Apparatus for decoding and encoding image and apparatus for transmitting data for image information

Abstract

Disclosed are an apparatus for decoding and encoding an image and an apparatus for transmitting data for image information. An image decoding method performed by a decoding device according to the present document comprises the steps of: deriving a multi-layer output layer set (OLS) index of a target OLS in a list of OLSs; acquiring hypothetical reference decoder (HRD) related information and decoded picture buffer (DPB) related information for a target OLS based on the multi-layer OLS index; and decoding a picture in the target OLS based on the HRD-related information and the DPB-related information, in which the multi-layer OLS is an OLS including a plurality of layers, and the target OLS is one of the multi-layer OLS.

Description

[0001] This application is a divisional application of the invention patent application with the original application number 202180032947.9 (international application number: PCT / KR2021 / 005508, application date: April 30, 2021, invention name: image decoding method and device). Technical Field

[0002] The present disclosure relates to image coding technology, and more particularly, to an image decoding method and apparatus for encoding video information including HRD-related syntax elements and / or DPB-related syntax elements using a multi-layer OLS index of the multi-layer OLS in an image coding system. Background Art

[0003] Recently, in various fields, the demand for high-resolution, high-quality images such as HD (high definition) images and UHD (ultra high definition) images is growing. Because image data has high resolution and high quality, the amount of information or bits to be transmitted increases relative to conventional image data. Therefore, when image data is transmitted using a medium such as a conventional wired / wireless broadband line or stored using an existing storage medium, its transmission cost and storage cost increase.

[0004] Therefore, there is a need for efficient image compression technology for effectively transmitting, storing and reproducing information of high-resolution and high-quality images. Summary of the invention

[0005] Technical Purpose

[0006] The present disclosure provides a method and an apparatus for improving image coding efficiency.

[0007] Another technical object of the present disclosure is to provide a method and apparatus for signaling HRD-related syntax elements and / or DPB-related syntax elements for a multi-layer OLS.

[0008] Technical Solution

[0009] According to an embodiment of the present specification, an image decoding method performed by a decoding device is provided herein. The method may include the following steps: deriving a multi-layer OLS index of a target OLS in a list of a multi-layer output layer set (OLS); obtaining hypothetical reference decoder (HRD) related information and decoded picture buffer (DPB) related information for the target OLS based on the multi-layer OLS index; and decoding a picture in the target OLS based on the HRD related information and the DPB related information, wherein the multi-layer OLS may be an OLS including a plurality of layers, and wherein the target OLS may be one of the multi-layer OLSs.

[0010] According to another embodiment of the present specification, a decoding device for performing image decoding is provided herein. The decoding device may include: an entropy decoder, which derives a multi-layer OLS index of a target OLS in a list of a multi-layer output layer set (OLS), and obtains hypothetical reference decoder (HRD) related information and decoded picture buffer (DPB) related information for the target OLS based on the multi-layer OLS index; and a DPB, which decodes a picture in the target OLS based on the HRD related information and the DPB related information, wherein the multi-layer OLS may be an OLS including a plurality of layers, and wherein the target OLS may be one of the multi-layer OLSs.

[0011] According to another embodiment of the present specification, an image encoding method performed by an encoding device is provided herein. The method may include the following steps: deriving a multi-layer OLS index of a target OLS in a list of a multi-layer output layer set (OLS); generating hypothetical reference decoder (HRD) related information and decoded picture buffer (DPB) related information for the target OLS based on the multi-layer OLS index; and encoding video information including the HRD related information and the DPB related information, wherein the multi-layer OLS may be an OLS including a plurality of layers, and wherein the target OLS may be one of the multi-layer OLSs.

[0012] According to another embodiment of the present specification, a coding device is provided herein. The coding device may include: an entropy encoder, which derives a multi-layer OLS index of a target OLS in a list of a multi-layer output layer set (OLS), generates hypothesized reference decoder (HRD) related information and decoded picture buffer (DPB) related information for the target OLS based on the multi-layer OLS index, and encodes video information including the HRD related information and the DPB related information, wherein the multi-layer OLS may be an OLS including multiple layers, and wherein the target OLS may be one of the multi-layer OLSs.

[0013] According to another embodiment of the present specification, a non-transitory computer-readable storage medium storing a bit stream is provided herein, wherein the bit stream causes a decoding device to perform the following steps: deriving a multi-layer OLS index of a target OLS in a list of a multi-layer output layer set (OLS); obtaining hypothetical reference decoder HRD-related information and decoding picture buffer DPB-related information for the target OLS based on the multi-layer OLS index; and decoding a picture in the target OLS based on the HRD-related information and the DPB-related information, wherein the multi-layer OLS may be an OLS comprising multiple layers, and wherein the target OLS may be one of the multi-layer OLSs.

[0014] Effects of the present disclosure

[0015] According to the present disclosure, signaling of HRD-related information and DPB-related information can be efficiently performed by deriving an index of a list of multi-layer OLSs among all OLSs, and therefore, overall coding efficiency can be enhanced.

[0016] According to the present disclosure, HRD-related information and DPB-related information signaled only for multi-layer OLSs can be prevented from being mapped to an erroneous (or incorrect) OLS by deriving an index of a list of multi-layer OLSs among all OLSs. And, therefore, the overall coding efficiency can be enhanced. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 An example of a video / image encoding device to which the embodiments of the present disclosure are applicable is briefly illustrated.

[0018] Figure 2 is a schematic diagram illustrating a configuration of a video / image encoding device to which an embodiment of the present disclosure can be applied.

[0019] Figure 3 is a schematic diagram illustrating a configuration of a video / image decoding device to which an embodiment of the present disclosure can be applied.

[0020] Figure 4 The image encoding method performed by the encoding device according to the present document is schematically shown.

[0021] Figure 5 A coding device for performing the image coding method according to the present document is schematically shown.

[0022] Figure 6 The following schematically shows an image decoding method performed by a decoding device according to the present document.

[0023] Figure 7 A decoding device for performing the image decoding method according to the present document is schematically shown.

[0024] Figure 8 A structural diagram of a content streaming system to which the present disclosure is applied is illustrated. DETAILED DESCRIPTION

[0025] The present disclosure can be modified in various forms, and its specific embodiments will be described and illustrated in the accompanying drawings. However, these embodiments are not intended to limit the present disclosure. The terms used in the following description are only used to describe specific embodiments and are not intended to limit the present disclosure. The singular expression includes the plural expression as long as it is clearly read differently. Terms such as "including" and "having" are intended to indicate the presence of features, numbers, steps, operations, elements, parts or combinations thereof used in the following description, so it should be understood that there is no possibility of excluding the presence or addition of one or more different features, numbers, steps, operations, elements, parts or combinations thereof.

[0026] In addition, for the purpose of conveniently illustrating different specific functions, the elements in the figures described in the present disclosure are drawn independently, which does not mean that these elements are implemented by independent hardware or independent software. For example, two or more of these elements can be combined to form a single element, or an element can be divided into multiple elements. Without departing from the concept of the present disclosure, embodiments in which elements are combined and / or divided belong to the present disclosure.

[0027] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In addition, throughout the accompanying drawings, like reference numerals are used to indicate like elements, and the same description of like elements will be omitted.

[0028] Figure 1 An example of a video / image encoding device to which an embodiment of the present disclosure can be applied is briefly illustrated.

[0029] Reference Figure 1 The video / image coding system may include a first device (source device) and a second device (receiver). The source device may send coded video / image information or data to the receiving device in the form of a file or stream via a digital storage medium or a network.

[0030] The source device may include a video source, an encoding device, and a transmitter. The receiving device may include a receiver, a decoding device, and a renderer. The encoding device may be referred to as a video / image encoding device, and the decoding device may be referred to as a video / image decoding device. The transmitter may be included in the encoding device. The receiver may be included in the decoding device. The renderer may include a display, and the display may be configured as a separate device or an external component.

[0031] The video source can obtain the video / image by capturing, synthesizing or generating the video / image process. The video source may include a video / image capture device and / or a video / image generation device. The video / image capture device may include, for example, one or more cameras, a video / image archive including previously captured videos / images, etc. The video / image generation device may include, for example, a computer, a tablet computer, and a smart phone, and may (electronically) generate the video / image. For example, a virtual video / image may be generated by a computer, etc. In this case, the video / image capture process may be replaced by a process that generates relevant data.

[0032] The encoding device can encode the input video / image. The encoding device can perform a series of processes such as prediction, transformation and quantization to achieve compression and coding efficiency. The encoded data (encoded video / image information) can be output in the form of a bitstream.

[0033] The transmitter may transmit the encoded image / image information or data output in the form of a bit stream to the receiver of the receiving device in the form of a file or stream through 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 transmitter may include an element for generating a media file in a predetermined file format, and may include an element for transmitting through a broadcast / communication network. The receiver may receive / extract a bit stream and transmit the received bit stream to a decoding device.

[0034] The decoding device may decode the video / image by performing a series of processes such as inverse quantization, inverse transformation, and prediction corresponding to the operations of the encoding device.

[0035] The renderer can render the decoded video / image, and the rendered video / image can be displayed through a display.

[0036] The present disclosure relates to video / image coding. For example, the methods / implementations disclosed in the present disclosure may be applied to methods disclosed in the Versatile Video Coding (VVC), EVC (Basic Video Coding) standard, AOMedia Video 1 (AV1) standard, the second generation audio video coding standard (AVS2), or the next generation video / image coding standard (e.g., H.267 or H.268, etc.).

[0037] The present disclosure proposes various embodiments of video / image encoding, and unless otherwise mentioned, these embodiments may be performed in combination with each other.

[0038] In the present disclosure, a video may refer to a series of images over time. A picture generally refers to a unit representing a picture in a specific time region, and a sub-picture / slice / tile is a unit that constitutes a part of a picture when encoded. A sub-picture / slice / tile may include one or more coding tree units (CTUs). A picture may be composed of one or more sub-pictures / slices / tiles. A picture may be composed of one or more tile groups. A tile group may include one or more tiles. A brick may represent a rectangular area of ​​a CTU row within a tile in a picture. A tile may be divided into a plurality of bricks, each of which is composed of one or more CTU rows within a tile. A tile that is not divided into a plurality of bricks may also be referred to as a brick. Brick scanning is a specific ordering of CTUs of the following segmented pictures: sorting CTUs by CTU raster scanning in bricks, continuously sorting bricks within tiles by raster scanning of bricks of tiles, and continuously sorting tiles in a picture by raster scanning of tiles of pictures. In addition, a sub-picture may represent a rectangular area of ​​one or more slices within a picture. That is, a sub-picture contains one or more slices that together cover a rectangular area of ​​a picture. A tile is a rectangular area of ​​a CTU within a specific tile column and a specific tile row in a picture. A tile column is a rectangular area of ​​a CTU whose height is equal to the height of the picture and whose width is specified by a syntax element in a picture parameter set. A tile row is a rectangular area of ​​a CTU whose height is specified by a syntax element in a picture parameter set and whose width is equal to the width of the picture. Tile scanning is a specific order sorting of CTUs of a partitioned picture as follows: CTUs are sorted continuously by a raster scan of CTUs in tiles, and tiles in a picture are sorted continuously by a raster scan of tiles of a picture. A slice includes an integer number of bricks of a picture that can be exclusively contained in a single NAL unit. A slice may consist of either a plurality of complete tiles or a continuous sequence of complete bricks of only one tile. In the present disclosure, tile groups and slices may be used interchangeably. For example, in the present disclosure, a tile group / tile group header may be referred to as a slice / slice header.

[0039] A pixel or a pel may refer to the smallest unit constituting a picture (or image). In addition, a "sample" may be used as a term corresponding to a pixel. A sample may generally represent a pixel or a pixel value, may represent only a pixel / pixel value of a luminance component, or may represent only a pixel / pixel value of a chrominance component.

[0040] 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 the area. A unit may include a luminance block and two chrominance (e.g., cb, cr) blocks. In some cases, a unit may be used interchangeably with terms such as a block or an area. In general, an M×N block may include M columns and N rows of samples (or sample arrays) or a set (or array) of transform coefficients.

[0041] In this specification, "A or B" may mean "only A", "only B", or "both A and B". In other words, in this specification, "A or B" may be interpreted as "A and / or B". For example, "A, B or C" herein means "only A", "only B", "only C", or "any one and any combination of A, B, and C".

[0042] 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".

[0043] In the present specification, "at least one of A and B" may mean "only A", "only B", or "both A and B". In addition, in the present specification, the expression "at least one of A or B" or "at least one of A and / or B" may be interpreted as being the same as "at least one of A and B".

[0044] In addition, in the present specification, "at least one of A, B, and C" means "only A", "only B", "only C", or "any combination of A, B, and C". In addition, "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".

[0045] In addition, brackets used in the present specification may mean "for example". Specifically, when "prediction (intra-frame prediction)" is indicated, "intra-frame prediction" may be proposed as an example of "prediction". In other words, "prediction" in the present specification is not limited to "intra-frame prediction", and "intra-frame prediction" may be proposed as an example of "prediction". In addition, even when "prediction (ie, intra-frame prediction)" is indicated, "intra-frame prediction" may be proposed as an example of "prediction".

[0046] In this specification, technical features described individually in one drawing may be implemented individually or may be implemented simultaneously.

[0047] The following figures are created to illustrate specific examples of this specification. Since the names of specific devices or the names of specific signals / messages / fields described in the figures are provided by way of example, the technical features of this specification are not limited to the specific names used in the following figures.

[0048] Figure 2 is a schematic diagram illustrating a configuration of a video / image encoding device to which an embodiment of the present disclosure can be applied. Hereinafter, a video encoding device may include an image encoding device.

[0049] Reference Figure 2 , the encoding device 200 includes an image segmenter 210, a predictor 220, a residual processor 230 and an entropy encoder 240, an adder 250, a filter 260 and a memory 270. The predictor 220 may include an inter-frame predictor 221 and an intra-frame predictor 222. The residual processor 230 may include a transformer 232, a quantizer 233, an inverse quantizer 234 and an inverse transformer 235. The residual processor 230 may also include a subtractor 231. The adder 250 may be called a reconstructor or a reconstructed block generator. According to an embodiment, the image segmenter 210, the predictor 220, the residual processor 230, the entropy encoder 240, the adder 250 and the filter 260 may be composed of at least one hardware component (e.g., an encoder chipset or processor). In addition, the memory 270 may include a decoded picture buffer (DPB) or may be composed of a digital storage medium. The hardware component may also include a memory 270 as an internal / external component.

[0050] The image divider 210 may divide the input image (or picture or frame) input to the encoding device 200 into one or more processors. For example, the processor may be referred to as a coding unit (CU). In this case, the coding unit may be recursively divided from a coding tree unit (CTU) or a maximum coding unit (LCU) according to a quadtree binary tree ternary tree (QTBTTT) structure. For example, a coding unit may be divided into a plurality of coding units with a deeper depth based on a quadtree structure, a binary tree structure, and / or a ternary structure. In this case, for example, a quadtree structure may be applied first, and then a binary tree structure and / or a ternary structure may be applied. Alternatively, a binary tree structure may be applied first. The encoding process according to the present disclosure may be performed based on a final coding unit that is no longer divided. In this case, the maximum coding unit may be used as the final coding unit based on coding efficiency according to image characteristics, or if necessary, the coding unit may be recursively divided into coding units with a deeper depth and a coding unit with an optimal size may be used as the final coding unit. Here, the encoding process may include a process of prediction, transformation, and reconstruction, which will be described later. As another example, the processor may further include a prediction unit (PU) or a transform unit (TU). In this case, the prediction unit and the transform unit may be separated or partitioned from the above-mentioned final coding unit. The prediction unit may be a unit for sample prediction, and the transform unit may be a unit for deriving a transform coefficient and / or a unit for deriving a residual signal from the transform coefficient.

[0051] In some cases, a unit may be used interchangeably with terms such as a block or region. In general, an M×N block may represent a set of samples or transform coefficients consisting of M columns and N rows. A sample may generally represent a pixel or a pixel value, may represent a pixel / pixel value of a luminance component only, or may represent a pixel / pixel value of a chrominance component only. A sample may be used as a term corresponding to a picture (or image) of a pixel or a picture element.

[0052] In the encoding device 200, the prediction signal (prediction block, prediction sample array) output from the inter predictor 221 or the intra predictor 222 is subtracted from the input image signal (original block, original sample array) to generate a residual signal (residual block, residual sample array) and the generated residual signal is sent to the transformer 232. In this case, as shown in the figure, the unit for subtracting the prediction signal (prediction block, prediction sample array) from the input image signal (original block, original sample array) in the encoding device 200 can be called a subtractor 231. The predictor can perform prediction on the block to be processed (hereinafter referred to as the current block) and generate a prediction block including the prediction samples of the current block. The predictor can determine whether to apply intra prediction or inter prediction based on the current block or CU. As described later in the description of each prediction mode, the predictor can generate various information related to the prediction, such as prediction mode information, and send the generated information to the entropy encoder 240. The information about the prediction can be encoded in the entropy encoder 240 and output in the form of a bit stream.

[0053] The intra-frame predictor 222 can predict the current block by referring to samples in the current picture. Depending on the prediction mode, the referenced sample can be located near the current block, or can be far away from the current block. In intra-frame prediction, the prediction mode may include multiple non-directional modes and multiple directional modes. The non-directional mode may include, for example, a DC mode and a plane mode. Depending on the level of detail of the prediction direction, the directional mode may include, for example, 33 directional prediction modes or 65 directional prediction modes. However, this is only an example, and more or fewer directional prediction modes may be used depending on the setting. The intra-frame predictor 222 may determine the prediction mode applied to the current block by using the prediction mode applied to the neighboring blocks.

[0054] The inter-frame predictor 221 may derive a prediction block of the current block based on a reference block (reference sample array) specified by a motion vector on a reference picture. Here, in order to reduce the amount of motion information sent in the inter-frame 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 also include inter-frame prediction direction (L0 prediction, L1 prediction, Bi prediction, etc.) information. In the case of inter-frame prediction, the neighboring blocks may include spatial neighboring blocks present in the current picture and temporal neighboring blocks present 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 referred to as a collocated reference block, a co-located CU (colCU), etc., and the reference picture including the temporal neighboring block may be referred to as a collocated picture (colPic). For example, the inter-frame predictor 221 may configure a motion information candidate list based on neighboring blocks, and generate information indicating which candidate is used to derive the motion vector and / or reference picture index of the current block. Inter-frame prediction may be performed based on various prediction modes. For example, in the case of skip mode and merge mode, the inter-frame predictor 221 may use the motion information of the neighboring block as the motion information of the current block. In skip mode, unlike 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 may be used as a motion vector predictor, and the motion vector of the current block may be indicated by signaling a motion vector difference.

[0055] The predictor 220 may generate a prediction signal based on various prediction methods described below. For example, the predictor may not only apply intra prediction or inter prediction to predict a block, but may also apply both intra prediction and inter prediction at the same time. This may be referred to as intra-frame combined prediction (CIIP). In addition, the predictor may predict a block based on an intra-block copy (IBC) prediction mode or a palette mode. The IBC prediction mode or the palette mode may be used for content image / video encoding of games, etc., such as screen content coding (SCC). IBC basically performs prediction in the current picture, but may be performed similarly to inter prediction because the reference block is derived in the current picture. That is, IBC may use at least one of the inter prediction techniques described in the present disclosure. The palette mode may be considered as an example of intra coding or intra prediction. When the palette mode is applied, the sample values ​​within the picture may be signaled based on information about the palette table and the palette index.

[0056] The prediction signal generated by the predictor (including the inter-frame predictor 221 and / or the intra-frame predictor 222) can be used to generate a reconstruction signal or to generate a residual signal. The transformer 232 can generate a transform coefficient 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-loève transform (KLT), a graph-based transform (GBT), or a conditional nonlinear transform (CNT). Here, GBT represents a transform obtained from a graph when the relationship information between pixels is represented by a graph. CNT refers to a transform generated based on a prediction signal generated using all previously reconstructed pixels. In addition, the transform process can be applied to square pixel blocks of the same size, or can be applied to blocks of variable size rather than square.

[0057] The quantizer 233 may quantize the transform coefficients and send them to the entropy encoder 240, and the entropy encoder 240 may encode the quantized signal (information about the quantized transform coefficients) and output a bitstream. Information about the quantized transform coefficients may be referred to as residual information. The quantizer 233 may rearrange the block type quantized transform coefficients into a one-dimensional vector form based on the coefficient scanning order, and generate information about the quantized transform coefficients based on the quantized transform coefficients in the one-dimensional vector form. Information about the transform coefficients may be generated. The entropy encoder 240 may perform various encoding methods, such as, for example, exponential Golomb, context adaptive variable length coding (CAVLC), context adaptive binary arithmetic coding (CABAC), etc. The entropy encoder 240 may encode information required for video / image reconstruction (e.g., values ​​of syntax elements, etc.) other than the quantized transform coefficients together or separately. Encoded information (e.g., encoded video / image information) may be transmitted or stored in units of NAL (network abstraction layer) in the form of a bitstream. The video / image information may also include information about various parameter sets such as an adaptive parameter set (APS), a picture parameter set (PPS), a sequence parameter set (SPS), or a video parameter set (VPS). In addition, the video / image information may also include general constraint information. In the present disclosure, information and / or syntax elements sent / signaled from an encoding device to a decoding device may be included in the video / image information. The video / image information may be encoded and included in a bitstream through the above-mentioned encoding process. The bitstream may be sent through a network, or may be stored in a digital storage medium. The network may include a broadcast 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) that sends a signal output from the entropy encoder 240 and / or a storage unit (not shown) that stores the signal may be included as an internal / external element of the encoding device 200, and alternatively, the transmitter may be included in the entropy encoder 240.

[0058] The quantized transform coefficients output from the quantizer 233 can be used to generate a prediction signal. For example, the residual signal (residual block or residual sample) can be reconstructed by applying inverse quantization and inverse transformation to the quantized transform coefficients using the inverse quantizer 234 and the inverse transformer 235. The adder 250 adds the reconstructed residual signal to the prediction signal output from the inter-frame predictor 221 or the intra-frame predictor 222 to generate a reconstructed signal (reconstructed picture, reconstructed block, reconstructed sample array). If the block to be processed has no residual (such as the case where the skip mode is applied), the prediction block can be used as a reconstructed block. The adder 250 can be called a reconstructor or a reconstructed block generator. The generated reconstructed signal can be used for intra-frame prediction of the next block to be processed in the current picture, and can be used for inter-frame prediction of the next picture by filtering as described below.

[0059] Furthermore, during picture encoding and / or reconstruction, luma mapping and chroma scaling (LMCS) may be applied.

[0060] The filter 260 can improve the subjective / objective image quality by applying filtering to the reconstructed signal. For example, the filter 260 can generate a modified reconstructed picture by applying various filtering methods to the reconstructed picture, and store the modified reconstructed picture in the memory 270 (specifically, the DPB of the memory 270). Various filtering methods may include, for example, deblocking filtering, sample adaptive offset, adaptive loop filter, bilateral filter, etc. The filter 260 can generate various information related to filtering, and send the generated information to the entropy encoder 240, as described later in the description of various filtering methods. The information related to filtering can be encoded by the entropy encoder 240 and output in the form of a bit stream.

[0061] The modified reconstructed picture sent to the memory 270 may be used as a reference picture in the inter-frame predictor 221. When inter-frame prediction is applied by the encoding device, prediction mismatch between the encoding device 200 and the decoding device may be avoided, and encoding efficiency may be improved.

[0062] The DPB of the memory 270 may store a modified reconstructed picture used as a reference picture in the inter-frame 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 reconstructed block in the picture. The stored motion information may be sent to the inter-frame predictor 221 and used as motion information of a spatially adjacent block or motion information of a temporally adjacent block. The memory 270 may store reconstructed samples of a reconstructed block in the current picture and may transmit the reconstructed samples to the intra-frame predictor 222.

[0063] Figure 3 is a schematic diagram illustrating a configuration of a video / image decoding device to which an embodiment of the present disclosure can be applied.

[0064] Reference Figure 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-frame predictor 332 and an intra-frame predictor 331. The residual processor 320 may include an inverse quantizer 321 and an inverse transformer 322. According to an embodiment, the entropy decoder 310, the residual processor 320, the predictor 330, the adder 340, and the filter 350 may be composed of hardware components (e.g., a decoder chipset or a processor). In addition, the memory 360 may include a decoded picture buffer (DPB), or may be composed of a digital storage medium. The hardware components may also include a memory 360 as an internal / external component.

[0065] When a bit stream including video / image information is input, the decoding device 300 can be used with Figure 2 The image is reconstructed correspondingly to the processing of the video / image information in the encoding device. For example, the decoding device 300 can derive the unit / block based on the block segmentation related information obtained from the bit stream. The decoding device 300 can perform decoding using a processor applied in the encoding device. Therefore, the decoding processor can be, for example, a coding unit, and the coding unit can be segmented from the coding tree unit or the maximum coding unit according to a quadtree 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 device 300 can be reproduced by a reproduction device.

[0066] The decoding device 300 may receive the bit stream from Figure 2The received signal can be decoded by the entropy decoder 310. For example, the entropy decoder 310 can parse the bitstream to derive information (e.g., video / image information) required for image reconstruction (or picture reconstruction). The video / image information may also include information about various parameter sets such as an adaptive parameter set (APS), a picture parameter set (PPS), a sequence parameter set (SPS), or a video parameter set (VPS). In addition, the video / image information may also include general constraint information. The decoding device may also decode the picture based on the information about the parameter set and / or the general constraint information. The signaled / received information and / or syntax elements described later in this disclosure may be decoded by a decoding process and obtained from the bitstream. For example, the entropy decoder 310 decodes the information in the bitstream based on a coding method such as exponential Golomb coding, CAVLC, or CABAC, and outputs the syntax elements required for image reconstruction and the quantized values ​​of the transform coefficients of the residual. More specifically, the CABAC entropy decoding method can receive a bin corresponding to each syntax element in the bitstream, use the decoding target syntax element information, the decoding information of the decoding target block, or the information of the symbol / bin decoded in the previous stage to determine the context model, and arithmetically decode the bin by predicting the probability of occurrence of the bin according to the determined context model, and generate a symbol corresponding to the value of each syntax element. In this case, after determining the context model, the CABAC entropy decoding method can update the context model by using the information of the decoded symbol / bin for the context model of the next symbol / bin. The information related to prediction among the information decoded by the entropy decoder 310 can be provided to the predictor (inter-frame predictor 332 and intra-frame predictor 331), and the residual value (that is, quantized transform coefficients and related parameter information) for which entropy decoding is performed in the entropy decoder 310 can be input to the residual processor 320. The residual processor 320 can derive a residual signal (residual block, residual sample, residual sample array). In addition, the information about filtering among the information decoded by the entropy decoder 310 can be provided to the filter 350. In addition, a receiver (not shown) for receiving a signal output from the encoding device may be further configured as an internal / external element of the decoding device 300, or the receiver may be a component of the entropy decoder 310. In addition, the decoding device according to the present disclosure may be referred to as a video / image / picture decoding device, and the decoding device may be classified 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 decoder 310, and the sample decoder may include at least one of the inverse quantizer 321, the inverse transformer 322, the adder 340, the filter 350, the memory 360, the inter-frame predictor 332, and the intra-frame predictor 331.

[0067] The inverse quantizer 321 may inverse quantize the quantized transform coefficients and output the transform coefficients. The inverse quantizer 321 may rearrange the quantized transform coefficients in the form of two-dimensional blocks. In this case, the rearrangement may be performed based on the coefficient scanning order performed in the encoding device. The inverse quantizer 321 may inverse quantize the quantized transform coefficients by using a quantization parameter (e.g., quantization step size information) and obtain the transform coefficients.

[0068] The inverse transformer 322 inversely transforms the transform coefficients to obtain a residual signal (residual block, residual sample array).

[0069] The predictor may perform prediction on the current block and generate a prediction block including prediction samples of the current block. The predictor may determine whether to apply intra prediction or inter prediction to the current block based on information on prediction output from the entropy decoder 310, and may determine a specific intra / inter prediction mode.

[0070] The predictor 330 may generate a prediction signal based on various prediction methods described below. For example, the predictor may not only apply intra prediction or inter prediction to predict a block, but may also apply intra prediction and inter prediction at the same time. This may be referred to as combined inter and intra prediction (CIIP). In addition, the predictor may predict a block based on an intra block copy (IBC) prediction mode or a palette mode. The IBC prediction mode or the palette mode may be used for content image / video encoding of games, etc., such as screen content coding (SCC). IBC basically performs prediction in the current picture, but may be performed similarly to inter prediction because a reference block is derived in the current picture. That is, IBC may use at least one of the inter prediction techniques described in the present disclosure. The palette mode may be considered an example of intra coding or intra prediction. When the palette mode is applied, the sample values ​​within the picture may be signaled based on information about the palette table and the palette index.

[0071] The intra-frame predictor 331 can predict the current block by referring to samples in the current picture. Depending on the prediction mode, the referenced sample can be located near the current block, or can be far away from the current block. In intra-frame prediction, the prediction mode can include multiple non-directional modes and multiple directional modes. The intra-frame predictor 331 can determine the prediction mode applied to the current block by using the prediction mode applied to the neighboring block.

[0072] The inter-frame predictor 332 may derive a prediction block of the current block based on a reference block (reference sample array) specified by a motion vector on a reference picture. In this case, in order to reduce the amount of motion information sent in the inter-frame prediction mode, the motion information may be predicted in units of blocks, sub-blocks, or samples based on the correlation of the motion information between the neighboring blocks and the current block. The motion information may include a motion vector and a reference picture index. The motion information may also include inter-frame prediction direction (L0 prediction, L1 prediction, Bi prediction, etc.) information. In the case of inter-frame prediction, the neighboring blocks may include spatial neighboring blocks present in the current picture and temporal neighboring blocks present in the reference picture. For example, the inter-frame predictor 332 may configure a motion information candidate list based on the neighboring blocks, and derive a motion vector and / or a reference picture index of the current block based on the received candidate selection information. Inter-frame prediction may be performed based on various prediction modes, and information about the prediction may include information indicating a mode of inter-frame prediction for the current block.

[0073] The adder 340 can generate a reconstructed signal (reconstructed picture, reconstructed block, reconstructed sample array) by adding the obtained residual signal to the prediction signal (prediction block, prediction sample array) output from the predictor (including the inter-frame predictor 332 and / or the intra-frame predictor 331). If the block to be processed has no residual (for example, when the skip mode is applied), the prediction block can be used as the reconstructed block.

[0074] The adder 340 may be referred to as a reconstructor 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, may be output through filtering as described below, or may be used for inter prediction of the next picture.

[0075] In addition, luma mapping and chroma scaling (LMCS) can be applied during picture decoding.

[0076] The filter 350 can improve the subjective / objective image quality by applying filtering to the reconstructed signal. For example, the filter 350 can generate a modified reconstructed picture by applying various filtering methods to the reconstructed picture, and store the modified reconstructed picture in the memory 360 (specifically, the DPB of the memory 360). Various filtering methods may include, for example, deblocking filtering, sample adaptive offset, adaptive loop filter, bilateral filter, etc.

[0077] The (modified) reconstructed picture stored in the DPB of the memory 360 can be used as a reference picture in the inter-frame predictor 332. The memory 360 can store the motion information of the block from which the motion information in the current picture is derived (or decoded) and / or the motion information of the reconstructed block in the picture. The stored motion information can be sent to the inter-frame predictor 332 to be used as the motion information of the spatial neighboring block or the motion information of the temporal neighboring block. The memory 360 can store the reconstructed samples of the reconstructed block in the current picture, and can transmit the reconstructed samples to the intra-frame predictor 331.

[0078] In the present disclosure, the embodiments described in the filter 260, the inter-frame predictor 221, and the intra-frame predictor 222 of the encoding device 200 may be the same as the filter 350, the inter-frame predictor 332, and the intra-frame predictor 331 of the decoding device 300 or may be respectively applied to correspond to the filter 350, the inter-frame predictor 332, and the intra-frame predictor 331 of the decoding device 300. The same contents may also be applied to the inter-frame predictor 332 and the intra-frame predictor 331.

[0079] In the present disclosure, at least one of quantization / inverse quantization and / or transform / inverse transform may be omitted. When quantization / inverse quantization is omitted, the quantized transform coefficient may be referred to as a transform coefficient. When transform / inverse transform is omitted, the transform coefficient may be referred to as a coefficient or a residual coefficient, or may still be referred to as a transform coefficient for the sake of uniformity of expression.

[0080] In the present disclosure, the quantized transform coefficient and the transform coefficient may be referred to as a transform coefficient and a scaled transform coefficient, respectively. In this case, the residual information may include information about the transform coefficient, and the information about the transform coefficient may be signaled by a residual coding syntax. The transform coefficient may be derived based on the residual information (or information about the transform coefficient), and the scaled transform coefficient may be derived by inversely transforming (scaling) the transform coefficient. The residual sample may be derived based on inversely transforming (transforming) the scaled transform coefficient. This may also be applied / expressed in other parts of the present disclosure.

[0081] In addition, the video / image information may include information about a hypothetical reference decoder (HRD) of an output layer set (OLS) and / or information about a decoded picture buffer (DPB). For example, the video / image information may include a video parameter set (VPS), and the VPS may be a parameter set for conveying (or transmitting) information about the DPB and / or information about the HRD.

[0082] For example, information about the DPB and / or information about the HRD may be signaled for each OLS. Herein, the HRD may be a decoder model that specifies an assumption that a network abstraction layer (NAL) unit stream or a byte stream variability constraint that may be generated by the encoding process is consistent with the HRD. When the HRD is present, the information about the HRD may be included in the VPS or the sequence parameter set (SPS). In addition, the information about the DPB may be included in the VPS or the sequence parameter set (SPS), as shown below.

[0083] [Table 1]

[0084]

[0085] For example, the above-mentioned Table 1 may indicate a video parameter set (VPS) including a signaled syntax element for a DPB parameter and / or a syntax element for an HRD parameter.

[0086] The semantics for the syntax elements shown in Table 1 above may be as follows.

[0087] [Table 2]

[0088]

[0089] [Table 3]

[0090]

[0091]

[0092]

[0093]

[0094]

[0095] For example, the variable NumLayersInOls[i] specifying the number of layers in the i-th OLS, the variable LayerIdInOls[i][j] specifying the nuh_layer_id value of the j-th layer in the i-th OLS, and the variable NumMultiLayerOlss specifying the number of multi-layer OLSs (i.e., OLSs including two or more layers) can be derived as shown in Table 2 above.

[0096] In addition, for example, referring to Table 3, when the syntax element vps_num_dpb_params_minus1 exists, the syntax element vps_num_dpb_params_minus1 may indicate the number of dpb_parameters() syntax structures of the VPS. The vps_num_dpb_params_minus1 value may be in the range of 0 to NumMultiLayerOlss-1.

[0097] For example, when the vps_each_layer_is_an_ols_flag value is equal to 1, the variable VpsNumDpbParams indicating the number of dpb_parameters() syntax structures of the VPS may be inferred to be equal to 0, and when the vps_each_layer_is_an_ols_flag value is not equal to 0, the variable VpsNumDpbParams may be inferred to be equal to vps_num_dpb_params_minus1+1.

[0098] Additionally, for example, the syntax element vps_sublayer_dpb_params_present_flag may be used to control the presence of the syntax elements max_dec_pic_buffering_minus1[], max_num_reorder_pics[], and max_latency_increase_plus1[] in the dpb_parameters() syntax structure within the VPS. Additionally, if the syntax element vps_sublayer_dpb_params_present_flag is not present, the value of the syntax element vps_sublayer_dpb_params_present_flag may be inferred to be equal to 0.

[0099] Additionally, for example, the syntax element vps_dpb_max_temporal_id[i] may indicate the TemporalId of the highest sublayer representation, where the DPB parameters may be present in the i-th dpb_parameters() syntax structure within the VPS. The vps_dpb_max_temporal_id[i] value should be in the range of 0 to vps_max_sublayers_minus1. When not present, the vps_dpb_max_temporal_id[i] value is inferred to be equal to vps_max_sublayers_minus1.

[0100] In addition, for example, the syntax element vps_ols_dpb_pic_width[i] may indicate the width of each picture storage buffer of the i-th multi-layer OLS in units of luma samples.

[0101] In addition, for example, the syntax element vps_ols_dpb_pic_height[i] may indicate the height of each picture storage buffer of the i-th multi-layer OLS in units of luma samples.

[0102] Additionally, for example, the syntax element vps_ols_dpb_chroma_format[i] may indicate the maximum allowable value of sps_chroma_format_idc of all SPSs referenced by the CLVS within the CVS for the i-th multi-layer OLS.

[0103] Additionally, for example, the syntax element vps_ols_dpb_bitdepth_minus8[i] may indicate a maximum allowable value of sps_bit_depth_minus8 for all SPSs referenced by a CLVS within a CVS for an i-th multi-layer OLS.

[0104] In addition, for example, the syntax element vps_ols_dpb_params_idx[i] may indicate the index of the dpb_parameters() syntax structure applied to the i-th OLS. The index may be the index of the dpb_parameters() syntax structure of the VPS. That is, the syntax element vps_ols_dpb_params_idx[i] may indicate the index of the dpb_parameters() syntax structure applied to the i-th OLS among the multiple dpb_parameters() syntax structures of the VPS. The vps_ols_dpb_params_idx[i] value may be in the range of 0 to VpsNumDpbParams-1.

[0105] Herein, when the syntax element vps_ols_dpb_params_idx[i] is not present, the value of the syntax element vps_ols_dpb_params_idx[i] may be inferred as follows: For example, if VpsNumDpbParams is equal to 1, the vps_ols_dpb_params_idx[i] value may be inferred to be equal to 0, otherwise (i.e., when VpsNumDpbParams is greater than 1 and equal to NumMultiLayerOlss), the vps_ols_dpb_params_idx[i] value may be inferred to be equal to i.

[0106] Additionally, for example, for a single-layer OLS, an applicable dpb_parameters() syntax structure may be present in the SPS referenced by the layers of the OLS. For i in the range from 0 to NumMultiLayerOlss-1 (inclusive), each dpb_parameters() syntax structure of a VPS may be referenced by at least one vps_ols_dpb_params_idx[i] value.

[0107] In addition, for example, the syntax element vps_general_hrd_params_present_flag may indicate whether the VPS includes a general_hrd_parameters() syntax structure and other HRD parameters. For example, if the vps_general_hrd_params_present_flag value is equal to 1, this may indicate that the VPS includes a general_hrd_parameters() syntax structure and other HRD parameters. And, if the vps_general_hrd_params_present_flag value is equal to 0, this may indicate that the VPS does not include a general_hrd_parameters() syntax structure or other HRD parameters. When the syntax element vps_general_hrd_params_present_flag is not present, the value of the syntax element vps_general_hrd_params_present_flag may be inferred to be equal to 0.

[0108] When the value of NumLayersInOls[i] is equal to 1, a general_hrd_parameters() syntax structure and an ols_hrd_parameters() syntax structure applied to the i-th OLS may exist in the SPS referenced by the layers of the i-th OLS.

[0109] In addition, for example, the syntax element vps_sublayer_cpb_params_present_flag may indicate whether a sublayer represented HRD parameter having a TemporalId range from 0 to hrd_max_tid[i] (including the end value) is included in the i-th ols_hrd_parameters() syntax structure of the VPS. For example, if the vps_sublayer_cpb_params_present_flag value is equal to 1, this may indicate that a sublayer represented HRD parameter having a TemporalId range from 0 to vps_hrd_max_tid[i] (including the end value) is included in the i-th ols_hrd_parameters() syntax structure of the VPS. And, if the vps_sublayer_cpb_params_present_flag value is equal to 0, this may indicate that only HRD parameters represented by the sublayer with TemporalId equal to vps_hrd_max_tid[i] are included in the i-th ols_hrd_parameters() syntax structure of the VPS. When vps_max_sublayers_minus1 is equal to 0, the vps_sublayer_cpb_params_present_flag value may be inferred to be equal to 0.

[0110] When the vps_sublayer_cpb_params_present_flag value is equal to 0, the HRD parameters of the sublayer representation with a TemporalId ranging from 0 to hrd_max_tid[i] (inclusive) can be inferred to be equal to the sublayer representation with a TemporalId equal to hrd_max_tid[i]. This includes the HRD parameters starting from the fixed_pic_rate_general_flag[i] syntax element to the sublayer_hrd_parameters(i) syntax structure, which follows the "if (general_vcl_hrd_params_present_flag)" condition of the ols_hrd_parameters syntax structure.

[0111] Additionally, for example, vps_num_ols_hrd_params_minus1+1 indicates the number of ols_hrd_parameters() syntax structures present in the VPS when the vps_general_hrd_params_present_flag value is equal to 1. The num_ols_hrd_params_minus1 value should be in the range of 0 to TotalNumOlss-1.

[0112] In addition, for example, the syntax element hrd_max_tid[i] may indicate the TemporalId of the highest sublayer representation having HRD parameters included in the i-th ols_hrd_parameters() syntax structure. The value of hrd_max_tid[i] may be in the range of 0 to vps_max_sublayers_minus1. When vps_max_sublayers_minus1 is equal to 0, the hrd_max_tid[i] value may be inferred to be equal to 0. When the syntax element hrd_max_tid[i] is not present, the hrd_max_tid[i] value may be inferred to be equal to vps_max_sublayers_minus1.

[0113] In addition, for example, the syntax element vps_ols_hrd_idx[i] may indicate the index of the ols_hrd_parameters() syntax structure applied to the i-th multi-layer OLS. The index may be an index of the ols_hrd_parameters() syntax structure list of the VPS. That is, the syntax element ols_hrd_idx[i] may indicate the index of the ols_hrd_parameters() syntax structure applied to the i-th multi-layer OLS among the multiple ols_hrd_parameters() syntax structures of the VPS. Herein, the ols_hrd_idx[i] value should be in the range of 0 to vps_num_ols_hrd_params_minus1.

[0114] If NumLayersInOls[i] is greater than 1, and if vps_ols_hrd_idx[i] does not exist, the following may be inferred. For example, if vps_num_ols_hrd_params_minus1 is equal to 0, then the vps_ols_hrd_idx[i] value may be inferred to be equal to 0, otherwise (i.e., when vps_num_ols_hrd_params_minus1 is greater than 0, and when vps_num_ols_hrd_params_minus1+1 is equal to NumMultiLayerOlss), the vps_ols_hrd_idx[i] value may be inferred to be equal to i.

[0115] Furthermore, in the case of a single-layer OLS (ie, when NumLayersInOls[i] is equal to 1), the ols_hrd_parameters() syntax structure applied to the i-th OLS may be present in the SPS referenced by the layers within the i-th OLS.

[0116] For i ranging from 1 to NumMultiLayerOlss-1, each ols_hrd_parameters() syntax structure of a VPS may be referenced by at least one vps_ols_hrd_idx[i] value.

[0117] DPB related information and / or HRD related information may be signaled as described above. In addition, the signaling method of vps_ols_dpb_pic_width[i], vps_ols_dpb_pic_height[i], vps_ols_dpb_chroma_format[i], vps_ols_dpb_bitdepth_minus8[i], vps_ols_dpb_params_idx[i], vps_ols_dpb_params_idx[i] according to conventional (or existing) video / image standards may have the following problems.

[0118] More specifically, the above syntax element may be signaled only for an OLS having multiple layers. However, when the above syntax element is referred to during the decoding process, the index of the target OLS index (i.e., the index of the decoded OLS) may refer to the entirety of the OLS list. That is, the index of the target OLS of the above syntax element may refer to all OLSs including an OLS having a single layer and an OLS having multiple layers.

[0119] In the case where the target OLS is an OLS having multiple layers, the above-mentioned mismatch (or inconsistency) of the target OLS index may cause the decoding device to indicate (or specify) an erroneous set of DPB information and HRD information. In other words, although the above-mentioned syntax element is signaled only for an OLS including multiple layers, since the target OLS index of the above-mentioned syntax element is configured to include the indexes of all OLSs of an OLS having a single layer, the decoding device may indicate erroneous DPB-related information and HRD-related information as OLS information, rather than DPB-related information and HRD-related information for the target OLS.

[0120] Accordingly, the present disclosure proposes a solution to the above troubles (or problems). The proposed embodiments can be applied independently or in combination.

[0121] As an example, a mapping may be defined between a list of all OLSs signaled in a VPS and a list of OLSs having a number of layers greater than 1. That is, for example, a mapping may be defined between a list of all OLSs signaled in a VPS and a list of OLSs having a number of layers greater than 1. An OLS having a number of layers greater than 1 may be referred to as a multi-layer OLS.

[0122] More specifically, for example, a) the mapping should be able to transform the index of the list of all OLSs into the same OLS index in the list of OLSs with multiple layers. In other words, the mapping should be able to transform the index of the target OLS in the list of all OLSs into the index of the target OLS in the list of OLSs with multiple layers.

[0123] For example, b) for a value i ranging from 0 to the number of OLSs minus 1, the array mapping the above two lists may be referred to as MultiLayeredOlsIdx[i]. The value of MultiLayeredOlsIdx[i] may indicate the correlation between the i-th OLS (i.e., all OLSs) and the j-th multilayer OLS having a value of j equal to MultiLayeredOlsIdx[i].

[0124] As an example, the above array MultiLayeredOlsIdx[i] may be used to obtain the corresponding values ​​of vps_ols_dpb_pic_width[j], vps_ols_dpb_pic_height[j], vps_ols_dpb_chroma_format[j], vps_ols_dpb_bitdepth_minus8[j], vps_ols_dpb_params_idx[j] and vps_ols_hrd_idx[j] for a given OLS index TargetOlsIdx.

[0125] For example, the steps described in detail below can be applied to the embodiments of the present disclosure. That is, the following steps can be used to provide an exemplary description of the embodiments.

[0126] For example, the coding device may derive information related to OLS. For example, the coding device may derive HRD parameters and / or DPB parameters. OLS related information may include HRD parameter related information (ie, OLS HRD information) and / or DPB parameter related information (ie, OLS DPB information). The coding device may encode a picture (or multiple pictures) based on OLS related information. The coding device may encode a picture (or multiple pictures) based on at least one of the HRD parameters and / or DPB parameters. Thereafter, the coding device may encode video / image information including OLS related information, and then may output a bitstream. For example, the coding device may encode video / image information including HRD parameter related information and / or DPB parameter related information. Herein, the bitstream may be a multi-layer bitstream. That is, the bitstream may include at least one sub-bitstream. The coding process of OLS related information (or HRD parameter related information and / or DPB parameter related information) may be performed based on the embodiments of the present disclosure.

[0127] In addition, for example, the decoding device can derive video / image information from the bitstream. The bitstream may include at least one sub-bitstream. The sub-bitstream may be associated with a layer or OLS. For example, the sub-bitstream extraction process may be a specified process, during which the NAL units of the bitstream that do not belong to the target set determined by the target OLS index and the target highest TemporalId are removed together with the output sub-bitstream consisting of the NAL units of the bitstream belonging to the target set. The video / image information may include OLS related information. In addition, for example, the OLS related information may include HRD parameter related information and / or DPB parameter related information. The decoding device may decode / output a picture (or multiple pictures) based on the OLS related information. For example, the decoding device may decode / output a picture (or multiple pictures) based on at least one of the HRD parameter related information and / or the DPB parameter related information. That is, for example, the decoding device may decode or output a picture (or multiple pictures) based on OLS / DPB / HRD.

[0128] The above embodiments may be implemented as follows: For example, the above embodiments may be expressed according to the VVC standard specification as follows.

[0129] [Table 4]

[0130]

[0131]

[0132] [Table 5]

[0133]

[0134]

[0135]

[0136]

[0137]

[0138]

[0139]

[0140]

[0141]

[0142]

[0143]

[0144]

[0145]

[0146]

[0147] Table 4 may indicate a process of deriving a multi-layer OLS index (MultiLayeredOlsIdx[i]) of the i-th OLS.

[0148] For example, referring to Table 4, when the i-th OLS includes a number of layers greater than 1 (i.e., when NumLayersInOls[i]>1), MultiLayeredOlsIdx[i] may be inferred to be equal to NumMultiLayerOlss, and then the NumMultiLayerOlss value may be incremented by 1. That is, the MultiLayeredOlsIdx[] of a later-order multilayer OLS after the i-th OLS may be inferred to be equal to a value that is 1 greater than the MultiLayeredOlsIdx[i] of the i-th OLS.

[0149] More specifically, for example, in the case where the target OLS is the nth OLS among the multi-layer OLSs, the multi-layer OLS index of the target OLS can be derived as n-1. For example, when the target OLS, which is the i-th OLS among all OLSs, is the n-th OLS among the multi-layer OLSs, the multi-layer OLS index of the target OLS (MultiLayeredOlsIdx[i]) can be derived as n-1.

[0150] In addition, for example, referring to Table 5, the DPB parameters and / or HRD parameters for the target OLS may be derived by using MultiLayeredOlsIdx[TargetOlsIdx] for the target OLS.

[0151] For example, referring to Table 5, when the number of layers of the target OLS is greater than 1 (when NumLayersInOls[TargetOlsIdx] is greater than 1), that is, when the target OLS is a multi-layer OLS, the variable PicWidthMaxInSamplesY can be configured to be the same as vps_ols_dpb_pic_width[MultiLayeredOlsIdx[TargetOlsIdx]], and the variable PicHeightMaxInSamplesY can be configured to be the same as vps_ols_dpb_pic_height [MultiLayeredOlsIdx[TargetOlsIdx]], the variable PicSizeMaxInSamplesY can be configured to be the same as PicWidthMaxInSamplesY*PicHeightMaxInSamplesY, and the dpb_parameters() syntax structure applicable to the target OLS can be identified as vps_ols_dpb_params_idx[MultiLayeredOlsIdx[TargetOlsIdx]] present in the VPS.

[0152] In addition, for example, referring to Table 5, when the number of layers of the target OLS is not equal to 1 (when NumLayersInOls[TargetOlsIdx] is not equal to 1), that is, when the target OLS is a multi-layer OLS, the general_hrd_parameters() syntax structure of the VPS and the vps_ols_hrd_idx[MultiLayeredOlsIdx[TargetOlsIdx]]th ols_hrd_parameters() syntax structure can be selected as the general_hrd_parameters() syntax structure and ols_hrd_parameters() syntax structure applicable to BitstreamToDecode.

[0153] In addition, for example, referring to Table 5, when the number of layers of the target OLS is greater than 1 (when NumLayersInOls[TargetOlsIdx] is greater than 1), that is, when the target OLS is a multi-layer OLS, the dpb_parameters() syntax structure applied to the target OLS can be identified as vps_ols_dpb_params_idx[MultiLayeredOlsIdx[TargetOlsIdx]] present in the VPS, and the variables PicWidthMaxInSamplesY, PicHeightMaxInSamplesY, MaxChromaFormat, and MaxBitDe Each of pthMinus8 may be configured to be the same as vps_ols_dpb_pic_width[MultiLayeredOlsIdx[TargetOlsIdx]], vps_ols_dpb_pic_height[MultiLayeredOlsIdx[TargetOlsIdx]], vps_ols_dpb_chroma_format[MultiLayeredOlsIdx[TargetOlsIdx]], and vps_ols_dpb_bitdepth_minus8[MultiLayeredOlsIdx[TargetOlsIdx]] of the VPS, respectively.

[0154] In addition, for example, referring to Table 5, when there are VCL HRD parameters or NAL HRD parameters, the ols_hrd_parameters() syntax structure in all SPS NAL units referenced by the i-th layer and all referenced VPS Each value of cpb_size_value_minus1[tIdTarget][j] of the j-th CPB in the vps_ols_hrd_idx[MultiLayeredOlsIdx[targetOlsIdx]]-th entry in the list of the ols_hrd_parameters() syntax structure within the NAL unit may be overwritten (or reconfigured) to correspond to SubpicCpbSizeVcl[SubpicSetLevelIdx][subpicIdx] and SubpicCpbSizeNal[SubpicSetLevelIdx][subpicIdx] derived by Equations D.5 and D.6, respectively, and SubpicBitrateVcl[SubpicSetLevelIdx][subpicIdx] and SubpicBitrateNal[SubpicSetLevelIdx][subpicIdx] derived by Equations D.7 and D.8, respectively. Herein, for a sub-picture having the same sub-picture index as subpicIdx, SubpicSetLevelIdx may be derived by equation D.10, j may be in the range of 0 to hrd_cpb_cnt_minus1, and i may be in the range of 0 to NumLayersInOls[targetOlsIdx] - 1. In addition, equations D.5, D.6, D.7, D.8, and D.10 may be the same as those disclosed in the VVC standard.

[0155] In addition, for example, referring to Table 5, when sli_cbr_constraint_flag is equal to 1, all NAL units with nal_unit_type equal to FD_NUT and padding payload SEI messages not associated with the VCL NAL unit of the sub-picture can be removed. And, the j-th CPB cbr_flag[tIdTarget][j] of the vps_ols_hrd_idx[MultiLayeredOlsIdx[targetOlsIdx]]-th entry in the list of the ols_hrd_parameters() syntax structure of all referenced VPS NAL units and SPS NAL units can be set (or configured) to be equal to 1. Herein, j can be in the range of 0 to hrd_cpb_cnt_minus1. And, otherwise, ie, when sli_cbr_constraint_flag is equal to 0, all NAL units with NAL_unit_type equal to FD_NUT and padding payload SEI messages may be removed and cbr_flag[tIdTarget][j] may be set to 0.

[0156] Figure 4 The image encoding method performed by the encoding device according to the present disclosure is briefly illustrated. Figure 4 The method disclosed in can be Figure 2 More specifically, for example, Figure 4 S400 to S420 in the above may be performed by the entropy encoder of the encoding device. Also, although not shown in the figure, the process of performing the DPB management process may be performed by the DPB of the encoding device, and the process for decoding the current picture may be performed by the predictor and residual processor of the encoding device.

[0157] The encoding device derives a multi-layer OLS index of a target OLS in a list of a multi-layer output layer set (OLS) (S400). The encoding device may derive a multi-layer OLS index of a target OLS in a list of a multi-layer output layer set (OLS). Herein, for example, the multi-layer OLS may be an OLS including a plurality of layers. In addition, for example, the target OLS may be one of the multi-layer OLSs.

[0158] For example, the encoding device may derive a multi-layer OLS index as shown in the above Table 4. For example, in the case where the target OLS is the nth OLS among the multi-layer OLSs, the multi-layer OLS index of the target OLS may be derived as n-1. For example, when the target OLS, which is the i-th OLS among all OLSs, is the nth OLS among the multi-layer OLSs, the multi-layer OLS index (MultiLayeredOlsIdx[i]) of the target OLS may be derived as n-1.

[0159] The encoding device generates hypothetical reference decoder (HRD) related information and decoded picture buffer (DPB) related information for the target OLS based on the multi-layer OLS index (S410). The encoding device can decode / encode the picture in the target OLS, and can derive HRD parameters and / or DPB parameters for the target OLS. In addition, the encoding device can generate and encode HRD related information about HRD parameters and / or DPB related information about DPB parameters. For example, the encoding device can derive DPB parameters and / or HRD parameters for DPB processing.

[0160] For example, HRD related information and / or DPB related information may include vps_ols_dpb_pic_width[MultiLayeredOlsIdx[TargetOlsIdx]], vps_ols_dpb_pic_height[MultiLayeredOlsIdx[TargetOlsIdx]], vps_ols_dpb_chroma_format[MultiLayeredOlsIdx[TargetOlsIdx]], vps_ols_dpb_bitdepth_minus8[MultiLayeredOlsIdx[TargetOlsIdx]], vps_ols_dpb_params_idx[MultiLayeredOlsIdx[TargetOlsIdx]], and / or vps_ols_hrd_idx[MultiLayeredOlsIdx[TargetOlsIdx]].

[0161] For example, the HRD related information may include an HRD index of an HRD parameter syntax structure for a target OLS. The HRD parameter syntax structure may be a syntax structure of an HRD parameter for a target OLS. The HRD index may be an HRD index of a multi-layer index. For example, the HRD index may indicate an HRD parameter syntax structure for a target OLS. The syntax element of the HRD index may be the above-mentioned vps_ols_hrd_idx[MultiLayeredOlsIdx[TargetOlsIdx]].

[0162] For example, the encoding device may generate an HRD parameter syntax structure of the target OLS, and generate an HRD index indicating the HRD parameter syntax structure of the target OLS.

[0163] In addition, for example, the DPB related information may include a syntax element for the width of a decoded picture buffer (DPB) of the target OLS, a syntax element for the height of the DPB, a syntax element for the chroma format of the DPB, a syntax element for the bit depth of the DPB, and / or a DPB index for a DPB parameter syntax structure of the target OLS. The DPB related information may be a syntax element for a multi-layer index. For example, the DPB index may indicate a DPB parameter syntax structure of the target OLS. The syntax element regarding the DPB width may be the above-mentioned vps_ols_dpb_pic_width[MultiLayeredOlsIdx[TargetOlsIdx]], the syntax element regarding the DPB height may be the above-mentioned vps_ols_dpb_pic_height[MultiLayeredOlsIdx[TargetOlsIdx]], the syntax element regarding the chroma format of the DPB may be the above-mentioned vps_ols_dpb_chroma_format[MultiLayeredOlsIdx[TargetOlsIdx]], the syntax element regarding the bit depth of the DPB may be the above-mentioned vps_ols_dpb_bitdepth_minus8[MultiLayeredOlsIdx[TargetOlsIdx]], and the syntax element of the DPB index may be the above-mentioned vps_ols_dpb_params_idx[MultiLayeredOlsIdx[TargetOlsIdx]].

[0164] For example, the encoding device may derive a DPB parameter of the target OLS and may generate DPB-related information for the DPB parameter.

[0165] In addition, for example, the encoding device may perform DPB management processing based on HRD parameters and / or DPB parameters. For example, the encoding device may perform picture management processing on the decoded picture of the DPB based on HRD parameters and / or DPB parameters. For example, the encoding device may add the decoded picture to the DPB, or the encoding device may remove the decoded picture in the DPB. For example, the decoded picture in the DPB may be used as a reference picture for inter-frame prediction of the picture in the target OLS, or the decoded picture in the DPB may be used as an output picture. The decoded picture may represent a picture that has been decoded before the current picture in the target OLS according to the decoding order.

[0166] The encoding device encodes the video information including the HRD related information and the DPB related information (S420). The encoding device may encode the HRD related information and / or the DPB related information. The video information may include the HRD related information and / or the DPB related information.

[0167] In addition, the encoding device can decode the picture of the target OLS. In addition, for example, the encoding device can update the DPB based on the HRD-related information and / or the DPB-related information for the target OLS. For example, the encoding device can perform DPB management processing on the decoded picture of the DPB based on the HRD-related information and / or the DPB-related information. For example, the encoding device can add the decoded picture to the DPB, or the encoding device can remove the decoded picture in the DPB. For example, the decoded picture in the DPB can be used as a reference picture for inter-frame prediction of the picture in the target OLS, or the decoded picture in the DPB can be used as an output picture. The decoded picture can represent a picture that has been decoded before the current picture according to the decoding order in the target OLS.

[0168] In addition, for example, the encoding device may decode the picture of the target OLS based on the DPB. For example, the encoding device may perform inter-frame prediction on the block within the picture based on the reference picture of the DPB to derive the prediction sample, and then the encoding device may generate the reconstructed sample and / or reconstructed picture of the picture based on the prediction sample. In addition, for example, the encoding device may derive the residual sample in the block within the picture, and may generate the reconstructed sample and / or reconstructed picture by adding the prediction sample and the residual sample.

[0169] In addition, for example, the encoding device may generate and encode prediction information for a block of a picture of a target OLS. In this case, various prediction methods disclosed in the present disclosure such as inter-frame prediction or intra-frame prediction may be applied. For example, the encoding device may determine whether to perform inter-frame prediction or intra-frame prediction on a block, and the encoding device may also determine a specific inter-frame prediction mode or a specific intra-frame prediction mode based on an RD cost. And, according to the determined mode, the encoding device may derive a prediction sample of the block. The prediction information may include prediction mode information for the block. The video information may include prediction information.

[0170] In addition, for example, the encoding apparatus may include residual information about a block of the current picture.

[0171] For example, the encoding device may derive residual samples by subtracting original samples corresponding to the block and predicted samples.

[0172] Thereafter, for example, the encoding device may quantize the residual samples to derive quantized residual samples. Then, the encoding device may derive transform coefficients based on the quantized residual samples, and may generate and encode residual information based on the transform coefficients. Alternatively, for example, the encoding device may quantize the residual samples to derive quantized residual samples, and then the encoding device may transform the quantized residual samples to derive transform coefficients. Thereafter, the encoding device may generate and encode residual information based on the transform coefficients. The video information may include residual information. Alternatively, for example, the encoding device may encode the video information and output the encoded video information in a bitstream format.

[0173] The encoding device can generate a reconstructed sample and / or a reconstructed picture by adding the predicted sample and the residual sample. Thereafter, as described above, a loop filtering process such as deblocking filtering, SAO and / or ALF process can be applied to the reconstructed sample as needed to improve the subjective / objective picture quality.

[0174] In addition, the bit stream including the video information can be sent to the decoding device via a network or a (digital) storage medium. Herein, the network may include a broadcast network and / or a communication network, etc., and the digital storage medium may include various storage media such as USB, SD, CD, DVD, Blu-ray, HDD, SSD, etc.

[0175] Figure 5 An encoding device that performs an image encoding method according to the present disclosure is briefly illustrated. Figure 4 The method disclosed in can be Figure 5 More specifically, for example, Figure 5 The entropy encoder of the encoding device can perform Figure 4 Also, although not shown in the figure, the process of performing the DPB management process may be performed by the DPB of the encoding device, and the process for decoding the current picture may be performed by the predictor and the residual processor of the encoding device.

[0176] Figure 6 The image decoding method performed by the decoding device according to the present disclosure is briefly illustrated. Figure 6 The method disclosed in can be Figure 3 More specifically, for example, Figure 6 S600 to S610 in the above may be performed by an entropy decoder of a decoding device, and Figure 6 S620 in may be performed by the DPB, the predictor, and the residual processor of the decoding device.

[0177] The decoding device derives a multi-layer OLS index of a target OLS in a list of a multi-layer output layer set (OLS) (S600). The decoding device may derive a multi-layer OLS index of a target OLS from a list of multi-layer OLSs. Herein, for example, the multi-layer OLS may be an OLS including a plurality of layers. And, for example, the target OLS may be one of the multi-layer OLSs.

[0178] For example, the decoding device may derive a multi-layer OLS index as shown in the above Table 4. For example, in the case where the target OLS is the nth OLS among the multi-layer OLSs, the multi-layer OLS index of the target OLS may be derived as n-1. For example, when the target OLS, which is the i-th OLS among all OLSs, is the nth OLS among the multi-layer OLSs, the multi-layer OLS index (MultiLayeredOlsIdx[i]) of the target OLS may be derived as n-1.

[0179] The decoding device obtains information related to a hypothetical reference decoder (HRD) and a decoded picture buffer (DPB) for a target OLS based on a multi-layer OLS index (S610). The decoding device may obtain information related to a hypothetical reference decoder (HRD) and information related to a decoded picture buffer (DPB) of a target OLS based on a multi-layer OLS index.

[0180] For example, the decoding device may obtain information related to HRD and / or information related to DPB for a multi-layer index. For example, the information related to HRD and / or the information related to DPB may include vps_ols_dpb_pic_width[MultiLayeredOlsIdx[TargetOlsIdx]], vps_ols_dpb_pic_height[MultiLayeredOlsIdx[TargetOlsIdx]], vps_ols_dpb_chroma_format[MultiLayeredOlsIdx[TargetOlsIdx]], vps_ols_dpb_bitdepth_minus8[MultiLayeredOlsIdx[TargetOlsIdx]], vps_ols_dpb_params_idx[MultiLayeredOlsIdx[TargetOlsIdx]], and / or vps_ols_hrd_idx[MultiLayeredOlsIdx[TargetOlsIdx]].

[0181] For example, the HRD related information may include an HRD index for an HRD parameter syntax structure for a target OLS. The HRD index may be an HRD index of a multi-layer index. For example, the HRD index may indicate an HRD parameter syntax structure for a target OLS. The syntax element of the HRD index may be the above-mentioned vps_ols_hrd_idx[MultiLayeredOlsIdx[TargetOlsIdx]].

[0182] In addition, for example, the DPB related information may include a syntax element for the width of a decoded picture buffer (DPB) of the target OLS, a syntax element for the height of the DPB, a syntax element for the chroma format of the DPB, a syntax element for the bit depth of the DPB, and / or a DPB index for a DPB parameter syntax structure of the target OLS. The DPB related information may be a syntax element for a multi-layer index. For example, the DPB index may indicate a DPB parameter syntax structure of the target OLS. The syntax element regarding the DPB width may be the above-mentioned vps_ols_dpb_pic_width[MultiLayeredOlsIdx[TargetOlsIdx]], the syntax element regarding the DPB height may be the above-mentioned vps_ols_dpb_pic_height[MultiLayeredOlsIdx[TargetOlsIdx]], the syntax element regarding the chroma format of the DPB may be the above-mentioned vps_ols_dpb_chroma_format[MultiLayeredOlsIdx[TargetOlsIdx]], the syntax element regarding the bit depth of the DPB may be the above-mentioned vps_ols_dpb_bitdepth_minus8[MultiLayeredOlsIdx[TargetOlsIdx]], and the syntax element of the DPB index may be the above-mentioned vps_ols_dpb_params_idx[MultiLayeredOlsIdx[TargetOlsIdx]].

[0183] The decoding apparatus decodes the picture in the target OLS based on the HRD-related information and the DPB-related information ( S620 ).

[0184] For example, the decoding device may derive HRD parameters for the target OLS based on HRD related information. For example, the decoding device may derive HRD parameters for the target OLS based on the HRD parameter syntax structure of the target OLS derived based on the HRD index. In addition, for example, the decoding device may derive DPB parameters for the target OLS based on DPB related information.

[0185] For example, the decoding device may perform DPM management processing on a decoded picture buffer (DPB) based on HRD parameters and / or DPB parameters for the target OLS. For example, the decoding device may perform picture management processing on the decoded picture of the DPB based on HRD parameters and / or DPB parameters. For example, the decoding device may add the decoded picture to the DPB, or the decoding device may remove the decoded picture in the DPB. For example, the decoded picture in the DPB may be used as a reference picture for inter-frame prediction of the picture in the target OLS, or the decoded picture in the DPB may be used as an output picture. The decoded picture may represent a picture that has been decoded before the current picture in the target OLS according to the decoding order.

[0186] For example, the decoding device may decode the picture within the target OLS based on the DPB in which the DPB management process has been performed. For example, the decoding device may perform inter-frame prediction on the block within the picture based on the reference picture of the DPB to derive the prediction sample, and then the decoding device may generate the reconstructed sample and / or reconstructed picture of the picture based on the prediction sample. In addition, for example, the decoding device may derive the residual sample in the block within the picture based on the residual information received through the bitstream, and may generate the reconstructed sample and / or reconstructed picture by adding the prediction sample and the residual sample.

[0187] Thereafter, loop filtering processes such as deblocking filtering, SAO and / or ALF processes may be applied to the reconstructed samples as needed in order to improve the subjective / objective picture quality.

[0188] Figure 7 A decoding device for performing an image decoding method according to the present disclosure is briefly illustrated. Figure 6 The method disclosed in can be Figure 7 More specifically, for example, Figure 7 The entropy decoder of the decoding device can perform Figure 6 S600 to S610 in, and Figure 7 The DPB, predictor and residual processor of the decoding device can perform Figure 6 The S620 in the.

[0189] As described above, according to the present disclosure, signaling of HRD-related information and DPB-related information can be efficiently performed by deriving the index of the list of multi-layer OLSs among all OLSs, and therefore, the overall coding efficiency can be enhanced.

[0190] In addition, according to the present disclosure, HRD-related information and DPB-related information signaled only for multi-layer OLSs can be prevented from being mapped to an erroneous (or incorrect) OLS by deriving an index of a list of multi-layer OLSs among all OLSs. And, therefore, the overall coding efficiency can be enhanced.

[0191] In the above embodiments, methods are described based on a flow chart with a series of steps or boxes. The present disclosure is not limited to the order of the above steps or boxes. Some steps or boxes can be performed in an order different from other steps or boxes mentioned above or performed simultaneously. In addition, it will be understood by those skilled in the art that the steps shown in the flow chart are not exclusive, and other steps may also be included, or one or more steps in the flow chart may be deleted without affecting the scope of the present disclosure.

[0192] The embodiments described in this specification may be implemented on a processor, a microprocessor, a controller or a chip. For example, the functional units shown in each figure may be implemented on a computer, a processor, a microprocessor, a controller or a chip. In this case, information (e.g., information about instructions) or algorithms for implementation may be stored in a digital storage medium.

[0193] In addition, the decoding device and encoding device of the present disclosure can be included in the following devices: multimedia broadcast sending / receiving devices, mobile communication terminals, home theater video devices, digital theater video devices, surveillance cameras, video chat devices, real-time communication devices such as video communication, mobile streaming devices, storage media, portable cameras, VoD service providing devices, over-the-top (OTT) video devices, Internet streaming service providing devices, three-dimensional (3D) video devices, teleconferencing video devices, transportation user devices (e.g., vehicle user devices, aircraft user devices, and ship user devices) and medical video devices; and the decoding device and encoding device of the present disclosure can be used to process video signals or data signals. For example, over-the-top (OTT) video devices may include game consoles, Blu-ray players, Internet access televisions, home theater systems, smart phones, tablet computers, digital video recorders (DVRs), etc.

[0194] In addition, the processing method of the present invention can be generated in the form of a program executed by a computer, and can be stored in a computer-readable recording medium. The multimedia data with a data structure according to the present invention can also be stored in a computer-readable recording medium. The computer-readable recording medium includes all types of storage devices in which computer-readable data is stored. The computer-readable recording medium may include, for example, BD, universal serial bus (USB), ROM, PROM, EPROM, EEPROM, RAM, CD-ROM, magnetic tape, floppy disk, and optical data storage device. In addition, the computer-readable recording medium includes a medium implemented in the form of a carrier wave (e.g., transmission via the Internet). In addition, the bit stream generated by the encoding method can be stored in a computer-readable recording medium or transmitted via a wired / wireless communication network.

[0195] In addition, the embodiments of the present disclosure may be implemented using a computer program product according to a program code, and the program code may be executed in a computer through the embodiments of the present disclosure. The program code may be stored on a computer readable carrier.

[0196] Figure 8 A structural diagram of a content streaming system to which the present disclosure is applied is illustrated.

[0197] A content streaming system to which the embodiments of the present disclosure are applied may mainly include an encoding server, a streaming server, a network server, a media storage, a user device, and a multimedia input device.

[0198] The encoding server compresses the content input from a multimedia input device such as a smartphone, a camera, or a camcorder into digital data to generate a bitstream and sends the bitstream to the streaming server. As another example, when a multimedia input device such as a smartphone, a camera, or a camcorder directly generates a bitstream, the encoding server can be omitted.

[0199] A bitstream may be generated by the encoding method or the bitstream generating method to which the embodiments of the present disclosure are applied, and a streaming server may temporarily store the bitstream in the process of transmitting or receiving the bitstream.

[0200] The streaming server sends multimedia data to the user device through the network server based on the user request, and the network server is used as a medium to notify the user of the service. When the user requests the required service from the network server, the network server delivers the request to the streaming server, and the streaming server sends the multimedia data to the user. In this case, the content streaming system may include a separate control server. In this case, the control server is used to control the command / response between the devices within the content streaming system.

[0201] The streaming server can receive content from a media storage and / or an encoding server. For example, when receiving content from an encoding server, the content can be received in real time. In this case, in order to provide a stable streaming service, the streaming server can store the bitstream for a predetermined period of time.

[0202] Examples of user devices may include mobile phones, smart phones, laptop computers, digital broadcast terminals, personal digital assistants (PDAs), portable multimedia players (PMPs), navigators, touch screen PCs, tablet PCs, ultrabooks, wearable devices (e.g., smart watches, smart glasses, and head mounted displays), digital TVs, desktop computers, and digital signage, etc. Each server within the content streaming system may operate as a distributed server, in which case data received from each server may be distributed.

[0203] The claims described in this disclosure can be combined in various ways. For example, the technical features of the method claims of this disclosure can be combined to implement as a device, and the technical features of the device claims of this disclosure can be combined to implement as a method. In addition, the technical features of the method claims of this disclosure and the technical features of the device claims can be combined to implement as a device, and the technical features of the method claims of this disclosure and the technical features of the device claims can be combined to implement as a method.

Claims

1. A device for decoding an image, the device comprising: Memory; as well as at least one processor, the at least one processor connected to the memory, the at least one processor configured to: Derives the multi-layer OLS index of the target OLS in the list of multi-layer output layer set OLS; Obtaining hypothesized reference decoder (HRD) related information and decoded picture buffer (DPB) related information for the target OLS based on the multi-layer OLS index; as well as Decoding the picture in the target OLS based on the HRD related information and the DPB related information, Wherein, the multi-layer OLS is an OLS comprising multiple layers, wherein the target OLS is one of the multi-layer OLSs, and Wherein, based on the OLS being a multi-layer OLS including a plurality of layers, the multi-layer OLS index is derived as a temporary value of a variable indicating the number of the multi-layer OLS, and the temporary value of the variable is incremented.

2. The device according to claim 1, wherein: The HRD related information includes an HRD index of an HRD parameter syntax structure for the target OLS.

3. The device according to claim 2, wherein: The at least one processor is configured to: Decoding the picture in the target OLS based on the HRD related information and the DPB related information; and The HRD parameter of the target OLS is derived based on the HRD parameter syntax structure of the target OLS derived based on the HRD index.

4. The device according to claim 1, wherein: The DPB related information includes syntax elements for the width of the decoding picture buffer DPB used for the target OLS, syntax elements for the height of the DPB, syntax elements for the chroma format of the DPB, syntax elements for the bit depth of the DPB, and a DPB index of the DPB parameter syntax structure for the target OLS.

5. The device according to claim 4, wherein: The at least one processor is configured to: A DPB parameter of the target OLS is derived based on the DPB related information.

6. A device for encoding an image, the device comprising: Memory; as well as at least one processor, the at least one processor connected to the memory, the at least one processor configured to: Derives the multi-layer OLS index of the target OLS in the list of multi-layer output layer set OLS; Generate hypothesized reference decoder (HRD) related information and decoded picture buffer (DPB) related information for the target OLS based on the multi-layer OLS index; as well as Encoding the video information including the HRD related information and the DPB related information, Wherein, the multi-layer OLS is an OLS comprising multiple layers, wherein the target OLS is one of the multi-layer OLSs, and Wherein, based on the OLS being a multi-layer OLS including a plurality of layers, the multi-layer OLS index is derived as a temporary value of a variable indicating the number of the multi-layer OLS, and the temporary value of the variable is incremented.

7. The device according to claim 6, wherein: The HRD related information includes an HRD index of an HRD parameter syntax structure for the target OLS.

8. The device according to claim 7, wherein: The at least one processor is configured to: generating the HRD parameter syntax structure of the target OLS; and The HRD index indicating the HRD parameter syntax structure of the target OLS is generated.

9. The device according to claim 6, wherein: The DPB related information includes syntax elements for the width of the decoding picture buffer DPB used for the target OLS, syntax elements for the height of the DPB, syntax elements for the chroma format of the DPB, syntax elements for the bit depth of the DPB, and a DPB index of the DPB parameter syntax structure for the target OLS.

10. The device according to claim 9, wherein: The at least one processor is configured to: deriving DPB parameters of the target OLS; and The DPB related information is generated for the DPB parameters.

11. A device for transmitting data for image information, the device comprising: at least one processor, the at least one processor being configured to obtain the image information including information related to a hypothetical reference decoder (HRD) and information related to a decoded picture buffer (DPB); as well as a transmitter configured to transmit the data including a bit stream for the image information, Among them, the multi-layer OLS index of the target OLS in the list of multi-layer output layer sets OLS is derived, wherein the HRD-related information and the DPB-related information for the target OLS based on the multi-layer OLS index are generated, and wherein the image information including the HRD related information and the DPB related information is encoded, Wherein, the multi-layer OLS is an OLS comprising multiple layers, wherein the target OLS is one of the multi-layer OLSs, and Wherein, based on the OLS being a multi-layer OLS including a plurality of layers, the multi-layer OLS index is derived as a temporary value of a variable indicating the number of the multi-layer OLS, and the temporary value of the variable is incremented.

Images