEI messages.

[0237] A nested SEI message does not depend on any SEI message that is not included in the processing order of the nested message. Specifically, the semantics and effects of a non-PON-nested SEI message do not affect any PON-nested SEI message.

[0238] The processing order nesting message may be called by various names, such as a processing order nesting SEI message or a PON (processing order nesting) SEI message, but is not limited to these names.

[0239] A processing order nesting message can take various forms and be expressed by various names. For example, a processing order nesting message can be a syntax element or a syntax structure containing one or more syntax elements. Furthermore, a processing order nesting message can be a raw byte sequence payload (RBSP) containing one or more syntax elements or one or more syntax structures. For example, a processing order nesting message can be expressed as, but is not limited to, processing_order_nesting( ).

[0240] A processing order nested message may include target identification information, nested order information, and / or nested SEI messages.

[0241] The target identification information may include an identifier (e.g., an identification number, an identification letter, and / or an identification symbol) for identifying the SEI processing sequence message associated with the processing sequence nesting message.

[0242] Target identification information can take various forms and be expressed by various names. For example, target identification information can be a syntax element or a syntax structure containing one or more syntax elements. For example, target identification information as a syntax element can be expressed as, but is not limited to, pon_target_po_id[ i ].

[0243] Nesting order information can specify the position of a nested SEI message within the processing order defined by the SEI processing order message associated with the processing order nesting message.

[0244] Nesting order information can take various forms and be expressed by various names. For example, nesting order information can be a syntax element or a syntax structure containing one or more syntax elements. For example, nesting order information can be expressed as pon_processing_order[i], but is not limited thereto.

[0245] A nested SEI message represents an SEI message contained in a processing order nested message.

[0246] The decoding device can determine the processing order for the SEI message (S520).

[0247] For example, a processor of a decoding device may determine a processing order for an SEI message based on an SEI processing order message. The processor may determine a processing order for a group of SEI message types based on processing order information included in the SEI processing order message. Furthermore, the processor may process SEI messages according to the determined processing order.

[0248] In this way, SEI processing order messages can be associated with processing order nested messages.

[0249] Here, SEI messages including SEI processing order messages and processing order nested messages are optional. SEI messages may be selectively transmitted at the encoding device level or at the network entity transmitting the video information. In other words, SEI messages may be dropped by the encoding device, the transmission device, or the network entity.

[0250] For example, an SEI message belonging to a processing chain specified by an SEI processing order message may be dropped by an encoding device, a transmission device, or a network entity and may not be included in the image information acquired by the decoding device.

[0251] It may be permissible for an SEI message belonging to a processing chain specified by an SEI processing order message not to be included in the image information acquired by the decoding device. In other words, an SEI message belonging to a processing chain specified by an SEI processing order message may be optionally present in the image information.

[0252] For example, an SEI message within a processing chain specified by an SEI processing order message may include an SEI message that is present in the image information or may include an SEI message that is not present in the image information. Even if an SEI message within a processing chain specified by an SEI processing order message includes an SEI message that is not present in the image information, a processor of a decoding device may continue to process the SEI processing order message without outputting an error or stopping processing the SEI processing order message.

[0253] Additionally, the payload type information of the SEI processing order message may include type information of an SEI message present in the video information or may include type information of an SEI message not present in the video information. Even if the payload type information of the SEI processing order message includes type information of an SEI message not present in the video information, the processor of the decoding device may continue to process the SEI processing order message without outputting an error or stopping processing the SEI processing order message.

[0254] In particular, the wrapping flag information may indicate whether an SEI message belonging to a processing chain specified by an SEI processing order message is included in a processing order nesting message when the SEI message is present in the image information.

[0255] For example, a value of the wrapping flag information of 1 may indicate that, when an SEI message belonging to a processing chain specified by an SEI processing order message exists in the image information, the corresponding SEI message is included in the processing order nested message. In other words, when the value of the wrapping flag information of 1, it is allowed that an SEI message belonging to a processing chain specified by an SEI processing order message does not exist in the image information, but if the corresponding SEI message exists in the image information, the corresponding SEI message is included in the processing order nested message.

[0256] In addition, a value of the wrapping flag information of 0 may indicate that, when an SEI message belonging to a processing chain specified by an SEI processing order message exists in the image information, the corresponding SEI message is not included in the processing order nesting message. In other words, when the value of the wrapping flag information of 0 is 0, it is allowed that an SEI message belonging to a processing chain specified by an SEI processing order message does not exist in the image information, but if the corresponding SEI message exists in the image information, the corresponding SEI message is not included in the processing order nesting message.

[0257] As described above, it is permissible for an SEI message belonging to a processing chain specified by an SEI processing order message to not be included in the image information acquired by the decoding device, thereby providing flexibility in the processing of the SEI processing order message and / or the processing order overlap message. As a result, the occurrence of errors or interruptions in coding operations can be reduced, thereby further improving coding efficiency and speed.

[0258] FIG. 6 is a diagram illustrating a method for encoding image information according to one embodiment of the present disclosure.

[0259] The terms or names described in FIG. 6 (e.g., names of syntax elements or names of variables, etc.) are merely examples, and the technical features of the present disclosure are not limited to the terms described in FIG. 6. For example, the image information described in FIG. 6 may include various information according to the embodiments described in the present disclosure, and may include information described in at least one of the tables described above.

[0260] The encoding method (S600) may include the operations described below. The operations described below do not constitute essential components of the decoding method according to an embodiment, and at least some of the operations described below may be omitted. In addition, the operations described below do not constitute sufficient components of the encoding method according to an embodiment, and the operations described above may be added. Furthermore, the operations described below form an embodiment together with the operations described above, unless they contradict the operations described above, and do not form a separate embodiment distinct from the operations described above.

[0261] The encoding device can generate a supplemental enhancement information (SEI) message (S610).

[0262] For example, a processor of an encoding device may generate multiple SEI messages. The multiple SEI messages may be SEI messages having different payload types. For example, the multiple SEI messages may include SEI messages having different payload types and / or SEI messages having the same payload type.

[0263] The encoding device can determine the processing order for the SEI message (S620).

[0264] For example, a processor of an encoding device can determine the processing order for a group of types of SEI messages.

[0265] The encoding device can generate information about the SEI processing order (S630).

[0266] For example, a processor of an encoding device may generate information about an SEI processing order based on a processing order for a group of types of SEI messages. Here, the information about the SEI processing order may include an SEI processing order message indicating a processing order according to payload types of a plurality of SEI messages, and nested SEI messages belonging to a processing chain specified by the SEI processing order message.

[0267] An SEI processing order message may contain information about the processing order for a group of types of SEI messages that may be present in a coded video sequence (CVS) or a coded layer video sequence (CLVS).

[0268] The SEI processing order message can take various forms and have various names, as described above with reference to FIG. 5.

[0269] The SEI processing order message may include identification information, wrapping flag information, payload type information, prefix flag information, and / or processing order information, as previously described with reference to FIG. 5.

[0270] The identification information may be the same as the identification information described above with reference to FIG. 5, and the description of the identification information is replaced with the description of the identification information described with reference to FIG. 5.

[0271] The wrapping flag information may indicate whether an SEI message belonging to a processing chain specified by an SEI processing order message is included in a processing order nested message.

[0272] For example, a value of 1 in the wrapping flag information may indicate that an SEI message belonging to a processing chain specified by an SEI processing order message is included in a processing order nested message, that is, the processing order nested message includes an SEI message belonging to a processing chain specified by an SEI processing order message.

[0273] Additionally, a value of 0 in the wrapping flag information may indicate that an SEI message belonging to the processing chain specified by the SEI processing order message is not included in the processing order nested message, i.e., that the processing order nested message does not include an SEI message belonging to the processing chain specified by the SEI processing order message.

[0274] However, this is not limited to this, and alternatively, specifying that the value of the wrapping flag information is 1 may be changed to specifying that the value of the wrapping flag information is 0.

[0275] Wrapping flag information can take various forms and be expressed by various names. For example, wrapping flag information can be a syntax element or a syntax structure containing one or more syntax elements. For example, wrapping flag information as a syntax element can be a one-bit wrapping flag or a two-bit wrapping indicator. Wrapping flag information as a syntax element can be expressed as, for example, po_sei_wrapping_flag[i], but is not limited thereto.

[0276] In addition, if the value of the wrapping flag information is 1, the target identification information of the processing order nested message is the same as the identification information of the SEI processing order message, the payload type of the nested SEI message is the same as the payload type specified by the SEI processing order message, and the processing order of the nested SEI message may be the same as the processing order specified by the SEI processing order message.

[0277] The payload type information may be the same as the payload type information described with FIG. 5, and the description of the payload type information is replaced with the description of the payload type information described with FIG. 5.

[0278] The prefix flag information may be the same as the prefix flag information described with FIG. 5, and the description of the prefix flag information is replaced with the description of the prefix flag information described with FIG. 5.

[0279] The processing order information may be the same as the processing order information described with FIG. 5, and the description of the prefix flag information is replaced with the description of the processing order information described with FIG. 5.

[0280] A processing order nested message may be associated with a particular SEI processing order message and may include information about the processing order for SEI messages that act as part of the processing chain identified by the particular SEI processing order message (hereinafter referred to as a “nested SEI message”) and types of those SEI messages.

[0281] The processing order nested message can take various forms and have various names, as described above with reference to FIG. 5.

[0282] The processing order nested message may include target identification information, nested order information, and / or nested SEI messages as described above with reference to FIG. 5.

[0283] The target identification information may be the same as the target identification information described with reference to FIG. 5, and the description of the target identification information is replaced with the description of the target identification information described with reference to FIG. 5.

[0284] The overlapping order information may be the same as the overlapping order information described with FIG. 5, and the description of the overlapping order information is replaced with the description of the overlapping order information described with FIG. 5.

[0285] A nested SEI message represents an SEI message contained in a processing order nested message.

[0286] The encoding device can encode image information including an SEI message, an SEI processing order message, and / or a processing overlap message (S640).

[0287] For example, image information including SEI messages, SEI processing order messages, and / or processing overlap messages of an encoding device can be encoded.

[0288] In this way, SEI processing order messages can be associated with processing order nested messages.

[0289] At this time, SEI messages including SEI processing order messages and processing order overlap messages are optional. SEI messages can be selectively transmitted at the encoding device level. In other words, SEI messages can be dropped by the encoding device.

[0290] For example, an SEI message belonging to a processing chain specified by an SEI processing order message may be dropped by the encoding device.

[0291] It may be permissible for an SEI message belonging to a processing chain specified by an SEI processing order message not to be included in the video information encoded by the encoding device. In other words, an SEI message belonging to a processing chain specified by an SEI processing order message may be optionally present in the video information.

[0292] For example, an SEI message within a processing chain specified by an SEI processing order message may include an SEI message that is present in the image information or may include an SEI message that is not present in the image information. Even if an SEI message within a processing chain specified by an SEI processing order message includes an SEI message that is not present in the image information, a processor of an encoding device may continue to encode the SEI processing order message without outputting an error or stopping encoding the SEI processing order message.

[0293] Additionally, the payload type information of the SEI processing order message may include type information of an SEI message present in the video information or may include type information of an SEI message not present in the video information. Even if the payload type information of the SEI processing order message includes type information of an SEI message not present in the video information, the processor of the encoding device may continue encoding the SEI processing order message without outputting an error or stopping encoding the SEI processing order message.

[0294] In particular, the wrapping flag information may indicate whether an SEI message belonging to a processing chain specified by an SEI processing order message is included in a processing order nesting message when the SEI message is present in the image information.

[0295] For example, a value of the wrapping flag information of 1 may indicate that, when an SEI message belonging to a processing chain specified by an SEI processing order message exists in the image information, the corresponding SEI message is included in the processing order nested message. In other words, when the value of the wrapping flag information of 1, it is allowed that an SEI message belonging to a processing chain specified by an SEI processing order message does not exist in the image information, but if the corresponding SEI message exists in the image information, the corresponding SEI message is included in the processing order nested message.

[0296] In addition, a value of the wrapping flag information of 0 may indicate that, when an SEI message belonging to a processing chain specified by an SEI processing order message exists in the image information, the corresponding SEI message is not included in the processing order nesting message. In other words, when the value of the wrapping flag information of 0 is 0, it is allowed that an SEI message belonging to a processing chain specified by an SEI processing order message does not exist in the image information, but if the corresponding SEI message exists in the image information, the corresponding SEI message is not included in the processing order nesting message.

[0297] As described above, it is allowed that an SEI message belonging to a processing chain specified by an SEI processing order message is not included in the image information coded by the encoding device, thereby providing flexibility in encoding the SEI processing order message and / or the processing order overlap message. As a result, the occurrence of errors or interruptions in the coding operation can be reduced, thereby further improving the coding efficiency and further increasing the coding speed.

[0298] A bitstream is generated based on image information encoded according to the encoding method (S600) described above, and the bitstream can be stored in a computer-readable storage medium.

[0299] Additionally, a bitstream is generated based on the image information encoded according to the encoding method (S600) described above, and the bitstream can be transmitted through a transmission unit and / or a transmission medium.

[0300] The terms or names described below (e.g., names of syntax elements or names of variables, etc.) are merely examples, and the technical features of the present disclosure are not limited to the terms described below. For example, the image information described below may include various information according to the embodiments described in the present disclosure, and may include information described in at least one of the tables described above.

[0301] The operations described below are not essential components of an embodiment, and at least some of the operations described below may be omitted. Furthermore, the operations described below are not sufficient components of an embodiment, and previously described operations may be added. Furthermore, the operations described below, unless they contradict the previously described operations, form an embodiment together with the previously described operations, and do not form a separate embodiment distinct from the previously described operations.

[0302] As described with reference to FIGS. 5 and 6, the image information may include a plurality of SEI messages, an SEI processing order message, and / or a processing order nested message. The SEI processing order message may include identification information, wrapping flag information, payload type information, prefix flag information, and / or processing order information. Additionally, the processing order nested message may include target identification information, nested order information, and / or nested SEI messages.

[0303] Here, an SEI message including an SEI processing order message and a processing order nested message may be dropped by an encoding device, a transmission device, or a network entity, and may not be included in the image information obtained by a decoding device. For example, an SEI message belonging to a processing chain specified by an SEI processing order message may be dropped by an encoding device, a transmission device, or a network entity. In order to ensure flexibility and stability of operations of an encoding device and a decoding device, it may be allowed that an SEI message including a processing order nested message associated with an SEI processing order message may not be included in the image information coded by an encoding device or the image information obtained by a decoding device.

[0304] For example, a first SEI processing order message, a second SEI processing order message, a first SEI message, a second SEI message, a first processing order nested message, and a second processing order nested message may be generated.

[0305] The value of the payload type information of the first SEI message A1 may be 120, and the value of the payload type information of the second SEI message A2 may be 220.

[0306] The information included in the first SEI processing order message and the second SEI processing order message can be shown in Tables 3 and 4, respectively.

[0307] [Table 3]

[0308]

[0309] [Table 4]

[0310]

[0311] For example, as shown in Tables 3 and 4, a first SEI processing order message having identification information of 00 may include order information about an SEI message having a wrapping flag information value of 1 and a payload type information value of 100, order information about an SEI message having a wrapping flag information value of 0 and a payload type information value of 120, and order information about an SEI message having a wrapping flag information value of 1 and a payload type information value of 150.

[0312] A second SEI processing order message having identification information of 10 may include order information regarding an SEI message having a wrapping flag information value of 1 and a payload type information value of 200, order information regarding an SEI message having a wrapping flag information value of 0 and a payload type information value of 220, and order information regarding an SEI message having a wrapping flag information value of 1 and a payload type information value of 250.

[0313] The information included in the first processing order nested message and the second processing order nested message can be shown in Tables 5 and 6, respectively.

[0314] [Table 5]

[0315]

[0316] [Table 6]

[0317]

[0318] For example, as shown in Tables 5 and 6, the first processing order nested message may include a nested SEI message B1 whose target identification information is 00 and whose payload type information value is 100, and a nested SEI message C1 whose payload type information value is 150.

[0319] The second processing order nested message may include a nested SEI message B2 having target identification information of 10 and a payload type information value of 200, and a nested SEI message C2 having a payload type information value of 250. The encoded image information may be transmitted to a decoding device via a network.

[0320] For example, the second processing order superposition message may be dropped during coding by the encoding device or during transmission over a network. The decoding device may obtain image information including the first SEI processing order message, the second SEI processing order message, the first SEI message, the second SEI message, and the first processing order superposition message.

[0321] A first SEI processing order message may be encoded or processed. While the first SEI processing order message is being encoded or processed, it may be determined whether a constraint regarding the SEI processing order message is satisfied. For example, it may be determined whether a constraint regarding whether an SEI message acting as the ith SEI message in a processing chain specified by the first SEI processing order message is included in a processing order nesting message is satisfied with respect to wrapping flag information.

[0322] For example, it can be determined whether the constraints related to the first SEI processing order message are satisfied based on the wrapping flag information and the payload type information. Based on the fact that the value of the first wrapping flag information of the first SEI processing order message is 1 and the value of the payload type information is 100, the SEI message that acts as the first SEI message in the processing chain may be the nested SEI message B1. Based on the fact that the value of the second wrapping flag information of the first SEI processing order message is 0 and the value of the payload type information is 120, the SEI message that acts as the second SEI message in the processing chain may be the first SEI message A1 that is not included in the processing order nested message. Based on the fact that the value of the third wrapping flag information of the first SEI processing order message is 1 and the value of the payload type information is 150, the SEI message that acts as the third SEI message in the processing chain may be the nested SEI message C1.

[0323] In this way, it is determined that the constraints regarding the first SEI processing order message are satisfied, and the nested SEI message B1, the first SEI message A1, and the nested SEI message C1 can be encoded or processed.

[0324] A second SEI processing order message may be encoded or processed. While the second SEI processing order message is being encoded or processed, it may be determined whether a constraint on the SEI processing order message is satisfied. For example, it may be determined whether a constraint on whether an SEI message acting as the ith SEI message in the processing chain specified by the second SEI processing order message is included in a processing order nesting message is satisfied with respect to wrapping flag information.

[0325] For example, it can be determined whether the constraints related to the second SEI processing order message are satisfied based on the wrapping flag information and the payload type information. Based on the fact that the value of the first wrapping flag information of the second SEI processing order message is 1 and the value of the payload type information is 200, the SEI message that acts as the first SEI message in the processing chain can be searched for in the processing order nested message. Here, the nested SEI message B2 having the value of the payload type information of 200 does not exist in the image information.

[0326] At this time, even if the overlapping SEI message B2 does not exist in the image information, it is determined that the restriction requirements regarding the second SEI processing order message are satisfied, and the encoding device or decoding device can continue encoding or processing the SEI message without generating an error or stopping processing the SEI message. In other words, encoding or processing the second SEI processing order message can continue.

[0327] Based on the fact that the value of the second wrapping flag information of the second SEI processing order message is 0 and the value of the payload type information is 220, the SEI message that acts as the second SEI message in the processing chain may be the second SEI message A2 that is not included in the processing order nested message.

[0328] Based on the fact that the value of the third wrapping flag information of the second SEI processing order message is 1 and the value of the payload type information is 250, the SEI message that acts as the third SEI message in the processing chain can be searched in the processing order nested message. Here, the nested SEI message C2 whose payload type information has a value of 250 does not exist in the image information.

[0329] At this time, even if the overlapping SEI message C2 does not exist in the image information, it is determined that the restriction requirements regarding the second SEI processing order message are satisfied, and the encoding device or decoding device can continue encoding or processing the SEI message without generating an error or stopping processing the SEI message. In other words, encoding or processing the second SEI processing order message can continue.

[0330] As a result, it is determined that the restriction requirements regarding the SEI processing order message are satisfied, and the second SEI message A2, which is not included in the second processing order nested message, can be encoded or processed.

[0331] The SEI processing order message may include not only the payload type information of the nested SEI message included in the image information, but also the payload type information of the nested SEI message not included in the image information. Accordingly, the type information of the SEI message constituting the processing chain specified by the SEI processing order message may also include not only the payload type information of the nested SEI message included in the image information, but also the payload type information of the nested SEI message not included in the image information.

[0332] Additionally, for example, the second SEI message A2 may be dropped during coding by the encoding device or during transmission over a network. In an example, the decoding device may obtain image information including the first SEI processing order message, the second SEI processing order message, the first SEI message, the first processing order overlay message, and the second processing order overlay message.

[0333] A second SEI processing order message may be encoded or processed. While the second SEI processing order message is being encoded or processed, it may be determined whether a constraint on the SEI processing order message is satisfied. For example, it may be determined whether a constraint on whether an SEI message acting as the ith SEI message in the processing chain specified by the second SEI processing order message is included in a processing order nesting message is satisfied with respect to wrapping flag information.

[0334] For example, it can be determined whether the constraints related to the second SEI processing order message are satisfied based on the wrapping flag information and the payload type information. Based on the fact that the value of the first wrapping flag information of the second SEI processing order message is 1 and the value of the payload type information is 200, the SEI message that acts as the first SEI message in the processing chain can be the nested SEI message B2 whose payload type information has a value of 200.

[0335] Based on the fact that the value of the second wrapping flag information of the second SEI processing order message is 0 and the value of the payload type information is 220, the SEI message that acts as the second SEI message in the processing chain can be searched outside the processing order nested message. Here, the second SEI message A2 having the value of the payload type information of 220 does not exist in the image information.

[0336] At this time, even if the second SEI message A2 does not exist in the video information, it is determined that the restriction requirements regarding the second SEI processing order message are satisfied, and the encoding device or decoding device can continue encoding or processing the SEI message without generating an error or stopping processing the SEI message. In other words, encoding or processing of the second SEI processing order message can continue.

[0337] Based on the fact that the value of the third wrapping flag information of the second SEI processing order message is 1 and the value of the payload type information is 250, the SEI message that acts as the third SEI message in the processing chain may be a nested SEI message C2 whose payload type information has a value of 250.

[0338] As a result, it is determined that the constraints on the SEI processing order message are satisfied, and the nested SEI message B2 and the nested SEI message C2 can be encoded or processed.

[0339] The SEI processing order message may include not only payload type information of an SEI message other than a nested SEI message included in the image information, but also payload type information of an SEI message other than a nested SEI message not included in the image information. Accordingly, the type information of an SEI message other than an SEI message constituting a processing chain specified by the SEI processing order message may also include not only payload type information of an SEI message other than a nested SEI message included in the image information, but also payload type information of an SEI message other than a nested SEI message not included in the image information.

[0340] In one embodiment, flexibility is provided in the processing of SEI processing order messages and / or processing order nested messages, and errors occurring or interruptions in coding operations are reduced, thereby further improving coding efficiency and further increasing coding speed.

[0341] FIG. 7 is a diagram illustrating an example of a content streaming system to which an embodiment according to the present disclosure can be applied.

[0342] As illustrated in FIG. 7, 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.

[0343] The encoding server compresses content input from multimedia input devices such as smartphones, cameras, and camcorders into digital data, generates a bitstream, and transmits it to the streaming server. Alternatively, if multimedia input devices such as smartphones, cameras, and camcorders directly generate bitstreams, the encoding server may be omitted.

[0344] The above bitstream can 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 can temporarily store the bitstream during the process of transmitting or receiving the bitstream.

[0345] The streaming server transmits multimedia data to a user device based on a user request via a web server, and the web server can act as an intermediary to inform the user of available services. When a user requests a desired service from the web server, the web server transmits the request 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 may control commands / responses between each device within the content streaming system.

[0346] The streaming server can receive content from a media repository and / or 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 smooth streaming service, the streaming server can store the bitstream for a certain period of time.

[0347] Examples of the user devices may include mobile phones, smart phones, laptop computers, digital broadcasting terminals, personal digital assistants (PDAs), portable multimedia players (PMPs), navigation devices, slate PCs, tablet PCs, ultrabooks, wearable devices (e.g., smartwatches, smart glasses, HMDs), digital TVs, desktop computers, digital signage, etc.

[0348] Each server within the above content streaming system can be operated as a distributed server, in which case data received from each server can be processed in a distributed manner.

[0349] The scope of the present disclosure includes software or machine-executable instructions (e.g., operating systems, applications, firmware, programs, etc.) that cause operations according to the methods of various embodiments to be executed on a device or a computer, and a non-transitory computer-readable medium having such software or instructions stored thereon and executable on the device or computer.

[0350] Embodiments according to the present disclosure can be used to encode / decode images.

Claims

1. In a method for decoding video information, Obtaining image information including SEI (supplemental enhancement information) messages, an SEI processing order message indicating a processing order for a group of types of the SEI messages, and a processing order nested message including at least one nested SEI message within a processing chain specified by the SEI processing order message; Deriving a processing order for a type group of SEI messages based on the SEI processing order message, A method wherein the SEI processing order message includes wrapping flag information indicating whether an SEI message within a processing chain specified by the SEI processing order message is included in or not included in the processing order nested message.

2. In paragraph 1, Based on the value of the above wrapping flag information being 1, the SEI message within the processing chain specified by the SEI processing order message is included in the processing order overlap message, A method in which an SEI message within a processing chain specified by the SEI processing order message is not included in the processing order overlapping message based on the value of the above wrapping flag information being 0.

3. In paragraph 1, A method in which, based on the value of the wrapping flag information being 1, the target identification information of the processing order nested message is the same as the identification information of the SEI processing order message, the payload type of the at least one nested SEI message is the same as the payload type specified by the SEI processing order message, and the processing order of the at least one nested SEI message is the same as the processing order specified by the SEI processing order message.

4. In paragraph 1, A method in which an SEI message within a processing chain specified by the above SEI processing order message is allowed not to exist in the above image information.

5. In paragraph 1, A method in which an SEI message within a processing chain specified by the SEI processing order message includes at least one of an SEI message present in the image information or an SEI message not present in the image information.

6. In paragraph 1, The above SEI processing order message includes payload type information indicating the type of the SEI message, A method wherein the payload type information includes at least one of type information of an SEI message present in the image information or type information of an SEI message not present in the image information.

7. In paragraph 1, Based on the value of the above wrapping flag information being 1 and the SEI message within the processing chain specified by the SEI processing order message being present in the image information, the SEI message within the processing chain is included in the processing order overlap message, A method for indicating that an SEI message within the processing chain is not included in the processing order overlap message based on the value of the wrapping flag information being 0 and the presence of an SEI message within the processing chain specified by the SEI processing order message in the image information.

8. In a method for encoding image information, Generates a SEI (supplemental enhancement information) message; Determine the processing order for a group of types of the above SEI messages; Generate an SEI processing order message indicating the processing order based on the processing order; Generate a processing order nested message including at least one nested SEI message within the processing chain specified by the above SEI processing order message; Encoding image information including the SEI processing order message and the processing order overlapping message, A method wherein the SEI processing order message includes wrapping flag information indicating whether an SEI message within a processing chain specified by the SEI processing order message is included in or not included in the processing order nested message.

9. In paragraph 8, The value of the wrapping flag information is 1 based on the SEI message within the processing chain specified by the SEI processing order message being included in the processing order nesting message, A method in which the value of the wrapping flag information is 0 based on the SEI message within the processing chain specified by the SEI processing order message being not included in the processing order overlapping message.

10. In paragraph 8, A method in which, based on the value of the wrapping flag information being 1, the target identification information of the processing order nested message is the same as the identification information of the SEI processing order message, the payload type of the at least one nested SEI message is the same as the payload type specified by the SEI processing order message, and the processing order of the at least one nested SEI message is the same as the processing order specified by the SEI processing order message.

11. In paragraph 8, A method in which an SEI message within a processing chain specified by the above SEI processing order message is allowed not to exist in the above image information.

12. In paragraph 8, A method in which an SEI message within a processing chain specified by the SEI processing order message includes at least one of an SEI message present in the image information or an SEI message not present in the image information.

13. In paragraph 8, The above SEI processing order message includes payload type information indicating the type of the SEI message, A method wherein the payload type information includes at least one of type information of an SEI message present in the image information or type information of an SEI message not present in the image information.

14. In paragraph 8, Based on the value of the above wrapping flag information being 1 and the SEI message within the processing chain specified by the SEI processing order message being present in the image information, the SEI message within the processing chain is included in the processing order overlap message, A method of indicating that an SEI message within the processing chain is not included in the processing order overlap message based on the value of the wrapping flag information being 0 and the presence of an SEI message within the processing chain specified by the SEI processing order message in the image information.

15. In a method for transmitting data regarding image information, Generate a bitstream regarding the above image information; Including transmitting data including the above bitstream, The bitstream is generated based on generating an SEI (supplemental enhancement information) message, determining a processing order for a group of types of the SEI messages, generating an SEI processing order message indicating the processing order based on the processing order and a processing order nested message including at least one nested SEI message within a processing chain specified by the SEI processing order message, and generating a bitstream including image information including the SEI processing order message and the processing order nested message. A method wherein the SEI processing order message includes wrapping flag information indicating whether an SEI message within a processing chain specified by the SEI processing order message is included in or not included in the processing order nested message.

Images