KR102511581B1 - Method and apparatus for encoding/decoding image and recording medium for storing bitstream - Google Patents

Abstract

The present invention relates to a video encoding and decoding method. An image decoding method for this includes generating a first prediction block of the current block using motion information of the current block, and generating at least one prediction block of the current sub-block by using motion information of at least one neighboring sub-block. Generating a second prediction block of a block and generating a final prediction block based on a weighted sum of a first prediction block of the current block and a second prediction block of the at least one current sub-block. there is.

Description

Video encoding/decoding method, device, and recording medium storing bitstream

The present invention relates to a video encoding/decoding method, apparatus, and recording medium storing a bitstream. Specifically, the present invention relates to an image encoding/decoding method and apparatus using overlapped block motion compensation.

Recently, demand for high-resolution and high-quality images such as high definition (HD) images and ultra high definition (UHD) images is increasing in various application fields. As image data becomes higher resolution and higher quality, the amount of data increases relatively compared to existing image data. Therefore, when image data is transmitted using a medium such as an existing wired/wireless broadband line or stored using an existing storage medium, transmission cost and Storage costs increase. In order to solve these problems caused by high-resolution and high-quality video data, high-efficiency video encoding/decoding technology for video with higher resolution and quality is required.

An inter-prediction technique for predicting pixel values included in the current picture from pictures before or after the current picture as an image compression technique, an intra-prediction technique for predicting pixel values included in the current picture using pixel information within the current picture, There are various technologies such as transformation and quantization technology for compressing the energy of the residual signal, and entropy encoding technology that assigns short codes to values with high frequency of occurrence and long codes to values with low frequency of occurrence. Image data can be effectively compressed and transmitted or stored.

Conventional image encoding/decoding methods and apparatuses use only motion information of limited neighboring blocks when compensating overlapped block motion, so there is a limit to improving encoding efficiency.

The present invention may provide a method and apparatus for performing overlapped block motion compensation by increasing the number of motion information of neighboring blocks in order to improve encoding/decoding efficiency of an image.

According to the present invention, a video decoding method includes generating a first prediction block of a current block using motion information of the current block; Generating a second prediction block of at least one current sub-block using motion information of at least one neighboring sub-block of the current sub-block and the first prediction block of the current block and the at least one current sub-block It may include generating a final prediction block based on a weighted sum of second prediction blocks of .

In the image decoding method, the neighboring sub-blocks may include neighboring sub-blocks of sub-blocks of the corresponding location block temporally corresponding to the current block.

In the video decoding method, the generating of the second prediction block may include, when the current sub-block is not included in the left boundary area and the top boundary area of the current block, at least one of the sub-blocks of the corresponding location block. At least one second prediction block may be generated using motion information of neighboring sub-blocks of .

In the video decoding method, the generating of the second prediction block may include, when the current sub-block is not included in the left boundary region and the upper boundary region of the current block, a merge list and a motion vector list of the current block. A second prediction block may be generated using motion information included in at least one of the prediction blocks.

In the image decoding method, the generating of the second prediction block may include the generation of at least one neighboring sub-block only when the current sub-block is included in at least one of a left boundary region and an upper boundary region of the current block. At least one second prediction block may be generated using motion information.

In the video decoding method, the generating of the second prediction block may include, when the current sub-block is included in a left boundary region of the current block, a left neighboring sub-block, an upper-left neighboring sub-block, and At least one second prediction block is generated using motion information of at least one of the lower-left neighboring sub-blocks, and when the current sub-block is included in the upper boundary area of the current block, the upper-side neighboring lower part of the current sub-block At least one second prediction block may be generated using motion information of at least one of the block, an upper-left neighboring sub-block, and a lower-right neighboring sub-block.

In the video decoding method, the generating of the second prediction block may include, when the current sub-block is not included in the left boundary region and the top boundary region of the current block, a sub-block adjacent to an upper end of the current sub-block; Using motion information of at least one of a left peripheral sub-block, a lower peripheral sub-block, a right peripheral sub-block, an upper-left peripheral sub-block, a lower-left peripheral sub-block, a lower-right peripheral sub-block, and an upper-right peripheral sub-block, at least one second Prediction blocks can be created.

In the video decoding method, the generating of the second prediction block may include deriving motion information of at least one neighboring sub-block of the current sub-block in a predetermined order, and deriving the derived at least one motion information. At least one second prediction block may be generated using

In the video decoding method, the generating of the final prediction block may include setting weights for each sample of the first prediction block and the second prediction block according to positions of neighboring sub-blocks used when generating the second prediction block. A weighted sum can be performed by applying it differently.

In the video decoding method, the generating of the final prediction block may include, when there are a plurality of second prediction blocks of the current sub-block, a gap between the first prediction block of the current block and the second prediction block of the current sub-block. The final prediction block may be generated by simultaneously summing the weighted sums.

According to the present invention, an image encoding method includes generating a first prediction block of a current block using motion information of the current block; Generating a second prediction block of at least one current sub-block using motion information of at least one neighboring sub-block of the current sub-block and the first prediction block of the current block and the at least one current sub-block It may include generating a final prediction block based on a weighted sum of second prediction blocks of .

In the video encoding method, the neighboring sub-blocks may include neighboring sub-blocks of sub-blocks of the corresponding location block temporally corresponding to the current block.

In the video encoding method, the generating of the second prediction block may include, when the current sub-block is not included in the left boundary area and the top boundary area of the current block, at least one of the sub-blocks of the corresponding location block. At least one second prediction block may be generated using motion information of neighboring sub-blocks of .

In the video encoding method, the generating of the second prediction block may include, when the current sub-block is not included in the left boundary region and the upper boundary region of the current block, a merge list and a motion vector list of the current block. A second prediction block may be generated using motion information included in at least one of the prediction blocks.

In the image encoding method, the generating of the second prediction block may include the generation of at least one neighboring sub-block only when the current sub-block is included in at least one of a left boundary region and an upper boundary region of the current block. At least one second prediction block may be generated using motion information.

In the video encoding method, the generating of the second prediction block may include, when the current sub-block is included in a left boundary region of the current block, a left neighboring sub-block of the current sub-block, an upper-left neighboring sub-block, and At least one second prediction block is generated using motion information of at least one of the lower-left neighboring sub-blocks, and when the current sub-block is included in the upper boundary area of the current block, the upper-side neighboring lower part of the current sub-block At least one second prediction block may be generated using motion information of at least one of the block, an upper-left neighboring sub-block, and a lower-right neighboring sub-block.

In the video encoding method, the generating of the second prediction block may include, when the current sub-block is not included in the left boundary area and the top boundary area of the current block, an upper end neighboring sub-block of the current sub-block; Using motion information of at least one of a left peripheral sub-block, a lower peripheral sub-block, a right peripheral sub-block, an upper-left peripheral sub-block, a lower-left peripheral sub-block, a lower-right peripheral sub-block, and an upper-right peripheral sub-block, at least one second Prediction blocks can be created.

In the video encoding method, the generating of the second prediction block may include deriving motion information of at least one neighboring sub-block of the current sub-block in a predetermined order, and deriving the derived at least one motion information. At least one second prediction block may be generated using

In the video encoding method, the generating of the final prediction block may include setting weights for each sample of the first prediction block and the second prediction block according to positions of neighboring sub-blocks used when generating the second prediction block. A weighted sum can be performed by applying it differently.

In the video encoding method, the generating of the final prediction block may include, when there are a plurality of second prediction blocks of the current sub-block, a gap between the first prediction block of the current block and the second prediction block of the current sub-block. The final prediction block may be generated by simultaneously summing the weighted sums.

The recording medium of the present invention includes the steps of generating a first prediction block of the current block using motion information of the current block; Generating a second prediction block of at least one current sub-block using motion information of at least one neighboring sub-block of the current sub-block and the first prediction block of the current block and the at least one current sub-block A bitstream generated by an image encoding method including the step of generating a final prediction block based on a weighted sum of second prediction blocks may be stored.

According to the present invention, a video encoding/decoding method and apparatus with improved compression efficiency can be provided.

According to the present invention, encoding and decoding efficiency of an image can be improved.

According to the present invention, calculation complexity of an image encoder and a decoder can be reduced.

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 for explaining an embodiment of an inter-screen prediction process.
5 is a flowchart illustrating an image encoding method according to an embodiment of the present invention.
6 is a flowchart illustrating an image decoding method according to an embodiment of the present invention.
7 is a flowchart illustrating an image encoding method according to another embodiment of the present invention.
8 is a flowchart illustrating an image decoding method according to another embodiment of the present invention.
9 is a diagram for explaining an example of deriving a spatial motion vector candidate of a current block.
10 is a diagram for explaining an example of deriving a temporal motion vector candidate of a current block.
11 is a diagram for explaining an example in which a spatial merge candidate is added to a merge candidate list.
12 is a diagram for explaining an example in which a temporal merge candidate is added to a merge candidate list.
13 is a diagram for explaining an example in which overlapped block motion compensation is performed in sub-block units.
14 is a diagram for explaining an example in which motion compensation for overlapping blocks is performed using motion information of a lower block of a corresponding block.
15 is a diagram for explaining an example in which overlapped block motion compensation is performed using motion information of a block adjacent to a boundary region of a reference block.
16 is a diagram for explaining an example in which overlapped block motion compensation is performed in units of sub-block groups.
17 is a diagram for explaining an example of the number of pieces of motion information used for overlapping block motion compensation.
18 and 19 are diagrams for explaining a sequence of deriving motion information used to generate a second prediction block.
20 is a diagram for explaining an example of determining whether motion information usable for generation of a second prediction block is determined by comparing the POC of a reference image of a current sub-block with POCs of reference images of neighboring sub-blocks.
21 is a diagram for explaining an embodiment of applying a weight when calculating a weighted sum of a first prediction block and a second prediction block.
22 is a diagram for explaining an embodiment in which different weights are applied according to sample positions within blocks when calculating a weighted sum of a first prediction block and a second prediction block.
23 is a diagram for explaining an embodiment in which a weighted sum of a first prediction block and a second prediction block is cumulatively calculated in a predetermined order when performing overlapping block motion compensation.
24 is a diagram for explaining an embodiment in which a weighted sum of a first prediction block and a second prediction block is calculated during overlapped block motion compensation.
25 is a flowchart illustrating an image decoding method according to an embodiment of the present invention.

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. 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. 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.

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 of the present invention is referred to as “connected” or “connected” to another component, it may be directly connected or connected to the other component, but there may be other components in the middle. It should be understood that it may be On the other hand, when an element is referred to as “directly connected” or “directly connected” to another element, it should be understood that no other element exists in the middle.

Components appearing in the embodiments of the present invention are shown independently to represent different characteristic functions, and do not mean that each component is composed of separate hardware or a single software component. That is, each component is listed and included as each component for convenience of explanation, and at least two components of each component can be combined to form a single component, or one component can be divided into a plurality of components to perform a function, and each of these components can be divided into a plurality of components. Integrated embodiments and separated embodiments of 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.

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 means that additional configurations may be included in the practice of the present invention or the scope of the technical spirit of the present invention.

Some of the components of the present invention are not essential components that perform essential functions in the present invention, but may be optional components for improving performance. The present invention can be implemented by including only components essential to implement the essence of the present invention, excluding components used for performance improvement, and a structure including only essential components excluding optional components used for performance improvement. Also included in the scope of the present invention.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described concretely with reference to drawings. In describing the embodiments of this specification, 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, and the same reference numerals will be used for the same components in the drawings. and duplicate descriptions of the same components are omitted.

In addition, hereinafter, an image may mean one picture constituting a video, and may also represent a 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 Here, a picture may have the same meaning as an image.

Glossary of Terms

Encoder: Means a device that performs encoding.

Decoder: Means a device that performs decoding.

Block: MxN array of Samples. Here, M and N denote positive integer values, and a block may denote a two-dimensional array of samples. A block may mean a unit. The current block may mean an encoding target block to be encoded during encoding and a decoding target block to be decoded during decoding. Also, the current block may be at least one of a coding block, a prediction block, a residual block, and a transform block.

Sample: This is the basic unit constituting a block. It can be expressed as a value from 0 to 2 ^Bd - 1 according to the bit depth (B _d ). In the present invention, a sample may be used as the same meaning as a pixel or a pixel.

Unit: Means a unit of video encoding and decoding. In encoding and decoding of an image, a unit may be a region obtained by dividing one image. Also, a unit may refer to a divided unit when encoding or decoding an image is divided into subdivided units. In encoding and decoding of an image, a predefined process may be performed for each unit. One unit can be further divided into sub-units having a smaller size relative to the unit. According to function, units are Block, Macroblock, Coding Tree Unit, Coding Tree Block, Coding Unit, Coding Block, and Prediction. It may mean a prediction unit, a prediction block, a residual unit, a residual block, a transform unit, a transform block, and the like. In addition, a unit may mean that it includes a Luma component block, a Chroma component block corresponding thereto, and a syntax element for each block to be referred to as a block. The unit may have various sizes and shapes, and in particular, the shape of the unit may include not only a rectangle but also a geometric figure that can be expressed in two dimensions, such as a square, a trapezoid, a triangle, and a pentagon. Also, 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.

Coding Tree Unit: It consists of two chrominance components (Cb, Cr) coding tree blocks related to one luminance component (Y) coding tree block. Also, it may mean including the above blocks and syntax elements for each block. Each coding tree unit may be split using one or more division schemes such as a quad tree or a binary tree to form subunits such as a coding unit, a prediction unit, and a transform unit. It can be used as a term to refer to a pixel block that is a processing unit in the decoding/coding process of an image, like segmentation of an input image.

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

Reconstructed Neighbor Block: Refers to a neighboring block that has already been spatially/temporally encoded or decoded around the current block. In this case, the reconstructed neighboring block may mean a reconstructed neighboring unit. The reconstructed spatial neighboring block may be a block in the current picture and already reconstructed through encoding and/or decoding. The reconstructed temporal neighboring block may be a reconstructed block in the same position as the current block of the current picture within the reference picture or a neighboring block thereof.

Unit depth (Depth): Means the degree to which the unit is divided. In a tree structure, the root node has the shallowest depth and the leaf node has the deepest depth. Also, when a unit is expressed in a tree structure, a level at which a unit exists may mean a unit depth.

Bitstream: means a string of bits including coded image information.

Parameter Set: Corresponds to header information among structures within a bitstream. At least one of a video parameter set, a sequence parameter set, a picture parameter set, and an adaptation parameter set may be included in the parameter set. Also, the parameter set may include slice header and tile header information.

Parsing: Determining the value of a syntax element by entropy decoding a bitstream, or entropy decoding itself.

Symbol: It may mean at least one of a syntax element of a unit to be coded/decoded, a coding parameter, a value of a transform coefficient, and the like. Also, a symbol may mean an object of entropy encoding or a result of entropy decoding.

Prediction Unit: Refers to a basic unit when performing prediction such as inter-prediction, intra-prediction, inter-screen compensation, intra-screen compensation, and motion compensation. One prediction unit may be divided into a plurality of small-sized partitions or lower prediction units.

Prediction Unit Partition: Means a form in which a prediction unit is divided.

Reference Picture List: Refers to a list including one or more reference pictures used for inter-prediction or motion compensation. The type of reference image list may include LC (List Combined), L0 (List 0), L1 (List 1), L2 (List 2), L3 (List 3), etc. A list may be used.

Inter prediction indicator: This may indicate an inter prediction direction (unidirectional prediction, bidirectional prediction, etc.) of the current block. Alternatively, it may mean the number of reference images used when generating the prediction block of the current block. Alternatively, it may mean the number of prediction blocks used when inter-prediction or motion compensation is performed on the current block.

Reference Picture Index: Indicates an index indicating a specific reference picture in a reference picture list.

Reference Picture: This may refer to a picture referenced by a specific block for inter-picture prediction or motion compensation.

Motion Vector: A 2D vector used for inter-screen prediction or motion compensation, and may mean an offset between an encoding/decoding target image and a reference image. For example, (mvX, mvY) may represent a motion vector, mvX may represent a horizontal component, and mvY may represent a vertical component.

Motion Vector Candidate: When a motion vector is predicted, it means a block that becomes a prediction candidate or a motion vector of the block. Also, the motion vector candidate may be included in the motion vector candidate list.

Motion vector candidate list: This may mean a list constructed using motion vector candidates.

Motion vector candidate index: An indicator indicating a motion vector candidate in the motion vector candidate list. It can also be referred to as an index of a motion vector predictor.

Motion Information: At least among reference picture list information, reference picture, motion vector candidate, motion vector candidate index, merge candidate, merge index, etc. as well as motion vector, reference picture index, inter prediction indicator It may mean information including one.

Merge Candidate List: A list constructed using merge candidates.

Merge Candidate: A spatial merge candidate, a temporal merge candidate, a combined merge candidate, a combined predictive merge candidate, a zero merge candidate, and the like. A merge candidate may include motion information such as an inter-picture prediction indicator, a reference picture index for each list, and a motion vector.

Merge Index: Means information indicating a merge candidate in a merge candidate list. Also, the merge index may indicate a block from which a merge candidate is derived, among blocks reconstructed that are spatially/temporally adjacent to the current block. Also, the merge index may indicate at least one of motion information of merge candidates.

Transform Unit: Refers to a basic unit when encoding/decoding a residual signal such as transform, inverse transform, quantization, inverse quantization, and transform coefficient encoding/decoding is performed. One transform unit may be divided into a plurality of smaller transform units.

Scaling: A process of multiplying a transform coefficient level by a factor. Transform coefficients can be generated as a result of scaling for transform coefficient levels. Scaling can also be called dequantization.

Quantization parameter: This may mean a value used when generating a transform coefficient level for transform coefficients in quantization. Alternatively, it may mean a value used when generating a transform coefficient by scaling a transform coefficient level in inverse quantization. The quantization parameter may be a value mapped to a quantization step size.

Residual quantization parameter (Delta Quantization Parameter): Means a difference between a predicted quantization parameter and a quantization parameter of a unit to be encoded/decoded.

Scan: Refers to a method of arranging the order of coefficients in a block or matrix. For example, sorting a 2D array into a 1D array is called a scan. Alternatively, arranging a one-dimensional array into a two-dimensional array may also be called scan or inverse scan.

Transform Coefficient: means a coefficient value generated after performing a transform in an encoder. Alternatively, it may mean a coefficient value generated after performing at least one of entropy decoding and inverse quantization in a decoder. A quantized level obtained by applying quantization to a transform coefficient or a residual signal or a quantized transform coefficient level also means a transform coefficient. can be included in

Quantized Level: means a value generated by performing quantization on transform coefficients or residual signals in an encoder. Alternatively, it may mean a value to be subjected to inverse quantization before performing inverse quantization in a decoder. Similarly, a quantized transform coefficient level resulting from transform and quantization may also be included in the meaning of the quantized level.

Non-zero transform coefficient: means a transform coefficient whose magnitude is not 0 or a transform coefficient level whose magnitude is not 0.

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

Quantization Matrix Coefficient: Means each element in a quantization matrix. Quantization matrix coefficients may also be referred to as matrix coefficients.

Default Matrix: Means a predetermined quantization matrix predefined in an encoder and a decoder.

Non-default matrix: A quantization matrix that is not predefined in an encoder and a decoder and is signaled by a user.

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 device 100 may sequentially encode one or more images.

Referring to FIG. 1 , the encoding apparatus 100 includes a motion estimation unit 111, a motion compensation unit 112, an intra prediction unit 120, a switch 115, a subtractor 125, a transform unit 130, and a quantization unit. It may include a unit 140, an entropy encoding unit 150, an inverse quantization unit 160, an inverse transform unit 170, an adder 175, a filter unit 180, and a reference picture buffer 190.

The encoding apparatus 100 may perform encoding on an input image in an intra mode and/or an inter mode. Also, the encoding device 100 may generate a bitstream through encoding of an input image and output the generated bitstream. The generated bitstream may be stored in a computer readable recording medium or streamed through a wired/wireless transmission medium. When the intra mode is used as the prediction mode, the switch 115 may be switched to intra, and when the inter mode is used as the prediction mode, the switch 115 may be switched to inter. Here, the intra mode may mean an intra prediction mode, and the inter mode may mean an inter prediction mode. The encoding apparatus 100 may generate a prediction block for an input block of an input image. Also, the encoding apparatus 100 may encode a residual between the input block and the prediction block after the prediction block is generated. The input image may be referred to as a current image that is a current encoding target. The input block may be referred to as a current block that is a current encoding target or an encoding target block.

When the prediction mode is the intra mode, the intra prediction unit 120 may use pixel values of blocks already encoded/decoded around the current block as reference pixels. The intra predictor 120 may perform spatial prediction using a reference pixel and generate prediction samples for an input block through spatial prediction. Here, intra prediction may mean prediction within a screen.

When the prediction mode is the inter mode, the motion predictor 111 may search for a region that best matches the input block from the reference image in the motion prediction process, and derive a motion vector using the searched region. . A reference image may be stored in the reference picture buffer 190 .

The motion compensation unit 112 may generate a prediction block by performing motion compensation using a motion vector. Here, inter prediction may mean inter prediction or motion compensation.

When the motion vector value does not have an integer value, the motion estimation unit 111 and the motion compensation unit 112 may generate a prediction block by applying an interpolation filter to a partial region in the reference image. . In order to perform inter-prediction or motion compensation, the motion prediction and motion compensation methods of the prediction unit included in the coding unit based on the coding unit are skip mode, merge mode, and enhanced motion vector prediction ( It is possible to determine whether it is an Advanced Motion Vector Prediction (AMVP) mode or a current picture reference mode, and inter-picture prediction or motion compensation can be performed according to each mode.

The subtractor 125 may generate a residual block using a difference between the input 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 predicted 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 predicted signal. The residual block may be a residual signal in units of blocks.

The transform unit 130 may generate a transform coefficient by performing transform on the residual block, and may output the transform coefficient. 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 transform on the residual block.

A quantized level may be created by applying quantization to the transform coefficient or residual signal. Hereinafter, in the embodiments, the quantized level may also be referred to as a transform coefficient.

The quantization unit 140 may generate a quantized level by quantizing the transform coefficient or the residual signal according to a quantization parameter, and may output the 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 on the values calculated by the quantization unit 140 or the values of coding parameters calculated in the encoding process. Yes, and can output bitstreams. 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.

When entropy encoding is applied, a small number of bits are allocated to a symbol with a high probability of occurrence and a large number of bits are allocated to a symbol with a low probability of occurrence to represent the symbol, thereby reducing the number of bits for symbols to be coded. The size of the column may be reduced. The entropy encoding unit 150 may use an encoding method such as exponential Golomb, CAVLC (Context-Adaptive Variable Length Coding), or CABAC (Context-Adaptive Binary Arithmetic Coding) for entropy encoding. For example, the entropy encoding unit 150 may perform entropy encoding using a variable length coding/code (VLC) table. In addition, the entropy encoding unit 150 derives a binarization method of the target symbol and a probability model of the target symbol/bin, and then the derived binarization method, probability model, and context model Arithmetic encoding may be performed using

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

Coding parameters, such as syntax elements, may include not only information (flag, index, etc.) that is coded in the encoder and signaled to the decoder, but also information derived from the encoding or decoding process. It can mean necessary information. For example, unit/block size, unit/block depth, unit/block division information, unit/block division structure, quad tree division, binary tree division, binary tree division direction (horizontal or vertical direction), binary tree type division (symmetric division or asymmetric division), intra-prediction mode/direction, reference sample filtering method, prediction block filtering method, prediction block filter tab, prediction block filter coefficient, inter-prediction mode, Motion information, motion vector, reference image index, inter-prediction direction, inter-prediction indicator, reference image list, reference image, motion vector prediction candidate, motion vector candidate list, use of merge mode, merge candidate, merge candidate list, skip Whether to use (skip) mode, interpolation filter type, interpolation filter tab, interpolation filter coefficient, motion vector size, motion vector representation accuracy, transformation type, transformation size, information on whether to use the first-order transformation, whether to use the second-order transformation, first-order Transformation index, secondary transformation index, residual signal presence information, coded block pattern, coded block flag, quantization parameter, quantization matrix, whether to apply loop filter within a screen, loop filter coefficient within a screen , in-screen loop filter tab, in-screen loop filter shape/shape, deblocking filter applied or not, deblocking filter coefficients, deblocking filter tab, deblocking filter strength, deblocking filter shape/shape, adaptive sample offset applied or not, Adaptive Sample Offset Value, Adaptive Sample Offset Category, Adaptive Sample Offset Type, Adaptive Loop Filter Application, Adaptive Loop Filter Coefficient, Adaptive Loop Filter Tap, Adaptive Loop Filter Shape/Form, Binarization /Inverse binarization method, context model determination method, context model update method, whether regular mode is performed, whether bypass mode is performed, context bin, bypass bin, transform coefficient, transform coefficient level, transform coefficient level scanning method, image display/output order, slice identification information, A value of at least one of rice type, slice division information, tile identification information, tile type, tile division information, picture type, bit depth, and information on a luminance signal or color difference signal, or a combination thereof, may be included in the coding parameter.

Here, signaling the flag or index may mean that the encoder entropy-encodes the corresponding flag or index and includes it in a bitstream, and the decoder converts the corresponding flag or index from the bitstream. It may mean entropy decoding.

When the encoding apparatus 100 performs encoding through inter prediction, an encoded current image may be used as a reference image for another image to be processed later. Accordingly, the encoding device 100 may reconstruct or decode the encoded current image, and store the reconstructed or decoded image as a reference image.

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

The reconstruction block may pass through the filter unit 180 . The filter unit 180 may apply at least one of a deblocking filter, a sample adaptive offset (SAO), and an adaptive loop filter (ALF) to a reconstructed block or a reconstructed image. there is. 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 perform the deblocking filter, it may be determined whether to apply the deblocking filter to the current block based on pixels included in several columns or rows included in the block. When a deblocking filter is applied to a block, different filters may be applied according to the required deblocking filtering strength.

An appropriate offset value may be added to a pixel value to compensate for an encoding error using the sample adaptive offset. The sample-adaptive offset may correct an offset from an original image on a pixel-by-pixel basis for an image on which deblocking is performed. After dividing the pixels included in the image into a certain number of areas, a method of determining an area to be offset and applying the offset to the area or a method of applying the offset in consideration of edge information of each pixel may be used.

The adaptive loop filter may perform filtering based on a value obtained by comparing a reconstructed image and an original image. After dividing the pixels included in the image into predetermined groups, filtering may be performed differentially for each group by determining a filter to be applied to the corresponding group. Information related to whether to apply the adaptive loop filter may be signaled for each coding unit (CU), and the shape and filter coefficients of the adaptive loop filter to be applied may vary according to 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 . 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, a motion compensation 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 decoding on a bitstream in an intra mode or an inter mode. Also, the decoding apparatus 200 may generate a restored image or a decoded image through decoding and output the restored image or the decoded image.

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 decode the input bitstream to obtain a reconstructed residual block 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. A block to be decoded may be referred to as a current block.

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

The entropy decoding unit 210 may change a 1-dimensional vector form coefficient into a 2-dimensional block form through a transform coefficient scanning method in order to decode a transform coefficient level.

The quantized level may be inversely quantized in the inverse quantization unit 220 and inversely transformed in the inverse transformation unit 230 . The quantized level may be generated as a reconstructed residual block as a result of performing inverse quantization and/or inverse transformation. At this time, the inverse quantization unit 220 may apply a quantization matrix to the quantized level.

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 around the current block to be decoded.

When the inter mode is used, the motion compensation unit 250 may generate a prediction block by performing motion compensation using a motion vector and a reference image stored in the reference picture buffer 270 . When the motion vector value does not have an integer value, the motion compensator 250 may generate a prediction block by applying an interpolation filter to a partial region in the reference image. In order to perform motion compensation, it is possible to determine which of the skip mode, merge mode, AMVP mode, and current picture reference mode is the motion compensation method of the prediction unit included in the coding unit based on the coding unit, and each mode Accordingly, motion compensation may be performed.

The adder 255 may generate a reconstructed block by adding the reconstructed residual block and the prediction block. The filter unit 260 may apply at least one of a deblocking filter, a sample adaptive offset, and an adaptive loop filter to a reconstructed block or a reconstructed image. The filter unit 260 may output a reconstructed image. A reconstructed block or a reconstructed image may be stored in the reference picture buffer 270 and used for inter prediction.

3 is a diagram schematically illustrating a division structure of an image when encoding and decoding an image. 3 schematically illustrates an embodiment 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 coding unit may be used as a basic unit of image encoding/decoding. In addition, during video encoding/decoding, an encoding unit may be used as a unit in which an intra-screen mode and an inter-screen mode are distinguished. The coding unit may be a basic unit used for a process of prediction, transformation, quantization, inverse transformation, inverse quantization, or encoding/decoding of transform coefficients.

Referring to FIG. 3 , an image 300 is sequentially divided into units of largest coding units (LCUs), and a division structure is determined in units of LCUs. Here, LCU may be used in the same meaning as a coding tree unit (CTU). Division of a unit may mean division of a block corresponding to the unit. Block division information may include 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 partitioned with depth information based on a tree structure. Each divided sub-unit may have depth information. Depth information may be information representing the size of a CU and may be stored for each CU.

The division structure may refer to a distribution of Coding Units (CUs) within the LCU 310 . This distribution can be determined according to whether to divide one CU into a plurality of (positive integers of 2 or more including 2, 4, 8, 16, etc.) CUs. The horizontal size and vertical size of the CU created by splitting are half the horizontal size and half the vertical size of the CU before splitting, respectively, or a size smaller than the horizontal size and vertical size of the CU before splitting according to the number of splits. can have A CU can be recursively split into multiple CUs. 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, as described above, the LCU may be a coding unit having the largest coding unit size, and the SCU may be a coding unit having the smallest coding unit size. The division starts from the LCU 310, and the depth of the CU increases by 1 whenever the horizontal size and/or the vertical size of the CU are reduced by the division.

Also, 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, if the value of the division information is a first value, the CU may not be divided, and if the value of the division information is a second value, the CU may be divided.

Referring to FIG. 3, an LCU having a depth of 0 may be a 64x64 block. 0 may be the minimum depth. An SCU with a depth of 3 can be an 8x8 block. 3 may be the maximum depth. The CUs of the 32x32 block and the 16x16 block may be expressed as depth 1 and depth 2, respectively.

For example, when one coding unit is divided into 4 coding units, the horizontal and vertical sizes of the divided 4 coding units may be halved compared to the horizontal and vertical sizes of the coding unit before division. there is. For example, when a 32x32 coding unit is divided into 4 coding units, each of the divided 4 coding units may have a size of 16x16. When one coding unit is divided into four coding units, it can be said that the coding units are divided in a quad-tree form.

For example, when one coding unit is divided into two coding units, the horizontal or vertical size of the two divided coding units may be half of the horizontal or vertical size of the coding unit before being divided. . For example, when a coding unit having a size of 32x32 is vertically divided into two coding units, each of the two divided coding units may have a size of 16x32. When one coding unit is divided into two coding units, it can be said that the coding unit is divided in the form of a binary tree. The LCU 320 of FIG. 3 is an example of an LCU to which both quad-tree partitioning and binary tree partitioning are applied.

4 is a diagram for explaining an embodiment of an inter-screen prediction process.

The rectangle shown in FIG. 4 may represent an image. Also, arrows in FIG. 4 may indicate prediction directions. Each image may be classified into an I-picture (Intra Picture), a P-picture (Predictive Picture), a B-picture (Bi-predictive Picture), and the like according to an encoding type.

I-pictures can be coded through intra-prediction without inter-prediction. A P picture may be coded through inter prediction using only a reference picture existing in one direction (eg, forward direction or backward direction). A B picture may be coded through inter prediction using reference pictures existing in bidirectional directions (eg, forward and backward directions). Here, when inter-prediction is used, the encoder may perform inter-prediction or motion compensation, and the decoder may perform motion compensation corresponding thereto.

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

Inter-picture prediction or motion compensation may be performed using a reference picture and motion information.

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

A method of deriving motion information may be different according to the prediction mode of the current block. For example, prediction modes applied for inter-prediction may include AMVP mode, merge mode, skip mode, current picture reference mode, and the like. Here, the merge mode may be referred to as a motion merge mode.

For example, when AMVP is applied as a prediction mode, at least one of a motion vector of a reconstructed neighboring block, a motion vector of a collocated block, a motion vector of a block adjacent to the collocated block, and a (0, 0) motion vector is used as a motion vector. A motion vector candidate list may be generated by determining a motion vector candidate list. A motion vector candidate may be derived using the generated motion vector candidate list. Motion information of the current block may be determined based on the derived motion vector candidate. Here, 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 motion vector candidate, and a motion vector of a reconstructed neighboring block may be referred to as a spatial motion vector candidate. ) can be referred to as

The encoding apparatus 100 may calculate a motion vector difference (MVD) between the motion vector of the current block and the motion vector candidate, and entropy-encode the MVD. Also, the encoding apparatus 100 may entropy-encode the motion vector candidate index to generate a bitstream. The motion vector candidate index may indicate an optimal motion vector candidate selected from motion vector candidates included in the motion vector candidate list. The decoding apparatus 200 may entropy-decode a motion vector candidate index from a bitstream and select a motion vector candidate of a decoding target block from motion vector candidates included in a motion vector candidate list by using the entropy-decoded motion vector candidate index. . Also, the decoding apparatus 200 may derive the motion vector of the decoding target block through the sum of the entropy-decoded MVD and the motion vector candidate.

The bitstream may include a reference picture index indicating a reference picture. The reference image index may be entropy-encoded and signaled from the encoding apparatus 100 to the decoding apparatus 200 through a bitstream. The decoding apparatus 200 may generate a prediction block for a decoding target block based on the derived motion vector and reference image index information.

Another example of a motion information derivation method is a merge mode. Merge mode may mean merging of motions of a plurality of blocks. A merge mode may refer to a mode in which motion information of a current block is derived from motion information of neighboring blocks. When merge mode is applied, a merge candidate list may be generated using motion information of a reconstructed neighboring block and/or motion information of a collocated block. The motion information may include at least one of 1) a motion vector, 2) a reference image index, and 3) an inter-picture prediction indicator. Prediction indicators can be unidirectional (L0 prediction, L1 prediction) or bidirectional.

The merge candidate list may indicate a list in which motion information is stored. Motion information stored in the merge candidate list includes motion information of blocks adjacent to the current block (spatial merge candidate) and motion information of blocks collocated with the current block in the reference image (temporal merge candidate (spatial merge candidate)). temporal merge candidate)), new motion information generated by a combination of motion information already existing in the merge candidate list, and a zero merge candidate.

The encoding apparatus 100 may entropy-encode at least one of a merge flag and a merge index to generate a bitstream, and then signal the bitstream to the decoding apparatus 200 . The merge flag may be information indicating whether merge mode is to be performed for each block, and the merge index may be information about which block among neighboring blocks adjacent to the current block is merged with. For example, neighboring blocks of the current block may include at least one of a left neighboring block, an upper neighboring block, and a temporal neighboring block of the current block.

The skip mode may be a mode in which motion information of neighboring blocks is applied to the current block as it is. When the skip mode is used, the encoding apparatus 100 may entropy-encode information about which block motion information is to be used as the motion information of the current block and signal it to the decoding apparatus 200 through a bitstream. In this case, the encoding apparatus 100 may not signal a syntax element related to at least one of the motion vector difference information, the coded block flag, and the transform coefficient level to the decoding apparatus 200.

The current picture reference mode may mean a prediction mode using a pre-reconstructed region in the current picture to which the current block belongs. At this time, a vector may be defined to specify the pre-restored region. Whether the current block is coded in the current picture reference mode can be coded using the reference picture index of the current block. A flag or index indicating whether the current block is a block encoded in the current picture reference mode may be signaled or may be inferred through a reference picture index of the current block. When the current block is coded in the current picture reference mode, the current picture may be added at a fixed position or an arbitrary position within the reference picture list for the current block. The fixed position may be, for example, a position where the reference image index is 0 or the last position. When the current picture is added to an arbitrary position within the reference video list, a separate reference video index indicating the arbitrary position may be signaled.

Based on the above, the video encoding/decoding method according to the present invention will be described in detail.

5 is a flowchart illustrating an image encoding method according to an embodiment of the present invention, and FIG. 6 is a flowchart illustrating an image decoding method according to an embodiment of the present invention.

Referring to FIG. 5 , the encoding apparatus may derive a motion vector candidate (S501) and generate a motion vector candidate list based on the derived motion vector candidate (S502). When the motion vector candidate list is generated, a motion vector may be determined using the generated motion vector candidate list (S503), and motion compensation may be performed using the motion vector (S504). After that, the encoding device may entropy-encode information about motion compensation (S505).

Referring to FIG. 6 , the decoding device may entropy-decode information about motion compensation received from the encoding device (S601) and derive a motion vector candidate (S602). Then, the decoding apparatus may generate a motion vector candidate list based on the derived motion vector candidate (S603), and determine a motion vector using the generated motion vector candidate list (S604). Thereafter, the decoding apparatus may perform motion compensation using the motion vector (S605).

7 is a flowchart illustrating a video encoding method according to another embodiment of the present invention, and FIG. 8 is a flowchart illustrating a video decoding method according to another embodiment of the present invention.

Referring to FIG. 7 , the encoding device may derive a merge candidate (S701) and generate a merge candidate list based on the derived merge candidate. When the merge candidate list is generated, motion information may be determined using the generated merge candidate list (S702), and motion compensation of the current block may be performed using the determined motion information (S703). After that, the encoding device may entropy-encode information about motion compensation (S704).

Referring to FIG. 8 , the decoding device may entropy-decode information about motion compensation received from the encoding device (S801), derive a merge candidate (S802), and generate a merge candidate list based on the derived merge candidate. . When the merge candidate list is generated, motion information of the current block may be determined using the generated merge candidate list (S803). Thereafter, the decoding apparatus may perform motion compensation using the motion information (S804).

Here, FIGS. 5 and 6 may be examples to which the AMVP mode described in FIG. 4 is applied, and FIGS. 7 and 8 may be examples to which the merge mode described in FIG. 4 is applied.

Hereinafter, each step shown in FIGS. 5 and 6 will be described, and then each step shown in FIGS. 7 and 8 will be described. However, descriptions of the motion compensation steps (S504, S605, S703, and S804) and the entropy encoding/decoding steps (S505, S601, S704, and S801) are integrated and described.

Hereinafter, each step shown in FIGS. 5 and 6 will be described in detail.

First, the step of deriving motion vector candidates will be described in detail (S501 and S602).

The motion vector candidate for the current block may include at least one of a spatial motion vector candidate and a temporal motion vector candidate.

A spatial motion vector of the current block may be derived from reconstruction blocks adjacent to the current block. For example, a motion vector of a reconstruction block adjacent to the current block may be determined as a spatial motion vector candidate for the current block.

9 is a diagram for explaining an example of deriving a spatial motion vector candidate of a current block.

Referring to FIG. 9 , a spatial motion vector candidate of a current block may be derived from neighboring blocks adjacent to the current block (X). Here, the neighboring blocks adjacent to the current block include a block adjacent to the top of the current block (B1), a block adjacent to the left side of the current block (A1), a block adjacent to the upper right corner of the current block (B0), and an upper left corner of the current block. It may include at least one of a block B2 adjacent to the corner and a block A0 adjacent to the lower left corner of the current block. Meanwhile, neighboring blocks adjacent to the current block may have a square shape or a non-square shape. When a motion vector exists in a neighboring block adjacent to the current block, the motion vector of the neighboring block may be determined as a spatial motion vector candidate of the current block. Whether the motion vector of the neighboring block exists or whether the motion vector of the neighboring block is available as a spatial motion vector candidate of the current block is based on whether the neighboring block exists or whether the neighboring block has been coded through inter prediction. can be judged as At this time, whether the motion vector of the neighboring block exists or whether the motion vector of the neighboring block is available as a spatial motion vector candidate of the current block may be determined according to a predetermined priority order. For example, in the example shown in FIG. 9 , availability of motion vectors may be determined in the order of blocks at locations A0, A1, B0, B1, and B2.

When the reference image of the current block and the reference image of the neighboring block having a motion vector are different, a scaling motion vector of the neighboring block may be determined as a spatial motion vector candidate of the current block. Here, scaling may be performed based on at least one of a distance between the current image and a reference image referred to by the current block and a distance between the current image and reference images referred to by neighboring blocks. For example, the spatial motion vector candidate of the current block is derived by scaling the motion vector of the neighboring block according to the ratio of the distance between the current picture and the reference picture referenced by the current block and the distance between the current picture and the reference picture referenced by the neighboring block. It can be.

Meanwhile, when the reference picture index of the current block is different from the reference picture index of the neighboring block having the motion vector, a scaling motion vector of the neighboring block may be determined as a spatial motion vector candidate of the current block. Even in this case, scaling may be performed based on at least one of a distance between the current image and a reference image referred to by the current block and a distance between the current image and reference images referred to by neighboring blocks.

Regarding scaling, a motion vector of a neighboring block may be scaled based on a reference image indicated by a reference image index having a predefined value and determined as a spatial motion vector candidate. In this case, the predefined value may be a positive integer including 0. For example, according to the ratio of the distance between the current image and the reference image of the current block indicated by the reference image index having a predefined value, and the distance between the current image and the reference image of the neighboring block having a predefined value, a neighboring block By scaling the motion vector, a spatial motion vector candidate of the current block can be derived.

Also, a spatial motion vector candidate of the current block may be derived based on at least one or more of the coding parameters of the current block.

A temporal motion vector candidate of the current block may be derived from a reconstructed block included in a co-located picture of the current picture. Here, the corresponding position image is an image that has been encoded/decoded before the current image, and may be an image having a temporal order different from that of the current image.

10 is a diagram for explaining an example of deriving a temporal motion vector candidate of a current block.

Referring to FIG. 10 , in a collocated picture of a current image, a block including an upper position of a block corresponding to a position spatially identical to the current block X or a position spatially identical to the current block X A temporal motion vector candidate of the current block may be derived from the block including the internal position of the block corresponding to . Here, the temporal motion vector candidate may mean a motion vector of a corresponding position block. For example, the temporal motion vector candidate of the current block (X) is a block (H) adjacent to the lower left corner of the block (C) corresponding to the same spatial position as the current block or a block (C3) including the center point of the block C. can be derived from A block H or a block C3 used to derive a temporal motion vector candidate of the current block may be referred to as a 'collocated block'.

In addition, at least one of a temporal motion vector candidate, a corresponding location image, a corresponding location block, a prediction list utilization flag, and a reference image index may be derived based on at least one of the encoding parameters.

If the distance between the current image including the current block and the reference image of the current block is different from the distance between the corresponding location image including the corresponding location block and the reference image of the corresponding location block, the temporal motion vector candidate of the current block is It can be obtained by scaling the motion vector of the block. Here, scaling may be performed based on at least one of a distance between a current image and a reference image referred to by the current block and a distance between a corresponding location image and a reference image referred to by the corresponding location block. For example, by scaling the motion vector of the corresponding location block according to the ratio of the distance between the current image and the reference image referred to by the current block and the distance between the corresponding location image and the reference image referred to by the corresponding location block, the temporal motion vector of the current block is scaled. Candidates can be derived.

Next, a step of generating a motion vector candidate list based on the derived motion vector candidates will be described (S502 and S503).

Generating the motion vector candidate list may include adding or removing a motion vector candidate from the motion vector candidate list and adding a combined motion vector candidate to the motion vector candidate list.

Starting from the step of adding or removing the derived motion vector candidates to the motion vector candidate list, the encoding device and the decoding device may add the derived motion vector candidates to the motion vector candidate list in the order of motion vector candidate derivation.

It is assumed that the motion vector candidate list mvpListLX means motion vector candidate lists corresponding to the reference picture lists L0, L1, L2 and L3. For example, a motion vector candidate list corresponding to L0 in the reference picture list may be called mvpListL0.

A motion vector having a predetermined value other than the spatial motion vector candidate and the temporal motion vector candidate may be added to the motion vector candidate list. For example, when the number of motion vector candidates included in the motion vector list is smaller than the maximum number of motion vector candidates, a motion vector having a value of 0 may be added to the motion vector candidate list.

Next, a step of adding the combined motion vector candidate to the motion vector candidate list will be described.

When the number of motion vector candidates included in the motion vector candidate list is smaller than the maximum number of motion vector candidates, a motion vector combined using at least one of the motion vector candidates included in the motion vector candidate list is added to the motion vector candidate list. can do. For example, a combined motion vector candidate is generated using at least one of a spatial motion vector candidate, a temporal motion vector candidate, and a zero motion vector candidate included in the motion vector candidate list, and the generated combined motion vector candidate is moved. Can be included in vector candidate list.

Alternatively, a combined motion vector candidate may be generated based on at least one or more coding parameters, or the combined motion vector candidate may be added to a motion vector candidate list based on at least one or more coding parameters.

Next, a step of determining a predicted motion vector from the motion vector candidate list will be described (S503 and S604).

Among the motion vector candidates included in the motion vector candidate list, a motion vector candidate indicated by a motion vector candidate index may be determined as a predicted motion vector for the current block.

The encoding device may calculate a motion vector difference value by calculating a difference between the motion vector and the predicted motion vector. The decoding apparatus may calculate a motion vector by adding the predicted motion vector and the motion vector difference.

Meanwhile, the motion compensation steps of FIGS. 5 and 6 (S504 and S605) and the entropy encoding/decoding of motion compensation information (S505 and S601) are the motion compensation steps (S703 and S703) of FIGS. 7 and 8. , S804) and entropy encoding/decoding steps (S704, S801) to be described later.

Hereinafter, each step shown in FIGS. 7 and 8 will be described in detail.

First, the step of deriving a merge candidate will be described in detail (S701 and 802).

A merge candidate for the current block may include at least one of a spatial merge candidate, a temporal merge candidate, and an additional merge candidate. Here, deriving a spatial merge candidate may mean deriving a spatial merge candidate and adding the spatial merge candidate to the merge candidate list.

Referring to FIG. 9 , spatial merge candidates of the current block may be derived from neighboring blocks adjacent to the current block (X). Neighboring blocks adjacent to the current block are: the block adjacent to the top of the current block (B1), the block adjacent to the left side of the current block (A1), the block adjacent to the upper right corner of the current block (B0), and the upper left corner of the current block It may include at least one of the adjacent block B2 and the block A0 adjacent to the lower left corner of the current block.

In order to derive a spatial merge candidate of the current block, it may be determined whether neighboring blocks adjacent to the current block can be used to derive a spatial merge candidate of the current block. In this case, whether neighboring blocks adjacent to the current block can be used for deriving a spatial merge candidate of the current block may be determined according to a predetermined priority order. For example, in the example shown in FIG. 9 , spatial merge candidate derivation availability may be determined in the order of blocks of locations A1, B1, B0, A0, and B2. Spatial merge candidates determined based on the availability determination order may be sequentially added to the merge candidate list of the current block.

11 is a diagram for explaining an example in which a spatial merge candidate is added to a merge candidate list.

Referring to FIG. 11 , when four spatial merge candidates are derived from neighboring blocks at locations A1, B0, A0, and B2, the derived spatial merge candidates may be sequentially added to the merge candidate list.

In addition, the spatial merge candidate may be derived based on at least one of the coding parameters.

Here, the motion information of the spatial merge candidate may include three or more pieces of motion information such as L2 and L3 as well as motion information of L0 and L1. Here, the reference image list may include at least one of L0, L1, L2, and L3.

Next, a method of deriving a temporal merge candidate of the current block will be described.

A temporal merge candidate of the current block may be derived from a reconstructed block included in a co-located picture of the current picture. Here, the corresponding position image is an image that has been encoded/decoded before the current image, and may be an image having a temporal order different from that of the current image.

Deriving a temporal merge candidate may mean deriving a temporal merge candidate and adding it to the merge candidate list.

Referring to FIG. 10 , in a collocated picture of a current image, a block including an upper position of a block corresponding to a position spatially identical to the current block X or a position spatially identical to the current block X A temporal merge candidate of the current block may be derived from the block including the internal position of the block corresponding to . Here, the temporal merge candidate may mean motion information of a corresponding location block. For example, the temporal merge candidate of the current block (X) is from a block (H) adjacent to the lower left corner of the block (C) corresponding to the same spatial position as the current block or a block (C3) including the center point of the block C. can be induced. A block H or a block C3 used to derive a temporal merge candidate of the current block may be referred to as a 'collocated block'.

When a temporal merge candidate of the current block can be derived from block H including a location outside block C, block H may be set as a block corresponding to the current block. In this case, the temporal merge candidate of the current block may be derived based on the motion information of block H. On the other hand, when a temporal merge candidate of the current block cannot be derived from block H, block C3 including an internal location of block C may be set as a block corresponding to the current block. In this case, a temporal merge candidate of the current block may be derived based on motion information of block C3. If the temporal merge of the current block cannot be derived from block H and block C3 (eg, block H and block C3 are both intra-encoded), a temporal merge candidate for the current block is not derived or the block It may be derived from a block in a different location from H and block C3.

As another example, the temporal merge candidate of the current block may be derived from a plurality of blocks in the corresponding location image. For example, a plurality of temporal merge candidates for the current block may be derived from block H and block C3.

12 is a diagram for explaining an example in which a temporal merge candidate is added to a merge candidate list.

Referring to FIG. 12 , when one temporal merge candidate is derived from the corresponding position block of the H1 position, the derived temporal merge candidate may be added to the merge candidate list.

If the distance between the current image including the current block and the reference image of the current block is different from the distance between the corresponding location image including the corresponding location block and the reference image of the corresponding location block, the motion vector of the temporal merge candidate of the current block is It can be obtained by scaling the motion vector of the corresponding position block. Here, scaling may be performed based on at least one of a distance between a current image and a reference image referred to by the current block and a distance between a corresponding location image and a reference image referred to by the corresponding location block. For example, a temporal merge candidate of the current block is performed by scaling the motion vector of the corresponding location block according to the ratio of the distance between the current image and the reference image referred to by the current block and the distance between the corresponding location image and the reference image referred to by the corresponding location block. A motion vector of can be derived.

In addition, at least one of a temporal merge candidate, a corresponding position image, a corresponding position block, a prediction list utilization flag, and a reference image index may be derived based on at least one of the coding parameters of the current block, the neighboring block, or the corresponding position block.

After deriving at least one of the spatial merge candidates and the temporal merge candidates, the merge candidate list may be generated by adding them to the merge candidate list in the order of the derived merge candidates.

Next, a method of deriving an additional merge candidate of the current block will be described.

The additional merge candidate means at least one of a modified spatial merge candidate, a modified temporal merge candidate, a combined merge candidate, and a merge candidate having a predetermined motion information value. can do. Here, deriving additional merge candidates may mean deriving additional merge candidates and adding them to the merge candidate list.

The changed spatial merge candidate may refer to a merge candidate obtained by changing at least one of motion information of the derived spatial merge candidate.

The changed temporal merge candidate may refer to a merge candidate obtained by changing at least one of motion information of the derived temporal merge candidate.

The combined merge candidate is at least one of a spatial merge candidate, a temporal merge candidate, a modified spatial merge candidate, a modified temporal merge candidate, a combined merge candidate, and motion information of merge candidates having a predetermined motion information value existing in the merge candidate list. It may mean a merge candidate derived by combining motion information.

Alternatively, the combined merge candidate is a spatial merge candidate derived from a block that does not exist in the merge candidate list but can derive at least one or more of a spatial merge candidate and a temporal merge candidate, and a modified temporal merge candidate generated based on the spatial merge candidate and the derived temporal merge candidate. It may refer to a merge candidate derived by combining at least one motion information among a spatial merge candidate, a modified temporal merge candidate, a combined merge candidate, and a merge candidate having a predetermined motion information value.

Alternatively, a combined merge candidate may be derived using motion information entropy-decoded from a bitstream in a decoder. In this case, the motion information used to derive the merge candidate combined by the encoder may be entropy-encoded into the bitstream.

The combined merge candidate may refer to a combined bi-predictive merge candidate. The combined bi-prediction merge candidate is a merge candidate using bi-prediction and may mean a merge candidate having L0 motion information and L1 motion information.

A merge candidate having a predetermined motion information value may mean a zero merge candidate having a motion vector of (0, 0). Meanwhile, a merge candidate having a predetermined motion information value may be preset to use the same value in an encoding device and a decoding device.

At least one of a modified spatial merge candidate, a modified temporal merge candidate, a combined merge candidate, and a merge candidate having a predetermined motion information value is derived based on at least one of the coding parameters of the current block, the neighboring block, or the corresponding block, or can create In addition, at least one of a modified spatial merge candidate, a modified temporal merge candidate, a combined merge candidate, and a merge candidate having a predetermined motion information value is selected based on at least one or more of coding parameters of a current block, a neighboring block, or a corresponding position block. It can be added to the merge candidate list.

Meanwhile, the size of the merge candidate list may be determined based on encoding parameters of a current block, a neighboring block, or a corresponding block, and the size may be changed based on the encoding parameters.

Next, the step of determining the motion information of the current block using the generated merge candidate list will be described in detail (S702 and S803).

The encoder may determine a merge candidate used for motion compensation among merge candidates in the merge candidate list through motion estimation, and encode a merge candidate index (merge_idx) indicating the determined merge candidate in a bitstream.

Meanwhile, the encoder may determine motion information of the current block by selecting a merge candidate from the merge candidate list based on the above-described merge candidate index to generate a prediction block. Here, a prediction block of the current block may be generated by performing motion compensation based on the determined motion information.

The decoder may decode a merge candidate index in the bitstream to determine a merge candidate in the merge candidate list indicated by the merge candidate index. The determined merge candidate may be determined using motion information of the current block. The determined motion information is used for motion compensation of the current block. In this case, motion compensation may have the same meaning as inter prediction.

Next, steps for performing motion compensation using motion vectors or motion information will be described (S504, S605, S703, S804).

The encoding device and the decoding device may calculate a motion vector using a predicted motion vector and a motion vector difference value. When the motion vector is calculated, inter-picture prediction or motion compensation may be performed using the calculated motion vector (S504 and S605).

Meanwhile, the encoding device and the decoding device may perform inter-picture prediction or motion compensation using the determined motion information (S703 and S804). Here, the current block may have motion information of the determined merge candidate.

The current block may have a minimum of 1 to a maximum of N motion vectors according to prediction directions. A final prediction block of a current block may be derived by generating a minimum of 1 to a maximum of N prediction blocks using a motion vector.

For example, when the current block has one motion vector, a prediction block generated using the motion vector (or motion information) may be determined as the final prediction block of the current block.

On the other hand, when the current block has a plurality of motion vectors (or motion information), a plurality of prediction blocks are generated using the plurality of motion vectors (or motion information), and based on a weighted sum of the plurality of prediction blocks, the current A final prediction block of the block may be determined. Reference images including each of a plurality of prediction blocks indicated by a plurality of motion vectors (or motion information) may be included in different reference image lists or in the same reference image list.

For example, a plurality of prediction blocks are generated based on at least one of a spatial motion vector candidate, a temporal motion vector candidate, a motion vector having a predetermined value, or a combined motion vector candidate, and based on a weighted sum of the plurality of prediction blocks , it is possible to determine the final prediction block of the current block.

As another example, a plurality of prediction blocks may be generated based on motion vector candidates indicated by preset motion vector candidate indices, and a final prediction block of the current block may be determined based on a weighted sum of the plurality of prediction blocks. Also, a plurality of prediction blocks may be generated based on motion vector candidates existing in a preset motion vector candidate index range, and a final prediction block of the current block may be determined based on a weighted sum of the plurality of prediction blocks.

The weight applied to each prediction block may have an equal value of 1/N (where N is the number of generated prediction blocks). For example, when 2 prediction blocks are generated, the weight applied to each prediction block is 1/2, and when 3 prediction blocks are generated, the weight applied to each prediction block is 1/3, and 4 prediction blocks are generated. When a block is generated, a weight applied to each prediction block may be 1/4. Alternatively, a final prediction block of the current block may be determined by assigning a different weight to each prediction block.

The weight does not have to have a fixed value for each prediction block, and may have a variable value for each prediction block. In this case, the weights applied to each prediction block may be the same or different. For example, when two prediction blocks are generated, the weight applied to the two prediction blocks is not only (1/2, 1/2), but also (1/3, 2/3), (1/4, 3 /4), (2/5, 3/5), (3/8, 5/8) may be a variable value for each block. Meanwhile, the weight may be a positive real number value or a negative real number value. For example, negative real values such as (-1/2, 3/2), (-1/3, 4/3), and (-1/4, 5/4) may be included.

Meanwhile, in order to apply a variable weight, one or more weight information for the current block may be signaled through a bitstream. Weight information may be signaled for each prediction block or for each reference picture. It is also possible for a plurality of prediction blocks to share one weight information.

The encoding apparatus and the decoding apparatus may determine whether to use the predicted motion vector (or motion information) based on the prediction block list utilization flag. For example, when the prediction block list utilization flag for each reference image list indicates the first value of 1, the encoding device and the decoding device can use the predicted motion vector of the current block to perform inter-prediction or motion compensation. and when the second value of 0 is indicated, it may indicate that the encoding device and the decoding device do not perform inter-prediction or motion compensation using the predicted motion vector of the current block. Meanwhile, the first value of the prediction block list utilization flag may be set to 0 and the second value may be set to 1. Equations 1 to 3 below are examples of generating the final prediction block of the current block when the inter prediction indicators of the current block are PRED_BI, PRED_TRI, and PRED_QUAD, and the prediction direction for each reference picture list is unidirectional. indicates

In Equations 1 to 3, P_BI, P_TRI, and P_QUAD denote the final prediction block of the current block, and LX (X=0, 1, 2, 3) may denote a reference image list. WF_LX may represent a weight value of a prediction block generated using LX, and OFFSET_LX may represent an offset value for a prediction block generated using LX. P_LX means a prediction block generated using a motion vector (or motion information) for LX of the current block. RF means a rounding factor and can be set to 0, a positive number, or a negative number. The LX reference image list includes a long-term reference image, a reference image without performing a deblocking filter, a reference image without performing a sample adaptive offset, and an adaptive loop filter (adaptive loop filter). loop filter), reference image with only deblocking filter and adaptive offset, reference image with only deblocking filter and adaptive loop filter, reference image with sample adaptive offset and adaptive loop filter only It may include at least one of reference images on which all of the image, deblocking filter, sample adaptive offset, and adaptive loop filter are performed. In this case, the LX reference picture list may be at least one of an L2 reference picture list and an L3 reference picture list.

Even when prediction directions for a predetermined reference image list are multi-directional, a final prediction block for a current block may be obtained based on a weighted sum of prediction blocks. In this case, weights applied to prediction blocks derived from the same reference image list may have the same value or different values.

At least one of a weight (WF_LX) and an offset (OFFSET_LX) for a plurality of prediction blocks may be an encoding parameter for entropy encoding/decoding. As another example, the weight and offset may be derived from encoded/decoded neighboring blocks around the current block. Here, neighboring blocks adjacent to the current block may include at least one of a block used to derive a spatial motion vector candidate of the current block and a block used to derive a temporal motion vector candidate of the current block.

As another example, the weight and offset may be determined based on the display order (POC) of the current image and each reference image. In this case, the weight or offset may be set to a smaller value as the distance between the current image and the reference image increases, and the weight or offset may be set to a larger value as the distance between the current image and the reference image decreases. For example, when the POC difference between the current image and the L0 reference image is 2, the weight value applied to the prediction block generated with reference to the L0 reference image is set to 1/3, whereas the POC difference between the current image and the L0 reference image is set. When is 1, a weight value applied to a prediction block generated with reference to the L0 reference picture may be set to 2/3. As exemplified above, the weight or offset value may have an inverse relationship with the display order difference between the current image and the reference image. As another example, the weight or offset value may have a proportional relationship with a difference in display order between the current image and the reference image.

As another example, entropy encoding/decoding may be performed on at least one of weights and offsets based on at least one of encoding parameters. Also, a weighted sum of prediction blocks may be calculated based on at least one of the coding parameters.

A weighted sum of a plurality of prediction blocks may be applied only to some regions within a prediction block. Here, the partial region may be a region corresponding to a boundary within a prediction block. As above, in order to apply weighted sum only to some regions, weighted sum may be performed in units of sub-blocks of prediction blocks.

Inter-prediction or motion compensation may be performed using the same prediction block or the same final prediction block in lower blocks having a smaller block size within a block having a block size indicated by the region information.

In addition, inter-prediction or motion compensation may be performed using the same prediction block or the same final prediction block in sub-blocks having a deeper block depth within a block having a block depth indicated by region information.

In addition, when calculating the weighted sum of prediction blocks using motion vector prediction, the weighted sum can be calculated using at least one motion vector candidate existing in the motion vector candidate list and used as the final prediction block of the current block.

For example, prediction blocks may be generated using only spatial motion vector candidates, a weighted sum of the prediction blocks may be calculated, and the calculated weighted sum may be used as a final prediction block of the current block.

For example, prediction blocks may be generated from spatial motion vector candidates and temporal motion vector candidates, a weighted sum of the prediction blocks may be calculated, and the calculated weighted sum may be used as a final prediction block of the current block.

For example, prediction blocks may be generated using only the combined motion vector candidates, a weighted sum of the prediction blocks may be calculated, and the calculated weighted sum may be used as a final prediction block of the current block.

For example, prediction blocks may be generated only with motion vector candidates having specific motion vector candidate indices, a weighted sum of the prediction blocks may be calculated, and the calculated weighted sum may be used as the final prediction block of the current block.

For example, prediction blocks may be generated only with motion vector candidates existing within a specific motion vector candidate index range, a weighted sum of the prediction blocks may be calculated, and the calculated weighted sum may be used as the final prediction block of the current block.

In addition, when calculating the weighted sum of prediction blocks using the merge mode, the weighted sum can be calculated using at least one merge candidate existing in the merge candidate list and used as the final prediction block of the current block.

For example, prediction blocks may be generated using only spatial merge candidates, a weighted sum of the prediction blocks may be calculated, and the calculated weighted sum may be used as a final prediction block of the current block.

For example, prediction blocks may be generated using spatial merge candidates and temporal merge candidates, a weighted sum of the prediction blocks may be calculated, and the calculated weighted sum may be used as a final prediction block of the current block.

For example, prediction blocks may be generated using only combined merge candidates, a weighted sum of the prediction blocks may be calculated, and the calculated weighted sum may be used as a final prediction block of the current block.

For example, prediction blocks may be generated only with merge candidates having specific merge candidate indices, a weighted sum of the prediction blocks may be calculated, and the calculated weighted sum may be used as the final prediction block of the current block.

For example, prediction blocks may be generated only with merge candidates existing within a specific merge candidate index range, a weighted sum of the prediction blocks may be calculated, and the calculated weighted sum may be used as the final prediction block of the current block.

The encoder and decoder may perform motion compensation using the motion vector/information of the current block. In this case, a final prediction block as a result of motion compensation may be generated using at least one or more prediction blocks. Here, the current block may mean at least one of a current coding block and a current prediction block.

A final prediction block may be generated by performing overlapped block motion compensation on a region corresponding to a boundary within the current block.

An area corresponding to a boundary within the current block may be an area within the current block adjacent to the boundary of neighboring blocks of the current block. Here, the region corresponding to the boundary within the current block is among the upper boundary region, the left boundary region, the lower boundary region, the right boundary region, the upper right corner region, the lower right corner region, the upper left corner region, and the lower left corner region in the current block. It may contain at least one or more. Also, a region corresponding to a boundary within the current block may be a region corresponding to a part within the prediction block of the current block.

The overlapped block motion compensation performs motion compensation by calculating a weighted sum of prediction blocks generated using a prediction block area corresponding to a boundary within the current block and motion information of encoded/decoded blocks adjacent to the current block. can mean

The weighted sum may be performed in units of sub-blocks after dividing the current block into a plurality of sub-blocks. That is, motion compensation may be performed using motion information of an encoded/decoded block adjacent to the current block in units of sub-blocks. In this case, a sub-block may mean a sub-block.

In addition, in the weighted sum calculation, a first prediction block generated in units of sub-blocks using motion information of the current block and a second prediction block generated using motion information of neighboring sub-blocks spatially adjacent to the current block may be used. . At this time, using motion information may mean inducing motion information. Also, the first prediction block may refer to a prediction block generated using motion information of a sub-block to be encoded/decoded within the current block. Also, here, the second prediction block may refer to a prediction block generated using motion information of adjacent sub-blocks spatially adjacent to a sub-block to be encoded/decoded within the current block.

A final prediction block may be generated using a weighted sum of the first prediction block and the second prediction block. That is, the overlapped block motion compensation may generate a final prediction block by using motion information of other blocks in addition to motion information of the current block.

In addition, Advanced Motion Vector Prediction (AMVP), merge mode, affine motion compensation mode, decoder motion vector derivation mode, adaptive motion vector resolution mode, area illumination compensation mode, bi-directional optical flow In case of corresponding to at least one of the modes, overlapping block motion compensation may be performed for each sub-block after dividing the current prediction block into sub-blocks.

Here, in the case of the merge mode, block motion compensation superimposed on at least one of an Advanced Temporal Motion Vector Predictor (ATMVP) candidate and a Spatial-Temporal Motion Vector Predictor (STMVP) candidate. can be performed.

A detailed description of overlapped block motion compensation will be described later based on FIGS. 13 to 24 .

Next, a process of entropy encoding/decoding information related to motion compensation will be described in detail (S505, S601, S704, S801).

The encoding device may entropy-encode motion compensation information through a bitstream, and the decoding device may entropy-decode motion compensation information included in the bitstream. Here, information on motion compensation that is entropy encoded/decoded includes an inter prediction indicator (inter_pred_idc), reference picture indices (ref_idx_l0, ref_idx_l1, ref_idx_l2, ref_idx_l3), motion vector candidate indices (mvp_l0_idx, mvp_l1_idx, mvp_l2_idx , mvp_l3_idx), motion vector difference, skip mode use information (cu_skip_flag), merge mode use information (merge_flag), merge index information (merge_index), weight values (wf_l0, wf_l1, wf_l2, wf_l3) and It may include at least one of offset values (offset_l0, offset_l1, offset_l2, offset_l3).

The inter prediction indicator may mean at least one of an inter prediction direction of the current block or the number of prediction directions when encoding/decoding is performed by inter prediction of the current block. For example, the inter-prediction indicator may indicate unidirectional prediction or multidirectional prediction such as bidirectional prediction, three-way prediction, or four-way prediction. The inter-prediction indicator may indicate the number of reference images used when the current block generates a prediction block. Alternatively, one reference image may be used for prediction of a plurality of directions. In this case, N (N>M) direction prediction may be performed using M reference images. The inter-prediction indicator may mean the number of prediction blocks used when performing inter-prediction or motion compensation for a current block.

The reference image indicator may indicate unidirectional (PRED_LX), bidirectional (PRED_BI), three-directional (PRED_TRI), four-directional (PRED_QUAD) or more directions according to the number of prediction directions of the current block.

A prediction list utilization flag indicates whether a prediction block is generated using a corresponding reference image list.

For example, when the prediction list utilization flag indicates a first value of 1, it indicates that a prediction block can be generated using the corresponding reference image list, and when indicating a second value of 0, using the corresponding reference image list It may indicate not generating a prediction block. Here, the first value of the prediction list utilization flag may be set to 0 and the second value may be set to 1.

That is, when the prediction list utilization flag indicates a first value, a prediction block of the current block may be generated using motion information corresponding to the corresponding reference image list.

The reference image index may specify a reference image referred to by a current block in each reference image list. For each reference picture list, one or more reference picture indices may be entropy encoded/decoded. The current block may perform motion compensation using one or more reference picture indices.

The motion vector candidate index represents a motion vector candidate for a current block in a motion vector candidate list generated for each reference picture list or for each reference picture index. At least one motion vector candidate index for each motion vector candidate list may be entropy encoded/decoded. The current block may perform motion compensation using at least one motion vector candidate index.

The motion vector difference represents a difference value between a motion vector and a predicted motion vector. One or more motion vector differences may be entropy-encoded/decoded with respect to the reference picture list for the current block or the motion vector candidate list generated for each reference picture index. The current block may perform motion compensation using one or more motion vector differentials.

Skip mode usage availability information (cu_skip_flag) may indicate use of skip mode when it has a first value of 1, and may not indicate use of skip mode when it has a second value of 0. Motion compensation of the current block may be performed by using the skip mode based on information on whether the skip mode is used.

Merge mode use availability information (merge_flag) may indicate use of merge mode when it has a first value of 1, and may not indicate use of merge mode when it has a second value of 0. Motion compensation of the current block may be performed using merge mode based on information on whether merge mode is used or not.

The merge index information (merge_index) may refer to information indicating a merge candidate in a merge candidate list.

Also, merge index information may refer to information about a merge index.

In addition, the merge index information may indicate a block from which a merge candidate is derived among blocks reconstructed that are spatially/temporally adjacent to the current block.

Also, the merge index information may indicate at least one piece of motion information of a merge candidate. For example, if the merge index information has a first value of 0, it may indicate the first merge candidate in the merge candidate list, and if it has a second value of 1, it may indicate the second merge candidate in the merge candidate list, If it has the third value of 2, it may indicate the third merge candidate in the merge candidate list. Similarly, when the values have the 4th to Nth values, merge candidates corresponding to the values may be indicated according to the order in the merge candidate list. Here, N may mean a positive integer including 0.

Motion compensation of the current block may be performed using merge mode based on merge mode index information.

When two or more prediction blocks are generated during motion compensation for the current block, a final prediction block for the current block may be generated through a weighted sum of each prediction block. During the weighted sum operation, at least one of a weight and an offset may be applied to each prediction block. A weighting factor used in a weighted sum operation, such as a weighting factor or an offset, includes a reference image list, a reference image, a motion vector candidate index, a motion vector difference, a motion vector, skip mode use information, merge mode Entropy encoding/decoding may be performed as much as or more than at least one of the usage information and the merge index information. In addition, the weighted sum factor of each prediction block may be entropy encoded/decoded based on an inter prediction indicator. Here, the weighted sum factor may include at least one of a weight and an offset.

Information on motion compensation may be entropy-encoded/decoded on a block-by-block basis or entropy-encoded/decoded at a higher level. For example, motion compensation information is entropy encoded/decoded in units of blocks such as CTU, CU, or PU, or a video parameter set, a sequence parameter set, or a picture parameter set. ), entropy encoding/decoding may be performed at a higher level such as an Adaptation Parameter Set or a Slice Header.

Information on motion compensation may be entropy-encoded/decoded based on a difference value between information on motion compensation and a predicted value of information on motion compensation.

Instead of entropy encoding/decoding information on motion compensation of the current block, information on motion compensation of blocks encoded/decoded around the current block may be used as information on motion compensation of the current block.

In addition, at least one or more of the motion compensation-related information may be derived based on at least one or more of the coding parameters.

In addition, at least one or more of the motion compensation information may be entropy-decoded from a bitstream based on at least one or more encoding parameters. At least one or more of the motion compensation information may be entropy-encoded into a bitstream based on at least one or more encoding parameters.

Motion compensation information includes a motion vector, a motion vector candidate, a motion vector candidate index, a motion vector difference value, a motion vector prediction value, skip mode use information (skip_flag), merge mode use information (merge_flag), merge index information (merge_index) ), motion vector resolution information, overlapped block motion compensation information, local illumination compensation information, affine motion compensation information, decoder motion vector It may further include at least one of decoder-side motion vector derivation information and bi-directional optical flow information. Here, decoder motion vector derivation may mean pattern matched motion vector derivation.

The motion vector resolution information may be information indicating whether a specific resolution is used for at least one of the motion vector and the motion vector difference value. Here, resolution may mean precision. In addition, the specific resolution is 16-pixel (16-pel) unit, 8-pixel (8-pel) unit, 4-pixel (4-pel) unit, integer-pixel unit, 1/2-pixel unit (1/2-pel) unit, 1/4-pixel (1/4-pel) unit, 1/8-pixel (1/8-pel) unit, 1/16-pixel (1/16-pel) unit , 1/32-pixel (1/32-pel) unit, and 1/64-pixel (1/64-pel) unit.

The overlapped block motion compensation information may be information indicating whether a weighted sum of prediction blocks of the current block is calculated by additionally using motion vectors of neighboring blocks spatially adjacent to the current block during motion compensation of the current block.

Area illumination compensation information may be information indicating whether at least one of a weight value and an offset value is applied when generating a prediction block of a current block. Here, at least one of the weight value and the offset value may be a value calculated based on the reference block.

The affine motion compensation information may be information indicating whether an affine motion model is used when motion compensation for the current block is performed. Here, the affine motion model may be a model that divides one block into multiple sub-blocks using a plurality of parameters and calculates motion vectors of the divided sub-blocks using representative motion vectors.

The decoder motion vector derivation information may be information indicating whether the decoder derives and uses a motion vector necessary for motion compensation. Based on the decoder motion vector derivation information, motion vector information may not be entropy encoded/decoded. And, when the decoder motion vector derivation information indicates that the decoder derives and uses the motion vector, information on the merge mode may be entropy encoded/decoded. That is, the decoder motion vector derivation information may indicate whether the decoder uses merge mode.

The bidirectional optical flow information may be information indicating whether motion compensation is performed by calibrating a motion vector in units of pixels or units of sub-blocks. Based on the bidirectional optical flow information, a motion vector in units of pixels or units of sub-blocks may not be entropy-encoded/decoded. Here, the motion vector correction may be to change a motion vector value of a motion vector in units of blocks or in units of pixels or sub-blocks.

The current block may perform motion compensation using at least one piece of motion compensation information, and entropy-encode/decode at least one piece of motion compensation information.

In the case of entropy encoding/decoding information related to motion compensation, a truncated rice binarization method, a K-th order Exp_Golomb binarization method, and a restricted K-th order Exp_Golomb binarization method ) Binarization method, such as a fixed-length binarization method, a unary binarization method, or a truncated unary binarization method, may be used.

When entropy encoding/decoding information about motion compensation, information about motion compensation of neighboring blocks around the current block or area information of neighboring blocks, information about previously encoded/decoded motion compensation, or information about previously encoded/decoded motion compensation A context model may be determined using at least one of region information, information about the depth of the current block, and information about the size of the current block.

In addition, when entropy encoding/decoding information about motion compensation, information about motion compensation of neighboring blocks, information about previously encoded/decoded motion compensation, information about the depth of the current block, and information about the size of the current block Entropy encoding/decoding may be performed by using at least one of the pieces of information as a predicted value for motion compensation information of the current block.

Hereinafter, detailed descriptions related to overlapped block motion compensation will be described with reference to FIGS. 13 to 24 .

* FIG. 13 is a diagram for explaining an example in which overlapped block motion compensation is performed in sub-block units.

Referring to FIG. 13 , a hatched block is an area to which overlapped block motion compensation is applied, and may be a sub-block corresponding to a boundary within the current block or a sub-block within the current block. Also, a block marked with a thick line may be a current block.

Also, an arrow may mean that motion information of an adjacent neighboring sub-block is used for motion compensation of the current sub-block. Here, the position corresponding to the tail of the arrow may mean 1) a neighboring sub-block adjacent to the current block or 2) a neighboring sub-block within the current block adjacent to the current sub-block. Also, a position corresponding to the head of the arrow may mean a current sub-block within the current block.

In the shaded block, a weighted sum of the first prediction block and the second prediction block may be calculated. As motion information used when generating the first prediction block, motion information on a current sub-block within the current block may be used. Motion information used when generating the second prediction block may use at least one of motion information of neighboring subblocks adjacent to the current block and motion information of neighboring subblocks within the current block.

In addition, in order to improve encoding efficiency, the motion information used for generating the second prediction block is the upper block, the left block, the lower block, the right block, the upper right block, the lower right block, and the upper left block based on the position of the current lower block in the current block. It may be motion information of at least one block among the block and the lower left block. Locations of available neighboring sub-blocks may be determined according to the location of the current sub-block. For example, when the current sub-block is located at the top boundary, at least one neighboring sub-block located at the top, top right, and top left of the current sub-block may be used. When the current sub-block is located at the left boundary, at least one neighboring sub-block located at the left, top-left, and bottom-left of the current sub-block may be used.

Here, based on the location of the current sub-block, the upper block, left block, lower block, right block, upper right block, lower right block, upper left block, and lower left block are the upper peripheral subblock, the left peripheral subblock, and the lower peripheral subblock. .

Meanwhile, in order to reduce computational complexity, motion information used to generate the second prediction block may be changed according to the size of a motion vector of a neighboring subblock adjacent to the current block or a neighboring subblock within the current block.

For example, when neighboring sub-blocks are bi-directionally predicted, magnitudes of motion vectors in directions L0 and L1 may be compared and a second prediction block may be generated using only motion information in one direction having a large magnitude.

As another example, the second prediction block may be generated using only motion vectors in which the sum of the absolute values of the x component and the y component of the motion vector is greater than or equal to a predefined value among the L0 and L1 direction motion vectors of neighboring subblocks. . Here, the predefined value may be a positive integer including 0, determined by information signaled from an encoder to a decoder, or may be a value set identically to the encoder and decoder.

In addition, in order to reduce computational complexity, motion information used to generate the second prediction block may be changed according to the magnitude and direction of the motion vector of the current sub-block.

For example, if the absolute value of the x component and the absolute value of the y component of the current sub-block are compared and the absolute value of the x component is large, second prediction is performed using at least one of the motion information of the left block and the right block. blocks can be created.

As another example, after comparing the magnitudes of the absolute values of the motion vector x and y components of the current sub-block, if the absolute value of the y-component is large, second prediction using at least one of the motion information of the upper block and the lower block blocks can be created.

As another example, when the absolute value of the motion vector x component of the current sub-block is greater than or equal to a predefined value, the second prediction block may be generated using at least one of the motion information of the left block and the right block. . Here, the predefined value may be a positive integer including 0, determined by information signaled from an encoder to a decoder, or may be a value set identically to the encoder and decoder.

As another example, when the absolute value of the motion vector y component of the current lower block is greater than or equal to a predefined value, the second prediction block may be generated using at least one of the motion information of the upper block and the lower block. . Here, the predefined value may be a positive integer including 0, determined by information signaled from an encoder to a decoder, or may be a value set identically to the encoder and decoder.

Meanwhile, the size of the sub-block may have NxM, where N and M may be positive integers. N and M may be the same as or different from each other. For example, the sub-block size may be 4x4 or 8x8, and sub-block size information may be entropy-encoded/decoded in sequence units.

Also, the size of the lower block may be determined according to the size of the current block. For example, if the size of the current block is K samples or less, a 4x4 sub-block may be used, and if the size of the current block is greater than K samples, an 8x8 sub-block may be used. Here, K is a positive integer and may be, for example, 256.

Here, the information on the size of the sub-block may be entropy-encoded/decoded in at least one of a sequence unit, a picture unit, a slice unit, a tile unit, a CTU unit, a CU unit, and a PU unit. In addition, the size of the sub-block may use a size predefined in the encoder and decoder.

The sub-block may have at least one of a square shape and a rectangular shape. For example, when the current block has a square or rectangular shape, the lower block may have a square shape.

For example, when the current block has a rectangular shape, sub-blocks may have a rectangular shape.

Here, the information on the shape of the sub-block may be entropy encoded/decoded in at least one of a sequence unit, a picture unit, a slice unit, a tile unit, a CTU unit, a CU unit, and a PU unit. In addition, the form of a sub-block may use a form predefined in an encoder and a decoder.

14 is a diagram for explaining an example in which motion compensation for overlapping blocks is performed using motion information of a lower block of a corresponding block. In order to improve encoding efficiency, motion information of a corresponding-position sub-block corresponding to a spatially identical position to a current block in a corresponding-position image or reference image may be used as motion information used to generate a second prediction block.

Referring to FIG. 14 , motion information of a sub-block temporally adjacent to a current block within a corresponding location block may be used for overlapped block motion compensation of the current sub-block. Here, a position corresponding to the tail of an arrow may mean a lower block within a corresponding position block. Also, a position corresponding to the head of the arrow may mean a current sub-block within the current block.

Further, as described above, motion information of at least one of the motion information of the corresponding position sub-block in the corresponding position image, motion information of neighboring sub-blocks spatially adjacent to the current block, and neighboring sub-blocks spatially adjacent to the current sub-block within the current block. Can be used to generate the second prediction block.

15 is a diagram for explaining an example in which overlapped block motion compensation is performed using motion information of a block adjacent to a boundary region of a reference block. To improve encoding efficiency, a reference block in a reference image is identified using at least one of the motion vector of the current block and the reference image index, and motion information of neighboring blocks adjacent to the boundary of the identified reference block is generated as a second prediction block. It can be used as motion information used for Here, the neighboring block may include an encoded/decoded block adjacent to a lower block located in a lower boundary region or a right boundary region of the reference block.

Referring to FIG. 15 , motion information of a block encoded/decoded adjacent to a lower boundary region and a right boundary region of a reference block may be used for overlapped block motion compensation of a current lower block.

In addition, as described above, motion information of blocks encoded/decoded adjacent to the lower boundary region and right boundary region of the reference block, motion information of neighboring sub-blocks spatially adjacent to the current block, and spatially related to the current sub-block within the current block Motion information of at least one of adjacent neighboring sub-blocks may be used to generate the second prediction block.

Meanwhile, in order to improve encoding efficiency, motion information of at least one of merge candidates included in the merge candidate list may be used as motion information used to generate the second prediction block. Here, the merge candidate list may be a list used in a merge mode among inter prediction modes.

For example, a spatial merge candidate in the merge candidate list may be used as motion information used to generate the second prediction block.

As another example, a temporal merge candidate in the merge candidate list may be used as motion information used to generate the second prediction block.

As another example, a merge candidate combined in the merge candidate list may be used as motion information used to generate the second prediction block.

Alternatively, in order to improve coding efficiency, at least one motion vector among motion vector candidates included in the motion vector candidate list may be used as a motion vector used to generate the second prediction block. Here, the motion vector candidate list may be a list used in the AMVP mode among inter prediction modes.

For example, a spatial motion vector candidate in the motion vector candidate list may be used as motion information used to generate the second prediction block.

As another example, a temporal motion vector candidate in the motion vector candidate list may be used as motion information used to generate the second prediction block.

When at least one of the above-described merge candidate and motion vector candidate is used as motion information used to generate the second prediction block, regions to which overlapped block motion compensation is applied may be different. The area to which overlapped block motion compensation is applied is set to an area adjacent to one boundary of a block (ie, a sub-block located on a block boundary) or an area not adjacent to a block boundary (ie, a sub-block not located on a block boundary), etc. It can be.

In this case, for block motion compensation overlapped in an area not adjacent to a block boundary, at least one of a merge candidate and a motion vector candidate may be used as motion information used in the second prediction block.

For example, using motion information of a spatial merge candidate or a spatial motion vector candidate, motion compensation for overlapped blocks in a region not adjacent to a block boundary may be performed.

As another example, motion compensation for overlapped blocks in a region not adjacent to a block boundary may be performed using motion information of a temporal merge candidate or a temporal motion vector candidate.

As another example, motion compensation for blocks overlapping the lower boundary region and the right boundary region of a block may be performed using motion information of a spatial merge candidate or a spatial motion vector candidate.

As another example, motion compensation for blocks overlapping the lower boundary region and the right boundary region of a block may be performed using motion information of a temporal merge candidate or a temporal motion vector candidate.

In addition, to improve coding efficiency, motion information derived from a block at a specific position in a merge candidate list or a motion vector candidate list may be used when compensating for overlapping block motion in a specific region.

For example, when motion information derived from an upper right block based on a current block is included in the merge candidate list or the motion vector candidate list, the corresponding motion information can be used when compensating for overlapped block motion of the right boundary region of the block.

As another example, if motion information derived from the lower left block based on the current block is included in the merge candidate list or the motion vector candidate list, the corresponding motion information can be used when compensating for overlapped block motion in the lower boundary region of the blocks. .

16 is a diagram for explaining an example in which overlapped block motion compensation is performed in units of sub-block groups. In order to reduce computational complexity, sub-block-based overlapped block motion compensation may be performed in units of one or more blocks in which several sub-blocks are combined. In this case, a block unit in which several sub-blocks are combined may mean a sub-block group unit.

Referring to FIG. 16 , each segmented area in the hatched area may mean a sub-block group. Also, an arrow may indicate that motion information of an adjacent neighboring sub-block is used for motion compensation of a current sub-block group. Here, the position corresponding to the tail of the arrow may mean 1) a neighboring sub-block adjacent to the current block, 2) a neighboring sub-block group adjacent to the current block, or 3) a neighboring sub-block within the current block adjacent to the current sub-block. Also, a position corresponding to the head of the arrow may mean a current sub-block group within the current block.

In the lower block group, a weighted sum of the first prediction block and the second prediction block may be calculated. As motion information used when generating the first prediction block, motion information on a current sub-block group within the current block may be used. Here, the motion information on the current sub-block group within the current block may be any one of an average value, a median value, a minimum value, a maximum value, or a weighted sum of motion information on the sub-blocks included in the sub-block group. Further, the motion information used when generating the second prediction block includes motion information of neighboring subblocks adjacent to the current block, motion information of neighboring subblock groups adjacent to the current block, and neighboring subblocks adjacent to the current subblock within the current block. At least one of the motion information of may be used. Here, motion information of neighboring sub-block groups adjacent to the current block may be any one of an average value, a median value, a minimum value, a maximum value, or a weighted sum of motion information on sub-blocks included in the neighboring sub-block group.

Here, at least one sub-block group unit may exist in the current block, and the horizontal size of the sub-block group unit may be equal to or smaller than the horizontal size of the current sub-block. Also, the vertical size of each sub-block group may be equal to or smaller than the vertical size of the current sub-block. Also, block motion compensation may be performed overlapped with at least one of sub-blocks positioned at an upper boundary within the current block and sub-blocks positioned at a left boundary within the current block.

Meanwhile, since the blocks adjacent to the lower boundary and the right boundary of the current block are not encoded/decoded, blocks overlapping at least one of sub-blocks located on the lower boundary of the current block and sub-blocks located on the right boundary of the current block Motion compensation may not be performed. Alternatively, since the blocks adjacent to the lower boundary and the right boundary of the current block are not encoded/decoded, at least one of the subblocks located at the lower boundary within the current block and the subblocks located at the right boundary within the current block is included in the current subblock. Overlapped block motion compensation may be performed using motion information of at least one of an upper block, a left block, an upper left block, a lower left block, and an upper right block of .

In addition, when the current block is a merge mode and is at least one of an enhanced temporal motion vector prediction candidate and a spatio-temporal motion vector prediction candidate, sub-blocks positioned at a lower boundary within the current block and sub-blocks located at a right boundary within the current block Block motion compensation overlapped with at least one of the blocks may not be performed.

In addition, when the current block is in the decoder motion vector derivation mode or the affine motion compensation mode, block motion superimposed on at least one of sub-blocks located at the lower boundary within the current block and sub-blocks located at the right boundary within the current block. Compensation may not be performed.

Meanwhile, overlapped block motion compensation may be performed on at least one or more of each color component of the current block. In this case, the color component may include at least one of a luminance component and a color difference component.

In addition, overlapping block motion compensation may be performed according to an inter prediction indicator of the current block. That is, it can be performed when the current block is at least one of unidirectional prediction, bidirectional prediction, 3-way prediction, and 4-way prediction. Also, it can be performed only when the current block is unidirectional prediction. Also, it can be performed only when the current block is bidirectional prediction.

17 is a diagram for explaining an example of the number of pieces of motion information used for overlapping block motion compensation.

Motion information used to generate the second prediction block may be up to K pieces. That is, up to K second prediction blocks may be generated and used for overlapping block motion compensation. Here, K may be a positive integer including 0, and may be, for example, 1, 2, 3, or 4.

For example, when the second prediction blocks are generated using motion information of neighboring sub-blocks adjacent to the current block, up to two pieces of motion information can be derived using at least one of the upper block and the left block. In addition, when generating second prediction blocks using motion information of neighboring sub-blocks adjacent to the current sub-block within the current block, the upper block, the left block, the lower block, the right block, the upper left block, the upper right block, and the lower left block and at least one of the lower right blocks may be used to derive up to four pieces of motion information. At this time, the meaning of deriving the motion information may mean that the second prediction block is generated using the derived motion information and then used for motion compensation of overlapped blocks.

Referring to FIG. 17, in order to improve coding efficiency, motion information used to generate a second prediction block corresponding to at least one of sub-blocks located at the upper boundary of the current block and sub-blocks located at the left boundary of the current block can induce up to three. That is, motion information used to generate the second prediction block may be derived using 3-connectivity.

For example, blocks corresponding to the upper boundary area within the current block may derive motion information from at least one of a neighboring upper block, a neighboring upper left block, and a neighboring upper right block, which are neighboring lower blocks adjacent to the current block.

In addition, blocks corresponding to the left boundary area within the current block may derive motion information from at least one of a neighboring left block, a neighboring upper left block, and a neighboring lower left block, which are neighboring lower blocks adjacent to the current block.

In addition, blocks corresponding to the upper left boundary area within the current block may derive motion information from at least one of a neighboring upper block, a neighboring left block, and a neighboring upper left block, which are neighboring lower blocks adjacent to the current block.

In addition, blocks corresponding to the upper right boundary area within the current block may derive motion information from at least one of a neighboring upper block, an upper left neighboring block, and an upper right neighboring block, which are neighboring lower blocks adjacent to the current block.

Also, blocks corresponding to the lower left boundary area within the current block may derive motion information from at least one of a neighboring left block, a neighboring upper left block, and a neighboring lower left block, which are neighboring subblocks adjacent to the current block.

Meanwhile, in order to improve coding efficiency, motion information used for generation of the second prediction block is reduced to the maximum when it does not correspond to at least one of sub-blocks located at the upper boundary within the current block and sub-blocks located at the left boundary within the current block. Up to 8 can be induced. That is, motion information used to generate the second prediction block may be derived using 8-connectivity.

For example, the current sub-blocks in the current block are neighboring upper blocks, neighboring left blocks, neighboring lower blocks, neighboring right blocks, neighboring upper left blocks, neighboring lower left blocks, and neighboring subblocks adjacent to the current subblock within the current block. Motion information may be derived from at least one of a lower right block and a neighboring upper right block.

Meanwhile, motion information used to generate the second prediction block may be derived from the corresponding-position lower block in the corresponding-position image. In addition, motion information used to generate the second prediction block may be derived from an encoded/decoded block adjacent to the lower boundary region and the right boundary region of the reference block in the reference image.

In addition, in order to improve coding efficiency, the number of motion information used to generate the second prediction block may be determined according to the magnitude or direction of the motion vector.

For example, when the sum of the absolute values of the x component and the y component of the motion vector is equal to or greater than J, a maximum of L may be used as the number of motion information. Conversely, if the sum of the absolute values of the x and y components of the motion vector is smaller than J, a maximum of P may be used as the number of motion information. In this case, J, L, and P may be positive integers including 0. L and P are preferably different values, but may have the same value.

In addition, when the current block is a merge mode and is at least one of an enhanced temporal motion vector prediction candidate and a spatial-temporal motion vector prediction candidate, a maximum of K pieces of motion information may be used to generate the second prediction block. Here, K may be a positive integer including 0, and may be, for example, 4.

In addition, when the current block is in the decoder motion vector derivation mode, motion information used to generate the second prediction block may be up to K pieces. Here, K may be a positive integer including 0, and may be, for example, 4.

Also, when the current block is in the affine motion compensation mode, the maximum number of motion information used to generate the second prediction block may be K. Here, K may be a positive integer including 0, and may be, for example, 4.

18 and 19 are diagrams for explaining a sequence of deriving motion information used to generate a second prediction block. Motion information used to generate the second prediction block may be derived in a predetermined order in the encoder and decoder.

Referring to FIG. 18 , motion information may be derived in the order of an upper block, a left block, a lower block, and a right block based on the position of the current lower block.

Referring to FIG. 19 , in order to improve encoding efficiency, an order of deriving motion information used to generate a second prediction block may be determined based on a position of a current sub-block.

For example, blocks corresponding to the upper boundary area within the current block may derive motion information in the order of neighboring lower blocks adjacent to the current block: 1) neighboring upper blocks, 2) neighboring upper left blocks, and 3) neighboring upper right blocks.

In addition, blocks corresponding to the left boundary area within the current block may derive motion information in the order of 1) neighboring left blocks, 2) neighboring upper left blocks, and 3) neighboring lower left blocks adjacent to the current block.

In addition, blocks corresponding to the upper left boundary area within the current block may derive motion information in the order of neighboring lower blocks adjacent to the current block: 1) neighboring upper block, 2) neighboring left block, and 3) neighboring upper left block.

In addition, blocks corresponding to the upper right boundary area within the current block may derive motion information in the order of neighboring lower blocks adjacent to the current block: 1) upper neighboring block, 2) upper left neighboring block, and 3) upper right neighboring block.

In addition, blocks corresponding to the lower right boundary area within the current block can derive motion information in the order of 1) neighboring left blocks, 2) neighboring upper left blocks, and 3) neighboring lower left blocks, which are neighboring subblocks adjacent to the current block. .

As in the example of FIG. 19, the current sub-blocks within the current block are neighboring sub-blocks adjacent to the current sub-block within the current block: 1) neighboring upper block, 2) neighboring left block, 3) neighboring lower block, and 4) neighboring right block. , 5) the upper left block, 6) the lower left block, 7) the lower right block, and 8) the upper right block. Meanwhile, motion information may be derived in an order different from that shown in FIG. 19 .

Meanwhile, the motion information of the corresponding-position sub-block in the corresponding-position image may be derived in a lower order than neighboring sub-blocks spatially adjacent to the current sub-block. In addition, the motion information of the corresponding position sub-block in the corresponding position image may be derived in a higher order than neighboring sub-blocks spatially adjacent to the current sub-block.

In addition, motion information of a block encoded/decoded adjacent to the lower boundary region and the right boundary region of the reference block in the reference image may be derived at a lower order than neighboring subblocks spatially adjacent to the current subblock. In addition, motion information of a block encoded/decoded adjacent to the lower boundary region and the right boundary region of the reference block in the reference image may be derived in a higher order than neighboring subblocks spatially adjacent to the current subblock.

Motion information of neighboring sub-blocks adjacent to the current block or neighboring sub-blocks within the current block may be derived as motion information used to generate the second prediction block only when a specific condition is satisfied.

For example, when at least one of the neighboring sub-blocks adjacent to the current block and the neighboring sub-blocks within the current block exist, the motion information of the existing neighboring sub-blocks is converted into motion information used to generate the second prediction block. can be induced by

As another example, when at least one of the neighboring sub-blocks adjacent to the current block and the neighboring sub-blocks within the current block is in the inter prediction mode, motion information of at least one neighboring sub-block in the inter-prediction mode is obtained. It can be derived from motion information used to generate the second prediction block. On the other hand, if at least one of the neighboring sub-blocks adjacent to the current block and the neighboring sub-blocks within the current block is in the intra-prediction mode, motion information does not exist in the corresponding block, and thus the intra-prediction mode, at least Motion information of one neighboring sub-block may not be derived as motion information used to generate the second prediction block.

Meanwhile, at least one inter-prediction indicator among neighboring subblocks adjacent to the current block and neighboring subblocks within the current block is L0 prediction, L1 prediction, L2 prediction, L3 prediction, unidirectional prediction, bidirectional prediction, 3 When at least one of the four-directional prediction and the four-directional prediction is not indicated, motion information used to generate the second prediction block may not be derived.

Meanwhile, when the inter prediction indicator used to generate the second prediction block is not the same as the inter prediction indicator used to generate the first prediction block, motion information used to generate the second prediction block can be derived.

Also, when the motion vector used for generating the second prediction block is not the same as the motion vector used for generating the first prediction block, motion information used for generating the second prediction block may be derived.

In addition, when the reference image index used to generate the second prediction block is not the same as the reference image index used to generate the first prediction block, motion information used to generate the second prediction block may be derived.

In addition, when at least one of the motion vector and reference image index used for generating the second prediction block is not identical to at least one of the motion vector and reference image index used for generating the first prediction block, it is used for generating the second prediction block. Motion information to be can be derived.

In addition, in order to reduce complexity, when the inter-prediction indicator used to generate the first prediction block indicates unidirectional prediction, at least among motion vectors and reference image indices for L0 and L1 prediction directions used to generate the second prediction block When one is not identical to at least one of the motion vector and the reference picture index used for generating the first prediction block, motion information used for generating the second prediction block may be derived.

In addition, for complexity reduction, based on the inter prediction indicator used to generate the first prediction block, when the inter prediction indicator indicates bi-directional prediction, the L0 and L1 prediction directions used to generate the second prediction block When at least one of the combinations of the motion vector and the reference image index is not equal to at least one of the combinations of the motion vector and the reference image index for the L0 and L1 prediction directions used for generating the first prediction block, in generating the second prediction block Motion information to be used may be derived.

In addition, in order to reduce complexity, when at least one piece of motion information used for generating the second prediction block is not identical to at least one piece of motion information used for generating the first prediction block, the Motion information may be derived.

20 is a diagram for explaining an example of determining whether motion information usable for generation of a second prediction block is determined by comparing the POC of a reference image of a current sub-block with POCs of reference images of neighboring sub-blocks.

Referring to FIG. 20 , in order to reduce complexity, when the POC of the reference image of the current sub-block is the same as that of the reference images of neighboring sub-blocks, the motion information of the current sub-block is used to generate the second prediction block of the current sub-block. can

Meanwhile, in order to reduce complexity, as in the example of FIG. 20 , when the POC of the reference image used to generate the second prediction block is not the same as the POC of the reference image used to generate the first prediction block, the second prediction block is generated. Motion information used for may be derived.

Specifically, when the POC of the reference image used to generate the second prediction block is not the same as the POC of the reference image used to generate the first prediction block, the motion vector used to generate the second prediction block is used to generate the first prediction block. A motion vector used for generation of the second prediction block may be derived by performing motion vector scaling based on the reference image used in the reference image or the POC of the reference image.

21 is a diagram for explaining an embodiment of applying a weight when calculating a weighted sum of a first prediction block and a second prediction block.

When calculating the weighted sum of the first prediction block and the second prediction block, different weights may be used for each row or column according to the position of the sample in the block. In addition, a weighted sum between samples corresponding to the same positions in the first prediction block and the second prediction block may be calculated. In this case, when calculating the weighted sum for generating the final prediction block, at least one of a weight and an offset may be used.

Here, the weight may be a negative number less than 0 and a positive number greater than 0. And, the offset may be 0, a negative number less than 0, and a positive number greater than 0.

Meanwhile, when calculating the weighted sum of the first prediction block and the second prediction block, the same weight may be used at all sample locations for each prediction block.

Referring to FIG. 21, weights such as {3/4, 7/8, 15/16, 31/32} may be used for each row or each column for the first prediction block, and for each row for the second prediction block. Alternatively, weights such as {1/4, 1/8, 1/16, 1/32} may be used for each column. In this case, the same weight may be used for sample positions belonging to the same row or sample positions belonging to the same column.

As each weight is closer to the boundary of the current sub-block, a weight having a larger value may be used. Also, each weight may be applied to all samples in a sub-block.

21 (a), (b), (c), and (d) are generated using motion information of a neighboring upper block, motion information of a neighboring lower block, motion information of a neighboring left block, and motion information of a neighboring right block. 2 Each example of generating a prediction block may be shown. Here, the upper second prediction block, the lower second prediction block, the left second prediction block, and the right second prediction block are the motion information of the neighboring upper block, the motion information of the neighboring lower block, the motion information of the neighboring left block, and the neighboring right block. It may mean a second prediction block generated based on motion information of .

22 is a diagram for explaining an embodiment in which different weights are applied according to sample positions within blocks when calculating a weighted sum of a first prediction block and a second prediction block. In order to improve encoding efficiency, different weights may be used according to sample positions within blocks when calculating the weighted sum of the first prediction block and the second prediction block. That is, a weighted sum may be calculated with different weights according to positions of blocks spatially adjacent to the current sub-block. In addition, a weighted sum between samples corresponding to the same positions in the first prediction block and the second prediction block may be calculated.

Referring to FIG. 22, in the first prediction block, {1/2, 3/4, 7/8, 15/16, 31/32, 63/64, 127/128, 255/256, 511/ 512, 1023/1024} may be used, and in the second prediction block, {1/2, 1/4, 1/8, 1/16, 1/32, 1/64, 1/ 128, 1/256, 1/512, 1/1024} and the like may be used. Here, the weight values used in at least one or more of the upper second prediction block, the left second prediction block, the lower second prediction block, and the right second prediction block are the upper left second prediction block, the lower left second prediction block, and the lower right second prediction block. It may be greater than a weight value used in at least one of the second prediction block and the top-right second prediction block.

Meanwhile, weight values used in at least one or more of the upper second prediction block, the left second prediction block, the lower second prediction block, and the right second prediction block are the upper left second prediction block, the lower left second prediction block, and the lower right second prediction block. It may be the same as the weight value used in at least one of the second prediction block and the upper right second prediction block.

In addition, the weight of the second prediction block generated using the motion information of the corresponding-position sub-block in the corresponding-position image may be the same at all sample positions.

Also, the weight of the second prediction block generated using the motion information of the corresponding position sub-block in the corresponding position image may be the same as that of the first prediction block.

In addition, the weight of the second prediction block generated using motion information of an encoded/decoded block adjacent to the lower boundary region and the right boundary region of the reference block in the reference image may be the same at all sample positions.

In addition, the weight of the second prediction block generated using motion information of an encoded/decoded block adjacent to the lower boundary region and the right boundary region of the reference block in the reference image may be the same as that of the first prediction block.

Meanwhile, in order to reduce computational complexity, the weight value may vary according to the size of a motion vector of a neighboring sub-block adjacent to the current block or a neighboring sub-block within the current block.

For example, if the sum of the absolute values of the x-component and the y-component of motion vectors of neighboring sub-blocks is equal to or greater than a predefined value, {1/2, 3/4, 7/8, 15/16} can be used. On the other hand, if the sum of the absolute values of the x- and y-component motion vectors of neighboring sub-blocks is smaller than the predefined value, {7/8, 15/16, 31/32, 63/64} as the weight of the current sub-block can be used. In this case, the predefined value may be a positive integer including 0.

In addition, in order to reduce computational complexity, the weight value may vary according to the motion vector magnitude or motion vector direction of the current sub-block.

For example, if the absolute value of the motion vector x component of the current sub-block is equal to or greater than a predefined value, {1/2, 3/4, 7/8, 15/ 16} can be used. On the other hand, if the absolute value of the motion vector x component of the current sub-block is smaller than the predefined value, {7/8, 15/16, 31/32, 63/64} can be used as the weight of the left and right neighboring sub-blocks. can In this case, the predefined value may be a positive integer including 0.

For example, if the absolute value of the motion vector y component of the current sub-block is equal to or greater than a predefined value, {1/2, 3/4, 7/8, 15/ 16} can be used. On the other hand, if the absolute value of the motion vector y component of the current sub-block is smaller than the predefined value, {7/8, 15/16, 31/32, 63/64} is used as the weight of the upper and lower sub-blocks. can In this case, the predefined value may be a positive integer including 0.

For example, if the sum of the absolute values of the x component and the y component of the motion vector of the current sub-block is equal to or greater than a predefined value, {1/2, 3/4, 7/8 as the weight of the current sub-block , 15/16} can be used. On the other hand, if the sum of the absolute values of the x and y components of the motion vector of the current sub-block is smaller than the predefined value, {7/8, 15/16, 31/32, 63/64 as the weight of the current sub-block } can be used. In this case, the predefined value may be a positive integer including 0.

Meanwhile, the weighted sum calculation may not be performed at all sample locations within a sub-block, but may be performed on samples located in K rows/columns adjacent to each block boundary. In this case, K may be a positive integer including 0, and may be, for example, 1 or 2.

In addition, when the size of the current block is less than NxM, a weighted sum may be calculated for samples located in K rows/columns adjacent to each block boundary. In addition, when the current block is divided into sub-blocks and motion compensation is performed, a weighted sum may be calculated for samples located in K rows/columns adjacent to each block boundary. Here, K may be a positive integer including 0, and may be, for example, 1 or 2. Also, N and M may be positive integers, and for example, N and M may be 4 or 8 or more. N and M may be the same as or different from each other.

Also, based on the color components of the current block, a weighted sum may be calculated for samples located in K rows/columns adjacent to each block boundary. In this case, K may be a positive integer including 0, and may be, for example, 1 or 2. Also, when the current block is a luminance component, a weighted sum may be calculated for samples located in two rows/columns adjacent to each block boundary. Also, when the current block is a color difference component, a weighted sum may be calculated for samples located in one row/column adjacent to each block boundary.

In addition, when the current block is a merge mode and is at least one of an enhanced temporal motion vector prediction candidate and a spatial-temporal motion vector prediction candidate, a weighted sum may be calculated for samples located in K rows/columns adjacent to each block boundary. .

In addition, when the current block is in the decoder motion vector derivation mode, a weighted sum may be calculated for samples located in K rows/columns adjacent to each block boundary. Also, when the current block is in the affine motion compensation mode, a weighted sum may be calculated for samples located in K rows/columns adjacent to each block boundary. In this case, K may be a positive integer including 0, and may be, for example, 1 or 2.

Meanwhile, in order to reduce computational complexity, a weighted sum may be calculated for samples located in K rows/columns adjacent to each block boundary according to the size of a sub-block of the current block.

For example, when the size of a sub-block of the current block is 4x4, a weighted sum may be calculated for samples located in one, two, three, or four rows/columns adjacent to each block boundary. In addition, if the size of the sub-block of the current block is 8x8, samples located in 1, 2, 3, 4, 5, 6, 7, or 8 rows/columns adjacent to each block boundary A weighted sum can be calculated for At this time, K is a positive integer including 0, and can have as many rows/columns as the maximum value.

In addition, in order to reduce computational complexity, a weighted sum may be calculated for samples located in one or two fixed rows/columns adjacent to each block boundary within a sub-block.

In addition, in order to reduce computational complexity, a weighted sum may be calculated for samples located in K rows/columns adjacent to each block boundary according to the number of motion information used to generate the second prediction block. Here, K may be a positive integer including 0.

For example, when the number of motion information is less than a predefined value, a weighted sum may be calculated for samples located in two rows/columns adjacent to each block boundary.

In addition, when the number of motion information is equal to or greater than a predefined value, a weighted sum may be calculated for samples located in one row/column adjacent to each block boundary.

In addition, in order to reduce computational complexity, a weighted sum may be calculated for samples located in K rows/columns adjacent to each block boundary according to an inter-prediction indicator of the current block. K may be a positive integer including 0.

For example, when the inter-prediction indicator is unidirectional prediction, a weighted sum may be calculated for samples located in two rows/columns adjacent to each block boundary. In addition, when the inter-prediction indicator is bidirectional prediction, a weighted sum may be calculated for samples located in one row/column adjacent to each block boundary.

In addition, in order to reduce computational complexity, a weighted sum may be calculated for samples located in K rows/columns adjacent to each block boundary according to the POC of the reference image of the current block. Here, K may be a positive integer including 0.

For example, when the difference between the POC of the current image and the POC of the reference image is less than a predefined value, a weighted sum may be calculated for samples located in two rows/columns adjacent to each block boundary. On the other hand, when the difference between the POC of the current image and the POC of the reference image is equal to or greater than a predefined value, a weighted sum may be calculated for samples located in one row/column adjacent to each block boundary.

In addition, in order to reduce computational complexity, a weighted sum of samples located in K rows/columns adjacent to each block boundary according to the size of the motion vector of the neighboring subblock adjacent to the current block or the neighboring subblock within the current block this can be calculated. Here, K may be a positive integer including 0.

For example, if the sum of the absolute values of the motion vectors x and y components of the neighboring sub-blocks is equal to or greater than a predefined value, a weighted sum is calculated for samples located in two rows/columns adjacent to each block boundary. can On the other hand, when the sum of absolute values of motion vectors x and y components of neighboring sub-blocks is smaller than a predefined value, a weighted sum may be calculated for samples located in one row/column adjacent to each block boundary. In this case, the predefined value may be a positive integer including 0.

In addition, in order to reduce computational complexity, a weighted sum may be calculated for samples located in K rows/columns adjacent to each block boundary according to the magnitude or direction of the motion vector of the current sub-block. Here, K may be a positive integer including 0.

For example, when the absolute value of the motion vector x component of the current sub-block is equal to or greater than a predefined value, a weighted sum may be calculated for samples located in two rows/columns adjacent to the left and right boundaries. On the other hand, when the absolute value of the motion vector x component of the current sub-block is smaller than a predefined value, a weighted sum may be calculated for samples located in one row/column adjacent to the left and right boundaries. In this case, the predefined value may be a positive integer including 0.

For example, when the absolute value of the motion vector y component of the current sub-block is equal to or greater than a predefined value, a weighted sum may be calculated for samples located in two rows/columns adjacent to the upper and lower boundaries. On the other hand, when the absolute value of the motion vector y component of the current sub-block is smaller than a predefined value, a weighted sum may be calculated for samples located in one row/column adjacent to the upper and lower boundaries. In this case, the predefined value may be a positive integer including 0.

For example, when the sum of the absolute values of the x and y components of the motion vector is equal to or greater than a predefined value, a weighted sum may be calculated for samples located in two rows/columns adjacent to each block boundary. On the other hand, when the sum of the absolute values of the x and y components of the motion vector is smaller than a predefined value, a weighted sum may be calculated for samples located in one row/column adjacent to each block boundary. In this case, the predefined value may be a positive integer including 0.

23 is a diagram for explaining an embodiment in which a weighted sum of a first prediction block and a second prediction block is cumulatively calculated in a predetermined order when performing overlapping block motion compensation. The weighted sum of the first prediction block and the second prediction block may be calculated in a predetermined order in the encoder and decoder.

Referring to FIG. 23 , motion information may be derived in the order of an upper block, a left block, a lower block, and a right block adjacent to the current sub-block, and a second prediction block is generated using the derived motion information to generate the first prediction block. A weighted sum of the block and the second prediction block may be calculated. When calculating the weighted sum in the predetermined order, the weighted sum may be accumulated in the order to generate a final prediction block.

As in the example of FIG. 23, the weighted sum of the first prediction block and 1) the second prediction block generated using the motion information of the upper block may be calculated to generate the first weighted sum result block, and the generated second A weighted sum of 1 weighted sum result block and 2) a second prediction block generated using the motion information of the left block may be calculated to generate a second weighted sum result block, and the generated second weighted sum result block and 3 ) The weighted sum of the second prediction block generated using the motion information of the lower block may be calculated to generate a third weighted sum result block, and the generated third weighted sum result block and 4) the motion information of the right block A weighted sum of the generated second prediction blocks may be calculated to generate a final prediction block.

Meanwhile, an order of deriving motion information used in generating a second prediction block may be different from an order of calculating a weighted sum of the second prediction block when calculating a weighted sum of the first prediction block and the second prediction block.

24 is a diagram for explaining an embodiment in which a weighted sum of a first prediction block and a second prediction block is calculated during overlapped block motion compensation. In order to improve encoding efficiency, when calculating the weighted sum, the weighted sum is not accumulated and the motion information of the first prediction block and the upper block, the left block, the lower block, and the right block Weight of second prediction blocks generated using at least one or more The sum can be computed in any order.

In this case, second prediction blocks generated using at least one of motion information of the upper block, the left block, the lower block, and the right block may have the same weight. Also, the weight used for the second prediction block and the weight used for the first prediction block may be the same.

Referring to FIG. 24, a storage space equal to the number of first prediction blocks and second prediction blocks may be allocated, and when a final prediction block is generated, a weighted sum with the first prediction block may be calculated with the same weight between the second prediction blocks. .

*In addition, a weighted sum of the second prediction block generated using the motion information of the corresponding location sub-block in the corresponding location image may also be calculated with the first prediction block.

When the size of the current block is K samples or less, entropy encoding/decoding may be performed on information on whether overlapping block motion compensation is performed for the corresponding current block. In this case, K may be a positive integer, for example, 256.

In addition, when the size of the current block is larger than K samples or in a specific inter-prediction mode (eg, merge mode or enhanced motion vector prediction mode), entropy encoding information on whether overlapping block motion compensation is performed for the corresponding current block is performed. /Basically perform overlapped block motion compensation without decoding.

The encoder may perform motion prediction after subtracting the second prediction block from the original signal of the region corresponding to the boundary of the current block in the motion prediction step. In this case, when subtracting the second prediction block, a weighted sum of the second prediction block and the original signal may be calculated.

For the current block for which overlapped block motion compensation is not used, Enhanced Multiple Transform, which applies DCT (Discrete Cosine Transform)-based transforms and DST (Discrete Sine Transform)-based transforms to vertical/horizontal transforms, is not applied. may not be That is, the enhanced multi-transform can be applied only to the current block for which overlapped block motion compensation is used.

25 is a flowchart illustrating an image decoding method according to an embodiment of the present invention.

Referring to FIG. 25 , a first prediction block of the current block may be generated using motion information of the current block (S2510).

In addition, a second prediction block of at least one current sub-block may be generated using motion information of at least one neighboring sub-block of the current sub-block (S2520). Here, the neighboring sub-blocks may include neighboring sub-blocks of the sub-blocks of the corresponding location block temporally corresponding to the current block.

Meanwhile, when the current sub-block is not included in the left boundary area and the top boundary area of the current block, at least one second prediction is performed using motion information of at least one neighboring sub-block of the corresponding location block sub-block. blocks can be created.

In addition, when the current sub-block is not included in the left boundary region and the upper boundary region of the current block, a second prediction block is generated using motion information included in at least one of the merge list and the motion vector list of the current block. can create

Meanwhile, only when the current sub-block is included in at least one of the left boundary region and the upper boundary region of the current block, at least one second prediction block may be generated using motion information of at least one neighboring sub-block. there is.

Meanwhile, when the current sub-block is included in the left boundary region of the current block, at least one of the left neighboring sub-block, the upper-left neighboring sub-block, and the lower-left neighboring sub-block of the current sub-block is used. generates a second prediction block of, and when the current sub-block is included in an upper boundary region of the current block, at least one of an upper neighboring sub-block, an upper-left neighboring sub-block, and a lower-right neighboring sub-block of the current sub-block At least one second prediction block may be generated using motion information.

On the other hand, when the current sub-block is not included in the left boundary area and the top boundary area of the current block, the upper neighboring sub-block, the left neighboring sub-block, the lower neighboring sub-block, the right neighboring sub-block, and the upper-left corner of the current sub-block At least one second prediction block may be generated using motion information of at least one of a neighboring sub-block, a lower-left neighboring sub-block, a lower-right neighboring sub-block, and an upper-right neighboring sub-block.

Meanwhile, motion information of at least one neighboring subblock of the current subblock may be derived based on a predetermined order, and at least one second prediction block may be generated using the derived at least one motion information.

And, a final prediction block may be generated based on a weighted sum of the first prediction block of the current block and the second prediction block of the at least one current sub-block (S2530).

In this case, the weighted sum may be performed by applying different weights for each sample of the first prediction block and the second prediction block according to positions of neighboring sub-blocks used when generating the second prediction block.

Meanwhile, in the step of generating the final prediction block (S2530), when there are a plurality of second prediction blocks of the current sub-block, a weighted sum between the first prediction block of the current block and the second prediction block of the current sub-block is calculated. The final prediction block may be generated by summing at the same time.

Each step of the video decoding method of FIG. 25 can be equally applied to the video encoding method according to the present invention.

Meanwhile, the bitstream generated by the video encoding method according to the present invention may be stored in a recording medium.

The above embodiments can be performed in the same way in the encoder and decoder.

The order of applying the embodiment may be different in the encoder and decoder, and the order of applying the embodiment may be the same in the encoder and decoder.

The above embodiment may be performed for each of the luminance and color difference signals, and the above embodiment for the luminance and color difference signals may be equally performed.

The shape of a block to which the above embodiments of the present invention are applied may have a square shape or a non-square shape.

The above embodiments of the present invention may be applied according to the size of at least one of a coding block, a prediction block, a transform block, a block, a current block, a coding unit, a prediction unit, a transform unit, a unit, and a current unit. The size herein may be defined as a minimum size and/or a maximum size for the above embodiments to be applied, or may be defined as a fixed size to which the above embodiments are applied. Also, in the above embodiments, the first embodiment may be applied to the first size, and the second embodiment may be applied to the second size. That is, the above embodiments may be applied in a complex manner according to the size. Also, the above embodiments of the present invention may be applied only when the size is greater than or equal to the minimum size and less than or equal to the maximum size. That is, the above embodiments may be applied only when the block size is included within a certain range.

For example, the above embodiments can be applied only when the size of the current block is greater than or equal to 8x8. For example, the above embodiments can be applied only when the size of the current block is 4x4. For example, the above embodiments may be applied only when the size of the current block is 16x16 or less. For example, the above embodiments can be applied only when the size of the current block is greater than or equal to 16x16 and less than or equal to 64x64.

The above embodiments of the present invention may be applied according to a temporal layer. A separate identifier is signaled to identify a temporal layer to which the above embodiments are applicable, and the above embodiments can be applied to the temporal layer specified by the identifier. The identifier herein may be defined as the lowest layer and/or the highest layer to which the above embodiment is applicable, or may be defined as indicating a specific layer to which the above embodiment is applied. In addition, a fixed temporal layer to which the above embodiment is applied may be defined.

For example, the above embodiments may be applied only when the temporal layer of the current video is the lowest layer. For example, the above embodiments can be applied only when the temporal layer identifier of the current video is 1 or more. For example, the above embodiments may be applied only when the temporal layer of the current video is the highest layer.

A slice type to which the above embodiments of the present invention are applied is defined, and the above embodiments of the present invention can be applied according to the corresponding slice type.

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.

The foregoing embodiment includes examples of various aspects. It is not possible to describe all possible combinations to represent the various aspects, but those skilled in the art will recognize that other combinations are possible. Accordingly, it is intended that the present invention cover all other substitutions, modifications and variations falling within the scope of the following claims.

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 (19)

delete generating a first prediction block and a second prediction block for the current block; and
Generating a final prediction block for the current block using the first prediction block and the second prediction block;
The first prediction block is generated by performing first prediction on the current block,
The second prediction block is generated by performing second prediction on the current block;
The first prediction block and the second prediction block are generated using one or more merge candidates existing in one merge candidate list for the current block. According to claim 2,
Further comprising obtaining a first merge index and a second merge index for the merge candidate list,
The first prediction block is generated using a merge candidate indicated by the first merge index among candidates in the merge candidate list;
The second prediction block is generated using a merge candidate indicated by the second merge index among candidates in the merge candidate list. generating a first prediction block and a second prediction block for the current block; and
Generating a final prediction block for the current block using the first prediction block and the second prediction block;
The first prediction block is generated by performing first prediction on the current block,
The second prediction block is generated by performing second prediction on the current block;
The video decoding method of generating the final prediction block for the current block using a weighted sum of samples of the first prediction block and samples of the second prediction block. According to claim 4,
An image decoding method in which weight information on weights for the weighted sum is received through a bitstream. generating a first prediction block and a second prediction block for the current block; and
Generating a final prediction block for the current block using the first prediction block and the second prediction block;
The first prediction block is generated by performing first prediction on the current block,
The second prediction block is generated by performing second prediction on the current block;
The final prediction block for the current block is generated using a weighted sum of samples of the first prediction block and samples of the second prediction block,
For the weighted sum, one weight-pair is selected from among a plurality of weight-pairs;
A first weight of the selected weight-pair is applied to each sample of the first prediction block,
The second weight of the selected weight-pair is applied to each sample of the second prediction block. delete generating a first prediction block and a second prediction block for the current block; and
Generating a final prediction block for the current block using the first prediction block and the second prediction block,
The first prediction block is generated by performing first prediction on the current block,
The second prediction block is generated by performing second prediction on the current block;
The information for generating the first prediction block and the information for generating the second prediction block correspond to one or more merge candidates existing in one merge candidate list for the current block. According to claim 8,
Further comprising generating a first merge index and a second merge index for the merge candidate list,
The information for generating the first prediction block corresponds to a merge candidate indicated by the first merge index among candidates in the merge candidate list,
The information for generating the second prediction block corresponds to a merge candidate indicated by the second merge index among candidates in the merge candidate list. generating a first prediction block and a second prediction block for the current block; and
Generating a final prediction block for the current block using the first prediction block and the second prediction block,
The first prediction block is generated by performing first prediction on the current block,
The second prediction block is generated by performing second prediction on the current block;
The video encoding method of generating the final prediction block for the current block using a weighted sum of samples of the first prediction block and samples of the second prediction block. According to claim 10,
An image encoding method in which a bitstream including weight information about weights for the weighted sum is generated. generating a first prediction block and a second prediction block for the current block; and
Generating a final prediction block for the current block using the first prediction block and the second prediction block,
The first prediction block is generated by performing first prediction on the current block,
The second prediction block is generated by performing second prediction on the current block;
The final prediction block for the current block is generated using a weighted sum of samples of the first prediction block and samples of the second prediction block,
For the weighted sum, one weight-pair is selected from among a plurality of weight-pairs;
A first weight of the selected weight-pair is applied to each sample of the first prediction block,
The second weight of the selected weight-pair is applied to each sample of the second prediction block. A computer-readable recording medium storing a bitstream generated by the image encoding method of claim 8. delete In the computer readable recording medium containing a bit stream,
The bitstream is
Information about the prediction of the current block
including,
A first prediction block and a second prediction block for the current block are generated using information about the prediction of the current block;
A final prediction block for the current block is generated using the first prediction block and the second prediction block;
The first prediction block is generated by performing first prediction on the current block,
The second prediction block is generated by performing second prediction on the current block;
The first prediction block and the second prediction block are generated using one or more merge candidates existing in one merge candidate list for the current block. According to claim 15,
A first merge index and a second merge index for the merge candidate list are obtained;
The first prediction block is generated using a merge candidate indicated by the first merge index among candidates in the merge candidate list;
The second prediction block is generated using a merge candidate indicated by the second merge index among candidates in the merge candidate list. In the computer readable recording medium containing a bit stream,
The bitstream is
Information about the prediction of the current block
including,
A first prediction block and a second prediction block for the current block are generated using information about the prediction of the current block;
A final prediction block for the current block is generated using the first prediction block and the second prediction block;
The first prediction block is generated by performing first prediction on the current block,
The second prediction block is generated by performing second prediction on the current block;
Wherein the final prediction block for the current block is generated using a weighted sum of samples of the first prediction block and samples of the second prediction block. According to claim 17,
A computer-readable recording medium in which weight information on weights for the weighted sum is received through a bitstream. In the computer readable recording medium containing a bit stream,
The bitstream is
Information about the prediction of the current block
including,
A first prediction block and a second prediction block for the current block are generated using information about the prediction of the current block;
A final prediction block for the current block is generated using the first prediction block and the second prediction block;
The first prediction block is generated by performing first prediction on the current block,
The second prediction block is generated by performing second prediction on the current block;
The final prediction block for the current block is generated using a weighted sum of samples of the first prediction block and samples of the second prediction block,
For the weighted sum, one weight-pair is selected from among a plurality of weight-pairs;
A first weight of the selected weight-pair is applied to each sample of the first prediction block,
A second weight of the selected weight-pair is applied to each sample of the second prediction block.

Images