Method and apparatus for signaling picture partition information

Abstract

To provide a method and apparatus for signaling picture partitioning information in an image coding system for improving overall image / video compression efficiency and improving efficiency of picture partitioning.SOLUTION: An image decoding method performed by a decoding apparatus comprises the steps of: obtaining image information on a current picture from a bitstream; and decoding the current picture based on the image information, where the image information includes a first flag related to the presence of subpicture information and a second flag related to whether each subpicture includes a single slice, and the number of slices included in the current picture is derived to be equal to 1 based on that a value of the first flag is equal to 0 and that a value of the second flag is equal to 1. That the second flag is equal to 1 indicates that each subpicture is constituted of a single slice.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present disclosure relates to video coding techniques and to a method and apparatus for signaling picture partition information in a video coding system. [Background technology]

[0002] Recently, the demand for high-resolution, high-quality video, such as HD (High Definition) video and UHD (Ultra High Definition) video, is increasing in various fields. As video data becomes higher in resolution and quality, the amount of information or bits to be transmitted increases relatively compared to existing video data. Therefore, when video data is transmitted using existing media such as wired or wireless broadband lines or stored using existing storage media, transmission costs and storage costs increase.

[0003] Therefore, a highly efficient video compression technique is required to effectively transmit, store, and play back high-resolution, high-quality video information. Summary of the Invention [Problem to be solved by the invention]

[0004] A technical problem of the present disclosure is to provide a method and apparatus for improving video coding efficiency.

[0005] Another technical problem of the present disclosure is to provide a method and apparatus for signaling picture partition information.

[0006] Another technical object of the present disclosure is to provide a method and apparatus for performing decoding for a current picture based on partition information for the current picture. [Means for solving the problem]

[0007] According to an embodiment of the present disclosure, there is provided a video decoding method executed by a decoding device, the method including the steps of: acquiring video information for a current picture from a bitstream; and decoding the current picture based on the video information, the video information including a first flag indicating whether sub-picture information is present and a second flag indicating whether the sub-picture includes only one slice; and deriving the number of slices included in the current picture to be one based on the first and second flags.

[0008] According to another embodiment of the present disclosure, there is provided a video encoding method executed by an encoding apparatus, the method including: dividing a current picture to derive at least one slice; and encoding video information for the current picture based on the at least one slice, the video information including a first flag indicating whether sub-picture information is present and a second flag indicating whether the sub-picture includes only one slice; and determining that the number of slices included in the current picture is one based on the first and second flags.

[0009] According to another embodiment of the present disclosure, there is provided a computer-readable digital storage medium storing encoded video information for causing a decoding device to perform a video decoding method, the decoding method according to the embodiment including the steps of: acquiring video information for a current picture from a bitstream; and decoding the current picture based on the video information, the video information including a first flag indicating whether subpicture information is present and a second flag indicating whether the subpicture includes only one slice; and deriving the number of slices included in the current picture to be one based on the first and second flags. [Effects of the Invention]

[0010] According to the present invention, the overall image / video compression efficiency can be improved.

[0011] According to the present disclosure, the efficiency of picture partitioning can be improved.

[0012] According to the present disclosure, the efficiency of picture partitioning can be improved based on partition information for the current picture. [Brief explanation of the drawings]

[0013] [Figure 1] 1 illustrates a schematic diagram of an example video / image coding system to which the present disclosure is applicable; [Figure 2] 1 is a diagram illustrating a schematic configuration of a video / image encoding device to which the present disclosure can be applied. [Figure 3] 1 is a diagram illustrating a schematic configuration of a video / image decoding device to which the present disclosure can be applied. [Figure 4] 10 shows an exemplary hierarchical structure for coded data. [Figure 5] 1 is a diagram illustrating an example of partitioning a picture. [Figure 6] 1 is a flow diagram illustrating a picture encoding procedure according to an embodiment. [Figure 7] 1 is a flow diagram illustrating a picture decoding procedure according to an embodiment. [Figure 8] 1 is a flowchart illustrating an operation of an encoding device according to an embodiment. [Figure 9] FIG. 1 is a block diagram showing a configuration of an encoding device according to an embodiment. [Figure 10] 1 is a flowchart illustrating an operation of a decoding device according to an embodiment. [Figure 11] 1 is a block diagram illustrating a configuration of a decoding device according to an embodiment. [Figure 12] 1 illustrates an example of a content streaming system to which the disclosure of this document is applicable. DETAILED DESCRIPTION OF THE INVENTION

[0014] This document may be modified in various ways and may have various embodiments. Specific embodiments will be illustrated in the drawings and described in detail. However, this is not intended to limit this document to the specific embodiments. Common terms used in this document are used merely to describe specific embodiments and are not intended to limit the technical ideas of this document. A singular expression includes a plural expression unless the context clearly dictates otherwise. In this specification, the terms "comprise" or "have" are intended to specify the presence of a feature, number, step, operation, component, part, or combination thereof described in the specification, and should be understood not to preclude the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0015] Meanwhile, each component in the drawings described in this document is illustrated independently for the convenience of explaining the different characteristic functions, and does not mean that each component is realized by separate hardware or software. For example, two or more components may be combined to form a single component, or a single component may be divided into multiple components. Embodiments in which each component is integrated and / or separated are also included within the scope of this document as long as they do not deviate from the essence of this document.

[0016] As used herein, "A or B" can mean "only A," "only B," or "both A and B." In other words, as used herein, "A or B" can be interpreted as "A and / or B." For example, as used herein, "A, B, or C" can mean "only A," "only B," "only C," or "any combination of A, B, and C."

[0017] A slash ( / ) or a comma (comma) used in this document can mean "and / or." For example, "A / B" can mean "A and / or B." Therefore, "A / B" can mean "only A," "only B," or "both A and B." For example, "A, B, C" can mean "A, B, or C."

[0018] As used herein, "at least one of A and B" can mean "only A," "only B," or "both A and B." Additionally, as used herein, the expressions "at least one of A or B" and "at least one of A and / or B" can be interpreted as "at least one of A and B."

[0019] Furthermore, in this specification, "at least one of A, B, and C" can mean "only A," "only B," "only C," or "any combination of A, B, and C." Furthermore, "at least one of A, B, or C" or "at least one of A, B, and / or C" can mean "at least one of A, B, and C."

[0020] Furthermore, parentheses used herein may mean "for example." Specifically, when "prediction (intra prediction)" is used, "intra prediction" is proposed as an example of "prediction." In other words, "prediction" in this specification is not limited to "intra prediction," and "intra prediction" is proposed as an example of "prediction." Furthermore, when "prediction (i.e., intra prediction)" is used, "intra prediction" is proposed as an example of "prediction."

[0021] In this specification, technical features individually described in one drawing may be embodied individually or simultaneously.

[0022] Hereinafter, preferred embodiments of the present disclosure will be described in more detail with reference to the accompanying drawings. Hereinafter, the same reference numerals will be used to refer to the same components in the drawings, and redundant descriptions of the same components may be omitted.

[0023] FIG. 1 illustrates a schematic diagram of an example video / image coding system to which the present disclosure is applicable.

[0024] 1, a video / image coding system may include a first device (source device) and a second device (receiving device). The source device may transmit encoded video / image information or data to the receiving device in the form of a file or streaming data via a digital storage medium or a network.

[0025] The source device may include a video source, an encoding device, and a transmitting unit. The receiving device may include a receiving unit, a decoding device, and a renderer. The encoding device may be referred to as a video / video encoding device, and the decoding device may be referred to as a video / video decoding device. The transmitter may be included in the encoding device. The receiver may be included in the decoding device. The renderer may include a display unit, which may be a separate device or an external component.

[0026] A video source can acquire video / images through a video / image capture, synthesis, or generation process. A video source can include a video / image capture device and / or a video / image generation device. A video / image capture device can include, for example, one or more cameras, a video / image archive containing previously captured video / images, etc. A video / image generation device can include, for example, a computer, a tablet, a smartphone, etc., and can (electronically) generate video / images. For example, a virtual video / image can be generated via a computer, etc., in which case the video / image capture process can be replaced with a process in which related data is generated.

[0027] An 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.

[0028] The transmitter can transmit the encoded video / image information or data output in the form of a bitstream to a receiver of a receiving device via a digital storage medium or a network in the form of a file or streaming. The digital storage medium can include various storage media such as USB, SD, CD, DVD, Blu-ray, HDD, SSD, etc. The transmitter can include elements for generating a media file in a predetermined file format and elements for transmission via a broadcasting / communication network. The receiver can receive / extract the bitstream and transmit it to a decoding device.

[0029] The decoding device can decode the video / image by performing a series of steps such as inverse quantization, inverse transform, and prediction, which correspond to the operations of the encoding device.

[0030] The renderer can render the decoded video / image, and the rendered video / image can be displayed via a display unit.

[0031] This document relates to video / image coding. For example, the methods / embodiments disclosed in this document can be applied to methods disclosed in the Versatile Video Coding (VVC) standard, the Essential Video Coding (EVC) standard, the AOMedia Video 1 (AV1) standard, the 2nd generation of audio video coding standard (AVS2), or next generation video / image coding standards (e.g., H.267 or H.267).

[0032] This document presents various embodiments relating to video / image coding, and unless otherwise stated, the embodiments may be implemented in combination with each other.

[0033] In this document, video can refer to a collection of a series of images over time. A picture generally refers to a unit that shows one image at a specific time, and a slice / tile is a unit that constitutes part of a picture in coding. A slice / tile can include one or more coding tree units (CTUs). One picture can consist of one or more slices / tiles.

[0034] A tile is a rectangular region of CTUs within a particular tile column and a particular tile row in a picture. The tile column is a rectangular region of CTUs having a height equal to the height of the picture and a width specified by syntax elements in the picture parameter set. The tile row is a rectangular region of CTUs having a width specified by syntax elements in the picture parameter set and a height equal to the height of the picture.A tile scan may indicate a specific sequential ordering of CTUs partitioning a picture, where the CTUs are ordered consecutively in a CTU raster scan in a tile, whereas tiles in a picture are ordered consecutively in a raster scan of the tiles of the picture. A slice may include multiple complete tiles or multiple consecutive CTU rows within one tile of a picture, which may be included in one NAL unit. In this document, the terms tile group and slice may be used interchangeably. For example, in this document, tile group / tile group header may be referred to as slice / slice header.

[0035] On the other hand, a picture can be divided into two or more sub-pictures, each of which can be a rectangular region of one or more slices within a picture.

[0036] A pixel or a pel may refer to the smallest unit constituting a picture (or an image). A "sample" may also be used as a term corresponding to a pixel. A sample may generally refer to a pixel or a pixel value, and may refer to only a pixel / pixel value of a luma component, or may refer to only a pixel / pixel value of a chroma component.

[0037] A unit may refer to a basic unit of image processing. A unit may include at least one of a specific region of a picture and information related to the region. One unit may include one luma block and two chroma (e.g., cb, cr) blocks. The term unit may be used interchangeably with terms such as block or area. In general, an M×N block may include samples (or a sample array) consisting of M columns and N rows, or a set (or an array) of transform coefficients.

[0038] 2 is a diagram illustrating the configuration of a video / image encoding device to which this document can be applied. Hereinafter, the term "video encoding device" may include a video encoding device.

[0039] As shown in FIG. 2, the encoding apparatus 200 may 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 adder 250 may be referred to as a reconstructor or a reconstructed block generator. The image dividing unit 210, the predicting unit 220, the residual processing unit 230, the entropy encoding unit 240, the adding unit 250, and the filtering unit 260 may be configured by one or more hardware components (e.g., an encoder chipset or a processor) depending on the embodiment. Also, the memory 270 may include a decoded picture buffer (DPB) or may be configured by a digital storage medium. The hardware components may further include the memory 270 as an internal / external component.

[0040] The image division unit 210 may divide an input image (or picture, frame) input to the encoding device 200 into one or more processing units. For example, the processing units may be called coding units (CUs). In this case, the coding units may be recursively divided from a coding tree unit (CTU) or a largest coding unit (LCU) using a quad-tree, binary-tree, ternary-tree (QTBTTT) structure. For example, one coding unit may be divided into multiple coding units of deeper depths based on a quad-tree structure, a binary tree structure, and / or a ternary structure. In this case, for example, the quad-tree structure may be applied first, and then the binary tree structure and / or the ternary structure may be applied. Alternatively, the binary tree structure may be applied first. The coding procedure according to the present disclosure may be performed based on a final coding unit that is not further divided. In this case, the largest coding unit may be used as the final coding unit based on coding efficiency according to image characteristics, or the coding unit may be recursively divided into coding units of lower depths as needed, and a coding unit of an optimal size may be used as the final coding unit. Here, the coding procedure may include procedures such as prediction, transformation, and restoration, which will be described later. As another example, the processing unit may further include a prediction unit (PU) or a transform unit (TU). In this case, the prediction unit and the transform unit may each be divided or partitioned from the final coding unit.The prediction unit may be a unit of sample prediction, and the transform unit may be a unit for deriving transform coefficients and / or a unit for deriving a residual signal from the transform coefficients.

[0041] The term "unit" may be used interchangeably with terms such as "block" or "area." In general, an MxN block can refer to a set of samples or transform coefficients consisting of M columns and N rows. A sample generally refers to a pixel or pixel value, and can refer to only a pixel / pixel value of a luma component or only a pixel / pixel value of a chroma component. A sample can also be used as a term corresponding to one pixel or pel of a picture (or image).

[0042] The encoding apparatus 200 may subtract a prediction signal (predicted block, prediction sample array) output from the inter prediction unit 221 or the intra prediction unit 222 from an input video signal (original block, original sample array) to generate a residual signal (residual block, residual sample array), and the generated residual signal is transmitted to the conversion unit 232. In this case, as shown in the figure, a unit in the encoding apparatus 200 that subtracts a prediction signal (predicted block, prediction sample array) from an input video signal (original block, original sample array) may be referred to as a subtraction unit 231. The prediction unit may perform prediction on a current block (hereinafter, referred to as a current block) and generate a predicted block including prediction samples for the current block. The prediction unit may determine whether intra prediction or inter prediction is applied on a current block or CU basis. The prediction unit may generate various information related to prediction, such as prediction mode information, and transmit the information to the entropy encoding unit 240, as will be described later in the description of each prediction mode. The prediction information can be encoded by the entropy encoding unit 240 and output in the form of a bitstream.

[0043] The intra prediction unit 222 may predict the current block by referring to samples in the current picture. The referenced samples may be located adjacent to or distant from the current block depending on the prediction mode. Prediction modes in intra prediction may include a plurality of non-directional modes and a plurality of directional modes. The non-directional modes may include, for example, DC mode and planar mode. The directional modes may include, for example, 33 directional prediction modes or 65 directional prediction modes depending on the granularity of the prediction direction. However, this is merely an example, and more or less directional prediction modes may be used depending on the settings. The intra prediction unit 222 may also determine the prediction mode to be applied to the current block using the prediction modes applied to neighboring blocks.

[0044] The inter prediction unit 221 may derive a predicted block for a current block based on a reference block (reference sample array) identified by a motion vector on a reference picture. To reduce the amount of motion information transmitted in inter prediction mode, the motion information may be predicted in units of blocks, sub-blocks, or samples based on the correlation of motion information between neighboring blocks and the current block. The motion information may include a motion vector and a reference picture index. The motion information may further include information on an inter prediction direction (such as L0 prediction, L1 prediction, or Bi prediction). In the case of inter prediction, the neighboring blocks may include spatial neighboring blocks in the current picture and temporal neighboring blocks in the reference picture. The reference picture including the reference block and the reference picture including the temporal neighboring block may be the same or different. The temporal neighboring block may be called a collocated reference block, a collocated CU (col CU), or the like, and the reference picture including the temporal neighboring block may be called a collocated picture (colPic). For example, the inter predictor 221 may construct a motion information candidate list based on neighboring blocks and generate information indicating which candidate is used to derive a motion vector and / or a reference picture index for the current block. Inter prediction may be performed based on various prediction modes, and for example, in the case of a skip mode or a merge mode, the inter predictor 221 may use motion information of neighboring blocks as motion information of the current block. In the case of the skip mode, unlike the merge mode, a residual signal may not be transmitted.In the case of motion vector prediction (MVP) mode, the motion vector of the neighboring block can be used as a motion vector predictor, and the motion vector of the current block can be indicated by signaling the motion vector difference.

[0045] The prediction unit 220 may generate a prediction signal based on various prediction methods, which will be described later. For example, the prediction unit may apply intra prediction or inter prediction for predicting a block, or may simultaneously apply intra prediction and inter prediction. This may be referred to as combined inter and intra prediction (CIIP). The prediction unit may also use an intra block copy (IBC) prediction mode or a palette mode for predicting a block. The IBC prediction mode or palette mode may be used for content image / video coding, such as games, such as screen content coding (SCC). IBC basically performs prediction within a current picture, but may be performed similarly to inter prediction in deriving a reference block within the current picture. That is, IBC may use at least one of the inter prediction techniques described herein. The palette mode may be considered an example of intra coding or intra prediction. When the palette mode is applied, sample values ​​within a picture may be signaled based on information related to a palette table and a palette index.

[0046] The prediction signal generated by the prediction unit (including the inter prediction unit 221 and / or the intra prediction unit 222) may be used to generate a reconstructed signal or a residual signal. The transform unit 232 may generate transform coefficients by applying a transform technique to the residual signal. For example, the transform 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 transform obtained from a graph representing inter-pixel relationship information. CNT refers to a transform obtained based on a prediction signal generated using all previously reconstructed pixels. The transform process may be applied to pixel blocks having the same square size or non-square blocks of variable sizes.

[0047] The quantization unit 233 quantizes the transform coefficients and transmits them to the entropy encoding unit 240. The entropy encoding unit 240 encodes the quantized signal (information about the quantized transform coefficients) and outputs it as a bitstream. The information about the quantized transform coefficients may be referred to as residual information. The quantization unit 233 may rearrange the quantized transform coefficients in a block form into a one-dimensional vector form based on a coefficient scan order, and may generate information about the quantized transform coefficients based on the quantized transform coefficients in the one-dimensional vector form. The entropy encoding unit 240 may perform various encoding methods, such as exponential Golomb, context-adaptive variable length coding (CAVLC), and context-adaptive binary arithmetic coding (CABAC). The entropy encoding unit 240 may encode information required for video / image restoration (e.g., values ​​of syntax elements, etc.) together with or separately from the quantized transform coefficients. The encoded information (e.g., encoded video / image information) may be transmitted or stored in the form of a bitstream in network abstraction layer (NAL) units. The video / image information may further include information on various parameter sets, such as an adaptation parameter set (APS), a picture parameter set (PPS), a sequence parameter set (SPS), or a video parameter set (VPS). The video / image information may also include general constraint information. In this document, 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 above-described encoding procedure and included in the bitstream. The bitstream may be transmitted via a network or stored in a digital storage medium. Here, the network may include a broadcasting network and / or a communication network, and the digital storage medium may include various storage media such as USB, SD, CD, DVD, Blu-ray, HDD, SSD, etc. A transmitter (not shown) for transmitting the signal output from the entropy encoding unit 240 and / or a storage unit (not shown) for storing the signal may be configured as an internal / external element of the encoding apparatus 200, or the transmitter may be included in the entropy encoding unit 240.

[0048] The quantized transform coefficients output from the quantizer 233 may be used to generate a prediction signal. For example, a residual signal (residual block or residual sample) may be reconstructed by applying inverse quantization and inverse transform to the quantized transform coefficients via the inverse quantizer 234 and the inverse transformer 235. The adder 155 may generate a reconstructed signal (reconstructed picture, reconstructed block, reconstructed sample array) by adding the reconstructed residual signal to the prediction signal output from the inter predictor 221 or the intra predictor 222. When there is no residual for the current block, such as when a skip mode is applied, a predicted block may be used as the reconstructed block. The adder 250 may be referred to as a reconstruction unit or a reconstructed block generator. The generated reconstructed signal may be used for intra prediction of the next block to be processed in the current picture, or may be used for inter prediction of the next picture after filtering, as described below.

[0049] Meanwhile, luma mapping with chrominance scaling (LMCS) can be applied during picture encoding and / or restoration.

[0050] The filtering unit 260 may apply filtering to the reconstructed signal to improve subjective / objective image quality. For example, the filtering unit 260 may apply various filtering methods to the reconstructed picture to generate a modified reconstructed picture and store the modified reconstructed picture in the memory 270, specifically, in the DPB of the memory 270. The various filtering methods may include, for example, deblocking filtering, sample adaptive offset (SAO), an adaptive loop filter, a bilateral filter, etc. The filtering unit 260 may generate various information related to filtering and transmit it to the entropy encoding unit 290, as will be described later in the description of each filtering method. The filtering information may be encoded by the entropy encoding unit 290 and output in the form of a bitstream.

[0051] The modified reconstructed picture transmitted to the memory 270 can be used as a reference picture in the inter prediction unit 280. When inter prediction is applied through this, the encoding apparatus can avoid prediction mismatch between the encoding apparatus 200 and the decoding apparatus, and can also improve coding efficiency.

[0052] The DPB of the memory 270 may store a modified reconstructed picture to be used as a reference picture in the inter predictor 221. The memory 270 may store motion information of a block from which motion information in the current picture is derived (or encoded) and / or motion information of a block in an already reconstructed picture. The stored motion information may be transmitted to the inter predictor 221 to be used as motion information of a spatially neighboring block or a temporally neighboring block. The memory 270 may store reconstructed samples of reconstructed blocks in the current picture and transmit them to the intra predictor 222.

[0053] FIG. 3 is a diagram illustrating the configuration of a video / image decoding device to which this document can be applied.

[0054] As shown in FIG. 3, the decoding device 300 may 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 331 and an intra predictor 332. The residual processor 320 may include a dequantizer 321 and an inverse transformer 321. Depending on the embodiment, the entropy decoding unit 310, the residual processor 320, the predictor 330, the adder 340, and the filter 350 may be implemented as a single hardware component (e.g., a decoder chipset or processor). The memory 360 may include a decoded picture buffer (DPB) or may be implemented as a digital storage medium. The hardware components may further include a memory 360 as an internal / external component.

[0055] When a bitstream including video / image information is input, the decoding apparatus 300 can reconstruct an image corresponding to the process in which the video / image information was processed by the encoding apparatus of FIG. 3. For example, the decoding apparatus 300 can derive units / blocks based on block division-related information obtained from the bitstream. The decoding apparatus 300 can perform decoding using a processing unit applied by the encoding apparatus. Therefore, the processing unit for decoding can be, for example, a coding unit, and the coding unit can be divided from a coding tree unit or a maximal coding unit according to a quad tree structure, a binary tree structure, and / or a ternary tree structure. One or more transform units can be derived from the coding unit. The reconstructed image signal decoded and output by the decoding apparatus 300 can be reproduced via a reproduction device.

[0056] The decoding apparatus 300 may receive a signal output from the encoding apparatus of FIG. 3 in the form of a bitstream, and the received signal may be decoded via the entropy decoding unit 310. For example, the entropy decoding unit 310 may parse the bitstream to derive information (e.g., video / video information) necessary for image restoration (or picture restoration). The video / video information may further include information on various parameter sets, such as an adaptation parameter set (APS), a picture parameter set (PPS), a sequence parameter set (SPS), or a video parameter set (VPS). The video / video information may also include general constraint information. The decoding apparatus may further decode pictures based on the information on the parameter sets and / or the general constraint information. Signaled / received information and / or syntax elements, which will be described later in this document, may be decoded via the decoding procedure and obtained from the bitstream. For example, the entropy decoding unit 310 may decode information in a bitstream based on a coding method such as Exponential Golomb coding, CAVLC, or CABAC, and output values ​​of syntax elements required for image restoration and quantized values ​​of transform coefficients related to residuals. More specifically, the CABAC entropy decoding method may receive bins corresponding to each syntax element in the bitstream, determine a context model using information on the syntax element to be decoded, decoding information on neighboring and current blocks, or information on symbols / bins decoded in previous steps, predict the occurrence probability of bins based on the determined context model, and perform arithmetic decoding of the bins to generate symbols corresponding to the values ​​of each syntax element.In this case, after determining a context model, the CABAC entropy decoding method may update the context model using information on the decoded symbol / bin for the context model of the next symbol / bin. Prediction-related information from the information decoded by the entropy decoding unit 310 may be provided to a prediction unit (inter prediction unit 332 and intra prediction unit 331), and residual values ​​entropy-decoded by the entropy decoding unit 310, i.e., quantized transform coefficients and related parameter information, may be input to the residual processing unit 320. The residual processing unit 320 may derive a residual signal (residual block, residual sample, residual sample array). Furthermore, filtering-related information from the information decoded by the entropy decoding unit 310 may be provided to the filtering unit 350. Meanwhile, a receiving unit (not shown) that receives a signal output from the encoding apparatus may be further configured as an internal / external element of the decoding apparatus 300, or the receiving unit may be a component of the entropy decoding unit 310. Meanwhile, the decoding device according to this document may be called a video / image / picture decoding device, and the decoding device may be divided into an information decoder (video / image / picture information decoder) and a sample decoder (video / image / picture sample decoder). The information decoder may include the entropy decoding unit 310, and the sample decoder may include at least one of the inverse quantization unit 321, the inverse transform unit 322, the addition unit 340, the filtering unit 350, the memory 360, the inter prediction unit 332, and the intra prediction unit 331.

[0057] The inverse quantization unit 321 may inverse quantize the quantized transform coefficients and output the transform coefficients. The inverse quantization unit 321 may rearrange the quantized transform coefficients in a two-dimensional block format. In this case, the rearrangement may be performed based on the coefficient scanning order performed in the encoding apparatus. The inverse quantization unit 321 may inverse quantize the quantized transform coefficients using a quantization parameter (e.g., quantization step size information) to obtain transform coefficients.

[0058] The inverse transform unit 322 performs inverse transform on the transform coefficients to obtain a residual signal (residual block, residual sample array).

[0059] The prediction unit may perform prediction on a current block and generate a predicted block including prediction samples for the current block. The prediction unit may determine whether intra prediction or inter prediction is applied to the current block based on information about the prediction output from the entropy decoding unit 310, and may determine a specific intra / inter prediction mode.

[0060] The prediction unit 330 may generate a prediction signal based on various prediction methods, which will be described later. For example, the prediction unit may apply intra prediction or inter prediction for predicting a block, or may simultaneously apply intra prediction and inter prediction. This may be referred to as combined inter and intra prediction (CIIP). The prediction unit may also use an intra block copy (IBC) prediction mode or a palette mode for predicting a block. The IBC prediction mode or palette mode may be used for content video / movie coding, such as games, such as screen content coding (SCC). IBC basically performs prediction within a current picture, but may be performed similarly to inter prediction in that a reference block is derived within the current picture. That is, IBC may use at least one of the inter prediction techniques described herein. The palette mode may be considered an example of intra coding or intra prediction. When the palette mode is applied, information regarding a palette table and a palette index may be included in the video / picture information and signaled.

[0061] The intra prediction unit 331 may predict a current block by referring to samples in a current picture. The referenced samples may be located adjacent to or distant from the current block depending on the prediction mode. Prediction modes in intra prediction may include a plurality of non-directional modes and a plurality of directional modes. The intra prediction unit 331 may also determine a prediction mode to be applied to the current block using prediction modes applied to neighboring blocks.

[0062] The inter prediction unit 332 may derive a predicted block for a current block based on a reference block (reference sample array) identified by a motion vector on a reference picture. To reduce the amount of motion information transmitted in inter prediction mode, the motion information may be predicted in units of blocks, sub-blocks, or samples based on the correlation of motion information between neighboring blocks and the current block. The motion information may include a motion vector and a reference picture index. The motion information may further include information on an inter prediction direction (e.g., L0 prediction, L1 prediction, Bi prediction, etc.). In the case of inter prediction, the neighboring blocks may include spatial neighboring blocks in the current picture and temporal neighboring blocks in the reference picture. For example, the inter prediction unit 332 may construct a motion information candidate list based on the neighboring blocks and derive a motion vector and / or a reference picture index for the current block based on received candidate selection information. Inter prediction may be performed based on various prediction modes, and the prediction information may include information indicating the inter prediction mode for the current block.

[0063] The adder 340 may generate a reconstructed signal (reconstructed picture, reconstructed block, reconstructed sample array) by adding the acquired residual signal to the predicted signal (predicted block, predicted sample array) output from the predictor 330. When there is no residual for the current block, such as when a skip mode is applied, the predicted block may be used as the reconstructed block.

[0064] The adder 340 may be referred to as a reconstruction unit or a reconstruction block generator. The generated reconstruction signal may be used for intra prediction of a next block to be processed in the current picture, may be output after filtering as described below, or may be used for inter prediction of a next picture.

[0065] Meanwhile, LMCS (luma mapping with chroma scaling) can be applied during picture decoding.

[0066] The filtering unit 350 may apply filtering to the reconstructed signal to improve subjective / objective image quality. For example, the filtering unit 350 may apply various filtering methods to the reconstructed picture to generate a modified reconstructed picture, and may transmit the modified reconstructed picture to the memory 60, specifically, to the DPB of the memory 360. The various filtering methods may include, for example, deblocking filtering, sample adaptive offset, an adaptive loop filter, a bilateral filter, etc.

[0067] The (modified) reconstructed picture stored in the DPB of the memory 360 can be used as a reference picture in the inter predictor 331. The memory 360 can store motion information of a block from which motion information in the current picture is derived (or decoded) and / or motion information of a block in an already reconstructed picture. The stored motion information can be transmitted to the inter predictor 331 to be used as motion information of a spatially neighboring block or a temporally neighboring block. The memory 360 can store reconstructed samples of reconstructed blocks in the current picture and transmit them to the intra predictor 332.

[0068] In this specification, the embodiments described for the filtering unit 260, inter prediction unit 221, and intra prediction unit 222 of the encoding device 100 can also be applied identically or correspondingly to the filtering unit 350, inter prediction unit 332, and intra prediction unit 331 of the decoding device 300, respectively.

[0069] As described above, prediction is performed to improve compression efficiency during video coding. Accordingly, a predicted block including predicted samples for a current block, which is a block to be coded, can be generated. Here, the predicted block includes predicted samples in the spatial domain (or pixel domain). The predicted block is derived in the same way by an encoding device and a decoding device. The encoding device can improve image coding efficiency by signaling to a decoding device information (residual information) regarding the residual between the original block and the predicted block, rather than the original sample values ​​of the original block themselves. The decoding device can derive a residual block including residual samples based on the residual information, add the residual block and the predicted block to generate a reconstructed block including reconstructed samples, and generate a reconstructed picture including the reconstructed block.

[0070] The residual information may be generated through a transform and quantization procedure. For example, an encoding apparatus may derive a residual block between the original block and the predicted block, perform a transform procedure on residual samples (residual sample array) included in the residual block to derive transform coefficients, and perform a quantization procedure on the transform coefficients to derive quantized transform coefficients, and then signal the related residual information (via a bitstream) to a decoding apparatus. Here, the residual information may include information such as value information, position information, transform technique, transform kernel, and quantization parameter of the quantized transform coefficients. The decoding apparatus may derive residual samples (or residual blocks) by performing an inverse quantization / inverse transform procedure based on the residual information. The decoding apparatus may generate a reconstructed picture based on the predicted block and the residual block. The encoding apparatus may also derive a residual block by inverse quantizing / inverse transforming the quantized transform coefficients for reference for inter-prediction of a future picture, and generate a reconstructed picture based on the residual block.

[0071] FIG. 4 shows an example of a hierarchical structure for coded data.

[0072] Referring to Figure 4, the coded data can be divided into a VCL (video coding layer) that handles the video / image coding process and itself, and a NAL (Network abstraction layer) that is located between the lower system that stores and transmits the coded video / image data.

[0073] The VCL can generate parameter sets (picture parameter set (PPS), sequence parameter set (SPS), video parameter set (VPS), etc.) corresponding to headers of sequences and pictures, and supplemental enhancement information (SEI) messages additionally required for the video / image coding process. The SEI message is separated from information about the video / image (slice data). The VCL containing information about the video / image consists of slice data and a slice header. Meanwhile, the slice header can be referred to as a tile group header, and the slice data can be referred to as tile group data.

[0074] In NAL, NAL units can be generated by adding header information (NAL unit header) to RBSP (Raw Byte Sequence Payload) generated by VCL. RBSP refers to slice data, parameter sets, SEI messages, etc. generated by VCL. The NAL unit header can include NAL unit type information identified by the RBSP data included in the NAL unit.

[0075] The NAL unit, which is the basic unit of the NAL, serves to map coded video into a bitstream of a lower system such as a file format according to a predetermined standard, a Real-time Transport Protocol (RTP), or a Transport Stream (TS).

[0076] As shown, NAL units can be divided into VCL NAL units and non-VCL NAL units according to the RBSP generated by the VCL. A VCL NAL unit can refer to a NAL unit containing information about a video (slice data), and a non-VCL NAL unit can refer to a NAL unit containing information necessary for decoding a video (parameter set or SEI message).

[0077] The VCL NAL units and non-VCL NAL units can be transmitted over a network with header information according to the data standard of the lower system. For example, the NAL units can be transformed into a data format conforming to a predetermined standard, such as the H.266 / VVC file format, Real-time Transport Protocol (RTP), Transport Stream (TS), etc., and then transmitted over various networks.

[0078] As mentioned above, the NAL unit type of an NAL unit can be identified by the RBSP data structure included in the NAL unit, and information about such NAL unit type can be stored and signaled in the NAL unit header.

[0079] For example, NAL units can be broadly classified into VCL NAL unit types and non-VCL NAL unit types depending on whether they contain information about video (slice data). VCL NAL unit types can be classified according to the nature and type of pictures contained in the VCL NAL unit, and non-VCL NAL unit types can be classified according to the type of parameter set.

[0080] The following is an example of a NAL unit type identified by the type of parameter set included in the non-VCL NAL unit type. The NAL unit type can be identified by the type of parameter set included. For example, the NAL unit type can be identified as any one of an APS (Adaptation Parameter Set) NAL unit, which is the type for NAL units including an APS, a DPS (Decoding Parameter Set) NAL unit, which is the type for NAL units including a DPS, a VPS (Video Parameter Set) NAL unit, which is the type for NAL units including a VPS, an SPS (Sequence Parameter Set) NAL unit, which is the type for NAL units including an SPS, and a PPS (Picture Parameter Set) NAL unit, which is the type for NAL units including a PPS.

[0081] The NAL unit type has syntax information for the NAL unit type, and the syntax information can be stored in a NAL unit header and signaled. For example, the syntax information can be nal_unit_type, and the NAL unit type can be specified by the nal_unit_type value.

[0082] Meanwhile, as described above, one picture may include multiple slices, and one slice may include a slice header and slice data. In this case, one picture header may be added to multiple slices (slice header and slice data set) in one picture. The picture header (picture header syntax) may include information / parameters commonly applicable to the picture. The slice header (slice header syntax) may include information / parameters commonly applicable to the slices. The APS (APS syntax) or PPS (PPS syntax) may include information / parameters commonly applicable to one or more slices or pictures. The SPS (SPS syntax) may include information / parameters commonly applicable to one or more sequences. The VPS (VPS syntax) may include information / parameters commonly applicable to multiple layers. The DPS (DPS syntax) may include information / parameters commonly applicable to the entire video. The DPS may include information / parameters related to concatenation of a coded video sequence (CVS). In this document, the high level syntax (HLS) may include at least one of the APS syntax, PPS syntax, SPS syntax, VPS syntax, DPS syntax, picture header syntax, and slice header syntax.

[0083] In this document, image / video information encoded by an encoding device and a decoding device and signaled in the form of a bitstream may include information included in the slice header, information included in the picture header, information included in the APS, information included in the PPS, information included in the SPS, information included in the VPS, and / or information included in the DPS, as well as intra-picture partitioning-related information, intra / inter prediction information, residual information, in-loop filtering information, etc. In addition, the image / video information may further include information in a NAL unit header.

[0084] FIG. 5 is a diagram illustrating an example of partitioning a picture.

[0085] A picture may be divided into coding tree units (CTUs), and each CTU may correspond to a coding tree block (CTB). A CTU may include a coding tree block for luma samples and two coding tree blocks for corresponding chroma samples. Meanwhile, the maximum allowable size of a CTU for coding and prediction may be different from the maximum allowable size of a CTU for transformation.

[0086] A tile may correspond to a series of CTUs covering a rectangular area of ​​a picture, and a picture may be divided into one or more tile rows and one or more tile columns.

[0087] Meanwhile, a slice can consist of an integer number of complete tiles or an integer number of consecutive complete CTU rows, and two slice modes, including a raster-scan slice mode and a rectangular slice mode, can be supported.

[0088] In raster scan slice mode, a slice can include a series of complete tiles in a tile raster scan of the picture. In rectangular slice mode, a slice can include multiple complete tiles that collectively form a rectangular area of ​​the picture. Or, in rectangular slice mode, a slice can include multiple contiguous CTU rows within a tile that collectively form a rectangular area of ​​the picture. The tiles within a rectangular slice can be scanned in tile raster scan order within the rectangular area corresponding to the slice.

[0089] A subpicture, on the other hand, can contain one or more slices that cover a rectangular area of ​​a picture.

[0090] 5A is a diagram showing an example of dividing a picture into raster scan slices. For example, a picture can be divided into 12 tiles and 3 raster scan slices.

[0091] 5(b) is a diagram showing an example of dividing a picture into rectangular slices. For example, a picture can be divided into 24 tiles (6 tile columns and 4 tile rows) and 9 rectangular slices.

[0092] 5(c) is a diagram showing an example of dividing a picture into tiles and rectangular slices. For example, a picture can be divided into 24 tiles (two tile columns and two tile rows) and four rectangular slices.

[0093] FIG. 6 is a flow diagram illustrating a picture encoding procedure according to one embodiment.

[0094] In one embodiment, the picture partitioning (S600) may be performed by the video partitioning unit 210 of the encoding device, and the picture encoding (S610) may be performed by the entropy encoding unit 240 of the encoding device.

[0095] An encoding apparatus according to an embodiment may derive slices and / or tiles included in a current picture (S600). For example, the encoding apparatus may perform picture partitioning for encoding an input current picture. For example, the encoding apparatus may derive slices and / or tiles included in the current picture. The encoding apparatus may partition the picture into various types taking into account video characteristics and coding efficiency of the current picture, and may generate information indicating a partitioning type having optimal coding efficiency and signal the information to a decoding apparatus.

[0096] An encoding device according to an embodiment may perform encoding on a current picture based on the derived slices and / or tiles (S610). For example, the encoding device may encode video / image information including information about slices and / or tiles and output the encoded video / image information in the form of a bitstream. The output bitstream may be transmitted to a decoding device via a digital storage medium or a network.

[0097] FIG. 7 is a flow diagram illustrating a picture decoding procedure according to one embodiment.

[0098] In one embodiment, the step of obtaining video / image information from the bitstream (S710) and the step of deriving slices and / or tiles within the current picture (S720) can be performed by the entropy decoding unit 310 of the decoding device, and the step of reconstructing the current picture based on the slices and / or tiles can be performed by the addition unit 340 of the decoding device.

[0099] A decoding apparatus according to an embodiment may acquire video / image information from a received bitstream (S710). The video / image information may include an HLS, and the HLS may include slice-related information or tile-related information. The slice-related information may include information identifying one or more slices in a current picture, and the tile-related information may include information identifying one or more tiles in the current picture. The slice-related information or tile-related information may be acquired through various parameter sets, a picture header, and / or a slice header.

[0100] Meanwhile, the current picture may include tiles that include one or more slices or slices that include one or more tiles.

[0101] A decoding apparatus according to an embodiment may derive slices and / or tiles in a current picture based on video / image information including information about slices and / or tiles (S720).

[0102] A decoding apparatus according to an embodiment may reconstruct (decode) a current picture based on slices and / or tiles (S730).

[0103] Meanwhile, as described above, a picture can be divided into sub-pictures, tiles, and slices. Information about sub-pictures can be signaled through an SPS, information about tiles and rectangular slices can be signaled through a PPS, and information about raster-scan slices can be signaled through a slice header.

[0104] For example, the SPS syntax including information about sub-pictures may be as follows:

[0105] [Table 1]

[0106] For example, the PPS syntax including information about tiles and quadrilateral slices may be as follows:

[0107] [Table 2]

[0108] Also, for example, the slice header syntax containing information about a raster-scan slice may be as follows:

[0109] [Table 3]

[0110] Meanwhile, the information about slices and the information about tiles in the current picture may include a flag indicating whether each subpicture in the current picture includes a single slice. The flag may be referred to as, but is not limited to, single_slice_per_subpic_flag or pps_single_slice_per_subpic_flag. Furthermore, the information about subpictures may include a flag indicating whether subpicture information is present. The flag may be referred to as, but is not limited to, subpics_present_flag or sps_subpic_info_present_flag. For example, the information about subpictures may be included in a parameter set (parameter_set). For example, the information about subpictures may be included in an SPS.

[0111] Conventionally, if the value of a flag indicating whether subpicture information is present is 0, the value of a flag indicating whether a subpicture includes a single slice is restricted to 0. In other words, if the value of the flag indicating whether subpicture information is present is 0, it is determined that a subpicture is not available, and the value of the flag indicating whether a subpicture includes a single slice is restricted to 0. However, this condition is very restrictive. For example, even if subpicture information is not present, the current picture can be divided into two or more tiles, and all the tiles can be included in one slice. In this case, the current picture includes a single slice.

[0112] Therefore, one embodiment of this document proposes a solution to remove the restriction that when the value of the flag regarding the presence or absence of sub-picture information is 0, the value of the flag regarding whether the sub-picture includes only one slice is 0. In such a case, the flag regarding whether the sub-picture includes only one slice can indicate that the current picture includes only one slice even when sub-picture information does not exist.

[0113] For example, according to the above embodiment, even if there is no sub-picture information for a coded layer video sequence (CLVS), there may be a flag regarding whether a sub-picture contains a single slice, i.e., even if there is no sub-picture information for a CLVS, the flag regarding whether a sub-picture contains a single slice may have a value of 0 or 1.

[0114] For example, the current picture can include a single slice if the value of the flag regarding the presence or absence of sub-picture information is 0 and the value of the flag regarding whether the sub-picture includes a single slice is 1. That is, if there is no signaled sub-picture and the value of the flag regarding whether the sub-picture includes a single slice is 1, it can be inferred that the number of slices in the picture is 1.

[0115] Also, if the value of the flag regarding the presence or absence of sub-picture information is 0, the number of sub-pictures in the current picture may be 1. For example, if the value of the flag regarding the presence or absence of sub-picture information is 0, the number of sub-pictures present in each of all pictures that refer to the SPS of the video information may be 1.

[0116] Meanwhile, a flag indicating the number of slices included in the current picture may be included in the PPS of the video information. The flag indicating the number of slices included in the current picture may be referred to as, but is not limited to, num_slices_in_pic_minus1 or pps_num_slices_in_pic_minus1. Also, a flag indicating the number of sub-pictures included in the current picture may be included in the SPS of the video information. The flag indicating the number of sub-pictures included in the current picture may be referred to as, but is not limited to, sps_num_subpics_minus1.

[0117] If there is no signaled sub-picture information and the value of the flag regarding whether the sub-picture includes a single slice is 1, it can be inferred that the flag regarding the number of slices included in the current picture has a value of 0. Also, if there is no signaled sub-picture information and the value of the flag regarding whether the sub-picture includes a single slice is 1, it can be inferred that the flag regarding the number of slices included in the current picture and the flag regarding the number of sub-pictures included in the current picture have the same value.

[0118] Also, if there are no sub-pictures signaled and the value of the flag regarding whether the sub-picture contains a single slice is 1, all CTUs in the picture can belong to the single slice contained in the picture.

[0119] The semantics of the syntax elements including a flag indicating whether the sub-picture according to the above embodiment includes a single slice and a flag indicating the number of slices included in the current picture can be shown in the following table.

[0120] [Table 4]

[0121] Referring to the table above, if the value of single_slice_per_subpic_flag, which corresponds to a flag indicating whether a subpicture includes a single slice, is 1, each subpicture may consist of one rectangular slice. If the value of single_slice_per_subpic_flag is 0, each subpicture may consist of one or more rectangular slices. If the value of single_slice_per_subpic_flag is 1, it can be inferred that the value of num_slices_in_pic_minus1, which corresponds to a flag indicating the number of slices included in the current picture, has the same value as SPS_num_subpics_minus1, which corresponds to a flag indicating the number of subpictures included in the current picture.

[0122] Also, if the value of single_slice_per_subpic_flag is 1 and the value of subpics_present_flag, which corresponds to a flag indicating whether subpicture information is present, is 0, a picture that references a PPS can have one slice per picture.

[0123] Meanwhile, the scanning process, which is the procedure for decoding tiles in a picture, can be determined by the following table.

[0124] [Table 5-1]

[0125] [Table 5-2]

[0126] FIG. 8 is a flowchart illustrating the operation of an encoding device according to an embodiment, and FIG. 9 is a block diagram illustrating the configuration of an encoding device according to an embodiment.

[0127] The method disclosed in Fig. 8 may be performed by the encoding apparatus disclosed in Fig. 2 or Fig. 9. S810 in Fig. 9 may be performed by the image dividing unit 210 disclosed in Fig. 2, and S820 may be performed by the entropy encoding unit 240 disclosed in Fig. 2. In addition, the operations of S810 to S820 are based on part of the content described above with reference to Figs. 1 to 7. Therefore, detailed descriptions that overlap with the content described above with reference to Figs. 1 to 7 will be omitted or simplified.

[0128] 8, an encoding apparatus according to an embodiment may derive at least one slice by dividing a current picture (S810). For example, a video dividing unit 210 of the encoding apparatus may generate division information for the current picture based on the at least one slice.

[0129] An encoding apparatus according to an embodiment may encode video information for a current picture based on at least one slice (S810), where the video information may include partition information generated based on the at least one slice.

[0130] For example, the image information may include a first flag indicating whether sub-picture information exists and a second flag indicating whether the sub-picture includes only one slice. For example, based on the first flag and the second flag, it may be determined that the number of slices included in the current picture is one.

[0131] For example, if the value of the first flag regarding the presence or absence of the sub-picture information is 0 and the value of the second flag is 1, it can be determined that the number of slices included in the current picture is one.

[0132] For example, if the value of the first flag regarding the presence or absence of sub-picture information is 0, the number of sub-pictures present in the current picture may be 1.

[0133] For example, the first flag regarding the presence or absence of the sub-picture information may be included in a sequence parameter set (SPS) of the video information.

[0134] For example, a second flag relating to whether the sub-picture includes only one slice can be included in a PPS (Picture Parameter Set) of the video information.

[0135] For example, the video information may include a third flag regarding the number of slices included in the current picture, and the third flag may be included in the PPS of the video information.

[0136] Also, for example, the video information may include a fourth flag regarding the number of sub-pictures included in the current picture, and the fourth flag may be included in an SPS of the video information.

[0137] Also, for example, if the value of the first flag is 0, it can be derived that the number of sub-pictures present in each of all pictures that refer to the SPS of the video information is one.

[0138] Meanwhile, the video information may include prediction information for the current picture, the prediction information may include information on an inter prediction mode or an intra prediction mode to be performed on the current picture, and an encoding apparatus may generate and encode the prediction information for the current picture.

[0139] Meanwhile, the bitstream can be transmitted to the decoding device via a network or a (digital) storage medium, where the network can include a broadcasting network and / or a communication network, and the digital storage medium can include various storage media such as USB, SD, CD, DVD, Blu-ray, HDD, SSD, etc.

[0140] FIG. 10 is a flowchart illustrating the operation of a decoding device according to an embodiment, and FIG. 11 is a block diagram illustrating the configuration of a decoding device according to an embodiment.

[0141] The method disclosed in Figure 10 may be performed by the decoding device disclosed in Figure 3 or Figure 11. Specifically, S1010 and S1020 may be performed by the entropy decoding unit 310 disclosed in Figure 3. Also, the operations of S1010 and S1020 are based on part of the content described above with reference to Figures 1 to 7. Therefore, the description of specific content that overlaps with the content described above with reference to Figures 1 to 7 will be omitted or simplified.

[0142] A decoding apparatus according to an embodiment may acquire video information for a current picture from a bitstream (S1010). For example, an entropy decoding unit 310 of the decoding apparatus may acquire video information including partition information for the current picture from the bitstream. For example, the partition information may include slice information for the current picture. The video information may also include at least a portion of prediction-related information or residual-related information. For example, the prediction-related information may include inter-prediction mode information or inter-prediction type information.

[0143] A decoding apparatus according to an embodiment may perform decoding on a current picture based on video information (S1020). For example, an entropy decoding unit 310 of the decoding apparatus may derive a partition structure of the current picture based on slice information for the current picture.

[0144] For example, the image information may include a first flag indicating whether sub-picture information is present and a second flag indicating whether the sub-picture includes only one slice. For example, based on the first and second flags, the number of slices included in the current picture may be determined to be one.

[0145] For example, if the value of the first flag is 0 and the value of the second flag is 1, the number of slices included in the current picture can be derived to be one.

[0146] For example, if the value of the flag regarding the presence or absence of sub-picture information is 0, the number of sub-pictures present in the current picture may be one.

[0147] For example, the first flag regarding the presence or absence of the sub-picture information may be included in a sequence parameter set (SPS) of the video information.

[0148] For example, a second flag indicating whether the sub-picture includes a single slice may be included in a PPS (Picture Parameter Set) of the video information.

[0149] For example, the video information may include a third flag regarding the number of slices included in the current picture, and the third flag may be included in the PPS of the video information.

[0150] Also, for example, the video information may include a fourth flag regarding the number of sub-pictures included in the current picture, and the flag regarding the number of sub-pictures included in the current picture may be included in an SPS of the video information.

[0151] Also, for example, if the value of the first flag is 0, it can be derived that the number of sub-pictures present in each of all pictures that refer to the SPS of the video information is one.

[0152] In the above-described embodiments, the methods are described with reference to flow charts as a series of steps or blocks, but the embodiments are not limited to the order of the steps, and certain steps may occur in a different order or simultaneously with other steps than those described. Furthermore, those skilled in the art will understand that the steps shown in the flow charts are not exclusive, and other steps may be included, or one or more steps in the flow charts may be deleted without affecting the scope of the embodiments herein.

[0153] The methods according to the embodiments of the present document described above can be implemented in software form, and the encoding device and / or decoding device according to the present document can be included in devices that perform video processing, such as TVs, computers, smartphones, set-top boxes, and display devices.

[0154] In this document, when an embodiment is implemented in software, the method described above may be implemented with modules (processes, functions, etc.) that perform the functions described above. The modules may be stored in memory and executed by a processor. The memory may be internal or external to the processor and may be coupled to the processor in various well-known ways. 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, a memory card, a storage medium, and / or other storage devices. That is, the embodiments described herein may be implemented and executed on a processor, microprocessor, controller, or chip. For example, the functional units illustrated in each drawing may be implemented and executed on a computer, processor, microprocessor, controller, or chip. In this case, information (e.g., information on instructions) or algorithms for implementation may be stored on a digital storage medium.

[0155] In addition, the decoding device and encoding device to which the present disclosure is applied may be included in a multimedia broadcast transmitting / receiving device, a mobile communication terminal, a home cinema video device, a digital cinema video device, a surveillance camera, a video interaction device, a real-time communication device such as video communication, a mobile streaming device, a storage medium, a camcorder, a custom video (VoD) service providing device, an over-the-top (OTT) video (over-the-top) device, an internet streaming service providing device, a three-dimensional (3D) video device, a virtual reality (VR) device, an augmented reality (AR) device, an image telephone video device, a vehicle terminal (e.g., a vehicle terminal (including an autonomous vehicle), an airplane terminal, a ship terminal, etc.), a medical video device, etc., and may be used to process a video signal or a data signal. For example, over-the-top (OTT) video (over-the-top) devices may include a game console, a Blu-ray player, an internet-connected TV, a home theater system, a smartphone, a tablet PC, a digital video recorder (DVR), etc.

[0156] In addition, a processing method to which the present disclosure is applied can be produced in the form of a computer-executable program and stored in a computer-readable recording medium. Multimedia data having a data structure according to the embodiment(s) of this document can also be stored in 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. Examples of the computer-readable recording medium include Blu-ray Discs (BDs), Universal Serial Buses (USBs), ROMs, PROMs, EPROMs, EEPROMs, RAMs, CD-ROMs, magnetic tapes, floppy disks, and optical data storage devices. The computer-readable recording medium also includes media embodied in the form of carrier waves (e.g., transmission via the Internet). A bitstream generated by an encoding method can be stored in a computer-readable recording medium or transmitted via a wired or wireless communication network.

[0157] Furthermore, embodiments of the present disclosure may be embodied in a computer program product with program code, which may be executed on a computer according to the embodiment(s) of this document, and which may be stored on a computer-readable carrier.

[0158] FIG. 12 illustrates an example of a content streaming system to which the disclosures of this document are applicable.

[0159] Referring to FIG. 12, a content streaming system to which the present disclosure is applied can broadly include an encoding server, a streaming server, a web server, a media repository, a user device, and a multimedia input device.

[0160] The encoding server compresses content input from a multimedia input device such as a smartphone, camera, camcorder, etc. into digital data to generate a bitstream and transmits the bitstream to the streaming server. As another example, if a multimedia input device such as a smartphone, camera, camcorder, etc. directly generates a bitstream, the encoding server may be omitted.

[0161] The bitstream may be generated by an encoding method or a bitstream generation method applied to an embodiment of this document, and the streaming server may temporarily store the bitstream during the process of transmitting or receiving the bitstream.

[0162] 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 an intermediary to inform the user of available services. When a user requests a desired service from the web server, the web server transmits the request to the streaming server, which then transmits the multimedia data to the user. In this case, the content streaming system may include a separate control server, which controls commands and responses between devices in the content streaming system.

[0163] The streaming server can receive content from a media repository and / or an encoding server. For example, if content is received from the encoding server, the content can be received in real time. In this case, the streaming server can store the bitstream for a certain period of time to provide a smooth streaming service.

[0164] Examples of the user devices include mobile phones, smartphones, laptop computers, digital broadcasting terminals, personal digital assistants (PDAs), portable multimedia players (PMPs), navigation systems, slate PCs, tablet PCs, ultrabooks, wearable devices (e.g., smartwatches, smart glasses, head-mounted displays (HMDs)), digital TVs, desktop computers, and digital signs.

[0165] Each server in the content streaming system can be operated as a distributed server, in which case data received by each server can be processed in a distributed manner.

[0166] The claims described herein may be combined in various ways. For example, the technical features of the method claims herein may be combined and embodied in an apparatus, and the technical features of the apparatus claims herein may be combined and embodied in a method. Furthermore, the technical features of the method claims herein and the technical features of the apparatus claims herein may be combined and embodied in an apparatus, and the technical features of the method claims herein and the technical features of the apparatus claims herein may be combined and embodied in a method.

Claims

1. A video decoding method performed by a decoding device, comprising: obtaining video information for a current picture from a bitstream; decoding the current picture based on the video information; the video information includes a first flag associated with the presence of sub-picture information and a second flag associated with whether each sub-picture includes a single slice; based on the value of the first flag being equal to 0 and the value of the second flag being equal to 1, the number of slices included in the current picture is derived to be equal to 1; the value of the second flag being equal to 1 indicates that each sub-picture is composed of a single slice; The method, wherein the first flag is included in a sequence parameter set.

2. A video encoding method performed by an encoding device, comprising: deriving at least one slice by dividing a current picture; encoding video information for the current picture based on the at least one slice; the video information includes a first flag associated with the presence of sub-picture information and a second flag associated with whether each sub-picture in the current picture includes a single slice; based on the value of the first flag being equal to 0 and the value of the second flag being equal to 1, the number of slices included in the current picture is derived to be equal to 1; the value of the second flag being equal to 1 indicates that each sub-picture is composed of a single slice; The method, wherein the first flag is included in a sequence parameter set.

3. A method for transmitting data relating to video, comprising: Obtaining a bitstream generated by a method, said method comprising: deriving at least one slice by dividing the current picture; generating the bitstream by encoding video information for the current picture based on the at least one slice; transmitting the data including the bitstream; the video information includes a first flag associated with the presence of sub-picture information and a second flag associated with whether each sub-picture in the current picture includes a single slice; based on the value of the first flag being equal to 0 and the value of the second flag being equal to 1, the number of slices included in the current picture is derived to be equal to 1; the value of the second flag being equal to 1 indicates that each sub-picture is composed of a single slice; A transmission method, wherein the first flag is included in a sequence parameter set.

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