Image encoding / decoding method and device, and recording medium on which bitstream is stored

Abstract

An image decoding method and device, according to the present disclosure, can receive a bitstream including an encoded video picture and reconstruct the encoded video picture included in the bitstream. Here, the bitstream can include a digitally signed content SEI message. The digitally signed content SEI message can include at least one from among a digitally signed content initialization SEI message, a digitally signed content selection SEI message, and a digitally signed content verification SEI message. The DSCS SEI message can include a substream identifier.

Description

Video encoding / decoding method and device, and a recording medium storing a bitstream

[0001] The present invention relates to a video encoding / decoding method and apparatus, and a recording medium storing a bitstream.

[0002] Recently, the demand for high-resolution, high-quality video, such as HD (High Definition) and UHD (Ultra High Definition) video, has been increasing across various application fields, and accordingly, high-efficiency video compression technologies are being discussed.

[0003] Various image compression technologies exist, such as inter-prediction technology that predicts pixel values ​​in the current picture from previous or subsequent pictures, intra-prediction technology that predicts pixel values ​​in the current picture using pixel information within the current picture, and entropy coding technology that assigns short codes to values ​​with high frequency and long codes to values ​​with low frequency; by utilizing these image compression technologies, image data can be effectively compressed for transmission or storage.

[0004] The present disclosure provides a method and apparatus for configuring a DSC SEI message.

[0005] The present disclosure provides a method and apparatus for signaling a DSC SEI message.

[0006] A video decoding method and apparatus according to the present disclosure receive a bitstream including an encoded video picture and can restore the encoded video picture included in the bitstream. The bitstream may include a digitally signed content (DSC) supplemental enhancement information (SEI) message. The DSC SEI message may include at least one of a digitally signed content initialization (DSCI) SEI message, a digitally signed content selection (DSCS) SEI message, or a digitally signed content verification (DSCV) SEI message. The DSCS SEI message may include a substream identifier. The DSC SEI message may be obtained from a network abstraction layer (NAL) unit of the bitstream.

[0007] In the image decoding method and apparatus according to the present disclosure, the DSCS SEI message can be applied to the currently encoded picture and all subsequent encoded pictures.

[0008] In the image decoding method and apparatus according to the present disclosure, the substream identifier may represent a verification substream to which related non-VCL NAL units have NAL unit type identifiers corresponding to the VCL NAL units of the encoded picture to which the current DSCS SEI message is applied, and values ​​within a predetermined list for the VCL NAL units.

[0009] In the image decoding method and apparatus according to the present disclosure, the DSCS SEI message may further include a DSCS cancellation flag. Here, the DSCS cancellation flag with a value of 1 indicates that the DSCS SEI message cancels the persistence of a previous DSCS SEI message in the output order, and the DSCS cancellation flag with a value of 0 may indicate that information regarding the DSCS follows.

[0010] In the image decoding method and apparatus according to the present disclosure, the DSCS SEI message may further include a DSCS persistence flag indicating the persistence of the DSCS SEI message.

[0011] In the image decoding method and apparatus according to the present disclosure, the persistence range of the DSCS SEI message can be determined by the semantics of the DSCS SEI message.

[0012] In the image decoding method and apparatus according to the present disclosure, the persistence range of the DSCS SEI message can be determined by the syntax of the DSCS SEI message.

[0013] In the image decoding method and apparatus according to the present disclosure, the persistence range of the DSCS SEI message may be a picture unit (PU) including the DSCS SEI message.

[0014] In the image decoding method and apparatus according to the present disclosure, the persistence range of the DSCS SEI message may be a picture associated with the DSCS SEI message.

[0015] In the image decoding method and apparatus according to the present disclosure, the DSCI SEI message may be selectively applied to either a picture or a subpicture.

[0016] A video encoding method and apparatus according to the present disclosure may receive a video picture to be encoded, encode the received video picture to generate video information regarding the video picture, generate a digitally signed content (DSC) supplemental enhancement information (SEI) message, and generate a bitstream including the video information and the DSC SEI message. The DSC SEI message may include at least one of a digitally signed content initialization (DSCI) SEI message, a digitally signed content selection (DSCS) SEI message, or a digitally signed content verification (DSCV) SEI message. The DSCS SEI message may include a substream identifier. The DSC SEI message may be encoded in a network abstraction layer (NAL) unit of the bitstream.

[0017] A computer-readable digital storage medium is provided that stores encoded video / image information that causes an image decoding method to be performed by a decoding device according to the present disclosure.

[0018] A computer-readable digital storage medium is provided that stores video / image information generated according to the image encoding method according to the present disclosure.

[0019] A method and apparatus for transmitting video / image information generated according to the image encoding method according to the present disclosure are provided.

[0020] A mechanism for verifying the signature of digital content can be provided through the configuration or signaling of a DSC SEI message according to the present disclosure.

[0021] According to the present disclosure, when a DSCS SEI message of the same content is repeatedly applied to two or more consecutive encoded pictures, the problem of duplicate DSCS SEI messages existing in all encoded pictures can be resolved.

[0022] FIG. 1 illustrates a video / image coding system according to the present disclosure.

[0023] FIG. 2 shows a schematic block diagram of an encoding device to which an embodiment of the present disclosure can be applied and to which encoding of a video / image signal is performed.

[0024] FIG. 3 shows a schematic block diagram of a decoding device to which an embodiment of the present disclosure can be applied and to which decoding of a video / image signal is performed.

[0025] FIG. 4 illustrates a method for restoring a video picture performed in a decoding device (300) according to the present disclosure.

[0026] FIG. 5 illustrates a schematic configuration of a decoding device (300) that performs a method for restoring a video picture according to the present disclosure.

[0027] FIG. 6 illustrates a method for generating a bitstream performed in an encoding device (200) according to the present disclosure.

[0028] FIG. 7 illustrates a schematic configuration of an encoding device (200) that performs a method for generating a bitstream according to the present disclosure.

[0029] FIG. 8 shows an example of a content streaming system to which embodiments of the present disclosure can be applied.

[0030] The present disclosure is susceptible to various modifications and may have various embodiments; specific embodiments are illustrated in the drawings and described in detail in the detailed description. However, this is not intended to limit the present disclosure to specific embodiments, and it should be understood that it includes all modifications, equivalents, and substitutions that fall within the spirit and scope of the present disclosure. Similar reference numerals have been used for similar components in the description of each drawing.

[0031] Terms such as "first," "second," etc., may be used to describe various components, but said components should not be limited by said terms. Such terms are used solely for the purpose of distinguishing one component from another. For example, without departing from the scope of the present disclosure, the first component may be named the second component, and similarly, the second component may be named the first component. The term "and / or" includes a combination of a plurality of related described items or any of a plurality of related described items.

[0032] When it is stated that one component is "connected" or "connected" to another component, it should be understood that while it may be directly connected or connected to that other component, there may also be other components in between. On the other hand, when it is stated that one component is "directly connected" or "directly connected" to another component, it should be understood that there are no other components in between.

[0033] The terms used in this application are used merely to describe specific embodiments and are not intended to limit the disclosure. The singular expression includes the plural expression unless the context clearly indicates otherwise. In this application, terms such as “comprising” or “having” are intended to specify the presence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, and should be understood as not precluding the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0034] The present disclosure relates to video / video coding. For example, the methods / embodiments disclosed herein may be applied to methods disclosed in the VVC (versatile video coding) standard. Additionally, the methods / embodiments disclosed herein may be applied to methods disclosed in the EVC (essential video coding) standard, AV1 (AOMedia Video 1) standard, AVS2 (2nd generation of audio video coding standard), or next-generation video / video coding standards (e.g., H.267 or H.268).

[0035] This specification presents various embodiments regarding video / image coding, and unless otherwise noted, said embodiments may be performed in combination with one another.

[0036] In this specification, "video" may refer to a set of images over time. "Picture" generally refers to a unit representing a single image of a specific time period, and "slice" or "tile" is a unit that constitutes a part of a picture in coding. A slice or tile may contain one or more coding tree units (CTUs). A picture may consist of one or more slices or tiles. A tile is a rectangular area composed of multiple CTUs within a specific tile column and a specific tile row of a picture. A tile column is a rectangular area of ​​CTUs having a height equal to the height of the picture and a width specified by the syntax requirements of the picture parameter set. A tile row is a rectangular area of ​​CTUs having a height specified by the picture parameter set and a width equal to the width of the picture. CTUs within a tile are arranged continuously according to the CTU raster scan, whereas tiles within a picture may be arranged continuously according to the tile's raster scan. A single slice may include an integer number of complete tiles or an integer number of consecutive complete CTU rows within a tile of a picture that can be exclusively contained in a single NAL unit. Meanwhile, a single picture may be divided into two or more subpictures. A subpicture may be a rectangular area of ​​one or more slices within a picture.

[0037] A pixel, or pel, can refer to the smallest unit that constitutes a picture (or image). Additionally, the term 'sample' may be used as a counterpart to pixel. A sample generally represents a pixel or its value, and it may represent only the pixel / pixel value of the luminance (luma) component or only the pixel / pixel value of the chroma component.

[0038] A unit may represent a basic unit of image processing. A unit may include at least one of a specific area of ​​a picture and information related to that area. A unit may include one luminance block and two chroma (e.g., cb, cr) blocks. Depending on the case, the term unit may be used interchangeably with terms such as block or area. In general, an MxN block may include samples (or sample arrays) or a set (or array) of transform coefficients consisting of M columns and N rows.

[0039] In this specification, "A or B" may mean "only A," "only B," or "both A and B." Alternatively, in this specification, "A or B" may be interpreted as "A and / or B." For example, in this specification, "A, B or C" may mean "only A," "only B," "only C," or "any combination of A, B and C."

[0040] A slash ( / ) or a comma used in this specification may mean "and / or." For example, "A / B" may mean "A and / or B." Accordingly, "A / B" may mean "only A," "only B," or "both A and B." For example, "A, B, C" may mean "A, B or C."

[0041] In this specification, "at least one of A and B" may mean "only A," "only B," or "both A and B." Additionally, in this specification, the expressions "at least one of A or B" or "at least one of A and / or B" may be interpreted as synonymous with "at least one of A and B."

[0042] Additionally, in this specification, "at least one of A, B and C" may mean "only A," "only B," "only C," or "any combination of A, B and C." Also, "at least one of A, B or C" or "at least one of A, B and / or C" may mean "at least one of A, B and C."

[0043] Additionally, parentheses used in this specification may mean "for example." Specifically, where indicated as "prediction (intra-prediction)," "intra-prediction" may be proposed as an example of "prediction." In other words, "prediction" in this specification is not limited to "intra-prediction," and "intra-prediction" may be proposed as an example of "prediction." Furthermore, even where indicated as "prediction (i.e., intra-prediction)," "intra-prediction" may be proposed as an example of "prediction."

[0044] Technical features described individually within a single drawing in this specification may be implemented individually or simultaneously.

[0045] FIG. 1 illustrates a video / image coding system according to the present disclosure.

[0046] Referring to FIG. 1, the video / image coding system may include a first device (source device) and a second device (receiving device).

[0047] A source device can transmit encoded video / image information or data in the form of a file or streaming to a receiving device via a digital storage medium or a network. The source device may include a video source, an encoding device, and a transmission unit. The receiving device may include a receiver, a decoding device, and a renderer. The encoding device may be referred to as a video / image encoding device, and the decoding device may be referred to as a video / image decoding device. A transmitter may be included in the encoding device. A receiver may be included in the decoding device. The renderer may include a display unit, and the display unit may be composed of a separate device or an external component.

[0048] A video source may acquire video / images through processes such as video / image capture, synthesis, or generation. The video source may include a video / image capture device and / or a video / image generation device. A video / image capture device may include one or more cameras, a video / image archive containing previously captured video / images, etc. A video / image generation device may include a computer, a tablet, a smartphone, etc., and may generate video / images (electronically). 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 in which related data is generated.

[0049] The encoding device can encode input video / images. The encoding device can perform a series of procedures, such as prediction, transformation, and quantization, for compression and coding efficiency. The encoded data (encoded video / image information) can be output in the form of a bitstream.

[0050] 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 in the form of a file or streaming via a digital storage medium or a network. The digital storage medium may include various storage media such as USB, SD, CD, DVD, Blu-ray, HDD, SSD, etc. The transmission unit may include elements for creating a media file through a predetermined file format and elements for transmission via a broadcasting / communication network. The receiving unit can receive / extract the bitstream and transmit it to a decoding device.

[0051] The decoding device can decode video / images by performing a series of procedures such as inverse quantization, inverse transform, and prediction corresponding to the operation of the encoding device.

[0052] The renderer can render the decoded video / image. The rendered video / image can be displayed through the display unit.

[0053] FIG. 2 shows a schematic block diagram of an encoding device to which an embodiment of the present disclosure can be applied and to which encoding of a video / image signal is performed.

[0054] Referring to FIG. 2, the encoding device (200) may be configured to include an image partitioner (210), a predictor (220), a residual processor (230), an entropy encoder (240), an adder (250), a filter (260), and a memory (270). The predictor (220) may include an inter-predictor (221) and an intra-predictor (222). The residual processor (230) may include a transformer (232), a quantizer (233), a dequantizer (234), and an inverse transformer (235). The residual processor (230) may further include a subtractor (231). The addition unit (250) may be referred to as a reconstructor or a reconstructed block generator. The above-described image segmentation unit (210), prediction unit (220), residual processing unit (230), entropy encoding unit (240), addition unit (250), and filtering unit (260) may be configured by one or more hardware components (e.g., an encoding device chipset or processor) according to the embodiment. Additionally, the memory (270) may include a decoded picture buffer (DPB) and may be configured by a digital storage medium. The hardware component may further include the memory (270) as an internal / external component.

[0055] The image segmentation unit (210) can divide an input image (or picture, frame) input to an encoding device (200) into one or more processing units. For example, the processing unit may be called a coding unit (CU). In this case, the coding unit may be recursively divided from a coding tree unit (CTU) or a largest coding unit (LCU) according to a QTBTTT (Quad-tree binary-tree ternary-tree) structure.

[0056] For example, a single coding unit may be divided into multiple coding units with a deeper depth based on a quad tree structure, a binary tree structure, and / or a terrestrial structure. In this case, for example, the quad tree structure may be applied first and the binary tree structure and / or terrestrial structure may be applied later. Alternatively, the binary tree structure may be applied before the quad tree structure. A coding procedure according to the present specification may be performed based on a final coding unit that is no longer divided. In this case, based on coding efficiency according to image characteristics, the maximum coding unit may be used directly as the final coding unit, or, if necessary, the coding unit may be recursively divided into coding units of a lower depth so that a coding unit of the optimal size may be used as the final coding unit. Here, the term "coding procedure" may include procedures such as prediction, transformation, and restoration described below.

[0057] As another example, the processing unit may further include a Prediction Unit (PU) or a Transform Unit (TU). In this case, the Prediction Unit and the Transform Unit may each be divided or partitioned from the aforementioned final coding unit. The Prediction Unit may be a unit for sample prediction, and the Transform Unit may be a unit for deriving transformation coefficients and / or a unit for deriving a residual signal from transformation coefficients.

[0058] The term "unit" may be used interchangeably with terms such as "block" or "area" depending on the context. In general, an MxN block may represent a set of samples or transform coefficients consisting of M columns and N rows. A sample can generally represent a pixel or a pixel value, and may represent only the pixel / pixel value of the luminance component or only the pixel / pixel value of the chroma component. A sample may be used to refer to a single picture (or image) as a term corresponding to a pixel or pel.

[0059] The encoding device (200) can generate a residual signal (residual block, residual sample array) by subtracting a prediction signal (prediction 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, the unit that subtracts the prediction signal (prediction block, prediction sample array) from the input video signal (original block, original sample array) within the encoding device (200) may be called a subtraction unit (231).

[0060] The prediction unit (220) performs a prediction for a block to be processed (hereinafter referred to as the current block) and can generate a predicted block containing prediction samples for the current block. The prediction unit (220) can determine whether intra prediction is applied or inter prediction is applied at the current block or CU level. The prediction unit (220) can generate various information regarding the prediction, such as prediction mode information, as described below in the description of each prediction mode, and transmit it to the entropy encoding unit (240). The information regarding the prediction can be encoded by the entropy encoding unit (240) and output in the form of a bitstream.

[0061] The intra prediction unit (222) can predict the current block by referring to samples within the current picture. The referenced samples may be located near the current block or at a certain distance from the current block depending on the prediction mode. In intra prediction, the prediction modes may include one or more non-directional modes and multiple directional modes. The non-directional mode may include at least one DC mode or a planar mode. The directional mode may include 33 directional modes or 65 directional modes depending on the degree of fineness of the prediction direction. However, this is merely an example, and depending on the settings, more or fewer directional modes may be used. The intra prediction unit (222) may determine the prediction mode applied to the current block by using the prediction mode applied to the surrounding blocks.

[0062] The inter prediction unit (221) can derive a prediction block for the current block based on a reference block (reference sample array) specified by a motion vector on a reference picture. At this time, to reduce the amount of motion information transmitted in the inter prediction mode, motion information can be predicted in blocks, sub-blocks, or samples based on the correlation of motion information between neighboring blocks and the current block. The motion information may include a motion vector and a reference picture index. The motion information may further include inter prediction direction information (L0 prediction, L1 prediction, Bi prediction, etc.). In the case of inter prediction, neighboring blocks may include spatial neighboring blocks existing within the current picture and temporal neighboring blocks existing in the reference picture. The reference picture containing the reference blocks and the reference picture containing the temporal neighboring blocks may be the same or different. The above temporal surrounding blocks may be referred to by names such as collocated reference block, collocated CU (colCU), etc., and the reference picture containing the above temporal surrounding blocks may be referred to as a collocated picture (colPic). For example, the inter prediction unit (221) may construct a list of motion information candidates based on surrounding blocks and generate information indicating which candidate is used to derive the motion vector and / or reference picture index of the current block. Inter prediction may be performed based on various prediction modes, for example, in the case of skip mode and merge mode, the inter prediction unit (221) may use the motion information of surrounding blocks as motion information of the current block. In the case of skip mode, unlike merge mode, a residual signal may not be transmitted.In the motion vector prediction (MVP) mode, the motion vectors of surrounding blocks are used as motion vector predictors, and the motion vector of the current block can be indicated by signaling the motion vector difference.

[0063] The prediction unit (220) can generate a prediction signal based on various prediction methods described below. For example, the prediction unit may apply intra prediction or inter prediction for prediction of a single block, and may also apply intra prediction and inter prediction simultaneously. This may be called a combined inter and intra prediction (CIIP) mode. Additionally, the prediction unit may 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 may be used for content video / video coding, such as in screen content coding (SCC) for games. IBC basically performs prediction within the current picture, but it may be performed similarly to inter prediction in that it derives a reference block within the current picture. That is, IBC may utilize at least one of the inter prediction techniques described in this specification. The palette mode can be viewed as an example of intra coding or intra prediction. When the palette mode is applied, sample values ​​within the picture can be signaled based on information regarding the palette table and palette index. The prediction signal generated through the prediction unit (220) can be used to generate a restoration signal or to generate a residual signal.

[0064] The transformation unit (232) can generate transform coefficients by applying a transformation technique to a residual signal. For example, the transformation technique may include at least one of a Discrete Cosine Transform (DCT), a Discrete Sine Transform (DST), a Karhunen-Loeve Transform (KLT), a Graph-Based Transform (GBT), or a Conditionally Non-linear Transform (CNT). Here, GBT refers to a transformation obtained from a graph when the relationship information between pixels is represented as a graph. CNT refers to a transformation obtained based on a prediction signal generated using all previously restored pixels. Additionally, the transformation process may be applied to a pixel block of the same size in a square, or to a block of variable size that is not square.

[0065] The quantization unit (233) quantizes the transformation coefficients and transmits them to the entropy encoding unit (240), and the entropy encoding unit (240) can encode the quantized signal (information regarding the quantized transformation coefficients) and output it as a bitstream. The information regarding the quantized transformation coefficients may be called residual information. The quantization unit (233) can rearrange the block-shaped quantized transformation coefficients into a one-dimensional vector form based on the coefficient scan order, and can also generate information regarding the quantized transformation coefficients based on the one-dimensional vector-shaped quantized transformation coefficients.

[0066] The entropy encoding unit (240) can perform various encoding methods such as exponential Golomb, CAVLC (context-adaptive variable length coding), CABAC (context-adaptive binary arithmetic coding), etc. The entropy encoding unit (240) may encode information required for video / image restoration (e.g., values ​​of syntax elements, etc.) together or separately, in addition to quantized transform coefficients.

[0067] Encoded information (e.g., encoded video / image information) may be transmitted or stored in the form of a bitstream at the level of a Network Abstraction Layer (NAL) unit. The video / image information may further include information regarding various parameter sets, such as an Adaptation Parameter Set (APS), a Picture Parameter Set (PPS), a Sequence Parameter Set (SPS), or a Video Parameter Set (VPS). Additionally, the video / image information may further include general constraint information. In this specification, information and / or syntax elements transmitted / signaled from an encoding device to a decoding device may be included in the video / image information. The video / image information may be encoded through the encoding procedure described above and included in the bitstream. The bitstream may be transmitted over a network or stored on 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) that transmits the signal output from the entropy encoding unit (240) and / or a storage unit (not shown) that stores it may be configured as internal / external elements of the encoding device (200), or the transmission unit may be included in the entropy encoding unit (240).

[0068] Quantized transformation coefficients output from the quantization unit (233) can be used to generate a prediction signal. For example, a residual signal (residual block or residual samples) can be restored by applying inverse quantization and inverse transformation to the quantized transformation coefficients through the inverse quantization unit (234) and the inverse transformation unit (235). An adder (250) can generate a reconstructed signal (reconstructed picture, reconstructed block, reconstructed sample array) by adding the restored residual signal to the prediction signal output from the inter-prediction unit (221) or the intra-prediction unit (222). In cases where there is no residual for the block to be processed, such as when a skip mode is applied, the predicted block can be used as the reconstructed block. The adder (250) may be called a reconstruction unit or a reconstruction 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 filtering as described below. Meanwhile, LMCS (luma mapping with chroma scaling) may be applied during the picture encoding and / or restoration process.

[0069] The filtering unit (260) can improve subjective / objective image quality by applying filtering to the restored signal. For example, the filtering unit (260) can generate a modified restored picture by applying various filtering methods to the restored picture, and can store the modified restored picture in memory (270), specifically in the DPB of memory (270). The various filtering methods may include 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). The information regarding filtering can be encoded in the entropy encoding unit (240) and output in the form of a bitstream.

[0070] 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 can avoid prediction mismatches between the encoding device (200) and the decoding device, and can also improve encoding efficiency.

[0071] The DPB of the memory (270) can store the modified restored picture to be used as a reference picture in the inter-prediction unit (221). The memory (270) can store motion information of blocks from which motion information is derived (or encoded) within the current picture and / or motion information of blocks within the picture that have already been restored. The stored motion information can be transmitted to the inter-prediction unit (221) to be used as motion information of spatially surrounding blocks or motion information of temporally surrounding blocks. The memory (270) can store restoration samples of the blocks restored within the current picture and transmit them to the intra-prediction unit (222).

[0072] FIG. 3 shows a schematic block diagram of a decoding device to which an embodiment of the present disclosure can be applied and to which decoding of a video / image signal is performed.

[0073] Referring to FIG. 3, the decoding device (300) may be configured to include an entropy decoder (310), a residual processor (320), a predictor (330), an adder (340), a filter (350), and a memory (360). The predictor (330) may include an inter-predictor (332) and an intra-predictor (331). The residual processor (320) may include a dequantizer (321) and an inverse transformer (321).

[0074] The aforementioned entropy decoding unit (310), residual processing unit (320), prediction unit (330), addition unit (340), and filtering unit (350) may be configured by a single hardware component (e.g., a decoding device chipset or processor) according to an embodiment. Additionally, the memory (360) may include a DPB (decoded picture buffer) and may be configured by a digital storage medium. The hardware component may further include the memory (360) as an internal / external component.

[0075] When a bitstream containing video / image information is input, the decoding device (300) can restore the image in correspondence with the process in which the video / image information is processed by the encoding device of FIG. 2. For example, the decoding device (300) can derive units / blocks based on block division information obtained from the bitstream. The decoding device (300) can perform decoding using a processing unit applied by the encoding device. Accordingly, the processing unit for decoding may be a coding unit, and the coding unit may be divided from a coding tree unit or a maximum coding unit according to a quad tree structure, a binary tree structure, and / or a binary tree structure. One or more conversion units may be derived from the coding unit. And, the restored image signal decoded and output through the decoding device (300) can be played back through a playback device.

[0076] The decoding device (300) can receive a signal output from the encoding device of FIG. 2 in the form of a bitstream, and the received signal can be decoded through an entropy decoding unit (310). For example, the entropy decoding unit (310) can parse the bitstream to derive information (e.g., video / image information) necessary for image restoration (or picture restoration). The video / image information may further include information regarding various parameter sets, such as an adaptation parameter set (APS), a picture parameter set (PPS), a sequence parameter set (SPS), or a video parameter set (VPS). Additionally, the video / image information may further include general constraint information. The decoding device can decode the picture based on information regarding the parameter sets and / or the general constraint information. The signaling / receiving information and / or syntax elements described below in this specification may be decoded through the decoding procedure and obtained from the bitstream. For example, the entropy decoding unit (310) can decode information within the bitstream based on coding methods such as exponential chord coding, CAVLC, or CABAC, and output the values ​​of syntax elements required for image restoration and the quantized values ​​of transformation coefficients regarding residuals. More specifically, the CABAC entropy decoding method can receive a bin corresponding to each syntax element in the bitstream, determine a context model using information on the syntax element to be decoded and decoding information of surrounding and decoding target blocks or information on symbols / bins decoded in the previous step, predict the probability of occurrence of the bin according to the determined context model, and perform arithmetic decoding of the bin to generate a symbol corresponding to the value of each syntax element.At this time, the CABAC entropy decoding method can update the context model using the decoded symbol / bin information for the context model of the next symbol / bin after determining the context model. Among the information decoded in the entropy decoding unit (310), information regarding prediction is provided to the prediction unit (inter prediction unit (332) and intra prediction unit (331)), and the residual value for which entropy decoding was performed in the entropy decoding unit (310), i.e., quantized transformation coefficients and related parameter information, can be input to the residual processing unit (320). The residual processing unit (320) can derive residual signals (residual blocks, residual samples, residual sample array). Additionally, among the information decoded in the entropy decoding unit (310), information regarding filtering can be provided to the filtering unit (350). Meanwhile, a receiving unit (not shown) that receives a signal output from an encoding device may be further configured as an internal / external element of the decoding device (300), or the receiving unit may be a component of the entropy decoding unit (310).

[0077] Meanwhile, the decoding device according to the present specification may be called a video / image / picture decoding device, and the decoding device may be divided into an information decoding device (video / image / picture information decoding device) and a sample decoding device (video / image / picture sample decoding device). The information decoding device may include the entropy decoding unit (310), and the sample decoding device may include at least one of the inverse quantization unit (321), inverse transform unit (322), adder (340), filtering unit (350), memory (360), inter prediction unit (332), and intra prediction unit (331).

[0078] In the inverse quantization unit (321), the quantized transformation coefficients can be inversely quantized to output transformation coefficients. The inverse quantization unit (321) can rearrange the quantized transformation coefficients into a two-dimensional block form. In this case, the rearrangement can be performed based on the coefficient scan order performed by the encoding device. The inverse quantization unit (321) can perform inverse quantization on the quantized transformation coefficients using quantization parameters (e.g., quantization step size information) and obtain transformation coefficients.

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

[0080] The prediction unit (320) can perform a prediction for the current block and generate a predicted block containing prediction samples for the current block. The prediction unit (320) can determine whether an intra prediction or an inter prediction is applied to the current block based on information regarding the prediction output from the entropy decoding unit (310), and can determine a specific intra / inter prediction mode.

[0081] The prediction unit (320) can generate a prediction signal based on various prediction methods described below. For example, the prediction unit (320) may apply intra prediction or inter prediction for prediction of a single block, and may also apply intra prediction and inter prediction simultaneously. This may be called a combined inter and intra prediction (CIIP) mode. Additionally, the prediction unit may 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 may be used for content video / video coding, such as in games, such as SCC (screen content coding). IBC basically performs prediction within the current picture, but it may be performed similarly to inter prediction in that it derives a reference block within the current picture. That is, IBC may utilize at least one of the inter prediction techniques described in this specification. The palette mode can be viewed as an example of intra coding or intra prediction. When palette mode is applied, information regarding the palette table and palette index can be included in the above video / image information and signaled.

[0082] The intra prediction unit (331) 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 according to the prediction mode, or may be located at a certain distance from the current block. In intra prediction, the prediction modes may include one or more non-directional modes and a plurality of directional modes. The intra prediction unit (331) may determine the prediction mode applied to the current block by using the prediction mode applied to the neighboring blocks.

[0083] The inter prediction unit (332) can derive a prediction block for the current block based on a reference block (reference sample array) specified by a motion vector on a reference picture. At this time, to reduce the amount of motion information transmitted in the inter prediction mode, motion information can be predicted in blocks, sub-blocks, or samples based on the correlation of motion information between neighboring blocks and the current block. The motion information may include a motion vector and a reference picture index. The motion information may further include inter prediction direction information (L0 prediction, L1 prediction, Bi prediction, etc.). In the case of inter prediction, neighboring blocks may include spatial neighboring blocks existing within the current picture and temporal neighboring blocks existing in the reference picture. For example, the inter prediction unit (332) may construct a motion information candidate list based on 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, and information regarding the prediction may include information indicating the inter-prediction mode for the current block.

[0084] The adder (340) can generate a restoration signal (restoration picture, restoration block, restoration sample array) by adding the acquired residual signal to the prediction signal (prediction block, prediction sample array) output from the prediction unit (including the inter prediction unit (332) and / or the intra prediction unit (331)). In cases where there is no residual for the block to be processed, such as when a skip mode is applied, the prediction block can be used as the restoration block.

[0085] The addition unit (340) may be called a restoration unit or a restoration block generation unit. The generated restoration signal may be used for intra-predicting the next block to be processed within the current picture, may be output after filtering as described below, or may be used for inter-predicting the next picture. Meanwhile, LMCS (luma mapping with chroma scaling) may be applied during the picture decoding process.

[0086] The filtering unit (350) can improve subjective / objective image quality by applying filtering to the restored signal. For example, the filtering unit (350) can generate a modified restored picture by applying various filtering methods to the restored picture, and can transmit the modified restored picture to memory (360), specifically to the DPB of memory (360). The various filtering methods may include deblocking filtering, sample adaptive offset, adaptive loop filter, bilateral filter, etc.

[0087] The (modified) restored picture stored in the DPB of the memory (360) can be used as a reference picture in the inter prediction unit (332). The memory (360) can store motion information of blocks from which motion information within the current picture has been derived (or decoded) and / or motion information of blocks within the picture that have already been restored. The stored motion information can be transmitted to the inter prediction unit (332) to be used as motion information of spatially surrounding blocks or motion information of temporally surrounding blocks. The memory (360) can store restoration samples of blocks restored within the current picture and transmit them to the intra prediction unit (331).

[0088] In this specification, the embodiments described in the filtering unit (260), inter prediction unit (221), and intra prediction unit (222) of the encoding device (200) may be applied to the filtering unit (350), inter prediction unit (332), and intra prediction unit (331) of the decoding device (300) in the same or corresponding manner.

[0089] FIG. 4 illustrates a method for restoring a video picture performed in a decoding device (300) according to the present disclosure.

[0090] A bitstream containing an encoded video picture can be received (S400).

[0091] The encoded video picture of the bitstream can be restored (S410).

[0092] Video information regarding an encoded video picture can be extracted from the bitstream. Based on the extracted video information, the encoded video picture can be restored.

[0093] The bitstream may include a digitally signed content (DSC) supplemental enhancement information (SEI) message. The DSC SEI message may include at least one of a digitally signed content initialization (DSCI) SEI message, a digitally signed content selection (DSCS) SEI message, or a digitally signed content verification (DSCV) SEI message. This may provide a mechanism for verifying that a content provider, who identifies themselves through a digital certificate referenced in the digitally signed content initialization SEI message, has generated the corresponding encoded image.

[0094] This SEI message may provide information about the security hash algorithm used to calculate the message digest. The message digest, along with the digital signature present in the digitally signed content verification SEI message, may be used to verify the authenticity of non-VCL NAL units having NAL unit type identifiers corresponding to the values ​​contained in the list (nonVclDigitallySignedNalUnitsList) and VCL NAL units contained in the encoded video sequence. NonVclDigitallySignedNalUnitsList may be a list composed of non-VCL NAL unit type identifiers. For example, nonVclDigitallySignedNalUnitsList may be composed of NAL unit types having nal_unit_type with values ​​15, 16, 17, 18, and 19.

[0095] This SEI message may provide information about the digital signature algorithm used and the content provider's public key. The DSCI SEI message may provide the content provider's public key by providing a URI that identifies a trust record containing the content provider's certificate, as specified in ISO / IEC 21617-1, or by providing a URI that directly identifies the certificate.

[0096] If a DSCI SEI message exists in any AU (access unit) within a CVS (coded video sequence), a DSCI SEI message must exist for all IDR, CRA, and GDR PUs of that CVS.

[0097] If a DSCI SEI message exists in any AU within CVS, it must precede all non-VCL NAL units with NAL unit type identifiers corresponding to the values ​​in nonVclDigitallySignedNalUnitsList and all VCL NAL units in that AU.

[0098] DSCI SEI messages may be applied to the currently encoded picture and all subsequent encoded pictures until one or more of the following conditions become true.

[0099] - The bitstream ends.

[0100] - A new CVS begins.

[0101] - A new DSCI SEI message is received.

[0102] If a DSCI SEI message exists in an AU within CVS, a DSCV SEI message must exist for each substream to which a NAL unit is assigned. A DSCV SEI message must exist in the bitstream before one or more of the following conditions become true.

[0103] - The bitstream ends.

[0104] - A new CVS begins.

[0105] - A new DSCI SEI message is received.

[0106] Table 1 is an example of a DSCI SEI message according to the present disclosure.

[0107] digitally_signed_content_initialization( payloadSize ) {Descriptordsci_hash_method_typeu(8)dsci_key_source_urist(v)dsci_num_verification_substreams_minus1ue(v)dsci_key_retrieval_mode_idcue(v)if( dsci_key_retrieval_mode_idc = = 1){dsci_use_key_register_idx_flagu(1)if( dsci_use_key_register_idx_flag )dsci_key_register_idxue(v)}dsci_content_uuid_present_flagu(1)if( dsci_content_uuid_present_flag)dsci_content_uuidu(128)}

[0108] DSCI SEI messages may include hash method type information (dsci_hash_method_type).

[0109] dsci_hash_method_type may represent a secure hash algorithm used to calculate a message digest for non-VCL NAL units with NAL unit type identifiers corresponding to the values ​​included in nonVclDigitallySignedNalUnitsList and a subset of VCL NAL units of an encoded video sequence.

[0110] Based on the above message digest and digital signature, the decoding device can verify that the corresponding encoded video was generated by the content originator. The digital signature may be present in the DSCV SEI message. The content originator may be indicated by a syntax element (e.g., at least one of dsci_key_source_uri, dsci_use_key_register_idx_flag, or dsci_key_register_idx). The above syntax elements will be described later.

[0111] The supported values ​​for dsci_hash_method_type, the block size used for message digest calculation, and the size of the calculated message digest can be defined as shown in Table 2 below.

[0112] dsci_hash_method_typeHash methodBlock size (bits)Message digest size (bits)0SHA-15121601SHA-2245122242SHA-2565122563SHA-38410243844SHA-51210245125SHA-512 / 22410242246SHA-512 / 2561024256

[0113] The secure hash algorithms listed in Table 2 are specified in the "Secure Hash Standard" of NIST FIPS PUB 180-4.

[0114] DSCI SEI messages may include key source URI information (dsci_key_source_uri).

[0115] dsci_key_source_uri may contain a uniform resource identifier (URI) that follows the syntax and semantics specified in IETF Internet Standard 66.

[0116] If dsci_key_retrieval_mode_idc, described below, is 0, dsci_key_source_uri can specify a trust record as defined in ISO / IEC 21617-1. If dsci_key_retrieval_mode_idc is 1, the following may apply:

[0117] - If dsci_use_key_register_idx_flag is 0, the URI can identify a content provider's certificate that can be used to verify signatures present in subsequent DSCV SEI messages.

[0118] - If dsci_use_key_register_idx_flag is 1, the URI can identify a certificate register and the certificate of the content provider indicated by dsci_key_register_idx. The certificate can be used to verify signatures present in subsequent DSCV SEI messages.

[0119] A DSCI SEI message may include substream count information (dsci_num_verification_substreams_minus1). dsci_num_verification_substreams_minus1 may represent the number of substreams where a signature may exist in subsequent DSCV SEI messages after the message digest is calculated. For example, the number of substreams (NumVerificationSubstream) can be derived as shown in Equation 1 below.

[0120] [Mathematical Formula 1]

[0121] NumVerificationSubstream = dsci_num_verification_substreams_minus1 + 1

[0122] dsci_num_verification_substreams_minus1 may be encoded as a descriptor of ue(v). That is, dsci_num_verification_substreams_minus1 may be a variable-length syntax element that encodes an unsigned integer in Exp-Golomb code.

[0123] DSCI SEI messages may include a key retrieval mode indicator (dsci_key_retrieval_mode_idc).

[0124] If dsci_key_retrieval_mode_idc is 0, it may indicate that the URI contained in dsci_key_source_uri specifies a trust record as defined in ISO / IEC 21617-1. If dsci_key_retrieval_mode_idc is 1, it may indicate that the URI contained in dsci_key_source_uri and dsci_key_register_idx specify a certificate.

[0125] The value of dsci_key_retrieval_mode_idc must be in the range from 0 to 1. The decoding device must accept a different value of dsci_key_retrieval_mode_idc, but in such case, ignore the contents of DSCI SEI messages, related DSCS SEI messages, and related DSCV SEI messages.

[0126] DSCI SEI messages may include a register index flag (dsci_use_key_register_idx_flag).

[0127] If dsci_use_key_register_idx_flag is 1, it may indicate that the URI included in dsci_key_source_uri specifies a certificate register. Additionally, if dsci_use_key_register_idx_flag is 1, it may indicate that dsci_key_register_idx exists in a DSCI SEI message. If dsci_use_key_register_idx_flag is 0, it may indicate that the URI included in dsci_key_source_uri specifies a certificate. Additionally, if dsci_use_key_register_idx_flag is 0, it may indicate that dsci_key_register_idx does not exist in a DSCI SEI message.

[0128] If dsci_key_retrieval_mode_idc is 0, the media asset for which the last trust manifest within the trust record specified in ISO / IEC 21617-1 provides content binding is a DSCI SEI message. The following constraints may apply to the trust record specified in ISO / IEC 21617-1 identified by dsci_key_source_uri:

[0129] - The last trust manifest of a trust record specified in ISO / IEC 21617-1 must contain a single hard binding data hash assertion with the label c2pa.hash.data.

[0130] - The schema of the data hash assertion is defined by the data-hash-map rule included in the CDDL definition in Table 3 below.

[0131] ; The data structure used to store the cryptographic hash of some or all of the asset's data; and additional information required to compute the hash.data-hash-map = {? "exclusions": [1* EXCLUSION_RANGE-map], ; Ranges have monotonically increasing `start` values, and no two ranges may overlap.? "alg":tstr .size (1..max-tstr-length), ; A string identifying the cryptographic hash algorithm used to compute the hash in this assertion."hash": bstr, ; byte string of the hash value"pad": bstr, ; zero-filled byte string used for filling up space? "pad2": bstr, ; optional zero-filled byte string used for filling up space? "name": tstr .size (1..max-tstr-length), ; (optional) a human-readable description of what this hash cover? "url": uri, ; Unused and deprecated.}EXCLUSION_RANGE-map = {"start": int, ; Starting byte of the range"length": int, ; Number of bytes of data to exclude}

[0132] - The exclusion range specified in the data hash assertion, which specifies the data to be excluded when calculating the hash value in the DSCI SEI message, must match the dsci_key_source_uri bytes in the DSCI SEI message.

[0133] dsci_use_key_register_idx_flag can be adaptively signaled based on dsci_key_retrieval_mode_idc. For example, dsci_use_key_register_idx_flag can be signaled based on the value of dsci_key_retrieval_mode_idc being 1. dsci_use_key_register_idx_flag may not be signaled based on the value of dsci_key_retrieval_mode_idc being 0.

[0134] DSCI SEI messages may include register index information (dsci_key_register_idx).

[0135] dsci_key_register_idx may contain an index that identifies the content provider's certificate within the certificate register indicated by dsci_key_source_uri. The content provider's certificate may be used to verify signatures present in subsequent DSCV SEI messages.

[0136] A certificate specified by at least one of dsci_key_retrieval_mode_idc, dsci_use_key_register_idx_flag, dsci_key_source_uri, or dsci_key_register_idx is required to specify at least one of a digital signature method or a content provider's public key.

[0137] dsci_key_register_idx can be adaptively signaled based on dsci_use_key_register_idx_flag. For example, dsci_key_register_idx can be signaled based on the value of dsci_use_key_register_idx_flag being 1. dsci_key_register_idx may not be signaled based on the value of dsci_use_key_register_idx_flag being 0.

[0138] dsci_key_register_idx can be adaptively signaled based on dsci_key_retrieval_mode_idc. For example, dsci_key_register_idx can be signaled based on the value of dsci_key_retrieval_mode_idc being 1. dsci_key_register_idx may not be signaled based on the value of dsci_key_retrieval_mode_idc being 0.

[0139] DSCI SEI messages may include a UUID present flag (dsci_content_uuid_present_flag).

[0140] If dsci_content_uuid_present_flag is 1, it may indicate that dsci_content_uuid exists. If dsci_content_uuid_present_flag is 0, it may indicate that dsci_content_uuid does not exist.

[0141] If dsci_key_retrieval_mode_idc is 0, dsci_content_uuid_present_flag may be restricted to a value of 1.

[0142] DSCI SEI messages can include content UUID information (dsci_content_uuid).

[0143] dsci_content_uuid may represent an identifier for video content. dsci_content_uuid must have a value specified as a UUID according to the procedure of Appendix A of ISO / IEC 11578:1996.

[0144] If a DSCI SEI message exists within the AU, the calculation of NumVerificationSubstream message digests may be initialized according to the NIST FIPS PUB 180-4 specification for dsci_hash_method_type. Each of the non-VCL NAL units and VCL NAL units having a NAL unit type identifier corresponding to the values ​​in NonVclDigitallySignedNalUnitsList may be associated with one of the NumVerificationSubstream message digests. Here, at least one of the non-VCL NAL units or the VCL NAL units may follow the DSCI SEI message. The verification substream ID may be indicated by the DSCS SEI message. Alternatively, if no DSCS SEI message exists for a specific picture unit (PU), the verification substream ID may be inferred as 0.

[0145] The message for calculating the k-th message digest can be obtained by concatenating all non-VCL NAL units with NAL unit type identifiers corresponding to values ​​in nonVclDigitallySignedNalUnitsList and VCL NAL units associated with the k-th verification substream. k can be in the range from 0 to dsci_num_verification_substreams_minus1.

[0146] The calculation of the message digest can be performed on a block basis. Here, the block size can be defined as shown in Table 2 according to dsci_hash_method_type.

[0147] For each of the non-VCL NAL units and VCL NAL units having a NAL unit type identifier corresponding to the values ​​in nonVclDigitallySignedNalUnitsList, the corresponding message digest can be updated according to the algorithm specified in NIST FIPS PUB 180-4 for the specified dsci_hash_method_type. Since the message digest is calculated for the concatenation of non-VCL NAL units and VCL NAL units for the verification substream, it is common for the processing block to be split and processed across two or more consecutive NAL units.

[0148] A DSCS SEI message can provide a mechanism for associating an encoded picture with one of the verification substreams indicated in the DSCI SEI message.

[0149] If an AU contains both DSCI SEI messages and DSCS SEI messages, the DSCI SEI message must come before the DSCS SEI message in the decoding order.

[0150] If a CVS does not contain DSCI SEI messages, the CLVS (coded layer video sequence) of that CVS must not contain DSCS SEI messages.

[0151] If a DSCS SEI message exists in an AU of CVS, it must come before all non-VCL NAL units and all VCL NAL units of the AU that have NAL unit type identifiers corresponding to the values ​​in nonVclDigitallySignedNalUnitsList in the decoding order.

[0152] Table 4 is an example of a DSCS SEI message according to the present disclosure.

[0153] digitally_signed_content_selection( payloadSize ) {Descriptordscs_verification_substream_idu(8)}

[0154] DSCS SEI messages may include a substream identifier (dscs_verification_substream_id).

[0155] dscs_verification_substream_id may represent a verification substream to which non-VCL NAL units and VCL NAL units are assigned, having NAL unit type identifiers corresponding to values ​​in nonVclDigitallySignedNalUnitsList of the currently encoded picture.

[0156] If a DSCI SEI message exists for the currently encoded video sequence but no DSCS SEI message exists for the encoded picture, the value of dscs_verification_substream_id can be inferred to be 0. The value of dscs_verification_substream_id must be within the range from 0 to dsci_num_verification_substreams_minus1.

[0157] The message digest of the verification substream corresponding to dscs_verification_substream_id can be updated based on non-VCL NAL units and VCL NAL units having NAL unit type identifiers corresponding to the values ​​in nonVclDigitallySignedNalUnitsList of the currently encoded picture, according to dsci_hash_method_type specified in the preceding DSCI SEI message.

[0158] dscs_verification_substream_id may be encoded as a descriptor of u(8). That is, dscs_verification_substream_id may be an 8-bit syntax element encoded as an unsigned integer.

[0159] DSCV SEI messages can provide a mechanism for verifying the digital signature of video content.

[0160] If a CVS does not contain DSCI SEI messages, the CLVS of that CVS must not contain DSCV SEI messages.

[0161] If an AU contains both DSCI SEI messages and DSCV SEI messages, the DSCI SEI message must precede the DSCV SEI message. If a PU contains both DSCS SEI messages and DSCV SEI messages, the DSCS SEI message must precede the DSCV SEI message.

[0162] If a DSCV SEI message exists in the PU of CVS, nonVCL NAL units (having NAL unit type identifiers corresponding to values ​​in nonVclDigitallySignedNalUnitsList) and / or VCL NAL units may not be assigned to the substream indicated by dscv_verification_substream_id unless one or more of the following conditions are true.

[0163] - The bitstream ends.

[0164] - A new CVS begins.

[0165] - A new DSCI SEI message is received.

[0166] Table 5 is an example of a DSCV SEI message according to the present disclosure.

[0167] digitally_signed_content_verification( payloadSize ) {Descriptordscv_verification_substream_idu(8)dscv_signature_length_in_octets_minus1u(16)dscv_signatureu(v)}

[0168] A DSCV SEI message may include a substream identifier (dscv_verification_substream_id). dscv_verification_substream_id may indicate the verification substream to which the SEI message applies.

[0169] A DSCV SEI message may include signature length information (dscv_signature_length_in_octets_minus1). A value obtained by adding 1 to dscv_signature_length_in_octets_minus1 can specify the length of dscv_signature in octets (1 octet = 8 bits).

[0170] A DSCV SEI message may include signature information (dscv_signature). dscv_signature may include a digital signature for the verification substream indicated by dscv_verification_substream_id.

[0171] Verification of a bitstream signature according to the present disclosure may be configured in the following order.

[0172] 1. The calculation of the message digest (CurrDigest) is completed as follows:

[0173] - For a verification substream with the same ID as dscv_verification_substream_id, the concatenation of non-VCL NAL units and VCL NAL units with NAL unit type identifiers corresponding to the values ​​in nonVclDigitallySignedNalUnitsList is padded according to the specifications of NIST FIPS PUB 180-4.

[0174] - The calculation of the message digest (CurrDigest) is completed in accordance with the NIST FIPS PUB 180-4 standard.

[0175] 2. The reference message digest (RefDigest) is determined as follows:

[0176] - If dscv_verification_substream_id is greater than 0, the reference message digest (RefDigest) is the last calculated message digest for the verification substream with the same ID as (dscv_verification_substream_id - 1). The DSCV SEI message corresponding to (dscv_verification_substream_id - 1) must exist before the DSCV SEI message corresponding to dscv_verification_substream_id.

[0177] - Otherwise, if the current DSCV SEI message is the first DSCV SEI message with a verification ID of 0 in the encoded video sequence and the previous encoded video sequence does not contain a DSCI SEI message (this includes the case where the current encoded video sequence is the first encoded video sequence in the bitstream), RefDigest is set to a bitstring consisting of DigestSize bits equal to 1. Here, DigestSize may mean the size of the message digest.

[0178] - In other cases, the reference message digest (RefDigest) is the last calculated message digest for the validation substream with an ID equal to 0.

[0179] 3. The identification string (IdString) may be constructed by concatenating at least one binary representation of the reference message digest (RefDigest), current message digest (CurrDigest), dsci_hash_method_type, or dsci_content_uuid.

[0180] The number of bits in RefDigest can be determined by the dsci_hash_method_type value that was valid when calculating the RefDigest value. The number of bits in CurrDigest can be determined by the current value of dsci_hash_method_type. The value of dsci_hash_method_type can be represented by 8 bits. The value of dsci_content_uuid can be represented by 128 bits.

[0181] 4. An identification string (IdString) may represent a message used to verify a signature. The signature verification algorithm and the public key used to verify the signature may be indicated based on at least one of dsci_use_key_register_idx_flag, dsci_key_source_uri, or dsci_key_register_idx.

[0182] Since the Bitstring used for signature verification includes the RefDigest, it is possible not only to verify whether the nonVCL NAL units and VCL NAL units used to calculate the current message digest are correct, but also to additionally verify whether additional nonVCL NAL units or VCL NAL units have been inserted into the bitstream, or whether nonVCL NAL units or VCL NAL units have been removed from the bitstream.

[0183] When the decoding device accesses the bitstream, the IdString configured for the first DSCV SEI message cannot be verified. This is because the value of RefDigest cannot be calculated correctly. However, starting from the second DSCV SEI message, the signature can be verified.

[0184] After verification is complete, the message digest for the verification substream corresponding to dscv_verification_substream_id can be re-initialized according to the NIST FIPS PUB 180-4 standard based on the specified dsci_hash_method_type.

[0185] Currently, in DSCS SEI messages, a single DSCS SEI message is applied to a single encoded picture. If a DSCS SEI message with the same content is repeatedly applied to two or more consecutive encoded pictures (i.e., if the same dscs_verification_substream_id is assigned to two or more consecutive encoded pictures), duplicate DSCS SEI messages may exist for all encoded pictures, which may be inefficient. Accordingly, the present disclosure proposes various embodiments to solve the aforementioned problem. The following embodiments may be applied individually or at least two in combination.

[0186] Example 1

[0187] DSCS SEI messages can be applied to the currently encoded picture and all subsequent encoded pictures. DSCS SEI messages can be applied until one or more of the following conditions are true.

[0188] - The bitstream ends.

[0189] - A new CVS begins.

[0190] - A new DSCS SEI message is received.

[0191] DSCS SEI messages may include a substream identifier (dscs_verification_substream_id).

[0192] dscs_verification_substream_id may represent a verification substream to which the VCL NAL units of the encoded picture to which the current DSCS SEI message applies, and the associated non-VCL NAL units having NAL unit type identifiers corresponding to the values ​​in nonVclDigitallySignedNalUnitsList for those VCL NAL units belong.

[0193] If a DSCI SEI message exists in the currently encoded video sequence but a DSCS SEI message is applied to the encoded picture, the value of dscs_verification_substream_id can be inferred as 0. The value of dscs_verification_substream_id can be restricted to a range from 0 to dsci_num_verification_substreams_minus1.

[0194] The message digest of the verification substream corresponding to dscs_verification_substream_id can be updated based on non-VCL NAL units and VCL NAL units having NAL unit type identifiers corresponding to the values ​​in nonVclDigitallySignedNalUnitsList of the currently encoded picture, according to dsci_hash_method_type specified in the preceding DSCI SEI message.

[0195] Example 2

[0196] Table 6 is an example of a DSCS SEI message according to the present disclosure.

[0197] digitally_signed_content_selection( payloadSize ) {Descriptordscs_cancel_flagu(1)if( !dscs_cancel_flag ) {dscs_persistence_flagu(1)dscs_verification_substream_idu(8)}}

[0198] According to Table 6, DSCS SEI messages may include a DSCS cancellation flag (dscs_cancel_flag).

[0199] If the value of dscs_cancel_flag is 1, it may indicate that the DSCS SEI message cancels the persistence of the previous DSCS SEI message in the output order. If the value of dscs_cancel_flag is 0, it may indicate that information about the DSCS follows.

[0200] DSCS SEI messages can include a DSCS persistence flag (dscs_persistence_flag).

[0201] dscs_persistence_flag can indicate the persistence of DSCS SEI messages. For example, if the value of dscs_persistence_flag is 0, it may indicate that the DSCS SEI message applies only to the currently decrypted picture. If the value of dscs_persistence_flag is 1, it may indicate that the DSCS SEI message applies to the currently decrypted picture and persists to all subsequent pictures until one or more of the following conditions are true.

[0202] - A new CVS begins.

[0203] - The bitstream ends.

[0204] - A new DSCS SEI message is received.

[0205] dscs_persistence_flag can be adaptively signaled based on dscs_cancel_flag. For example, dscs_persistence_flag can be signaled based on the value of dscs_cancel_flag being 0. dscs_persistence_flag can not be signaled based on the value of dscs_cancel_flag being 1.

[0206] DSCS SEI messages may include a substream identifier (dscs_verification_substream_id).

[0207] dscs_verification_substream_id may represent a verification substream to which the VCL NAL units of the encoded picture to which the current DSCS SEI message applies, and the associated non-VCL NAL units having NAL unit type identifiers corresponding to the values ​​in nonVclDigitallySignedNalUnitsList for those VCL NAL units belong.

[0208] If a DSCI SEI message exists in the currently encoded video sequence but a DSCS SEI message is applied to the encoded picture, the value of dscs_verification_substream_id can be inferred as 0. The value of dscs_verification_substream_id can be restricted to a range from 0 to dsci_num_verification_substreams_minus1.

[0209] The message digest of the verification substream corresponding to dscs_verification_substream_id can be updated based on non-VCL NAL units and VCL NAL units having NAL unit type identifiers corresponding to the values ​​in nonVclDigitallySignedNalUnitsList of the currently encoded picture, according to dsci_hash_method_type specified in the preceding DSCI SEI message.

[0210] Example 3

[0211] Table 7 is an example of a table defining the persistence range of an SEI message according to the present disclosure.

[0212] SEI messagePersistence scopeFiller payloadThe PU containing the SEI messageUser data registered by Rec. ITU-T T.35UnspecifiedUser data unregisteredUnspecifiedFilm grain characteristicsSpecified by the syntax of the SEI messageFrame packing arrangementSpecified by the syntax of the SEI messageParameter sets inclusion indicationThe CLVS containing the SEI messageDecoded picture hashThe PU containing the SEI messageMastering display colour volumeThe CLVS containing the SEI messageContent light level informationThe CLVS containing the SEI messageDRAP indicationThe picture associated with the SEI messageAlternative transfer characteristicsThe CLVS containing the SEI messageAmbient viewing environmentThe CLVS containing the SEI messageContent colour volumeSpecified by the syntax of the SEI messageEquirectangular projectionSpecified by the syntax of the SEI messageGeneralized cubemap projectionSpecified by the syntax of the SEI messageSphere rotationSpecified by the syntax of the SEImessageRegion-wise packingSpecified by the syntax of the SEI messageOmnidirectional viewportSpecified by the syntax of the SEI messageFrame-field informationThe PU containing the SEI messageSample aspect ratio informationSpecified by the syntax of the SEI messageAnnotated regionsSpecified by the syntax of the SEI messageScalability dimension informationThe CVS containing the SEI messageMultiview acquisition informationThe CVS containing the SEI messageMultiview view positionThe CVS containing the SEI messageDepth representation informationSpecified by the semantics of the SEI messageAlpha channel informationSpecified by the syntax of the SEI messageExtended DRAP indicationThe picture associated with the SEI messageDisplay orientationSpecified by the syntax of the SEI messageColour transform informationSpecified by the syntax of the SEI messageShutter interval informationThe CLVS containing the SEI messageNeural-network post-filter characteristicsThe CLVS containing the SEImessageNeural-network post-filter activationSpecified by the syntax of the SEI messagePhase indicationSpecified by the semantics of the SEI messageSEI processing orderFor each value of po_id, the number of SEI messages and the payloadType codes of the SEI messages indicated within the SEI processing order SEI message persist for the CVS containing the SEI processing order SEI message.Processing order nestingDepending on the processing-order-nested SEI messages. Each processing-order-nested SEI message has the same persistence scope as if the SEI message was not nested.Encoder optimization informationSpecified by the syntax of the SEI messageSource picture timing informationSpecified by the syntax of the SEI messageObject mask informationSpecified by the syntax of the SEI messageModality informationSpecified by the syntax of the SEI messageText descriptionsSpecified by the syntax of the SEI messageDigitally signed content selectionSpecified by the semantics of the SEI message

[0213] According to Table 7, the persistence range of a DSCS SEI message can be determined by the semantics of the DSCS SEI message.

[0214] Example 4

[0215] Table 8 is an example of a table defining the persistence range of an SEI message according to the present disclosure.

[0216] SEI messagePersistence scopeFiller payloadThe PU containing the SEI messageUser data registered by Rec. ITU-T T.35UnspecifiedUser data unregisteredUnspecifiedFilm grain characteristicsSpecified by the syntax of the SEI messageFrame packing arrangementSpecified by the syntax of the SEI messageParameter sets inclusion indicationThe CLVS containing the SEI messageDecoded picture hashThe PU containing the SEI messageMastering display colour volumeThe CLVS containing the SEI messageContent light level informationThe CLVS containing the SEI messageDRAP indicationThe picture associated with the SEI messageAlternative transfer characteristicsThe CLVS containing the SEI messageAmbient viewing environmentThe CLVS containing the SEI messageContent colour volumeSpecified by the syntax of the SEI messageEquirectangular projectionSpecified by the syntax of the SEI messageGeneralized cubemap projectionSpecified by the syntax of the SEI messageSphere rotationSpecified by the syntax of the SEImessageRegion-wise packingSpecified by the syntax of the SEI messageOmnidirectional viewportSpecified by the syntax of the SEI messageFrame-field informationThe PU containing the SEI messageSample aspect ratio informationSpecified by the syntax of the SEI messageAnnotated regionsSpecified by the syntax of the SEI messageScalability dimension informationThe CVS containing the SEI messageMultiview acquisition informationThe CVS containing the SEI messageMultiview view positionThe CVS containing the SEI messageDepth representation informationSpecified by the semantics of the SEI messageAlpha channel informationSpecified by the syntax of the SEI messageExtended DRAP indicationThe picture associated with the SEI messageDisplay orientationSpecified by the syntax of the SEI messageColour transform informationSpecified by the syntax of the SEI messageShutter interval informationThe CLVS containing the SEI messageNeural-network post-filter characteristicsThe CLVS containing the SEImessageNeural-network post-filter activationSpecified by the syntax of the SEI messagePhase indicationSpecified by the semantics of the SEI messageSEI processing orderFor each value of po_id, the number of SEI messages and the payloadType codes of the SEI messages indicated within the SEI processing order SEI message persist for the CVS containing the SEI processing order SEI message.Processing order nestingDepending on the processing-order-nested SEI messages. Each processing-order-nested SEI message has the same persistence scope as if the SEI message was not nested.Encoder optimization informationSpecified by the syntax of the SEI messageSource picture timing informationSpecified by the syntax of the SEI messageObject mask informationSpecified by the syntax of the SEI messageModality informationSpecified by the syntax of the SEI messageText descriptionsSpecified by the syntax of the SEI messageDigitally signed content selectionSpecified by the syntax of the SEI message

[0217] According to Table 8, the persistence range of a DSCS SEI message can be determined by the syntax of the DSCS SEI message.

[0218] Example 5

[0219] Table 9 is an example of a table defining the persistence range of an SEI message according to the present disclosure.

[0220] SEI messagePersistence scopeFiller payloadThe PU containing the SEI messageUser data registered by Rec. ITU-T T.35UnspecifiedUser data unregisteredUnspecifiedFilm grain characteristicsSpecified by the syntax of the SEI messageFrame packing arrangementSpecified by the syntax of the SEI messageParameter sets inclusion indicationThe CLVS containing the SEI messageDecoded picture hashThe PU containing the SEI messageMastering display colour volumeThe CLVS containing the SEI messageContent light level informationThe CLVS containing the SEI messageDRAP indicationThe picture associated with the SEI messageAlternative transfer characteristicsThe CLVS containing the SEI messageAmbient viewing environmentThe CLVS containing the SEI messageContent colour volumeSpecified by the syntax of the SEI messageEquirectangular projectionSpecified by the syntax of the SEI messageGeneralized cubemap projectionSpecified by the syntax of the SEI messageSphere rotationSpecified by the syntax of the SEImessageRegion-wise packingSpecified by the syntax of the SEI messageOmnidirectional viewportSpecified by the syntax of the SEI messageFrame-field informationThe PU containing the SEI messageSample aspect ratio informationSpecified by the syntax of the SEI messageAnnotated regionsSpecified by the syntax of the SEI messageScalability dimension informationThe CVS containing the SEI messageMultiview acquisition informationThe CVS containing the SEI messageMultiview view positionThe CVS containing the SEI messageDepth representation informationSpecified by the semantics of the SEI messageAlpha channel informationSpecified by the syntax of the SEI messageExtended DRAP indicationThe picture associated with the SEI messageDisplay orientationSpecified by the syntax of the SEI messageColour transform informationSpecified by the syntax of the SEI messageShutter interval informationThe CLVS containing the SEI messageNeural-network post-filter characteristicsThe CLVS containing the SEImessageNeural-network post-filter activationSpecified by the syntax of the SEI messagePhase indicationSpecified by the semantics of the SEI messageSEI processing orderFor each value of po_id, the number of SEI messages and the payloadType codes of the SEI messages indicated within the SEI processing order SEI message persist for the CVS containing the SEI processing order SEI message.Processing order nestingDepending on the processing-order-nested SEI messages. Each processing-order-nested SEI message has the same persistence scope as if the SEI message was not nested.Encoder optimization informationSpecified by the syntax of the SEI messageSource picture timing informationSpecified by the syntax of the SEI messageObject mask informationSpecified by the syntax of the SEI messageModality informationSpecified by the syntax of the SEI messageText descriptionsSpecified by the syntax of the SEI messageDigitally signed content selectionThe PU containing the SEI message

[0221] According to Table 9, the persistence range of a DSCS SEI message may be a picture unit (PU) containing the DSCS SEI message.

[0222] Example 6

[0223] Table 10 is an example of a table defining the persistence range of an SEI message according to the present disclosure.

[0224] SEI messagePersistence scopeFiller payloadThe PU containing the SEI messageUser data registered by Rec. ITU-T T.35UnspecifiedUser data unregisteredUnspecifiedFilm grain characteristicsSpecified by the syntax of the SEI messageFrame packing arrangementSpecified by the syntax of the SEI messageParameter sets inclusion indicationThe CLVS containing the SEI messageDecoded picture hashThe PU containing the SEI messageMastering display colour volumeThe CLVS containing the SEI messageContent light level informationThe CLVS containing the SEI messageDRAP indicationThe picture associated with the SEI messageAlternative transfer characteristicsThe CLVS containing the SEI messageAmbient viewing environmentThe CLVS containing the SEI messageContent colour volumeSpecified by the syntax of the SEI messageEquirectangular projectionSpecified by the syntax of the SEI messageGeneralized cubemap projectionSpecified by the syntax of the SEI messageSphere rotationSpecified by the syntax of the SEImessageRegion-wise packingSpecified by the syntax of the SEI messageOmnidirectional viewportSpecified by the syntax of the SEI messageFrame-field informationThe PU containing the SEI messageSample aspect ratio informationSpecified by the syntax of the SEI messageAnnotated regionsSpecified by the syntax of the SEI messageScalability dimension informationThe CVS containing the SEI messageMultiview acquisition informationThe CVS containing the SEI messageMultiview view positionThe CVS containing the SEI messageDepth representation informationSpecified by the semantics of the SEI messageAlpha channel informationSpecified by the syntax of the SEI messageExtended DRAP indicationThe picture associated with the SEI messageDisplay orientationSpecified by the syntax of the SEI messageColour transform informationSpecified by the syntax of the SEI messageShutter interval informationThe CLVS containing the SEI messageNeural-network post-filter characteristicsThe CLVS containing the SEImessageNeural-network post-filter activationSpecified by the syntax of the SEI messagePhase indicationSpecified by the semantics of the SEI messageSEI processing orderFor each value of po_id, the number of SEI messages and the payloadType codes of the SEI messages indicated within the SEI processing order SEI message persist for the CVS containing the SEI processing order SEI message.Processing order nestingDepending on the processing-order-nested SEI messages. Each processing-order-nested SEI message has the same persistence scope as if the SEI message was not nested.Encoder optimization informationSpecified by the syntax of the SEI messageSource picture timing informationSpecified by the syntax of the SEI messageObject mask informationSpecified by the syntax of the SEI messageModality informationSpecified by the syntax of the SEI messageText descriptionsSpecified by the syntax of the SEI messageDigitally signed content selectionThe picture associated with the SEI message

[0225] According to Table 10, the persistence range of a DSCS SEI message can be the picture associated with the DSCS SEI message.

[0226] Example 7

[0227] DSCS SEI messages can be applied to the current picture and all subsequent pictures. Alternatively, DSCS SEI messages can be applied to the current subpicture and all subsequent subpictures. As such, DSCS SEI messages can be selectively applied to either the picture or the subpicture.

[0228] For example, a DSCS SEI message may be applied to at least one of the NAL units of the current picture (or subpicture) or all subsequent NAL units of the current picture (or subpicture). In this case, the DSCS SEI message may be applied until one or more of the following conditions are true.

[0229] - The bitstream ends.

[0230] - A new CVS begins.

[0231] - A new DSCS SEI message is received.

[0232] DSCS SEI messages may include a substream identifier (dscs_verification_substream_id).

[0233] dscs_verification_substream_id may represent a verification substream to which the VCL NAL units of the encoded picture or subpicture to which the current DSCS SEI message applies, and the associated non-VCL NAL units having NAL unit type identifiers corresponding to the values ​​in nonVclDigitallySignedNalUnitsList for those VCL NAL units belong.

[0234] If a DSCI SEI message exists in the currently encoded video sequence but the DSCS SEI message applies to the encoded picture or subpicture, the value of dscs_verification_substream_id can be inferred as 0. The value of dscs_verification_substream_id can be restricted to a range from 0 to dsci_num_verification_substreams_minus1.

[0235] The message digest of the verification substream corresponding to dscs_verification_substream_id can be updated based on non-VCL NAL units and VCL NAL units having NAL unit type identifiers corresponding to the values ​​in nonVclDigitallySignedNalUnitsList of the currently encoded picture (or subpicture), according to the dsci_hash_method_type specified in the preceding DSCI SEI message.

[0236] A DSC SEI message according to the present disclosure may be included in a network abstraction layer (NAL) unit of a bitstream. Alternatively, information defined in a DSC SEI message according to the present disclosure may be configured in a high-level syntax of a bitstream. Here, the high-level syntax may be at least one of a sequence parameter set (SPS), a picture parameter set (PPS), a picture header (PH), or a slice header (SH). Alternatively, a DSC SEI message according to the present disclosure may be defined as a separate NAL unit type within the bitstream.

[0237] FIG. 5 illustrates a schematic configuration of a decoding device (300) that performs a method for restoring a video picture according to the present disclosure.

[0238] Referring to FIG. 5, the decoding device (300) may include a receiving unit (500), a video information extraction unit (510), and a video restoration unit (520).

[0239] The receiver (500) can receive a bitstream including an encoded video picture.

[0240] The video information extraction unit (510) can extract video information regarding an encoded video picture from the bitstream. Additionally, the video information extraction unit (710) can extract a DSC SEI message from the bitstream, as seen with reference to FIG. 4.

[0241] The video restoration unit (520) can restore an encoded video picture based on extracted video information.

[0242] FIG. 6 illustrates a method for generating a bitstream performed in an encoding device (200) according to the present disclosure.

[0243] A video picture being encoded can be received (S600).

[0244] Video information regarding the video picture can be generated by encoding the received video picture (S610).

[0245] A bitstream containing video information about a video picture can be generated (S420).

[0246] In addition, a DSC SEI message applied to the bitstream can be generated, as seen with reference to FIG. 4. The generated DSC SEI message may be included in the bitstream. Alternatively, the information defined in the DSC SEI message may be configured in the high-level syntax of the bitstream.

[0247] FIG. 7 illustrates a schematic configuration of an encoding device (200) that performs a method for generating a bitstream according to the present disclosure.

[0248] Referring to FIG. 7, the encoding device (200) may include a receiving unit (700), a video compression unit (710), and a bitstream generation unit (720).

[0249] The receiver (700) can receive one or more video pictures that are encoded.

[0250] The video compression unit (710) can generate video information regarding the video picture by encoding one or more received video pictures. The video compression unit (710) can generate a DSC SEI message applied to the bitstream.

[0251] The bitstream generation unit (720) can generate a bitstream including the video information. The bitstream generation unit (720) can generate a bitstream that further includes the generated DSC SEI message.

[0252] In the embodiments described above, methods are described based on flowcharts as a series of steps or blocks; however, the embodiments are not limited to the order of the steps, and some steps may occur in a different order or simultaneously with other steps as described above. Furthermore, those skilled in the art will understand that the steps shown in the flowcharts are not exclusive, and other steps may be included, or one or more steps of the flowcharts may be omitted without affecting the scope of the embodiments of this document.

[0253] The method according to the embodiments of the present document described above may be implemented in the form of software, and the encoding device and / or decoding device according to the present document may be included in a device that performs image processing, such as a TV, computer, smartphone, set-top box, display device, etc.

[0254] When the embodiments described in this document are implemented in software, the method described above may be implemented as a module (process, function, etc.) that performs the function described above. The module may be stored in memory and executed by a processor. The memory may be located inside or outside the processor and may be connected to the processor by various well-known means. The processor may include an application-specific integrated circuit (ASIC), other chipsets, logic circuits, and / or data processing devices. The memory may include read-only memory (ROM), random access memory (RAM), flash memory, memory cards, storage media, and / or other storage devices. That is, the embodiments described in this document may be implemented and executed on a processor, microprocessor, controller, or chip. For example, the functional units illustrated in each figure may be implemented and executed on a computer, processor, microprocessor, controller, or chip. In this case, information on instructions or algorithms for implementation may be stored on a digital storage medium.

[0255] In addition, the decoding device and encoding device to which the embodiment(s) of the present specification are applied may be included in multimedia broadcasting transmission and reception devices, mobile communication terminals, home cinema video devices, digital cinema video devices, surveillance cameras, video conversation devices, real-time communication devices such as video communication, mobile streaming devices, storage media, camcorders, Video on Demand (VoD) service providers, Over-the-top video (OTT) devices, internet streaming service providers, 3D video devices, virtual reality (VR) devices, augmented reality (AR) devices, video phone video devices, transportation terminals (e.g., vehicle terminals (including autonomous vehicles), airplane terminals, ship terminals, etc.), and medical video devices, and may be used to process video signals or data signals. For example, Over-the-top video (OTT) devices may include game consoles, Blu-ray players, internet-connected TVs, home theater systems, smartphones, tablet PCs, Digital Video Recorders (DVRs), etc.

[0256] Additionally, the processing method to which the embodiment(s) of this specification are applied may be produced in the form of a program that is executed by a computer and may be stored on a computer-readable recording medium. Multimedia data having a data structure according to the embodiment(s) of this specification may also be stored on a computer-readable recording medium. The computer-readable recording medium includes all types of storage devices and distributed storage devices in which computer-readable data is stored. The computer-readable recording medium may include, for example, a Blu-ray disc (BD), a Universal Serial Bus (USB), a ROM, a PROM, an EPROM, an EEPROM, a RAM, a CD-ROM, a magnetic tape, a floppy disk, and an optical data storage device. Additionally, the computer-readable recording medium includes a medium implemented in the form of a carrier wave (e.g., transmission over the Internet). Additionally, a bitstream generated by an encoding method may be stored on a computer-readable recording medium or transmitted via a wired or wireless communication network.

[0257] Additionally, the embodiments of this specification may be implemented as a computer program product by program code, and said program code may be executed on a computer by the embodiments of this specification. said program code may be stored on a carrier readable by a computer.

[0258] FIG. 8 shows an example of a content streaming system to which embodiments of the present disclosure can be applied.

[0259] Referring to FIG. 8, a content streaming system to which the embodiment(s) of the present specification are applied may largely include an encoding server, a streaming server, a web server, a media storage, a user device, and a multimedia input device.

[0260] The above encoding server compresses content input from multimedia input devices, such as smartphones, cameras, and camcorders, into digital data to generate a bitstream and transmits it to the streaming server. As another example, if multimedia input devices, such as smartphones, cameras, and camcorders, generate the bitstream directly, the encoding server may be omitted.

[0261] The bitstream above may be generated by an encoding method or a bitstream generation method to which the embodiment(s) of the present specification are applied, and the streaming server may temporarily store the bitstream during the process of transmitting or receiving the bitstream.

[0262] The streaming server transmits multimedia data to a user device based on a user request via a web server, and the web server acts as a medium to inform the user of available services. When a user requests a desired service from the web server, the web server transmits it to the streaming server, and the streaming server transmits the 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 plays the role of controlling commands and responses between each device within the content streaming system.

[0263] The streaming server may receive content from a media storage and / or an encoding server. For example, when receiving content from the encoding server, the content may be received in real time. In this case, to provide a seamless streaming service, the streaming server may store the bitstream for a certain period of time.

[0264] Examples of the above user devices may include mobile phones, smartphones, laptop computers, digital broadcasting terminals, PDAs (personal digital assistants), PMPs (portable multimedia players), navigation systems, slate PCs, tablet PCs, ultrabooks, wearable devices (e.g., smartwatches, smart glasses, HMDs (head-mounted displays)), digital TVs, desktop computers, digital signage, etc.

[0265] Each server within the above-mentioned content streaming system can be operated as a distributed server, and in this case, data received from each server can be processed in a distributed manner.

[0266] The claims described in this specification may be combined in various ways. For example, the technical features of the method claims in this specification may be combined to be implemented as a device, and the technical features of the device claims in this specification may be combined to be implemented as a method. Furthermore, the technical features of the method claims and the technical features of the device claims in this specification may be combined to be implemented as a device, and the technical features of the method claims and the technical features of the device claims in this specification may be combined to be implemented as a method.

Claims

1. A step of receiving a bitstream including an encoded video picture; and The method includes the step of restoring an encoded video picture contained in the bitstream, The above bitstream includes a digitally signed content (DSC) SEI (supplemental enhancement information) message, and The above DSC SEI message includes at least one of a digitally signed content initialization (DSCI) SEI message, a digitally signed content selection (DSCS) SEI message, or a digitally signed content verification (DSCV) SEI message. The above DSCS SEI message includes a substream identifier, and A method for obtaining the above DSC SEI message from the NAL (network abstraction layer) unit of the bitstream.

2. In Paragraph 1, A method in which the above DSCS SEI message is applied to the currently encoded picture and all subsequent encoded pictures.

3. In Paragraph 1, A method in which the above substream identifier represents a verification substream to which related non-VCL NAL units have NAL unit type identifiers corresponding to the VCL NAL units of the encoded picture to which the current DSCS SEI message is applied, and the values ​​in a predetermined list for the VCL NAL units.

4. In Paragraph 1, The above DSCS SEI message further includes a DSCS cancellation flag, and A method in which the above DSCS cancellation flag with a value of 1 indicates that the above DSCS SEI message cancels the persistence of the previous DSCS SEI message in the output order, and the above DSCS cancellation flag with a value of 0 indicates that information about the DSCS follows.

5. In Paragraph 1, A method in which the above DSCS SEI message further includes a DSCS persistence flag indicating the persistence of the above DSCS SEI message.

6. In Paragraph 1, A method in which the persistence range of the above DSCS SEI message is determined by the semantics of the above DSCS SEI message.

7. In Paragraph 1, A method in which the persistence range of the above DSCS SEI message is determined by the syntax of the above DSCS SEI message.

8. In Paragraph 1, A method in which the persistence range of the above DSCS SEI message is a picture unit (PU) containing the above DSCS SEI message.

9. In Paragraph 1, The persistence range of the above DSCS SEI message is a method, which is a picture associated with the above DSCS SEI message.

10. In Paragraph 1, A method in which the above DSCI SEI message is optionally applied to either a picture or a subpicture.

11. A step of receiving a video picture to be encoded; A step of encoding the received video picture to generate video information regarding the video picture; A step of generating a digitally signed content (DSC) SEI (supplemental enhancement information) message; and The method includes the step of generating a bitstream including the video information and the DSC SEI message, The above DSC SEI message includes at least one of a digitally signed content initialization (DSCI) SEI message, a digitally signed content selection (DSCS) SEI message, or a digitally signed content verification (DSCV) SEI message. The above DSCS SEI message includes a substream identifier, and A method in which the above DSC SEI message is encoded in the NAL (network abstraction layer) unit of the above bitstream.

12. A non-transient computer-readable storage medium for storing a bitstream generated by the method according to paragraph 11.

13. A step of generating a bitstream; wherein the bitstream is generated based on the steps of receiving a video picture to be encoded, encoding the received video picture to generate video information regarding the video picture, and generating a digitally signed content (DSC) SEI (supplemental enhancement information) message, and The method includes the step of transmitting data including the above bitstream, The above DSC SEI message includes at least one of a digitally signed content initialization (DSCI) SEI message, a digitally signed content selection (DSCS) SEI message, or a digitally signed content verification (DSCV) SEI message. The above DSCS SEI message includes a substream identifier, and A method in which the above DSC SEI message is encoded in the NAL (network abstraction layer) unit of the above bitstream.

Images