Video encoding method and video decoding method

Abstract

A video encoding method and a video decoding method are provided. A video decoding method according to the present invention comprises the steps of: obtaining, from a bitstream, information on the presence or absence of a virtual boundary for a current picture; decoding the information on the number of virtual boundaries based on the information on whether the virtual boundaries exist; decoding the information on the positions of the virtual boundaries based on the information on the number of virtual boundaries; and reconstructing the current picture based on the information on the position of the virtual boundary.

Description

[0001] This application is a divisional application of a patent application with application date of June 19, 2020, application number 202080039273.0, and title “Virtual Boundary Signaling Method for Video Encoding / Decoding”. Technical Field

[0002] The present invention relates to a video encoding / decoding method and apparatus and a recording medium storing a bit stream. More specifically, the present invention relates to a video encoding / decoding method and apparatus using virtual boundary signaling to reduce blurring caused by using a loop filter and to a recording medium for storing a bit stream generated by the video encoding method or apparatus of the present invention. Background Art

[0003] Recently, in various applications, the demand for high-resolution and high-quality images such as high-definition (HD) or ultra-high-definition (UHD) images has increased. As the resolution and quality of images increase, the amount of data increases accordingly. This is one of the reasons why transmission costs and storage costs increase when image data is transmitted through existing transmission media such as wired or wireless broadband channels or when image data is stored. In order to solve these problems of high-resolution and high-quality image data, efficient image encoding / decoding technology is required.

[0004] There are various video compression techniques, such as inter-frame prediction techniques that predict the values ​​of pixels in a current picture from the values ​​of pixels in a previous picture or a subsequent picture, intra-frame prediction techniques that predict the values ​​of pixels in an area of ​​the current picture from the values ​​of pixels in another area of ​​the current picture, transformation and quantization techniques for compressing the energy of residual signals, and entropy coding techniques that assign shorter codes to frequently occurring pixel values ​​and longer codes to less frequently occurring pixel values.

[0005] In conventional video encoding / decoding, video is predicted / reconstructed in units of blocks. Block artifacts are generated on the boundaries between reconstructed blocks. Therefore, a loop filter is used to reduce block artifacts and ringing distortion. However, when the boundaries are generated by dividing the video into different regions, the use of a loop filter may cause blurring between the boundaries, resulting in degradation of picture quality. Therefore, it is necessary to reduce the blurring phenomenon caused by the use of a loop filter. Summary of the invention

[0006] Technical issues An object of the present invention is to provide a video encoding / decoding method and apparatus with improved compression efficiency.

[0007] Another object of the present invention is to provide a video encoding / decoding method and apparatus for reducing blurring through a virtual boundary.

[0008] Another object of the present invention is to provide a method and apparatus for signaling evenly spaced virtual boundaries.

[0009] Another object of the present invention is to provide a method and apparatus for signaling a virtual boundary by using an offset.

[0010] Another object of the present invention is to provide a recording medium storing a bit stream generated by the video encoding / decoding method or apparatus of the present invention.

[0011] Technical Solution According to the present invention, a video decoding method may be provided. The video decoding method may include: obtaining information about whether filtering is performed on a virtual boundary from a bitstream; decoding information about the number of virtual boundaries based on the information about whether filtering is performed on the virtual boundary; decoding information about the position of the virtual boundary based on the information about the number of virtual boundaries; and reconstructing a current picture based on the information about the position of the virtual boundary.

[0012] The information on whether to perform filtering on the virtual boundary may be decoded based on the information on whether to use the virtual boundary.

[0013] Information on whether filtering is performed on a virtual boundary may be signaled in a sequence parameter set (SPS) and / or a picture header (PH).

[0014] The number of virtual boundaries may include the number of horizontal virtual boundaries and / or the number of vertical virtual boundaries.

[0015] The information about the position of the virtual boundary may include information about the position of the horizontal virtual boundary and / or information about the position of the vertical virtual boundary.

[0016] The step of reconstructing the current picture may include deriving a position of the virtual boundary for the current picture based on information about the position of the virtual boundary.

[0017] The position of the virtual boundary for the current screen may be obtained by applying a predetermined weight to the information about the position of the virtual boundary.

[0018] The position of the virtual boundary for the current picture may be derived by selectively using any one of information about the position of the virtual boundary signaled in the SPS and information about the position of the virtual boundary signaled in the PH.

[0019] When information about the position of the virtual boundary signaled in the SPS does not exist, the position of the virtual boundary for the current picture may be derived based on information about the position of the virtual boundary signaled in the PH.

[0020] In addition, according to the present invention, a video decoding method may be provided. The video decoding method may include: obtaining information about whether to perform filtering on a virtual boundary for a current picture from a bitstream; decoding information about a position of a virtual boundary based on the information about whether to perform filtering on the virtual boundary; and reconstructing the current picture based on the information about the position of the virtual boundary.

[0021] In addition, according to the present invention, a video encoding method may be provided. The video encoding method may include: deriving information about the position of a virtual boundary based on information about the number of virtual boundaries of a current picture; encoding the current picture based on the information about the position of the virtual boundary; and encoding the information about the number of virtual boundaries based on information about whether filtering is performed on the virtual boundary.

[0022] The information on whether to perform filtering on the virtual boundary may be encoded based on the information on whether to use the virtual boundary.

[0023] Information on whether filtering is performed on a virtual boundary may be signaled in a sequence parameter set (SPS) and / or a picture header (PH).

[0024] The number of virtual boundaries may include the number of horizontal virtual boundaries and / or the number of vertical virtual boundaries.

[0025] The information about the position of the virtual boundary may include information about the position of the horizontal virtual boundary and / or information about the position of the vertical virtual boundary.

[0026] The step of encoding the current picture may include deriving a position of the virtual boundary for the current picture based on the information about the position of the virtual boundary.

[0027] The position of the virtual boundary for the current screen may be obtained by applying a predetermined weight to the information about the position of the virtual boundary.

[0028] The position of the virtual boundary for the current picture may be derived by selectively using any one of information about the position of the virtual boundary signaled in the SPS and information about the position of the virtual boundary signaled in the PH.

[0029] When information about the position of the virtual boundary signaled in the SPS does not exist, the position of the virtual boundary for the current picture may be derived based on information about the position of the virtual boundary signaled in the PH.

[0030] In addition, the recording medium according to the present invention can store a bit stream generated by the video encoding method according to the present invention.

[0031] Beneficial Effects According to the present invention, a video encoding / decoding and apparatus with improved compression efficiency can be provided.

[0032] Furthermore, according to the present invention, an encoding / decoding method and apparatus for reducing a blurring phenomenon through a virtual boundary can be provided.

[0033] Furthermore, according to the present invention, a method and apparatus for signaling evenly spaced virtual boundaries may be provided.

[0034] Furthermore, according to the present invention, a method and apparatus for signaling a virtual boundary by using an offset may be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 is a block diagram showing a configuration of an encoding device according to an embodiment to which the present invention is applied.

[0036] Figure 2 is a block diagram showing a configuration of a decoding device according to an embodiment to which the present invention is applied.

[0037] Figure 3 is a diagram schematically showing a partition structure of an image when the image is encoded and decoded.

[0038] Figure 4 is a diagram illustrating an intra prediction process.

[0039] Figure 5 is a diagram illustrating an embodiment of an inter-picture prediction process.

[0040] Figure 6 is a diagram illustrating transform and quantization processing.

[0041] Figure 7 is a diagram showing reference samples that can be used for intra prediction.

[0042] Figure 8 is a diagram showing signaling of a conventional number of horizontal virtual borders and vertical virtual borders, an X position of a horizontal virtual border, and a Y position of a vertical virtual border.

[0043] Fig. 9 is a diagram illustrating a method of setting a virtual boundary through EdgeFlag in a transform block according to an embodiment of the present invention.

[0044] Fig.10 is a diagram illustrating setting a vertical virtual boundary according to an embodiment of the present invention.

[0045] Fig.11 is a diagram illustrating setting a horizontal virtual boundary according to an embodiment of the present invention.

[0046] Fig.12 is a diagram showing a method of representing a brightness sample in a picture according to an embodiment of the present invention. Fig.10 and Fig.11 Illustration of the vertical virtual boundary and the horizontal virtual boundary described in .

[0047] Fig.13 is a diagram illustrating a method of signaling evenly spaced virtual boundaries according to an embodiment of the present invention.

[0048] Fig.14 is a diagram illustrating a method of signaling a virtual boundary through an offset according to an embodiment of the present invention.

[0049] Fig.15 is a diagram illustrating a method of signaling a virtual boundary through an absolute value offset according to an embodiment of the present invention.

[0050] Fig.16 is a diagram illustrating a method of signaling evenly spaced virtual boundaries through offsets according to an embodiment of the present invention.

[0051] Fig.17 is a diagram illustrating a method (syntax) of signaling a virtual boundary through an offset value according to an embodiment of the present invention.

[0052] Fig.18 is a diagram illustrating a method (syntax) of signaling a virtual boundary through evenly spaced values / offset values ​​according to an embodiment of the present invention. DETAILED DESCRIPTION

[0053] Various modifications may be made to the present invention, and there are various embodiments of the present invention, wherein examples of various embodiments of the present invention will now be provided with reference to the accompanying drawings and described in detail. However, the present invention is not limited thereto, although the exemplary embodiments may be interpreted as including all modifications, equivalents or substitutions within the technical concept and technical scope of the present invention. In various aspects, similar figure numerals refer to the same or similar functions. In the accompanying drawings, the shapes and sizes of the elements may be exaggerated for clarity. In the following detailed description of the present invention, reference is made to the accompanying drawings that illustrate specific embodiments of the present invention in a graphical manner. These embodiments are described in sufficient detail to enable those skilled in the art to implement the present disclosure. It should be understood that the various embodiments of the present disclosure, although different, are not necessarily mutually exclusive. For example, without departing from the spirit and scope of the present disclosure, the specific features, structures and characteristics described herein in conjunction with one embodiment may be implemented in other embodiments. In addition, it should be understood that the position or arrangement of each element within each disclosed embodiment may be modified without departing from the spirit and scope of the present disclosure. Therefore, the following detailed description should not be regarded as having a limiting meaning, and the scope of the present disclosure is limited only by the appended claims (when properly interpreted, together with the full range of equivalents claimed by the claims).

[0054] The terms "first", "second", etc. used in the specification may be used to describe various components, but the components should not be interpreted as being limited to these terms. These terms are only used to distinguish one component from other components. For example, without departing from the scope of the present invention, a "first" component may be named a "second" component, and a "second" component may also be similarly named a "first" component. The term "and / or" includes a combination of multiple items or any one of the multiple items.

[0055] It will be understood that in this specification, when an element is simply referred to as being “connected to” or “coupled to” another element rather than being “directly connected to” or “directly coupled to” another element, the element may be “directly connected to” or “directly coupled to” another element, or connected to or coupled to another element with other elements interposed therebetween. Conversely, it will be understood that when an element is referred to as being “directly coupled to” or “directly connected to” another element, there are no intervening elements.

[0056] In addition, the components shown in the embodiments of the present invention are shown independently to represent the characteristic functions that are different from each other. Therefore, this does not mean that each component is composed of a separate hardware or software component unit. In other words, for convenience, each component includes each component in the listed components. Therefore, at least two components of each component can be combined to form a component, or a component can be divided into multiple components to perform each function. If it does not depart from the essence of the present invention, the embodiment in which each component is combined and the embodiment in which a component is divided are also included in the scope of the present invention.

[0057] The terms used in this specification are only used to describe specific embodiments and are not intended to limit the present invention. Unless there is a significantly different meaning in the context, the expression used in the singular includes the expression in the plural form. In this specification, it will be understood that terms such as "including", "having" etc. are intended to indicate the presence of features, numbers, steps, actions, elements, parts or combinations thereof disclosed in the specification, and are not intended to exclude the possibility that one or more other features, numbers, steps, actions, elements, parts or combinations thereof may exist or may be added. In other words, when a particular element is referred to as "included", it does not exclude elements other than the corresponding element, but may include other elements in an embodiment of the present invention or in the scope of the present invention.

[0058] In addition, some components may not be essential components for performing the basic functions of the present invention, but are selective components that only improve its performance. The present invention can be implemented by only including essential components for implementing the essence of the present invention without including components for improving performance. Structures that only include essential components without including selective components that only improve performance are also included in the scope of the present invention.

[0059] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. When describing the exemplary embodiments of the present invention, well-known functions or configurations will not be described in detail because they may unnecessarily obscure the understanding of the present invention. The same constituent elements in the accompanying drawings are represented by the same reference numerals, and repeated descriptions of the same elements will be omitted.

[0060] Hereinafter, an image may refer to a picture constituting a video, or may refer to the video itself. For example, "encoding or decoding an image or both encoding and decoding" may refer to "encoding or decoding a moving picture or both encoding and decoding", and may refer to "encoding or decoding one of the images of the moving picture or both encoding and decoding".

[0061] Hereinafter, the terms "motion picture" and "video" may be used as the same meaning and may be replaced with each other.

[0062] Hereinafter, a target image may be an encoding target image as an encoding target and / or a decoding target image as a decoding target. In addition, a target image may be an input image input to an encoding device, and an input image input to a decoding device. Here, the target image may have the same meaning as the current image.

[0063] Hereinafter, the terms "image", "picture", "frame" and "screen" may be used as the same meaning and may be replaced with each other.

[0064] Hereinafter, the target block may be an encoding target block as an encoding target and / or a decoding target block as a decoding target. In addition, the target block may be a current block as a target of current encoding and / or decoding. For example, the terms "target block" and "current block" may be used as the same meaning and may be replaced with each other.

[0065] Hereinafter, the terms "block" and "unit" may be used as the same meaning and may be replaced with each other. Alternatively, a "block" may refer to a specific unit.

[0066] In the following, the terms "region" and "segment" are used interchangeably.

[0067] Hereinafter, a specific signal may be a signal representing a specific block. For example, an original signal may be a signal representing a target block. A prediction signal may be a signal representing a prediction block. A residual signal may be a signal representing a residual block.

[0068] In an embodiment, each of the specific information, data, flags, indexes, elements, attributes, etc. may have a value. The value of the information, data, flags, indexes, elements, and attributes equal to "0" may represent a logical false or a first predefined value. In other words, the value "0", false, logical false, and the first predefined value may be replaced with each other. The value of the information, data, flags, indexes, elements, and attributes equal to "1" may represent a logical true or a second predefined value. In other words, the value "1", true, logical true, and the second predefined value may be replaced with each other.

[0069] When the variable i or j is used to represent a column, row, or index, the value of i can be an integer equal to or greater than 0, or an integer equal to or greater than 1. That is, the column, row, index, etc. can be counted from 0 or 1.

[0070] Description of terms Encoder: This refers to a device that performs encoding. In other words, it refers to an encoding device.

[0071] Decoder: Refers to a device that performs decoding. In other words, it refers to a decoding device.

[0072] Block: is an M×N sample array. Here, M and N may represent positive integers, and a block may represent a sample array in a two-dimensional form. A block may refer to a unit. A current block may represent an encoding target block that becomes a target at the time of encoding, or a decoding target block that becomes a target at the time of decoding. In addition, the current block may be at least one of a coding block, a prediction block, a residual block, and a transform block.

[0073] Sample: It is the basic unit of a block. d ), the sample points can be represented as In the present invention, a sample point may be used as the meaning of a pixel. That is, a sample point, a pel, and a pixel may have the same meaning as each other.

[0074] Unit: may refer to a coding and decoding unit. When encoding and decoding an image, a unit may be a region generated by partitioning a single image. In addition, when a single image is partitioned into sub-division units during encoding or decoding, a unit may represent a sub-division unit. That is, an image may be partitioned into a plurality of units. When encoding and decoding an image, a predetermined process for each unit may be performed. A single unit may be partitioned into sub-units having a size smaller than that of the unit. According to the function, a unit may represent a block, a macroblock, a coding tree unit, a coding tree block, a coding unit, a coding block, a prediction unit, a prediction block, a residual unit, a residual block, a transform unit, a transform block, and the like. In addition, in order to distinguish a unit from a block, a unit may include a luminance component block, a chrominance component block associated with the luminance component block, and a syntax element for each color component block. A unit may have various sizes and shapes, and specifically, the shape of a unit may be a two-dimensional geometric figure such as a square, a rectangle, a trapezoid, a triangle, a pentagon, and the like. Also, the unit information may include at least one of a unit type indicating a coding unit, a prediction unit, a transformation unit, etc., and a unit size, a unit depth, an order of encoding and decoding of the unit, and the like.

[0075] Coding tree unit: A single coding tree block configured with a luminance component Y and two coding tree blocks associated with chrominance components Cb and Cr. In addition, the coding tree unit may represent a syntax element including a block and each block. Each coding tree unit may be partitioned by using at least one of a quadtree partitioning method, a binary tree partitioning method, and a ternary tree partitioning method to configure subordinate units such as coding units, prediction units, transform units, etc. The coding tree unit may be used as a term for specifying a sample block that becomes a processing unit when encoding / decoding an image as an input image. Here, the quadtree may represent a quadtree.

[0076] When the size of the coding block is within a predetermined range, it is possible to divide it using only quadtree partitioning. Here, the predetermined range may be defined as at least one of the maximum size and the minimum size of the coding block that can be divided using only quadtree partitioning. Information indicating the maximum / minimum size of the coding block that allows quadtree partitioning may be signaled through a bitstream, and the information may be signaled in at least one unit of a sequence, a picture parameter, a parallel block group, or a slice (fragment). Optionally, the maximum / minimum size of the coding block may be a fixed size predetermined in the encoder / decoder. For example, when the size of the coding block corresponds to 256×256 to 64×64, it is possible to divide it using only quadtree partitioning. Optionally, when the size of the coding block is larger than the size of the maximum conversion block, it is possible to divide it using only quadtree partitioning. Here, the block to be divided may be at least one of a coding block and a transform block. In this case, the information indicating the division of the coding block (e.g., split_flag) may be a flag indicating whether quadtree partitioning is performed. When the size of the coding block falls within a predetermined range, it is possible to divide it using only binary or ternary tree partitioning. In this case, the above description of the quadtree partition can be applied to the binary tree partition or the ternary tree partition in the same manner.

[0077] Coding tree block: may be used as a term used to designate any one of a Y coding tree block, a Cb coding tree block, and a Cr coding tree block.

[0078] Neighboring block: may refer to a block adjacent to the current block. The block adjacent to the current block may refer to a block that touches the boundary of the current block or a block that is located within a predetermined distance from the current block. The neighboring block may refer to a block adjacent to a vertex of the current block. Here, the block adjacent to a vertex of the current block may refer to a block that is vertically adjacent to a neighboring block that is horizontally adjacent to the current block or a block that is horizontally adjacent to a neighboring block that is vertically adjacent to the current block.

[0079] Reconstructed neighboring block: may represent a neighboring block that is adjacent to the current block and has been encoded or decoded in space / time. Here, the reconstructed neighboring block may represent a reconstructed neighboring unit. The reconstructed spatial neighboring block may be a block that is within the current picture and has been reconstructed by encoding or decoding or both encoding and decoding. The reconstructed temporal neighboring block is a block at a position corresponding to the current block of the current picture within the reference image or a neighboring block of the block.

[0080] Unit depth: may represent the degree of partitioning of a unit. In a tree structure, the highest node (root node) may correspond to the first unit that is not partitioned. In addition, the highest node may have a minimum depth value. In this case, the depth of the highest node may be level 0. A node with a depth of level 1 may represent a unit generated by partitioning the first unit once. A node with a depth of level 2 may represent a unit generated by partitioning the first unit twice. A node with a depth of level n may represent a unit generated by partitioning the first unit n times. A leaf node may be the lowest node and a node that cannot be further partitioned. The depth of a leaf node may be the maximum level. For example, the predefined value of the maximum level may be 3. The depth of the root node may be the lowest, and the depth of the leaf node may be the deepest. In addition, when a unit is represented as a tree structure, the level at which the unit exists may represent the unit depth.

[0081] Bitstream: can represent a stream of bits including coded image information.

[0082] Parameter set: corresponds to header information among the configurations in the bitstream. At least one of a video parameter set, a sequence parameter set, a picture parameter set, and an adaptation parameter set may be included in the parameter set. In addition, the parameter set may include a slice header, a tile group header, and tile header information. The term "tile group" means a group of tiles and has the same meaning as a slice.

[0083] The adaptation parameter set may represent a parameter set that can be shared by being referenced in different pictures, sub-pictures, slices, tile groups, tiles, or bricks. In addition, information in the adaptation parameter set may be used by referring to different adaptation parameter sets for sub-pictures, slices, tile groups, tiles, or bricks within a picture.

[0084] Furthermore, regarding adaptation parameter sets, different adaptation parameter sets may be referenced by using identifiers of different adaptation parameter sets for a sub-picture, a slice, a tile group, a tile, or a partition within a picture.

[0085] Furthermore, regarding adaptation parameter sets, different adaptation parameter sets may be referenced by using identifiers of different adaptation parameter sets for slices, tile groups, tiles, or partitions within a sub-picture.

[0086] Furthermore, regarding adaptation parameter sets, different adaptation parameter sets may be referenced by using identifiers of different adaptation parameter sets for tiles or partitions within a slice.

[0087] Furthermore, with respect to adaptation parameter sets, different adaptation parameter sets may be referenced by using identifiers of different adaptation parameter sets for partitions within a tile.

[0088] Information about the adaptation parameter set identifier may be included in a parameter set or a header of a sub-picture, and an adaptation parameter set corresponding to the adaptation parameter set identifier may be used for the sub-picture.

[0089] Information about the adaptation parameter set identifier may be included in a parameter set or a header of a tile, and an adaptation parameter set corresponding to the adaptation parameter set identifier may be used for the tile.

[0090] Information about the adaptation parameter set identifier may be included in a header of the tile, and an adaptation parameter set corresponding to the adaptation parameter set identifier may be used for the tile.

[0091] A picture may be partitioned into one or more tile rows and one or more tile columns.

[0092] A sub-picture may be partitioned into one or more parallel block rows and one or more parallel block columns within a picture. A sub-picture may be an area having a rectangular / square form within a picture and may include one or more CTUs. In addition, at least one or more parallel blocks / blocks / strips may be included in a sub-picture.

[0093] A tile may be an area having a rectangular / square form within a picture and may include one or more CTUs. In addition, a tile may be partitioned into one or more partitions.

[0094] A partition may represent one or more CTU rows within a tile. A tile may be partitioned into one or more partitions, and each partition may have at least one or more CTU rows. A tile that is not partitioned into two or more may represent a partition.

[0095] A slice may include one or more tiles within a picture, and may include one or more partitions within a tile.

[0096] Parsing: may mean determining the value of a syntax element by performing entropy decoding, or may mean the entropy decoding itself.

[0097] Symbol: At least one of a syntax element, a coding parameter, and a transform coefficient value that can represent a coding / decoding target unit. In addition, the symbol can represent an entropy coding target or an entropy decoding result.

[0098] Prediction mode: may be information indicating a mode for encoding / decoding using intra prediction or a mode for encoding / decoding using inter prediction.

[0099] Prediction unit: may represent a basic unit when performing predictions such as inter prediction, intra prediction, inter compensation, intra compensation, and motion compensation. A single prediction unit may be partitioned into multiple partitions of smaller sizes, or may be partitioned into multiple lower-level prediction units. Multiple partitions may be basic units when performing prediction or compensation. Partitions generated by splitting a prediction unit may also be prediction units.

[0100] Prediction unit partition: may represent a shape obtained by partitioning a prediction unit.

[0101] A reference picture list may refer to a list including one or more reference pictures used for inter prediction or motion compensation. There are several types of available reference picture lists, including LC (List Combination), L0 (List 0), L1 (List 1), L2 (List 2), L3 (List 3).

[0102] The inter prediction indicator may refer to the direction of inter prediction of the current block (unidirectional prediction, bidirectional prediction, etc.). Optionally, the inter prediction indicator may refer to the number of reference pictures used to generate the prediction block of the current block. Optionally, the inter prediction indicator may refer to the number of prediction blocks used when performing inter prediction or motion compensation on the current block.

[0103] The prediction list utilization flag indicates whether at least one reference picture in a specific reference picture list is used to generate a prediction block. The prediction list utilization flag may be used to derive the inter prediction indicator, and conversely, the inter prediction indicator may be used to derive the prediction list utilization flag. For example, when the prediction list utilization flag has a first value of zero (0), it indicates that the reference picture in the reference picture list is not used to generate the prediction block. On the other hand, when the prediction list utilization flag has a second value of one (1), it indicates that the reference picture list is used to generate the prediction block.

[0104] The reference picture index may refer to an index indicating a specific reference picture in a reference picture list.

[0105] A reference picture may refer to a reference picture referenced by a specific block for the purpose of inter-frame prediction or motion compensation of the specific block. Alternatively, a reference picture may be a picture including a reference block referenced by a current block for inter-frame prediction or motion compensation. Hereinafter, the terms "reference picture" and "reference image" have the same meaning and are interchangeable.

[0106] A motion vector may be a two-dimensional vector used for inter-frame prediction or motion compensation. A motion vector may represent an offset between an encoding / decoding target block and a reference block. For example, (mvX, mvY) may represent a motion vector. Here, mvX may represent a horizontal component, and mvY may represent a vertical component.

[0107] The search range may be a two-dimensional area that is searched during inter prediction to retrieve a motion vector. For example, the size of the search range may be M×N. Here, M and N are both integers.

[0108] The motion vector candidate may refer to a prediction candidate block or a motion vector of the prediction candidate block when predicting a motion vector. In addition, the motion vector candidate may be included in a motion vector candidate list.

[0109] The motion vector candidate list may mean a list consisting of one or more motion vector candidates.

[0110] The motion vector candidate index may represent an indicator indicating a motion vector candidate in the motion vector candidate list. Alternatively, it may be an index of a motion vector predictor.

[0111] The motion information may represent information including at least one of items including a motion vector, a reference picture index, an inter prediction indicator, a prediction list utilization flag, a reference picture list information, a reference picture, a motion vector candidate, a motion vector candidate index, a merge candidate, and a merge index.

[0112] The merge candidate list may mean a list consisting of one or more merge candidates.

[0113] The merge candidate may represent a spatial merge candidate, a temporal merge candidate, a combined merge candidate, a combined bi-prediction merge candidate, or a zero merge candidate. The merge candidate may include motion information such as an inter prediction indicator, a reference picture index for each list, a motion vector, a prediction list utilization flag, and an inter prediction indicator.

[0114] The merge index may represent an indicator indicating a merge candidate in the merge candidate list. Alternatively, the merge index may indicate a block in a reconstructed block that is spatially / temporally adjacent to the current block, from which the merge candidate has been derived. Alternatively, the merge index may indicate at least one piece of motion information of the merge candidate.

[0115] Transform unit: may represent a basic unit when encoding / decoding (such as transform, inverse transform, quantization, inverse quantization, transform coefficient encoding / decoding) is performed on a residual signal. A single transform unit may be partitioned into a plurality of lower-level transform units having a smaller size. Here, the transform / inverse transform may include at least one of a first transform / first inverse transform and a second transform / second inverse transform.

[0116] Scaling: may refer to the process of multiplying the level of quantization by a factor. Transform coefficients may be generated by scaling the level of quantization. Scaling may also be referred to as inverse quantization.

[0117] Quantization parameter: may indicate a value used when a transform coefficient is used to generate a quantized level during quantization. The quantization parameter may also indicate a value used when a transform coefficient is generated by scaling the quantized level during inverse quantization. The quantization parameter may be a value mapped to a quantization step size.

[0118] Delta quantization parameter: may represent the difference between the predicted quantization parameter and the quantization parameter of the encoding / decoding target unit.

[0119] Scan: may refer to a method of ordering coefficients within a cell, block, or matrix. For example, changing a two-dimensional matrix of coefficients to a one-dimensional matrix may be called scanning, and changing a one-dimensional matrix of coefficients to a two-dimensional matrix may be called scanning or inverse scanning.

[0120] Transform coefficient: may refer to a coefficient value generated after performing a transform in an encoder. Transform coefficient may refer to a coefficient value generated after performing at least one of entropy decoding and inverse quantization in a decoder. A quantization level obtained by quantizing a transform coefficient or a residual signal or a quantized transform coefficient level may also fall within the meaning of a transform coefficient.

[0121] Quantization level: may represent a value generated by quantizing a transform coefficient or a residual signal in an encoder. Alternatively, the quantization level may represent a value that is a dequantization target subjected to dequantization in a decoder. Similarly, the quantized transform coefficient level as a result of transformation and quantization may also fall within the meaning of the quantization level.

[0122] Non-zero transform coefficient: may refer to a transform coefficient having a value other than zero, or a transform coefficient level or quantization level having a value other than zero.

[0123] Quantization matrix: may refer to a matrix used in a quantization process or an inverse quantization process performed to improve subjective image quality or objective image quality. The quantization matrix may also be referred to as a scaling list.

[0124] Quantization matrix coefficients: can represent each element in the quantization matrix. Quantization matrix coefficients can also be called matrix coefficients.

[0125] Default matrix: may represent a predetermined quantization matrix predefined in an encoder or a decoder.

[0126] Non-default matrix: may denote a quantization matrix that is not predefined in the encoder or decoder but is signaled by the user.

[0127] Statistical value: The statistical value for at least one of a variable, a coding parameter, a constant value, etc. having a calculable specific value can be one or more of the average value, summed value, weighted average value, weighted sum value, minimum value, maximum value, most frequently occurring value, median value, and interpolation value of the corresponding specific value.

[0128] Figure 1 is a block diagram showing a configuration of an encoding device according to an embodiment to which the present invention is applied.

[0129] The encoding device 100 may be an encoder, a video encoding device, or an image encoding device. A video may include at least one image. The encoding device 100 may sequentially encode at least one image.

[0130] Reference Figure 1 , the encoding device 100 may include a motion prediction unit 111, a motion compensation unit 112, an intra-frame prediction unit 120, a switch 115, a subtractor 125, a transform unit 130, a quantization unit 140, an entropy encoding unit 150, an inverse quantization unit 160, an inverse transform unit 170, an adder 175, a filter unit 180 and a reference picture buffer 190.

[0131] The encoding device 100 may perform encoding of an input image by using an intra mode or an inter mode or both an intra mode and an inter mode. In addition, the encoding device 100 may generate a bit stream including encoding information by encoding the input image, and output the generated bit stream. The generated bit stream may be stored in a computer-readable recording medium, or may be streamed through a wired / wireless transmission medium. When the intra mode is used as a prediction mode, the switch 115 may switch to the intra mode. Alternatively, when the inter mode is used as a prediction mode, the switch 115 may switch to the inter mode. Here, the intra mode may represent an intra prediction mode, and the inter mode may represent an inter prediction mode. The encoding device 100 may generate a prediction block for an input block of the input image. In addition, the encoding device 100 may encode the residual block using the residual of the input block and the prediction block after generating the prediction block. The input image may be referred to as a current image as a current encoding target. The input block may be referred to as a current block as a current encoding target, or may be referred to as an encoding target block.

[0132] When the prediction mode is the intra mode, the intra prediction unit 120 may use samples of a block that has been encoded / decoded and is adjacent to the current block as reference samples. The intra prediction unit 120 may perform spatial prediction on the current block by using the reference samples, or may generate prediction samples of the input block by performing spatial prediction. Here, intra prediction may refer to prediction within a frame.

[0133] When the prediction mode is the inter mode, the motion prediction unit 111 may retrieve the area that best matches the input block from the reference image when performing motion prediction, and derive a motion vector by using the retrieved area. In this case, the search area may be used as the area. The reference image may be stored in the reference picture buffer 190. Here, when encoding / decoding the reference image is performed, the reference image may be stored in the reference picture buffer 190.

[0134] The motion compensation unit 112 may generate a predicted block by performing motion compensation on the current block using a motion vector. Here, inter prediction may refer to prediction or motion compensation between frames.

[0135] When the value of the motion vector is not an integer, the motion prediction unit 111 and the motion compensation unit 112 may generate a prediction block by applying an interpolation filter to a partial area of ​​a reference picture. In order to perform inter-picture prediction or motion compensation on a coding unit, it may be determined which mode among the skip mode, merge mode, advanced motion vector prediction (AMVP) mode, and current picture reference mode is used for motion prediction and motion compensation of a prediction unit included in the corresponding coding unit. Then, inter-picture prediction or motion compensation may be performed differently according to the determined mode.

[0136] The subtractor 125 may generate a residual block by using the difference between the input block and the prediction block. The residual block may be referred to as a residual signal. The residual signal may represent the difference between the original signal and the prediction signal. In addition, the residual signal may be a signal generated by transforming or quantizing the difference between the original signal and the prediction signal, or by transforming and quantizing the difference between the original signal and the prediction signal. The residual block may be a residual signal of a block unit.

[0137] The transform unit 130 may generate a transform coefficient by performing a transform on the residual block and output the generated transform coefficient. Here, the transform coefficient may be a coefficient value generated by performing a transform on the residual block. When the transform skip mode is applied, the transform unit 130 may skip the transform on the residual block.

[0138] The quantized level may be generated by applying quantization to a transform coefficient or to a residual signal. Hereinafter, the quantized level may also be referred to as a transform coefficient in an embodiment.

[0139] The quantization unit 140 may generate a quantization level by quantizing the transform coefficient or the residual signal according to the parameter and output the generated quantization level. Here, the quantization unit 140 may quantize the transform coefficient by using a quantization matrix.

[0140] The entropy encoding unit 150 may generate a bitstream by performing entropy encoding on the value calculated by the quantization unit 140 or the encoding parameter value calculated when encoding is performed according to the probability distribution, and output the generated bitstream. The entropy encoding unit 150 may perform entropy encoding on sample information of the image and information for decoding the image. For example, the information for decoding the image may include a syntax element.

[0141] When entropy coding is applied, symbols are represented so that a smaller number of bits are allocated to symbols with a high probability of generation, and a larger number of bits are allocated to symbols with a low probability of generation, and thus, the size of the bitstream for the symbol to be encoded can be reduced. The entropy coding unit 150 may use a coding method for entropy coding such as exponential Golomb, context adaptive variable length coding (CAVLC), context adaptive binary arithmetic coding (CABAC), etc. For example, the entropy coding unit 150 may perform entropy coding by using a variable length coding / code (VLC) table. In addition, the entropy coding unit 150 may derive a binarization method of a target symbol and a probability model of a target symbol / binary bit, and perform arithmetic coding by using the derived binarization method and context model.

[0142] In order to encode a transform coefficient level (quantized level), the entropy encoding unit 150 may change a coefficient in a two-dimensional block form into a one-dimensional vector form by using a transform coefficient scanning method.

[0143] The coding parameters may include information such as syntax elements (flags, indexes, etc.) that are encoded in the encoder and sent to the decoder by signaling, as well as information derived when performing encoding or decoding. The coding parameters may represent information required when encoding or decoding an image. For example, at least one value or combination of the following items may be included in the coding parameters: unit / block size, unit / block depth, unit / block partition information, unit / block shape, unit / block partition structure, whether to perform quadtree partitioning, whether to perform binary tree partitioning, binary tree partition direction (horizontal or vertical), binary tree partition form (symmetric partitioning or asymmetric partitioning), whether the current coding unit is partitioned by ternary tree partitioning, the direction of ternary tree partitioning (horizontal or vertical), the type of ternary tree partitioning (symmetric type or asymmetric type), whether the current coding unit is partitioned by multi-type tree partitioning, and the type of multi-type tree partitioning. direction (horizontal or vertical), type of multi-type tree partition (symmetric or asymmetric), tree (binary tree or ternary tree) structure of multi-type tree partition, prediction mode (intra-frame prediction or inter-frame prediction), luminance intra-frame prediction mode / direction, chrominance intra-frame prediction mode / direction, intra-frame partition information, inter-frame partition information, coding block partition flag, prediction block partition flag, transform block partition flag, reference sample filtering method, reference sample filter taps, reference sample filter coefficients, prediction block filtering method, prediction block filter taps, prediction block filter coefficients, prediction block boundary filtering method, prediction block boundary filter taps, prediction block boundary filter coefficients, intra-frame prediction mode , inter prediction mode, motion information, motion vector, motion vector difference, reference picture index, inter prediction angle, inter prediction indicator, prediction list utilization flag, reference picture list, reference picture, motion vector predictor index, motion vector predictor candidate, motion vector candidate list, whether to use merge mode, merge index, merge candidate, merge candidate list, whether to use skip mode, interpolation filter type, interpolation filter tap, interpolation filter coefficient, motion vector size, representation accuracy of motion vector, transform type, transform size, information on whether primary (first) transform is used, information on whether secondary transform is used, primary transform index, secondary transform index , information on whether a residual signal exists, coding block pattern, coding block flag (CBF), quantization parameter, quantization parameter residual, quantization matrix, whether to apply an intra-frame loop filter, intra-frame loop filter coefficients, intra-frame loop filter taps, intra-frame loop filter shape / form, whether to apply a deblocking filter, deblocking filter coefficients, deblocking filter taps, deblocking filter strength, deblocking filter shape / form, whether to apply adaptive sample offset, adaptive sample offset value, adaptive sample offset category, adaptive sample offset type, whether to apply an adaptive loop filter, adaptive loop filter coefficients, adaptive loop filter taps, adaptive loop filter shape / form,Binarization / debinarization method, context model determination method, context model update method, whether to execute normal mode, whether to execute bypass mode, context binary bit, bypass binary bit, valid coefficient flag, last valid coefficient flag, encoding flag for unit of coefficient group, position of last valid coefficient, flag on whether the value of coefficient is greater than 1, flag on whether the value of coefficient is greater than 2, flag on whether the value of coefficient is greater than 3, information on remaining coefficient values, sign information, reconstructed luminance sample, reconstructed chrominance sample, residual luminance sample, residual chrominance sample, luminance transform coefficient, chrominance transform coefficient, quantized luminance level, quantized chrominance level, transform coefficient level scanning method, motion vector search area at decoder side domain size, shape of a motion vector search area at a decoder side, number of motion vector searches at a decoder side, information on a CTU size, information on a minimum block size, information on a maximum block size, information on a maximum block depth, information on a minimum block depth, image display / output order, slice identification information, slice type, slice partition information, tile identification information, tile type, tile partition information, tile group identification information, tile group type, tile group partition information, picture type, bit depth of input samples, bit depth of reconstructed samples, bit depth of residual samples, bit depth of transform coefficients, bit depth of quantization levels, and information on a luminance signal or information on a chrominance signal.

[0144] Here, signaling a flag or an index may mean entropy encoding the corresponding flag or index by an encoder and including it in a bitstream, and may mean entropy decoding the corresponding flag or index from the bitstream by a decoder.

[0145] When the encoding apparatus 100 performs encoding by inter-frame prediction, the encoded current image may be used as a reference image for another image that is subsequently processed. Therefore, the encoding apparatus 100 may reconstruct or decode the encoded current image, or store the reconstructed or decoded image as a reference image in the reference picture buffer 190.

[0146] The quantized level may be dequantized in the dequantization unit 160 or may be inversely transformed in the inverse transform unit 170. The dequantized or inversely transformed coefficient or the dequantized and inversely transformed coefficient may be added to the prediction block by the adder 175. By adding the dequantized or inversely transformed coefficient or the dequantized and inversely transformed coefficient to the prediction block, a reconstructed block may be generated. Here, the dequantized or inversely transformed coefficient or the dequantized and inversely transformed coefficient may mean a coefficient on which at least one of dequantization and inverse transformation is performed, and may mean a reconstructed residual block.

[0147] The reconstructed block may pass through the filter unit 180. The filter unit 180 may apply at least one of a deblocking filter, a sample adaptive offset (SAO), and an adaptive loop filter (ALF) to the reconstructed sample, the reconstructed block, or the reconstructed image. The filter unit 180 may be referred to as an in-loop filter.

[0148] The deblocking filter may remove block distortion generated in the boundary between blocks. In order to determine whether to apply the deblocking filter, it may be determined whether to apply the deblocking filter to the current block based on the samples included in the number of rows or columns included in the block. When the deblocking filter is applied to the block, another filter may be applied according to the required deblocking filter strength.

[0149] In order to compensate for the coding error, a suitable offset value may be added to the sample value by using sample adaptive offset. Sample adaptive offset can correct the offset of the deblocked image from the original image in units of samples. A method of applying the offset in consideration of edge information about each sample may be used, or a method of partitioning the samples of the image into a predetermined number of regions, determining the region to which the offset is applied, and applying the offset to the determined region may be used.

[0150] The adaptive loop filter may perform filtering based on a comparison result of a filtered reconstructed image and an original image. Samples included in an image may be partitioned into predetermined groups, a filter to be applied to each group may be determined, and differential filtering may be performed on each group. Information on whether ALF is applied may be signaled by a coding unit (CU), and the form and coefficient of ALF to be applied to each block may vary.

[0151] The reconstructed block or the reconstructed image that has passed through the filter unit 180 may be stored in the reference picture buffer 190. The reconstructed block processed by the filter unit 180 may be a part of the reference image. That is, the reference image is a reconstructed image composed of the reconstructed blocks processed by the filter unit 180. The stored reference image may be used later in inter-frame prediction or motion compensation.

[0152] Figure 2 is a block diagram showing the configuration of a decoding device according to an embodiment and to which the present invention is applied.

[0153] The decoding device 200 may be a decoder, a video decoding device, or an image decoding device.

[0154] Reference Figure 2 , the decoding device 200 may include an entropy decoding unit 210, a dequantization unit 220, an inverse transform unit 230, an intra-frame prediction unit 240, a motion compensation unit 250, an adder 255, a filter unit 260 and a reference picture buffer 270.

[0155] The decoding device 200 may receive a bit stream output from the encoding device 100. The decoding device 200 may receive a bit stream stored in a computer-readable recording medium, or may receive a bit stream streamed through a wired / wireless transmission medium. The decoding device 200 may decode the bit stream by using an intra mode or an inter mode. In addition, the decoding device 200 may generate a reconstructed image or a decoded image generated by decoding, and output the reconstructed image or the decoded image.

[0156] When the prediction mode used in decoding is the intra mode, the switch may be switched to the intra mode. Alternatively, when the prediction mode used in decoding is the inter mode, the switch may be switched to the inter mode.

[0157] The decoding device 200 can obtain a reconstructed residual block by decoding the input bit stream and generate a prediction block. When the reconstructed residual block and the prediction block are obtained, the decoding device 200 can generate a reconstructed block that becomes a decoding target by adding the reconstructed residual block to the prediction block. The decoding target block may be referred to as a current block.

[0158] The entropy decoding unit 210 may generate symbols by entropy decoding the bit stream according to the probability distribution. The generated symbols may include symbols in the form of quantized levels. Here, the entropy decoding method may be an inverse process of the above entropy encoding method.

[0159] In order to decode a transform coefficient level (a quantized level), the entropy decoding unit 210 may change a coefficient in a one-way vector form into a two-dimensional block form by using a transform coefficient scanning method.

[0160] The quantized level may be dequantized in the dequantization unit 220, or the quantized level may be inversely transformed in the inverse transform unit 230. The quantized level may be a result of dequantization or inverse transformation or both, and may be generated as a reconstructed residual block. Here, the dequantization unit 220 may apply a quantization matrix to the quantized level.

[0161] When the intra mode is used, the intra prediction unit 240 may generate a predicted block by performing spatial prediction on the current block, wherein the spatial prediction uses sample values ​​of a block that is adjacent to the decoding target block and has been decoded. When the inter mode is used, the motion compensation unit 250 may generate a prediction block by performing motion compensation on the current block, wherein the motion compensation uses a motion vector and a reference image stored in the reference picture buffer 270 .

[0162] The adder 255 can generate a reconstructed block by adding the reconstructed residual block to the prediction block. The filter unit 260 can apply at least one of a deblocking filter, a sample adaptive offset, and an adaptive loop filter to the reconstructed block or the reconstructed image. The filter unit 260 can output the reconstructed image. The reconstructed block or the reconstructed image can be stored in the reference picture buffer 270 and used when performing inter-frame prediction. The reconstructed block processed by the filter unit 260 can be a part of the reference image. That is, the reference image is a reconstructed image composed of the reconstructed blocks processed by the filter unit 260. The stored reference image can be used later in inter-frame prediction or motion compensation.

[0163] Figure 3 is a diagram schematically showing a partition structure of an image when the image is encoded and decoded. Figure 3 An example of partitioning a single unit into a plurality of subordinate units is schematically shown.

[0164] In order to efficiently partition an image, a coding unit (CU) may be used when encoding and decoding. A coding unit may be used as a basic unit when encoding / decoding an image. In addition, a coding unit may be used as a unit for distinguishing an intra prediction mode from an inter prediction mode when encoding / decoding an image. A coding unit may be a basic unit for prediction, transformation, quantization, inverse transformation, inverse quantization, or encoding / decoding processing of a transformation coefficient.

[0165] Reference Figure 3 , the image 300 is partitioned sequentially according to the maximum coding unit (LCU), and the LCU unit is determined as a partition structure. Here, the LCU may be used in the same meaning as the coding tree unit (CTU). Unit partitioning may mean partitioning a block associated with the unit. In the block partition information, information about the unit depth may be included. The depth information may indicate the number or degree of the unit being partitioned or both the number and degree of the unit being partitioned. A single unit may be partitioned into a plurality of subordinate units hierarchically associated with the depth information based on a tree structure. In other words, the unit and the subordinate units generated by partitioning the unit may correspond to a node and a child node of the node, respectively. Each of the partitioned subordinate units may have depth information. The depth information may be information indicating the size of a CU and may be stored in each CU. The unit depth indicates the number and / or degree associated with partitioning the unit. Therefore, the partition information of the subordinate unit may include information about the size of the subordinate unit.

[0166] The partition structure may represent the distribution of coding units (CUs) within the LCU 310. Such distribution may be determined based on whether a single CU is partitioned into multiple (including 2, 4, 8, 16, etc., positive integers equal to or greater than 2) CUs. The horizontal size and vertical size of the CU generated by partitioning may be half of the horizontal size and vertical size of the CU before partitioning, respectively, or may have sizes smaller than the horizontal size and vertical size before partitioning, respectively, according to the number of partitionings. The CU may be recursively partitioned into multiple CUs. By recursive partitioning, at least one of the height and width of the CU after partitioning may be reduced compared to at least one of the height and width of the CU before partitioning. Partitioning of the CU may be recursively performed until a predefined depth or a predefined size. For example, the depth of the LCU may be 0, and the depth of the minimum coding unit (SCU) may be a predefined maximum depth. Here, as described above, the LCU may be a coding unit having a maximum coding unit size, and the SCU may be a coding unit having a minimum coding unit size. Partitioning starts from the LCU 310, and when the horizontal size or the vertical size or both the horizontal size and the vertical size of the CU are reduced by partitioning, the CU depth increases by 1. For example, for each depth, the size of the non-partitioned CU may be 2N×2N. In addition, in the case of a partitioned CU, a CU of size 2N×2N may be partitioned into four CUs of size N×N. As the depth increases by 1, the size of N may be halved.

[0167] In addition, information on whether a CU is partitioned may be indicated by using partition information of the CU. The partition information may be 1-bit information. All CUs except the SCU may include partition information. For example, when the value of the partition information is a first value, the CU may not be partitioned, and when the value of the partition information is a second value, the CU may be partitioned.

[0168] Reference Figure 3 , an LCU with a depth of 0 may be a block of 64×64. 0 may be the minimum depth. An SCU with a depth of 3 may be a block of 8×8. 3 may be the maximum depth. A CU of a block of 32×32 and a CU of a block of 16×16 may be represented as depth 1 and depth 2, respectively.

[0169] For example, when a single coding unit is partitioned into four coding units, the horizontal size and vertical size of the four coding units partitioned may be half the size of the horizontal size and vertical size of the CU before being partitioned. In one embodiment, when a coding unit of size 32×32 is partitioned into four coding units, each of the four coding units partitioned may have a size of 16×16. When a single coding unit is partitioned into four coding units, it can be said that the coding unit can be partitioned into a quadtree form.

[0170] For example, when a coding unit is partitioned into two sub-coding units, the horizontal size or vertical size (width or height) of each of the two sub-coding units may be half of the horizontal size or vertical size of the original coding unit. For example, when a coding unit of size 32×32 is partitioned vertically into two sub-coding units, each of the two sub-coding units may have a size of 16×32. For example, when a coding unit of size 8×32 is partitioned horizontally into two sub-coding units, each of the two sub-coding units may have a size of 8×16. When a coding unit is partitioned into two sub-coding units, the coding unit may be said to be partitioned into two or partitioned according to a binary tree partition structure.

[0171] For example, when one coding unit is partitioned into three sub-coding units, the horizontal size or the vertical size of the coding unit may be partitioned at a ratio of 1:2:1, thereby generating three sub-coding units having a ratio of 1:2:1 in the horizontal size or the vertical size. For example, when a coding unit having a size of 16×32 is partitioned horizontally into three sub-coding units, the three sub-coding units may have sizes of 16×8, 16×16, and 16×8, respectively, in order from the uppermost sub-coding unit to the lowermost sub-coding unit. For example, when a coding unit having a size of 32×32 is partitioned vertically into three sub-coding units, the three sub-coding units may have sizes of 8×32, 16×32, and 8×32, respectively, in order from the left sub-coding unit to the right sub-coding unit. When one coding unit is partitioned into three sub-coding units, the coding unit may be said to be partitioned into three sub-coding units or partitioned according to a ternary tree partition structure.

[0172] exist Figure 3 , a coding tree unit (CTU) 320 is an example of a CTU to which a quadtree partition structure, a binary tree partition structure, and a ternary tree partition structure are all applied.

[0173] As described above, in order to partition a CTU, at least one of a quadtree partition structure, a binary tree partition structure, and a ternary tree partition structure may be applied. Various tree partition structures may be sequentially applied to a CTU according to a predetermined priority order. For example, a quadtree partition structure may be preferentially applied to a CTU. Coding units that can no longer be partitioned using a quadtree partition structure may correspond to leaf nodes of a quadtree. Coding units corresponding to leaf nodes of a quadtree may be used as root nodes of a binary and / or ternary tree partition structure. That is, coding units corresponding to leaf nodes of a quadtree may be further partitioned according to a binary tree partition structure or a ternary tree partition structure, or may not be further partitioned. Therefore, by preventing the coding blocks obtained from binary tree partitions or ternary tree partitions of coding units corresponding to leaf nodes of a quadtree from undergoing further quadtree partitions, block partitioning operations and / or operations of signaling partition information may be effectively performed.

[0174] The fact that the coding unit corresponding to the node of the quadtree is partitioned may be signaled using the four partition information. The four partition information having a first value (e.g., "1") may indicate that the current coding unit is partitioned according to the quadtree partition structure. The four partition information having a second value (e.g., "0") may indicate that the current coding unit is not partitioned according to the quadtree partition structure. The four partition information may be a flag having a predetermined length (e.g., one bit).

[0175] There may be no priority between binary tree partitioning and ternary tree partitioning. That is, the coding unit corresponding to the leaf node of the quadtree may further undergo any partitioning of the binary tree partitioning and the ternary tree partitioning. In addition, the coding unit generated by the binary tree partitioning or the ternary tree partitioning may undergo further binary tree partitioning or further ternary tree partitioning, or may not be further partitioned.

[0176] A tree structure in which there is no priority between binary tree partitions and ternary tree partitions is called a multi-type tree structure. A coding unit corresponding to a leaf node of a quadtree may be used as a root node of a multi-type tree. At least one of multi-type tree partition indication information, partition direction information, and partition tree information may be used to signal whether to partition a coding unit corresponding to a node of a multi-type tree. In order to partition a coding unit corresponding to a node of a multi-type tree, multi-type tree partition indication information, partition direction information, and partition tree information may be sequentially signaled.

[0177] The multi-type tree partition indication information having a first value (eg, '1') may indicate that the current coding unit will undergo multi-type tree partitioning. The multi-type tree partition indication information having a second value (eg, '0') may indicate that the current coding unit will not undergo multi-type tree partitioning.

[0178] When a coding unit corresponding to a node of a multi-type tree is further partitioned according to a multi-type tree partition structure, the coding unit may include partition direction information. The partition direction information may indicate in which direction the current coding unit will be partitioned for the multi-type tree partition. The partition direction information having a first value (e.g., "1") may indicate that the current coding unit will be partitioned vertically. The partition direction information having a second value (e.g., "0") may indicate that the current coding unit will be partitioned horizontally.

[0179] When the coding unit corresponding to the node of the multi-type tree is further partitioned according to the multi-type tree partition structure, the current coding unit may include partition tree information. The partition tree information may indicate a tree partition structure to be used to partition the node of the multi-type tree. The partition tree information having a first value (e.g., "1") may indicate that the current coding unit will be partitioned according to a binary tree partition structure. The partition tree information having a second value (e.g., "0") may indicate that the current coding unit will be partitioned according to a ternary tree partition structure.

[0180] The partition indication information, partition tree information and partition direction information may all be flags with a predetermined length (eg, one bit).

[0181] At least any one of the quadtree partition indication information, the multi-type tree partition indication information, the partition direction information, and the partition tree information may be entropy encoded / decoded. In order to entropy encode / decode those types of information, information about neighboring coding units adjacent to the current coding unit may be used. For example, there is a high probability that the partition type (partitioned or not partitioned, partition tree, and / or partition direction) of the left neighboring coding unit and / or the upper neighboring coding unit of the current coding unit is similar to the partition type of the current coding unit. Therefore, context information for entropy encoding / decoding the information about the current coding unit may be derived from the information about the neighboring coding units. The information about the neighboring coding units may include at least any one of the quadtree partition information, the multi-type tree partition indication information, the partition direction information, and the partition tree information.

[0182] As another example, among binary tree partitioning and ternary tree partitioning, binary tree partitioning may be preferentially performed. That is, the current coding unit may first undergo binary tree partitioning, and then the coding unit corresponding to the leaf node of the binary tree may be set as the root node for the ternary tree partitioning. In this case, for the coding unit corresponding to the node of the ternary tree, neither quadtree partitioning nor binary tree partitioning may be performed.

[0183] A coding unit that cannot be partitioned according to a quadtree partition structure, a binary tree partition structure, and / or a ternary tree partition structure becomes a basic unit for encoding, prediction, and / or transformation. That is, the coding unit cannot be further partitioned for prediction and / or transformation. Therefore, partition structure information and partition information for partitioning a coding unit into a prediction unit and / or a transformation unit may not exist in the bitstream.

[0184] However, when the size of the coding unit (ie, the basic unit for partitioning) is larger than the size of the maximum transform block, the coding unit may be recursively partitioned until the size of the coding unit is reduced to be equal to or smaller than the size of the maximum transform block. For example, when the size of the coding unit is 64×64 and when the size of the maximum transform block is 32×32, the coding unit may be partitioned into four 32×32 blocks for transforming. For example, when the size of the coding unit is 32×64 and the size of the maximum transform block is 32×32, the coding unit may be partitioned into two 32×32 blocks for transforming. In this case, the partitioning of the coding unit for transforming is not separately signaled, and the partitioning of the coding unit for transforming may be determined by comparison between the horizontal size or vertical size of the coding unit and the horizontal size or vertical size of the maximum transform block. For example, when the horizontal size (width) of the coding unit is larger than the horizontal size (width) of the maximum transform block, the coding unit may be vertically divided into two equal parts. For example, when the vertical size (height) of the coding unit is larger than the vertical size (height) of the maximum transform block, the coding unit may be horizontally divided into two equal parts.

[0185] Information on the maximum and / or minimum size of a coding unit and information on the maximum and / or minimum size of a transform block may be signaled or determined at an upper level of the coding unit. The upper level may be, for example, a sequence level, a picture level, a slice level, a tile group level, a tile block level, etc. For example, the minimum size of a coding unit may be determined to be 4×4. For example, the maximum size of a transform block may be determined to be 64×64. For example, the minimum size of a transform block may be determined to be 4×4.

[0186] Information on the minimum size of the coding unit corresponding to the leaf node of the quadtree (quadtree minimum size) and / or information on the maximum depth from the root node of the multi-type tree to the leaf node (maximum tree depth of the multi-type tree) may be signaled or determined at an upper level of the coding unit. For example, the upper level may be a sequence level, a picture level, a slice level, a parallel block group level, a parallel block level, etc. Information on the minimum size of the quadtree and / or information on the maximum depth of the multi-type tree may be signaled or determined for each of the intra-picture slice and the inter-picture slice.

[0187] The difference information between the size of the CTU and the maximum size of the transform block may be signaled or determined at the upper level of the coding unit. For example, the upper level may be a sequence level, a picture level, a slice level, a parallel block group level, a parallel block level, etc. The information of the maximum size of the coding unit corresponding to each node of the binary tree (hereinafter referred to as the maximum size of the binary tree) may be determined based on the size of the coding tree unit and the difference information. The maximum size of the coding unit corresponding to each node of the ternary tree (hereinafter referred to as the maximum size of the ternary tree) may vary according to the type of the slice. For example, for an intra-picture slice, the maximum size of the ternary tree may be 32×32. For example, for an inter-picture slice, the maximum size of the ternary tree may be 128×128. For example, the minimum size of the coding unit corresponding to each node of the binary tree (hereinafter referred to as the minimum size of the binary tree) and / or the minimum size of the coding unit corresponding to each node of the ternary tree (hereinafter referred to as the minimum size of the ternary tree) may be set to the minimum size of the coding block.

[0188] As another example, the maximum size of the binary tree and / or the maximum size of the ternary tree may be signaled or determined at the slice level. Alternatively, the minimum size of the binary tree and / or the minimum size of the ternary tree may be signaled or determined at the slice level.

[0189] According to the sizes and depth information of the above-mentioned various blocks, quad partition information, multi-type tree partition indication information, partition tree information and / or partition direction information may or may not be included in the bitstream.

[0190] For example, when the size of the coding unit is not greater than the minimum size of the quadtree, the coding unit does not include the quad partition information. The quad partition information may be inferred as the second value.

[0191] For example, when the size (horizontal size and vertical size) of the coding unit corresponding to the node of the multi-type tree is greater than the maximum size (horizontal size and vertical size) of the binary tree and / or the maximum size (horizontal size and vertical size) of the ternary tree, the coding unit may not be partitioned into two or three partitions. Therefore, the multi-type tree partition indication information may not be signaled, but the multi-type tree partition indication information may be inferred as the second value.

[0192] Optionally, when the size (horizontal size and vertical size) of the coding unit corresponding to the node of the multi-type tree is the same as the maximum size (horizontal size and vertical size) of the binary tree and / or is twice as large as the maximum size (horizontal size and vertical size) of the ternary tree, the coding unit may not be further partitioned into two or three partitions. Therefore, the multi-type tree partition indication information may not be sent by signal, but the multi-type tree partition indication information may be inferred as a second value. This is because when the coding unit is partitioned according to the binary tree partition structure and / or the ternary tree partition structure, a coding unit smaller than the minimum size of the binary tree and / or the minimum size of the ternary tree is generated.

[0193] Optionally, the binary tree partition or ternary tree partition may be limited based on the size of the virtual pipeline data unit (hereinafter, the pipeline buffer size). For example, when the coding unit is divided into sub-coding units that do not fit the pipeline buffer size by the binary tree partition or ternary tree partition, the corresponding binary tree partition or ternary tree partition may be limited. The pipeline buffer size may be the size of the maximum transform block (e.g., 64×64). For example, when the pipeline buffer size is 64×64, the following division may be limited.

[0194] - N×M (N and / or M is 128) ternary tree partitions for coding units - 128×N (N<=64) binary tree partitions in the horizontal direction for coding units - N×128 (N<=64) binary tree partitions in the vertical direction for coding units Optionally, when the depth of the coding unit corresponding to the node of the multi-type tree is equal to the maximum depth of the multi-type tree, the coding unit may not be further partitioned into two and / or three partitions. Therefore, the multi-type tree partition indication information may not be sent by a signal, but the multi-type tree partition indication information may be inferred as the second value.

[0195] Optionally, only when at least one of vertical binary tree partitioning, horizontal binary tree partitioning, vertical ternary tree partitioning, and horizontal ternary tree partitioning is possible for a coding unit corresponding to a node of a multi-type tree, a multi-type tree partition indication information may be sent by a signal. Otherwise, the coding unit may not be partitioned into two and / or three partitions. Therefore, the multi-type tree partition indication information may not be sent by a signal, but the multi-type tree partition indication information may be inferred as a second value.

[0196] Optionally, only when both vertical binary tree partitioning and horizontal binary tree partitioning or both vertical ternary tree partitioning and horizontal ternary tree partitioning are possible for the coding unit corresponding to the node of the multi-type tree, the partition direction information can be sent by signal. Otherwise, the partition direction information may not be sent by signal, but the partition direction information may be inferred as a value indicating a possible partition direction.

[0197] Optionally, only when both vertical binary tree partitioning and vertical ternary tree partitioning or both horizontal binary tree partitioning and horizontal ternary tree partitioning are possible for a coding tree corresponding to a node of a multi-type tree, partition tree information may be signaled. Otherwise, partition tree information may not be signaled, but the partition tree information may be inferred as a value indicating a possible partition tree structure.

[0198] Figure 4 is a diagram illustrating an intra prediction process.

[0199] Figure 4 The arrows from the center to the outside in FIG. 1 represent the prediction direction of the intra prediction mode.

[0200] Intra-frame encoding and / or decoding may be performed by using reference samples of neighboring blocks of the current block. The neighboring blocks may be reconstructed neighboring blocks. For example, intra-frame encoding and / or decoding may be performed by using values ​​of reference samples or encoding parameters included in the reconstructed neighboring blocks.

[0201] The prediction block may represent a block generated by performing intra prediction. The prediction block may correspond to at least one of a CU, a PU, and a TU. The unit of the prediction block may have a size of one of a CU, a PU, and a TU. The prediction block may be a square block of a size of 2×2, 4×4, 16×16, 32×32, or 64×64, etc., or may be a rectangular block of a size of 2×8, 4×8, 2×16, 4×16, and 8×16, etc.

[0202] Intra-prediction may be performed according to an intra-prediction mode for the current block. The number of intra-prediction modes that the current block may have may be a fixed value, and may be a value determined differently according to properties of the prediction block. For example, the properties of the prediction block may include the size of the prediction block, the shape of the prediction block, and the like.

[0203] Regardless of the block size, the number of intra-frame prediction modes can be fixed to N. Alternatively, the number of intra-frame prediction modes can be 3, 5, 9, 17, 34, 35, 36, 65 or 67, etc. Optionally, the number of intra-frame prediction modes can vary according to the block size or the color component type or both the block size and the color component type. For example, the number of intra-frame prediction modes can vary depending on whether the color component is a luminance signal or a chrominance signal. For example, as the block size becomes larger, the number of intra-frame prediction modes can increase. Optionally, the number of intra-frame prediction modes of the luminance component block can be greater than the number of intra-frame prediction modes of the chrominance component block.

[0204] The intra prediction mode may be a non-angle mode or an angle mode. The non-angle mode may be a DC mode or a planar mode, and the angle mode may be a prediction mode having a specific direction or angle. The intra prediction mode may be represented by at least one of a mode number, a mode value, a mode number, a mode angle, and a mode direction. The number of intra prediction modes may be M, which is greater than 1, including non-angle modes and angle modes. In order to perform intra prediction on a current block, a step of determining whether a sample included in a reconstructed neighboring block can be used as a reference sample of the current block may be performed. When there are samples that cannot be used as reference samples of the current block, a value obtained by copying or interpolating at least one sample value included in the reconstructed neighboring block, or by both copying and interpolating, may be used to replace the unavailable sample value of the sample, so that the replaced sample value is used as the reference sample of the current block.

[0205] Figure 7 is a diagram showing reference samples that can be used for intra prediction.

[0206] like Figure 7 As shown in , at least one of the reference sample line 0 to the reference sample line 3 can be used for intra prediction of the current block. Figure 7 In , the samples of fragment A and fragment F can be filled with the samples of the closest fragment B and fragment E, respectively, instead of retrieving from the reconstructed neighboring blocks. The index information indicating the reference sample line to be used for intra prediction of the current block can be sent by signaling. For example, in Figure 7 In the example, reference sample line indicators 0, 1, and 2 may be signaled as index information indicating reference sample line 0, reference sample line 1, and reference sample line 2. When the upper boundary of the current block is the boundary of the CTU, only reference sample line 0 may be available. Therefore, in this case, index information may not be signaled. When reference sample lines other than reference sample line 0 are used, filtering for a prediction block, which will be described later, may not be performed.

[0207] When intra prediction is performed, a filter may be applied to at least one of a reference sample and a prediction sample based on an intra prediction mode and a current block size.

[0208] In the case of the planar mode, when generating a prediction block of the current block, according to the position of the prediction target sample within the prediction block, the sample value of the prediction target sample may be generated by using the weighted sum of the upper reference sample and the left reference sample of the current sample and the upper right reference sample and the lower left reference sample of the current block. In addition, in the case of the DC mode, when generating the prediction block of the current block, the average value of the upper reference sample and the left reference sample of the current block may be used. In addition, in the case of the angular mode, the prediction block may be generated by using the upper reference sample, the left reference sample, the upper right reference sample and / or the lower left reference sample of the current block. In order to generate the prediction sample value, interpolation of real number units may be performed.

[0209] In the case of intra prediction between color components, a prediction block of a current block of a second color component may be generated based on a corresponding reconstruction block of a first color component. For example, the first color component may be a luminance component, and the second color component may be a chrominance component. For intra prediction between color components, parameters of a linear model between the first color component and the second color component may be derived based on a template. The template may include upper and / or left neighboring samples of the current block and upper and / or left neighboring samples of a reconstruction block of the first color component corresponding thereto. For example, the sample value of the first color component having the maximum value among the samples in the template and the sample value of the second color component corresponding thereto, and the sample value of the first color component having the minimum value among the samples in the template and the sample value of the second color component corresponding thereto may be used to derive the parameters of the linear model. When deriving the parameters of the linear model, the corresponding reconstruction block may be applied to the linear model to generate a prediction block of the current block. Depending on the video format, subsampling may be performed on the neighboring samples of the reconstruction block of the first color component and the corresponding reconstruction block. For example, when one sample of the second color component corresponds to four samples of the first color component, the four samples of the first color component may be subsampled to calculate one corresponding sample. In this case, parameter derivation of the linear model and intra prediction between color components may be performed based on the corresponding subsampled samples. Whether to perform intra prediction between color components and / or the range of the template may be signaled as an intra prediction mode.

[0210] The current block may be partitioned into two sub-blocks or four sub-blocks in the horizontal direction or the vertical direction. The partitioned sub-blocks may be reconstructed sequentially. That is, intra prediction may be performed on the sub-block to generate a sub-prediction block. In addition, inverse quantization and / or inverse transformation may be performed on the sub-block to generate a sub-residual block. The reconstructed sub-block may be generated by adding the sub-prediction block to the sub-residual block. The reconstructed sub-block may be used as a reference sample for intra prediction of a subsequent sub-block. The sub-block may be a block including a predetermined number (e.g., 16) or more samples. Thus, for example, when the current block is an 8×4 block or a 4×8 block, the current block may be partitioned into two sub-blocks. In addition, when the current block is a 4×4 block, the current block may not be partitioned into sub-blocks. When the current block has other sizes, the current block may be partitioned into four sub-blocks. Information on whether intra prediction is performed based on sub-blocks and / or partition directions (horizontal or vertical) may be sent by a signal. Intra prediction based on sub-blocks may be performed only when reference sample line 0 is used. When subblock-based intra prediction is performed, filtering for a prediction block, which will be described later, may not be performed.

[0211] The final prediction block can be generated by performing filtering on the prediction block predicted by the intra-frame. Filtering can be performed by applying predetermined weights to the filtering target samples, the left reference samples, the upper reference samples and / or the upper left reference samples. The weights and / or reference samples (range, position, etc.) used for filtering can be determined based on at least one of the block size, the intra-frame prediction mode and the position of the filtering target samples in the prediction block. Filtering can be performed only in the case of a predetermined intra-frame prediction mode (e.g., DC, plane, vertical, horizontal, diagonal and / or adjacent diagonal mode). The adjacent diagonal mode can be a mode in which k is added to the diagonal mode or k is subtracted from the diagonal mode. For example, k can be a positive integer of 8 or less.

[0212] The intra-frame prediction mode of the current block may be entropy encoded / decoded by predicting the intra-frame prediction mode of a block existing adjacent to the current block. When the intra-frame prediction mode of the current block is the same as that of the neighboring block, information that the intra-frame prediction mode of the current block is the same as that of the neighboring block may be signaled by using predetermined flag information. In addition, indicator information of the intra-frame prediction mode that is the same as the intra-frame prediction mode of the current block among the intra-frame prediction modes of multiple neighboring blocks may be signaled. When the intra-frame prediction mode of the current block is different from that of the neighboring block, the intra-frame prediction mode information of the current block may be entropy encoded / decoded by performing entropy encoding / decoding based on the intra-frame prediction mode of the neighboring block.

[0213] Figure 5 is a diagram illustrating an embodiment of an inter-picture prediction process.

[0214] exist Figure 5 In , a rectangle can represent a picture. Figure 5In FIG. 1 , the arrow indicates the prediction direction. According to the encoding type of the picture, the picture can be classified into an intra picture (I picture), a predicted picture (P picture) and a bi-predicted picture (B picture).

[0215] An I picture may be encoded by intra prediction without requiring inter-picture prediction. A P picture may be encoded by inter-picture prediction using a reference picture existing in one direction (i.e., forward or backward) relative to the current block. A B picture may be encoded by inter-picture prediction using a reference picture existing in two directions (i.e., forward and backward) relative to the current block. When inter-picture prediction is used, the encoder may perform inter-picture prediction or motion compensation, and the decoder may perform corresponding motion compensation.

[0216] Hereinafter, embodiments of inter-picture prediction will be described in detail.

[0217] Reference pictures and motion information may be used to perform inter-picture prediction or motion compensation.

[0218] The motion information of the current block may be derived during inter-picture prediction by each of the encoding device 100 and the decoding device 200. The motion information of the current block may be derived by using the motion information of a reconstructed neighboring block, the motion information of a co-located block (also referred to as a col block or a co-located block), and / or the motion information of a block adjacent to the co-located block. The co-located block may represent a block in a previously reconstructed co-located picture (also referred to as a col picture or a co-located picture) that is spatially located at the same position as the current block. The co-located picture may be one of the one or more reference pictures included in the reference picture list.

[0219] The derivation method of motion information may be different according to the prediction mode of the current block. For example, the prediction modes applied to inter prediction include AMVP mode, merge mode, skip mode, merge mode with motion vector difference, sub-block merge mode, geometric partition mode, combined inter-intra prediction mode, affine mode, etc. Here, the merge mode may be referred to as motion merge mode.

[0220] For example, when AMVP is used as a prediction mode, at least one of a motion vector of a reconstructed neighboring block, a motion vector of a co-located block, a motion vector of a block adjacent to the co-located block, and a (0,0) motion vector may be determined as a motion vector candidate for the current block, and a motion vector candidate list may be generated by using the motion vector candidates. The motion vector candidate for the current block may be derived by using the generated motion vector candidate list. The motion information of the current block may be determined based on the derived motion vector candidate. The motion vector of the co-located block or the motion vector of a block adjacent to the co-located block may be referred to as a temporal motion vector candidate, and the motion vector of the reconstructed neighboring block may be referred to as a spatial motion vector candidate.

[0221] The encoding device 100 may calculate a motion vector difference (MVD) between a motion vector of a current block and a motion vector candidate, and may perform entropy encoding on the motion vector difference (MVD). In addition, the encoding device 100 may perform entropy encoding on a motion vector candidate index and generate a bitstream. The motion vector candidate index may indicate the best motion vector candidate among the motion vector candidates included in the motion vector candidate list. The decoding device may perform entropy decoding on the motion vector candidate index included in the bitstream, and may select a motion vector candidate for a decoding target block from the motion vector candidates included in the motion vector candidate list by using the entropy-decoded motion vector candidate index. In addition, the decoding device 200 may add the entropy-decoded MVD to the motion vector candidate extracted by entropy decoding, thereby deriving a motion vector of the decoding target block.

[0222] In addition, the encoding apparatus 100 may perform entropy encoding on the resolution information of the calculated MVD. The decoding apparatus 200 may adjust the resolution of the entropy-decoded MVD using the MVD resolution information.

[0223] In addition, the encoding device 100 calculates a motion vector difference (MVD) between a motion vector in the current block and a motion vector candidate based on an affine model, and performs entropy encoding on the MVD. The decoding device 200 derives a motion vector based on each sub-block by deriving an affine controlled motion vector of a decoding target block according to the sum of the entropy-decoded MVD and the affine controlled motion vector candidate.

[0224] The bitstream may include a reference picture index indicating a reference picture. The reference picture index may be entropy encoded by the encoding apparatus 100 and then signaled as a bitstream to the decoding apparatus 200. The decoding apparatus 200 may generate a prediction block of a decoding target block based on the derived motion vector and the reference picture index information.

[0225] Another example of a method of deriving motion information of a current block may be a merge mode. The merge mode may represent a method of merging motions of multiple blocks. The merge mode may represent a mode of deriving motion information of a current block from motion information of neighboring blocks. When the merge mode is applied, the motion information of reconstructed neighboring blocks and / or the motion information of the same-positioned blocks may be used to generate a merge candidate list. The motion information may include at least one of a motion vector, a reference picture index, and an inter-picture prediction indicator. The prediction indicator may indicate unidirectional prediction (L0 prediction or L1 prediction) or bidirectional prediction (L0 prediction and L1 prediction).

[0226] The merge candidate list may be a list of stored motion information. The motion information included in the merge candidate list may be at least one of the following: motion information of a neighboring block adjacent to the current block (spatial merge candidate), motion information of a co-located block of the current block in a reference picture (temporal merge candidate), new motion information generated by combining motion information present in the merge candidate list, motion information of a block encoded / decoded before the current block (history-based merge candidate), and a zero merge candidate.

[0227] The encoding device 100 may generate a bitstream by performing entropy encoding on at least one of a merge flag and a merge index, and may signal the bitstream to the decoding device 200. The merge flag may be information indicating whether a merge mode is performed for each block, and the merge index may be information indicating which neighboring block among neighboring blocks of the current block is a merge target block. For example, the neighboring blocks of the current block may include a left neighboring block located on the left side of the current block, an upper neighboring block arranged above the current block, and a temporal neighboring block temporally adjacent to the current block.

[0228] In addition, the encoding device 100 performs entropy encoding on the correction information for correcting the motion vector in the motion information of the merge candidate, and transmits it to the decoding device 200 by signal. The decoding device 200 may correct the motion vector of the merge candidate selected by the merge index based on the correction information. Here, the correction information may include at least one of information on whether to perform correction, correction direction information, and correction size information. As described above, the prediction mode in which the motion vector of the merge candidate is corrected based on the correction information transmitted by the signal may be referred to as a merge mode with a motion vector difference.

[0229] The skip mode may be a mode in which the motion information of the neighboring blocks is applied to the current block as it is. When the skip mode is applied, the encoding apparatus 100 may perform entropy encoding on information of the fact of which block's motion information is to be used as the motion information of the current block to generate a bitstream, and may signal the bitstream to the decoding apparatus 200. The encoding apparatus 100 may not signal a syntax element regarding at least any one of the motion vector difference information, the coded block flag, and the transform coefficient level to the decoding apparatus 200.

[0230] The subblock merge mode may represent a mode for deriving motion information in units of subblocks of a coding block (CU). When the subblock merge mode is applied, the subblock merge candidate list may be generated using motion information of a subblock co-located with the current subblock in a reference image (subblock-based temporal merge candidates) and / or affine control point motion vector merge candidates.

[0231] The geometric partition mode may denote a mode in which motion information is derived by partitioning the current block in a predetermined direction, each prediction sample is derived using each of the derived motion information, and a prediction sample of the current block is derived by weighting each of the derived prediction samples.

[0232] The inter-intra combined prediction mode may mean a mode of deriving a prediction sample of a current block by weighting a prediction sample generated by inter prediction and a prediction sample generated by intra prediction.

[0233] The decoding apparatus 200 may correct the derived motion information by itself. The decoding apparatus 200 may search for a predetermined area based on a reference block indicated by the derived motion information, and derive motion information having a minimum SAD as the corrected motion information.

[0234] The decoding apparatus 200 may compensate for prediction samples derived through inter-frame prediction using optical flow.

[0235] Figure 6 is a diagram illustrating transform and quantization processing.

[0236] like Figure 6 As shown in , a transform process and / or a quantization process is performed on the residual signal to generate a quantized level signal. The residual signal is the difference between the original block and the prediction block (i.e., an intra-frame prediction block or an inter-frame prediction block). The prediction block is a block generated by intra-frame prediction or inter-frame prediction. The transform can be a primary transform, a secondary transform, or both a primary transform and a secondary transform. The primary transform of the residual signal generates transform coefficients, and the secondary transform of the transform coefficients generates secondary transform coefficients.

[0237] At least one scheme selected from various predefined transform schemes is used to perform the primary transform. For example, examples of the predefined transform schemes include discrete cosine transform (DCT), discrete sine transform (DST) and Karhunen-Loève transform (KLT). The transform coefficients generated by the primary transform may undergo a secondary transform. The transform scheme used for the primary transform and / or the secondary transform may be determined based on the coding parameters of the current block and / or the neighboring blocks of the current block. Optionally, transform information indicating the transform scheme may be sent by a signal. DCT-based transforms may include, for example, DCT-2, DCT-8, etc. DST-based transforms may include, for example, DST-7.

[0238] A quantized level signal (quantized coefficient) may be generated by performing quantization on a residual signal or on a result of performing a primary transform and / or a secondary transform. Depending on the intra prediction mode of the block or the block size / shape, the quantized level signal may be scanned according to at least one of diagonal upper right scanning, vertical scanning, and horizontal scanning. For example, when the coefficients are scanned according to a diagonal upper right scan, the coefficients in block form are changed to a one-dimensional vector form. In addition to the diagonal upper right scan, horizontal scanning that scans the coefficients in two-dimensional block form horizontally or vertical scanning that scans the coefficients in two-dimensional block form vertically may be used, depending on the intra prediction mode and / or the size of the transform block. The scanned quantized level coefficients may be entropy encoded for insertion into a bitstream.

[0239] The decoder performs entropy decoding on the bit stream to obtain quantized level coefficients. The quantized level coefficients can be arranged in a two-dimensional block form by inverse scanning. For the inverse scanning, at least one of diagonal upper right scanning, vertical scanning, and horizontal scanning can be used.

[0240] The quantized level coefficients may then be dequantized, then inversely transformed at a secondary level as required, and finally inversely transformed at a primary level as required to generate a reconstructed residual signal.

[0241] Inverse mapping in the dynamic range can be performed for the luminance component reconstructed by intra-frame prediction or inter-frame prediction before in-loop filtering. The dynamic range can be divided into 16 equal segments, and the mapping function for each segment can be sent by signal. The mapping function can be sent by signal at the slice level or parallel block group level. The inverse mapping function for performing inverse mapping can be derived based on the mapping function. In-loop filtering, reference picture storage and motion compensation are performed in the inverse mapping area, and the prediction block generated by inter-frame prediction is converted to the mapping area via mapping using the mapping function, and then used to generate the reconstructed block. However, since intra-frame prediction is performed in the mapping area, the prediction block generated by intra-frame prediction can be used to generate the reconstructed block without mapping / inverse mapping.

[0242] When the current block is a residual block of a chroma component, the residual block can be converted to an inverse mapping area by performing scaling on the chroma component of the mapping area. The availability of scaling can be signaled at the slice level or the parallel block group level. Scaling can be applied only when mapping for the luminance component is available and the division of the luminance component and the division of the chroma component follow the same tree structure. Scaling can be performed based on the average value of the sample value of the luminance prediction block corresponding to the chroma block. In this case, when the current block uses inter-frame prediction, the luminance prediction block can represent the mapped luminance prediction block. The value required for scaling can be derived by using the index reference lookup table of the fragment to which the average value of the sample value of the luminance prediction block belongs. Finally, the residual block can be converted to an inverse mapping area by scaling the residual block using the derived value. Then, chroma component block recovery, intra-frame prediction, inter-frame prediction, in-loop filtering, and reference picture storage can be performed in the inverse mapping area.

[0243] Information indicating whether mapping / inverse mapping of luma components and chroma components is available may be signaled through a sequence parameter set.

[0244] The prediction block of the current block may be generated based on a block vector indicating the displacement between the current block and the reference block in the current picture. In this way, the prediction mode for generating the prediction block with reference to the current picture is called an intra-block copy (IBC) mode. The IBC mode may be applied to M×N (M<=64, N<=64) coding units. The IBC mode may include a skip mode, a merge mode, an AMVP mode, and the like. In the case of the skip mode or the merge mode, a merge candidate list is constructed, and a merge index is signaled so that a merge candidate can be specified. The block vector of the specified merge candidate may be used as the block vector of the current block. The merge candidate list may include at least one of a spatial candidate, a history-based candidate, a candidate based on the average of two candidates, and a zero merge candidate. In the case of the AMVP mode, a difference block vector may be signaled. In addition, a prediction block vector may be derived from the left neighboring block and the upper neighboring block of the current block. The index of the neighboring block to be used may be signaled. The prediction block in the IBC mode is included in the current CTU or the left CTU and is limited to blocks in the reconstructed area. For example, the value of the block vector may be limited so that the prediction block of the current block is located in the region of three 64×64 blocks preceding the 64×64 block to which the current block belongs in the encoding / decoding order. By limiting the value of the block vector in this way, the memory consumption and device complexity of the implementation according to the IBC mode may be reduced.

[0245] According to one embodiment, the deblocking filtering process may not be applied to the edges described below.

[0246] The edge corresponding to the border of the picture When the information indicating whether filtering is performed on the virtual boundary (eg, pps_loop_filter_across_virtual_boundaries_disabled_flag) has the first value of 1, the same edge as the virtual boundary of the picture.

[0247] When the information indicating whether filtering is performed on the tile boundary (eg, loop_filter_across_bricks_enabled_flag) has the second value of 0, the same edge as the tile boundary.

[0248] When the information indicating whether filtering is performed on the slice boundary (eg, loop_filter_slices_enabled_flag) has the second value of 0, the same edge as the slice boundary.

[0249] When the information indicating whether deblocking filtering is performed on a slice (eg, slice_deblocking_filter_disabled_flag) has a first value of 1, the same edge as an upper boundary or a left boundary of the slice.

[0250] When slice_deblocking_filter_disabled_flag is 1, at the edge of the slice.

[0251] Edges that are not related to the 8×8 grid boundary of the component An edge within the luma component when intra_bdpcm_flag is 1 on both sides of the edge.

[0252] The edge of the chroma transform block, not the edge of the associated transform unit When a single picture is divided into different areas, filtering the boundaries that distinguish the areas may cause blurring. As a result, the quality of an image (such as a 360-degree image) or a sub-picture composed of different frames may be reduced. Therefore, when a boundary that can distinguish different areas is signaled as virtual boundary information, a loop filter (deblocking, SAO, ALF) may not be applied to the interface across the virtual boundary.

[0253] Figure 8 is a diagram showing signaling of a conventional number of horizontal virtual borders and vertical virtual borders, an X position of a horizontal virtual border, and a Y position of a vertical virtual border.

[0254] refer to Figure 8 In conventional technology, information of a distinguishable virtual boundary in a picture parameter set (PPS) may be transmitted by a signal.

[0255] The number of vertical virtual borders, the X position of the vertical virtual borders, the number of horizontal virtual borders, and the Y position of the horizontal virtual borders may be signaled.

[0256] When information indicating whether filtering is performed on a virtual boundary (eg, pps_loop_filter_across_virtual_boundaries_disabled_flag) in the PPS has a first value of 1, the following information may be signaled.

[0257] For example, information indicating the number of vertical virtual boundaries (eg, pps_num_ver_virtual_boundaries) may be signaled.

[0258] Here, the information may have a value from 0 to 3. Therefore, the number of vertical virtual boundaries may be up to three.

[0259] Furthermore, for example, information indicating the vertical positions of i virtual boundaries may be signaled (eg, pps_virtual_boundries_pos_x[i]).

[0260] Here, the information may have a value from 1 to Ceil(pic_width_in_luma_sample / 8) - 1. In other words, the X position value of the virtual border may be signaled as the picture width divided by 8.

[0261] In addition, for example, information indicating the number of horizontal virtual boundaries (eg, pps_num_hor_virtual_boundaries) may be signaled.

[0262] Here, the information may have a value from 0 to 3. Therefore, the number of horizontal virtual boundaries may be up to three.

[0263] In addition, for example, information indicating the horizontal positions of i virtual boundaries may be signaled (eg, pps_virtual_boundaries_pos_y[i]).

[0264] Here, the information may have a value from 1 to Ceil(pic_height_in_luma_sample / 8)-1.

[0265] In other words, the Y position value of the virtual border may be signaled as the picture height divided by 8.

[0266] An example of the derivation and constraints of ppsVirtualBoundariesPosX[i] can be described as follows.

[0267] ppsVirtualBoundariesPosX[i]=pps_virtual_boundaries_pos_x[i]×8 Constraint: The distance between two vertical virtual borders should be at least equal to or greater than CtbSizeY.

[0268] Additionally, an example of the derivation and constraints of ppsVirtualBoundariesPosY[i] can be described as follows.

[0269] ppsVirtualBoundariesPosY[i]=pps_virtual_boundaries_pos_y[i]×8 Constraint: The distance between two horizontal virtual borders should be equal to or greater than at least CtbSizeX.

[0270] Fig. 9 is a diagram illustrating a method of setting a virtual boundary through EdgeFlag in a transform block according to an embodiment of the present invention.

[0271] refer to Fig. 9 , when determining the x-coordinate and the y-coordinate of the boundary, it can be determined whether to perform filtering by checking whether a virtual boundary exists in the transform block.

[0272] Whether there is filtering of a virtual boundary may be determined by setting edgeFlag[x][y] (ie, x coordinate and y coordinate of the boundary) according to edgeType (EDGE_VER, EDGE_HOR) which is information showing the boundary type.

[0273] Furthermore, maxFilterLengthPs and / or maxFilterLengthQs may be additionally derived.

[0274] The position of the virtual boundary may include at least one of a first position of a vertical virtual boundary and a second position of a horizontal virtual boundary.

[0275] Here, the first position may be determined based on at least one of first position information, width information of the image unit, information about the number of vertical virtual boundaries belonging to the image unit, and a predetermined first offset.

[0276] Here, the first offset may mean a horizontal offset.

[0277] For example, the first offset may be specified as a distance from a left boundary or a right boundary of the screen to the current virtual boundary, or as a distance from a previous vertical virtual boundary within the screen to the current virtual boundary.

[0278] Additionally, for example, the first offset may be encoded as a difference between a distance to a current virtual boundary and a distance to a previous vertical virtual boundary.

[0279] In addition, for example, the first offset may be specified as a distance from at least one vertical virtual boundary among the plurality of vertical virtual boundaries to the current virtual boundary.

[0280] The second position may be determined based on at least one of the second position information, height information of the image unit, information about the number of horizontal virtual boundaries belonging to the image unit, and a predetermined second offset.

[0281] Here, the second offset may represent a vertical offset.

[0282] For example, the second offset may be specified as a distance from a top or bottom boundary of the screen to the current virtual boundary, or as a distance from a previous horizontal virtual boundary within the screen to the current virtual boundary.

[0283] Additionally, for example, the second offset may be encoded as a difference between a distance to a current virtual boundary and a distance to a previous horizontal virtual boundary.

[0284] In addition, for example, the second offset may be specified as a distance from at least one horizontal virtual boundary among the plurality of horizontal virtual boundaries to the current virtual boundary.

[0285] In addition, the above-mentioned image unit may represent a picture, a slice, a parallel block, a sub-parallel block or a sub-picture. The position, information about the first / second position, information about the width, information about the number, and all or some offsets may be sent with a signal in the encoder or derived in the decoder. Here, the derivation may be performed based on the coding parameters sent with a signal in the encoder or based on a predefined value in the decoder. Here, the coding parameters may include the following information: whether to use a boundary, whether there is a boundary, the number of boundaries, the width / height of the picture, the shape of the strip, whether the picture is divided into parallel blocks or sub-parallel blocks / sub-pictures, the number of parallel blocks or sub-parallel blocks, the number of sub-pictures, and the size of the coding tree block (CTB). Here, the boundary may represent a virtual boundary, a slice boundary, a parallel block boundary, a coding block boundary, and a transform block boundary.

[0286] For example, based on information on whether a virtual boundary of the current block exists, information on the number of virtual boundaries may be determined.

[0287] In addition, for example, based on the information about the number of virtual boundaries, information about the position of the virtual boundary may be determined.

[0288] In addition, for example, the information on whether the virtual boundary exists may be determined based on the information on whether the virtual boundary is used.

[0289] Here, information on whether a virtual boundary exists, information on whether a virtual boundary is used, and information on the number of virtual boundaries may be signaled in a sequence parameter set (SPS) and a picture header (PH).

[0290] In addition, for example, the number of virtual borders may represent the number of horizontal virtual borders or the number of vertical virtual borders.

[0291] In addition, for example, the information about the position of the virtual boundary may represent information about the position of a horizontal virtual boundary or information about the position of a vertical virtual boundary.

[0292] In addition, for example, the position of the virtual boundary for the current block may be obtained by applying a predetermined weight to the information on the position of the virtual boundary.

[0293] Here, the predetermined weight may be a positive integer greater than 0, and may be 8, for example.

[0294] At least one of information about the number of virtual boundaries and information about the position of the virtual boundary (hereinafter, referred to as virtual boundary information) can be adaptively obtained based on a first flag indicating whether to signal the virtual boundary information. The first flag can be defined as a single flag regardless of the horizontal / vertical direction, or defined for each of the horizontal / vertical directions, such as the virtual boundary information.

[0295] The above-mentioned first flag and / or virtual boundary information may be information encoded / decoded at the first high level or at the second high level. For example, the first high level may represent a video parameter set or a sequence parameter set, and the second high level indicating a level lower than the first high level may represent a picture parameter set, a picture header, or a slice header. For ease of explanation, it is assumed that the first high level and the second high level are a sequence parameter set (SPS) and a picture header (PH), respectively. The first flag and virtual boundary information encoded / decoded in the SPS may be referred to as SPS information, and the first flag and virtual boundary information encoded / decoded in the PH may be referred to as PH information.

[0296] The SPS information and the PH information may be adaptively signaled based on a flag (hereinafter, referred to as a second flag) indicating whether the application of the loop filter is limited on a virtual boundary within the picture. For example, when the second flag is 1, it indicates that the disabling of the loop filter may be applied to the virtual boundary. On the other hand, when the second flag is 0, it indicates that the disabling of the loop filter is not applied to the virtual boundary. Therefore, only when the second flag is 1, at least one of the SPS information and the PH information may be signaled.

[0297] In addition, in order to specify the virtual boundary in the current picture, any one of the SPS information and the PH information may be selectively used. For selective use, a separate flag indicating whether to use which of the SPS information and the PH information may be defined, and the first flag in the above-mentioned SPS information may be used. For example, when there is virtual boundary information of the SPS level according to the first flag of the SPS information, the position of the virtual boundary or the virtual boundary within the current picture may be specified based on the virtual boundary information of the SPS information. On the other hand, when there is no virtual boundary information of the SPS level according to the first flag of the SPS information, the position of the virtual boundary or the virtual boundary within the current picture may be specified based on the virtual boundary information in the PH information. Here, it may be assumed that there is virtual boundary information of the PH level according to the first flag of the PH information.

[0298] Hereinafter, a method of signaling evenly spaced virtual boundaries will be described.

[0299] Fig.10 is a diagram illustrating setting a vertical virtual boundary according to an embodiment of the present invention.

[0300] Reference Fig.10 , the number of vertical virtual boundaries may be 2, and pic_width_in_luma_sample, i.e., the picture width in luma samples, may be 900. The x coordinate of the vertical virtual boundary may be obtained by (i+1)×(pic_width_in_luma_sample / (pps_num_ver_virtual_boundaries+1)). Here, when i is 0, the x coordinate of the vertical virtual boundary may be 300. When i is 1, the x coordinate of the vertical virtual boundary may be 600.

[0301] Fig.11 is a diagram illustrating setting a horizontal virtual boundary according to an embodiment of the present invention.

[0302] Reference Fig.11 , the number of horizontal virtual boundaries may be 1, and pic_width_in_luma_sample, the picture height in luma samples, may be 600. The y coordinate of the horizontal virtual boundary may be obtained by (i+1)×(pic_height_in_luma_sample / (pps_num_hor_virtual_boundaries+1)). In this case, when i is 0, the y coordinate of the horizontal virtual boundary may be 300.

[0303] Fig.12 is a diagram showing a method of representing a brightness sample in a picture according to an embodiment of the present invention. Fig.10 and Fig.11Illustration of the vertical virtual boundary and the horizontal virtual boundary described in .

[0304] Reference Fig.12 ,like Fig.10 As shown in FIG. 1 , the number of vertical virtual boundaries is 2. The picture within the luminance sample includes two vertical virtual boundaries, and one vertical virtual boundary is at an x-coordinate of 300 and the other vertical virtual boundary is at an x-coordinate of 600. In addition, as Fig.11 As shown, there is one horizontal virtual boundary, and the horizontal virtual boundary is included at the y coordinate 300 in the picture within the luma sample. Therefore, the coordinates at which the vertical virtual boundary and the horizontal virtual boundary cross each other may be (300, 300) and (600, 300). The edgeFlag[x][y] of the vertical virtual boundary and the horizontal virtual boundary in the picture included in the luma sample corresponds to 0, and the loop filter may not be applied to the corresponding coordinates.

[0305] Fig.13 is a diagram illustrating a method of signaling evenly spaced virtual boundaries according to an embodiment of the present invention.

[0306] Reference Fig.13 , when the value of information indicating whether filtering is performed on a virtual boundary (eg, pps_loop_filter_across_virtual_boundaries_disabled_flag) in the PPS is 1, information showing the number of vertical virtual boundaries (eg, pps_num_ver_virtual_boundaries) may be signaled.

[0307] For example, this information may have a value from 0 to 3.

[0308] In addition, for example, when the information is 1, it may indicate that a vertical virtual boundary exists in the picture.

[0309] In addition, when the value of information indicating whether filtering is performed on a virtual boundary (eg, pps_loop_filter_across_virtual_boundaries_disabled_flag) in the PPS is 1, information showing the number of horizontal virtual boundaries (eg, pps_num_hor_virtual_boundaries) may be signaled.

[0310] For example, this information may have a value from 0 to 3.

[0311] In addition, for example, when the information is 1, it may indicate that a horizontal virtual boundary exists in the picture.

[0312] An example of the derivation of ppsVirtualBoundariesPosX[i] can be described as follows.

[0313] for (i=0; i <pps_num_ver_virtual_boundaries;i++){ ppsVirtualBoundariesPosX[i]=(i+1)×(pic_width_in_luma_sample / (pps_num_ver_virtual_boundaries+1)) } An example of the derivation of ppsVirtualBoundariesPosY[i] can be described as follows.

[0314] for (i=0; i <pps_num_hor_virtual_boundaries;i++){ ppsVirtualBoundariesPosY[i]=(i+1)×(pic_height_in_luma_sample / (pps_num_hor_virtual_boundaries+1)) } Hereinafter, a virtual boundary signaling method using a predetermined offset will be described.

[0315] Fig.14 is a diagram illustrating a method of signaling a virtual boundary through an offset according to an embodiment of the present invention.

[0316] The position information of the virtual boundary may include at least one of first position information for a vertical virtual boundary and second position information for a horizontal virtual boundary.

[0317] Here, the first position information may be determined based on at least one of: width information of the image unit, the number of vertical virtual boundaries belonging to the image unit, and a predetermined first offset.

[0318] Here, the first offset may mean a horizontal offset.

[0319] For example, the first offset may be specified as a distance from the left or right border of the screen to the current virtual border.

[0320] Additionally, for example, the first offset may be specified as a distance from a previous vertical virtual boundary within the screen to a current virtual boundary.

[0321] Here, the second position information may be determined based on at least one of height information of the image unit, information on the number of horizontal virtual boundaries belonging to the image unit, and a predetermined second offset.

[0322] Here, the second offset may represent a vertical offset.

[0323] For example, the second offset may be specified as the distance from the top or bottom border of the screen to the current virtual border.

[0324] Additionally, for example, the second offset may be specified as a distance from a previous horizontal virtual boundary within the screen to a current virtual boundary.

[0325] In addition, the above-mentioned image units may represent pictures, slices, parallel blocks, sub-parallel blocks or sub-pictures. Width information, information about the number, and all or some offsets may be signaled in the encoder or derived in the decoder. Here, the derivation may be performed based on coding parameters signaled in the encoder or based on values ​​predefined in the decoder. Here, the coding parameters may include the following information: the width / height of the picture, the shape of the slice, whether the picture is divided into parallel blocks or sub-parallel blocks / sub-pictures, the number of parallel blocks or sub-parallel blocks, the number of sub-pictures, and the size of the coding tree block (CTB).

[0326] Hereinafter, a method of specifying a distance from a left or right boundary / top or bottom boundary of a screen to a current virtual boundary will be described.

[0327] When a value of information indicating whether filtering is performed on a virtual boundary (eg, pps_loop_filter_across_virtual_boundaries_disabled_flag) in the PPS is 1, the following information may be signaled.

[0328] For example, information indicating the number of vertical virtual boundaries (eg, pps_num_ver_virtual_boundaries) may be signaled.

[0329] Here, the information may have a value from 1 to 3.

[0330] In addition, for example, information indicating the left (or right) boundary of the picture (eg, pps_virtual_boundary_x) may be signaled.

[0331] Furthermore, for example, information specifying the vertical positions for i virtual boundaries may be signaled (eg, pps_virtual_boundries_pos_x_offset[i]).

[0332] Here, the information may have a value from 1 to Ceil(pic_width_in_luma_sample / 8)-1.

[0333] In addition, for example, information indicating the number of horizontal virtual boundaries (eg, pps_num_hor_virtual_boundaries) may be signaled.

[0334] Here, the information may have a value from 1 to 3.

[0335] In addition, for example, information indicating the top (or bottom) boundary of the picture (eg, pps_virtual_boundary_y) may be signaled.

[0336] Furthermore, for example, information specifying the horizontal positions for i virtual boundaries may be signaled (eg, pps_virtual_boundaries_pos_y_offset[i]).

[0337] Here, the information may have a value from 1 to Ceil(pic_height_in_luma_sample / 8)-1.

[0338] An example of the derivation and constraints of ppsVirtualBoundariesPosX[i] can be described as follows.

[0339] ppsVirtualBoundariesPosX[0]=pps_virtual_boundary_x×8; ppsVirtualBoundariesPosX[i]=ppsVirtualBoundariesPosX[0]+(pps_virtual_boundries_pos_x_offset[i] ×8) Constraint: The minimum offset of the distance between two vertical virtual boundaries should be equal to or greater than CtbSizeY.

[0340] An example of the derivation and constraints of ppsVirtualBoundariesPosY[i] can be described as follows.

[0341] ppsVirtualBoundaryPosY[0]=pps_virtual_boundary_y×8; ppsVirtualBoundariesPosY[i]=ppsVirtualBoundariesPosY[0]+(pps_virtual_boundries_pos_y_offset[i] ×8) Constraint: The minimum offset of the distance between two horizontal virtual borders should be equal to or greater than CtbSizeY.

[0342] Hereinafter, a method of specifying a distance from a previous vertical / horizontal virtual boundary within a screen to a current virtual boundary will be described.

[0343] When a value of information indicating whether filtering is performed on a virtual boundary (eg, pps_loop_filter_across_virtual_boundaries_disabled_flag) in the PPS is 1, the following information may be signaled.

[0344] For example, information indicating the number of vertical virtual boundaries (eg, pps_num_ver_virtual_boundaries) may be signaled.

[0345] Here, the information may have a value from 0 to 3.

[0346] Furthermore, for example, information specifying the vertical positions for i virtual boundaries may be signaled (eg, pps_virtual_boundries_pos_x_offset[i]).

[0347] Here, the information may have a value from 1 to Ceil(pic_width_in_luma_sample / 8)-1.

[0348] In addition, for example, information indicating the number of horizontal virtual boundaries (eg, pps_num_hor_virtual_boundaries) may be signaled.

[0349] Here, the information may have a value from 0 to 3.

[0350] Furthermore, for example, information specifying the horizontal positions for i virtual boundaries may be signaled (eg, pps_virtual_boundaries_pos_y_offset[i]).

[0351] Here, the information may have a value from 1 to Ceil(pic_height_in_luma_sample / 8)-1.

[0352] An example of the derivation and constraints of ppsVirtualBoundariesPosX[i] can be described as follows.

[0353] ppsVirtualBoundariesPosX[0]=pps_virtual_boundary_x×8; ppsVirtualBoundariesPosX[i+1]=ppsVirtualBoundariesPosX[i]+(pps_virtual_boundries_pos_x_offset[i] ×8); Constraint: The minimum offset of the distance between two vertical virtual boundaries should be equal to or greater than CtbSizeY.

[0354] An example of the derivation and constraints of ppsVirtualBoundariesPosY[i] can be described as follows.

[0355] ppsVirtualBoundaryPosY[0]=pps_virtual_boundary_y×8; ppsVirtualBoundariesPosY[i+1]=ppsVirtualBoundariesPosX[i]+(pps_virtual_boundries_pos_y_offset[i] ×8); Constraint: The minimum offset of the distance between two horizontal virtual borders should be equal to or greater than CtbSizeY.

[0356] Hereinafter, a virtual boundary signaling method using an absolute value offset will be described.

[0357] Fig.15 is a diagram illustrating a method of signaling a virtual boundary through an absolute value offset according to an embodiment of the present invention.

[0358] When a value of information indicating whether filtering is performed on a virtual boundary (eg, pps_loop_filter_across_virtual_boundaries_disabled_flag) in the PPS is 1, the following information may be signaled.

[0359] For example, information indicating the number of vertical virtual boundaries (eg, pps_num_ver_virtual_boundaries) may be signaled.

[0360] Here, the information may have a value from 0 to 3.

[0361] In information indicating the sign of the vertical position coordinate for the virtual boundary (eg, pps_virtual_boundaries_pos_x_sign[i]), the sign of the absolute value of x_abs_offset for the i-th boundary may be specified.

[0362] Furthermore, in information indicating an absolute value of an offset specifying a vertical position for a virtual boundary (eg, pps_virtual_boundaries_pos_x_abs_offset[i]), a vertical position for an i-th boundary may be specified.

[0363] Here, the information may have a value from 1 to Ceil(pic_width_in_luma_sample / 8)-1.

[0364] For example, information indicating the number of horizontal virtual boundaries (eg, pps_num_hor_virtual_boundaries) may be signaled.

[0365] Here, the information may have a value from 0 to 3.

[0366] In the information indicating the sign of the horizontal position coordinates for the virtual boundary (eg, pps_virtual_boundaries_pos_y_sign[i]), the sign of the absolute value of y_abs_offset for the i-th boundary may be specified.

[0367] Also, in information indicating an absolute value of an offset specifying a horizontal position for a virtual boundary (eg, pps_virtual_boundaries_pos_y_abs_offset[i]), a horizontal position for an i-th boundary may be specified.

[0368] Here, the information may have a value from 1 to Ceil(pic_height_in_luma_sample / 8)-1.

[0369] An example of the derivation and constraints of ppsVirtualBoundariesPosX[i] can be described as follows.

[0370] ppsVirtualBoundariesPosX[0]=pps_virtual_boundary_x×8; pos_x_delta=pps_vitural_boundaries_pos_x_sign[i]? pps_virtual_boundries_pos_x_offset[i]:0-pps_virtual_boundries_pos_x_offset[i]; ppsVirtualBoundariesPosX[i+1]=ppsVirtualBoundariesPosX[i]+(pos_x_delta×8); Constraint: The minimum offset of the distance between two vertical virtual boundaries should be equal to or greater than CtbSizeY.

[0371] Additionally, an example of the derivation and constraints of ppsVirtualBoundariesPosY[i] can be described as follows.

[0372] ppsVirtualBoundaryPosY[0]=pps_virtual_boundary_y×8; pos_y_delta=pps_vitural_boundaries_pos_y_sign[i]? pps_virtual_boundries_pos_y_offset[i]:0-pps_virtual_boundries_pos_y_offset[i]; ppsVirtualBoundariesPosY[i+1]=ppsVirtualBoundariesPosX[i]+(pos_y_delta×8); Constraint: The minimum offset of the distance between two horizontal virtual borders should be equal to or greater than CtbSizeY.

[0373] Hereinafter, a uniformly spaced virtual boundary signaling method using an offset will be described.

[0374] Fig.16 is a diagram illustrating a method of signaling evenly spaced virtual boundaries through offsets according to an embodiment of the present invention.

[0375] Reference Fig.16 , when the value of information indicating whether filtering is performed on virtual boundaries (eg, pps_loop_filter_across_virtual_boundaries_disabled_flag) in the PPS is 1, the following information may be signaled.

[0376] For example, information indicating the number of vertical virtual boundaries (eg, pps_num_ver_virtual_boundaries) may be signaled.

[0377] This information can have a value from 0 to 3.

[0378] For example, when the information is 1, it may indicate that a vertical virtual boundary exists in the picture.

[0379] In addition, for example, information indicating the number of horizontal virtual boundaries (eg, pps_num_hor_virtual_boundaries) may be signaled.

[0380] Here, the information may have a value from 0 to 3.

[0381] For example, when the information is 1, it may indicate that a horizontal virtual boundary exists in the picture.

[0382] In information indicating the sign of the vertical position coordinate for the virtual boundary (eg, pps_virtual_boundaries_pos_x_sign[i]), the sign of the absolute value of x_abs_offset for the i-th boundary may be specified.

[0383] Furthermore, in information indicating an absolute value of an offset specifying a vertical position for a virtual boundary (eg, pps_virtual_boundaries_pos_x_abs_offset[i]), a vertical position for an i-th boundary may be specified.

[0384] Here, the information may have a value from 1 to Ceil(pic_width_in_luma_sample / 8)-1.

[0385] Furthermore, in the information indicating the sign of the horizontal position coordinates for the virtual boundary (eg, pps_virtual_boundaries_pos_y_sign[i]), the sign of the absolute value of y_abs_offset for the i-th boundary may be specified.

[0386] In information indicating an absolute value of an offset specifying a horizontal position for a virtual boundary (eg, pps_virtual_boundaries_pos_y_abs_offset[i]), a horizontal position for an i-th boundary may be specified.

[0387] Here, the information may have a value from 1 to Ceil(pic_height_in_luma_sample / 8)-1.

[0388] An example of the derivation and constraints of ppsVirtualBoundariesPosX[i] can be described as follows.

[0389] for (i=0; i <pps_num_ver_virtual_boundaries;i++){ virtualBoundariesPosX=(i+1)×(pic_width_in_luma_sample / (pps_num_ver_virtual_boundaries+1)); delta_pos_x=pps_vitural_boundaries_pos_x_sign[i]? pps_virtual_boundaries_pos_x_abs_offset[i]:0-pps_virtual_boundaries_pos_x_abs_offset[i]; ppsVirtualBoundariesPosX[i]=virtualBoundariesPosX+(delta_pos_x×8); } Constraint: The minimum offset of the distance between two vertical virtual boundaries should be equal to or greater than CtbSizeY.

[0390] An example of the derivation and constraints of ppsVirtualBoundariesPosY[i] can be described as follows.

[0391] for (i=0; i <pps_num_hor_virtual_boundaries;i++){ virtualBoundariesPosY = (i+1) × (pic_height_in_luma_sample / (pps_num_hor_virtual_boundaries+1)) delta_pos_y=pps_vitural_boundaries_pos_y_sign[i]? pps_virtual_boundaries_pos_y_abs_offset[i]:0-pps_virtual_boundaries_pos_y_abs_offset[i]; ppsVirtualBoundariesPosY[i]=virtualBoundariesPosY+(delta_pos_y×8); } Constraint: The minimum offset of the distance between two horizontal virtual borders should be equal to or greater than CtbSizeY.

[0392] Hereinafter, a virtual boundary signaling method using an offset value will be described.

[0393] Fig.17 is a diagram illustrating a method (Syntax) of signaling information about a virtual boundary through an offset value according to an embodiment of the present invention.

[0394] Reference Fig.17, an initial vertical / horizontal virtual boundary position is signaled, and the remaining virtual boundaries may be calculated based on the offset value and / or number of vertical / horizontal virtual boundaries within the picture.

[0395] Here, information on the position, offset, and number of virtual boundaries may be signaled in a picture header (PH), a PPS, and an SPS.

[0396] Reference Fig.17 , information specifying the vertical position for i virtual boundaries (eg, pps_virtual_boundaries_pos_x_offset[i]) may be used to calculate ppsVirtualBoundariesPosX[i], ie, the position of the i-th vertical virtual boundary in luma sample units.

[0397] Here, the information may have a value from 1 to Ceil(pic_width_in_luma_samples / 8)-1.

[0398] Therefore, an example of deriving ppsVirtualBoundariesPosX[i] (the position of the i-th virtual boundary) can be described as follows.

[0399] When i is 0 (i==0), ppsVirtualBoundariesPosX[i]=pps_virtual_boundaries_pos_x_offset[i]×8 When i is greater than 0 (i>0), ppsVirtualBoundariesPosX[i]=ppsVirtualBoundariesPosX[i-1]+(pps_virtual_boundaries_pos_x_offset[i] ×8) Information specifying the horizontal positions for i virtual boundaries (eg, pps_virtual_boundaries_pos_y_offset[i]) may be used to calculate ppsVirtualBoundariesPosY[i], ie, the position of the i-th virtual boundary in luma sample units.

[0400] Here, the information may have a value from 1 to Ceil(pic_width_in_luma_samples / 8)-1.

[0401] Therefore, an example of deriving ppsVirtualBoundariesPosY[i] (the position of the i-th horizontal virtual boundary) can be described as follows.

[0402] When i is 0 (i==0), ppsVirtualBoundariesPosY[i]=pps_virtual_boundaries_pos_y_offset[i]×8.

[0403] When i is greater than 0 (i>0), ppsVirtualBoundariesPosY[i]=ppsVirtualBoundariesPosY[i-1]+(pps_virtual_boundaries_pos_y_offset[i]×8).

[0404] Hereinafter, a virtual boundary signaling method using uniformly spaced values / offset values ​​will be described.

[0405] Fig.18 is a diagram illustrating a method (syntax) of signaling a virtual boundary through evenly spaced values / offset values ​​according to an embodiment of the present invention.

[0406] For vertical / horizontal virtual border signaling, the same shape using absolute values ​​and offset values ​​(including vertical / horizontal border position values) can be distinguished.

[0407] Here, information about the same shape and offset may be signaled in both the SPS and the PPS.

[0408] Reference Fig.18 , when the value of the information indicating whether the vertical virtual boundaries are uniformly distributed (eg, pps_ver_virtual_boundaries_uniform_spacing_flag) is 1, it indicates that the vertical virtual boundaries of the picture are uniformly distributed.

[0409] For example, information indicating the number of vertical virtual boundaries (eg, pps_num_ver_virtual_boundaries) may be signaled.

[0410] When the value of the information indicating whether the vertical virtual boundaries are uniformly distributed (eg, pps_ver_virtual_boundaries_uniform_spacing_flag) is 0, the vertical virtual boundaries may be non-uniformly distributed.

[0411] For example, information indicating the number of vertical virtual boundaries (eg, pps_num_ver_virtual_boundaries) may be signaled.

[0412] Furthermore, for example, information indicating the vertical positions for i virtual boundaries may be signaled (eg, pps_virtual_boundaries_pos_x[i]).

[0413] When there is no vertical virtual boundary, the value of information indicating whether the vertical virtual boundary is uniformly distributed (eg, pps_ver_virtual_boundaries_uniform_spacing_flag) may be inferred to be 0.

[0414] Therefore, an example of the derivation of ppsVirtualBoundariesPosX[i] can be described as follows.

[0415] When the value of the information indicating whether the vertical virtual boundaries are uniformly distributed (for example, pps_ver_virtual_boundaries_uniform_spacing_flag) is 1, for (i=0; i <pps_num_ver_virtual_boundaries;i++){ ppsVirtualBoundariesPosX[i]=(i+1)×(pic_width_in_luma_sample / (pps_num_ver_virtual_boundaries+1)) } When the value of the information indicating whether the vertical virtual boundaries are uniformly distributed (for example, pps_ver_virtual_boundaries_uniform_spacing_flag) is not 1, ppsVirtualBoundariesPosX[i]=pps_virtual_boundaries_pos_x[i]×8 When the value of the information indicating whether the horizontal virtual boundaries are uniformly distributed (eg, pps_hor_virtual_boundaries_uniform_spacing_flag) is 1, it means that the horizontal virtual boundaries of the picture are uniformly distributed.

[0416] For example, information indicating the number of horizontal virtual boundaries (eg, pps_num_hor_virtual_boundaries) may be signaled.

[0417] When the value of the information indicating whether the horizontal virtual boundaries are uniformly distributed (eg, pps_hor_virtual_boundaries_uniform_spacing_flag) is 0, the horizontal virtual boundaries may be non-uniformly distributed.

[0418] For example, information indicating the number of horizontal virtual boundaries (eg, pps_num_hor_virtual_boundaries) may be signaled. For example, information indicating the horizontal positions for i virtual boundaries (eg, pps_virtual_boundaries_pos_y[i]) may be signaled.

[0419] When there is no horizontal virtual boundary, the value of information indicating whether the horizontal virtual boundary is uniformly distributed (eg, pps_hor_virtual_boundaries_uniform_spacing_flag) may be inferred to be 0.

[0420] Therefore, an example of the derivation of ppsVirtualBoundariesPosY[i] can be described as follows.

[0421] When the value of the information indicating whether the horizontal virtual boundaries are uniformly distributed (for example, pps_hor_virtual_boundaries_uniform_spacing_flag) is 1, for (i=0; i <pps_num_hor_virtual_boundaries;i++){ ppsVirtualBoundariesPosY[i]=(i+1)×(pic_height_in_luma_sample / (pps_num_hor_virtual_boundaries+1)) } When the value of the information indicating whether the horizontal virtual boundaries are uniformly distributed (for example, pps_hor_virtual_boundaries_uniform_spacing_flag) is not 1, ppsVirtualBoundariesPosY[i]=pps_virtual_boundaries_pos_y[i]×8 The above-described embodiments may be performed in the same manner in an encoder and a decoder.

[0422] At least one embodiment or a combination of the above embodiments may be used to encode / decode a video.

[0423] The order in which the above-described embodiments are applied may be different between an encoder and a decoder, or the order in which the above-described embodiments are applied may be the same in an encoder and a decoder.

[0424] The above-described embodiments may be performed on each luminance signal and each chrominance signal, or may be performed identically on the luminance signal and the chrominance signal.

[0425] The block form to which the above-described embodiment of the present invention is applied may have a square form or a non-square form.

[0426] At least one of the syntax elements (flags, indices, etc.) entropy encoded in the encoder and the syntax elements (flags, indices, etc.) entropy decoded in the decoder may use at least one of the following binarization, debinarization, entropy encoding / decoding methods.

[0427] - Binarization / debinarization method of signed 0th order Exp_Golomb (se(v)) - Signed k-order Exp_Golomb binarization / debinarization method (sek(v)) - Binarization / debinarization method of Exp_Golomb of order 0 for unsigned positive integers (ue(v)) - Unsigned positive integer k-th order Exp_Golomb binarization / debinarization method (uek(v)) -Fixed length binarization / debinarization method (f(n)) - Truncated Rice binarization / debinarization method or truncated unary binarization / debinarization method (tu(v)) - Truncated Binary Binarization / Debinarization Method (tb(v)) -Context-adaptive arithmetic coding / decoding method (ae(v)) -Byte unit bit string (b(8)) - Binarization / debinarization methods for signed integers (i(n)) - Binarization / debinarization method for unsigned positive integers (u(n)) - Unary Binarization / Debinarization Method The above-mentioned embodiments of the present invention may be applied according to the size of at least one of a coding block, a prediction block, a transform block, a block, a current block, a coding unit, a prediction unit, a transform unit, a unit, and a current unit. Here, the size may be defined as a minimum size or a maximum size or both a minimum size and a maximum size so that the above-mentioned embodiments are applied, or the size may be defined as a fixed size to which the above-mentioned embodiments are applied. In addition, in the above-mentioned embodiments, the first embodiment may be applied to a first size, and the second embodiment may be applied to a second size. In other words, the above-mentioned embodiments may be applied in combination according to the size. In addition, the above-mentioned embodiments may be applied when the size is equal to or greater than the minimum size and equal to or less than the maximum size. In other words, the above-mentioned embodiments may be applied when the block size is included in a specific range.

[0428] For example, when the size of the current block is 8×8 or larger, the above embodiment may be applied. For example, when the size of the current block is only 4×4, the above embodiment may be applied. For example, when the size of the current block is 16×16 or smaller, the above embodiment may be applied. For example, when the size of the current block is equal to or larger than 16×16 and equal to or smaller than 64×64, the above embodiment may be applied.

[0429] The above-described embodiments of the present invention may be applied according to time layers. In order to identify the time layers to which the above-described embodiments may be applied, a corresponding identifier may be signaled, and the above-described embodiments may be applied to the specified time layers identified by the corresponding identifier. Here, the identifier may be defined as the lowest layer or the highest layer or both the lowest layer and the highest layer to which the above-described embodiments may be applied, or may be defined as a specific layer to which the embodiments may be applied. In addition, a fixed time layer to which the embodiments may be applied may be defined.

[0430] For example, when the temporal layer of the current image is the lowest layer, the above embodiment may be applied. For example, when the temporal layer identifier of the current image is 1, the above embodiment may be applied. For example, when the temporal layer of the current image is the highest layer, the above embodiment may be applied.

[0431] A slice type or a tile group type to which the above-described embodiments of the present invention are applied may be defined, and the above-described embodiments may be applied according to the corresponding slice type or tile group type.

[0432] In the above embodiments, the method is described based on a flowchart having a series of steps or units, but the present invention is not limited to the order of the steps, but some steps may be performed simultaneously with other steps or in a different order. In addition, it should be understood by those skilled in the art that the steps in the flowchart are not mutually exclusive, and other steps may be added to the flowchart, or some steps may be deleted from the flowchart without affecting the scope of the present invention.

[0433] The embodiments include various aspects of the examples. All possible combinations for various aspects may not be described, but those skilled in the art will be able to recognize different combinations. Therefore, the present invention may include all substitutions, modifications and changes within the scope of the claims.

[0434] Embodiments of the present invention may be implemented in the form of program instructions that can be executed by various computer components and recorded in a computer-readable recording medium. The computer-readable recording medium may include a separate program instruction, a data file, a data structure, etc., or a combination of program instructions, data files, data structures, etc. The program instructions recorded in the computer-readable recording medium may be specially designed and constructed for the present invention, or known to ordinary technicians in the field of computer software technology. Examples of computer-readable recording media include magnetic recording media (such as hard disks, floppy disks, and tapes), optical data storage media (such as CD-ROMs or DVD-ROMs), magneto-optical media (such as floppy disks), and hardware devices (such as read-only memory (ROM), random access memory (RAM), flash memory, etc.) that are specifically constructed to store and implement program instructions. Examples of program instructions include not only machine language codes formatted by a compiler, but also high-level language codes that can be implemented by a computer using an interpreter. The hardware device may be configured to be operated by one or more software modules to perform processing according to the present invention, or vice versa.

[0435] Although the present invention has been described according to specific items such as detailed elements and limited embodiments and drawings, they are provided only to help a greater understanding of the present invention, and the present invention is not limited to the above embodiments. It will be appreciated by those skilled in the art that various modifications and changes can be made from the above description.

[0436] Therefore, the spirit of the present invention should not be limited to the above-described embodiments, and the entire scope of the claims and their equivalents will fall within the scope and spirit of the present invention.

[0437] Industrial Applicability The present invention can be used to encode or decode images.

Claims

1. A video decoding method, the method comprising: decoding a first flag indicating whether information indicating whether a virtual boundary is signaled in a sequence parameter set SPS, the first flag being related to whether an in-loop filtering operation is disabled across a virtual boundary; decoding quantity information regarding the number of virtual boundaries based on the first flag; Based on the first flag, deriving the position of the virtual boundary by selectively using first position information about the position of the virtual boundary signaled in the SPS and second position information about the position of the virtual boundary signaled in the picture header PH, wherein, in response to information indicating a virtual boundary being signaled in the SPS in response to the first flag, the position of the virtual boundary is derived by using first position information about the position of the virtual boundary signaled in the SPS, wherein, in response to the first flag indicating that information of the virtual boundary is not signaled in the SPS, the position of the virtual boundary is derived by using second position information about the position of the virtual boundary signaled in the PH, wherein the position of the virtual boundary is derived based on the first marker by applying a predetermined weight to the first position information or the second position information, Among them, the predetermined weight is 8.

2. The video decoding method according to claim 1, in, In response to information of the first flag indicating the virtual boundary being signaled in the SPS, the quantity information is decoded from the SPS, Wherein, in response to the first flag indicating that information of the virtual boundary is not signaled in the SPS, the quantity information is decoded from the PH.

3. The video decoding method according to claim 1, in, The number of virtual borders means the number of horizontal virtual borders or the number of vertical virtual borders.

4. A video encoding method, the method comprising: encoding the first flag and the number of virtual boundaries in the bit stream, The first flag indicates whether information of the virtual boundary is signaled in a sequence parameter set SPS of the bitstream, and the first flag is related to whether the in-loop filtering operation is disabled across the virtual boundary. wherein, based on whether information of virtual boundaries is encoded in the SPS, quantity information about the number of virtual boundaries is encoded, Wherein, based on whether the information of the virtual boundary is encoded in the SPS, the first position information about the position of the virtual boundary encoded in the SPS or the second position information about the position of the virtual boundary encoded in the picture header PH is encoded, wherein, in response to the information of the virtual boundary being determined to be encoded in the SPS, the first position information is determined based on the position of the virtual boundary and encoded in the SPS, wherein, in response to the information of the virtual boundary being determined not to be encoded in the SPS, the second position information is determined based on the position of the virtual boundary and encoded in the PH, wherein the position of the virtual boundary is derived based on the first marker by applying a predetermined weight to the first position information or the second position information, Among them, the predetermined weight is 8.

5. The video encoding method according to claim 4, in, In response to the virtual boundary information being determined to be encoded in the SPS, the quantity information is encoded in the SPS, In which, in response to the information of the virtual boundary being determined not to be encoded in the SPS, the quantity information is encoded in the PH.

6. The video encoding method according to claim 4, in, The number of virtual borders means the number of horizontal virtual borders or the number of vertical virtual borders.

7. A method for sending a bit stream, comprising: encoding the first flag and the number of virtual boundaries in a bit stream; as well as Send bitstream, The first flag indicates whether information of the virtual boundary is signaled in a sequence parameter set SPS of the bitstream, and the first flag is related to whether the in-loop filtering operation is disabled across the virtual boundary. wherein, based on whether information of virtual boundaries is encoded in the SPS, quantity information about the number of virtual boundaries is encoded, Wherein, based on whether the information of the virtual boundary is encoded in the SPS, the first position information about the position of the virtual boundary encoded in the SPS or the second position information about the position of the virtual boundary encoded in the picture header PH is encoded, wherein, in response to the information of the virtual boundary being determined to be encoded in the SPS, the first position information is determined based on the position of the virtual boundary and encoded in the SPS, wherein, in response to the information of the virtual boundary being determined not to be encoded in the SPS, the second position information is determined based on the position of the virtual boundary and encoded in the PH, wherein the position of the virtual boundary is derived based on the first marker by applying a predetermined weight to the first position information or the second position information, Among them, the predetermined weight is 8.

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