KR102504643B1 - Method and apparatus for prediction based on block shape - Google Patents

Abstract

A video decoding method, a decoding apparatus, an encoding method, and an encoding apparatus. In video encoding and decoding, a plurality of divided blocks are generated by dividing a target block. A prediction mode is derived for at least some of the plurality of divided blocks, and predictions for the plurality of divided blocks may be performed based on the derived prediction mode. In performing prediction on a divided block, information related to the target block may be used, and information related to other previously predicted divided blocks of the divided block may be used.

Description

Prediction method and apparatus based on block shape {METHOD AND APPARATUS FOR PREDICTION BASED ON BLOCK SHAPE}

The following embodiments relate to a video decoding method, a decoding apparatus, an encoding method, and an encoding apparatus, and relates to a method and apparatus for performing prediction based on a shape of a block in video encoding and decoding.

Through the continuous development of the information communication industry, broadcasting services having high definition (HD) resolution have been spread worldwide. Through this proliferation, many users have become accustomed to high-resolution and high-definition images and/or videos.

In order to satisfy users' demand for high image quality, many organizations are accelerating the development of next-generation video devices. Users' interest in Ultra High Definition (UHD) TV, which has four times higher resolution than FHD TV, as well as High Definition TV (HDTV) and Full HD (FHD) TV. has increased, and according to this increase in interest, an image encoding/decoding technology for an image having a higher resolution and quality is required.

An image encoding/decoding device and method for encoding/decoding high-resolution and high-quality images, such as inter prediction technology, intra prediction technology, entropy encoding technology, etc. can be used. The inter-prediction technique may be a technique of predicting a value of a pixel included in a current picture using a temporally previous picture and/or a temporally subsequent picture. Intra-prediction technology may be a technology of predicting a value of a pixel included in a current picture using pixel information in the current picture. The entropy coding technique may be a technique of allocating a short code to a symbol with a high frequency of occurrence and a long code to a symbol with a low frequency of occurrence.

Various prediction methods have been developed to improve the efficiency and accuracy of intra prediction and/or inter prediction. For example, a block may be partitioned for efficient prediction, and prediction may be performed on each of the blocks generated by the partitioning. Depending on whether or not a block is divided, prediction efficiency may vary greatly.

An embodiment may provide an encoding apparatus, an encoding method, a decoding apparatus, and a decoding method for dividing a block based on the size and/or shape of the block and inducing a prediction mode for the divided block.

An embodiment may provide an encoding apparatus, an encoding method, a decoding apparatus, and a decoding method for performing prediction on a divided block according to an induced prediction mode.

In one aspect, generating a plurality of divided blocks by dividing the target block; inducing a prediction mode for at least some of the plurality of divided blocks; and performing predictions on the plurality of divided blocks based on the derived prediction mode.

In another aspect, generating a plurality of divided blocks by dividing the target block; inducing a prediction mode for at least some of the plurality of divided blocks; and performing predictions on the plurality of divided blocks based on the derived prediction mode.

Whether to split the target block may be determined based on information related to the target block.

Whether to split the target block and the type of split may be determined based on a block split indicator.

The target block may be divided based on the size of the target block.

The target block may be divided based on the shape of the target block.

A prediction mode may be derived for a specified partitioned block among the plurality of partitioned blocks.

The specified divided block may be a block at a specified position among the plurality of divided blocks.

A prediction mode derived for the specified split block may be used for remaining blocks other than the specified split block among the plurality of split blocks.

A prediction mode determined by a combination of a prediction mode derived for the specified divided block and other prediction modes may be used for remaining blocks other than the specific divided block among the plurality of divided blocks.

In deriving the prediction mode, a Most Probable Mode (MPM) list may be used.

The MPM list may be plural.

MPM candidate modes of the plurality of MPM lists may not overlap each other.

The MPM list may be configured for a specific unit.

The specified unit may be the target block.

MPM lists for the plurality of divided blocks may be constructed based on one or more reference blocks of the target block.

In prediction of a second block among the plurality of divided blocks, a prediction mode derived for a first block among the plurality of divided blocks may be used.

Reconstructed pixels of the first block may be used as reference samples for prediction of the second block.

Reference samples used for prediction of the plurality of divided blocks may be reconstructed pixels adjacent to the target block.

The prediction mode may be derived for a lowermost block or a rightmost block among the plurality of divided blocks.

In prediction of the lowermost block, reconstructed pixels adjacent to an upper end of the target block may be used as reference pixels.

Prediction of the plurality of divided blocks may be performed according to a predefined order.

The predefined order is the order from the lowest block to the highest block, the order from the rightmost block to the leftmost block, the lowest block is selected first, and then the second from the lowest to the highest block It may be an order in which up to a block of is sequentially selected, or an order in which the rightmost block is selected first, and then the leftmost block to the second block from the rightmost block are sequentially selected.

In another aspect, deriving a prediction mode; generating a plurality of divided blocks by dividing the target block; and performing predictions on the plurality of divided blocks based on the derived prediction mode.

An encoding apparatus, an encoding method, a decoding apparatus, and a decoding method for dividing a block based on the size and/or shape of the block and inducing a prediction mode for the divided block are provided.

An encoding apparatus, an encoding method, a decoding apparatus, and a decoding method for performing prediction on divided blocks according to the derived prediction mode are provided.

1 is a block diagram showing a configuration according to an embodiment of an encoding device to which the present invention is applied.
2 is a block diagram showing a configuration according to an embodiment of a decoding device to which the present invention is applied.
3 is a diagram schematically illustrating a division structure of an image when encoding and decoding an image.
4 is a diagram illustrating a form of a prediction unit (PU) that may be included in a coding unit (CU).
5 is a diagram illustrating a form of a transform unit (TU) that may be included in a coding unit (CU).
6 is a diagram for explaining an embodiment of an intra prediction process.
7 is a diagram for explaining positions of reference samples used in an intra prediction process.
8 is a diagram for explaining an embodiment of an inter prediction process.
9 shows spatial candidates according to an example.
10 illustrates an order of adding motion information of spatial candidates to a merge list according to an example.
11 illustrates a process of transformation and quantization according to an example.
12 is a structural diagram of an encoding device according to an embodiment.
13 is a structural diagram of a decryption device according to an embodiment.
14 is a flowchart of a prediction method according to an embodiment.
15 is a flowchart of a block division method according to an embodiment.
16 illustrates a target block having a size of 8x4 according to an example.
17 illustrates divided blocks having a size of 4x4 according to an example.
18 illustrates a target block having a size of 4x16 according to an example.
19 shows divided blocks having a size of 8x4 according to an example.
20 shows divided blocks having a size of 4x4 according to an example.
21 is a flowchart of a method of deriving a prediction mode for a divided block according to an example.
22 illustrates prediction of a divided block according to an example.
23 illustrates prediction of a divided block using a reconstructed block of the divided block according to an example.
24 illustrates prediction of a divided block using a reference pixel outside the divided block according to an example.
25 illustrates prediction of four divided blocks according to an example.
26 illustrates prediction of a first block after prediction of a fourth block is performed according to an example.
27 illustrates prediction of a second block according to an example.
28 shows prediction of a third block according to an example.
29 is a flowchart of a prediction method according to an embodiment.
30 illustrates derivation of a prediction mode for a target block according to an example.
31 is a flowchart of a method of predicting a target block and generating a bitstream according to an embodiment.
32 is a flowchart of a method of predicting a target block using a bitstream according to an embodiment.
33 illustrates division of an upper block according to an example.
34 illustrates division of a target block according to an example.
35 is a signal flowchart illustrating a method of encoding and decoding an image according to an exemplary embodiment.

Since the present invention can make various changes and have various embodiments, specific embodiments will be illustrated in the drawings and described in detail in the detailed description. However, this is not intended to limit the present invention to specific embodiments, and should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS For detailed descriptions of exemplary embodiments described below, reference is made to the accompanying drawings, which illustrate specific embodiments by way of example. These embodiments are described in sufficient detail to enable those skilled in the art to practice the embodiments. It should be understood that the various embodiments are different, but need not be mutually exclusive. For example, specific shapes, structures, and characteristics described herein may be implemented in one embodiment in another embodiment without departing from the spirit and scope of the invention. Additionally, it should be understood that the location or arrangement of individual components within each disclosed embodiment may be changed without departing from the spirit and scope of the embodiment. Accordingly, the detailed description set forth below is not to be taken in a limiting sense, and the scope of the exemplary embodiments, if properly described, is limited only by the appended claims, along with all equivalents as claimed by those claims.

Like reference numbers in the drawings indicate the same or similar function throughout the various aspects. The shapes and sizes of elements in the drawings may be exaggerated for clarity.

In the present invention, terms such as first and second may be used to describe various components, but the components should not be limited by the terms. These terms are only used for the purpose of distinguishing one component from another. For example, a first element may be termed a second element, and similarly, a second element may be termed a first element, without departing from the scope of the present invention. The terms and/or include any combination of a plurality of related recited items or any of a plurality of related recited items.

When a component is referred to as being “connected” or “connected” to another component, the two components may be directly connected or connected to each other, but It will be understood that other components may exist in the middle of the two components. When a component is referred to as “directly connected” or “directly connected” to another component, it should be understood that no other component exists between the two components.

The components appearing in the embodiments of the present invention are shown independently to represent different characteristic functions, and it does not mean that each component is composed of separate hardware or a single software unit. That is, each component is listed and included as each component for convenience of description, and at least two of each component are combined to form one component, or one component is divided into a plurality of components to perform functions. It can be performed, and integrated embodiments and separate embodiments of each of these components are also included in the scope of the present invention as long as they do not depart from the essence of the present invention.

In addition, the description of "including" a specific configuration in the exemplary embodiments does not exclude configurations other than the specific configuration above, and additional configurations are the implementation of the exemplary embodiments or the technical idea of the exemplary embodiments. This means that it can be included in the scope.

Terms used in the present invention are only used to describe specific embodiments, and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly dictates otherwise. In the present invention, terms such as "comprise" or "having" are intended to designate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, but one or more other features It should be understood that the presence or addition of numbers, steps, operations, components, parts, or combinations thereof is not precluded. That is, the description of "including" a specific configuration in the present invention does not exclude configurations other than the corresponding configuration, and additional configurations may also be included in the practice of the present invention or the scope of the technical spirit of the present invention.

Hereinafter, embodiments will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily practice the embodiments. In describing the embodiments, if it is determined that a detailed description of a related known configuration or function may obscure the gist of the present specification, the detailed description will be omitted. In addition, the same reference numerals are used for the same components in the drawings, and duplicate descriptions of the same components are omitted.

Hereinafter, an image may mean one picture constituting a video, and may also indicate the video itself. For example, "encoding and/or decoding an image" may mean "encoding and/or decoding a video", and may mean "encoding and/or decoding one of images constituting a video". may be

Hereinafter, the terms “video” and “motion picture” may be used interchangeably and may be used interchangeably.

Hereinafter, the target image may be an encoding target image that is an encoding target and/or a decoding target image that is a decoding target. Also, the target image may be an input image input to an encoding device or an input image input to a decoding device.

Hereinafter, the terms "video", "picture", "frame" and "screen" may be used in the same meaning and may be used interchangeably.

Hereinafter, the target block may be an encoding target block that is an encoding target and/or a decoding target block that is a decoding target. Also, the target block may be a current block that is a target of current encoding and/or decoding. For example, the terms “target block” and “current block” may be used interchangeably and may be used interchangeably.

Hereinafter, the terms “block” and “unit” may be used interchangeably and may be used interchangeably. Or "block" may represent a specific unit.

In the following, the terms "region" and "segment" may be used interchangeably.

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

In embodiments, each of the specified information, data, flags and elements, attributes, etc. may have a value. A value "0" of information, data, flags and elements, attributes, etc. may represent a logical false or a first predefined value. That is to say, the value "0", false, logic false and the first predefined value may be used interchangeably. A value "1" of information, data, flags and elements, attributes, etc. may represent logical true or a second predefined value. In other words, the value "1", true, logically true, and the second predefined value may be used interchangeably.

When a variable such as i or j is used to indicate a row, column, or index, the value of i may be an integer greater than or equal to 0, or may be an integer greater than or equal to 1. That is to say, row, column, index, etc. may be counted from 0, in embodiments, may be counted from 1.

Below, terms used in the embodiments are explained.

Encoder: Means a device that performs encoding.

Decoder: Means a device that performs decoding.

Unit: A unit may represent a unit of encoding and decoding of an image. The terms "unit" and "block" may be used interchangeably and may be used interchangeably.

- A unit can be an MxN array of samples. M and N may each be a positive integer. A unit may commonly refer to a two-dimensional array of samples.

- In encoding and decoding of an image, a unit may be a region created by dividing one image. One image may be divided into a plurality of units. Alternatively, the unit may refer to the divided parts when one image is divided into subdivided parts and encoding or decoding of the divided parts is performed.

- In encoding and decoding of an image, a predefined process for a unit may be performed according to the type of unit.

- Depending on the function, the type of unit is a macro unit, a coding unit (CU), a prediction unit (PU), a residual unit, and a transform unit (TU), etc. can be classified as Or, depending on the function, the unit may be a block, a macroblock, a coding tree unit (CTU), a coding tree block, a coding unit, a coding block, It may mean a prediction unit, a prediction block, a residual unit, a residual block, a transform unit, a transform block, and the like.

- A unit may refer to information including a luma component block, a chroma component block corresponding to the luma component block, and a syntax element for each block, in order to be distinguished from the block.

- Units may vary in size and shape. Also, units can have various sizes and shapes. In particular, the shape of the unit may include not only a square but also a two-dimensional geometric figure such as a rectangle, a trapezoid, a triangle, and a pentagon.

- In addition, the unit information may include at least one of a unit type indicating a coding unit, a prediction unit, a residual unit, a transform unit, and the like, a size of the unit, a depth of the unit, and an encoding and decoding order of the unit.

- One unit can be further divided into sub-units having a smaller size than the unit.

Unit depth: Unit depth may mean the degree of division of a unit. Also, the unit depth may indicate a level at which a unit exists when the unit is expressed in a tree structure.

- Unit division information may include a unit depth related to the depth of a unit. Unit depth may indicate the number and/or extent to which a unit is divided.

- In the tree structure, the root node has the shallowest depth and the leaf node has the deepest depth.

- One unit may be hierarchically divided into a plurality of sub-units while having depth information based on a tree structure. In other words, a unit and a sub-unit generated by division of the unit may correspond to a node and a child node of the node, respectively. Each divided sub-unit may have a unit depth. Since unit depth represents the number and/or degree of division of a unit, division information of a sub-unit may include information about the size of the sub-unit.

- In the tree structure, the highest node may correspond to the first non-split unit. The highest node may be referred to as a root node. Also, the highest node may have the smallest depth value. In this case, the highest node may have a depth of level 0.

- A node with a depth of level 1 may represent a unit created as the original unit is split once. A node with a depth of level 2 may represent a unit created as the original unit is split twice.

- A node with a depth of level n may represent a unit created as the initial unit is split n times.

- A leaf node may be the lowest node and may be a node that cannot be further divided. The depth of a leaf node may be the maximum level. For example, the predefined value of the maximum level may be 3.

Sample: A sample may be a base unit constituting a block. A sample may be represented as values from 0 to 2 ^Bd -1 according to a bit depth (Bd).

- A sample can be a pixel or a pixel value.

- In the following, the terms "pixel", "pixel" and "sample" may be used in the same meaning and may be used interchangeably.

Coding Tree Unit (CTU): A CTU may consist of one luminance component (Y) coding tree block and two chrominance component (Cb, Cr) coding tree blocks related to the luminance component coding tree block. there is. Also, the CTU may mean including the above blocks and syntax elements for each block of the above blocks.

- Each coding tree unit may be split using one or more partitioning schemes such as a quad tree and a binary tree to form subunits such as a coding unit, a prediction unit, and a transform unit. .

- CTU may be used as a term to refer to a pixel block, which is a processing unit in the process of decoding and encoding an image, as in segmentation of an input image.

Coding Tree Block (CTB): A coding tree block may be used as a term to refer to any one of a Y coding tree block, a Cb coding tree block, and a Cr coding tree block.

Neighbor block: A block adjacent to a target block. A block adjacent to the target block may mean a block whose boundary meets the target block or a block located within a predetermined distance from the target block. A neighboring block may refer to a block adjacent to a vertex of a target block. Here, the block adjacent to the vertex of the target block may be a block vertically adjacent to a neighboring block horizontally adjacent to the target block or a block horizontally adjacent to a neighboring block vertically adjacent to the target block. A neighboring block may mean a restored neighboring block.

Prediction unit: It may mean a base unit for prediction such as inter prediction, intra prediction, inter compensation, intra compensation, and motion compensation.

- One prediction unit may be divided into a plurality of smaller-sized partitions or sub-prediction units. A plurality of partitions may also be a basis unit in performing prediction or compensation. A partition generated by division of a prediction unit may also be a prediction unit.

Prediction unit partition: This may mean a form in which a prediction unit is divided.

Reconstructed neighboring unit: A reconstructed neighboring unit may be a unit that has already been decoded and reconstructed in the vicinity of a target unit.

- The reconstructed neighbor unit may be a spatial neighbor unit or a temporal neighbor unit to the target unit.

- The reconstructed spatial neighboring unit may be a unit in the current picture and already reconstructed through encoding and/or decoding.

- The reconstructed temporal neighboring unit may be a unit in the reference picture and already reconstructed through encoding and/or decoding. A position of the reconstructed temporal neighboring unit within the reference image may be the same as a position within the current picture of the target unit or may correspond to a position within the current picture of the target unit.

Parameter set: A parameter set may correspond to header information among structures in a bitstream. For example, the parameter set may include a sequence parameter set, a picture parameter set, an adaptation parameter set, and the like.

Rate-distortion optimization: The encoding device uses a combination of the size of the coding unit, the prediction mode, the size of the prediction unit, motion information, and the size of the conversion unit to provide high encoding efficiency. Distortion optimization can be used.

- The rate-distortion optimization method may calculate a rate-distortion cost of each combination in order to select an optimal combination among the above combinations. The rate-distortion cost can be calculated using Equation 1 below. In general, a combination that minimizes the rate-distortion cost can be selected as an optimal combination in the rate-distortion optimization method.

[Formula 1]

- D can represent distortion. D may be the mean square error of difference values between the original transform coefficients and the reconstructed transform coefficients within the transform unit.

- R can represent rate. R may represent a bit rate using related context information.

- λ may represent a Lagrangian multiplier. R may include not only coding parameter information such as a prediction mode, motion information, and a coded block flag, but also bits generated by encoding transform coefficients.

- The encoding device may perform processes such as inter prediction and/or intra prediction, transformation, quantization, entropy encoding, inverse quantization, and inverse transformation to calculate accurate D and R. These processes can greatly increase complexity in an encoding device.

Bitstream: A bitstream may mean a string of bits including coded image information.

Parameter set: A parameter set may correspond to header information among structures in a bitstream.

-The parameter set is at least one of a video parameter set (VPS), a sequence parameter set (SPS), a picture parameter set (PPS), and an adaptation parameter set (APS) can include Also, the parameter set may include slice header information and tile header information.

Parsing: Parsing may mean determining a value of a syntax element by entropy-decoding a bitstream. Alternatively, parsing may mean entropy decoding itself.

Symbol: This may mean at least one of a syntax element, a coding parameter, and a transform coefficient of a coding target unit and/or a decoding target unit. Also, a symbol may mean an object of entropy encoding or a result of entropy decoding.

Reference picture: A reference picture may refer to an image that a unit refers to for inter prediction or motion compensation. Alternatively, the reference picture may be an image including a reference unit referred to by a target unit for inter prediction or motion compensation.

Hereinafter, the terms “reference picture” and “reference image” may be used interchangeably and may be used interchangeably.

Reference picture list: The reference picture list may be a list including one or more reference pictures used for inter prediction or motion compensation.

- The types of reference picture lists are List Combined (LC), List 0 (L0), List 1 (L1), List 2 (List 2; L2), and List 3 (List 3; L3). ), etc. may be present.

- One or more reference picture lists may be used for inter prediction.

Inter prediction indicator: The inter prediction indicator may indicate the direction of inter prediction of the target unit. Inter prediction can be one of uni-prediction and bi-prediction, etc. Alternatively, the inter prediction indicator may indicate the number of reference images used when generating a prediction unit of a target unit. Alternatively, the inter prediction indicator may indicate the number of prediction blocks used for inter prediction or motion compensation of the target unit.

Reference picture index: The reference picture index may be an index indicating a specific reference picture in a reference picture list.

Motion Vector (MV): A motion vector may be a two-dimensional vector used in inter prediction or motion compensation. A motion vector may mean an offset between an encoding target image/decoding target image and a reference image.

- For example, MV can be expressed as (mv _x , mv _y ). mv _x may represent a horizontal component, and mv _y may represent a vertical component.

Search range: The search range may be a two-dimensional area where MVs are searched during inter prediction. For example, the size of the search area may be MxN. M and N may each be a positive integer.

Motion vector candidate: A motion vector candidate may mean a block as a prediction candidate or a motion vector of a block as a prediction candidate when predicting a motion vector.

- A motion vector candidate may be included in a motion vector candidate list.

Motion vector candidate list: The motion vector candidate list may refer to a list constructed using one or more motion vector candidates.

Motion vector candidate index: The motion vector candidate index may mean an indicator indicating a motion vector candidate in the motion vector candidate list. Alternatively, the motion vector candidate index may be an index of a motion vector predictor.

Motion information: Motion information includes not only motion vectors, reference picture indices and inter prediction indicators, but also reference picture list information, reference pictures, motion vector candidates, motion vector candidate indices, merge candidates and merge indices, etc. It may mean information including at least one of

Merge candidate list: A merge candidate list may refer to a list constructed using merge candidates.

Merge candidate: Spatial merge candidate, temporal merge candidate, combined merge candidate, combined bi-prediction merge candidate, zero merge candidate, etc. A merge candidate may include motion information such as an inter prediction indicator, a reference picture index for each list, and a motion vector.

Merge index: A merge index may be an indicator pointing to a merge candidate in a merge candidate list.

- The merge index may indicate a reconstructed unit that derives a merge candidate from among reconstructed units spatially adjacent to the target unit and reconstructed units temporally adjacent to the target unit.

- The merge index may indicate at least one of the motion information of the merge candidate.

Transform unit: A transform unit may be a basic unit in residual signal encoding and/or residual signal decoding, such as transform, inverse transform, quantization, inverse quantization, transform coefficient encoding, and transform coefficient decoding. One transform unit may be divided into a plurality of smaller transform units.

Scaling: Scaling may refer to a process of multiplying a transform coefficient level by a factor.

- As a result of the scaling to the transform coefficient level, a transform coefficient can be generated. Scaling may be referred to as dequantization.

Quantization Parameter (QP): A quantization parameter may mean a value used when generating a transform coefficient level for a transform coefficient in quantization. Alternatively, it may mean a value used when generating a transform coefficient by scaling the transform coefficient level in inverse quantization. Alternatively, the quantization parameter may be a value mapped to a quantization step size.

Delta quantization parameter: The delta quantization parameter means a differential value between a predicted quantization parameter and a quantization parameter of a unit to be encoded/decoded.

Scan: A scan may refer to a method of arranging the order of coefficients within a unit, block or matrix. For example, arranging a 2D array into a 1D array may be referred to as a scan. Alternatively, arranging a one-dimensional array into a two-dimensional array may also be referred to as scan or inverse scan.

Transform coefficient: A transform coefficient may be a coefficient value generated by performing transformation in an encoding device. Alternatively, the transform coefficient may be a coefficient value generated by performing at least one of entropy decoding and inverse quantization in the decoding apparatus.

- A quantized level obtained by applying quantization to a transform coefficient or a residual signal or a quantized transform coefficient level may also be included in the meaning of a transform coefficient.

Quantized level: The quantized level may refer to a value generated by performing quantization on a transform coefficient or a residual signal in an encoding device. Alternatively, the quantized level may mean a value to be subjected to inverse quantization when the decoding apparatus performs inverse quantization.

- A quantized transform coefficient level, which is a result of transform and quantization, may also be included in the meaning of the quantized level.

Non-zero transform coefficient: A non-zero transform coefficient may mean a transform coefficient having a non-zero value or a transform coefficient level having a non-zero value. Alternatively, the non-zero transform coefficient may refer to a transform coefficient whose magnitude is not 0 or a transform coefficient level whose magnitude is not 0.

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

Quantization matrix coefficient: A quantization matrix coefficient may mean each element in a quantization matrix. Quantization matrix coefficients may also be referred to as matrix coefficients.

Default matrix: The default matrix may be a quantization matrix predefined in an encoding device and a decoding device.

Non-default matrix: The non-default matrix may be a quantization matrix that is not predefined in the encoding device and the decoding device. The non-default matrix may be signaled from the encoding device to the decoding device.

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

The encoding device 100 may be an encoder, a video encoding device, or an image encoding device. A video may include one or more images. The encoding apparatus 100 may sequentially encode one or more images of a video.

Referring to FIG. 1, an encoding apparatus 100 includes an inter prediction unit 110, an intra prediction unit 120, a switch 115, a subtractor 125, a transform unit 130, a quantization unit 140, and entropy encoding. It may include a unit 150, an inverse quantization unit 160, an inverse transform unit 170, an adder 175, a filter unit 180, and a reference picture buffer 190.

The encoding apparatus 100 may perform encoding on a target image using an intra mode and/or an inter mode.

Also, the encoding device 100 may generate a bitstream including encoding information through encoding of a target image, and output the generated bitstream. The generated bitstream may be stored in a computer readable recording medium and may be streamed through a wired/wireless transmission medium.

As the prediction mode, if the intra mode is used, the switch 115 can be switched to intra. As the prediction mode, when the inter mode is used, the switch 115 can be switched to inter.

The encoding apparatus 100 may generate a prediction block for the target block. Also, after the prediction block is generated, the encoding apparatus 100 may encode a residual between the target block and the prediction block.

When the prediction mode is the intra mode, the intra predictor 120 may use pixels of already encoded/decoded blocks adjacent to the target block as reference samples. The intra predictor 120 may perform spatial prediction on the target block using the reference sample, and generate prediction samples for the target block through the spatial prediction.

The inter prediction unit 110 may include a motion estimation unit and a motion compensation unit.

When the prediction mode is the inter mode, the motion prediction unit may search for a region that best matches the target block from the reference image in the motion prediction process, and derive motion vectors for the target block and the searched region using the searched region. can do.

The reference picture may be stored in the reference picture buffer 190, and may be stored in the reference picture buffer 190 when coding and/or decoding of the reference picture is processed.

The motion compensator may generate a prediction block for the target block by performing motion compensation using a motion vector. Here, the motion vector may be a 2D vector used for inter prediction. Also, the motion vector may indicate an offset between the target image and the reference image.

The motion estimation unit and the motion compensation unit may generate a prediction block by applying an interpolation filter to a partial region in a reference image when a motion vector has a non-integer value. In order to perform inter prediction or motion compensation, methods of motion prediction and motion compensation of PUs included in the CU based on the CU include skip mode, merge mode, and advanced motion vector prediction. Prediction (AMVP) mode and current picture reference mode may be determined, and inter prediction or motion compensation may be performed according to each mode.

The subtractor 125 may generate a residual block that is a difference between the target block and the prediction block. A residual block may be referred to as a residual signal.

The residual signal may mean a difference between the original signal and the prediction signal. Alternatively, the residual signal may be a signal generated by transforming, quantizing, or transforming and quantizing the difference between the original signal and the prediction signal. A residual block may be a residual signal for a block unit.

The transform unit 130 may generate transform coefficients by performing transform on the residual block, and may output the generated transform coefficients. Here, the transform coefficient may be a coefficient value generated by performing transform on the residual block.

When a transform skip mode is applied, the transform unit 130 may skip transforming the residual block.

A quantized transform coefficient level or a quantized level may be generated by applying quantization to the transform coefficients. Hereinafter, in the embodiments, a quantized transform coefficient level and a quantized level may also be referred to as a transform coefficient.

The quantization unit 140 may generate a quantized transform coefficient level or a quantized level by quantizing a transform coefficient according to a quantization parameter. The quantization unit 140 may output the generated quantized transform coefficient level or the generated quantized level. At this time, the quantization unit 140 may quantize the transform coefficient using a quantization matrix.

The entropy encoding unit 150 may generate a bitstream by performing entropy encoding according to a probability distribution based on values calculated by the quantization unit 140 and/or coding parameter values calculated in the encoding process. . The entropy encoding unit 150 may output the generated bitstream.

The entropy encoding unit 150 may perform entropy encoding on information about pixels of an image and information for decoding an image. For example, information for decoding an image may include a syntax element and the like.

A coding parameter may be information required for encoding and/or decoding. The coding parameter may include information that is encoded in the encoding device 100 and transmitted from the encoding device 100 to the decoding device, and may include information that can be inferred during an encoding or decoding process. For example, as information transmitted to the decoding device, there is a syntax element.

For example, coding parameters include prediction mode, motion vector, reference picture index, coded block pattern, presence/absence of a residual signal, transform coefficient, quantized transform coefficient, quantization parameter, block size, block partition ) may include values or statistics such as information. The prediction mode may indicate an intra prediction mode or an inter prediction mode.

The residual signal may represent a difference between the original signal and the predicted signal. Alternatively, the residual signal may be a signal generated by transforming a difference between the original signal and the predicted signal. Alternatively, the residual signal may be a signal generated by transforming and quantizing the difference between the original signal and the predicted signal.

When entropy encoding is applied, a small number of bits may be allocated to a symbol having a high probability of occurrence, and a large number of bits may be allocated to a symbol having a low probability of occurrence. As symbols are represented through such allocation, the size of bitstrings for symbols that are encoding targets can be reduced. Therefore, compression performance of image encoding can be improved through entropy encoding.

In addition, the entropy encoding unit 150 uses exponential golomb, context-adaptive variable length coding (CAVLC), and context-adaptive binary arithmetic coding (Context-Adaptive Binary Coding) for entropy encoding. A coding method such as Arithmetic Coding (CABAC) may be used. For example, the entropy encoding unit 150 may perform entropy encoding using a variable length coding/code (VLC) table. For example, the entropy encoding unit 150 may derive a binarization method for a target symbol. Also, the entropy encoding unit 150 may derive a probability model of the target symbol/bin. The entropy encoding unit 150 may perform arithmetic encoding using the derived binarization method, probability model, and context model.

The entropy encoding unit 150 may change a coefficient of a 2D block form into a 1D vector form through a transform coefficient scanning method in order to encode a transform coefficient level.

A coding parameter may include information derived from an encoding process or a decoding process as well as information (or flags, indexes, etc.) encoded in an encoding device and signaled from an encoding device to a decoding device, such as a syntax element. there is. Also, the coding parameter may include information required for encoding or decoding an image. For example, the size of the unit/block, the depth of the unit/block, the division information of the unit/block, the division structure of the unit/block, the information indicating whether the unit/block is divided in a quad-tree form, the unit/block Information indicating whether the binary-tree is partitioned, the binary-tree partitioning direction (horizontal direction or vertical direction), the binary-tree partitioning type (symmetric partitioning or asymmetric partitioning), prediction method (intra prediction or inter prediction) ), intra prediction mode/direction, reference sample filtering method, prediction block filtering method, prediction block boundary filtering method, filter tap of filtering, filter coefficient of filtering, inter prediction mode, motion information, motion vector, reference picture index, inter prediction Direction, inter prediction indicator, reference picture list, reference picture, motion vector predictor, motion vector prediction candidate, motion vector candidate list, information indicating whether merge mode is used, merge candidate, merge candidate list, skip mode information indicating whether to use, type of interpolation filter, filter tab of interpolation filter, filter coefficient of interpolation filter, motion vector size, motion vector expression accuracy, transformation type, transformation size, information indicating whether to use a first-order transformation, Information indicating whether additional (secondary) transform is used, primary transform index, secondary transform index, information indicating presence/absence of a residual signal, coded block pattern, coded block flag ), quantization parameter, quantization matrix, information on intra-loop filters, information on whether to apply intra-loop filters, coefficients of intra-loop filters, filter taps of intra-loops, shape of intra-loop filters /form, information indicating whether to apply deblocking filter, information indicating whether to apply deblocking filter coefficients, deblocking filter taps, deblocking filter strength, deblocking filter shape/shape, adaptive sample offset , adaptive sample offset value, adaptive sample offset category, adaptive Sample offset type, whether adaptive in-loop filter is applied, adaptive in-loop filter coefficients, adaptive in-loop filter tap, adaptive in-loop filter shape/shape, binarization/inverse binarization Method, context model, context model determination method, context model update method, whether to perform regular mode, whether to perform bypass mode, context bin, bypass bin, conversion coefficient, conversion coefficient level, conversion coefficient level scanning method, At least one of the display/output order of an image, slice identification information, slice type, slice division information, tile identification information, tile type, tile division information, picture type, bit depth, information about a luminance signal, and information about a chrominance signal Values or combined forms can be included in coding parameters.

Here, signaling the flag or index means that the encoding apparatus 100 entropy-encodes the flag or index to generate an entropy-encoded flag or an entropy-encoded index into a bitstream. It may mean including, and in the decoding apparatus 200, it may mean acquiring a flag or index by performing entropy decoding on an entropy-encoded flag or an entropy-encoded index extracted from a bitstream. .

Since encoding through inter prediction is performed by the encoding apparatus 100, the encoded target image may be used as a reference image for other image(s) to be processed later. Accordingly, the encoding apparatus 100 may reconstruct or decode the encoded target image and store the reconstructed or decoded image in the reference picture buffer 190 as a reference image. Inverse quantization and inverse transformation may be performed on the encoded target image for decoding.

The quantized level may be inversely quantized in the inverse quantization unit 160 and inversely transformed in the inverse transformation unit 170 . The inverse quantized and/or inverse transformed coefficients may be summed with the prediction block through the adder 175. A reconstructed block may be generated by adding the inverse quantized and/or inverse transformed coefficients and the prediction block. Here, the inverse quantized and/or inverse transformed coefficient may refer to a coefficient obtained by performing at least one of dequantization and inverse-transformation, and may refer to a reconstructed residual block.

The reconstructed block may pass through the filter unit 180 . The filter unit 180 converts at least one of a deblocking filter, a sample adaptive offset (SAO), and an adaptive loop filter (ALF) into a reconstructed block or a reconstructed block. It can be applied to pictures. The filter unit 180 may also be referred to as an in-loop filter.

The deblocking filter may remove block distortion generated at a boundary between blocks. In order to determine whether to apply the deblocking filter, it may be determined whether to apply the deblocking filter to the target block based on pixel(s) included in several columns or rows included in the block. When a deblocking filter is applied to a target block, the applied filter may vary according to the required strength of deblocking filtering. In other words, among different filters, a filter determined according to the strength of deblocking filtering may be applied to the target block.

SAO may add an appropriate offset to a pixel value of a pixel to compensate for a coding error. The SAO may perform correction using an offset on a difference between an original image and an image to which deblocking is applied in units of pixels for an image to which deblocking is applied. After dividing the pixels included in the image into a certain number of areas, a method of determining an area to be offset from among the divided areas and applying the offset to the determined area may be used, and edge information of each pixel of the image may be used. A method of applying an offset taking into account may be used.

ALF may perform filtering based on a value obtained by comparing the reconstructed image and the original image. After dividing the pixels included in the image into predetermined groups, a filter to be applied to the divided groups may be determined, and filtering may be performed differentially for each group. Information related to whether to apply the adaptive loop filter may be signaled for each CU. , the shape and filter coefficients of ALF to be applied to each block may be different for each block.

A reconstructed block or a reconstructed image that has passed through the filter unit 180 may be stored in the reference picture buffer 190 . A reconstructed block that has passed through the filter unit 180 may be part of a reference picture. In other words, the reference picture may be a reconstructed picture composed of reconstructed blocks that have passed through the filter unit 180. The stored reference picture can then be used for inter prediction.

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

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

Referring to FIG. 2 , the decoding apparatus 200 includes an entropy decoding unit 210, an inverse quantization unit 220, an inverse transform unit 230, an intra prediction unit 240, an inter prediction unit 250, and an adder 255. , a filter unit 260 and a reference picture buffer 270.

The decoding device 200 may receive the bitstream output from the encoding device 100. The decoding apparatus 200 may receive a bitstream stored in a computer-readable recording medium or may receive a bitstream streamed through a wired/wireless transmission medium.

The decoding apparatus 200 may perform intra mode and/or inter mode decoding on a bitstream. Also, the decoding apparatus 200 may generate a reconstructed image or a decoded image through decoding, and output the generated reconstructed image or decoded image.

For example, conversion to an intra mode or an inter mode according to a prediction mode used for decoding may be performed by a switch. When the prediction mode used for decoding is the intra mode, the switch may be switched to the intra mode. When the prediction mode used for decoding is the inter mode, the switch may be switched to inter mode.

The decoding apparatus 200 may obtain a reconstructed residual block by decoding the input bitstream and generate a prediction block. When the reconstructed residual block and the prediction block are obtained, the decoding apparatus 200 may generate a reconstructed block to be decoded by adding the reconstructed residual block and the prediction block.

The entropy decoding unit 210 may generate symbols by performing entropy decoding on the bitstream based on the probability distribution of the bitstream. The generated symbols may include symbols in the form of quantized levels. Here, the entropy decoding method may be similar to the above-described entropy encoding method. For example, the entropy decoding method may be a reverse process of the above-described entropy encoding method.

The quantized coefficient may be inversely quantized in the inverse quantization unit 220 . The inverse quantization unit 220 may generate inverse quantized coefficients by performing inverse quantization on the quantized coefficients. In addition, the inverse quantized coefficient may be inversely transformed in the inverse transform unit 230 . The inverse transform unit 230 may generate a reconstructed residual block by performing an inverse transform on the inverse quantized coefficient. As a result of performing inverse quantization and inverse transformation on the quantized coefficients, a reconstructed residual block may be generated. At this time, the inverse quantization unit 220 may apply a quantization matrix to the quantized coefficients in generating the reconstructed residual block.

When the intra mode is used, the intra predictor 240 may generate a prediction block by performing spatial prediction using pixel values of previously decoded blocks surrounding the target block.

The inter prediction unit 250 may include a motion compensation unit. Alternatively, the inter prediction unit 250 may be referred to as a motion compensation unit.

When the inter mode is used, the motion compensation unit may generate a prediction block by performing motion compensation using a motion vector and a reference picture stored in the reference picture buffer 270 .

When the motion vector has a non-integer value, the motion compensator may apply an interpolation filter to a partial region in the reference image and generate a prediction block using the reference image to which the interpolation filter is applied. The motion compensation unit may determine which mode among skip mode, merge mode, AMVP mode, and current picture reference mode is a motion compensation method used for a PU included in a CU based on the CU to perform motion compensation, and the determined mode Accordingly, motion compensation may be performed.

The reconstructed residual block and the predicted block may be added through an adder 255. Adder 255 may produce a reconstructed block by adding the reconstructed residual block and the prediction block.

The reconstructed block may pass through the filter unit 260 . The filter unit 260 may apply at least one of a deblocking filter, SAO, and ALF to a reconstructed block or a reconstructed picture.

The reconstructed block that has passed through the filter unit 260 may be stored in the reference picture buffer 270 . A reconstructed block that has passed through the filter unit 260 may be part of a reference picture. In other words, the reference image may be an image composed of reconstructed blocks that have passed through the filter unit 260 . The stored reference image can then be used for inter prediction.

3 is a diagram schematically illustrating a division structure of an image when encoding and decoding an image.

3 may schematically show an example in which one unit is divided into a plurality of sub-units.

In order to efficiently segment an image, a coding unit (CU) may be used in encoding and decoding. A unit may be a term that collectively refers to 1) a block including video samples and 2) a syntax element. For example, “division of a unit” may mean “division of a block corresponding to a unit”.

A CU may be used as a base unit for image encoding/decoding. In addition, the CU may be used as a unit to which one of the intra mode and the inter mode is applied in video encoding/decoding. In other words, in video encoding/decoding, it may be determined which mode among the intra mode and the inter mode is to be applied to each CU.

Also, a CU may be a base unit in prediction, transformation, quantization, inverse transformation, inverse quantization, and coding/decoding of transform coefficients.

Referring to FIG. 3 , an image 300 may be sequentially divided into units of a largest coding unit (LCU), and a division structure of the image 300 may be determined according to the LCU. Here, LCU may be used as the same meaning as Coding Tree Unit (CTU).

Division of a unit may mean division of a block corresponding to the unit. The block division information may include depth information about the depth of a unit. Depth information may indicate the number and/or degree of division of a unit. One unit may be hierarchically divided into sub-units with depth information based on a tree structure. Each divided sub-unit may have depth information. Depth information may be information indicating the size of a CU. Depth information may be stored for each CU. Each CU may have depth information.

The division structure may refer to a distribution of CUs in the LCU 310 to efficiently encode an image. This distribution may be determined according to whether one CU is to be divided into a plurality of CUs. The number of divided CUs may be a positive integer greater than or equal to 2, including 2, 3, 4, 8 and 16, and the like. The horizontal and vertical sizes of the CU generated by division may be smaller than the horizontal and vertical sizes of the CU before division, depending on the number of CUs generated by division.

A divided CU may be recursively divided into a plurality of CUs in the same way. By recursive division, at least one of the horizontal size and the vertical size of the divided CU may be reduced compared to at least one of the horizontal and vertical sizes of the CU before division.

The division of the CU may be made recursively to a predefined depth or to a predefined size. For example, the depth of the LCU may be 0, and the depth of the smallest coding unit (SCU) may be a predefined maximum depth. Here, the LCU may be a CU having the largest coding unit size as described above, and the SCU may be a CU having the smallest coding unit size.

The division may start from the LCU 310, and the depth of the CU may increase by 1 whenever the horizontal size and/or the vertical size of the CU are reduced by the division.

For example, for each depth, a CU that is not split may have a size of 2Nx2N. In addition, in the case of a CU to be divided, a CU of 2Nx2N size may be divided into 4 CUs having a size of NxN. The size of N can be halved every time the depth increases by 1.

Referring to FIG. 3 , an LCU having a depth of 0 may be 64x64 pixels or a 64x64 block. 0 may be the minimum depth. A SCU with a depth of 3 can be 8x8 pixels or an 8x8 block. 3 may be the maximum depth. In this case, the CU of the 64x64 block, which is the LCU, may be expressed as a depth of 0. A CU of a 32x32 block can be represented with a depth of 1. A CU of a 16x16 block can be represented with a depth of 2. A CU of an 8x8 block, which is an SCU, can be expressed as a depth of 3.

Information on whether the CU is split may be expressed through split information of the CU. The division information may be 1 bit of information. All CUs except for the SCU may include partition information. For example, the value of split information of a CU that is not split may be 0, and the value of split information of a CU that is split may be 1.

For example, when one CU is divided into 4 CUs, the horizontal and vertical sizes of each CU of the 4 CUs generated by the division are half of the horizontal size and half of the vertical size of the CU before the division, respectively. can When a 32x32 CU is divided into 4 CUs, the sizes of the 4 CUs may be 16x16. When one CU is divided into 4 CUs, it can be said that the CU is divided in a quad-tree form.

For example, when one CU is split into two CUs, the horizontal size or vertical size of each CU of the two CUs generated by the split is half of the horizontal size or half of the vertical size of the CU before the split, respectively. can When a CU of 32x32 size is vertically divided into two CUs, the sizes of the two divided CUs may be 16x32. When one CU is divided into two CUs, it can be said that the CU is divided in a binary-tree form.

In addition to quad-tree partitioning, and binary-tree partitioning may be applied to the LCU 310 .

4 is a diagram illustrating a form of a prediction unit (PU) that may be included in a coding unit (CU).

Among the CUs divided from the LCU, a CU that is not further divided may be divided into one or more prediction units (PUs).

A PU may be a base unit for prediction. A PU may be coded and decoded in any one of skip mode, inter mode, and intra mode. A PU may be divided into various types according to each mode. For example, the target block described above with reference to FIG. 1 and the target block described above with reference to FIG. 2 may be PUs.

In skip mode, there may not be a split within a CU. In the skip mode, a 2Nx2N mode 410 in which sizes of PU and CU are the same may be supported without division.

In inter mode, 8 divided types can be supported within the CU. For example, in inter mode, 2Nx2N mode 410, 2NxN mode 415, Nx2N mode 420, NxN mode 425, 2NxnU mode 430, 2NxnD mode 435, nLx2N mode 440 and nRx2N Mode 445 may be supported.

In the intra mode, 2Nx2N mode 410 and NxN mode 425, and 2NxN mode and Nx2N may be supported.

In the 2Nx2N mode 410, a PU having a size of 2Nx2N may be encoded. A PU having a size of 2Nx2N may mean a PU having the same size as that of a CU. For example, a 2Nx2N PU may have a size of 64x64, 32x32, 16x16 or 8x8.

In the NxN mode 425, a PU having a size of NxN may be encoded.

For example, in intra prediction, when the size of a PU is 8x8, 4 divided PUs can be coded. The size of the divided PU may be 4x4.

When a PU is coded using an intra mode, the PU may be coded using one intra prediction mode among a plurality of intra prediction modes. For example, High Efficiency Video Coding (HEVC) technology may provide 35 intra prediction modes, and a PU may be coded in one intra prediction mode among the 35 intra prediction modes.

Which mode among the 2Nx2N mode 410 and the NxN mode 425 the PU will be encoded may be determined by a rate-distortion cost.

The encoding apparatus 100 may perform an encoding operation on a PU having a size of 2Nx2N. Here, the encoding operation may be encoding a PU in each of a plurality of intra prediction modes usable by the encoding apparatus 100 . An optimal intra prediction mode for a PU having a size of 2Nx2N may be derived through an encoding operation. An optimal intra prediction mode may be an intra prediction mode that generates a minimum rate-distortion cost for encoding a 2Nx2N PU among a plurality of intra prediction modes usable by the encoding apparatus 100 .

Also, the encoding apparatus 100 may sequentially perform an encoding operation on each PU of NxN-divided PUs. Here, the encoding operation may be encoding a PU in each of a plurality of intra prediction modes usable by the encoding apparatus 100 . An optimal intra prediction mode for an NxN-sized PU may be derived through an encoding operation. An optimal intra-prediction mode may be an intra-prediction mode that generates the minimum rate-distortion cost for encoding an NxN-sized PU among a plurality of intra-prediction modes usable by the encoding apparatus 100.

5 is a diagram illustrating a form of a transform unit (TU) that may be included in a coding unit (CU).

A transform unit (TU) may be a base unit used for processes of transform, quantization, inverse transform, inverse quantization, entropy encoding, and entropy decoding within the CU. A TU may have a square shape or a rectangular shape.

Among the CUs split from the LCU, a CU that is no longer split into CUs may be split into one or more TUs. In this case, the division structure of the TU may be a quad-tree structure. For example, as shown in FIG. 5 , one CU 510 may be divided one or more times according to a quad-tree structure. Through division, one CU 510 may be composed of TUs of various sizes.

In the coding apparatus 100, a 64x64 coding tree unit (CTU) may be divided into a plurality of smaller CUs by a recursive quad-tree structure. One CU can be divided into 4 CUs with equal sizes. CUs can be partitioned recursively, and each CU can have a quad-tree structure.

A CU may have depth. When a CU is split, CUs generated by splitting may have a depth increased by 1 from the depth of the split CU.

For example, the depth of CU may have a value of 0 to 3. The size of the CU may range from 64x64 to 8x8 depending on the depth of the CU.

Through recursive segmentation on the CU, an optimal segmentation method that results in the smallest rate-distortion ratio can be selected.

6 is a diagram for explaining an embodiment of an intra prediction process.

Arrows extending from the center to the periphery of the graph of FIG. 6 may represent prediction directions of intra prediction modes. Also, numbers displayed adjacent to arrows may represent examples of mode values assigned to an intra prediction mode or a prediction direction of the intra prediction mode.

Intra encoding and/or decoding may be performed using reference samples of units adjacent to the target block. Neighboring blocks may be neighboring reconstructed blocks. For example, intra coding and/or decoding may be performed using values of reference samples or coding parameters included in neighboring reconstructed blocks.

The encoding apparatus 100 and/or the decoding apparatus 200 may generate a prediction block by performing intra prediction on the target block based on sample information in the target image. When performing intra prediction, the encoding apparatus 100 and/or the decoding apparatus 200 may generate a prediction block for a target block by performing intra prediction based on sample information in a target image. When intra prediction is performed, the encoding device 100 and/or the decoding device 200 may perform directional prediction and/or non-directional prediction based on at least one reconstructed reference sample.

A prediction block may refer to a block generated as a result of performing intra prediction. A prediction block may correspond to at least one of CU, PU, and TU.

A unit of a prediction block may be the size of at least one of CU, PU, and TU. The prediction block may have a square shape with a size of 2Nx2N or NxN. The size of NxN may include 4x4, 8x8, 16x16, 32x32, and 64x64.

Alternatively, the prediction block may be a rectangular block having an MxN size such as 2x8, 4x8, 2x16, 4x16, and 8x16.

Intra prediction may be performed according to an intra prediction mode for a target block. The number of intra prediction modes that the target block may have may be a predefined fixed value or may be a value determined differently according to properties of the prediction block. For example, the properties of the prediction block may include the size of the prediction block and the type of the prediction block.

For example, the number of intra prediction modes may be fixed to 35 regardless of the size of a prediction block. Alternatively, for example, the number of intra prediction modes may be 3, 5, 9, 17, 34, 35, or 36.

The intra prediction mode may be a non-directional mode or a directional mode. For example, the intra prediction mode may include 2 non-directional modes and 33 directional modes as shown in FIG. 6 .

The non-directional mode may include a DC mode and a planar mode. For example, the mode value of the DC mode may be 1. The mode value of the planner mode may be 0.

Directional modes may be prediction modes having a specific direction or specific angle. Modes other than the DC mode and the planner mode among the plurality of intra prediction modes may be directional modes.

The intra prediction mode may be expressed as at least one of a mode number, a mode value, a mode number, and a mode angle. The number of intra prediction modes may be M. M may be 1 or more. In other words, the number of intra prediction modes may be M including the number of non-directional modes and the number of directional modes.

The number of intra prediction modes may be fixed to M regardless of the block size. Alternatively, the number of intra prediction modes may be different according to the size of a block and/or the type of a color component. For example, the number of prediction modes may be different depending on whether the color component is a luma signal or a chroma signal. For example, as the block size increases, the number of intra prediction modes may increase. Alternatively, the number of intra prediction modes of the luma component block may be greater than the number of intra prediction modes of the chrominance component block.

For example, in the case of a vertical mode having a mode value of 26, prediction may be performed in a vertical direction based on a pixel value of a reference sample.

Even in a directional mode other than the aforementioned mode, the encoding apparatus 100 and the decoding apparatus 200 may perform intra prediction on a target unit using a reference sample according to an angle corresponding to the directional mode.

An intra prediction mode positioned to the right of the vertical mode may be named a vertical-right mode. An intra-prediction mode positioned below the horizontal mode may be named a horizontal-below mode. For example, in FIG. 6 , intra prediction modes having a mode value of 27, 28, 29, 30, 31, 32, 33, and 34 may be vertical right modes 613. Intra prediction modes having a mode value of one of 2, 3, 4, 5, 6, 7, 8, and 9 may be horizontal bottom modes 616 .

The number of intra prediction modes and the mode value of each intra prediction mode described above may be merely illustrative. The number of the aforementioned intra prediction modes and the mode value of each intra prediction mode may be differently defined according to embodiments, implementations, and/or needs.

In order to perform intra prediction on the target block, a step of checking whether samples included in the reconstructed neighboring blocks can be used as reference samples of the target block may be performed. If there is a sample that cannot be used as a reference sample of the current block among the samples of the neighboring block, a value generated by copying and/or interpolation using at least one sample value among the samples included in the reconstructed neighboring block is A sample value of a sample not available as a reference sample may be substituted. If a value generated by copying and/or interpolation is replaced with a sample value of a sample, the sample may be used as a reference sample of the target block.

In intra prediction, a filter may be applied to at least one of a reference sample and a prediction sample based on at least one of an intra prediction mode and a size of a target block.

When the intra prediction mode is the planner mode, in generating the prediction block of the target block, the upper reference sample of the target sample, the left reference sample of the target sample, and the upper right reference sample of the target block according to the location of the prediction target sample in the prediction block. A sample value of the prediction target sample may be generated using a weight-sum of the lower left reference sample of the target block.

When the intra prediction mode is the DC mode, an average value of upper reference samples and left reference samples of the target block may be used to generate a prediction block of the target block.

When the intra prediction mode is a directional mode, a prediction block may be generated using an upper reference sample, a left reference sample, an upper right reference sample, and/or a lower left reference sample of the target block.

Interpolation in units of real numbers may be performed to generate the prediction samples described above.

The intra prediction mode of the target block may be predicted from intra prediction of neighboring blocks of the target block, and information used for prediction may be entropy encoded/decoded.

For example, if the intra prediction modes of the target block and the neighboring blocks are the same, it may be signaled that the intra prediction modes of the target block and the neighboring blocks are the same using a predefined flag.

For example, an indicator indicating an intra prediction mode identical to that of a target block among intra prediction modes of a plurality of neighboring blocks may be signaled.

If the intra prediction modes of the target block and the neighboring blocks are different from each other, entropy encoding/decoding of intra prediction mode information of the target block may be performed based on the intra prediction modes of the neighboring blocks.

7 is a diagram for explaining positions of reference samples used in an intra prediction process.

7 shows locations of reference samples used for intra prediction of a target block. Referring to FIG. 7 , reconstructed reference samples used for intra prediction of a target block include below-left reference samples 731, left reference samples 733, and above-left reference samples 731. left) corner reference sample 735, above reference samples 737 and above-right reference samples 739, and the like.

For example, the left reference samples 733 may refer to reconstructed reference pixels adjacent to the left side of the target block. The top reference samples 737 may refer to reconstructed reference pixels adjacent to the top of the target block. The top-left corner reference sample 735 may mean a reconstructed reference pixel located at the top-left corner of the target block. Also, the lower left reference samples 731 may refer to a reference sample located at the lower end of the left sample line among samples located on the same line as the left sample line composed of the left reference samples 733 . The upper right reference samples 739 may refer to reference samples located on the right side of the upper pixel line among samples located on the same line as the upper sample line composed of the upper reference samples 737 .

When the size of the target block is NxN, each of the lower left reference samples 731, the left reference samples 733, the upper reference samples 737, and the upper right reference samples 739 may be N.

A prediction block may be generated through intra prediction of the target block. Generation of the prediction block may include determining values of pixels of the prediction block. The size of the target block and the prediction block may be the same.

Reference samples used for intra prediction of the target block may vary according to the intra prediction mode of the target block. A direction of an intra prediction mode may represent a dependency relationship between reference samples and pixels of a prediction block. For example, a value of a specified reference sample may be used as a value of one or more specified pixels of a prediction block. In this case, the specified reference sample and the specified one or more pixels of the prediction block may be samples and pixels specified as a straight line in the direction of the intra prediction mode. In other words, the value of the specified reference sample may be copied to a value of a pixel located in a direction opposite to the direction of the intra prediction mode. Alternatively, the value of a pixel of the prediction block may be a value of a reference sample located in the direction of the intra prediction mode based on the position of the pixel.

For example, when the intra prediction mode of the target block is a vertical mode having a mode value of 26, upper reference samples 737 may be used for intra prediction. When the intra prediction mode is a vertical mode, a value of a pixel of a prediction block may be a value of a reference sample positioned vertically above the position of the pixel. Accordingly, top reference samples 737 top adjacent to the target block may be used for intra prediction. Also, values of pixels in one row of the prediction block may be the same as values of upper reference samples 737 .

For example, when the mode value of the intra prediction mode of the target block is 18, at least some of the left reference samples 733, the upper left corner reference sample 735, and the upper reference samples 737 are used for intra prediction. can be used When the mode value of the intra prediction mode is 18, the value of a pixel of the prediction block may be a value of a reference sample located diagonally to the top left of the pixel.

The number of reference samples used to determine the pixel value of one pixel of the prediction block may be one or two or more.

As described above, a pixel value of a pixel of a prediction block may be determined according to the position of the pixel and the position of the reference sample indicated by the direction of the intra prediction mode. When the position of the reference sample indicated by the position of the pixel and the direction of the intra prediction mode is an integer position, a value of one reference sample indicated by the integer position may be used to determine a pixel value of a pixel of the prediction block.

When the position of the reference sample indicated by the position of the pixel and the direction of the intra prediction mode is not an integer position, an interpolated reference sample may be generated based on two reference samples closest to the position of the reference sample. there is. The value of the interpolated reference sample may be used to determine a pixel value of a pixel of the predictive block. In other words, when the location of a pixel of the prediction block and the location of a reference sample indicated by the direction of the intra prediction mode indicate a gap between two reference samples, an interpolated value will be generated based on the values of the two samples. can

A prediction block generated by prediction may not be the same as the original target block. In other words, a prediction error, which is a difference between a target block and a prediction block, may exist, and a prediction error may also exist between pixels of the target block and pixels of the prediction block.

Hereinafter, the terms “difference”, “error” and “residual” may be used interchangeably and interchangeably.

For example, in the case of directional intra prediction, a larger prediction error may occur as the distance between a pixel of a prediction block and a reference sample increases. A discontinuity may occur between a prediction block generated by such a prediction error and the like and neighboring blocks.

Filtering of prediction blocks may be used to reduce prediction errors. Filtering may be adaptively applying a filter to a region considered to have a large prediction error among prediction blocks. For example, a region considered to have a large prediction error may be a boundary of a prediction block. Also, depending on the intra-prediction mode, a region considered to have a large prediction error among prediction blocks may be different, and filter characteristics may be different.

8 is a diagram for explaining an embodiment of an inter prediction process.

A rectangle shown in FIG. 8 may represent an image (or picture). Also, arrows in FIG. 8 may indicate prediction directions. That is, an image may be encoded and/or decoded according to a prediction direction.

Each image may be classified into an intra picture (I picture), a uni-prediction picture (P picture), and a bi-prediction picture (B picture) according to an encoding type. Each picture may be coded according to the coding type of each picture.

When a target image to be encoded is an I-picture, the target image may be encoded using data within the image itself without inter prediction referring to another image. For example, an I picture can be coded only with intra prediction.

When the target image is a P picture, the target image may be coded through inter prediction using only reference pictures existing in one direction. Here, the unidirectional direction may be a forward direction or a reverse direction.

When the target video is a B picture, the target video may be coded through inter prediction using reference pictures existing in both directions or inter prediction using reference pictures existing in one of forward and backward directions. Here, both directions may be forward and reverse directions.

P-pictures and B-pictures that are coded and/or decoded using reference pictures may be regarded as pictures in which inter prediction is used.

Below, inter prediction in inter mode according to an embodiment is described in detail.

Inter prediction may be performed using motion information.

In the inter mode, the encoding apparatus 100 may perform inter prediction and/or motion compensation on a target block. The decoding apparatus 200 may perform inter prediction and/or motion compensation corresponding to inter prediction and/or motion compensation performed in the encoding apparatus 100 on a target block.

Motion information on the target block may be derived during inter prediction by each of the encoding apparatus 100 and the decoding apparatus 200 . The motion information may be derived using motion information of a reconstructed neighboring block, motion information of a collocated block (col block), and/or motion information of a block adjacent to the collocated block. A collocated block may be a block in an already reconstructed collocated picture (col picture). A position of a collocated block in a collocated picture may correspond to a position of a target block in a target image. A collocated picture may be one of at least one reference picture included in a reference picture list.

For example, the encoding apparatus 100 or the decoding apparatus 200 performs prediction and/or motion compensation by using motion information of a spatial candidate and/or a temporal candidate as motion information of a target block. can be done A target block may mean a PU and/or a PU partition.

A spatial candidate may be a reconstructed block that is spatially adjacent to the target block.

A temporal candidate may be a reconstructed block corresponding to a target block in an already reconstructed collocated picture (col picture).

In inter prediction, the encoding apparatus 100 and the decoding apparatus 200 may improve encoding efficiency and decoding efficiency by using motion information of spatial candidates and/or temporal candidates. Motion information of spatial candidates may be referred to as spatial motion information. Motion information of temporal candidates may be referred to as temporal motion information.

Hereinafter, motion information of a spatial candidate may be motion information of a PU including the spatial candidate. Motion information of the temporal candidate may be motion information of a PU including the temporal candidate. Motion information of the candidate block may be motion information of a PU including the candidate block.

Inter prediction may be performed using a reference picture.

A reference picture may be at least one of a previous picture of the target picture or a subsequent picture of the target picture. A reference picture may refer to an image used for prediction of a target block.

In inter prediction, a region within a reference picture may be specified by using a reference picture index (or refIdx) indicating a reference picture and a motion vector to be described later. Here, a specified region within a reference picture may represent a reference block.

Inter prediction may select a reference picture and may select a reference block corresponding to a target block within the reference picture. In addition, inter prediction may generate a prediction block for a target block using the selected reference block.

Motion information may be derived during inter prediction by each of the encoding apparatus 100 and the decoding apparatus 200 .

A spatial candidate may be a block that 1) exists in the target picture, 2) has already been reconstructed through encoding and/or decoding, and 3) is located adjacent to or at a corner of the target block. Here, the block located at the corner of the target block may be a block vertically adjacent to a neighboring block horizontally adjacent to the target block or a block horizontally adjacent to a neighboring block vertically adjacent to the target block. "A block located at a corner of a target block" may have the same meaning as "a block adjacent to a corner of a target block". A "block located at a corner of a target block" may be included in a "block adjacent to the target block".

For example, spatial candidates include a reconstructed block located to the left of the target block, a reconstructed block located on top of the target block, a reconstructed block located at the lower left corner of the target block, and a reconstructed block located at the upper right corner of the target block. It can be a reconstructed block or a reconstructed block located in the upper left corner of the target block.

Each of the encoding apparatus 100 and the decoding apparatus 200 may identify a block existing at a position spatially corresponding to a target block within a col picture. A position of a target block in a target picture and a position of an identified block in a collocated picture may correspond to each other.

Each of the encoding apparatus 100 and the decoding apparatus 200 may determine a col block existing at a predefined relative position with respect to the identified block as a temporal candidate. The predefined relative position may be a position inside and/or outside the identified block.

For example, the collocated block may include a first collocated block and a second collocated block. When the coordinates of the identified block are (xP, yP) and the size of the identified block is (nPSW, nPSH), the first collocated block may be a block located at the coordinates (xP + nPSW, yP + nPSH). The second collocated block may be a block located at coordinates (xP + (nPSW >> 1), yP + (nPSH >> 1). The second call block may be selectively used when the first call block is unavailable.

The motion vector of the target block may be determined based on the motion vector of the collocated block. Each of the encoding apparatus 100 and the decoding apparatus 200 may scale a motion vector of a collocated block. A scaled motion vector of the collocated block may be used as a motion vector of the target block. Also, a motion vector of motion information of a temporal candidate stored in the list may be a scaled motion vector.

A ratio of the motion vector of the target block and the motion vector of the collocated block may be equal to the ratio of the first distance and the second distance. The first distance may be the distance between the reference picture of the target block and the target picture. The second distance may be the distance between the reference picture of the collocated block and the collocated picture.

A method of deriving motion information may change according to an inter prediction mode of a target block. For example, inter prediction modes applied for inter prediction may include an Advanced Motion Vector Predictor (AMVP) mode, a merge mode, a skip mode, a current picture reference mode, and the like. there is. Merge mode may also be referred to as motion merge mode. Below, each of the modes is described in detail.

1) AMVP mode

When the AMVP mode is used, the encoding apparatus 100 may search for similar blocks in the vicinity of the target block. The encoding apparatus 100 may obtain a prediction block by performing prediction on a target block using motion information of a similar block found. The encoding apparatus 100 may encode a residual block that is a difference between a target block and a prediction block.

1-1) Creating a predicted motion vector candidate list

When the AMVP mode is used as the prediction mode, each of the encoding apparatus 100 and the decoding apparatus 200 may generate a predictive motion vector candidate list using a motion vector of a spatial candidate, a motion vector of a temporal candidate, and a zero vector. there is. The predicted motion vector candidate list may include one or more predicted motion vector candidates. At least one of the motion vector of the motion vector of the spatial candidate, the motion vector of the temporal candidate, and the zero vector may be determined and used as the predictive motion vector candidate.

Hereinafter, the terms “predicted motion vector (candidate)” and “motion vector (candidate)” may be used interchangeably and may be used interchangeably.

A spatial motion candidate may include a reconstructed spatial neighboring block. In other words, the motion vectors of the reconstructed neighboring blocks may be referred to as spatial prediction motion vector candidates.

Temporal motion candidates may include a collocated block and blocks adjacent to the collocated block. In other words, a motion vector of a collocated block or a motion vector of a block adjacent to the collocated block may be referred to as a temporal prediction motion vector candidate.

The zero vector may be a (0, 0) motion vector.

The predictive motion vector candidate may be a motion vector predictor for motion vector prediction. Also, in the encoding apparatus 100, the predicted motion vector candidate may be an initial motion vector search position.

1-2) Motion vector search using a predictive motion vector candidate list

The encoding apparatus 100 may determine a motion vector to be used for encoding a target block within a search range by using the predictive motion vector candidate list. Also, the encoding apparatus 100 may determine a predictive motion vector candidate to be used as a predictive motion vector of the target block from among predictive motion vector candidates in the predictive motion vector candidate list.

A motion vector to be used for encoding a target block may be a motion vector that can be encoded with minimal cost.

Also, the encoding apparatus 100 may determine whether to use the AMVP mode in encoding the target block.

1-3) Transmission of inter prediction information

The encoding apparatus 100 may generate a bitstream including inter prediction information required for inter prediction. The decoding apparatus 200 may perform inter prediction on a target block using inter prediction information of a bitstream.

The inter-prediction information includes 1) mode information indicating whether the AMVP mode is used, 2) predicted motion vector index, 3) motion vector difference (MVD), 4) reference direction, and 5) reference picture index. can do.

Also, the inter prediction information may include a residual signal.

When the mode information indicates that the AMVP mode is used, the decoding apparatus 200 may obtain a predicted motion vector index, a motion vector difference, a reference direction, and a reference picture index from a bitstream through entropy decoding.

The predictive motion vector index may indicate a predictive motion vector candidate used for prediction of a target block among predictive motion vector candidates included in the predictive motion vector candidate list.

1-4) Inter prediction of AMVP mode using inter prediction information

The decoding apparatus 200 may derive a predicted motion vector candidate using the predicted motion vector candidate list, and may determine motion information of a target block based on the derived motion vector predicted candidate.

The decoding apparatus 200 may determine a motion vector candidate for a target block from among motion vector predictor candidates included in a predictor motion vector candidate list by using the predictor motion vector index. The decoding apparatus 200 may select a predicted motion vector candidate indicated by a predicted motion vector index as a predicted motion vector of a target block from among motion vector predicted candidates included in the predicted motion vector candidate list.

A motion vector actually used for inter prediction of a target block may not coincide with a predicted motion vector. MVD may be used to represent a difference between a motion vector actually used for inter prediction of a target block and a predicted motion vector. The encoding apparatus 100 may derive a predicted motion vector similar to a motion vector actually used for inter prediction of a target block in order to use an MVD having a size as small as possible.

MVD may be a difference between a motion vector of a target block and a predicted motion vector. The encoding apparatus 100 may calculate the MVD and entropy-encode the MVD.

The MVD may be transmitted from the encoding device 100 to the decoding device 200 through a bitstream. The decoding apparatus 200 may decode the received MVD. The decoding apparatus 200 may derive the motion vector of the target block by adding the decoded MVD and the predicted motion vector. In other words, the motion vector of the target block derived by the decoding apparatus 200 may be the sum of the entropy-decoded MVD and the motion vector candidate.

A reference direction may indicate a reference picture list used for prediction of a target block. For example, the reference direction may indicate one of a reference picture list L0 and a reference picture list L1.

The reference direction indicates only a reference picture list used for prediction of the target block, and may not indicate that directions of reference pictures are limited to a forward direction or a backward direction. In other words, each of the reference picture list L0 and the reference picture list L1 may include forward and/or backward pictures.

That the reference direction is uni-direction may mean that one reference picture list is used. Bi-direction of the reference direction may mean that two reference picture lists are used. In other words, the reference direction can indicate one of: that only the reference picture list L0 is used, that only the reference picture list L1 is used, and two reference picture lists.

The reference picture index may indicate a reference picture used for prediction of a target block among reference pictures of a reference picture list. The reference picture index may be entropy-coded by the encoding apparatus 100. The entropy-encoded reference picture index may be signaled from the encoding device 100 to the decoding device 200 through a bitstream.

When two reference picture lists are used for prediction of a target block. One reference picture index and one motion vector may be used for each reference picture list. Also, when two reference picture lists are used for prediction of a target block, two prediction blocks may be specified for the target block. For example, a (final) prediction block of the target block may be generated through an average or a weighted-sum of two prediction blocks of the target block.

The motion vector of the target block may be derived by the predicted motion vector index, MVD, reference direction, and reference picture index.

The decoding apparatus 200 may generate a prediction block for the target block based on the derived motion vector and the reference picture index. For example, the prediction block may be a reference block indicated by a derived motion vector in a reference picture indicated by a reference picture index.

By encoding the predicted motion vector index and the MVD without encoding the motion vector of the target block, the amount of bits transmitted from the encoding apparatus 100 to the decoding apparatus 200 can be reduced and encoding efficiency can be improved.

Motion information of neighboring blocks reconstructed with respect to the target block may be used. In a specific inter-prediction mode, the encoding apparatus 100 may not separately encode the motion information of the target block itself. Motion information of the target block is not encoded, and other information capable of inducing motion information of the target block through motion information of reconstructed neighboring blocks may be encoded instead. As other information is encoded instead, the amount of bits transmitted to the decoding apparatus 200 can be reduced and encoding efficiency can be improved.

For example, as an inter prediction mode in which motion information of the target block is not directly encoded, there may be a skip mode and/or a merge mode. In this case, the encoding apparatus 100 and the decoding apparatus 200 may use an identifier and/or an index indicating which unit of the reconstructed neighboring units motion information is used as the motion information of the target unit.

2) Merge Mode

As a method of deriving motion information of a target block, there is a merge. Merge may refer to merging of motions of a plurality of blocks. Merge may mean applying motion information of one block to another block as well. In other words, merge mode may refer to a mode in which motion information of a target block is derived from motion information of neighboring blocks.

When merge mode is used, the encoding apparatus 100 may perform prediction of motion information of a target block by using motion information of a spatial candidate and/or motion information of a temporal candidate. The spatial candidate may include reconstructed spatial neighboring blocks spatially adjacent to the target block. The spatially adjacent blocks may include a left adjacent block and a top adjacent block. Temporal candidates may include call blocks. The terms "spatial candidate" and "spatial merge candidate" may be used interchangeably and may be used interchangeably. The terms "temporal candidate" and "temporal merge candidate" may be used interchangeably and may be used interchangeably.

The encoding apparatus 100 may obtain a prediction block through prediction. The encoding apparatus 100 may encode a residual block that is a difference between a target block and a prediction block.

2-1) Creating a merge candidate list

When the merge mode is used, each of the encoding apparatus 100 and the decoding apparatus 200 may generate a merge candidate list using motion information of spatial candidates and/or motion information of temporal candidates. Motion information may include 1) a motion vector, 2) a reference picture index, and 3) a reference direction. The reference direction can be unidirectional or bidirectional.

The merge candidate list may include merge candidates. A merge candidate may be motion information. In other words, the merge candidate list may be a list in which motion information is stored.

Merge candidates may be motion information such as temporal candidates and/or spatial candidates. Also, the merge candidate list may include a new merge candidate generated by a combination of merge candidates already existing in the merge candidate list. In other words, the merge candidate list may include new motion information generated by combining motion information already existing in the merge candidate list.

Also, the merge candidate list may include motion information of a zero vector. A zero vector may be referred to as a zero merge candidate.

In other words, the motion information in the merge candidate list is: 1) motion information of a spatial candidate, 2) motion information of a temporal candidate, 3) motion information generated by a combination of motion information already existing in the merge candidate list, 4) zero vector may be at least one of

Motion information may include 1) a motion vector, 2) a reference picture index, and 3) a reference direction. A reference direction may be referred to as an inter prediction indicator. The reference direction can be unidirectional or bidirectional. A unidirectional reference direction may represent L0 prediction or L1 prediction.

The merge candidate list may be generated before prediction by merge mode is performed.

The number of merge candidates in the merge candidate list may be predefined. The encoding device 100 and the decoding device 200 may add merge candidates to the merge candidate list according to a predefined method and a predefined order so that the merge candidate list includes a predefined number of merge candidates. The merge candidate list of the encoding device 100 and the merge candidate list of the decoding device 200 may be the same through a predefined method and a predefined ranking.

Merge may be applied in units of CUs or units of PUs. When merging is performed in units of CUs or PUs, the encoding apparatus 100 may transmit a bitstream including predefined information to the decoding apparatus 200. For example, the predefined information includes 1) information indicating whether merging is to be performed for each block partition, 2) which block to merge with among blocks that are spatial candidates and/or temporal candidates for the target block. It may contain information on whether

2-2) Motion vector search using merge candidate list

The encoding apparatus 100 may determine a merge candidate to be used for encoding a target block. For example, the encoding apparatus 100 may perform predictions on a target block using merge candidates of the merge candidate list and generate residual blocks for the merge candidates. The encoding apparatus 100 may use a merge candidate requiring a minimum cost in prediction and encoding of a residual block for encoding a target block.

Also, the encoding apparatus 100 may determine whether to use merge mode in encoding a target block.

2-3) Transmission of inter prediction information

The encoding apparatus 100 may generate a bitstream including inter prediction information required for inter prediction. The encoding apparatus 100 may generate entropy-encoded inter-prediction information by performing entropy encoding on the inter-prediction information, and may transmit a bitstream including the entropy-encoded inter-prediction information to the decoding apparatus 200. Entropy-encoded inter prediction information may be signaled from the encoding apparatus 100 to the decoding apparatus 200 through a bitstream.

The decoding apparatus 200 may perform inter prediction on a target block using inter prediction information of a bitstream.

The inter prediction information may include 1) mode information indicating whether merge mode is used and 2) merge index.

Also, the inter prediction information may include a residual signal.

The decoding apparatus 200 may obtain the merge index from the bitstream only when the mode information indicates that the merge mode is used.

Mode information may be a merge flag. A unit of mode information may be a block. Information about a block may include mode information, and the mode information may indicate whether merge mode is applied to the block.

The merge index may indicate a merge candidate used for prediction of a target block among merge candidates included in the merge candidate list. Alternatively, the merge index may indicate which block among neighboring blocks spatially or temporally adjacent to the target block is merged with.

2-4) Inter prediction of merge mode using inter prediction information

The decoding apparatus 200 may perform prediction on a target block by using a merge candidate indicated by a merge index among merge candidates included in the merge candidate list.

The motion vector of the target block may be specified by the motion vector of the merge candidate indicated by the merge index, the reference picture index, and the reference direction.

3) Skip Mode

The skip mode may be a mode in which motion information of a spatial candidate or motion information of a temporal candidate is applied to a target block as it is. Also, the skip mode may be a mode in which residual signals are not used. That is to say, when skip mode is used, the reconstructed block may be a predictive block.

A difference between merge mode and skip mode may be transmission or use of residual signals. In other words, skip mode may be similar to merge mode except that residual signals are not transmitted or used.

When the skip mode is used, the encoding apparatus 100 transmits information indicating which block's motion information among spatial or temporal candidate blocks is used as the motion information of the target block to the decoding apparatus 200 through a bitstream. can transmit The encoding apparatus 100 may generate entropy-encoded information by performing entropy encoding on such information, and may signal the entropy-encoded information to the decoding apparatus 200 through a bitstream.

Also, when the skip mode is used, the encoding device 100 may not transmit other syntax element information such as MVD to the decoding device 200. For example, when used with the skip mode, the encoding apparatus 100 may not signal syntax elements related to at least one of MVC, coded block flags, and transform coefficient levels to the decoding apparatus 200.

3-1) Creation of merge candidate list

Skip mode can also use a merge candidate list. In other words, the merge candidate list can be used in both merge mode and skip mode. In this regard, the merge candidate list may be referred to as a "skip candidate list" or a "merge/skip candidate list".

Alternatively, skip mode may use a separate candidate list different from merge mode. In this case, in the description below, the merge candidate list and the merge candidate may be replaced with the skip candidate list and the skip candidate, respectively.

The merge candidate list may be generated before prediction by skip mode is performed.

3-2) Motion vector search using merge candidate list

The encoding apparatus 100 may determine a merge candidate to be used for encoding a target block. For example, the encoding apparatus 100 may perform predictions on a target block using merge candidates of a merge candidate list. The encoding apparatus 100 may use a merge candidate requiring a minimum prediction cost for encoding a target block.

Also, the encoding apparatus 100 may determine whether to use a skip mode in encoding a target block.

3-3) Transmission of inter prediction information

The encoding apparatus 100 may generate a bitstream including inter prediction information required for inter prediction. The decoding apparatus 200 may perform inter prediction on a target block using inter prediction information of a bitstream.

The inter-prediction information may include 1) mode information indicating whether a skip mode is used and 2) a skip index.

The skip index may be the same as the aforementioned merge index.

When the skip mode is used, the target block may be coded without a residual signal. Inter prediction information may not include a residual signal. Alternatively, the bitstream may not include a residual signal.

The decoding apparatus 200 may obtain the skip index from the bitstream only when the mode information indicates that the skip mode is used. As mentioned above, the merge index and skip index may be the same. The decoding apparatus 200 may obtain the skip index from the bitstream only when the mode information indicates that merge mode or skip mode is used.

The skip index may indicate a merge candidate used for prediction of a target block among merge candidates included in the merge candidate list.

3-4) Skip Mode Inter Prediction Using Inter Prediction Information

The decoding apparatus 200 may perform prediction on a target block by using a merge candidate indicated by a skip index among merge candidates included in the merge candidate list.

A motion vector of a target block may be specified by a motion vector of a merge candidate indicated by a skip index, a reference picture index, and a reference direction.

4) Current picture reference mode

The current picture reference mode may mean a prediction mode using a pre-reconstructed region in the current picture to which the target block belongs.

A vector for specifying a pre-reconstructed area may be defined. Whether the target block is encoded in the current picture reference mode can be determined using the reference picture index of the target block.

A flag or index indicating whether the target block is a block encoded in the current picture reference mode may be signaled from the encoding apparatus 100 to the decoding apparatus 200. Alternatively, whether the target block is a block coded in the current picture reference mode may be inferred through a reference picture index of the target block.

When the target block is coded in the current picture reference mode, the current picture can be added at a fixed position or an arbitrary position within the reference picture list for the target block.

For example, the fixed position may be a position where the reference picture index is 0 or the last position.

When the current picture is added to an arbitrary position in the reference picture list, a separate reference picture index indicating such an arbitrary position may be signaled from the encoding apparatus 100 to the decoding apparatus 200.

In the aforementioned AMVP mode, merge mode, and skip mode, motion information to be used for prediction of a target block among motion information in the list may be specified through an index of the list.

In order to improve encoding efficiency, the encoding apparatus 100 may signal only the index of an element that causes the least cost in inter prediction of a target block among elements in the list. The encoding device 100 may encode the index and signal the encoded index.

Accordingly, the aforementioned lists (ie, the predicted motion vector candidate list and the merge candidate list) may have to be derived in the same manner based on the same data in the encoding apparatus 100 and the decoding apparatus 200. Here, the same data may include a reconstructed picture and a reconstructed block. Also, in order to specify an element by index, the order of the elements within the list may need to be constant.

9 shows spatial candidates according to an example.

In Fig. 9, the positions of spatial candidates are shown.

A large block in the middle may represent a target block. Five small blocks may represent spatial candidates.

Coordinates of the target block may be (xP, yP), and the size of the target block may be (nPSW, nPSH).

The spatial candidate A ₀ may be a block adjacent to the lower left corner of the target block. A ₀ may be a block occupying pixels of coordinates (xP - 1, yP + nPSH + 1).

Spatial candidate A ₁ may be a block adjacent to the left of the target block. A ₁ may be the lowest block among blocks adjacent to the left side of the target block. Alternatively, A ₁ may be a block adjacent to the top of A ₀ . A ₁ may be a block occupying pixels of coordinates (xP - 1, yP + nPSH).

Spatial candidate B ₀ may be a block adjacent to the upper right corner of the target block. B ₀ may be a block occupying pixels of coordinates (xP + nPSW + 1, yP - 1).

Spatial candidate B ₁ may be a block adjacent to the top of the target block. B ₁ may be the rightmost block among blocks adjacent to the top of the target block. Alternatively, B ₁ may be a block adjacent to the left side of B ₀ . B ₁ may be a block occupying pixels of coordinates (xP + nPSW, yP - 1).

Spatial candidate B ₂ may be a block adjacent to the upper left corner of the target block. B ₂ may be a block occupying pixels of coordinates (xP - 1, yP - 1).

Determination of the availability of spatial and temporal candidates

In order to include the motion information of the spatial candidate or the motion information of the temporal candidate in the list, it must be determined whether the motion information of the spatial candidate or the motion information of the temporal candidate is available.

Hereinafter, a candidate block may include a spatial candidate and a temporal candidate.

For example, the above determination may be made by sequentially applying steps 1) to 4) below.

Step 1) If the PU including the candidate block is outside the boundary of the picture, the availability of the candidate block may be set to false. "Availability is set to false" may mean the same as "availability is set to unavailability".

Step 2) If the PU including the candidate block is outside the boundary of the slice, the availability of the candidate block may be set to false. If the target block and the candidate block are located in different slices, the availability of the candidate block may be set to false.

Step 3) If the PU including the candidate block is outside the boundary of the tile, the availability of the candidate block may be set to false. If the target block and the candidate block are located in different tiles, the availability of the candidate block may be set to false.

Step 4) If the prediction mode of the PU including the candidate block is an intra prediction mode, availability of the candidate block may be set to false. If the PU containing the candidate block does not use inter prediction, the availability of the candidate block may be set to false.

10 illustrates an order of adding motion information of spatial candidates to a merge list according to an example.

As shown in FIG. 10 , in adding motion information of spatial candidates to the merge list, the order of A ₁ , B ₁ , B ₀ , A ₀ and B ₂ may be used. That is, in the order of A ₁ , B ₁ , B ₀ , A ₀ and B ₂ , motion information of available spatial candidates may be added to the merge list.

Merge list derivation method in merge mode and skip mode

As described above, the maximum number of merge candidates in the merge list may be set. The set maximum number is indicated by N. The set number may be transmitted from the encoding device 100 to the decoding device 200. A slice header of a slice may include N. In other words, the maximum number of merge candidates of the merge list for the target block of the slice may be set by the slice header. For example, the value of N may be 5 by default.

Motion information (ie, merge candidates) may be added to the merge list in the order of steps 1) to 4) below.

Step 1) Available spatial candidates among spatial candidates may be added to the merge list. Motion information of available spatial candidates may be added to the merge list in the order shown in FIG. 10 . In this case, if motion information of an available spatial candidate overlaps with other motion information already existing in the merge list, the motion information may not be added to the merge list. Checking whether it overlaps with other motion information existing in the list can be abbreviated as "redundancy check".

A maximum of N pieces of motion information may be added.

Step 2) If the number of pieces of motion information in the merge list is smaller than N and a temporal candidate is available, the motion information of the temporal candidate may be added to the merge list. In this case, if motion information of an available temporal candidate overlaps with other motion information already existing in the merge list, the motion information may not be added to the merge list.

Step 3) If the number of pieces of motion information in the merge list is smaller than N and the type of the target slice is “B”, the combined motion information generated by combined bi-prediction is added to the merge list. can

The target slice may be a slice including the target block.

The combined motion information may be a combination of L0 motion information and L1 motion information. The L0 motion information may be motion information referring only to the reference picture list L0. The L1 motion information may be motion information referring only to the reference picture list L1.

Within the merge list, there may be one or more L0 motion information. Also, within the merge list, there may be one or more L1 motion information.

The combined motion information may be one or more. In generating the combined motion information, which L0 motion information and which L1 motion information among one or more pieces of L0 motion information and one or more pieces of L1 motion information are to be used may be predefined. One or more pieces of combined motion information may be generated in a predefined order by combined bidirectional prediction using pairs of different pieces of motion information in a merge list. One of the pairs of different motion information may be L0 motion information and the other may be L1 motion information.

For example, the combined motion information added with the highest priority may be a combination of L0 motion information having a merge index of 0 and L1 motion information having a merge index of 1. If the motion information with a merge index of 0 is not L0 motion information or the motion information with a merge index of 1 is not L1 motion information, the combined motion information may not be generated and added. Motion information added next may be a combination of L0 motion information having a merge index of 1 and L1 motion information having a merge index of 0. The following specific combinations may follow other combinations in the field of video encoding/decoding.

In this case, if the combined motion information overlaps with other motion information already existing in the merge list, the combined motion information may not be added to the merge list.

Step 4) If the number of pieces of motion information in the merge list is smaller than N, zero vector motion information may be added to the merge list.

The zero vector motion information may be motion information in which a motion vector is a zero vector.

One or more zero vector motion information may be provided. Reference picture indexes of one or more zero vector motion information may be different from each other. For example, the value of the reference picture index of the first zero vector motion information may be 0. The value of the reference picture index of the second zero vector motion information may be 1.

The number of zero vector motion information may be equal to the number of reference pictures in the reference picture list.

The reference direction of the zero vector motion information may be bidirectional. Both motion vectors may be zero vectors. The number of zero vector motion information may be the smaller of the number of reference pictures in the reference picture list L0 and the number of reference pictures in the reference picture list L1. Alternatively, when the number of reference pictures in the reference picture list L0 and the number of reference pictures in the reference picture list L1 are different from each other, a unidirectional reference direction may be used for a reference picture index applicable to only one reference picture list.

The encoding apparatus 100 and/or the decoding apparatus 200 may sequentially add zero vector motion information to the merge list while changing the reference picture index.

If the zero vector motion information overlaps with other motion information already present in the merge list, the zero vector motion information may not be added to the merge list.

The order of steps 1) to 4) described above is merely exemplary, and the order between steps may be interchanged. Also, some of the steps may be omitted according to predefined conditions.

Derivation method of predictive motion vector candidate list in AMVP mode

The maximum number of motion vector predictor candidates in the predictor motion vector candidate list may be predefined. The predefined maximum number is denoted by N. For example, the predefined maximum number may be 2.

Motion information (ie, predicted motion vector candidates) may be added to the predicted motion vector candidate list in the order of steps 1) to 3) below.

Step 1) Among the spatial candidates, available spatial candidates may be added to the predicted motion vector candidate list. Spatial candidates may include a first spatial candidate and a second spatial candidate.

The first spatial candidate may be one of A ₀ , A ₁ , scaled A ₀ and scaled A ₁ . The second spatial candidate may be one of B ₀ , B ₁ , B ₂ , scaled B ₀ , scaled B ₁ , and scaled B ₂ .

Motion information of available spatial candidates may be added to the predicted motion vector candidate list in the order of the first spatial candidate and the second spatial candidate. In this case, when motion information of an available spatial candidate overlaps with other motion information already existing in the motion vector predictor candidate list, the motion information may not be added to the predictor motion vector candidate list. In other words, when the value of N is 2, if the motion information of the second spatial candidate is identical to the motion information of the first spatial candidate, the motion information of the second spatial candidate may not be added to the predicted motion vector candidate list.

A maximum of N pieces of motion information may be added.

Step 2) If the number of pieces of motion information in the predicted motion vector candidate list is smaller than N and a temporal candidate is available, the motion information of the temporal candidate may be added to the predicted motion vector candidate list. In this case, when motion information of an available temporal candidate overlaps with other motion information already existing in the motion vector predictor candidate list, the motion information may not be added to the predictor motion vector candidate list.

Step 3) If the number of pieces of motion information in the predicted motion vector candidate list is smaller than N, zero vector motion information may be added to the predicted motion vector candidate list.

One or more zero vector motion information may be provided. Reference picture indexes of one or more zero vector motion information may be different from each other.

The encoding apparatus 100 and/or the decoding apparatus 200 may sequentially add zero vector motion information to the predictive motion vector candidate list while changing the reference picture index.

When the zero vector motion information overlaps with other motion information already existing in the predicted motion vector candidate list, the zero vector motion information may not be added to the predicted motion vector candidate list.

The description of the zero vector motion information described above for the merge list can also be applied to the zero vector motion information. Redundant descriptions are omitted.

The order of steps 1) to 3) described above is merely exemplary, and the order between steps may be interchanged. Also, some of the steps may be omitted according to predefined conditions.

11 illustrates a process of transformation and quantization according to an example.

As shown in FIG. 11, a quantized level may be generated by performing a transformation and/or quantization process on the residual signal.

A residual signal may be generated as a difference between an original block and a prediction block. Here, the prediction block may be a block generated by intra prediction or inter prediction.

Transformation may include at least one of a primary transformation and a secondary transformation. A transform coefficient may be generated by performing a primary transform on the residual signal, and a secondary transform coefficient may be generated by performing a secondary transform on the transform coefficient.

The primary transform may be performed using at least one of a plurality of pre-defined transform methods. For example, a plurality of pre-defined transform methods are based on a Discrete Cosine Transform (DCT), a Discrete Sine Transform (DST), and a Karhunen-Loube Transform (KLT). conversion, etc.

A secondary transform may be performed on transform coefficients generated by performing the primary transform.

Transform method(s) applied to the primary transform and/or the secondary transform may be determined according to at least one of coding parameters for the target block and/or neighboring blocks. Alternatively, transformation information indicating a transformation method may be signaled from the encoding device 100 to the decoding device 200.

A quantized level may be generated by performing quantization on a residual signal or a result generated by performing a primary transform and/or a secondary transform.

The quantized level may be scanned according to at least one of an upper-right diagonal scan, a vertical scan, and a horizontal scan according to at least one of an intra prediction mode, a block size, and a block shape.

For example, the coefficients may be changed into a one-dimensional vector form by scanning the coefficients of a block using up-right diagonal scanning. Alternatively, depending on the size of the transform block and/or the intra prediction mode, a vertical scan that scans two-dimensional block-shaped coefficients in the column direction or a horizontal scan that scans two-dimensional block-shaped coefficients in the row direction may be used instead of the upper-right diagonal scan. there is.

The scanned quantization level may be entropy-encoded, and the bitstream may include the entropy-encoded quantization level.

The decoding apparatus 200 may generate a quantized level through entropy decoding on a bitstream. The quantized levels may be aligned in a 2D block form through inverse scanning. At this time, as a reverse scanning method, at least one of an upper right diagonal scan, a vertical scan, and a horizontal scan may be performed.

Inverse quantization may be performed on the quantized level. A secondary inverse transform may be performed on the result generated by performing the inverse quantization, depending on whether or not the secondary inverse transform is performed. In addition, a first-order inverse transform may be performed on a result generated by performing a second-order inverse transform, depending on whether or not the first-order inverse transform is performed. A reconstructed residual signal may be generated by performing a first-order inverse transform on a result generated by performing a second-order inverse transform.

12 is a structural diagram of an encoding device according to an embodiment.

The encoding device 1200 may correspond to the aforementioned encoding device 100.

The encoding device 1200 includes a processing unit 1210, a memory 1230, a user interface (UI) input device 1250, a UI output device 1260, and storage that communicate with each other through a bus 1290. (1240). Also, the encoding device 1200 may further include a communication unit 1220 connected to the network 1299.

The processing unit 1210 may be a semiconductor device that executes processing instructions stored in a central processing unit (CPU), memory 1230 or storage 1240 . The processing unit 1210 may be at least one hardware processor.

The processing unit 1210 may generate and process signals, data, or information input to the encoding device 1200, output from the encoding device 1200, or used inside the encoding device 1200, signals, Inspection, comparison, and judgment related to data or information can be performed. In other words, in an embodiment, generation and processing of data or information, and examination, comparison, and judgment related to the data or information may be performed by the processing unit 1210 .

The processing unit 1210 includes an inter prediction unit 110, an intra prediction unit 120, a switch 115, a subtractor 125, a transform unit 130, a quantization unit 140, an entropy encoding unit 150, and an inverse quantization unit. It may include a unit 160, an inverse transform unit 170, an adder 175, a filter unit 180, and a reference picture buffer 190.

An inter prediction unit 110, an intra prediction unit 120, a switch 115, a subtractor 125, a transform unit 130, a quantization unit 140, an entropy encoding unit 150, an inverse quantization unit 160, At least some of the inverse transform unit 170, the adder 175, the filter unit 180, and the reference picture buffer 190 may be program modules and may communicate with an external device or system. Program modules may be included in the encoding device 1200 in the form of an operating system, application program modules, and other program modules.

Program modules may be physically stored on various known storage devices. Also, at least some of these program modules may be stored in a remote storage device capable of communicating with the encoding device 1200 .

Program modules include routines, subroutines, programs, objects, components, and data that perform functions or operations according to an embodiment or implement abstract data types according to an embodiment. A data structure, etc. may be encompassed, but is not limited thereto.

Program modules may be composed of instructions or codes executed by at least one processor of the encoding device 1200 .

The processing unit 1210 includes an inter prediction unit 110, an intra prediction unit 120, a switch 115, a subtractor 125, a transform unit 130, a quantization unit 140, an entropy encoding unit 150, and an inverse quantization unit. Instructions or codes of the unit 160, the inverse transform unit 170, the adder 175, the filter unit 180, and the reference picture buffer 190 may be executed.

Storage may represent memory 1230 and/or storage 1240 . Memory 1230 and storage 1240 may be various forms of volatile or non-volatile storage media. For example, the memory 1230 may include at least one of a ROM 1231 and a RAM 1232 .

The storage unit may store data or information used for the operation of the encoding device 1200 . In an embodiment, data or information of the encoding device 1200 may be stored in the storage unit.

For example, the storage unit may store pictures, blocks, lists, motion information, inter prediction information, and bitstreams.

The encoding device 1200 may be implemented in a computer system including a recording medium that can be read by a computer.

The recording medium may store at least one module required for the encoding device 1200 to operate. The memory 1230 may store at least one module, and the at least one module may be configured to be executed by the processing unit 1210 .

A function related to communication of data or information of the encoding device 1200 may be performed through the communication unit 1220 .

For example, the communication unit 1220 may transmit the bitstream to the decoding apparatus 1300 to be described later.

13 is a structural diagram of a decryption device according to an embodiment.

The decryption device 1300 may correspond to the decryption device 200 described above.

The decryption apparatus 1300 includes a memory 1330, a user interface (UI) input device 1350, a UI output device 1360, and storage (1310) that communicate with each other through a bus 1390. 1340) may be included. Also, the decoding apparatus 1300 may further include a communication unit 1320 connected to the network 1399.

The processor 1310 may be a semiconductor device that executes processing instructions stored in a central processing unit (CPU), memory 1330, or storage 1340. The processing unit 1310 may be at least one hardware processor.

The processing unit 1310 may generate and process signals, data, or information input to the decoding device 1300, output from the decoding device 1300, or used inside the decoding device 1300, and signals, Inspection, comparison, and judgment related to data or information can be performed. In other words, in an embodiment, data or information generation and processing, and data or information related inspection, comparison, and judgment may be performed by the processing unit 1310 .

The processing unit 1310 includes an entropy decoding unit 210, an inverse quantization unit 220, an inverse transform unit 230, an intra prediction unit 240, an inter prediction unit 250, an adder 255, a filter unit 260 and A reference picture buffer 270 may be included.

An entropy decoding unit 210, an inverse quantization unit 220, an inverse transform unit 230, an intra prediction unit 240, an inter prediction unit 250, an adder 255, a filter unit 260, and a reference picture buffer 270 ), at least some of which may be program modules, and may communicate with an external device or system. Program modules may be included in the decryption device 1300 in the form of an operating system, application program modules, and other program modules.

Program modules may be physically stored on various known storage devices. Also, at least some of these program modules may be stored in a remote storage device capable of communicating with the decryption device 1300 .

Program modules include routines, subroutines, programs, objects, components, and data that perform functions or operations according to an embodiment or implement abstract data types according to an embodiment. A data structure, etc. may be encompassed, but is not limited thereto.

The program modules may include instructions or codes executed by at least one processor of the decoding device 1300 .

The processing unit 1310 includes an entropy decoding unit 210, an inverse quantization unit 220, an inverse transform unit 230, an intra prediction unit 240, an inter prediction unit 250, an adder 255, a filter unit 260 and Commands or codes of the reference picture buffer 270 may be executed.

Storage may represent memory 1330 and/or storage 1340 . Memory 1330 and storage 1340 may be various forms of volatile or non-volatile storage media. For example, the memory 1330 may include at least one of a ROM 1331 and a RAM 1332 .

The storage unit may store data or information used for the operation of the decoding device 1300 . In an embodiment, data or information of the decoding device 1300 may be stored in the storage unit.

For example, the storage unit may store pictures, blocks, lists, motion information, inter prediction information, and bitstreams.

The decryption device 1300 may be implemented in a computer system including a recording medium that can be read by a computer.

The recording medium may store at least one module required for the decoding apparatus 1300 to operate. The memory 1330 may store at least one module, and the at least one module may be configured to be executed by the processing unit 1310 .

A function related to communication of data or information of the decoding device 1300 may be performed through the communication unit 1320 .

For example, the communication unit 1320 may receive a bitstream from the encoding device 1200.

14 is a flowchart of a prediction method according to an embodiment.

The prediction method may be performed by the encoding device 1200 and/or the decoding device 1300.

For example, the encoding apparatus 1200 may perform the prediction method of the embodiment to compare efficiencies of a plurality of prediction schemes for a target block and/or a plurality of divided blocks, and the reconstructed data for the target block The predictive method of the embodiment may be performed to generate a block.

In one embodiment, the target block may be at least one of a CTU, a CU, a PU, a TU, a block having a specified size, and a block having a size within a predefined range.

For example, the decoding apparatus 1300 may perform the prediction method of the embodiment to generate a reconstructed block for the target block.

Hereinafter, the processing unit may correspond to the processing unit 1210 of the encoding device 1200 and/or the processing unit 1310 of the decoding device 1300.

At step 1410, the processing unit may generate a plurality of divided blocks by dividing the target block.

The processing unit may generate a plurality of divided blocks by segmenting the target block using a coding parameter associated with the target block.

In one embodiment, the processing unit may generate a plurality of divided blocks by dividing the target block based on at least one of a size of the target block and a shape of the target block.

For example, a target block may include a plurality of divided blocks. A plurality of divided blocks may be referred to as a plurality of sub blocks.

An example of step 1410 is described in detail with reference to FIG. 15 below.

In one embodiment, whether to execute step 1410, that is, whether to generate a plurality of divided blocks by dividing the target block may be determined by information related to the target block. The processing unit may determine whether to apply division of the target block based on information related to the target block.

In one embodiment, the information related to the target block includes a coding parameter for the target block, information related to a picture of a target picture including the target block, information related to a slice including the target block, and a quantization parameter of the target block (Quantization Parameter; QP), coded block flag (CBF) of the target block, size of the target block, depth of the target block, shape of the target block, entropy encoding method of the target block, division information of the reference block of the target block, target It may include at least one of a temporal layer level of a block and a block division indicator.

The reference block may include at least one of a block spatially adjacent to the target block and a block temporally adjacent to the target block.

1) In one embodiment, the processing unit may determine whether to apply division of the target block according to information related to a picture of the target picture. For example, a Picture Parameter Set (PPS) of a target picture may include information indicating whether blocks of the target picture are divided. Information indicating whether a block of a target picture is divided may be encoded and/or decoded through the PPS. Alternatively, a picture set to divide a block or a picture set not to divide a block may be identified through the PPS.

For example, when the non-square target block is included in a picture designated to divide the block, the processing unit may divide the non-square target block into square blocks.

2) In one embodiment, the processing unit may determine whether to apply segmentation of the target block based on information of the specified picture. For example, the specified picture may be a previous picture of the target picture.

For example, the processing unit may determine whether to apply the segmentation of the target block according to whether segmentation is applied to blocks of pictures preceding the target picture.

For example, if a non-square block in a picture preceding the target picture is divided into square blocks, the processing unit converts the non-square target block of the target picture to a square block. can be divided into

3) In one embodiment, the processing unit may determine whether to apply division of the target block based on slice information. A slice may include a target block. Alternatively, a slice may include a reference block.

For example, the processing unit may determine whether to apply division of the target block according to the slice type. Types of slices may include I slices, B slices, and P slices.

For example, if the non-square target block is included in the I slice, the processing unit may divide the non-square target block of the target picture into square blocks.

For example, when the non-square target block is included in a P slice or a B slice, the processing unit may divide the non-square target block into square blocks.

4) In one embodiment, the processing unit may determine whether to apply division of the target block based on information of other slices.

For example, the other slice may be a slice before or after the slice containing the target block. Another slice may be a slice including a reference block of the target block.

For example, the processing unit may determine whether to apply division of the target block according to different slice types. Other types of slices may include I slices, B slices and P slices.

For example, if the other slice is an I slice, the processing unit may divide a non-square target block of the target picture into square blocks.

For example, if the other slice is a P slice or a B slice, the processing unit may divide the non-square target block into square blocks.

5) In one embodiment, the processing unit may determine whether division of the target block is applied based on a quantization parameter of the target block.

For example, if the quantization parameter of the non-square target block is within a specified range, the processing unit may divide the non-square target block into square blocks.

6) In one embodiment, the processing unit may determine whether to apply division of the target block based on the CBF of the target block.

For example, if the value of the CBF of the non-square target block is equal to or corresponds to the specified value, the processing unit divides the non-square target block into square blocks. can do.

7) In one embodiment, the processing unit may determine whether to apply division of the target block based on the size of the target block.

For example, if the size of the non-square target block is 1) equal to the specified size, or 2) within a specified range, the processing unit converts the non-square target block into square blocks. can be divided

For example, the processing unit determines that the sum of the horizontal length and the vertical length of the non-square target block is 1) equal to a specified value, 2) greater than or equal to a specified value, 3) less than or equal to a specified value, or 4 ) within a specified range, the non-square target block may be divided into square blocks. For example, the specified value may be 16.

8) In one embodiment, the processing unit may determine whether to apply division of the target block based on the depth of the target block.

For example, if the depth of the non-square target block is 1) equal to the specified depth, or 2) within the specified range, the processing unit converts the non-square target block into square blocks. can be divided

9) In one embodiment, the processing unit may determine whether to apply division of the target block based on the shape of the target block.

For example, if the ratio of the horizontal length and the vertical length of the non-square target block is 1) equal to a specified value, or 2) within a specified range, the processing unit converts the non-square target block into a square. It can be divided into blocks of the form of

10) In one embodiment, the processing unit may determine whether to apply division of the target block based on the block division indicator.

The block division indicator may be an indicator indicating whether a target block is to be divided. Also, the block division indicator may indicate a type of block division.

The type of segmentation may include the direction of segmentation. The direction of division may be vertical or horizontal.

The type of partitioning may include the number of partitioned blocks generated by partitioning.

In embodiments, the indicator may be information explicitly signaled from the encoding device 1200 to the decoding device 1300 through a bitstream. In one embodiment, the indicator may include a block division indicator.

When a block division indicator is used, the decoding apparatus 1300 may directly determine whether or not to divide the target block and the type of division based on the block division indicator provided from the encoding apparatus 1200.

A block partitioning indicator may be optional. If the block division indicator is not used, the processing unit may determine whether or not to divide the target block and the type of division according to conditions for using information related to the target block. Accordingly, whether to divide the target block can be determined without signaling additional information.

For example, the processing unit may divide a non-square shaped target block into square shaped blocks if the block splitting indicator indicates that the target block is to be divided.

The block division indicator may be encoded and/or decoded for at least one unit of SPS, PPS, slice header, tile header, CTU, CU, PU, and TU. In other words, the unit provided with the block division indicator may be at least one of SPS, PPS, slice header, tile header, CTU, CU, PU, and TU. A block division indicator provided for a specified unit may be commonly applied to one or more target blocks included in the specified unit.

11) In one embodiment, the processing unit may determine whether to apply the division of the target block based on the division information of the reference block.

A reference block can be a spatial neighboring block and/or a temporal neighboring block.

For example, the partitioning information may be at least one of quad-tree partitioning information, binary-tree partitioning information, and quad-tree plus binary-tree information.

For example, the processing unit may divide a target block of a non-square shape into blocks of a square shape if the information of the division of the reference block indicates that the target block is to be divided.

12) In one embodiment, the processing unit may determine whether to apply division of the target block based on a temporal layer level of the target block.

For example, if the temporal layer level of the non-square target block is 1) equal to a specified value, or 2) within a specified range, the processing unit converts the non-square target block to a square block. can be divided into

13) Also, in one embodiment, the information related to the target block may further include information used for encoding and/or decoding of the target block described above.

In the above-described embodiments 1) to 13), the specified value, the specified range, and/or the specified unit may be determined by the encoding device 1200 or the decoding device 1300. When the specified value, the specified range, and the specified unit are determined by the encoding device 1200, the determined specified value, the specified range, and/or the specified unit are decoded from the encoding device 1200 through a bitstream. It may be signaled to the device 1300.

Alternatively, the specified value, specified range and/or specified unit may be derived by other coding parameters. When coding parameters are shared between the encoding device 1200 and the decoding device 1300 through a bitstream or can be identically derived from the encoding device 1200 and the decoding device 1300 by a predefined derivation method, a specific The specified value, the specified range, and/or the specified unit may not be signaled from the encoding device 1200 to the decoding device 1300.

In the above-described embodiments 1) to 13), determining whether to divide a target block based on the criterion of the shape of the target block is only an example. In the above-described embodiments 1) to 13), whether or not the target block is divided may be combined with other criteria described in the embodiments, such as the size of the target block.

In step 1420, the processing unit may derive a prediction mode for at least some of the plurality of divided blocks.

In one embodiment, prediction may be intra prediction or inter prediction.

An example of step 1420 is described in detail with reference to FIG. 21 below.

At step 1430, the processing unit may perform predictions for a plurality of partitioned blocks based on the derived prediction mode.

In one embodiment, the processing unit may perform prediction on at least some of the plurality of partitioned blocks using the derived prediction mode. The processing unit may perform prediction on the remaining blocks among the plurality of divided blocks by using a prediction mode generated based on the derived prediction mode.

Prediction for the divided blocks will be described with reference to FIGS. 22, 23, 24, 25, 26, 27 and 28 below.

15 is a flowchart of a block division method according to an embodiment.

The block division method of the embodiment may correspond to step 1410 described above. Step 1410 may include at least one of steps 1510 and 1520 .

In step 1410, the processing unit may generate a plurality of divided blocks by dividing the target block based on one or more of a size of the target block and a shape of the target block.

The size of the target block may mean a horizontal length of the target block and/or a vertical length of the target block.

The shape of the target block may indicate whether the target block is a square. The shape of the target block may indicate whether the target block is square or non-square. The shape of the target block may be a ratio of a horizontal length and a vertical length of the target block.

The processing unit may generate a plurality of divided blocks by dividing the target block using at least one of a method of selecting a prediction mode in step 1510 and a method of selecting a prediction mode in step 1520 .

In step 1510, the processing unit may generate a plurality of divided blocks by dividing the target block based on the horizontal length or the vertical length of the target block.

In one embodiment, the processing unit may divide the target block when the horizontal length and the vertical length of the target block are different from each other.

In one embodiment, the processing unit may divide a greater length of the horizontal length and the vertical length of the target block at least once.

In one embodiment, the processor may divide the target block so that the horizontal and vertical lengths of the divided blocks are the same. Alternatively, the horizontal and vertical lengths of the divided blocks generated by division may be equal to or greater than the smaller of the horizontal and vertical lengths of the target block.

An example of the target block and division of the target block based on the length are exemplified with reference to FIGS. 16, 17, 18, 19, and 20 below.

In one embodiment, the processing unit may divide the target block when the size of the target block is smaller than the specified size and the horizontal length and vertical length of the target block are different from each other.

In one embodiment, the processing unit may divide the target block when the sum of the horizontal length and the vertical length of the target block is smaller than a specified value and the horizontal length and vertical length of the target block are different from each other.

In one embodiment, the processing unit may divide the target block when the size of the target block is within a specified range and the horizontal length and vertical length of the target block are different from each other.

In step 1520, the processing unit may generate a plurality of divided blocks by dividing the target block based on the shape of the target block.

When the shape of the target block is a square, the processing unit may not divide the target block.

If the shape of the target block is non-square, the processing unit may divide the target block into a square shape. The division in the form of a square is illustrated with reference to FIGS. 16, 17, 18 and 20 below.

As described above in steps 1510 and 1520, the processing unit only uses the size and shape of the target block in determining whether or not to split the target block, and uses information directly indicating whether the target block is divided or not. may not use it. Accordingly, information indicating whether a block is divided may not be signaled from the encoding apparatus 1200 to the decoding apparatus 1300, and whether a block is divided may be derived based on the size and/or shape of the target block.

16 illustrates a target block having a size of 8x4 according to an example.

In FIG. 17, the division of the target block is explained.

17 illustrates divided blocks having a size of 4x4 according to an example.

Each size of the first divided block and the second divided block may be 4x4.

As shown in FIG. 17 , when the horizontal length of the target block is greater than the vertical length, two divided blocks may be derived by vertically dividing the horizontal length of the target block shown in FIG. 16 .

18 illustrates a target block having a size of 4x16 according to an example.

19 and 20, the division of the target block is explained.

19 shows divided blocks having a size of 8x4 according to an example.

Each size of the first divided block and the second divided block may be 8x4.

20 shows divided blocks having a size of 4x4 according to an example.

Each of the first divided block, the second divided block, the third divided block, and the fourth divided block may have a size of 4x4.

As shown in FIGS. 19 and 20, when the vertical length of the target block is greater than the horizontal length, by horizontally dividing the vertical length of the target block shown in FIG. 18, two divided blocks or 4 The number of divided blocks may be derived.

21 is a flowchart of a method of deriving a prediction mode for a divided block according to an example.

The method for deriving a prediction mode in an embodiment may correspond to step 1420 described above. Step 1420 may include at least one of steps 2110, 2120 and 2130.

For a plurality of divided blocks generated by division of the target block, 1) prediction modes may be derived for each of the plurality of divided blocks, and 2) a specified divided block among the plurality of divided blocks A prediction mode may be derived for , and 3) a prediction mode common to all of a plurality of divided blocks may be derived.

Depending on the subject of the derived prediction mode, at least one of steps 2110, 2120 and 2130 may be performed.

At step 2110, the processing unit may derive prediction modes for each of the plurality of partitioned blocks.

The processing unit may derive a prediction mode for each of a plurality of divided blocks using the method of deriving a prediction mode described above in the embodiments.

In step 2120, the processing unit may derive a prediction mode for a specified partitioned block among a plurality of partitioned blocks.

The specified divided block may be a block at a specified position among a plurality of divided blocks.

For example, the specified divided block is the uppermost block, the lowermost block, the leftmost block, the rightmost block, the nth block from the top, the nth block from the bottom, and the leftmost block among the plurality of divided blocks. It may be one or more of the n-th block from and the n-th block from the right. n may be an integer greater than or equal to 1 and less than or equal to the number of divided blocks.

In one embodiment, the processing unit may derive a prediction mode for a specified partitioned block among a plurality of partitioned blocks by using the prediction mode derivation method described in the embodiments.

In one embodiment, a derived prediction mode may be used for blocks other than a specified divided block among a plurality of divided blocks. The processing unit may use the derived prediction mode for blocks other than the specified divided block among the plurality of divided blocks.

In one embodiment, a combination of a derived prediction mode and another prediction mode may be used for blocks other than a specified divided block among a plurality of divided blocks. The processing unit may use a prediction mode determined by a combination of a prediction mode derived for blocks other than a specified divided block among a plurality of divided blocks and other prediction modes.

For example, another prediction mode may be determined using a coding parameter associated with each of the remaining blocks. The processing unit may determine an additional prediction mode using the coding parameters associated with the remaining block, and the prediction mode for the remaining block may be determined using a combination of the additional prediction mode and the prediction mode derived for the specified block described above. can decide

For example, a combination of prediction modes may be a prediction mode indicating a direction between directions of prediction modes. A combination of prediction modes may be a prediction mode selected by a specified priority among prediction modes. A prediction mode determined using a combination of prediction modes may be different from each of the prediction modes used for the combination.

At step 2130, the processing unit may derive a prediction mode common to all of the plurality of partitioned blocks. In other words, one prediction mode common to a plurality of divided blocks can be derived.

For example, the processing unit may derive a common prediction mode for all of the divided blocks by using a coding parameter common to all of the plurality of divided blocks.

Derivation of the prediction mode using the Most Probable Mode (MPM)

In the above-mentioned derivation of the prediction mode of the divided block, the processing unit may use MPM.

To use MPM, the processing unit may construct a list of MPMs.

An MPM list may include one or more MPM candidate modes. One or more MPM candidate modes may be N. N may be a positive integer.

In one embodiment, the processing unit may determine the value of N according to the size and/or shape of the target block. Alternatively, the processing unit may determine the value of N according to the size, shape and/or number of divided blocks.

Each MPM candidate mode of one or more MPM candidate modes may be one intra prediction mode among predefined intra prediction modes.

The processing unit may construct one or more MPM candidate modes of the MPM list based on one or more prediction modes of one or more reference blocks of the target block. The reference block may be a block at a predefined position or a block adjacent to the target block. For example, one or more reference blocks may be a block adjacent to the top of the target block and a block adjacent to the left of the target block.

One or more MPM candidate modes may be one or more prediction modes determined based on prediction modes of reference blocks. The processing unit may determine one or more prediction modes specified with reference to prediction modes of one or more reference blocks as one or more MPM candidate modes. In other words, one or more MPM candidate modes may be prediction modes with a high probability of being the prediction modes of the target block. This probability may be calculated by experiments or the like. For example, it is known that the prediction mode of the reference block is highly likely to be used as the prediction mode of the target mode due to the regional association between the reference block and the target block. Accordingly, the prediction mode of the reference block may be included in one or more MPM candidate modes.

In one embodiment, there may be one or more MPM lists, and may be plural. For example, there may be M MPM lists. M may be a positive integer. The processing unit may construct each MPM list of the plurality of MPM lists using different methods.

For example, the processing unit may configure a first MPM list, a second MPM list, and a third MPM list.

MPM candidate modes in one or more MPM lists may be different. Alternatively, MPM candidate modes of one or more MPM lists may not overlap each other. For example, when a specified intra prediction mode is included in one MPM list, a plurality of MPM lists may be configured such that the specified intra prediction mode is not included in another MPM list.

An MPM list indicator may be used to specify an MPM list including a prediction mode used for encoding and/or decoding a target block among one or more MPM lists. That is, an MPM list indicated by an MPM list indicator among one or more MPM lists may be specified, and the processing unit may use one MPM candidate among one or more MPM candidate modes of the specified MPM list for prediction of a target block.

The MPM list indicator may be signaled from the encoding device 1200 to the decoding device 1300 through a bitstream.

When the MPM list indicator is used, in the decoding device 1300, the MPM candidate mode of which MPM list among one or more lists is to be used for prediction of the target block is directly indicated by the MPM list indicator provided from the encoding device 1200. can be determined

In one embodiment, the MPM use indicator may indicate whether to determine a prediction mode using an MPM list.

The MPM use indicator may indicate whether a prediction mode of a target block exists among one or more MPM candidate modes in the configured MPM list.

When the MPM use indicator indicates that the prediction mode of the target block exists among one or more MPM candidate modes, the processing unit may use the index indicator to determine the prediction mode of the target block among one or more MPM candidate modes.

The index indicator may indicate an MPM candidate mode to be used for prediction of a target block among one or more MPM candidate modes of the MPM list. The processing unit may determine an MPM candidate mode indicated by an index indicator among one or more MPM candidate modes of the MPM list as a prediction mode of the target block. An index indicator may also be named an MPM index.

When an MPM list is indicated by an MPM list indicator among one or more MPM lists, which MPM candidate mode among one or more MPM candidate modes of the MPM list indicated by the MPM list is used for prediction of the target block An index indicator may be used to indicate the . In other words, the prediction mode of the target block can be specified by the MPM list indicator and the index indicator.

When the MPM use indicator indicates that the prediction mode of the target block does not exist among one or more MPM candidate modes in the MPM list, the processing unit may determine the prediction mode of the target block using a prediction mode indicator indicating the prediction mode of the target block. there is. A prediction mode indicator may indicate a prediction mode of a target block.

The prediction mode indicator may indicate one of prediction modes not included in the MPM list (or one or more MPM lists). In other words, the MPM list or one or more prediction modes not included in the one or more MPM lists may be configured as a prediction mode list in a predefined order, and the prediction mode indicator is one prediction of one or more prediction modes of the prediction mode list. mode can be indicated.

One or more prediction modes of the prediction mode list may be ordered in ascending or descending order. Here, a criterion for sorting may be the number of prediction modes.

When there are a plurality of MPM lists, a separate MPM use indicator may be used for each of the plurality of MPM lists. Alternatively, when there are a plurality of MPM lists, MPM use indicators may exist for some of the plurality of MPM lists.

For example, the n-th MPM use indicator for the n-th MPM list may indicate whether the prediction mode of the target block exists in the n-th MPM list.

First, the processing unit may determine whether a prediction mode of the target block exists in the first MPM list using the first MPM use indicator. When the prediction mode of the target block exists in the first MPM list, the processing unit may derive an MPM candidate mode indicated by an index indicator in the first MPM list as the prediction mode of the target block. When the prediction mode of the target block does not exist in the first MPM list, the processing unit may determine whether the prediction mode of the target block exists in the second MPM list by using the second MPM use indicator.

The processing unit may determine whether the prediction mode of the target block exists in the n-th MPM list by using the n-th MPM use indicator. If the prediction mode of the target block exists in the n-th MPM list, the processing unit may determine an MPM candidate mode indicating the prediction mode of the target block in the n-th MPM list by using the index indicator. If the prediction mode of the target block does not exist in the first MPM list, the processing unit may determine whether the prediction mode of the target block exists in the n + 1 MPM list using the following n + 1 th MPM use indicator. there is.

When one MPM use indicator indicates that the prediction mode of the target block exists in the MPM list, MPM use indicators following the other MPM use indicators may not be signaled.

The MPM use indicator, index indicator, and/or prediction mode indicator may be signaled from the encoding device 1200 to the decoding device 1300 through a bitstream.

When the MPM use indicator, index indicator, and/or prediction mode indicator are used, the decoding apparatus 1300 selects 1) MPM candidate modes of one or more MPM lists and 2) one or more prediction modes not included in one or more lists. , which MPM candidate mode or prediction mode will be used for prediction of the target block can be directly determined by the MPM use indicator, index indicator, and/or prediction mode indicator provided from the encoding apparatus 1200.

The MPM list can be configured for a specified unit.

In one embodiment, a specified unit may be a block or target block having a specified size.

When the specified unit is divided, the processing unit may use the constructed MPM list for prediction of a plurality of divided blocks generated by the division.

In one embodiment, when the size of the target block is equal to or corresponds to the specified size, the processing unit may construct an MPM list for the target block. When the target block is divided into a plurality of divided blocks, the processing unit may derive a prediction mode of each divided block of the plurality of divided blocks by using the MPM list configured for the target block.

For example, when the size of the target block is 8x8 and the divided blocks are four 4x4 blocks, an MPM list for the 8x8 block may be configured, and the MPM list configured for each of the four 4x4 blocks An MPM list may be used.

In one embodiment, in constructing the MPM list, the processing unit may configure the MPM list for each of the divided blocks within the block of the specific size based on the block of the specific size. In other words, an MPM list generated for a block of a specified size may be commonly used for divided blocks.

For example, when the size of the target block is the specified size, the MPM list for each divided block in the target block is obtained by using prediction modes of one or more reference blocks of the target block (not the divided block). can be configured.

For example, when the size of the target block is 8x8 and the divided blocks are four 4x4 blocks, the processing unit generates MPM lists for each of the four divided blocks based on one or more reference blocks of the target block. can be configured. In this case, since the prediction mode of the reference block of the target block has already been obtained, the processing unit can construct MPM lists for the four divided blocks in parallel.

22 illustrates prediction of a divided block according to an example.

In FIG. 22 , the first block may be a specific block among divided blocks. For example, the first block may be a block for which prediction is first performed among divided blocks.

The processing unit may derive a prediction mode for the first block in predicting the first block.

As shown in FIG. 22 , the processing unit may use reference samples adjacent to the first block in prediction of the first block. Alternatively, the reference samples may be pixels around the first block. Reference samples may be pixels of a reconstructed block adjacent to the first block.

23 illustrates prediction of a divided block using a reconstructed block of the divided block according to an example.

In FIG. 23 , the second block may be a specific block among divided blocks. For example, among the divided blocks, the second block is 2) the block in which prediction is performed second, 3) the block in which prediction is performed last, and 3) the prediction performed next to the prediction of the first block. Block 4) may be a block in which prediction is performed after prediction of the first block, or 5) a block in which prediction is performed after prediction of at least one divided block.

As described above, the processing unit may use the derived prediction mode for the first block in predicting the second block.

As shown in FIG. 22 , the processing unit may use reference samples adjacent to the second block in predicting the second block.

Reference samples may be pixels of a reconstructed block adjacent to the second block. The reference samples may include reconstructed pixels of the reconstructed block of the first block.

Alternatively, the reference samples may include reconstructed pixels of a reconstructed block of another partitioned block predicted before prediction of the second block. In other words, in prediction of the second block, another divided block predicted before prediction of the second block among the plurality of divided blocks may be used.

24 illustrates prediction of a divided block using a reference pixel outside the divided block according to an example.

The processing unit may use pixels outside of the plurality of divided blocks as reference samples in prediction of the divided blocks. In other words, in prediction of the divided blocks, the processing unit may exclude pixels inside the plurality of divided blocks from the reference sample. A pixel excluded from the reference sample is 1) replaced by the nearest pixel in the same direction as the excluded pixel, or 2) replaced by a pixel adjacent to the target block in the same direction as the excluded pixel. It can be.

In one embodiment, in predictions of a plurality of divided blocks, reference samples used for the predictions may be reconstructed pixels adjacent to the target block (not each divided block).

For example, as shown in FIG. 24 , in predicting the second block, the processing unit may exclude pixels in the reconstructed block of the first block from the reference sample, and instead reconstruct the reconstructed block adjacent to the reference block. Pixels can be used as reference samples.

For example, the processing unit may use reconstructed pixels adjacent to the target block as reference samples for prediction of each divided block among a plurality of divided blocks generated by dividing the target block. Through the determination of the reference sample, values of all reference samples used for predictions of the plurality of divided blocks may be determined prior to predictions of the plurality of divided blocks. Accordingly, the processing unit may determine values of all reference samples used for predictions of the plurality of divided blocks prior to predictions of the plurality of divided blocks, and may perform predictions of the plurality of divided blocks in parallel. .

25 illustrates prediction of four divided blocks according to an example.

As shown in FIG. 25 , four divided blocks of a first block, a second block, a third block, and a fourth block may be generated by dividing the target block.

As described above, the processing unit may derive a prediction mode for a specified partitioned block among a plurality of partitioned blocks.

In FIG. 25 , a prediction mode may be exemplarily induced for a fourth block, which is the lowest block. The derived prediction mode may be used for the remaining blocks, i.e., the first block, the second block, and the third block.

The processing unit may preferentially perform prediction on a specified divided block from which a prediction mode is derived from among a plurality of divided blocks. Next, the processing unit may perform prediction using the derived prediction mode for blocks other than the specified block among the plurality of blocks.

The processing unit may use reconstructed pixels around the specified divided block and/or the target block as reference samples when performing prediction on the specified divided block from which the prediction mode is derived.

According to FIG. 25 , a reconstructed pixel adjacent to an upper end of the fourth block may not exist at the time of prediction of the fourth block. Accordingly, the processing unit may use reconstructed pixels adjacent to an upper end of the target block as reference pixels in prediction of the fourth block.

The processing unit may perform predictions of a plurality of divided blocks according to a predefined order. The predefined order may differ from the order for normal blocks not created by partitioning. For example, the predefined order may be 1) from the bottommost block to the topmost block, or 2) from the rightmost block to the leftmost block. Alternatively, the predefined order may be: 3) the lowest block is selected first, and then sequentially selected from the top block to the second block from the bottom, or 4) the rightmost block is the most selected. After being selected first, the next block may be sequentially selected from the leftmost block to the second rightmost block.

Alternatively, the predefined order may be arbitrarily determined by the encoding device 1200 and/or the decoding device 1300. When the predefined order is determined by the encoding device 1200, the determined predefined order may be signaled from the encoding device 1200 to the decoding device 1300.

The prediction order indicator may indicate the order of predictions for a plurality of divided blocks. The encoding device 1200 may determine a value of a prediction order indicator. The prediction sequence indicator may be signaled from the encoding device 1200 to the decoding device 1300 through a bitstream.

Alternatively, the predefined order may be derived according to the same predefined method in each of the encoding device 1200 and/or the decoding device 1300 . The processing unit may derive a predefined order using coding parameters related to the target block.

26 illustrates prediction of a first block after prediction of a fourth block is performed according to an example.

As described above, in performing predictions of a plurality of partitioned blocks, a predefined order may be used.

In the predefined order illustrated in FIG. 26, prediction of the lowest block among a plurality of divided blocks is performed first, and then blocks are sequentially executed from top to bottom from the top block to the second block from the bottom to the next. Prediction for may be performed. In the order of the embodiments, "bottom" may be replaced with "rightmost" and "topmost" may be replaced with "leftmost" respectively.

Since predictions of a plurality of divided blocks are performed according to a predefined order, as shown in FIG. 26, additional reference samples may be available compared to performing predictions of a plurality of divided blocks according to an existing order. can Therefore, intra prediction in a different direction using additionally available reference samples compared to general intra prediction may be used.

In performing prediction on each divided block of a plurality of divided blocks, the processing unit may use pixels of a reconstructed block of a previously predicted divided block as reference samples for prediction on each divided block. there is.

For example, as shown in FIG. 26 , in prediction of the first block, the processing unit may use pixels of a reconstructed block of a previously predicted fourth block as reference samples.

Depending on the use of this predefined order and the use of pixels in the reconstructed block of the previously predicted partitioned block, reference samples in more directions than performing prediction on a block partitioned in the normal order only can be provided. For example, as shown in FIG. 26 , reference samples positioned below the first block may be provided.

In one embodiment, the processing unit may perform intra prediction using reference samples adjacent to the bottom of the divided block in prediction of the divided block, and intra prediction using reference samples adjacent to the right of the divided block. can make predictions.

For example, reference samples adjacent to the lower end of the divided block may be copied into the prediction block in upward, upward-left and/or upward-order directions. Reference samples adjacent to the right side of the divided block may be copied into the prediction block in a leftward, upwards and/or downwards direction.

27 illustrates prediction of a second block according to an example.

The prediction of the second block may be performed after the prediction of the fourth block and the prediction of the first block. Therefore, as described above, pixels of the reconstructed block of the fourth block and pixels of the reconstructed block of the first block may be included as reference samples used for prediction of the second block.

In other words, the processing unit may use pixels of reconstructed blocks of other divided blocks as reference samples in performing prediction on a specified divided block among a plurality of divided blocks. Here, other partitioned blocks may be blocks on which prediction of a particular partitioned block among a plurality of partitioned blocks has previously been performed.

Alternatively, when the prediction of the third block is performed earlier than the prediction of the second block, the reference samples shown in FIG. 27 may be used for prediction of the third block.

28 shows prediction of a third block according to an example.

The prediction of the third block may be performed last after the prediction of the fourth block, the prediction of the first block, and the prediction of the second block.

28 may indicate reference samples available for prediction of a third block.

In one embodiment, in a divided block, a reference sample type to be used for prediction of the divided block may be selected from among a plurality of reference sample types.

For example, in the prediction of the third block, the processor uses the reference samples shown in FIG. 25, the reference samples shown in FIG. 26, the reference samples shown in FIG. 27, and the reference samples shown in FIG. 28. one of them can be used.

The processing unit may use reference samples according to one reference sample type among a plurality of reference sample types in performing prediction on a specified partitioned block.

The plurality of reference sample types may include a first reference sample type, a second reference sample type, and a third reference sample type.

Reference samples of the first reference sample type may be reconstructed pixels adjacent to the target block. In other words, the reference samples of the first reference sample type may be the reference samples shown in FIG. 25 .

Reference samples of the second reference sample type may be reference samples of the first reference sample type and pixels of a reconstructed block of a previously predicted partitioned block. In other words, the reference samples of the second reference sample type may be the reference samples shown in FIG. 26 or FIG. 27 .

In one embodiment, pixels of a reconstructed block of a previously segmented block on which prediction has been performed may only be used for directions not covered by reconstructed pixels adjacent to the target block. In other words, reconstructed pixels adjacent to the target block may be used with priority over pixels of the reconstructed block of the divided block. (eg, reference samples shown in FIG. 26)

Alternatively, in an embodiment, pixels of a reconstructed block of a divided block on which prediction has been previously performed may replace at least some of reconstructed pixels adjacent to the target block. (eg, reference samples shown in FIG. 27)

In other words, pixels of a reconstructed block of a divided block may be used more preferentially than reconstructed pixels adjacent to the target block.

That is, since the pixels of the reconstructed block of the previously predicted partitioned block are closer to the specified partitioned block than the reconstructed samples adjacent to the target block, the reconstruction of the previously predicted partitioned block Pixels of the constructed block may be used for prediction for a specified partitioned block (instead of reconstructed pixels adjacent to the target block), and reconstructed pixels adjacent to the target block may be used for the partitioned block on which prediction was previously performed. can be used only for directions not covered by pixels of the reconstructed block of .

Reference samples of the third reference sample type may be reconstructed pixels adjacent to the specified partitioned block. In other words, the reference samples of the third reference sample type may be the reference samples shown in FIG. 28 .

In one embodiment, the processing unit may determine reference samples to be used in prediction of the partitioned block using information related to the target block or the partitioned block.

In one embodiment, the processing unit may determine reference samples to be used in prediction for the partitioned block based on the reference sample indicator.

The reference sample indicator may be an indicator indicating reference samples to be used in prediction of a block. The reference sample indicator may indicate a reference sample type to be used in prediction of a block among a plurality of reference sample types.

The processing unit may determine the value of the reference sample indicator.

The reference sample indicator may be signaled from the encoding device 1200 to the decoding device 1300 through a bitstream. Alternatively, coding parameters associated with the reference block or partitioned block may be used to at least partially determine the reference sample indicator.

When a reference sample indicator is used, in the decoding apparatus 1300, reference samples to be used for prediction of a divided block may be directly determined by the reference sample indicator provided from the encoding apparatus 1200.

Filtering on reference samples

Prior to the aforementioned prediction, the processing unit may perform filtering on the reference samples, and may determine whether to perform filtering on the reference samples.

In one embodiment, the processing unit may determine whether to perform filtering on the reference samples based on the size and/or shape of the target block.

In one embodiment, the processing unit may determine whether to perform filtering on the reference samples based on the size and/or shape of the divided blocks.

In an embodiment, the processing unit may determine whether to perform filtering on the reference samples according to whether a reconstructed block adjacent to the target block is used as a reference block of the divided block.

In one embodiment, the processing unit may determine whether to perform filtering on the reference samples according to whether predictions of the divided blocks are performed in parallel.

Alternatively, in one embodiment, the processing unit may determine whether to perform filtering on the reference samples according to whether the specified function, operation, and processing described in the embodiment is performed.

Alternatively, in one embodiment, the processing unit may determine whether to perform filtering on the reference samples based on coding parameters related to the target block or coding parameters related to the divided blocks.

29 is a flowchart of a prediction method according to an embodiment.

In the embodiment described above with reference to FIG. 14, a plurality of divided blocks are generated by dividing a target block in step 1410, and at least some of the prediction modes of the plurality of divided blocks are generated in step 1420. The predictive mode has been described as being induced.

In this embodiment, a plurality of divided blocks may be generated by first inducing a prediction mode and then dividing a target block.

At step 2910, the processing unit may derive a prediction mode.

For example, the derived prediction mode may be a prediction mode for the target block. The processing unit may derive a prediction mode according to the method of inducing the prediction mode for the target block described above.

For example, the derived prediction mode may be a prediction mode used for predictions of a plurality of divided blocks generated by dividing the target block when division of the target block is performed. In other words, the derived prediction mode may be a prediction mode used when the target block is divided.

In one embodiment, the derived prediction modes may be multiple.

For example, a plurality of derived prediction modes may be respectively used for predictions of a plurality of partitioned blocks generated by partitioning of the target block.

The description related to the derivation of the prediction mode of the divided block in the above-described embodiment can also be applied to the derivation of the prediction mode of the present embodiment. For example, MPM can be used in the derivation of prediction modes. Redundant descriptions are omitted.

In step 2920, the processing unit may generate a plurality of divided blocks by dividing the target block.

The description related to the division of the target block described above with reference to step 1410 may also be applied to step 2920 . Redundant descriptions are omitted.

In step 2930, the processing unit may perform prediction on at least some of the plurality of partitioned blocks using the derived prediction mode.

The description related to prediction of at least some blocks among the plurality of divided blocks described above with reference to step 1430 may also be applied to step 2930 . However, in the description with reference to steps 1420 and 1430, the prediction mode is induced for a specified partitioned block among a plurality of divided blocks, and the specified partitioning is performed for the remaining blocks except for the specified partitioned block. It has been described that the derived prediction mode or the prediction mode determined based on the derived prediction mode is used for the derived block. This description is to be understood that a prediction mode is derived in step 2910, and the prediction mode derived in step 2910 or the prediction mode determined based on the derived prediction mode is used for a plurality of partitioned blocks. It can be. Redundant descriptions are omitted.

30 illustrates derivation of a prediction mode for a target block according to an example.

As described above in the embodiment of FIG. 29 , a prediction mode for a target block may be derived in step 2910 . When the prediction mode for the target block is derived, predictions for the first block and the second block may be performed using the derived prediction mode, similarly to that described above with reference to FIGS. 22 , 23 , and 24 .

Alternatively, in step 2910, a plurality of prediction modes may be derived for the target block. A plurality of derived prediction modes may be used for predictions of partitioned blocks, respectively.

The processing unit may determine which prediction mode among a plurality of derived prediction modes to use for prediction of which divided block according to a method using a coding parameter related to a target block.

31 is a flowchart of a method of predicting a target block and generating a bitstream according to an embodiment.

The prediction method of the target block and the bitstream generation method of the embodiment may be performed by the encoding device 1200 . An embodiment may be a part of a method of encoding a target block or a method of video encoding.

In step 3110, the processing unit 1210 may perform division of a block and derivation of a prediction mode.

Step 3110 may correspond to steps 1410 and 1420 described above with reference to FIG. 14 . Step 3110 may correspond to steps 2910 and 2920 described above with reference to FIG. 29 .

At step 3120, processing unit 1210 may perform a prediction using a derived prediction mode.

Step 3120 may correspond to step 1430 described above with reference to FIG. 14 . Step 3120 may correspond to step 2930 described above with reference to FIG. 29 .

At step 3130, processing unit 1210 may generate prediction information. Predictive information may be generated at least in part at step 3110 or step 3120 .

Prediction information may be information used for the above-described division of a block and derivation of a prediction mode. For example, prediction information may include the aforementioned indicators.

At step 3140, the processing unit 1210 may generate a bitstream.

A bitstream may include information about an encoded target block. For example, the information on the encoded target block may include transform and quantized coefficients of the target block and/or divided blocks, and may include coding parameters of the target block and/or divided blocks. A bitstream may include prediction information.

The processing unit 1210 may perform entropy encoding on the prediction information and generate a bitstream including the entropy-encoded prediction information.

The processing unit 1210 may store the generated bitstream in the storage 1240 . Alternatively, the communication unit 1220 may transmit the bitstream to the decoding apparatus 1300.

32 is a flowchart of a method of predicting a target block using a bitstream according to an embodiment.

A method of predicting a target block using the bitstream of the embodiment may be performed by the decoding apparatus 1300. The embodiment may be part of a decoding method of a target block or a video decoding method.

In step 3210, the communication unit 1320 may obtain a bitstream. The communication unit 1320 may receive a bitstream from the encoding device 1200 .

A bitstream may include information about an encoded target block. For example, the information on the encoded target block may include transform and quantized coefficients of the target block and/or divided blocks, and may include coding parameters of the target block and/or divided blocks. A bitstream may include prediction information.

The processing unit 1310 may store the obtained bitstream in the storage 1240 .

In step 3220, the processing unit 1310 may obtain prediction information from the bitstream.

The processing unit 1310 may obtain prediction information by performing entropy decoding on the entropy-encoded prediction information of the bitstream.

In step 3230, the processing unit 1210 may perform division of a block and derivation of a prediction mode using the prediction information.

Step 3230 may correspond to steps 1410 and 1420 described above with reference to FIG. 14 . Step 3230 may correspond to steps 2910 and 2920 described above with reference to FIG. 29 .

At step 3240, processing unit 1210 may perform a prediction using a derived prediction mode.

Step 3240 may correspond to step 1430 described above with reference to FIG. 14 . Step 3240 may correspond to step 2930 described above with reference to FIG. 29 .

Splitting blocks using splitting directives

In the above-described embodiment, it has been described that the target block is divided based on the size and/or shape of the target block.

For segmentation of blocks, a segmentation indicator may be used. The block division indicator may indicate whether to generate two or more divided blocks by dividing the block in encoding and decoding of the block and use each divided block of the generated divided blocks as a unit of encoding and decoding. .

The descriptions related to block partitioning and block prediction described in the above-described embodiments may also be applied to the following embodiments.

In one embodiment, the block splitting indicator may be a binary tree splitting indicator indicating whether to split the block in the form of a binary tree. For example, the name of the binary tree split indicator may be “binarytree_flag” or “BTsplitFlag”.

Alternatively, the block splitting indicator may be a quad tree splitting indicator indicating whether to split the block in the form of a quad tree.

In an embodiment, a first predefined value among values of the splitting indicator may indicate not splitting a block, and a second predefined value may indicate splitting a block.

If the splitting indicator of the block has a first predefined value, the processing unit may not split the block.

In one embodiment, if a splitting indicator of a block is present and the splitting indicator has a first predefined value, the block may not be split even if the block has a shape and form to which splitting is applied.

In one embodiment, when a division indicator of a block has a second predefined value, the processing unit may divide the block to generate divided blocks, and perform encoding and/or decoding on the divided blocks. there is. In addition, when the division indicator of the block has a second predefined value, the processing unit may divide the block to generate divided blocks, and the divided block may be re-divided according to the shape and/or shape of the divided block. It could be.

In one embodiment, the division indicator of the target block may indicate whether to divide the target block with respect to the target block. In addition, the division indicator of the upper block of the target block may indicate whether to divide the upper block. When the division indicator of the upper block indicates that the upper block is divided into a plurality of blocks, the processor may divide the upper block into a plurality of blocks including the target block. That is, the target block described above in the embodiments may also be regarded as a block generated by division by a division indicator or the like.

33 illustrates division of an upper block according to an example.

For example, if the value of the division indicator of the upper block is the second predefined value and the value of the division indicator of the target block is the first predefined value, the upper block is divided into a plurality of blocks including the target block. and a plurality of blocks including the target block may be an object or unit of a specified process of encoding and/or decoding, respectively.

34 illustrates division of a target block according to an example.

For example, when the value of the division indicator of the upper block is a second predefined value, and the target block generated by division of the upper block has a size and/or shape to which division is applied, the target block is again divided into a plurality of Can be divided into blocks. Each divided block of a plurality of divided blocks may be an object or unit of a specified process of encoding and/or decoding.

Block division for block conversion, etc.

In the above-described embodiment, it has been described that divided blocks are units of prediction. The divided blocks of the embodiment may be units of other processing in encoding and/or decoding other than prediction.

In the following embodiments, an embodiment in which a target block or a divided block is used as a unit of processing for prediction, transformation, quantization, inverse transformation, and inverse quantization in encoding and/or decoding of a block will be described.

35 is a signal flowchart illustrating a method of encoding and decoding an image according to an exemplary embodiment.

In step 3510, the processing unit 1210 of the encoding device 1200 may perform prediction related to the target block.

In step 3520, the processing unit 1210 of the encoding apparatus 1200 may perform transformation related to the target block based on the prediction.

In step 3530, the processing unit 1210 of the encoding device 1200 may generate a bitstream including a result of the conversion.

In step 3540, the communication unit 1220 of the encoding apparatus 1200 may transmit the bitstream to the communication unit 1320 of the decoding apparatus 1300.

In step 3550, the processing unit 1310 of the decoding apparatus 1300 may extract a result of transformation.

In operation 3560, the processing unit 1310 of the decoding apparatus 1300 may perform inverse transformation related to the target block.

In operation 3570, the processing unit 1310 of the decoding apparatus 1300 may perform prediction related to the target block.

The specific functions of steps 3510, 3520, 3530, 3540, 3550, 3560 and 3570 and the specific objects of predictions, transforms and inverse transforms in steps 3510, 3520, 3560 and 3570 are described in detail below. do.

When divided blocks are units of transformation and inverse transformation

In step 3510, the processing unit 1210 may generate a residual block for the target block by performing prediction on the target block.

In step 3520, the processing unit 1210 may perform transformation in units of divided blocks. In other words, the processing unit 1210 may generate divided residual blocks by dividing the residual block, and may generate coefficients of the divided block by performing transform on each of the divided residual blocks.

In the following, transform may be interpreted as including quantization and in addition to transform. The inverse transformation may be interpreted as including inverse quantization, followed by inverse transformation. Also, coefficients may be interpreted as meaning transform and quantized coefficients.

A result of the transformation of step 3530 may include coefficients of a plurality of partitioned blocks.

In operation 3560, the processing unit 1310 may perform inverse transformation in units of divided blocks using coefficients of the divided blocks. In other words, the processing unit 1210 may generate a reconstructed partitioned residual block by performing an inverse transform on coefficients of the partitioned block.

A plurality of reconstructed divided residual blocks of a plurality of divided blocks may constitute a reconstructed residual block of a target block. Alternatively, the reconstructed residual block for the target block may include a plurality of reconstructed divided residual blocks.

In step 3570, the processing unit 1310 may generate a prediction block for the target block by performing prediction on the target block, and may generate a reconstructed block by summing the prediction block and the reconstructed residual block. A reconstructed block may include reconstructed samples.

In one embodiment, the TU splitting indicator may indicate whether transform and inverse transform are performed in units of divided blocks. For example, the name of the TU splitting indicator may be "TUsplitFlag".

The TU splitting indicator may be signaled through a bitstream.

In one embodiment, when the value of the division indicator of the upper block is a second predefined value, the target block is divided into a plurality of divided blocks in steps of transform and inverse transform, and transform and inverse transform the divided block. Whether or not this is performed may be signaled by the TU splitting indicator.

In one embodiment, when the value of the splitting indicator of the upper block is the second predefined value and the value of the splitting indicator of the target block is the first predefined value, the target block is configured to perform a plurality of steps of transformation and inverse transformation. It is divided into divided blocks, and whether or not transform and inverse transform are performed on the divided blocks may be signaled by a TU division indicator.

In one embodiment, when the shape and/or shape of the target block is the shape and/or shape to which division is applied, the target block is divided into a plurality of divided blocks in steps of transform and inverse transform, and the divided block Whether transformation and inverse transformation are performed may be signaled by the TU division indicator.

Here, the shape and/form to which the division is applied may be the shape and/form described as the division of the target block in the above-described other embodiments, such as a non-square shape. Alternatively, the shape and/or shape to which division is applied may mean including the states and/or conditions described as the division of the target block in the above-described other embodiments. The same applies below.

In one embodiment, when the value of the splitting indicator of the upper block is the second predefined value, the target block may be split into a plurality of square split blocks in steps of transformation and inverse transformation, and the split blocks Transformation and inverse transformation may be performed on .

In one embodiment, when the value of the splitting indicator of the upper block is the second predefined value and the value of the splitting indicator of the target block is the first predefined value, the target block is a square shape in the steps of transform and inverse transform. It may be divided into a plurality of divided blocks, and transformation and inverse transformation may be performed on the divided blocks.

In one embodiment, when the shape and/or shape of the target block is the shape and/or shape to which division is applied, the target block may be divided into a plurality of divided blocks in steps of transform and inverse transform, and Transformation and inverse transformation may be performed on the block.

When divided blocks are units of transform, inverse transform, and prediction

In step 3510, the processing unit 1210 may perform prediction in units of divided blocks. In other words, the processing unit 1210 may generate a partitioned residual block for the partitioned block by performing prediction on the partitioned block.

In one embodiment, prediction may be intra prediction.

In step 3520, the processing unit 1210 may perform transformation in units of divided blocks. In other words, the processing unit 1210 may generate coefficients of the divided block by performing transform on the divided residual block.

A result of the transformation of step 3530 may include coefficients of a plurality of partitioned blocks.

In step 3560, the processing unit 1310 may perform inverse transformation in units of divided blocks. In other words, the processing unit 1210 may generate a reconstructed partitioned residual block by performing an inverse transform on coefficients of the partitioned residual block.

In step 3570, the processing unit 1310 may perform prediction in units of divided blocks. In other words, the processing unit 1310 may generate a partitioned prediction block by performing prediction on the partitioned block, and may generate a partitioned reconstructed block by summing the partitioned prediction block and the reconstructed residual block.

The divided reconstructed blocks of the plurality of divided blocks may constitute a reconstructed block for the target block. Alternatively, the reconstructed block for the target block may include divided reconstructed blocks. A reconstructed block may include reconstructed samples.

In one embodiment, the PU splitting indicator may indicate whether prediction, transformation, and inverse transformation are performed in units of divided blocks. For example, the name of the PU splitting indicator may be "Intra_PU_SplitFlag".

The PU splitting indicator may be signaled through a bitstream.

In one embodiment, when the value of the division indicator of the upper block is the second predefined value, the target block is divided into a plurality of divided blocks in the prediction step, and prediction, transformation and inverse transformation are performed on the divided block. Whether or not to be performed may be signaled by the PU splitting indicator.

In one embodiment, when the value of the splitting indicator of the upper block is the second predefined value and the value of the splitting indicator of the current block is the first predefined value, the target block is a plurality of split blocks in the prediction step. It is divided into , and whether prediction, transformation, and inverse transformation are performed on the divided block may be signaled by the PU division indicator.

In one embodiment, when the shape and/or shape of the target block is the shape and/or shape to which division is applied, the target block is divided into a plurality of divided blocks in the prediction step, and the divided blocks are predicted; Whether transformation and inverse transformation are performed may be signaled by the PU splitting indicator.

In one embodiment, when the value of the division indicator of the upper block is the second predefined value, the target block may be divided into a plurality of divided blocks in a prediction step, and prediction, transformation and An inverse transformation may be performed.

In one embodiment, when the value of the division indicator of the upper block is the second predefined value and the value of the division indicator of the target block is the first predefined value, the target block is divided into a plurality of squares in the prediction step. blocks, and prediction, transformation, and inverse transformation may be performed on the divided blocks.

In one embodiment, when the shape and/or shape of the target block is the shape and/or shape to which division is applied, the target block may be divided into a plurality of divided blocks in the prediction step, and for the divided block Prediction, transformation and inverse transformation can be performed.

When the divided blocks are units of prediction and the target block is a unit of transformation and inverse transformation

In step 3510, the processing unit 1210 may perform prediction in units of divided blocks. In other words, the processing unit 1210 may generate a partitioned residual block for the partitioned block by performing prediction on the partitioned block.

A divided residual block of a plurality of divided blocks may constitute a residual block of a target block.

In step 3520, the processing unit 1210 may perform transformation in units of target blocks. For example, the processing unit 1210 may construct a residual block of a target block using divided residual blocks of a plurality of divided blocks. Alternatively, the residual block of the target block may include divided residual blocks of a plurality of divided blocks.

The processor 120 may generate coefficients of the target block by performing transform on the residual block of the target block.

A transform result of step 3530 may include coefficients of the target block.

In operation 3560, the processing unit 1310 may perform inverse transformation in units of target blocks using coefficients of target blocks. In other words, the processing unit 1210 may generate a reconstructed residual block by performing an inverse transform on the coefficients of the target block.

The reconstructed residual block may constitute a plurality of reconstructed divided residual blocks. Alternatively, the processing unit 1310 may generate a plurality of reconstructed divided residual blocks by dividing the reconstructed residual block. Alternatively, the reconstructed residual block may include a plurality of reconstructed divided residual blocks.

In step 3570, the processing unit 1310 may perform prediction in units of divided blocks.

In other words, the processing unit 1210 may generate a partitioned prediction block for the partitioned block by performing prediction on the partitioned block, and the partitioned block reconstructed by summing the partitioned prediction block and the reconstructed partitioned residual block. can create

As prediction is performed on the divided blocks, different prediction modes may be applied to each of the plurality of divided blocks.

A plurality of reconstructed divided blocks of a plurality of divided blocks may constitute a reconstructed block of a target block. Alternatively, a reconstructed block for the target block may include a plurality of reconstructed divided blocks.

In one embodiment, the TU merge PU splitting indicator may indicate whether prediction is performed in units of divided blocks, and transformation and inverse transformation are performed in units of target blocks. For example, the name of the TU merge PU splitting indicator may be "TU_Merge_PU_splitFlag".

The TU merge PU splitting indicator may be signaled through a bitstream.

In one embodiment, when the value of the split indicator of the upper block is the second predefined value, transform and inverse transform are performed on the target block, and whether or not prediction is performed on the split block is determined by the TU merge PU split indicator. can be signaled by

In one embodiment, when the value of the division indicator of the upper block is the second predefined value and the value of the division indicator of the target block is the first predefined value, transformation and inverse transformation are performed on the target block, and division is performed. Whether or not prediction is performed on the TU merge PU splitting indicator may be signaled.

In one embodiment, when the shape and / or shape of the target block is the shape and / form to which division is applied, transform and inverse transform are performed on the target block, and whether prediction is performed on the divided block is determined by TU merge. It can be signaled by the PU splitting indicator.

In one embodiment, when the value of the split indicator of the upper block is the second predefined value, prediction may be performed on the split block, and transformation on the target block may be performed after prediction on the split blocks. It can be. In addition, when the value of the division indicator of the upper block is a second predefined value, inverse transformation may be performed on the target block, and predictions on divided blocks may be performed after inverse transformation on the target block, A reconstruction sample for the target block may be generated.

In one embodiment, when the value of the splitting indicator of the upper block is the second predefined value and the value of the splitting indicator of the target block is the first predefined value, prediction may be performed on the split block; After prediction of the divided blocks, transformation of the target block may be performed. In addition, when the value of the split indicator of the upper block is the second predefined value and the value of the split indicator of the target block is the first predefined value, inverse transformation may be performed on the target block, and inverse transformation on the target block may be performed. After , predictions on divided blocks may be performed, and a reconstructed sample for the target block may be generated.

In one embodiment, when the shape and/or shape of the target block is the shape and/or shape to which segmentation is applied, prediction may be performed on the segmented block, and after prediction of the segmented blocks, the target block Conversion can be performed. In addition, when the shape and/or shape of the target block is the shape and/or shape to which division is applied, inverse transformation may be performed on the target block, and predictions on the divided blocks may be performed after the inverse transformation on the target block is performed. and a reconstruction sample for the target block may be generated.

In the foregoing embodiments, the methods are described on the basis of a flow chart as a series of steps or units, but the present invention is not limited to the order of steps, and some steps may occur in a different order or concurrently with other steps as described above. can In addition, those skilled in the art will understand that the steps shown in the flow chart are not exclusive, that other steps may be included, or that one or more steps of the flow chart may be deleted without affecting the scope of the present invention. You will understand.

Embodiments according to the present invention described above may be implemented in the form of program instructions that can be executed through various computer components and recorded on a computer-readable recording medium. The computer readable recording medium may include program instructions, data files, data structures, etc. alone or in combination. Program instructions recorded on the computer-readable recording medium may be specially designed and configured for the present invention, or may be known and usable to those skilled in the art of computer software. Examples of computer-readable recording media include magnetic media such as hard disks, floppy disks and magnetic tapes, optical recording media such as CD-ROMs and DVDs, and magneto-optical media such as floptical disks. media), and hardware devices specially configured to store and execute program instructions, such as ROM, RAM, flash memory, and the like. Examples of program instructions include high-level language codes that can be executed by a computer using an interpreter or the like as well as machine language codes such as those produced by a compiler. The hardware device may be configured to act as one or more software modules to perform processing according to the present invention and vice versa.

In the above, the present invention has been described by specific details such as specific components and limited embodiments and drawings, but these are provided to help a more general understanding of the present invention, and the present invention is not limited to the above embodiments. , Those skilled in the art to which the present invention pertains may seek various modifications and variations from these descriptions.

Therefore, the spirit of the present invention should not be limited to the above-described embodiments, and not only the claims described later, but also all modifications equivalent or equivalent to these claims belong to the scope of the spirit of the present invention. will do it

Claims (26)

determining whether to divide a target coding unit; and
generating four divided blocks by dividing the target coding unit in the horizontal direction when it is determined to perform the division in the horizontal direction;
including,
The vertical length of the target coding unit is 4 times the vertical length of each block of the 4 divided blocks,
The decoding method of claim 1 , wherein the division of the target coding unit into the four divided blocks is performed based on a horizontal length of the target coding unit and a vertical length of the target coding unit. According to claim 1,
Whether or not to divide is determined based on the shape of the target coding unit,
The decoding method of claim 1 , wherein the shape is one of square and non-square. According to claim 1,
The decoding method of determining whether to perform the division based on the depth of the target coding unit. According to claim 1,
The decoding method of determining the split shape based on a vertical length of the target coding unit and a horizontal length of the target coding unit. According to claim 1,
The decoding method in which the division is determined based on a block division indicator. delete According to claim 5,
When the block division indicator is not signaled through a bitstream, the decoding method determines the division according to a condition of using information related to the target coding unit. delete delete delete delete delete delete determining whether to divide a target coding unit; and
generating four divided blocks by dividing the target coding unit in the horizontal direction when it is determined to perform the division in the horizontal direction;
including,
The vertical length of the target coding unit is 4 times the vertical length of each block of the 4 divided blocks,
The encoding method of claim 1 , wherein the division of the target coding unit into the four divided blocks is performed based on a horizontal length of the target coding unit and a vertical length of the target coding unit. According to claim 14,
The encoding method of determining the split type based on a vertical length of the target coding unit and a horizontal length of the target coding unit. According to claim 14,
Generating a block division indicator indicating the division
A coding method further comprising a. A recording medium on which a bitstream generated by the encoding method according to claim 14 is recorded. A computer-readable recording medium storing a bitstream,
The bitstream is
Coded information about the target coding unit
including,
Decoding of the target coding unit is performed using the encoded information;
Whether to split the target coding unit is determined;
When it is determined to perform the division in the horizontal direction, four divided blocks are generated by dividing the target coding unit in the horizontal direction;
The vertical length of the target coding unit is 4 times the vertical length of each block of the 4 divided blocks,
The division of the target coding unit into the four divided blocks is performed based on a horizontal length of the target coding unit and a vertical length of the target coding unit. According to claim 18,
A computer-readable recording medium for recording a bitstream in which the division type is determined based on a vertical length of the target coding unit and a horizontal length of the target coding unit. According to claim 18,
The bitstream is
Block division indicator used for the division
A computer-readable recording medium for recording a bitstream further comprising a. delete delete delete delete delete delete

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