Method and device for video decoding, and method and device for video encoding

Abstract

The present invention proposes a method and device for decoding a video, the method comprising: in a video encoding and decoding procedure, determining whether a current block is in contact with an upper boundary of a maximum encoding unit including the current block; if it is determined that the current block is in contact with the upper boundary of the maximum encoding unit, determining an upper reference line of the current block as one reference line; and if it is determined that the current block is not in contact with the upper boundary of the maximum encoding unit, determining the upper reference line of the current block on the basis of N reference lines, and using the determined upper reference line.

Description

Video decoding method and device, video encoding method and device

[0001] The present disclosure relates to a video decoding method and a video decoding device, and more specifically, to a method and device for encoding a video, and a decoding method and device, which determine and use an upper reference line as one reference line when a current block touches an upper boundary line of a maximum encoding unit including the current block when using at least one reference line.

[0002] Video data is encoded using a codec according to a given data compression standard, such as the MPEG (Moving Picture Expert Group) standard, and then stored on a recording medium in the form of a bitstream or transmitted through a communication channel.

[0003] With the development and widespread adoption of hardware capable of playing and storing high-resolution or high-definition video content, the need for codecs that effectively encode or decode such content is increasing. Encoded video content can be played back by decoding it. Recently, methods for effectively compressing such high-resolution or high-definition video content have been developed. For example, video compression techniques have been proposed to effectively implement video compression by arbitrarily segmenting the video to be encoded or manipulating the data.

[0004] As one of the techniques for manipulating data, it is common to use one or two reference lines to make predictions.

[0005] During a video encoding and decoding process, a method and device are proposed for determining whether a current block touches an upper boundary of a maximum encoding unit including the current block, and if it touches the upper boundary, determining an upper reference line of the current block as one reference line, and if it does not touch the upper boundary, determining an upper reference line of the current block based on N reference lines, and using the determined upper reference line.

[0006] In order to solve the above technical problem, the video decoding method proposed in the present disclosure includes the steps of: determining whether a current block touches an upper boundary line of a maximum coding unit including the current block; determining an upper reference line of the current block as one reference line if it is determined that the current block touches the upper boundary line of the maximum coding unit; determining an upper reference line of the current block based on N reference lines if it is determined that the current block does not touch the upper boundary line of the maximum coding unit; and performing a prediction on the current block based on the determined upper reference line, wherein N may be a natural number.

[0007] In order to solve the above technical problem, the video decoding device proposed in the present disclosure comprises: a memory; and at least one processor connected to the memory, wherein the at least one processor is configured to: determine whether a current block touches an upper boundary of a maximum coding unit including the current block, and if it is determined that the current block touches the upper boundary of the maximum coding unit, determine an upper reference line of the current block as one reference line, and if it is determined that the current block does not touch the upper boundary of the maximum coding unit, determine an upper reference line of the current block based on N reference lines, and perform prediction on the current block based on the determined upper reference line, where N may be a natural number.

[0008] In order to solve the above technical problem, the video encoding method proposed in the present disclosure includes the steps of: determining whether a current block touches an upper boundary line of a maximum coding unit including the current block; determining an upper reference line of the current block as one reference line if it is determined that the current block touches the upper boundary line of the maximum coding unit; determining an upper reference line of the current block based on N reference lines if it is determined that the current block does not touch the upper boundary line of the maximum coding unit; and performing a prediction on the current block based on the determined upper reference line, wherein N may be a natural number.

[0009] In order to solve the above technical problem, the video encoding device proposed in the present disclosure includes at least one processor connected to the memory, and the at least one processor is configured to: determine whether a current block touches an upper boundary line of a maximum coding unit including the current block, and if it is determined that the current block touches the upper boundary line of the maximum coding unit, determine an upper reference line of the current block as one reference line, and if it is determined that the current block does not touch the upper boundary line of the maximum coding unit, determine an upper reference line of the current block based on N reference lines, and perform prediction on the current block based on the determined upper reference line, where N may be a natural number.

[0010] During a video encoding and decoding process, it is determined whether a current block touches an upper boundary of a maximum encoding unit that includes the current block, and if it is determined to touch the upper boundary, an upper reference line of the current block is determined as one reference line, and if it is determined not to touch the upper boundary, an upper reference line of the current block is determined based on N reference lines, and by using the determined upper reference line, the amount of buffer generated when using multiple reference lines can be reduced.

[0011] FIG. 1 illustrates a schematic block diagram of an image decoding device according to one embodiment.

[0012] FIG. 2 illustrates a flowchart of an image decoding method according to one embodiment.

[0013] FIG. 3 illustrates a process in which an image decoding device divides a current encoding unit to determine at least one encoding unit according to one embodiment.

[0014] FIG. 4 illustrates a process in which an image decoding device determines at least one encoding unit by dividing a non-square encoding unit according to one embodiment.

[0015] FIG. 5 illustrates a process in which an image decoding device divides an encoding unit based on at least one of block shape information and division shape mode information, according to one embodiment.

[0016] FIG. 6 illustrates a method for a video decoding device to determine a predetermined encoding unit among an odd number of encoding units according to one embodiment.

[0017] FIG. 7 illustrates the order in which multiple encoding units are processed when an image decoding device determines multiple encoding units by dividing a current encoding unit according to one embodiment.

[0018] FIG. 8 illustrates a process for determining that a current encoding unit is divided into an odd number of encoding units when the encoding units cannot be processed in a predetermined order, according to one embodiment.

[0019] FIG. 9 illustrates a process in which an image decoding device divides a first encoding unit to determine at least one encoding unit according to one embodiment.

[0020] FIG. 10 illustrates that, according to one embodiment, a video decoding device limits the shapes into which a second encoding unit can be divided when a non-square shape of a second encoding unit determined by dividing a first encoding unit satisfies a predetermined condition.

[0021] FIG. 11 illustrates a process of a video decoding device dividing a square-shaped encoding unit when the split shape mode information cannot indicate that the encoding unit is divided into four square-shaped encoding units according to one embodiment.

[0022] FIG. 12 illustrates that, according to one embodiment, the processing order between multiple encoding units may vary depending on the process of dividing the encoding units.

[0023] FIG. 13 illustrates a process in which the depth of an encoding unit is determined as the shape and size of the encoding unit change when the encoding unit is recursively divided to determine a plurality of encoding units according to one embodiment.

[0024] FIG. 14 illustrates an index (part index, hereinafter referred to as PID) for depth and encoding unit distinction that can be determined according to the shape and size of encoding units according to one embodiment.

[0025] FIG. 15 illustrates that a plurality of encoding units are determined according to a plurality of predetermined data units included in a picture according to one embodiment.

[0026] FIG. 16 illustrates a processing block that serves as a criterion for determining the order of determination of reference coding units included in a picture according to one embodiment.

[0027] FIG. 17 illustrates a block diagram of a video encoding device according to one embodiment.

[0028] FIG. 18 illustrates a flowchart of a video encoding method according to one embodiment.

[0029] FIG. 19 illustrates a block diagram of a video decoding device according to one embodiment.

[0030] FIG. 20 illustrates a flowchart of a video decoding method according to one embodiment.

[0031] FIG. 21 is a drawing for explaining a method of using at least one reference line according to one embodiment.

[0032] FIG. 22 illustrates a flowchart of a video encoding method according to another embodiment.

[0033] FIG. 23 illustrates a flowchart of a video decoding method according to another embodiment.

[0034] FIG. 24a illustrates luma samples located around a current luma block and chroma samples located around a current chroma block according to one embodiment, and FIG. 24b illustrates luma samples of a current luma block and chroma samples of a current chroma block according to one embodiment.

[0035] FIG. 25a illustrates luma samples located around a current luma block and chroma samples located around a current chroma block according to another embodiment, and FIG. 25b illustrates luma samples of a current luma block and chroma samples of a current chroma block according to another embodiment.

[0036] FIG. 26a illustrates an embodiment in which the number of upper reference lines and left reference lines is different, FIG. 26b illustrates an embodiment in which the number of upper reference lines and left reference lines is the same, and FIG. 26c illustrates an embodiment in which the number of upper reference lines and left reference lines is different, and the two reference lines are padded to be the same.

[0037] A video decoding method according to an embodiment proposed in the present disclosure includes the steps of: determining whether a current block touches an upper boundary line of a maximum coding unit including the current block; determining an upper reference line of the current block as one reference line if it is determined that the current block touches the upper boundary line of the maximum coding unit; determining an upper reference line of the current block based on N reference lines if it is determined that the current block does not touch the upper boundary line of the maximum coding unit; and performing a prediction on the current block based on the determined upper reference line, wherein N may be a natural number.

[0038] In one embodiment, the N may be determined by reference line information obtained from the bitstream.

[0039] According to one embodiment, if it is determined that the current block touches the upper boundary line of the maximum encoding unit, the reference line information may not be acquired.

[0040] In one embodiment, if N is 2, the upper reference line may be determined as a second reference line that is adjacent to the upper side of a first reference line that is adjacent to the upper side of the current block.

[0041] In one embodiment, if N is 3, the upper reference line may be determined as a fourth reference line that is adjacent to the upper side of a third reference line that is adjacent to the upper side of a second reference line that is adjacent to the upper side of a first reference line that is adjacent to the upper side of the current block.

[0042] In one embodiment, the left reference line located to the left of the current block may be determined based on N reference lines.

[0043] In one embodiment, if there is a reference line without a sample value in the upper reference line, the sample values ​​of the reference line without a sample value may be padded using a predetermined default value.

[0044] In one embodiment, if there is a reference line without a sample value in the upper reference line, the reference sample value having a sample value may be padded with the reference sample without a sample value, or if there is a reference line without a sample value in the upper reference line, the sample of the reference line without a sample value may be regenerated using the sample value of the reference line with a sample value.

[0045] A video decoding method according to an embodiment proposed in the present disclosure may include: a step of determining whether a current luma block touches an upper boundary of a maximum coding unit including the current luma block; a step of determining an upper reference line of the current luma block as one reference line if it is determined that the current luma block touches the upper boundary of the maximum coding unit; a step of determining an upper reference line of the current luma block as two reference lines if it is determined that the current luma block does not touch the upper boundary of the maximum coding unit; and a step of performing a prediction on a current chroma block corresponding to the current luma block based on the determined upper reference line.

[0046] In one embodiment, the two reference lines may include a first reference line tangent to an upper side of the current luma block and a second reference line tangent to an upper side of the first reference line.

[0047] According to one embodiment, weight information and deviation information are determined using a relationship between luma reference samples of the current luma block included in the upper reference line and chroma reference samples bordering the upper side of the current chroma block, and prediction for the current chroma block can be performed by determining the current chroma block based on the weight information, the deviation information, and the luma samples of the current luma block.

[0048] A video encoding method according to an embodiment proposed in the present disclosure comprises the steps of: determining whether a current block touches an upper boundary line of a maximum coding unit including the current block; determining an upper reference line of the current block as one reference line if it is determined that the current block touches the upper boundary line of the maximum coding unit; determining an upper reference line of the current block based on N reference lines if it is determined that the current block does not touch the upper boundary line of the maximum coding unit; and performing a prediction on the current block based on the determined upper reference line, wherein N may be a natural number.

[0049] According to one embodiment, the method may include generating reference line information representing the value of N.

[0050] According to one embodiment, if it is determined that the current block touches the upper boundary line of the maximum encoding unit, the reference line information may not be generated.

[0051] In one embodiment, when N is 3, the upper reference line may be determined as a fourth reference line that is adjacent to the upper side of a third reference line that is adjacent to the upper side of a second reference line that is adjacent to the upper side of a first reference line that is adjacent to the upper side of the current block.

[0052] The advantages and features of the disclosed embodiments, and the methods for achieving them, will become clearer with reference to the embodiments described below, along with the accompanying drawings. However, the present disclosure is not limited to the embodiments disclosed below and may be implemented in various different forms. These embodiments are provided solely to ensure the completeness of the disclosure and to fully inform those skilled in the art of the present disclosure of the scope of the invention.

[0053] The terms used in this specification will be briefly explained, and the disclosed embodiments will be described in detail.

[0054] The terms used in this specification have been selected from widely used, current terms, taking into account the functions of the present disclosure. However, these terms may vary depending on the intentions of engineers working in the relevant fields, precedents, the emergence of new technologies, etc. Furthermore, in certain cases, terms may be arbitrarily selected by the applicant, and in such cases, their meanings will be described in detail in the relevant description of the invention. Therefore, the terms used in this disclosure should not be defined simply as names, but rather based on the meanings of the terms and the overall content of the present disclosure.

[0055] In this specification, singular expressions include plural expressions unless the context clearly specifies that they are singular.

[0056] When a part of a specification is said to "include" a component, this does not mean that it excludes other components, but rather that it may include other components, unless otherwise stated.

[0057] Also, the term "part" used in the specification means a software or hardware component, and the "part" performs certain functions. However, the "part" is not limited to software or hardware. The "part" may be configured to reside on an addressable storage medium and may be configured to execute one or more processors. Thus, by way of example, the "part" includes components such as software components, object-oriented software components, class components, and task components, as well as processes, functions, attributes, procedures, subroutines, segments of program code, drivers, firmware, microcode, circuits, data, databases, data structures, tables, arrays, and variables. The functionality provided within the components and "parts" may be combined into a smaller number of components and "parts" or further separated into additional components and "parts."

[0058] According to one embodiment of the present disclosure, a "unit" may be implemented as a processor and a memory. The term "processor" should be broadly interpreted to include a general-purpose processor, a central processing unit (CPU), a microprocessor, a digital signal processor (DSP), a controller, a microcontroller, a state machine, and the like. In some circumstances, a "processor" may also refer to an application-specific integrated circuit (ASIC), a programmable logic device (PLD), a field-programmable gate array (FPGA), and the like. The term "processor" may also refer to a combination of processing devices, such as, for example, a combination of a DSP and a microprocessor, a combination of a plurality of microprocessors, a combination of one or more microprocessors in conjunction with a DSP core, or any other such configuration.

[0059] The term "memory" should be interpreted broadly to include any electronic component capable of storing electronic information. The term memory may also refer to various types of processor-readable media, such as random access memory (RAM), read-only memory (ROM), non-volatile random access memory (NVRAM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable PROM (EEPROM), flash memory, magnetic or optical data storage, registers, etc. Memory is said to be in electronic communication with the processor if the processor can read information from the memory and / or write information to the memory. Memory integrated in a processor is in electronic communication with the processor.

[0060] Hereinafter, “image” may refer to a static image such as a still image of a video, or a dynamic image such as a moving image, i.e., the video itself.

[0061] Hereinafter, "sample" refers to data assigned to a sampling location in an image and is the subject of processing. For example, pixel values ​​in a spatial domain image or transformation coefficients in a transformation domain may be samples. A unit containing at least one such sample may be defined as a block.

[0062] Additionally, in this specification, 'current block' may mean a block of the maximum encoding unit, encoding unit, prediction unit, or transformation unit of the current image to be encoded or decoded.

[0063] Below, with reference to the attached drawings, embodiments are described in detail so that those skilled in the art can easily implement the present disclosure. Furthermore, in order to clearly illustrate the present disclosure in the drawings, parts irrelevant to the description are omitted.

[0064] Referring to FIGS. 1 to 16 below, an image encoding device and an image decoding device, an image encoding method, and an image decoding method according to one embodiment are described in detail. With reference to FIGS. 3 to 16, a method for determining a data unit of an image according to an embodiment is described, and with reference to FIGS. 17 to 21, a video encoding / decoding method is described below, which determines whether a current block touches an upper boundary of a maximum coding unit including the current block, and if it is determined that the current block touches the upper boundary, an upper reference line of the current block is determined as one reference line, and if it is determined that the current block does not touch the upper boundary, an upper reference line of the current block is determined based on N reference lines, and performs prediction for the current block based on the determined upper reference line, and with reference to FIGS. 22 to 25, a method for determining whether a current luma block touches an upper boundary of a maximum coding unit including the current luma block, and if it is determined that the current luma block touches the upper boundary, an upper reference line of the current luma block is determined as one reference line, and if it is determined that the current luma block does not touch the upper boundary, a method for performing prediction for the current block based on the determined upper reference line is described. A video encoding / decoding method is described below, which determines an upper reference line as two reference lines and performs prediction for a current chroma block corresponding to a current luma block based on the determined upper reference line, and a video encoding / decoding method using a plurality of reference lines according to an embodiment is described below with reference to FIG. 26.

[0065] Hereinafter, with reference to FIGS. 1 and 2, a method and apparatus for adaptively selecting a context model based on various types of encoding units according to one embodiment of the present disclosure are described.

[0066] FIG. 1 illustrates a schematic block diagram of an image decoding device according to one embodiment.

[0067] The video decoding device (100) may include a receiving unit (110) and a decoding unit (120). The receiving unit (110) and the decoding unit (120) may include at least one processor. In addition, the receiving unit (110) and the decoding unit (120) may include a memory that stores instructions to be executed by at least one processor.

[0068] The receiving unit (110) can receive a bitstream. The bitstream includes information obtained by encoding an image by an image encoding device (2200) described below. In addition, the bitstream can be transmitted from the image encoding device (2200). The image encoding device (2200) and the image decoding device (100) can be connected by wire or wirelessly, and the receiving unit (110) can receive the bitstream by wire or wirelessly. The receiving unit (110) can receive the bitstream from a storage medium such as an optical medium or a hard disk. The decoding unit (120) can restore the image based on information obtained from the received bitstream. The decoding unit (120) can obtain syntax elements for restoring the image from the bitstream. The decoding unit (120) can restore the image based on the syntax elements.

[0069] The operation of the video decoding device (100) will be described in more detail with reference to FIG. 2.

[0070] FIG. 2 illustrates a flowchart of an image decoding method according to one embodiment.

[0071] According to one embodiment of the present disclosure, the receiving unit (110) receives a bitstream.

[0072] The image decoding device (100) performs a step (210) of obtaining a binstring corresponding to a splitting shape mode of an encoding unit from a bitstream. The image decoding device (100) performs a step (220) of determining a splitting rule of the encoding unit. In addition, the image decoding device (100) performs a step (230) of splitting the encoding unit into a plurality of encoding units based on at least one of the binstring corresponding to the splitting shape mode and the splitting rule. In order to determine the splitting rule, the image decoding device (100) may determine a first allowable range of the size of the encoding unit according to a ratio of the width and height of the encoding unit. In order to determine the splitting rule, the image decoding device (100) may determine a second allowable range of the size of the encoding unit according to the splitting shape mode of the encoding unit.

[0073] Below, the division of encoding units according to one embodiment of the present disclosure is described in detail.

[0074] First, a picture can be divided into one or more slices or one or more tiles. A slice or a tile can be a sequence of one or more Coding Tree Units (CTUs). The concept that contrasts with a Coding Tree Block (CTB) is a Coding Tree Block (CTB).

[0075] A maximum coding block (CTB) is an NxN block containing NxN samples (where N is an integer). Each color component can be divided into one or more maximum coding blocks.

[0076] When a picture has three sample arrays (sample arrays for Y, Cr, and Cb components), a maximum coding unit (CTU) is a unit that includes a maximum coding block of luma samples, two maximum coding blocks of corresponding chroma samples, and syntax structures used to encode the luma samples and chroma samples. When a picture is a monochrome picture, a maximum coding unit is a unit that includes a maximum coding block of monochrome samples and syntax structures used to encode the monochrome samples. When a picture is a picture that is encoded with a color plane that is separated by color components, a maximum coding unit is a unit that includes syntax structures used to encode the picture and samples of the picture.

[0077] A single maximum coding block (CTB) can be divided into MxN coding blocks containing MxN samples (M, N are integers).

[0078] When a picture has a sample array for each Y, Cr, and Cb component, a coding unit (CU) is a unit that includes a coding block for a luma sample and two coding blocks for corresponding chroma samples, and syntax structures used to encode the luma sample and the chroma samples. When a picture is a monochrome picture, a coding unit is a unit that includes a coding block for a monochrome sample and syntax structures used to encode the monochrome samples. When a picture is a picture that is encoded with a color plane that is separated by color component, a coding unit is a unit that includes syntax structures used to encode the picture and samples of the picture.

[0079] As explained above, the maximum coding block and the maximum coding unit are distinct concepts, and the coding block and the coding unit are distinct concepts. That is, the (maximum) coding unit refers to a data structure including a (maximum) coding block including the corresponding sample and a syntax structure corresponding to it. However, since a person skilled in the art can understand that the (maximum) coding unit or the (maximum) coding block refers to a block of a predetermined size including a predetermined number of samples, the following specification will refer to the maximum coding block and the maximum coding unit, or the coding block and the coding unit, without distinction unless there are special circumstances.

[0080] An image can be divided into Coding Tree Units (CTUs). The size of the CTUs can be determined based on information obtained from the bitstream. The shape of the CTUs can be a square of equal size, but is not limited thereto.

[0081] For example, information about the maximum size of a luma coding block can be obtained from the bitstream. For example, the maximum size of the luma coding block indicated by the information about the maximum size of the luma coding block can be one of 4x4, 8x8, 16x16, 32x32, 64x64, 128x128, and 256x256.

[0082] For example, information about the maximum size of a luma coding block capable of being split into two and the luma block size difference can be obtained from the bitstream. The information about the luma block size difference can indicate the size difference between a luma maximum coding unit and a maximum luma coding block capable of being split into two. Therefore, by combining the information about the maximum size of a luma coding block capable of being split into two obtained from the bitstream and the information about the luma block size difference, the size of the luma maximum coding unit can be determined. Using the size of the luma maximum coding unit, the size of the chroma maximum coding unit can also be determined. For example, if the Y: Cb: Cr ratio is 4:2:0 according to the color format, the size of the chroma block can be half the size of the luma block, and similarly, the size of the chroma maximum coding unit can be half the size of the luma maximum coding unit.

[0083] According to one embodiment, since information about the maximum size of a luma coding block capable of binary splitting is obtained from a bitstream, the maximum size of the luma coding block capable of binary splitting can be determined variably. Alternatively, the maximum size of a luma coding block capable of ternary splitting can be fixed. For example, the maximum size of a luma coding block capable of ternary splitting in an I picture may be 32x32, and the maximum size of a luma coding block capable of ternary splitting in a P picture or a B picture may be 64x64.

[0084] Additionally, the maximum coding unit can be hierarchically divided into coding units based on the division shape mode information obtained from the bitstream. As the division shape mode information, at least one of information indicating whether quad division is performed, information indicating whether multi-division is performed, division direction information, and division type information can be obtained from the bitstream.

[0085] For example, information indicating whether a quad split is present may indicate whether the current encoding unit is to be quad split (QUAD_SPLIT) or not to be quad split.

[0086] If the current encoding unit is not quad-split, the information indicating whether it is multi-split may indicate whether the current encoding unit will not be split any further (NO_SPLIT) or whether it will be binary / ternary split.

[0087] When the current encoding unit is binary or ternary split, the split direction information indicates that the current encoding unit is split in either the horizontal or vertical direction.

[0088] When the current encoding unit is split in the horizontal or vertical direction, the split type information indicates that the current encoding unit is split into binary split or ternary split.

[0089] Depending on the split direction information and the split type information, the split mode of the current encoding unit can be determined. The split mode when the current encoding unit is split into binaries in the horizontal direction can be determined as binary horizontal split (SPLIT_BT_HOR), the split mode when the current encoding unit is split into ternaries in the horizontal direction can be determined as ternary horizontal split (SPLIT_TT_HOR), the split mode when the current encoding unit is split into binaries in the vertical direction can be determined as binary vertical split (SPLIT_BT_VER), and the split mode when the current encoding unit is split into ternaries in the vertical direction can be determined as ternary vertical split (SPLIT_BT_VER).

[0090] The image decoding device (100) can obtain segmentation shape mode information from a bitstream from a single binstring. The format of the bitstream received by the image decoding device (100) can include a fixed length binary code, a unary code, a truncated unary code, a predetermined binary code, etc. The binstring represents information as a series of binary numbers. The binstring can be composed of at least one bit. The image decoding device (100) can obtain segmentation shape mode information corresponding to the binstring based on a segmentation rule. The image decoding device (100) can determine whether to quad-segment an encoding unit, whether not to quad-segment, or the segmentation direction and segmentation type based on a single binstring.

[0091] The coding unit may be smaller than or equal to the maximum coding unit. For example, the maximum coding unit is also a coding unit with the maximum size, so it is a coding unit. If the split shape mode information for the maximum coding unit indicates that it is not split, the coding unit determined from the maximum coding unit has the same size as the maximum coding unit. If the split shape mode information for the maximum coding unit indicates that it is split, the maximum coding unit may be split into coding units. In addition, if the split shape mode information for the coding unit indicates splitting, the coding units may be split into coding units of smaller sizes. However, the splitting of the image is not limited thereto, and the maximum coding unit and the coding units may not be distinguished. The splitting of the coding unit is described in more detail with reference to FIGS. 3 to 16.

[0092] Additionally, one or more prediction blocks for prediction may be determined from the coding unit. The prediction blocks may be equal to or smaller than the coding unit. Additionally, one or more transformation blocks for transformation may be determined from the coding unit. The transformation blocks may be equal to or smaller than the coding unit.

[0093] The shape and size of the transformation block and the prediction block may be unrelated.

[0094] In another embodiment, prediction may be performed using the encoding unit as a prediction block. Transformation may also be performed using the encoding unit as a transform block.

[0095] The division of a coding unit is described in more detail with reference to FIGS. 3 to 16. The current block and neighboring blocks of the present disclosure may represent one of a maximum coding unit, a coding unit, a prediction block, and a transform block. In addition, the current block or the current coding unit is a block currently being decoded or encoded, or a block currently being divided. The neighboring block may be a block reconstructed before the current block. The neighboring block may be spatially or temporally adjacent to the current block. The neighboring block may be located on one of the lower left, left, upper left, upper right, upper right, right, and lower right sides of the current block.

[0096] FIG. 3 illustrates a process in which an image decoding device divides a current encoding unit to determine at least one encoding unit according to one embodiment.

[0097] The block shape may include 4Nx4N, 4Nx2N, 2Nx4N, 4NxN, Nx4N, 32NxN, Nx32N, 16NxN, Nx16N, 8NxN or Nx8N, where N may be a positive integer. The block shape information is information indicating at least one of the shape, direction, width and height ratio or size of the encoding unit.

[0098] The shape of the encoding unit may include square and non-square. When the width and height of the encoding unit are equal (i.e., when the block shape of the encoding unit is 4Nx4N), the image decoding device (100) may determine the block shape information of the encoding unit as square. The image decoding device (100) may determine the shape of the encoding unit as non-square.

[0099] When the width and height of the encoding unit are different (i.e., when the block shape of the encoding unit is 4Nx2N, 2Nx4N, 4NxN, Nx4N, 32NxN, Nx32N, 16NxN, Nx16N, 8NxN, or Nx8N), the image decoding device (100) may determine the block shape information of the encoding unit to be non-square. When the shape of the encoding unit is non-square, the image decoding device (100) may determine the ratio of the width and height among the block shape information of the encoding unit to be at least one of 1:2, 2:1, 1:4, 4:1, 1:8, 8:1, 1:16, 16:1, 1:32, and 32:1. Additionally, based on the width length and height length of the encoding unit, the image decoding device (100) can determine whether the encoding unit is in the horizontal or vertical direction. Additionally, based on at least one of the width length, height length, or area of ​​the encoding unit, the image decoding device (100) can determine the size of the encoding unit.

[0100] According to one embodiment, the image decoding device (100) can determine the shape of an encoding unit using block shape information, and can determine the shape into which the encoding unit is divided using segmentation shape mode information. That is, the splitting method of the encoding unit indicated by the segmentation shape mode information can be determined depending on which block shape the block shape information used by the image decoding device (100) indicates.

[0101] The image decoding device (100) can obtain the split shape mode information from the bitstream. However, the present invention is not limited thereto, and the image decoding device (100) and the image encoding device (2200) can determine the pre-agreed split shape mode information based on the block shape information. The image decoding device (100) can determine the pre-agreed split shape mode information for the maximum coding unit or the minimum coding unit. For example, the image decoding device (100) can determine the split shape mode information for the maximum coding unit as quad split. In addition, the image decoding device (100) can determine the split shape mode information for the minimum coding unit as “not split.” Specifically, the image decoding device (100) can determine the size of the maximum coding unit as 256x256. The image decoding device (100) can determine the pre-agreed split shape mode information as quad split. Quad splitting is a splitting mode that divides both the width and height of an encoding unit in half. The image decoding device (100) can obtain a coding unit of size 128x128 from a maximum coding unit of size 256x256 based on the splitting mode information. In addition, the image decoding device (100) can determine the size of the minimum coding unit as 4x4. The image decoding device (100) can obtain splitting mode information indicating "not splitting" for the minimum coding unit.

[0102] According to one embodiment, the image decoding device (100) may use block shape information indicating that the current encoding unit is a square shape. For example, the image decoding device (100) may determine whether to not split a square encoding unit, to split it vertically, to split it horizontally, to split it into four encoding units, etc., according to the split shape mode information. Referring to FIG. 3, when the block shape information of the current encoding unit (300) indicates a square shape, the decoding unit (120) may not split an encoding unit (310a) having the same size as the current encoding unit (300) according to the split shape mode information indicating that it is not split, or may determine a split encoding unit (310b, 310c, 310d, 310e, 310f, etc.) based on the split shape mode information indicating a predetermined splitting method.

[0103] Referring to FIG. 3, the image decoding device (100) may determine two coding units (310b) by vertically dividing the current coding unit (300) based on the split shape mode information indicating that the current coding unit (300) is vertically divided, according to an embodiment. The image decoding device (100) may determine two coding units (310c) by horizontally dividing the current coding unit (300) based on the split shape mode information indicating that the current coding unit (300) is horizontally divided, according to an embodiment. The image decoding device (100) may determine four coding units (310d) by vertically and horizontally dividing the current coding unit (300) based on the split shape mode information indicating that the current coding unit (300) is vertically and horizontally divided, according to an embodiment. The image decoding device (100) may determine three coding units (310e) by vertically dividing the current coding unit (300) based on the split shape mode information indicating that the current coding unit (300) is ternary divided, according to an embodiment. The image decoding device (100) can determine three coding units (310f) into which the current coding unit (300) is horizontally divided based on the division shape mode information indicating that the ternary division is horizontally divided. However, the division shapes into which a square coding unit can be divided should not be interpreted as being limited to the above-described shapes, and may include various shapes that can be indicated by the division shape mode information. Specified division shapes into which a square coding unit is divided will be specifically described below through various embodiments.

[0104] FIG. 4 illustrates a process in which an image decoding device determines at least one encoding unit by dividing a non-square encoding unit according to one embodiment.

[0105] According to one embodiment, the image decoding device (100) may utilize block shape information indicating that the current encoding unit is non-square. The image decoding device (100) may determine whether to not split the current non-square encoding unit or to split it using a predetermined method based on the split shape mode information. Referring to FIG. 4, when the block shape information of the current encoding unit (400 or 450) indicates a non-square shape, the image decoding device (100) may determine an encoding unit (410 or 460) having the same size as the current encoding unit (400 or 450) according to the split shape mode information indicating that it is not split, or may determine a split encoding unit (420a, 420b, 430a, 430b, 430c, 470a, 470b, 480a, 480b, 480c) based on the split shape mode information indicating a predetermined splitting method. The predetermined splitting method by which a non-square encoding unit is split will be described in detail through various embodiments below.

[0106] According to one embodiment, the image decoding device (100) may determine a form in which an encoding unit is split using split form mode information, and in this case, the split form mode information may indicate the number of at least one encoding unit generated by splitting the encoding unit. Referring to FIG. 4, when the split form mode information indicates that the current encoding unit (400 or 450) is split into two encoding units, the image decoding device (100) may split the current encoding unit (400 or 450) based on the split form mode information to determine two encoding units (420a, 420b, or 470a, 470b) included in the current encoding unit.

[0107] According to one embodiment, when the image decoding device (100) splits a current encoding unit (400 or 450) having a non-square shape based on split shape mode information, the image decoding device (100) may split the current encoding unit by considering the position of the long side of the non-square current encoding unit (400 or 450). For example, the image decoding device (100) may split the current encoding unit (400 or 450) in a direction that splits the long side of the current encoding unit (400 or 450) by considering the shape of the current encoding unit (400 or 450) to determine a plurality of encoding units.

[0108] According to one embodiment, if the split shape mode information indicates that the coding unit is split into an odd number of blocks (ternary splitting), the image decoding device (100) may determine an odd number of coding units included in the current coding unit (400 or 450). For example, if the split shape mode information indicates that the current coding unit (400 or 450) is split into three coding units, the image decoding device (100) may split the current coding unit (400 or 450) into three coding units (430a, 430b, 430c, 480a, 480b, 480c).

[0109] According to one embodiment, the ratio of the width and height of the current encoding unit (400 or 450) may be 4:1 or 1:4. When the ratio of the width and height is 4:1, the block shape information may be in the horizontal direction because the length of the width is longer than the length of the height. When the ratio of the width and height is 1:4, the block shape information may be in the vertical direction because the length of the width is shorter than the length of the height. The image decoding device (100) may determine to split the current encoding unit into an odd number of blocks based on the split shape mode information. In addition, the image decoding device (100) may determine the splitting direction of the current encoding unit (400 or 450) based on the block shape information of the current encoding unit (400 or 450). For example, if the current encoding unit (400) is in the vertical direction, the image decoding device (100) can divide the current encoding unit (400) in the horizontal direction to determine encoding units (430a, 430b, 430c). Also, if the current encoding unit (450) is in the horizontal direction, the image decoding device (100) can divide the current encoding unit (450) in the vertical direction to determine encoding units (480a, 480b, 480c).

[0110] According to one embodiment, the image decoding device (100) may determine an odd number of coding units included in the current coding unit (400 or 450), and the sizes of the determined coding units may not all be the same. For example, among the determined odd number of coding units (430a, 430b, 430c, 480a, 480b, 480c), the size of a given coding unit (430b or 480b) may have a different size from the other coding units (430a, 430c, 480a, 480c). That is, the encoding units into which the current encoding unit (400 or 450) can be divided and determined can have multiple types of sizes, and in some cases, an odd number of encoding units (430a, 430b, 430c, 480a, 480b, 480c) can each have different sizes.

[0111] According to one embodiment, when the split shape mode information indicates that the coding unit is split into an odd number of blocks, the image decoding device (100) can determine an odd number of coding units included in the current coding unit (400 or 450), and further, the image decoding device (100) can place a predetermined restriction on at least one coding unit among the odd number of coding units generated by splitting. Referring to FIG. 4, the image decoding device (100) can perform a decoding process for a coding unit (430b, 480b) located in the center among three coding units (430a, 430b, 430c, 480a, 480b, 480c) generated by splitting the current coding unit (400 or 450) differently from the decoding process for other coding units (430a, 430c, 480a, 480c). For example, the image decoding device (100) can restrict the encoding unit (430b, 480b) located in the center from being split any further, unlike other encoding units (430a, 430c, 480a, 480c), or can restrict it to be split only a predetermined number of times.

[0112] FIG. 5 illustrates a process in which an image decoding device divides an encoding unit based on at least one of block shape information and division shape mode information, according to one embodiment.

[0113] According to one embodiment, the image decoding device (100) may determine whether to split or not to split a first coding unit (500) having a square shape into coding units based on at least one of block shape information and split shape mode information. According to one embodiment, when the split shape mode information indicates splitting the first coding unit (500) in the horizontal direction, the image decoding device (100) may split the first coding unit (500) in the horizontal direction to determine a second coding unit (510). The first coding unit, the second coding unit, and the third coding unit used according to one embodiment are terms used to understand the relationship before and after splitting between coding units. For example, when the first coding unit is split, the second coding unit may be determined, and when the second coding unit is split, the third coding unit may be determined. Hereinafter, the relationship between the first coding unit, the second coding unit, and the third coding unit used may be understood to follow the above-described characteristics.

[0114] According to one embodiment, the image decoding device (100) may determine to split or not split the determined second encoding unit (510) into encoding units based on the split shape mode information. Referring to FIG. 5, the image decoding device (100) may split the first encoding unit (500) based on the split shape mode information to split the determined second encoding unit (510) of a non-square shape into at least one third encoding unit (520a, 520b, 520c, 520d, etc.) or may not split the second encoding unit (510). The image decoding device (100) can obtain split shape mode information, and the image decoding device (100) can split the first encoding unit (500) based on the obtained split shape mode information to split a plurality of second encoding units (e.g., 510) of various shapes, and the second encoding unit (510) can be split according to the way in which the first encoding unit (500) is split based on the split shape mode information. According to one embodiment, when the first encoding unit (500) is split into the second encoding unit (510) based on the split shape mode information for the first encoding unit (500), the second encoding unit (510) can also be split into the third encoding unit (e.g., 520a, 520b, 520c, 520d, etc.) based on the split shape mode information for the second encoding unit (510). That is, the coding unit can be recursively split based on the split shape mode information associated with each coding unit. Accordingly, a square coding unit can be determined from a non-square coding unit, and such a square coding unit can be recursively split to determine a non-square coding unit.

[0115] Referring to FIG. 5, among the odd number of third coding units (520b, 520c, 520d) determined by splitting the second coding unit (510) having a non-square shape, a predetermined coding unit (e.g., a coding unit located in the middle or a coding unit having a square shape) may be split recursively. According to an embodiment, the third coding unit (520b) having a square shape, which is one of the odd number of third coding units (520b, 520c, 520d), may be split horizontally into a plurality of fourth coding units. The fourth coding unit (530b or 530d) having a non-square shape, which is one of the plurality of fourth coding units (530a, 530b, 530c, 530d), may be split again into a plurality of coding units. For example, the fourth coding unit (530b or 530d) having a non-square shape may be further divided into an odd number of coding units. Methods that can be used for recursive division of coding units will be described later through various embodiments.

[0116] According to one embodiment, the image decoding device (100) may split each of the third encoding units (520a, 520b, 520c, 520d, etc.) into encoding units based on the split shape mode information. In addition, the image decoding device (100) may determine not to split the second encoding unit (510) based on the split shape mode information. According to one embodiment, the image decoding device (100) may split the second encoding unit (510) having a non-square shape into an odd number of third encoding units (520b, 520c, 520d). The image decoding device (100) may place a predetermined restriction on a predetermined third encoding unit among the odd number of third encoding units (520b, 520c, 520d). For example, the image decoding device (100) can limit the encoding unit (520c) located in the middle among an odd number of third encoding units (520b, 520c, 520d) to not be divided any further or to be divided a settable number of times.

[0117] Referring to FIG. 5, the image decoding device (100) may limit the coding unit (520c) located in the middle among the odd number of third coding units (520b, 520c, 520d) included in the second coding unit (510) having a non-square shape to not be split any further, or to be split in a predetermined split form (for example, to be split only into four coding units or to be split in a form corresponding to the split form of the second coding unit (510), or to be split only a predetermined number of times (for example, to be split only n times, where n>0). However, the above limitations on the coding unit (520c) located in the middle are merely simple embodiments and should not be interpreted as being limited to the above-described embodiments, but should be interpreted as including various limitations in which the coding unit (520c) located in the middle can be decoded differently from the other coding units (520b, 520d).

[0118] According to one embodiment, the image decoding device (100) can obtain the segmentation shape mode information used to segment the current encoding unit from a predetermined location within the current encoding unit.

[0119] FIG. 6 illustrates a method for a video decoding device to determine a predetermined encoding unit among an odd number of encoding units according to one embodiment.

[0120] Referring to FIG. 6, the split shape mode information of the current encoding unit (600, 650) can be obtained from a sample at a predetermined position among a plurality of samples included in the current encoding unit (600, 650) (for example, a sample (640, 690) located in the center). However, the predetermined position within the current encoding unit (600) from which at least one of the split shape mode information can be obtained should not be interpreted as being limited to the center position illustrated in FIG. 6, but should be interpreted as including various positions (for example, top, bottom, left, right, upper left, lower left, upper right, or lower right, etc.) that can be included within the current encoding unit (600). The image decoding device (100) can obtain the split shape mode information obtained from the predetermined position and determine whether or not to split the current encoding unit into encoding units of various shapes and sizes.

[0121] According to one embodiment, the image decoding device (100) may select one of the coding units when the current coding unit is divided into a predetermined number of coding units. Various methods may be used to select one of the multiple coding units, and descriptions of such methods will be provided later through various embodiments.

[0122] According to one embodiment, the image decoding device (100) can divide the current encoding unit into a plurality of encoding units and determine an encoding unit at a predetermined position.

[0123] According to one embodiment, the image decoding device (100) may use information indicating the positions of each of the odd-numbered coding units to determine an coding unit located in the middle of the odd-numbered coding units. Referring to FIG. 6, the image decoding device (100) may divide the current coding unit (600) or the current coding unit (650) to determine odd-numbered coding units (620a, 620b, 620c) or odd-numbered coding units (660a, 660b, 660c). The image decoding device (100) may use information about the positions of the odd-numbered coding units (620a, 620b, 620c) or odd-numbered coding units (660a, 660b, 660c) to determine the middle coding unit (620b) or the middle coding unit (660b). For example, the image decoding device (100) can determine the coding unit (620b) located in the center by determining the positions of the coding units (620a, 620b, 620c) based on information indicating the positions of predetermined samples included in the coding units (620a, 620b, 620c). Specifically, the image decoding device (100) can determine the coding unit (620b) located in the center by determining the positions of the coding units (620a, 620b, 620c) based on information indicating the positions of samples (630a, 630b, 630c) at the upper left of the coding units (620a, 620b, 620c).

[0124] According to one embodiment, information indicating the positions of the upper left samples (630a, 630b, 630c) included in each of the coding units (620a, 620b, 620c) may include information on the positions or coordinates of the coding units (620a, 620b, 620c) within the picture. According to one embodiment, information indicating the positions of the upper left samples (630a, 630b, 630c) included in each of the coding units (620a, 620b, 620c) may include information indicating the width or height of the coding units (620a, 620b, 620c) included in the current coding unit (600), and this width or height may correspond to information indicating the difference between the coordinates of the coding units (620a, 620b, 620c) within the picture. That is, the image decoding device (100) can determine the encoding unit (620b) located in the center by directly using information about the positions or coordinates of the encoding units (620a, 620b, 620c) within the picture or by using information about the width or height of the encoding unit corresponding to the difference between the coordinates.

[0125] According to one embodiment, information indicating the position of the sample (630a) at the upper left of the upper encoding unit (620a) may represent (xa, ya) coordinates, information indicating the position of the sample (530b) at the upper left of the middle encoding unit (620b) may represent (xb, yb) coordinates, and information indicating the position of the sample (630c) at the upper left of the lower encoding unit (620c) may represent (xc, yc) coordinates. The image decoding device (100) may determine the middle encoding unit (620b) using the coordinates of the upper left samples (630a, 630b, 630c) included in the encoding units (620a, 620b, 620c), respectively. For example, when the coordinates of the samples (630a, 630b, 630c) on the upper left are sorted in ascending or descending order, the encoding unit (620b) including the coordinates (xb, yb) of the sample (630b) located in the center can be determined as the encoding unit located in the center among the encoding units (620a, 620b, 620c) determined by dividing the current encoding unit (600). However, the coordinates indicating the positions of the upper left samples (630a, 630b, 630c) may indicate coordinates indicating the absolute positions within the picture, and further, based on the position of the upper left sample (630a) of the upper left coding unit (620a), the (dxb, dyb) coordinates, which are information indicating the relative position of the sample (630b) of the upper left of the middle coding unit (620b), and the (dxc, dyc) coordinates, which are information indicating the relative position of the sample (630c) of the upper left of the lower coding unit (620c), may be used. In addition, the method of determining the coding unit of a given position by using the coordinates of the corresponding sample as information indicating the position of the sample included in the coding unit should not be interpreted as being limited to the above-described method, but should be interpreted as various arithmetic methods that can utilize the coordinates of the sample.

[0126] According to one embodiment, the image decoding device (100) may divide the current encoding unit (600) into a plurality of encoding units (620a, 620b, 620c), and select an encoding unit from among the encoding units (620a, 620b, 620c) according to a predetermined criterion. For example, the image decoding device (100) may select an encoding unit (620b) having a different size from among the encoding units (620a, 620b, 620c).

[0127] According to one embodiment, the image decoding device (100) may determine the width or height of each of the encoding units (620a, 620b, 620c) by using the (xa, ya) coordinate, which is information indicating the position of the sample (630a) at the upper left of the upper encoding unit (620a), the (xb, yb) coordinate, which is information indicating the position of the sample (630b) at the upper left of the middle encoding unit (620b), and the (xc, yc) coordinate, which is information indicating the position of the sample (630c) at the upper left of the lower encoding unit (620c). The image decoding device (100) can determine the size of each of the encoding units (620a, 620b, 620c) using coordinates (xa, ya), (xb, yb), (xc, yc) indicating the positions of the encoding units (620a, 620b, 620c). According to one embodiment, the image decoding device (100) can determine the width of the upper encoding unit (620a) as the width of the current encoding unit (600). The image decoding device (100) can determine the height of the upper encoding unit (620a) as yb-ya. According to one embodiment, the image decoding device (100) can determine the width of the middle encoding unit (620b) as the width of the current encoding unit (600). The image decoding device (100) may determine the height of the middle encoding unit (620b) as yc-yb. According to one embodiment, the image decoding device (100) may determine the width or height of the lower encoding unit using the width or height of the current encoding unit and the width and height of the upper encoding unit (620a) and the middle encoding unit (620b). The image decoding device (100) may determine an encoding unit having a different size from other encoding units based on the width and height of the determined encoding units (620a, 620b, 620c).Referring to FIG. 6, the image decoding device (100) can determine the middle encoding unit (620b) having a different size from the sizes of the upper encoding unit (620a) and the lower encoding unit (620c) as the encoding unit of a predetermined position. However, the process by which the image decoding device (100) described above determines the encoding unit having a different size from other encoding units is merely an embodiment of determining the encoding unit of a predetermined position using the size of the encoding unit determined based on sample coordinates, and therefore, various processes of determining the encoding unit of a predetermined position by comparing the sizes of the encoding units determined according to predetermined sample coordinates can be used.

[0128] The image decoding device (100) can determine the width or height of each of the encoding units (660a, 660b, 660c) by using the (xd, yd) coordinate, which is information indicating the position of the sample (670a) at the upper left of the left encoding unit (660a), the (xe, ye) coordinate, which is information indicating the position of the sample (670b) at the upper left of the middle encoding unit (660b), and the (xf, yf) coordinate, which is information indicating the position of the sample (670c) at the upper left of the right encoding unit (660c). The image decoding device (100) can determine the size of each of the encoding units (660a, 660b, 660c) by using the (xd, yd), (xe, ye), (xf, yf), which are coordinates indicating the positions of the encoding units (660a, 660b, 660c).

[0129] According to one embodiment, the image decoding device (100) may determine the width of the left encoding unit (660a) as xe-xd. The image decoding device (100) may determine the height of the left encoding unit (660a) as the height of the current encoding unit (650). According to one embodiment, the image decoding device (100) may determine the width of the middle encoding unit (660b) as xf-xe. The image decoding device (100) may determine the height of the middle encoding unit (660b) as the height of the current encoding unit (600). According to one embodiment, the image decoding device (100) may determine the width or height of the right encoding unit (660c) using the width or height of the current encoding unit (650) and the widths and heights of the left encoding unit (660a) and the middle encoding unit (660b). The image decoding device (100) can determine an encoding unit having a different size from other encoding units based on the width and height of the determined encoding units (660a, 660b, 660c). Referring to FIG. 6, the image decoding device (100) can determine a middle encoding unit (660b) having a different size from the sizes of the left encoding unit (660a) and the right encoding unit (660c) as an encoding unit at a predetermined position. However, the process of the image decoding device (100) described above determining an encoding unit having a different size from other encoding units is merely an embodiment of determining an encoding unit at a predetermined position using the size of the encoding unit determined based on sample coordinates, and therefore, various processes of determining an encoding unit at a predetermined position by comparing the sizes of the encoding units determined according to predetermined sample coordinates can be used.

[0130] However, the location of the sample considered for determining the location of the encoding unit should not be interpreted as being limited to the upper left corner described above, and it can be interpreted that information on the location of any sample included in the encoding unit can be used.

[0131] According to one embodiment, the image decoding device (100) may select an encoding unit at a predetermined position from among an odd number of encoding units determined by splitting the current encoding unit, taking into consideration the shape of the current encoding unit. For example, if the current encoding unit has a non-square shape in which the width is longer than the height, the image decoding device (100) may determine an encoding unit at a predetermined position in the horizontal direction. That is, the image decoding device (100) may determine one of the encoding units whose positions vary in the horizontal direction and place a restriction on the corresponding encoding unit. If the current encoding unit has a non-square shape in which the height is longer than the width, the image decoding device (100) may determine an encoding unit at a predetermined position in the vertical direction. That is, the image decoding device (100) may determine one of the encoding units whose positions vary in the vertical direction and place a restriction on the corresponding encoding unit.

[0132] According to one embodiment, the image decoding device (100) may use information indicating the positions of each of the even-numbered coding units to determine the coding unit at a predetermined position among the even-numbered coding units. The image decoding device (100) may determine the even-numbered coding units by dividing the current coding unit (binary dividing) and may determine the coding unit at a predetermined position using information about the positions of the even-numbered coding units. A specific process for this may be a process corresponding to the process of determining the coding unit at a predetermined position (e.g., the center position) among the odd-numbered coding units described above in FIG. 6, and thus will be omitted.

[0133] According to one embodiment, when a current encoding unit having a non-square shape is split into a plurality of encoding units, predetermined information about the encoding unit at a predetermined position may be used during the splitting process to determine an encoding unit at a predetermined position among the plurality of encoding units. For example, the image decoding device (100) may use at least one of block shape information and split shape mode information stored in a sample included in a middle encoding unit during the splitting process to determine an encoding unit located in the middle among the encoding units into which the current encoding unit is split.

[0134] Referring to FIG. 6, the image decoding device (100) can split the current encoding unit (600) into a plurality of encoding units (620a, 620b, 620c) based on the split shape mode information, and can determine the encoding unit (620b) located in the middle among the plurality of encoding units (620a, 620b, 620c). Furthermore, the image decoding device (100) can determine the encoding unit (620b) located in the middle by considering the position where the split shape mode information is acquired. That is, the split shape mode information of the current encoding unit (600) can be obtained from a sample (640) located in the center of the current encoding unit (600), and when the current encoding unit (600) is split into a plurality of encoding units (620a, 620b, 620c) based on the split shape mode information, the encoding unit (620b) including the sample (640) can be determined as the encoding unit located in the center. However, the information used to determine the encoding unit located in the center should not be interpreted as being limited to the split shape mode information, and various types of information can be used in the process of determining the encoding unit located in the center.

[0135] According to one embodiment, predetermined information for identifying a coding unit at a predetermined position may be obtained from a predetermined sample included in the coding unit to be determined. Referring to FIG. 6, the image decoding device (100) may use split shape mode information obtained from a sample at a predetermined position within the current coding unit (600) (e.g., a sample located at the center of the current coding unit (600)) to determine a coding unit at a predetermined position among a plurality of coding units (620a, 620b, 620c) determined by splitting the current coding unit (600) (e.g., a coding unit located at the center of the coding units split into multiple units). That is, the image decoding device (100) can determine the sample at the predetermined position by considering the block shape of the current encoding unit (600), and the image decoding device (100) can determine an encoding unit (620b) that includes a sample from which predetermined information (e.g., division shape mode information) can be obtained among a plurality of encoding units (620a, 620b, 620c) determined by dividing the current encoding unit (600), and can set a predetermined restriction. Referring to FIG. 6, according to one embodiment, the image decoding device (100) can determine a sample (640) located at the center of the current encoding unit (600) as a sample from which predetermined information can be obtained, and the image decoding device (100) can set a predetermined restriction on the encoding unit (620b) that includes such a sample (640) during the decoding process. However, the location of the sample from which certain information can be obtained should not be interpreted as being limited to the above-described location, but may be interpreted as samples at any location included in the encoding unit (620b) to be determined in order to set a limitation.

[0136] According to one embodiment, the position of a sample from which predetermined information can be obtained may be determined according to the shape of the current encoding unit (600). According to one embodiment, the block shape information may determine whether the shape of the current encoding unit is square or non-square, and may determine the position of a sample from which predetermined information can be obtained according to the shape. For example, the image decoding apparatus (100) may determine a sample located on a boundary that divides at least one of the width and height of the current encoding unit in half as a sample from which predetermined information can be obtained, using at least one of information about the width and information about the height of the current encoding unit. As another example, when the block shape information related to the current encoding unit indicates that the shape is non-square, the image decoding apparatus (100) may determine one of the samples adjacent to the boundary that divides the long side of the current encoding unit in half as a sample from which predetermined information can be obtained.

[0137] According to one embodiment, when the image decoding device (100) divides the current encoding unit into a plurality of encoding units, the image decoding device (100) may use the split shape mode information to determine the encoding unit at a predetermined position among the plurality of encoding units. According to one embodiment, the image decoding device (100) may obtain the split shape mode information from a sample at a predetermined position included in the encoding unit, and the image decoding device (100) may divide the plurality of encoding units generated by splitting the current encoding unit using the split shape mode information obtained from the sample at a predetermined position included in each of the plurality of encoding units. That is, the encoding unit may be recursively divided using the split shape mode information obtained from the sample at a predetermined position included in each of the encoding units. Since the recursive division process of the encoding unit has been described above with reference to FIG. 5, a detailed description thereof will be omitted.

[0138] According to one embodiment, the image decoding device (100) can divide a current encoding unit to determine at least one encoding unit, and can determine the order in which the at least one encoding unit is decoded according to a predetermined block (e.g., the current encoding unit).

[0139] FIG. 7 illustrates the order in which multiple encoding units are processed when an image decoding device determines multiple encoding units by dividing a current encoding unit according to one embodiment.

[0140] According to one embodiment, the image decoding device (100) may determine second encoding units (710a, 710b) by vertically splitting the first encoding unit (700) according to the splitting shape mode information, determine second encoding units (730a, 730b) by horizontally splitting the first encoding unit (700), or determine second encoding units (750a, 750b, 750c, 750d) by vertically and horizontally splitting the first encoding unit (700).

[0141] Referring to FIG. 7, the image decoding device (100) can determine the order in which the second encoding units (710a, 710b) determined by vertically dividing the first encoding unit (700) are processed in the horizontal direction (710c). The image decoding device (100) can determine the order in which the second encoding units (730a, 730b) determined by horizontally dividing the first encoding unit (700) are processed in the vertical direction (730c). The image decoding device (100) can determine the second encoding units (750a, 750b, 750c, 750d) determined by dividing the first encoding unit (700) in the vertical and horizontal directions according to a predetermined order (e.g., raster scan order (750e) or z scan order (z scan order)) in which encoding units located in one row are processed and then encoding units located in the next row are processed.

[0142] According to one embodiment, the image decoding device (100) can recursively split the encoding units. Referring to FIG. 7, the image decoding device (100) can split the first encoding unit (700) to determine a plurality of encoding units (710a, 710b, 730a, 730b, 750a, 750b, 750c, 750d), and can recursively split each of the determined plurality of encoding units (710a, 710b, 730a, 730b, 750a, 750b, 750c, 750d). A method for splitting a plurality of coding units (710a, 710b, 730a, 730b, 750a, 750b, 750c, 750d) may be a method corresponding to a method for splitting the first coding unit (700). Accordingly, the plurality of coding units (710a, 710b, 730a, 730b, 750a, 750b, 750c, 750d) may each be independently split into a plurality of coding units. Referring to FIG. 7, the image decoding device (100) may split the first coding unit (700) in the vertical direction to determine the second coding units (710a, 710b), and further may determine to independently split or not split each of the second coding units (710a, 710b).

[0143] According to one embodiment, the image decoding device (100) may horizontally divide the second encoding unit (710a) on the left into third encoding units (720a, 720b), and may not divide the second encoding unit (710b) on the right.

[0144] According to one embodiment, the processing order of the coding units may be determined based on the splitting process of the coding units. In other words, the processing order of the split coding units may be determined based on the processing order of the coding units immediately before splitting. The image decoding device (100) may determine the processing order of the third coding units (720a, 720b) ​​determined by splitting the second coding unit (710a) on the left, independently from the second coding unit (710b) on the right. Since the second coding unit (710a) on the left is split horizontally and the third coding units (720a, 720b) ​​are determined, the third coding units (720a, 720b) ​​may be processed in the vertical direction (720c). In addition, since the order in which the second encoding unit (710a) on the left and the second encoding unit (710b) on the right are processed corresponds to the horizontal direction (710c), the right encoding unit (710b) can be processed after the third encoding units (720a, 720b) ​​included in the second encoding unit (710a) on the left are processed in the vertical direction (720c). Since the above-described content is intended to explain the process in which the processing order of the encoding units is determined according to the encoding units before splitting, it should not be interpreted as being limited to the above-described embodiment, but should be interpreted as being used in various ways in which encoding units that are split and determined in various forms can be independently processed according to a predetermined order.

[0145] FIG. 8 illustrates a process for determining that a current encoding unit is divided into an odd number of encoding units when the encoding units cannot be processed in a predetermined order, according to one embodiment.

[0146] According to one embodiment, the image decoding device (100) may determine that the current encoding unit is split into an odd number of encoding units based on the acquired split shape mode information. Referring to FIG. 8, a first encoding unit (800) having a square shape may be split into second encoding units (810a, 810b) having a non-square shape, and the second encoding units (810a, 810b) may each be independently split into third encoding units (820a, 820b, 820c, 820d, 820e). According to one embodiment, the image decoding device (100) can determine a plurality of third encoding units (820a, 820b) by horizontally dividing the left encoding unit (810a) among the second encoding units, and can divide the right encoding unit (810b) into an odd number of third encoding units (820c, 820d, 820e).

[0147] According to one embodiment, the image decoding device (100) can determine whether there is an odd number of split coding units by determining whether the third coding units (820a, 820b, 820c, 820d, 820e) can be processed in a predetermined order. Referring to FIG. 8, the image decoding device (100) can determine the third coding units (820a, 820b, 820c, 820d, 820e) by recursively splitting the first coding unit (800). The image decoding device (100) can determine whether the first encoding unit (800), the second encoding unit (810a, 810b), or the third encoding unit (820a, 820b, 820c, 820d, 820e) is divided into an odd number of encoding units based on at least one of the block shape information and the split shape mode information. For example, the encoding unit located on the right side of the second encoding unit (810a, 810b) can be divided into an odd number of third encoding units (820c, 820d, 820e). The order in which the plurality of encoding units included in the first encoding unit (800) are processed can be a predetermined order (e.g., z-scan order (830)), and the image decoding device (100) can determine whether the third encoding unit (820c, 820d, 820e) determined by dividing the second encoding unit (810b) on the right into odd numbers satisfies the condition that it can be processed according to the predetermined order.

[0148] According to one embodiment, the image decoding device (100) may determine whether the third encoding units (820a, 820b, 820c, 820d, 820e) included in the first encoding unit (800) satisfy a condition that they can be processed in a predetermined order, and the condition is related to whether at least one of the width and height of the second encoding unit (810a, 810b) is split in half according to the boundary of the third encoding unit (820a, 820b, 820c, 820d, 820e). For example, the third encoding unit (820a, 820b) determined by splitting the height of the left second encoding unit (810a) of a non-square shape in half may satisfy the condition. Since the boundaries of the third encoding units (820c, 820d, 820e) determined by dividing the right second encoding unit (810b) into three encoding units do not divide the width or height of the right second encoding unit (810b) in half, it may be determined that the third encoding units (820c, 820d, 820e) do not satisfy the condition. In the case where this condition is not satisfied, the image decoding device (100) may determine that there is a disconnection in the scanning order, and may determine that the right second encoding unit (810b) is divided into an odd number of encoding units based on the determination result. According to an embodiment, the image decoding device (100) may place a predetermined restriction on an encoding unit at a predetermined position among the divided encoding units when the encoding unit is divided into an odd number of encoding units. Since the contents of such restrictions or predetermined positions have been described above through various embodiments, a detailed description thereof will be omitted.

[0149] FIG. 9 illustrates a process in which an image decoding device divides a first encoding unit to determine at least one encoding unit according to one embodiment.

[0150] According to one embodiment, the image decoding device (100) may split the first encoding unit (900) based on the split shape mode information obtained through the receiver (110). The first encoding unit (900) having a square shape may be split into four square-shaped encoding units or may be split into a plurality of non-square encoding units. For example, referring to FIG. 9, when the first encoding unit (900) is square and the split shape mode information indicates that it is split into non-square encoding units, the image decoding device (100) may split the first encoding unit (900) into a plurality of non-square encoding units. Specifically, when the split shape mode information indicates that the first encoding unit (900) is split in the horizontal direction or the vertical direction to determine an odd number of encoding units, the image decoding device (100) can split the first encoding unit (900) having a square shape into second encoding units (910a, 910b, 910c) determined by splitting them in the vertical direction into an odd number of encoding units or second encoding units (920a, 920b, 920c) determined by splitting them in the horizontal direction.

[0151] According to one embodiment, the image decoding device (100) can determine whether the second encoding units (910a, 910b, 910c, 920a, 920b, 920c) included in the first encoding unit (900) satisfy a condition that allows them to be processed in a predetermined order, and the condition is related to whether at least one of the width and height of the first encoding unit (900) is split in half according to the boundary of the second encoding units (910a, 910b, 910c, 920a, 920b, 920c). Referring to FIG. 9, since the boundaries of the second coding units (910a, 910b, 910c) determined by vertically dividing the first coding unit (900) in a square shape do not divide the width of the first coding unit (900) in half, it may be determined that the first coding unit (900) does not satisfy the condition that it can be processed in a predetermined order. In addition, since the boundaries of the second coding units (920a, 920b, 920c) determined by horizontally dividing the first coding unit (900) in a square shape do not divide the width of the first coding unit (900) in half, it may be determined that the first coding unit (900) does not satisfy the condition that it can be processed in a predetermined order. If such a condition is not satisfied, the image decoding device (100) may determine that the scan order is disconnected, and based on the determination result, may determine that the first encoding unit (900) is divided into an odd number of encoding units. According to one embodiment, the image decoding device (100) may place a predetermined restriction on an encoding unit at a predetermined position among the divided encoding units when the encoding unit is divided into an odd number of encoding units. Since the contents of such restrictions or predetermined positions, etc. have been described above through various embodiments, a detailed description thereof will be omitted.

[0152] According to one embodiment, the image decoding device (100) can divide the first encoding unit to determine encoding units of various shapes.

[0153] Referring to FIG. 9, the image decoding device (100) can divide the first encoding unit (900) having a square shape and the first encoding unit (930 or 950) having a non-square shape into encoding units of various shapes.

[0154] FIG. 10 illustrates that, according to one embodiment, a video decoding device limits the shapes into which a second encoding unit can be divided when a non-square shape of a second encoding unit determined by dividing a first encoding unit satisfies a predetermined condition.

[0155] According to one embodiment, the image decoding device (100) may determine to split a first coding unit (1000) having a square shape into second coding units (1010a, 1010b, 1020a, 1020b) having a non-square shape based on the split shape mode information obtained through the receiver (110). The second coding units (1010a, 1010b, 1020a, 1020b) may be split independently. Accordingly, the image decoding device (100) may determine to split or not split into a plurality of coding units based on the split shape mode information related to each of the second coding units (1010a, 1010b, 1020a, 1020b). According to one embodiment, the image decoding device (100) may determine third encoding units (1012a, 1012b) by horizontally dividing the left second encoding unit (1010a) having a non-square shape determined by vertically dividing the first encoding unit (1000). However, when the image decoding device (100) divides the left second encoding unit (1010a) in the horizontal direction, the right second encoding unit (1010b) may be restricted from being horizontally divided in the same direction as the direction in which the left second encoding unit (1010a) is divided. If the second encoding unit on the right (1010b) is split in the same direction to determine the third encoding unit (1014a, 1014b), the second encoding unit on the left (1010a) and the second encoding unit on the right (1010b) may be independently split in the horizontal direction to determine the third encoding unit (1012a, 1012b, 1014a, 1014b). However, this is the same result as the image decoding device (100) splitting the first encoding unit (1000) into four square-shaped second encoding units (1030a, 1030b, 1030c, 1030d) based on the split shape mode information, which may be inefficient in terms of image decoding.

[0156] According to one embodiment, the image decoding device (100) may determine third coding units (1022a, 1022b, 1024a, 1024b) by vertically dividing a second coding unit (1020a or 1020b) having a non-square shape determined by dividing a first coding unit (1000) in a horizontal direction. However, when the image decoding device (100) vertically divides one of the second coding units (e.g., the upper second coding unit (1020a)), the other second coding units (e.g., the lower coding unit (1020b)) may be restricted from being vertically divided in the same direction as the direction in which the upper second coding unit (1020a) is divided, for the reasons described above.

[0157] FIG. 11 illustrates a process of a video decoding device dividing a square-shaped encoding unit when the split shape mode information cannot indicate that the encoding unit is divided into four square-shaped encoding units according to one embodiment.

[0158] According to one embodiment, the image decoding device (100) may split the first encoding unit (1100) based on the split shape mode information to determine the second encoding units (1110a, 1110b, 1120a, 1120b, etc.). The split shape mode information may include information about various shapes into which the encoding unit may be split, but the information about various shapes may not include information for splitting the encoding unit into four encoding units having a square shape. According to this split shape mode information, the image decoding device (100) cannot split the first encoding unit (1100) having a square shape into four second encoding units having a square shape (1130a, 1130b, 1130c, 1130d). Based on the segmentation shape mode information, the image decoding device (100) can determine a second encoding unit (1110a, 1110b, 1120a, 1120b, etc.) of a non-square shape.

[0159] According to one embodiment, the image decoding device (100) can independently split each of the second encoding units (1110a, 1110b, 1120a, 1120b, etc.) having a non-square shape. Each of the second encoding units (1110a, 1110b, 1120a, 1120b, etc.) can be split in a predetermined order using a recursive method, which may be a splitting method corresponding to a method in which the first encoding unit (1100) is split based on splitting shape mode information.

[0160] For example, the image decoding device (100) can determine third coding units (1112a, 1112b) having a square shape by splitting the left second coding unit (1110a) in the horizontal direction, and can determine third coding units (1114a, 1114b) having a square shape by splitting the right second coding unit (1110b) in the horizontal direction. Furthermore, the image decoding device (100) can also determine third coding units (1116a, 1116b, 1116c, 1116d) having a square shape by splitting both the left second coding unit (1110a) and the right second coding unit (1110b) in the horizontal direction. In this case, the encoding unit can be determined in the same form as the first encoding unit (1100) being divided into four square-shaped second encoding units (1130a, 1130b, 1130c, 1130d).

[0161] As another example, the image decoding device (100) may determine third coding units (1122a, 1122b) having a square shape by vertically splitting the upper second coding unit (1120a), and may determine third coding units (1124a, 1124b) having a square shape by vertically splitting the lower second coding unit (1120b). Furthermore, the image decoding device (100) may determine third coding units (1126a, 1126b, 1126a, 1126b) having a square shape by vertically splitting both the upper second coding unit (1120a) and the lower second coding unit (1120b). In this case, the encoding unit can be determined in the same form as the first encoding unit (1100) being divided into four square-shaped second encoding units (1130a, 1130b, 1130c, 1130d).

[0162] FIG. 12 illustrates that, according to one embodiment, the processing order between multiple encoding units may vary depending on the process of dividing the encoding units.

[0163] According to one embodiment, the image decoding device (100) may split the first encoding unit (1200) based on the split shape mode information. If the block shape is square and the split shape mode information indicates that the first encoding unit (1200) is split in at least one of the horizontal direction and the vertical direction, the image decoding device (100) may split the first encoding unit (1200) to determine second encoding units (e.g., 1210a, 1210b, 1220a, 1220b, etc.). Referring to FIG. 12, the second encoding units (1210a, 1210b, 1220a, 1220b) having a non-square shape determined by splitting the first encoding unit 1200 only in the horizontal direction or the vertical direction may be independently split based on the split shape mode information for each. For example, the image decoding device (100) can determine third encoding units (1216a, 1216b, 1216c, 1216d) by horizontally dividing second encoding units (1210a, 1210b) generated by vertically dividing the first encoding unit (1200), and can determine third encoding units (1226a, 1226b, 1226c, 1226d) by horizontally dividing second encoding units (1220a, 1220b) generated by horizontally dividing the first encoding unit (1200). Since the process of dividing the second encoding units (1210a, 1210b, 1220a, 1220b) has been described above with reference to FIG. 11, a detailed description thereof will be omitted.

[0164] According to one embodiment, the image decoding device (100) can process encoding units according to a predetermined order. Since the characteristics of processing encoding units according to a predetermined order have been described above with reference to FIG. 7, a detailed description thereof will be omitted. Referring to FIG. 12, the image decoding device (100) can divide a first encoding unit (1200) having a square shape and determine four third encoding units (1216a, 1216b, 1216c, 1216d, 1226a, 1226b, 1226c, 1226d) having a square shape. According to one embodiment, the image decoding device (100) can determine the processing order of the third encoding units (1216a, 1216b, 1216c, 1216d, 1226a, 1226b, 1226c, 1226d) depending on the form in which the first encoding unit (1200) is divided.

[0165] According to one embodiment, the image decoding device (100) may determine third encoding units (1216a, 1216b, 1216c, 1216d) by horizontally dividing the second encoding units (1210a, 1210b) generated by vertically dividing them, and the image decoding device (100) may process the third encoding units (1216a, 1216b, 1216c, 1216d) according to an order (1217) of first processing the third encoding units (1216a, 1216c) included in the left second encoding unit (1210a) in the vertical direction and then processing the third encoding units (1216b, 1216d) included in the right second encoding unit (1210b) in the vertical direction.

[0166] According to one embodiment, the image decoding device (100) may determine third encoding units (1226a, 1226b, 1226c, 1226d) by vertically dividing the second encoding units (1220a, 1220b) generated by being divided in the horizontal direction, and the image decoding device (100) may process the third encoding units (1226a, 1226b, 1226c, 1226d) according to an order (1227) of first processing the third encoding units (1226a, 1226b) included in the upper second encoding unit (1220a) in the horizontal direction and then processing the third encoding units (1226c, 1226d) included in the lower second encoding unit (1220b) in the horizontal direction.

[0167] Referring to FIG. 12, the second encoding units (1210a, 1210b, 1220a, 1220b) can be divided into third encoding units (1216a, 1216b, 1216c, 1216d, 1226a, 1226b, 1226c, 1226d) having a square shape. The second encoding units (1210a, 1210b) determined by being split in the vertical direction and the second encoding units (1220a, 1220b) determined by being split in the horizontal direction are split into different shapes, but according to the third encoding units (1216a, 1216b, 1216c, 1216d, 1226a, 1226b, 1226c, 1226d) determined later, the first encoding unit (1200) is ultimately split into encoding units of the same shape. Accordingly, even if the image decoding device (100) determines encoding units of the same shape as a result by recursively splitting the encoding units through different processes based on the split shape mode information, it can process a plurality of encoding units determined in the same shape in different orders.

[0168] FIG. 13 illustrates a process in which the depth of an encoding unit is determined as the shape and size of the encoding unit change when the encoding unit is recursively divided to determine a plurality of encoding units according to one embodiment.

[0169] According to one embodiment, the image decoding device (100) may determine the depth of an encoding unit according to a predetermined criterion. For example, the predetermined criterion may be the length of a long side of the encoding unit. If the length of the long side of the current encoding unit is split to be 2n (n>0) times the length of the long side of the encoding unit before splitting, the image decoding device (100) may determine that the depth of the current encoding unit is increased by n compared to the depth of the encoding unit before splitting. Hereinafter, an encoding unit with an increased depth is expressed as an encoding unit of a lower depth.

[0170] Referring to FIG. 13, according to one embodiment, based on block shape information indicating a square shape (for example, the block shape information may indicate '0: SQUARE'), the image decoding device (100) may divide a first coding unit (1300) having a square shape to determine a second coding unit (1302), a third coding unit (1304), etc. of a lower depth. If the size of the first coding unit (1300) having a square shape is 2Nx2N, the second coding unit (1302) determined by dividing the width and height of the first coding unit (1300) by half may have a size of NxN. Furthermore, the third coding unit (1304) determined by dividing the width and height of the second coding unit (1302) by half may have a size of N / 2xN / 2. In this case, the width and height of the third encoding unit (1304) correspond to 1 / 4 of the width and height of the first encoding unit (1300). When the depth of the first encoding unit (1300) is D, the depth of the second encoding unit (1302), which is 1 / 2 of the width and height of the first encoding unit (1300), may be D+1, and the depth of the third encoding unit (1304), which is 1 / 4 of the width and height of the first encoding unit (1300), may be D+2.

[0171] According to one embodiment, based on block shape information indicating a non-square shape (for example, the block shape information may indicate '1: NS_VER' indicating a non-square shape in which the height is longer than the width or '2: NS_HOR' indicating a non-square shape in which the width is longer than the height), the image decoding device (100) may split a first coding unit (1310 or 1320) having a non-square shape to determine a second coding unit (1312 or 1322), a third coding unit (1314 or 1324) of a lower depth, etc.

[0172] The image decoding device (100) can determine a second encoding unit (e.g., 1302, 1312, 1322, etc.) by splitting at least one of the width and height of the first encoding unit (1310) having a size of Nx2N. That is, the image decoding device (100) can split the first encoding unit (1310) in the horizontal direction to determine a second encoding unit (1302) having a size of NxN or a second encoding unit (1322) having a size of NxN / 2, and can also split the first encoding unit (1310) in the horizontal direction and the vertical direction to determine a second encoding unit (1312) having a size of N / 2xN.

[0173] According to one embodiment, the image decoding device (100) may determine a second coding unit (e.g., 1302, 1312, 1322, etc.) by splitting at least one of the width and the height of the first coding unit (1320) having a size of 2NxN. That is, the image decoding device (100) may split the first coding unit (1320) in the vertical direction to determine a second coding unit (1302) having a size of NxN or a second coding unit (1312) having a size of N / 2xN, and may also split the first coding unit (1320) in the horizontal direction and the vertical direction to determine a second coding unit (1322) having a size of NxN / 2.

[0174] According to one embodiment, the image decoding device (100) may determine a third encoding unit (e.g., 1304, 1314, 1324, etc.) by splitting at least one of the width and the height of the second encoding unit (1302) having a size of NxN. That is, the image decoding device (100) may split the second encoding unit (1302) in the vertical direction and the horizontal direction to determine a third encoding unit (1304) having a size of N / 2xN / 2, a third encoding unit (1314) having a size of N / 4xN / 2, or a third encoding unit (1324) having a size of N / 2xN / 4.

[0175] According to one embodiment, the image decoding device (100) may determine a third encoding unit (e.g., 1304, 1314, 1324, etc.) by splitting at least one of the width and the height of the second encoding unit (1312) having a size of N / 2xN. That is, the image decoding device (100) may split the second encoding unit (1312) in the horizontal direction to determine a third encoding unit (1304) having a size of N / 2xN / 2 or a third encoding unit (1324) having a size of N / 2xN / 4, or split the second encoding unit (1312) in the vertical direction and the horizontal direction to determine a third encoding unit (1314) having a size of N / 4xN / 2.

[0176] According to one embodiment, the image decoding device (100) may determine a third encoding unit (e.g., 1304, 1314, 1324, etc.) by splitting at least one of the width and the height of the second encoding unit (1322) having a size of NxN / 2. That is, the image decoding device (100) may split the second encoding unit (1322) in the vertical direction to determine a third encoding unit (1304) having a size of N / 2xN / 2 or a third encoding unit (1314) having a size of N / 4xN / 2, or split the second encoding unit (1322) in the vertical direction and the horizontal direction to determine a third encoding unit (1324) having a size of N / 2xN / 4.

[0177] According to one embodiment, the image decoding device (100) may split a square-shaped encoding unit (e.g., 1300, 1302, 1304) in a horizontal direction or a vertical direction. For example, a first encoding unit (1300) having a size of 2Nx2N may be split in the vertical direction to determine a first encoding unit (1310) having a size of Nx2N, or may be split in the horizontal direction to determine a first encoding unit (1320) having a size of 2NxN. According to one embodiment, when the depth is determined based on the length of the longest side of the encoding unit, the depth of the encoding unit determined by splitting the first encoding unit (1300) having a size of 2Nx2N in the horizontal direction or the vertical direction may be the same as the depth of the first encoding unit (1300).

[0178] According to one embodiment, the width and height of the third coding unit (1314 or 1324) may be 1 / 4 times that of the first coding unit (1310 or 1320). When the depth of the first coding unit (1310 or 1320) is D, the depth of the second coding unit (1312 or 1322), which is 1 / 2 times the width and height of the first coding unit (1310 or 1320), may be D+1, and the depth of the third coding unit (1314 or 1324), which is 1 / 4 times the width and height of the first coding unit (1310 or 1320), may be D+2.

[0179] FIG. 14 illustrates an index (part index, hereinafter referred to as PID) for depth and encoding unit distinction that can be determined according to the shape and size of encoding units according to one embodiment.

[0180] According to one embodiment, the image decoding device (100) may split a first encoding unit (1400) having a square shape to determine second encoding units of various shapes. Referring to FIG. 14, the image decoding device (100) may split the first encoding unit (1400) in at least one of a vertical direction and a horizontal direction according to the split shape mode information to determine second encoding units (1402a, 1402b, 1404a, 1404b, 1406a, 1406b, 1406c, 1406d). That is, the image decoding device (100) can determine the second encoding unit (1402a, 1402b, 1404a, 1404b, 1406a, 1406b, 1406c, 1406d) based on the split shape mode information for the first encoding unit (1400).

[0181] According to one embodiment, the depth of the second coding units (1402a, 1402b, 1404a, 1404b, 1406a, 1406b, 1406c, 1406d) determined according to the split shape mode information for the first coding unit (1400) having a square shape may be determined based on the length of the long side. For example, since the length of one side of the first coding unit (1400) having a square shape and the length of the long side of the second coding unit (1402a, 1402b, 1404a, 1404b) having a non-square shape are the same, the depth of the first coding unit (1400) and the second coding units (1402a, 1402b, 1404a, 1404b) having a non-square shape may be considered to be the same as D. In contrast, when the image decoding device (100) divides the first encoding unit (1400) into four square-shaped second encoding units (1406a, 1406b, 1406c, 1406d) based on the split shape mode information, the length of one side of the square-shaped second encoding units (1406a, 1406b, 1406c, 1406d) is half the length of one side of the first encoding unit (1400), so the depth of the second encoding units (1406a, 1406b, 1406c, 1406d) may be a depth of D+1, which is one depth lower than D, the depth of the first encoding unit (1400).

[0182] According to one embodiment, the image decoding device (100) may split a first encoding unit (1410) having a height greater than its width into a plurality of second encoding units (1412a, 1412b, 1414a, 1414b, 1414c) in a horizontal direction according to the splitting shape mode information. According to one embodiment, the image decoding device (100) may split a first encoding unit (1420) having a width greater than its height into a plurality of second encoding units (1422a, 1422b, 1424a, 1424b, 1424c) in a vertical direction according to the splitting shape mode information.

[0183] According to one embodiment, the depth of the second coding unit (1412a, 1412b, 1414a, 1414b, 1414c. 1422a, 1422b, 1424a, 1424b, 1424c) determined based on the split shape mode information for the first coding unit (1410 or 1420) of a non-square shape may be determined based on the length of the long side. For example, since the length of one side of the second encoding unit (1412a, 1412b) in the shape of a square is half the length of one side of the first encoding unit (1410) in the shape of a non-square having a height longer than a width, the depth of the second encoding unit (1412a, 1412b) in the shape of a square is D+1, which is one depth lower than the depth D of the first encoding unit (1410) in the shape of a non-square.

[0184] Furthermore, the image decoding device (100) can split a non-square first encoding unit (1410) into an odd number of second encoding units (1414a, 1414b, 1414c) based on the split shape mode information. The odd number of second encoding units (1414a, 1414b, 1414c) can include non-square second encoding units (1414a, 1414c) and square second encoding units (1414b). In this case, since the length of the long side of the second encoding unit (1414a, 1414c) of a non-square shape and the length of one side of the second encoding unit (1414b) of a square shape are half the length of one side of the first encoding unit (1410), the depth of the second encoding unit (1414a, 1414b, 1414c) may be a depth of D+1, which is one depth lower than D, which is the depth of the first encoding unit (1410). The image decoding device (100) may determine the depth of the encoding units associated with the first encoding unit (1420) of a non-square shape, in which the width is longer than the height, in a manner corresponding to the above method of determining the depth of the encoding units associated with the first encoding unit (1410).

[0185] According to one embodiment, when determining an index (PID) for distinguishing divided coding units, the image decoding device (100) may determine the index based on a size ratio between the coding units when the coding units divided into an odd number are not of the same size. Referring to FIG. 14, among the coding units (1414a, 1414b, 1414c) divided into an odd number, the coding unit (1414b) located in the middle may have the same width as the other coding units (1414a, 1414c) but may have a height that is twice the height of the coding units (1414a, 1414c) that are different in height. That is, in this case, the coding unit (1414b) located in the middle may include two of the other coding units (1414a, 1414c). Accordingly, if the index (PID) of the encoding unit (1414b) located in the middle according to the scanning order is 1, the index of the encoding unit (1414c) located in the next order may be 3, which is an increase of 2. In other words, there may be a discontinuity in the index value. According to one embodiment, the image decoding device (100) may determine whether the encoding units divided into an odd number are not of the same size based on the presence or absence of discontinuity in the index for distinguishing between the divided encoding units.

[0186] According to one embodiment, the image decoding device (100) may determine whether the image is divided into a specific split shape based on the value of an index for distinguishing a plurality of coding units that are divided from the current coding unit. Referring to FIG. 14, the image decoding device (100) may divide a first coding unit (1410) having a rectangular shape in which the height is longer than the width, to determine an even number of coding units (1412a, 1412b) or an odd number of coding units (1414a, 1414b, 1414c). The image decoding device (100) may use an index (PID) indicating each coding unit to distinguish each of the plurality of coding units. According to one embodiment, the PID may be obtained from a sample (for example, an upper left sample) at a predetermined position of each coding unit.

[0187] According to one embodiment, the image decoding device (100) may determine an coding unit at a predetermined position among the coding units that are divided and determined using an index for distinguishing the coding units. According to one embodiment, when the split shape mode information for the first coding unit (1410) having a rectangular shape with a height longer than the width indicates that the first coding unit (1410) is divided into three coding units, the image decoding device (100) may divide the first coding unit (1410) into three coding units (1414a, 1414b, 1414c). The image decoding device (100) may assign an index to each of the three coding units (1414a, 1414b, 1414c). The image decoding device (100) may compare the indexes for each coding unit to determine the middle coding unit among the coding units divided into an odd number of coding units. The image decoding device (100) may determine a coding unit (1414b) having an index corresponding to a middle value among the indices of the coding units as a coding unit at a middle position among the coding units determined by splitting the first coding unit (1410). According to an embodiment, when determining an index for distinguishing the split coding units, the image decoding device (100) may determine the index based on a size ratio between the coding units when the coding units do not have the same size. Referring to FIG. 14, the coding unit (1414b) generated by splitting the first coding unit (1410) may have the same width as other coding units (1414a, 1414c) but may be twice the height of the coding units (1414a, 1414c) that are different in height. In this case, if the index (PID) of the encoding unit (1414b) located in the middle is 1, the index of the encoding unit (1414c) located in the next order may be 3, which is an increase of 2.In cases like this where the index increases uniformly and then the increase amount changes, the image decoding device (100) may determine that the current encoding unit is divided into a plurality of encoding units including encoding units having different sizes from other encoding units. According to one embodiment, when the split shape mode information indicates that the current encoding unit is divided into an odd number of encoding units, the image decoding device (100) may divide the current encoding unit into a form in which an encoding unit at a predetermined position among the odd number of encoding units (for example, a middle encoding unit) has a different size from the other encoding units. In this case, the image decoding device (100) may determine a middle encoding unit having a different size using an index (PID) for the encoding unit. However, the above-described index, the size or position of the encoding unit at the predetermined position to be determined are specific for explaining one embodiment and should not be interpreted as being limited thereto, and it should be interpreted that various indexes, positions and sizes of encoding units can be used.

[0188] According to one embodiment, the image decoding device (100) may utilize a predetermined data unit from which recursive division of the encoding unit begins.

[0189] FIG. 15 illustrates that a plurality of encoding units are determined according to a plurality of predetermined data units included in a picture according to one embodiment.

[0190] According to one embodiment, a predetermined data unit may be defined as a data unit from which a coding unit begins to be recursively split using split shape mode information. That is, it may correspond to a coding unit of the highest depth used in the process of determining multiple coding units for splitting the current picture. For convenience of explanation, this predetermined data unit will be referred to as a reference data unit hereinafter.

[0191] In one embodiment, the reference data unit may exhibit a predetermined size and shape. In one embodiment, the reference coding unit may include MxN samples, where M and N may be the same and may be integers expressed as powers of 2. That is, the reference data unit may exhibit a square or non-square shape, and may be subsequently divided into an integer number of coding units.

[0192] According to one embodiment, the video decoding device (100) can divide the current picture into a plurality of reference data units. According to one embodiment, the video decoding device (100) can divide the plurality of reference data units into which the current picture is divided using division type mode information for each reference data unit. This division process of the reference data units can correspond to a division process using a quad-tree structure.

[0193] According to one embodiment, the image decoding device (100) may predetermine the minimum size that a reference data unit included in the current picture may have. Accordingly, the image decoding device (100) may determine reference data units of various sizes having a size greater than or equal to the minimum size, and may determine at least one encoding unit using segmentation mode information based on the determined reference data unit.

[0194] Referring to FIG. 15, the image decoding device (100) may use a reference coding unit (1500) having a square shape, or may use a reference coding unit (1502) having a non-square shape. According to one embodiment, the shape and size of the reference coding unit may be determined according to various data units (e.g., sequence, picture, slice, slice segment, tile, tile group, maximum coding unit, etc.) that may include at least one reference coding unit.

[0195] According to one embodiment, the receiving unit (110) of the image decoding device (100) can obtain at least one of information on the shape of the reference coding unit and information on the size of the reference coding unit from the bitstream for each of the various data units. The process of determining at least one coding unit included in the square-shaped reference coding unit (1500) has been described above through the process of splitting the current coding unit (300) of FIG. 3, and the process of determining at least one coding unit included in the non-square-shaped reference coding unit (1502) has been described above through the process of splitting the current coding unit (400 or 450) of FIG. 4, so a detailed description thereof will be omitted.

[0196] According to one embodiment, the image decoding device (100) may use an index for identifying the size and shape of the reference coding unit to determine the size and shape of the reference coding unit according to some data units that are predetermined based on a predetermined condition. That is, the receiving unit (110) may obtain only an index for identifying the size and shape of the reference coding unit for each slice, slice segment, tile, tile group, maximum coding unit, etc., among the various data units (e.g., sequences, pictures, slices, slice segments, tiles, tile groups, maximum coding units, etc.) that satisfy a predetermined condition (e.g., data units having a size smaller than a slice) from the bitstream. The image decoding device (100) may determine the size and shape of the reference data unit for each data unit that satisfies the predetermined condition by using the index. When information about the shape of the reference coding unit and information about the size of the reference coding unit are obtained from the bitstream for each relatively small-sized data unit and used, the efficiency of the bitstream may not be good. Therefore, instead of directly obtaining information about the shape of the reference coding unit and information about the size of the reference coding unit, only the index may be obtained and used. In this case, at least one of the size and shape of the reference coding unit corresponding to the index indicating the size and shape of the reference coding unit may be determined in advance. That is, the image decoding device (100) can determine at least one of the size and shape of the reference coding unit included in the data unit that serves as the basis for obtaining the index by selecting at least one of the sizes and shapes of the predetermined reference coding units according to the index.

[0197] According to one embodiment, the image decoding device (100) may use at least one reference coding unit included in one maximum coding unit. That is, a maximum coding unit for dividing an image may include at least one reference coding unit, and a coding unit may be determined through a recursive splitting process of each reference coding unit. According to one embodiment, at least one of the width and the height of the maximum coding unit may correspond to an integer multiple of at least one of the width and the height of the reference coding unit. According to one embodiment, the size of the reference coding unit may be a size obtained by splitting the maximum coding unit n times according to a quad tree structure. That is, the image decoding device (100) may split the maximum coding unit n times according to the quad tree structure to determine the reference coding unit, and may split the reference coding unit based on at least one of block shape information and split shape mode information according to various embodiments.

[0198] FIG. 16 illustrates a processing block that serves as a criterion for determining the order of determination of reference coding units included in a picture according to one embodiment.

[0199] According to one embodiment, the image decoding apparatus (100) may determine at least one processing block for dividing a picture. The processing block is a data unit including at least one reference coding unit for dividing an image, and at least one reference coding unit included in the processing block may be determined in a specific order. That is, the determination order of at least one reference coding unit determined in each processing block may correspond to one of various types of orders in which the reference coding unit may be determined, and the determination order of the reference coding unit determined in each processing block may be different for each processing block. The determination order of the reference coding unit determined for each processing block may be one of various orders such as raster scan, Z-scan, N-scan, up-right diagonal scan, horizontal scan, and vertical scan, but the order in which it may be determined should not be interpreted as being limited to the above scan orders.

[0200] According to one embodiment, the image decoding device (100) can obtain information about the size of a processing block to determine the size of at least one processing block included in an image. The image decoding device (100) can obtain information about the size of a processing block from a bitstream to determine the size of at least one processing block included in an image. The size of the processing block may be a predetermined size of a data unit indicated by the information about the size of the processing block.

[0201] According to one embodiment, the receiving unit (110) of the image decoding device (100) can obtain information about the size of a processing block from a bitstream for each specific data unit. For example, the information about the size of a processing block can be obtained from the bitstream for each data unit such as an image, a sequence, a picture, a slice, a slice segment, a tile, a tile group, etc. That is, the receiving unit (110) can obtain information about the size of a processing block from the bitstream for each of the above-described multiple data units, and the image decoding device (100) can determine the size of at least one processing block for dividing a picture using the obtained information about the size of the processing block, and the size of the processing block can be an integer multiple of a reference coding unit.

[0202] According to one embodiment, the image decoding device (100) may determine the size of the processing block (1602, 1612) included in the picture (1600). For example, the image decoding device (100) may determine the size of the processing block based on information about the size of the processing block obtained from the bitstream. Referring to FIG. 16, the image decoding device (100) may determine the horizontal size of the processing block (1602, 1612) to be four times the horizontal size of the reference coding unit, and the vertical size of the processing block (1602, 1612) to be four times the vertical size of the reference coding unit, according to one embodiment. The image decoding device (100) may determine the order in which at least one reference coding unit is determined within at least one processing block.

[0203] According to one embodiment, the video decoding device (100) may determine each processing block (1602, 1612) included in the picture (1600) based on the size of the processing block, and may determine the determination order of at least one reference coding unit included in the processing block (1602, 1612). According to one embodiment, the determination of the reference coding unit may include determining the size of the reference coding unit.

[0204] According to one embodiment, the image decoding device (100) can obtain information about a determination order of at least one reference coding unit included in at least one processing block from a bitstream, and can determine an order in which at least one reference coding unit is determined based on the obtained information about the determination order. The information about the determination order can be defined as an order or direction in which the reference coding units are determined within the processing block. That is, the order in which the reference coding units are determined can be independently determined for each processing block.

[0205] According to one embodiment, the image decoding device (100) can obtain information about the determination order of the reference coding unit for each specific data unit from the bitstream. For example, the receiving unit (110) can obtain information about the determination order of the reference coding unit for each data unit such as an image, sequence, picture, slice, slice segment, tile, tile group, processing block, etc. from the bitstream. Since the information about the determination order of the reference coding unit indicates the determination order of the reference coding unit within the processing block, the information about the determination order can be obtained for each specific data unit including an integer number of processing blocks.

[0206] The image decoding device (100) can determine at least one reference encoding unit based on an order determined according to one embodiment.

[0207] According to one embodiment, the receiver (110) may obtain information about the reference coding unit determination order as information related to the processing blocks (1602, 1612) from the bitstream, and the image decoding device (100) may determine the order in which at least one reference coding unit included in the processing blocks (1602, 1612) is determined and at least one reference coding unit included in the picture (1600) may be determined according to the determination order of the coding units. Referring to FIG. 16, the image decoding device (100) may determine the determination order (1604, 1614) of at least one reference coding unit related to each processing block (1602, 1612). For example, when information about the determination order of the reference coding unit is obtained for each processing block, the determination order of the reference coding unit related to each processing block (1602, 1612) may be different for each processing block. If the reference encoding unit determination order (1604) related to the processing block (1602) is a raster scan order, the reference encoding unit included in the processing block (1602) can be determined according to the raster scan order. In contrast, if the reference encoding unit determination order (1614) related to another processing block (1612) is a reverse order of the raster scan order, the reference encoding unit included in the processing block (1612) can be determined according to the reverse order of the raster scan order.

[0208] According to one embodiment, the image decoding device (100) can decode at least one determined reference coding unit. The image decoding device (100) can decode an image based on the determined reference coding unit through the above-described embodiment. The method of decoding the reference coding unit may include various methods of decoding an image.

[0209] According to one embodiment, the video decoding device (100) may obtain and use block shape information indicating the shape of the current encoding unit or split shape mode information indicating a method of splitting the current encoding unit from the bitstream. The split shape mode information may be included in a bitstream related to various data units. For example, the video decoding device (100) may use split shape mode information included in a sequence parameter set, a picture parameter set, a video parameter set, a slice header, a slice segment header, a tile header, and a tile group header. Furthermore, the video decoding device (100) may obtain and use a syntax element corresponding to block shape information or split shape mode information from the bitstream for each maximum encoding unit, each reference encoding unit, and each processing block.

[0210] Hereinafter, a method for determining a partitioning rule according to one embodiment of the present disclosure will be described in detail.

[0211] The video decoding device (100) can determine a segmentation rule of the video. The segmentation rule may be predetermined between the video decoding device (100) and the video encoding device (2200). The video decoding device (100) can determine the segmentation rule of the video based on information obtained from a bitstream. The video decoding device (100) can determine the segmentation rule based on information obtained from at least one of a sequence parameter set, a picture parameter set, a video parameter set, a slice header, a slice segment header, a tile header, and a tile group header. The video decoding device (100) can determine the segmentation rule differently according to a frame, a slice, a tile, a temporal layer, a maximum coding unit, or an coding unit.

[0212] The image decoding device (100) can determine a segmentation rule based on the block shape of the encoding unit. The block shape can include the size, shape, width and height ratio, and direction of the encoding unit. The image encoding device (2200) and the image decoding device (100) can determine in advance that the segmentation rule will be determined based on the block shape of the encoding unit. However, the present invention is not limited thereto. The image decoding device (100) can determine the segmentation rule based on information obtained from the bitstream received from the image encoding device (2200).

[0213] The shape of the encoding unit may include a square and a non-square. If the width and height of the encoding unit are equal, the image decoding device (100) may determine the shape of the encoding unit as a square. In addition, if the width and height of the encoding unit are not equal, the image decoding device (100) may determine the shape of the encoding unit as a non-square.

[0214] The size of the coding unit may include various sizes such as 4x4, 8x4, 4x8, 8x8, 16x4, 16x8, ..., 256x256. The size of the coding unit may be classified according to the length of the long side, the length of the short side, or the area of ​​the coding unit. The image decoding device (100) may apply the same splitting rule to the coding units classified into the same group. For example, the image decoding device (100) may classify the coding units having the same long side length into the same size. In addition, the image decoding device (100) may apply the same splitting rule to the coding units having the same long side length.

[0215] The ratio of the width to the height of the coding unit may include 1:2, 2:1, 1:4, 4:1, 1:8, 8:1, 1:16, 16:1, 32:1, or 1:32, etc. In addition, the direction of the coding unit may include a horizontal direction and a vertical direction. The horizontal direction may indicate a case where the length of the width of the coding unit is longer than the length of the height. The vertical direction may indicate a case where the length of the width of the coding unit is shorter than the length of the height.

[0216] The image decoding device (100) can adaptively determine a splitting rule based on the size of the encoding unit. The image decoding device (100) can determine a different allowable splitting mode based on the size of the encoding unit. For example, the image decoding device (100) can determine whether splitting is allowed based on the size of the encoding unit. The image decoding device (100) can determine a splitting direction based on the size of the encoding unit. The image decoding device (100) can determine an allowable splitting type based on the size of the encoding unit.

[0217] Determining the splitting rule based on the size of the encoding unit may be a splitting rule predetermined between the image encoding device (2200) and the image decoding device (100). In addition, the image decoding device (100) may determine the splitting rule based on information obtained from the bitstream.

[0218] The image decoding device (100) can adaptively determine a segmentation rule based on the position of the encoding unit. The image decoding device (100) can adaptively determine a segmentation rule based on the position that the encoding unit occupies in the image.

[0219] Additionally, the image decoding device (100) can determine a splitting rule so that encoding units generated through different splitting paths do not have the same block shape. However, this is not limited thereto, and encoding units generated through different splitting paths may have the same block shape. Encoding units generated through different splitting paths may have different decoding processing orders. Since the decoding processing order has been described together with FIG. 12, a detailed description thereof will be omitted.

[0220] Hereinafter, with reference to FIGS. 17 to 20, a method and apparatus for encoding or decoding a video are described, wherein the method determines whether a current block touches an upper boundary line of a maximum coding unit including the current block, and if the current block is determined to touch the upper boundary line of the maximum coding unit, the upper reference line of the current block is determined as one reference line, and if the current block is determined not to touch the upper boundary line of the maximum coding unit, the upper reference line of the current block is determined based on N reference lines, and a prediction is performed on the current block based on the determined upper reference line.

[0221] FIG. 17 illustrates a block diagram of a video encoding device according to one embodiment.

[0222] A video encoding device (1700) according to one embodiment may include a memory (1710) and at least one processor (1720) connected to the memory (1710). Operations of the video encoding device (1700) according to one embodiment may operate as individual processors or may be operated under the control of a central processor. In addition, the memory (1710) of the video encoding device (1700) may store data received from the outside and data generated by the processor, for example, information on an upper reference line of a current block.

[0223] The processor (1720) of the video encoding device (1700) determines whether a current block touches an upper boundary line of a maximum coding unit including the current block, and if it is determined that the current block touches the upper boundary line of the maximum coding unit, it determines an upper reference line of the current block as one reference line, and if it is determined that the current block does not touch the upper boundary line of the maximum coding unit, it determines an upper reference line of the current block based on N reference lines, and it can perform prediction on the current block based on the determined upper reference line.

[0224] Hereinafter, with reference to FIG. 18, a video encoding device (1700) according to an embodiment determines whether a current block touches an upper boundary line of a maximum coding unit including the current block, and if it is determined that the current block touches the upper boundary line of the maximum coding unit, an upper reference line of the current block is determined as one reference line, and if it is determined that the current block does not touch the upper boundary line of the maximum coding unit, an upper reference line of the current block is determined based on N reference lines, and a video encoding method for performing prediction on the current block based on the determined upper reference line will be described in detail.

[0225] FIG. 18 illustrates a flowchart of a video encoding method according to one embodiment.

[0226] Referring to FIG. 18, in step s1810, the video encoding device (1700) can determine whether the current block is adjacent to the upper boundary of the maximum encoding unit including the current block.

[0227] In step s1830, if it is determined that the current block is in contact with the upper boundary line of the maximum encoding unit, the video encoding device (1700) may determine the upper reference line of the current block as one reference line.

[0228] In one embodiment, one reference line may be a reference line that touches the upper side of the current block.

[0229] In step s1850, if it is determined that the current block does not touch the upper boundary line of the maximum encoding unit, the video encoding device (1700) may determine the upper reference line of the current block based on N reference lines. Here, N is a natural number.

[0230] According to one embodiment, the video encoding device (1700) may generate reference line information indicating the value of N.

[0231] According to one embodiment, if it is determined that the current block touches the upper boundary line of the maximum encoding unit, reference line information may not be generated.

[0232] According to one embodiment, the value of N may be determined through a SATD (Sum of Transform Difference) or RDO (Rate Distortion Optimization) calculation, so that reference line information representing N may be encoded.

[0233] According to one embodiment, if it is determined that the current block does not touch the upper boundary line of the maximum encoding unit, and if N is 1, the upper reference line may be determined as a first reference line touching the upper side of the current block.

[0234] According to one embodiment, if it is determined that the current block does not touch the upper boundary line of the maximum encoding unit, and if N is 2, the upper reference line may include a first reference line touching the upper side of the current block and a second reference line touching the upper side of the first reference line.

[0235] In another embodiment, if it is determined that the current block does not touch the upper boundary line of the maximum encoding unit, and if N is 2, the upper reference line may be determined as a second reference line touching the upper side of the first reference line touching the upper side of the current block. That is, if N is 2, the reference line located second above the current block may be determined as the upper reference line.

[0236] According to one embodiment, if it is determined that the current block does not touch the upper boundary line of the maximum encoding unit, and if N is 3, the upper reference line may include a first reference line touching the upper side of the current block, a second reference line touching the upper side of the first reference line, and a fourth reference line touching the upper side of a third reference line touching the upper side of the second reference line.

[0237] In another embodiment, if it is determined that the current block does not touch the upper boundary line of the maximum encoding unit, and if N is 3, the upper reference line may be determined as a fourth reference line touching the upper side of a third reference line touching the upper side of a second reference line touching the upper side of a first reference line touching the upper side of the current block. That is, if N is 3, the reference line located fourth above the current block may be determined as the upper reference line.

[0238] In one embodiment, the left reference line located to the left of the current block may be determined based on N reference lines located to the left of the current block.

[0239] In step s1870, the video encoding device (1700) can perform prediction for the current block based on the determined upper reference line.

[0240] According to one embodiment, a prediction for the current block may be performed using a left reference line determined based on the determined upper reference line and N reference lines located to the left of the current block.

[0241] FIG. 19 and FIG. 20 illustrate a block diagram of a video decoding device according to an embodiment corresponding to the video encoding device and video encoding method described above, respectively, and a flowchart of a video decoding method according to an embodiment.

[0242] FIG. 19 illustrates a block diagram of a video decoding device according to one embodiment.

[0243] A video decoding device (1900) according to one embodiment may include a memory (1910) and at least one processor (1920) connected to the memory (1910). Operations of the video decoding device (1900) according to one embodiment may operate as individual processors or may be operated under the control of a central processor. In addition, the memory (1910) of the video decoding device (1900) may store data received from an external source and data generated by the processor, for example, information on an upper reference line of a current block.

[0244] The processor (1920) of the video decoding device (1900) determines whether a current block touches an upper boundary line of a maximum coding unit including the current block, and if it is determined that the current block touches the upper boundary line of the maximum coding unit, determines an upper reference line of the current block as one reference line, and if it is determined that the current block does not touch the upper boundary line of the maximum coding unit, determines an upper reference line of the current block based on N reference lines, and performs prediction on the current block based on the determined upper reference line.

[0245] Hereinafter, with reference to FIG. 20, a video decoding device (1900) according to an embodiment determines whether a current block touches an upper boundary line of a maximum coding unit including the current block, and if it is determined that the current block touches the upper boundary line of the maximum coding unit, an upper reference line of the current block is determined as one reference line, and if it is determined that the current block does not touch the upper boundary line of the maximum coding unit, an upper reference line of the current block is determined based on N reference lines, and a video decoding method for performing prediction on the current block based on the determined upper reference line will be described in detail.

[0246] FIG. 20 illustrates a flowchart of a video decoding method according to one embodiment.

[0247] Referring to FIG. 20, in step s2010, the video decoding device (1900) can determine whether the current block is adjacent to the upper boundary of the maximum encoding unit including the current block.

[0248] In step s2030, if it is determined that the current block is adjacent to the upper boundary line of the maximum encoding unit, the video decoding device (1900) may determine the upper reference line of the current block as one reference line.

[0249] In step s2050, if it is determined that the current block does not touch the upper boundary line of the maximum encoding unit, the video decoding device (1900) may determine the upper reference line of the current block based on N reference lines.

[0250] In one embodiment, N may be determined by reference line information obtained from the bitstream.

[0251] According to one embodiment, if it is determined that the current block touches the upper boundary line of the maximum encoding unit, the reference line information may not be acquired.

[0252] According to one embodiment, if it is determined that the current block does not touch the upper boundary line of the maximum encoding unit, and if N is 1, the upper reference line may be determined as a first reference line touching the upper side of the current block.

[0253] According to one embodiment, if it is determined that the current block does not touch the upper boundary line of the maximum encoding unit, and if N is 2, the upper reference line may include a first reference line touching the upper side of the current block and a second reference line touching the upper side of the first reference line.

[0254] In another embodiment, if it is determined that the current block does not touch the upper boundary line of the maximum encoding unit, and if N is 2, the upper reference line may be determined as a second reference line touching the upper side of the first reference line touching the upper side of the current block. That is, if N is 2, the reference line located second above the current block may be determined as the upper reference line.

[0255] According to one embodiment, if it is determined that the current block does not touch the upper boundary line of the maximum encoding unit, and if N is 3, the upper reference line may include a first reference line touching the upper side of the current block, a second reference line touching the upper side of the first reference line, and a fourth reference line touching the upper side of a third reference line touching the upper side of the second reference line.

[0256] In another embodiment, if it is determined that the current block does not touch the upper boundary line of the maximum encoding unit, and if N is 3, the upper reference line may be determined as a fourth reference line touching the upper side of a third reference line touching the upper side of a second reference line touching the upper side of a first reference line touching the upper side of the current block. That is, if N is 3, the reference line located fourth above the current block may be determined as the upper reference line.

[0257] In one embodiment, the left reference line located to the left of the current block may be determined based on N reference lines located to the left of the current block.

[0258] In step s2070, the video decoding device (1900) can perform prediction for the current block based on the determined upper reference line.

[0259] According to one embodiment, a prediction for the current block may be performed using a left reference line determined based on the determined upper reference line and N reference lines located to the left of the current block.

[0260] In one embodiment, if there is a reference sample without a sample value within the upper reference line, the reference sample without a sample value within the upper reference line may be padded using a predetermined default value. That is, the sample value of the reference sample without a sample value within the upper reference line may be determined as a predetermined default value.

[0261] In one embodiment, if there is a reference sample without a sample value within the upper reference line, the reference sample value having a sample value within the upper reference line may be padded with the reference sample without a sample value within the upper reference line. That is, the sample value of the reference sample without a sample value within the upper reference line may be determined as the reference sample value having a sample value within the upper reference line.

[0262] In one embodiment, if there is a reference sample without a sample value within the upper reference line, the reference sample without a sample value within the upper reference line can be regenerated using a reference sample value having a sample value within the upper reference line.

[0263] In one embodiment, if there is a reference line without a sample value in the upper reference line, the sample value of the reference line without a sample value may be padded using a predetermined default value. That is, the sample value of the reference line without a sample value may be determined as a predetermined default value.

[0264] In one embodiment, if there is a reference line without a sample value in the upper reference line, the reference sample value having a sample value may be padded with the reference sample without a sample value. That is, the sample value of the reference line without a sample value may be determined as the sample value of the reference line with a sample value.

[0265] In one embodiment, if there is a reference line without a sample value in the upper reference line, the sample of the reference line without a sample value can be regenerated using the sample value of the reference line having a sample value.

[0266] By using a single reference line when the current block touches the upper boundary of the largest coding unit that includes the current block, the problem of an increase in the reference line buffer amount that occurs when using multiple reference lines is solved. Specifically, when multiple reference lines are stored and used in the reference line buffer, when the current block touches the upper boundary of the largest coding unit that includes the current block, only the single reference line closest to the upper boundary is stored, thereby reducing the buffer amount in terms of the largest coding unit. For example, even if prediction is performed using only one of the multiple reference lines, all of the multiple reference lines must be stored in order to determine which line of the multiple reference lines to use. However, when the prediction is performed using the upper boundary, only the single reference line touching the upper boundary is stored and used, thereby reducing the buffer amount in terms of the largest coding unit.

[0267] According to one embodiment, a method of determining a reference line based on N upper reference lines when the current block touches the upper boundary of the maximum coding unit containing the current block and using one upper reference line when the current block does not touch the upper boundary of the maximum coding unit is described below with reference to FIG. 21.

[0268] FIG. 21 is a drawing for explaining a method of using at least one reference line according to one embodiment.

[0269] Referring to FIG. 21, in the case of multi-reference line prediction using at least one reference line, reference lines (2121, 2131, 2141, 2151) located above the current block (2110) and reference lines (2122, 2132, 2142, 2152) located to the left of the current block (2110) can be used. Specifically, the reference lines located on the upper side include a first upper reference line (2121) that contacts the upper side of the current block (2110), a second upper reference line (2131) that contacts the upper side of the first upper reference line (2121), a third upper reference line (2141) that contacts the upper side of the second upper reference line (2131), and a fourth upper reference line (2151) that contacts the upper side of the third upper reference line (2141), and the reference lines located on the left side include a first left reference line (2122) that contacts the left side of the current block (2110), a second left reference line (2132) that contacts the left side of the first left reference line (2122), a third left reference line (2142) that contacts the left side of the second left reference line (2132), and a fourth left reference line (2151) that contacts the left side of the third left reference line (2142). It may include line (2152).

[0270] Additionally, in multi-reference line prediction, the third upper reference line (2141) and the third left reference line (2142) may not be used. Specifically, since multi-reference line prediction checks samples at various locations and uses the most efficient reference sample, the third reference line is not used, and at least one of the first, second, and fourth reference lines may be used.

[0271] The following examples related to Fig. 21 are described as having N reference lines available on each of the upper and left sides of the current block. Here, the term "available" does not refer to the presence or absence of a reference line, but rather to the usability of the reference line in the algorithm used for prediction.

[0272] Hereinafter, in this specification, “MRL index” is an index indicating one reference line used in prediction of a current block among multiple reference lines used in multiple reference line prediction.

[0273] In one embodiment, when N is 1 (MRL index = 0), the first upper reference line (2121) that borders the upper side of the current block and the first left reference line (2122) that borders the left side of the current block may be used for prediction of the current block. That is, when the "MRL index" is 0, the first upper reference line (2121) and the first left reference line (2122), which are the first reference lines of the upper reference line and the left reference line of the current block, may be used.

[0274] In one embodiment, when N is 2, in prediction for the current block, a first upper reference line (2121) that touches the upper side of the current block, a second upper reference line (2131) that touches the upper side of the first upper reference line (2121), a first left reference line (2122) that touches the left side of the current block, and a second left reference line (2132) that touches the left side of the first left reference line (2122) may be used.

[0275] In another embodiment, when N is 2 (MRL index = 1), for prediction of the current block, the second upper reference line (2131) that borders the upper side of the current block and the second left reference line (2132) that borders the left side of the current block may be used. That is, when the "MRL index" is 1, the second upper reference line (2131) and the second left reference line (2132), which are the second reference lines of the upper reference line and the left reference line of the current block, may be used.

[0276] In one embodiment, when N is 3, in prediction for the current block, a first upper reference line (2121) that contacts the upper side of the current block, a second upper reference line (2131) that contacts the upper side of the first upper reference line (2131), a fourth upper reference line (2151) that contacts the upper side of a third upper reference line (2141) that contacts the upper side of the second upper reference line (2131), a first left reference line (2122) that contacts the left side of the current block, a second left reference line (2132) that contacts the left side of the first left reference line (2122), and a fourth left reference line (2152) that contacts the left side of a third left reference line (2142) that contacts the left side of the second left reference line (2132) may be used. That is, three upper reference lines, namely, the first upper reference line (2121), the second upper reference line (2131), and the fourth upper reference line (2151), and three left reference lines, namely, the first left reference line (2122), the second left reference line (2132), and the fourth left reference line (2152), can be used.

[0277] In another embodiment, when N is 3 (MRL index = 2), the fourth upper reference line (2151) that borders the upper side of the current block and the fourth left reference line (2152) that borders the left side of the current block may be used for prediction of the current block. That is, when the "MRL index" is 2, the fourth upper reference line (2151) and the fourth left reference line (2152), which are the fourth reference lines of the upper reference line and the left reference line of the current block, may be used.

[0278] According to one embodiment, when the current block touches the upper boundary of the largest coding unit containing the current block and N is 1 (MRL index = 0), a first upper reference line (2121) on the upper side of the current block (2110) and a first left reference line (2122) on the left side of the current block may be used for prediction of the current block.

[0279] According to one embodiment, when the current block is adjacent to the upper boundary of the largest coding unit containing the current block and N is 2, a first upper reference line (2121) above the current block (2110) and a first left reference line (2122) and a second left reference line (2132) on the left side of the current block may be used for prediction of the current block.

[0280] According to another embodiment, when the current block touches the upper boundary of the maximum coding unit including the current block and N is 2 (MRL index = 1), the first upper reference line (2121) above the current block (2110) and the second left reference line (2132) of the current block may be used for prediction of the current block. According to one embodiment, when the current block touches the upper boundary of the maximum coding unit including the current block and N is 3, the first upper reference line (2121) above the current block (2110) and the first left reference line (2122), the second left reference line (2132), and the fourth left reference line (2152) on the left side of the current block may be used for prediction of the current block.

[0281] According to another embodiment, when the current block touches the upper boundary of the largest coding unit containing the current block and N is 3 (MRL index = 2), the first upper reference line (2121) above the current block (2110) and the fourth left reference line (2152) on the left side of the current block may be used for prediction of the current block.

[0282] According to one embodiment, on the encoding side, N may be determined through SATD or RDO calculation, and reference line information representing N may be signaled.

[0283] According to one embodiment, on the encoding side, if the current block touches the upper boundary of the largest encoding unit containing the current block, reference line information indicating N may not be generated.

[0284] In one embodiment, at the decryption side, N can be determined via reference line information representing the signaled N.

[0285] According to one embodiment, on the decoding side, if the current block touches the upper boundary of the largest coding unit containing the current block, reference line information indicating N may not be acquired.

[0286] FIG. 22 illustrates a flowchart of a video encoding method according to another embodiment.

[0287] The video encoding device (1700) of FIG. 17 can perform an operation according to the video encoding method of FIG. 22.

[0288] The video encoding device (1700) may include a memory (1710) and at least one processor (1720) connected to the memory (1710). The operations of the video encoding device (1700) according to one embodiment may operate as an individual processor or may be operated under the control of a central processor. In addition, the memory (1710) of the video encoding device (1700) may store data received from the outside and data generated by the processor, for example, information on an upper reference line of a current luma block.

[0289] The processor (1720) of the video encoding device (1700) determines whether a current luma block touches an upper boundary of a maximum coding unit including the current luma block, and if it is determined that the current luma block touches the upper boundary of the maximum coding unit, the processor determines an upper reference line of the current luma block as one reference line, and if it is determined that the current luma block does not touch the upper boundary of the maximum coding unit, the processor determines an upper reference line of the current luma block as two reference lines, and performs prediction on a current chroma block corresponding to the current luma block based on the determined upper reference lines.

[0290] Referring to FIG. 22, in step s2210, the video encoding device (1700) can determine whether the current luma block is adjacent to the upper boundary of the maximum encoding unit including the current luma block.

[0291] In step s2230, if it is determined that the current luma block is in contact with the upper boundary line of the maximum encoding unit, the video encoding device (1700) may determine the upper reference line of the current luma block as one reference line.

[0292] In step s2250, if it is determined that the current luma block does not touch the upper boundary of the maximum encoding unit, the video encoding device (1700) may determine the upper reference line of the current luma block as two reference lines.

[0293] In one embodiment, the two upper reference lines may include a first reference line that contacts the upper side of the current block and a second reference line that contacts the upper side of the first reference line.

[0294] In step s2270, the video encoding device (1700) can perform prediction for the current chroma block corresponding to the current luma block based on the determined upper reference line.

[0295] In one embodiment, prediction for a current chroma block corresponding to a current luma block can be performed based on a determined upper reference line and two left reference lines.

[0296] According to one embodiment, weight information and deviation information are determined using a relationship between luma reference samples of the current luma block included in the upper reference line and chroma reference samples bordering the upper side of the current chroma block, and prediction for the current chroma block can be performed by determining the current chroma block based on the weight information, the deviation information, and the luma samples of the current luma block.

[0297] FIG. 23 illustrates a flowchart of a video decoding method according to another embodiment.

[0298] The video encoding device (1900) of FIG. 19 can perform an operation according to the video encoding method of FIG. 23.

[0299] The video encoding device (1900) may include a memory (1910) and at least one processor (1920) connected to the memory (1910). The operations of the video encoding device (1900) according to one embodiment may operate as an individual processor or may be operated under the control of a central processor. In addition, the memory (1910) of the video encoding device (1900) may store data received from the outside and data generated by the processor, for example, information on an upper reference line of a current luma block.

[0300] The processor (1920) of the video encoding device (1900) determines whether a current luma block touches an upper boundary of a maximum coding unit including the current luma block, and if it is determined that the current luma block touches the upper boundary of the maximum coding unit, the processor determines an upper reference line of the current luma block as one reference line, and if it is determined that the current luma block does not touch the upper boundary of the maximum coding unit, the processor determines an upper reference line of the current luma block as two reference lines, and performs prediction on a current chroma block corresponding to the current luma block based on the determined upper reference lines.

[0301] Referring to FIG. 23, in step s2310, the video decoding device (1900) can determine whether the current luma block is adjacent to the upper boundary of the maximum encoding unit including the current luma block.

[0302] In step s2330, if it is determined that the current luma block is adjacent to the upper boundary line of the maximum encoding unit, the video decoding device (1900) may determine the upper reference line of the current luma block as one reference line.

[0303] In step s2350, if it is determined that the current luma block does not touch the upper boundary of the maximum encoding unit, the video decoding device (1900) may determine the upper reference line of the current luma block as two reference lines.

[0304] In one embodiment, the two upper reference lines may include a first reference line that touches the upper side of the current luma block and a second reference line that touches the upper side of the first reference line.

[0305] In step s2370, the video decoding device (1900) can perform prediction for the current chroma block corresponding to the current luma block based on the determined upper reference line.

[0306] In one embodiment, prediction for a current chroma block corresponding to a current luma block can be performed based on a determined upper reference line and two left reference lines.

[0307] According to one embodiment, weight information and deviation information are determined using a relationship between luma reference samples of the current luma block included in the upper reference line and chroma reference samples bordering the upper side of the current chroma block, and prediction for the current chroma block can be performed by determining the current chroma block based on the weight information, the deviation information, and the luma samples of the current luma block.

[0308] A method of performing prediction for the current chroma block by utilizing the relationship between the luma reference sample of the current luma block and the chroma reference sample of the current chroma block is described below with reference to FIGS. 24a to 25b.

[0309] FIG. 24a illustrates luma samples located around a current luma block and chroma samples located around a current chroma block according to one embodiment, and FIG. 24b illustrates luma samples of a current luma block and chroma samples of a current chroma block according to one embodiment.

[0310] Referring to FIGS. 24a and 24b, weight information and deviation information regarding the correlation between six luma samples L1 to L6 (2450) among the restored luma samples (2430) neighboring the current luma block (2470) among the luma block (2410) and the chroma sample (2460) among the restored chroma samples (2440) neighboring the current chroma block (2480) among the chroma blocks (2420) can be derived, and the weight information, deviation information, and the restored luma samples L1 to L6 (2490) of the current luma block (2470) derived in the same manner as in Equation 1 can be used to derive the chroma sample of the current chroma block (2480). (2491) can be restored.

[0311] According to one embodiment, one or more chroma samples may be predicted using N predetermined luma samples to predict the chroma sample. In addition, the N luma samples may be a luma sample of a current luma block corresponding to a position of a chroma sample of a current chroma block and surrounding samples of the corresponding luma sample of the current luma block, or any non-adjacent samples of the luma sample of the current luma block corresponding to a position of a chroma sample of the current chroma block and the corresponding luma sample of the current luma block.

[0312] Specifically, the predictor of chroma samples ( ) can be expressed as in mathematical expression 1 or 2.

[0313]

[0314]

[0315] As in mathematical expressions 1 and 2, the predictor of the chroma sample ( ) represents the value obtained by adding the deviation value to the weighted sum of the sample values ​​of luma samples (e.g., L1) or the difference values ​​(e.g., ΔL1) between the luma samples and the mean value of the luma samples and the weights (e.g., ω1) corresponding to each.

[0316] In one embodiment, the weights ω1 to ω N Some of the values ​​may be 0.

[0317] According to one embodiment, a prediction mode of a surrounding luma block of a current luma block is an intra prediction mode, weight information is a modeling parameter value indicating a correlation between a luma sample of a surrounding luma block and a chroma sample of a surrounding chroma block, a chroma sample of a current chroma block is reconstructed using six luma samples among reconstructed luma samples of the current luma block, six weight values ​​respectively corresponding to the six luma samples, and one deviation value among the deviation information, and the six weights may be values ​​generated by multiplying a predetermined fixed weight according to the intra prediction mode by a modeling parameter value indicating a correlation between a luma sample and a chroma sample.

[0318] When IP is the intra prediction mode, the modeling parameters are ω1,…, ω N s·ω´ respectively ip,1 ,…, s·ω´ ip,N can be replaced by ω´ depending on the intra prediction mode. ip,1 ,…, ω´ ip,N By fixing it to , only the modeling parameters s and μ can be used.

[0319] According to one embodiment, a fixed weight ω´ depending on the intra prediction mode ip,1 ,…, ω´ ip,N The value may be the same regardless of the intra prediction mode, or the value may be different depending on the intra prediction mode, in the form of a Gaussian filter, etc.

[0320] FIG. 25a illustrates luma samples located around a current luma block and chroma samples located around a current chroma block according to another embodiment, and FIG. 25b illustrates luma samples of a current luma block and chroma samples of a current chroma block according to another embodiment.

[0321] Referring to FIGS. 25a and 25b, when the current luma block touches the upper boundary of the largest coding unit containing the current luma block, one reference line touching the upper side of the current luma block is used.

[0322] Specifically, among the restored luma samples (2530) neighboring the current luma block (2570) among the luma block (2510), three luma samples L'1 to L'3 (2550) included in one reference line that touches the upper side of the current luma block and among the restored chroma samples (2540) neighboring the current chroma block (2580) among the chroma blocks (2520), weight information and deviation information for the correlation can be derived, and the weight information, deviation information, and the restored luma samples L'1 to L'3 (2590) of the current luma block (2570) derived in the same manner as in mathematical expression 1 can be used to derive the chroma sample of the current chroma block (2580). (2591) can be restored.

[0323] In addition, since the reference line touching the left side of the current luma block uses two reference lines as they are, weight information and deviation information for the correlation between the six surrounding luma samples and the surrounding chroma samples are derived, as in FIGS. 24a and 24b, and the chroma samples of the current chroma block (2480) are used to derive the restored luma samples L1 to L6 (2490) of the current luma block. (2491) can be restored.

[0324] In one embodiment, when the current luma block touches the upper boundary of the largest coding unit containing the current luma block, the number and positions of samples used to predict the chroma block from the luma block may be changed according to the algorithm, provided that one reference line touching the upper side of the current luma block is used.

[0325] Additionally, even if the current luma block does not touch the upper boundary of the largest coding unit containing the current luma block, the number and positions of samples used to predict the chroma block from the luma block may change depending on the algorithm.

[0326] FIG. 26a illustrates an embodiment in which the number of upper reference lines and left reference lines is different, FIG. 26b illustrates an embodiment in which the number of upper reference lines and left reference lines is the same, and FIG. 26c illustrates an embodiment in which the number of upper reference lines and left reference lines is different, and the two reference lines are padded to be the same.

[0327] Referring to FIG. 26a, according to one embodiment, the number of upper reference lines (2620) and left reference lines (2630) of the current block (2610) may be different. Specifically, the number of upper reference lines (2620) located on the upper side of the current block (2610) is determined as N, and the number of left reference lines (2630) located on the left side of the current block (2610) is determined as M, and M≥N. N may be determined as the value of the maximum line buffer set in the codec. For example, N=2, M=4, N=1, M=2, or N=1, M=4.

[0328] According to one embodiment, referring to FIG. 26a, when the current block (2610) touches the upper boundary of the maximum coding unit including the current block, the number of upper reference lines (2620) located above the current block (2610) is determined as N, and the number of left reference lines (2630) located to the left of the current block (2610) is determined as M, and M≥N. N may be determined as the value of the maximum line buffer set in the codec. For example, N=2, M=4, N=1, M=2, or N=1, M=4.

[0329] In one embodiment, when the current block touches the upper boundary of the maximum coding unit containing the current block, whether to use one reference line or a predetermined number of N reference lines may be determined through a flag. Whether to use one reference line or a predetermined number of N reference lines may be determined through the flag on a frame-by-frame, maximum coding unit, or block-by-block basis.

[0330] According to another embodiment, when the current block touches the upper boundary of the largest coding unit containing the current block, whether the decoding device uses one reference line or a predetermined number of N reference lines can be determined without a separate flag based on the availability of reference blocks of the current block.

[0331] When a flag is used for determining whether to use one reference line or a predetermined number of N reference lines when the current block touches the upper boundary of the largest coding unit containing the current block, the flag may be applied simultaneously to the luma and chroma blocks, or may be applied solely to the luma block or the chroma block. Furthermore, when the current block touches the upper boundary of the largest coding unit containing the current block, whether to use one reference line or a predetermined number of N reference lines may be determined based on different criteria (e.g., block size, intra mode, reference availability) for the luma block and the chroma block, respectively.

[0332] In another embodiment, when the current block touches the upper boundary of the largest coding unit containing the current block, whether to use one reference line or a predetermined number of N reference lines may be determined based on the size of the current block without signaling a flag.

[0333] In one embodiment, a flag of a tool (e.g., LM chroma, ALF (Adaptive Loop Filter)) that utilizes multiple reference lines may determine whether to use multiple reference lines when the current block touches the upper boundary of the largest coding unit that contains the current block.

[0334] In one embodiment, it may be permissible to use multiple reference lines only when the flag information of the tool is obtained in advance for each maximum coding unit and the flag is on more than N% of the time, and when the current block touches the upper boundary of the maximum coding unit containing the current block.

[0335] According to one embodiment, when it is determined whether tools of neighboring maximum coding units of a neighboring maximum coding unit including a current block are on, and when the flags of neighboring maximum coding units are on more than M% (for example, M is 50), it may be allowed to use multiple reference lines when the current block touches an upper boundary of the neighboring maximum coding unit including the current block. Specifically, all maximum coding units available as neighboring maximum coding units may be used, or selectively, information on whether tools of only some maximum coding units are on / off may be used. In addition, not all neighboring maximum coding units may be used, and only information on whether tools of coding units adjacent to a maximum coding unit including the current block are on / off may be used.

[0336] In one embodiment, the application may be determined without separate signaling by utilizing surrounding information.

[0337] In addition, referring to FIG. 26b, in the case where the current block (2611) does not touch the upper boundary line of the maximum encoding unit, the number of upper reference lines (2621) and left reference lines (2631) of the current block (2611) can both be determined as M.

[0338] Referring to Fig. 26c, when the number of upper reference lines (2622) of the current block (2612) is N and the number of left reference lines (2632) of the current block (2612) is M, if the number of upper reference lines and left reference lines must be the same, an area as large as MN above the N upper reference lines can be filled by padding using the upper pixels of the N upper reference lines.

[0339] In this case, pixels in an area as large as MN can be generated using pixels from one or more reference lines within the N upper reference lines. At this time, the generation method can utilize various methods such as padding, extrapolation, and filtering.

[0340] In one embodiment, when the number of upper reference lines is two or more, the gradient between two adjacent reference lines can be used for padding to fill an area as large as MN above the N upper reference lines.

[0341] In the case where the current block touches the upper boundary of the maximum coding unit containing the current block, if only one upper line is used, the way the tool is used will vary depending on the conditions. Therefore, as in the above embodiment, the number of reference lines originally required can be generated through methods such as padding, linear extrapolation, and non-linear filtering using one upper line. In this case, other information available in the surrounding area can also be utilized.

[0342] The present disclosure has been described with a focus on various embodiments. Those skilled in the art will appreciate that the present disclosure can be implemented in modified forms without departing from its essential characteristics. Therefore, the disclosed embodiments should be considered illustrative rather than restrictive. The scope of the present disclosure is set forth in the claims, not the foregoing description, and all differences within the scope equivalent thereto should be construed as being encompassed by the present disclosure.

[0343] Meanwhile, the embodiments of the present disclosure described above can be written as computer-executable programs and implemented in a general-purpose digital computer that executes the programs using a computer-readable recording medium. The computer-readable recording medium includes storage media such as magnetic storage media (e.g., ROM, floppy disks, hard disks, etc.) and optical readable media (e.g., CD-ROMs, DVDs, etc.).

Claims

1. A step of determining whether the current block touches the upper boundary of the largest encoding unit containing the current block; A step of determining an upper reference line of the current block as one reference line when it is determined that the current block touches the upper boundary line of the maximum encoding unit; A step of determining an upper reference line of the current block based on N reference lines, if it is determined that the current block does not touch the upper boundary line of the maximum encoding unit; Comprising a step of performing a prediction for the current block based on the determined upper reference line, A video decoding method, wherein N is a natural number.

2. In paragraph 1, A video decoding method, wherein the above N is determined by reference line information obtained from a bitstream.

3. In paragraph 2, A video decoding method, wherein if the current block is determined to be adjacent to the upper boundary line of the maximum encoding unit, the reference line information is not obtained.

4. In paragraph 1, If the above N is 2, A video decoding method, wherein the upper reference line is determined as a second reference line that contacts the upper side of a first reference line that contacts the upper side of the current block.

5. In paragraph 1, If the above N is 3, A video decoding method, wherein the upper reference line is determined as a fourth reference line touching the upper side of a third reference line touching the upper side of a second reference line touching the upper side of a first reference line touching the upper side of the current block.

6. In paragraph 1, A video decoding method, wherein the left reference line located on the left side of the current block is determined based on N reference lines.

7. In paragraph 1, A video decoding method, wherein if there is a reference line without sample values ​​in the upper reference line, a predetermined default value is padded with the sample values ​​of the reference line without sample values.

8. In paragraph 1, A video decoding method, wherein if a reference line without a sample value exists in the upper reference line, a reference sample value having a sample value is padded with the reference sample without a sample value, or a sample of the reference line without a sample value is regenerated using the sample value of the reference line having a sample value.

9. A step of determining whether the current luma block touches the upper boundary of the largest encoding unit containing the current luma block; A step of determining an upper reference line of the current luma block as one reference line when it is determined that the current luma block touches the upper boundary line of the maximum encoding unit; A step of determining an upper reference line of the current luma block as two reference lines if it is determined that the current luma block does not touch the upper boundary line of the maximum encoding unit; A video decoding method, comprising the step of performing a prediction for a current chroma block corresponding to the current luma block based on the determined upper reference line.

10. In paragraph 9, A video decoding method, wherein the two reference lines include a first reference line touching an upper side of the current luma block and a second reference line touching an upper side of the first reference line.

11. In paragraph 9, Weight information and deviation information are determined by using the relationship between the luma reference samples of the current luma block included in the upper reference line and the chroma reference samples contacting the upper side of the current chroma block, A video decoding method, wherein prediction for the current chroma block is performed by determining the current chroma block based on the weight information, the deviation information, and luma samples of the current luma block.

12. A step of determining whether the current block touches the upper boundary of the largest encoding unit containing the current block; A step of determining an upper reference line of the current block as one reference line when it is determined that the current block touches the upper boundary line of the maximum encoding unit; A step of determining an upper reference line of the current block based on N reference lines, if it is determined that the current block does not touch the upper boundary line of the maximum encoding unit; Comprising a step of performing a prediction for the current block based on the determined upper reference line, A video encoding method, wherein N is a natural number.

13. In paragraph 12, A video encoding method, comprising the step of generating reference line information representing the value of the above N.

14. In paragraph 13, A video encoding method, wherein if it is determined that the current block touches the upper boundary line of the maximum encoding unit, the reference line information is not generated.

15. In paragraph 11, If the above N is 3, A video encoding method, wherein the upper reference line is determined as a fourth reference line touching the upper side of a third reference line touching the upper side of a second reference line touching the upper side of a first reference line touching the upper side of the current block.

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