KR20230096953A - A method for encoding/decoding a video - Google Patents

Abstract

The present invention relates to a method of performing motion compensation using motion vector prediction. A video decoding method for this may include the steps of: obtaining a quantized residual signal for a current block; dequantizing the quantized residual signal; and determining a transformation technique for inversely transforming the residual signal. At this time, the inverse transformation includes a primary transformation and a secondary transformation. At least one of the primary transformation technique and the secondary transformation technique may be derived from a decoded restored block surrounding the current block.

Description

Video encoding/decoding method {A METHOD FOR ENCODING/DECODING A VIDEO}

The present invention relates to a method and apparatus for encoding/decoding an image, and more particularly, to a method and apparatus for deriving encoding information of a current block using encoding information of neighboring blocks.

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.

In the conventional motion compensation, since only spatial motion vector candidates, temporal motion vector candidates, and zero motion vector candidates are added to the motion vector candidate list and only unidirectional prediction and bidirectional prediction are used, there is a limit to improvement in coding efficiency.

An object of the present invention is to provide a method and apparatus for deriving encoding information of a current block from reconstruction blocks adjacent to the current block.

An object of the present invention is to provide a method and apparatus for encoding/decoding a difference value between a motion vector difference value around a current block and a motion vector difference value of the current block.

According to the present invention, an image encoding method includes generating a prediction signal for a current block, generating a residual signal for the current block based on the prediction signal, and a conversion technique for transforming the residual signal. determining, and quantizing the residual signal. In this case, the transform includes a primary transform and a secondary transform, and at least one of the primary transform technique and the secondary transform technique may be derived from an encoded reconstruction block adjacent to the current block.

An image decoding method according to the present invention may include obtaining a quantized residual signal for a current block, inverse-quantizing the quantized residual signal, and determining a transform technique for inverse transforming the residual signal. can In this case, the inverse transform includes a primary transform and a secondary transform, and at least one of the primary transform technique and the secondary transform technique may be derived from a decoded reconstruction block adjacent to the current block.

In the video encoding method or the video decoding method, when the current block is coded by intra-prediction, at least one of the primary transform technique and the secondary transform technique has an intra-prediction mode identical to that of the current block. can be derived from blocks.

In the video encoding method or the video decoding method, when the primary transform technique of a neighboring block having the same intra-prediction mode as the current block indicates transform skip, the primary transform technique and the secondary transform technique for the current block A transform technique may be determined as a transform skip.

In the video encoding method or the video decoding method, the secondary transform technique may be derived from the same neighboring block as the current block.

In the video encoding method or the video decoding method, when the current block is coded by inter-prediction, at least one of the primary transform technique and the secondary transform technique is performed from a neighboring block having the same motion information as the current block. can be induced.

In the video encoding method or the video decoding method, the motion information may include at least one of a motion vector, a reference video index, and a reference picture direction.

According to the present invention, there is an effect of improving encoding/decoding efficiency by providing a method and apparatus for deriving encoding information of a current block from reconstruction blocks adjacent to the current block.

According to the present invention, encoding/decoding efficiency can be improved by providing a method and apparatus for encoding/decoding a difference between a motion vector difference value around a current block and a motion vector difference value of the current block.

1 is a block diagram showing a configuration according to an embodiment of an encoding device to which the present invention is applied.
2 is a block diagram showing a configuration according to an embodiment of a decoding device to which the present invention is applied.
3 is a diagram schematically illustrating a division structure of an image when encoding and decoding an image.
4 is a diagram illustrating a form of a prediction unit (PU) that may be included in a coding unit (CU).
5 is a diagram illustrating a form of a transform unit (TU) that may be included in a coding unit (CU).
6 is a diagram for explaining an embodiment of an intra-prediction process.
7 is a diagram for explaining an embodiment of an inter-screen prediction process.
8 is a diagram for explaining a transform set according to an intra prediction mode.
9 is a diagram for explaining a conversion process.
10 is a diagram for explaining scanning of quantized transform coefficients.
11 is a diagram for explaining block division.
12 is a diagram exemplified to explain encoding/decoding units according to block division types.
13 is a flowchart illustrating a process of determining whether to decode information related to binary tree partitioning.
14 is a flowchart illustrating a process of determining whether to decode information related to binary tree partitioning.
15 to 17 are diagrams for explaining an example of a case in which binary tree partitioning is no longer performed on blocks having a predetermined size or less.
18 is a flowchart illustrating a process of determining whether to derive encoding information for a residual signal of a current block from a neighboring block when the current block is coded by intra prediction.
19 is a flowchart illustrating a process of determining whether to derive encoding information for a residual signal of a current block from a neighboring block when the current block is coded by inter-prediction.
20 is a flowchart illustrating a process of decoding a motion vector of a current block.
21 is a diagram for explaining an example of deriving a spatial motion vector candidate.
22 is a diagram for explaining an example of deriving a temporal motion vector candidate.
23 is a diagram for explaining a second motion vector difference value.

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 being "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 indicate 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: May mean a device that performs encoding.

Decoder: This may mean a device that performs decryption.

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

Block: An MxN array of samples, where M and N represent positive integer values, and a block can often refer to a two-dimensional array of samples.

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

Unit: May mean a unit of video encoding and decoding. In encoding and decoding of an image, a unit may be a region created 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 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 transform unit, and the like, a size of the unit, a depth of the unit, and an encoding and decoding order of the unit.

Reconstructed Neighbor Unit: This may refer to a unit that has already been spatially/temporally encoded or decoded around a unit to be encoded/decoded and reconstructed. In this case, the reconstructed neighboring unit may mean a reconstructed neighboring block.

Neighbor block: This may mean a block adjacent to an encoding/decoding target block. A block adjacent to an encoding/decoding object block may mean a block whose boundary abuts with the encoding/decoding object block. A neighboring block may refer to a block located at an adjacent vertex of an encoding/decoding target block. A neighboring block may mean a restored neighboring block.

Unit Depth: It means the degree to which a unit is divided. In a tree structure, the root node has the shallowest depth and the leaf node has the deepest depth.

Symbol: It may mean a unit syntax element to be coded/decoded, a coding parameter, a value of a transform coefficient, and the like.

Parameter Set: Among structures within a bitstream, it may correspond to header information, and includes a video parameter set, a sequence parameter set, a picture parameter set, and an adaptation parameter set. At least one of (adaptation parameter sets) may be included in the parameter set. In addition, the parameter set may have a meaning including slice header and tile header information.

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

Prediction Unit: It is a basic unit when inter-prediction or intra-prediction and compensation are performed, and one prediction unit may be divided into a plurality of small-sized partitions. In this case, each of a plurality of partitions becomes a basic unit for performing the prediction and compensation, and a partition into which a prediction unit is divided may also be referred to as a prediction unit. The prediction unit may have various sizes and shapes, and in particular, the shape of the prediction 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.

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

Reference Picture List: This may mean a list including one or more reference pictures used for inter-picture 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: In inter-prediction, it can mean the inter-prediction direction (uni-directional prediction, bi-directional prediction, etc.) It may mean the number of reference images used when performing inter-prediction or motion compensation on a block to be encoded/decoded.

Reference Picture Index: This may mean an index for a specific reference picture in a reference picture list.

Reference Picture: This may refer to a picture referenced by a specific unit for inter-picture prediction or motion compensation, and a reference picture may also be referred to as a reference picture.

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 predicting a motion vector, it may mean a unit that becomes a prediction candidate or a motion vector of the unit.

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, which may also be referred to as an index of a motion vector predictor.

Motion information: information including at least one of reference image list information, reference image, motion vector candidate, motion vector candidate index, as well as a motion vector, reference image index, and inter prediction indicator can mean

Merge Candidate List: This may mean a list constructed using merge candidates.

Merge Candidate: may include a spatial merge candidate, a temporal merge candidate, a combined merge candidate, a combined bi-prediction merge candidate, a zero merge candidate, and the like, and the merge candidate includes prediction type information, each It may include motion information such as a reference picture index for the list and a motion vector.

Merge Index: This may mean 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 piece of motion information of a merge candidate.

Transform Unit: May mean a basic unit when encoding/decoding a residual signal such as transform, inverse transform, quantization, inverse quantization, and transform coefficient encoding/decoding, and one transform unit It can be divided into a plurality of small-sized transform units. The conversion unit may have various sizes and shapes, and in particular, the shape of the conversion 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.

Scaling: This may refer to a process of multiplying a transform coefficient level by a factor, and a transform coefficient may be generated as a result. Scaling can also be called dequantization.

Quantization Parameter: May mean a value used when scaling a transform coefficient level in quantization and inverse quantization. In this case, the quantization parameter may be a value mapped to a quantization step size.

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

Scan: It can mean a method of arranging the order of coefficients in a block or matrix. For example, arranging a 2D array into a 1D array is called a scan, and a 1D array is converted into a 2D array. Alignment can also be called a scan or an inverse scan.

Transform Coefficient: A coefficient value generated after performing a transform. In the present invention, a quantized transform coefficient level obtained by applying quantization to the transform coefficient may also be included in the meaning of the transform coefficient.

Non-zero transform coefficient: This may mean a transform coefficient whose magnitude is not 0 or a transform coefficient level whose magnitude is not 0.

Quantization Matrix: This may refer to 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: This may mean each element in a quantization matrix. Quantization matrix coefficients may also be referred to as matrix coefficients.

Default Matrix: This may mean a predetermined quantization matrix predefined in an encoder and a decoder.

Non-default matrix: This may mean a quantization matrix transmitted/received by a user and not predefined in an encoder and a decoder.

Coding Tree Unit: It may be composed of two chrominance component (Cb, Cr) coding tree blocks related to one luminance component (Y) coding tree 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. Like segmentation of an input image, 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.

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.

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 a video encoding device or an image encoding device. A video may include one or more images. The encoding apparatus 100 may sequentially encode one or more images of a video according to time.

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. 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 predictor 120 may use pixel values of blocks already coded adjacent to 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, the motion vector may be a 2D vector used for inter prediction. Also, the motion vector may indicate an offset between the current image and the reference image. Here, inter prediction may mean inter prediction.

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 corresponding coding unit based on the coding unit are skip mode, merge mode, and AMVP mode (AMVP mode). ), it is possible to determine which of the current picture reference modes is used, and inter-picture prediction or motion compensation can be performed according to each mode. Here, the current picture reference mode may mean a prediction mode using a pre-reconstructed region in the current picture to which the encoding target block belongs. A motion vector for a current picture reference mode may be defined to specify the pre-reconstructed region. Whether the encoding object block is encoded in the current picture reference mode can be encoded using the reference image index of the encoding object block.

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

The quantization unit 140 may generate a quantized transform coefficient level by quantizing the transform coefficient according to a quantization parameter, and may output the quantized transform coefficient 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 for decoding an image in addition to pixel information of the 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. Therefore, compression performance of image encoding can be improved through entropy encoding. 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 performs arithmetic encoding using the derived binarization method or probability model. You may.

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. For example, by scanning the coefficients of blocks using up right scanning, they can be changed into a one-dimensional vector form. Depending on the size of the transform unit and the intra-prediction mode, instead of upright scan, vertical scan for scanning 2-dimensional block-type coefficients in a column direction and horizontal scan for scanning 2-dimensional block-type coefficients in a row direction may be used. That is, it is possible to determine which scan method among upright scan, vertical scan, and horizontal scan is used according to the size of the transform unit and the intra-prediction mode.

Coding parameters may include not only information encoded in an encoder and transmitted to a decoder, such as a syntax element, but also information derived from an encoding or decoding process, and may mean information necessary for encoding or decoding an image. there is. For example, block size, block depth, block division information, unit size, unit depth, unit division information, quad tree division flag, binary tree division flag, binary tree division direction, intra-prediction mode, Intra-prediction direction, reference sample filtering method, prediction block boundary filtering method, filter tap, filter coefficient, inter-prediction mode, motion information, motion vector, reference image index, inter-prediction direction, inter-prediction indicator, reference image list , motion vector predictor, motion vector candidate list, whether to use motion merge mode, motion merge candidate, motion merge candidate list, whether to use skip mode, interpolation filter type, motion vector size, motion vector expression accuracy , transform type, transform size, additional (quadratic) transform information, residual signal presence information, coded block pattern, coded block flag, quantization parameter, quantization matrix, in-loop filter Information, filter application information in loop, filter coefficient in loop, binarization/inverse binarization method, context model, context bin, bypass bin, transform coefficient, transform coefficient level, transform coefficient level scanning method, image display/output order, slice At least one value or a combination of identification information, slice type, slice division information, tile identification information, tile type, tile division information, picture type, bit depth, luminance signal, or color difference signal information may be included in the coding parameter. there is.

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 a difference between the original signal and the predicted signal. Alternatively, the residual signal may be a signal generated by transforming and quantizing the difference between the original signal and the prediction signal. The residual block may be a residual signal in units of blocks.

When the encoding apparatus 100 performs encoding through inter prediction, the encoded current image may be used as a reference image for other image(s) to be processed later. Accordingly, the encoding device 100 may decode the encoded current image again and store the decoded image as a reference image. Inverse quantization and inverse transformation of the current image encoded for decoding may be processed.

The quantized coefficient may be dequantized by the inverse quantization unit 160. It may be inversely transformed in the inverse transform unit 170. The inverse quantized and 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 inverse transformed coefficients and the prediction 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. can 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, a strong filter or a weak filter may be applied according to the required deblocking filtering strength. In addition, in applying the deblocking filter, when vertical filtering and horizontal filtering are performed, horizontal filtering and vertical filtering may be processed in parallel.

The sample adaptive offset may add an appropriate offset value to a pixel value to compensate for a coding error. 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. In order to perform offset correction for a specific picture, after dividing the pixels included in the image into a certain number of areas, determining the area to be offset and applying the offset to the area, or offset by considering the edge information of each pixel method can 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 one filter to be applied to the corresponding group. Information related to whether or not to apply the adaptive loop filter may be transmitted for each coding unit (CU) of the luminance signal, and the shape and filter coefficients of the adaptive loop filter to be applied may vary according to each block. In addition, the same type (fixed type) of the adaptive loop filter may be applied regardless of the characteristics of the block to be applied.

A reconstructed block 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 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 perform decoding on a bitstream in an intra mode or an inter mode. Also, the decoding apparatus 200 may generate a restored image through decoding and output the restored 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 obtain a reconstructed residual block from the input bitstream and generate a prediction block. When the reconstructed residual block and the prediction block are obtained, the decoding apparatus 200 may generate a reconstructed block that is a decoding target block 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 transform coefficient levels. Here, the entropy decoding method may be similar to the above-described entropy encoding method. For example, the entropy decoding method may be a reverse process of the above-described entropy encoding method.

The 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. For example, it can be changed into a 2D block form by scanning coefficients of a block using up right scanning. Depending on the size of the conversion unit and the intra-prediction mode, vertical scan or horizontal scan may be used instead of upright scan. That is, it is possible to determine which scan method among upright scan, vertical scan, and horizontal scan is used according to the size of the transform unit and the intra-prediction mode.

The quantized transform coefficient level may be inversely quantized in the inverse quantization unit 220 and inversely transformed in the inverse transformation unit 230 . As a result of inverse quantization and inverse transformation of the quantized transform coefficient level, a reconstructed residual block may be generated. At this time, the inverse quantization unit 220 may apply a quantization matrix to the quantized transform coefficient 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, the motion compensation method of the prediction unit included in the corresponding coding unit based on the coding unit is skip mode, merge mode, AMVP mode, and current picture reference mode. It is possible to determine which method is used, and motion compensation can be performed according to each mode. Here, the current picture reference mode may mean a prediction mode using a pre-reconstructed region in the current picture to which the decoding target block belongs. A motion vector for a current picture reference mode may be used to specify the pre-reconstructed region. A flag or index indicating whether the decoding object block is a block coded in the current picture reference mode may be signaled or may be inferred through a reference picture index of the decoding object block. The current picture in the current picture reference mode may exist at a fixed position (eg, a position with a reference image index of 0 or the last position) within the reference picture list for the decoding target block. Alternatively, it may be variably positioned in the reference picture list, and for this purpose, a separate reference picture index indicating the location of the current picture may be signaled.

The reconstructed residual block and the predicted block may be added through an adder 255. A block generated by adding the reconstructed residual block and the predicted block may pass through the filter unit 260 . 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. The 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. Here, the coding unit may mean a coding unit. A unit may be a term collectively referring to 1) a syntax element and 2) a block including image samples. For example, “division of a unit” may mean “division of a block corresponding to a 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.

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). One unit may be hierarchically divided with depth information based on a tree structure. Each divided sub-unit may have depth information. Since the depth information indicates the number and/or degree of division of the unit, it may include information about the size of the sub-unit.

The division structure may refer to a distribution of Coding Units (CUs) within the LCU 310 . A CU may be a unit for efficiently encoding an image. 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 The divided CU may be recursively divided into a plurality of CUs having reduced horizontal and vertical sizes in the same manner.

In this case, the division of the CU may be recursively performed up to a predefined depth. Depth information may be information representing the size of a CU and may be stored for each CU. 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 and vertical sizes of the CU are reduced by division. For each depth, a CU that is not split may have a size of 2Nx2N. In the case of a CU to be divided, a 2Nx2N CU may be divided into a plurality of NxN CUs. The size of N is halved for each increase in depth by one.

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. For example, when a coding unit having a size of 32x32 is horizontally divided into two coding units, each of the two divided coding units may have a size of 32x16. 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.

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

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 split information is 0, the CU may not be split, and if the value of the split information is 1, the CU may be split.

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

Among the CUs divided from the LCU, a CU that is not further divided may be divided into one or more prediction units (PUs). This process may also be referred to as segmentation.

A PU may be a basic unit for prediction. A PU may be encoded and decoded in any one of a skip mode, an inter-screen mode, and an intra-screen mode. A PU may be divided into various types according to modes.

Also, a coding unit is not divided into prediction units, and a coding unit and a prediction unit may have the same size.

As shown in FIG. 4 , in skip mode, there may not be a split within a CU. In the skip mode, the 2Nx2N mode 410 having the same size as the CU without division may be supported.

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

One coding unit may be divided into one or more prediction units, and one prediction unit may be divided into one or more prediction units.

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

For example, when one prediction unit is divided into two prediction units, the horizontal or vertical size of the two prediction units may be half the size compared to the horizontal or vertical size of the prediction unit before being divided. . For example, when a prediction unit having a size of 32x32 is vertically divided into two prediction units, each of the two prediction units may have a size of 16x32. For example, when a prediction unit having a size of 32x32 is horizontally divided into two prediction units, each of the two prediction units may have a size of 32x16. When one prediction unit is split into two prediction units, it can be said that the prediction unit is split in the form of a binary-tree.

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

A transform unit (TU) may be a basic unit used for transform, quantization, inverse transform, and inverse quantization processes within a CU. A TU may have a square shape or a rectangular shape. The TU may be determined dependent on the size and/or shape of the CU.

Among the CUs split from the LCU, a CU that is no longer split into CUs may be split into one or more TUs. In this case, the division structure of the TU may be a quad-tree structure. For example, as shown in FIG. 5 , one CU 510 may be divided one or more times according to a quadtree structure. When one CU is split more than once, it can be said to be split recursively. Through division, one CU 510 may be composed of TUs of various sizes. Alternatively, the CU may be divided into one or more TUs based on the number of vertical lines and/or horizontal lines dividing the CU. A CU may be divided into symmetric TUs or asymmetric TUs. For division into asymmetric TUs, information on the size/shape of TUs may be signaled or may be derived from information on the size/shape of CUs.

Also, the coding unit is not divided into transform units, and the coding unit and the transform unit may have the same size.

One coding unit may be divided into one or more transform units, and one transform unit may be divided into one or more transform units.

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

For example, when one transform unit is divided into two transform units, the horizontal or vertical size of the two divided transform units may have a half size compared to the horizontal or vertical size of the transform unit before being divided. . For example, when a transform unit having a size of 32x32 is vertically divided into two transform units, each of the two divided transform units may have a size of 16x32. For example, when a transform unit having a size of 32x32 is horizontally divided into two transform units, each of the two divided transform units may have a size of 32x16. When one conversion unit is divided into two conversion units, it can be said that the conversion unit is divided in the form of a binary tree.

When performing transformation, the residual block may be transformed using at least one of a plurality of pre-defined transformation methods. For example, discrete cosine transform (DCT), discrete sine transform (DST), or KLT may be used as a plurality of pre-defined transform methods. Which transform method is applied to transform the residual block may be determined using at least one of inter-prediction mode information of the prediction unit, intra-prediction mode information, and size/shape of the transform block, and in certain cases, the transform method is indicated. Information may be signaled.

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

The intra-prediction mode may be a non-directional mode or a directional mode. The non-directional mode may be a DC mode or a planar mode, and the directional mode may be a prediction mode having a specific direction or angle, and the number may be one or more M. The directional mode may be expressed as at least one of a mode number, a mode value, a mode number, and a mode angle.

The number of intra-prediction modes may be one or more N including the non-directional and directional modes.

The number of intra-prediction modes may vary according to the size of a block. For example, the block size may be 67 in the case of 4x4 or 8x8, 35 in the case of 16x16, 19 in the case of 32x32, and 7 in the case of 64x64.

The number of intra-prediction modes may be fixed to N regardless of the block size. For example, at least one of 35 and 67 may be fixed regardless of the size of the block.

The number of intra-prediction modes may be different according to the type of color component. For example, the number of prediction modes may be different depending on whether the color component is a luma signal or a chroma signal.

In-picture encoding and/or decoding may be performed using sample values or encoding parameters included in adjacent reconstructed blocks.

In order to encode/decode the current block through intra-prediction, a step of checking whether or not samples included in neighboring reconstructed blocks are available as reference samples of the block to be encoded/decoded may be performed. If there are samples that cannot be used as reference samples of a block to be encoded/decoded, copy sample values to samples that cannot be used as reference samples by using at least one of samples included in adjacent reconstructed blocks and/or It may be interpolated and used as a reference sample of a block to be encoded/decoded.

During intra-prediction, a filter may be applied to at least one of reference samples and prediction samples based on at least one of an intra-prediction mode and a size of an encoding/decoding target block. In this case, the encoding/decoding target block may mean a current block, and may mean at least one of a coding block, a prediction block, and a transform block. The type of filter applied to the reference sample or prediction sample may be different according to at least one of the intra prediction mode or size/shape of the current block. The type of filter may vary according to at least one of the number of filter taps, filter coefficient values, and filter strength.

Among the intra-prediction modes, the non-directional planar mode, when generating a prediction block of a target encoding/decoding block, sets the sample value in the prediction block according to the sample position: the top reference sample of the current sample, the left reference sample of the current sample, It can be generated as a weighted sum of the top-right reference sample of the current block and the bottom-left reference sample of the current block.

Among the intra-prediction modes, the non-directional DC mode can be generated as an average value of top reference samples of the current block and left reference samples of the current block when generating a prediction block of a target encoding/decoding block. In addition, filtering may be performed using reference sample values for one or more top rows and one or more left columns adjacent to the reference sample in the encoding/decoding block.

In the case of a plurality of angular modes among intra-prediction modes, prediction blocks may be generated using the upper right and/or lower left reference samples, and the directional modes may have different directivity. Interpolation in units of real numbers may be performed to generate predicted sample values.

To perform the intra-prediction method, the intra-prediction mode of the current prediction block can be predicted from the intra-prediction modes of prediction blocks existing around the current prediction block. When predicting the intra-prediction mode of the current prediction block using the mode information predicted from the prediction mode in the neighboring picture, if the intra-prediction mode of the current prediction block and the neighboring prediction block are the same, the current prediction is made using predetermined flag information It is possible to transmit information that the intra prediction mode of the block and the neighboring prediction block are the same, and if the intra prediction mode of the current prediction block and the neighboring prediction block are different, entropy encoding is performed and the intra prediction mode of the block to be encoded/decoded is performed. information can be encoded.

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

The rectangle shown in FIG. 7 may represent an image (or picture). Also, arrows in FIG. 7 may indicate prediction directions. That is, an image may be encoded and/or decoded according to a prediction direction. Each image may be classified into an I-picture (Intra Picture), a P-picture (Uni-predictive Picture), and a B-picture (Bi-predictive Picture) according to an encoding type. Each picture may be coded and decoded according to the coding type of each picture.

When an image to be encoded is an I-picture, the image itself may be intra-encoded without inter-prediction. When an image to be encoded is a P picture, the image may be encoded through inter prediction or motion compensation using a reference image only in a forward direction. If an image to be encoded is a B picture, it can be coded through inter prediction or motion compensation using reference pictures in both forward and backward directions, and inter prediction or motion using reference pictures in either forward or backward direction. It can be encoded through compensation. Here, when the inter-prediction mode is used, the encoder may perform inter-prediction or motion compensation, and the decoder may perform motion compensation corresponding thereto. Pictures of P pictures and B pictures that are encoded and/or decoded using reference pictures may be regarded as pictures in which inter prediction is used.

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. Also, inter-picture prediction may use the above-described skip mode.

A reference picture may be at least one of a picture before the current picture or a picture after the current picture. In this case, inter-prediction may perform prediction on a block of the current picture based on the reference picture. Here, the reference picture may mean an image used for prediction of a block. In this case, the region within the reference picture may be specified by using a reference picture index (refIdx) indicating the reference picture and a motion vector to be described later.

Inter-prediction may select a reference picture and a reference block corresponding to a current block within the reference picture, and generate a prediction block for the current block using the selected reference block. The current block may be a block currently being encoded or decoded among blocks of the current picture.

Motion information may be derived during inter prediction by each of the encoding device 100 and the decoding device 200 . Also, the derived motion information can be used to perform inter-picture prediction. At this time, the encoding device 100 and the decoding device 200 use motion information of a reconstructed neighboring block and/or motion information of a collocated block (col block) to achieve encoding and/or decoding efficiency can improve A collocated block may be a block corresponding to a spatial position of a block to be encoded/decoded in an already reconstructed collocated picture (col picture). The reconstructed neighboring block may be a block in the current picture and a block already reconstructed through encoding and/or decoding. In addition, the reconstruction block may be a block adjacent to the encoding/decoding object block and/or a block located at an outer corner of the encoding/decoding object block. Here, the block located at the outer corner of the encoding/decoding target block is a block vertically adjacent to a neighboring block horizontally adjacent to the encoding/decoding target block or a block horizontally adjacent to a neighboring block vertically adjacent to the encoding/decoding target block. can

Each of the encoding apparatus 100 and the decoding apparatus 200 may determine a block spatially located at a position corresponding to a block to be encoded/decoded in a collocated picture, and determine a predefined relative position with respect to the determined block. can The predefined relative position may be a position inside and/or outside a block spatially corresponding to the encoding/decoding target block. Also, each of the encoding apparatus 100 and the decoding apparatus 200 may derive a collocated block based on the determined relative position. 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 change according to a prediction mode of a block to be encoded/decoded. For example, prediction modes applied for inter-prediction may include advanced motion vector prediction (AMVP) and merge mode. Here, the merge mode may be referred to as a motion merge mode.

For example, when AMVP is applied as a prediction mode, each of the encoding apparatus 100 and the decoding apparatus 200 uses a motion vector of a reconstructed neighboring block and/or a motion vector of a collocated block to list motion vector candidates. (motion vector candidate list) can be created. A motion vector of a reconstructed neighboring block and/or a motion vector of a collocated block may be used as a motion vector candidate. Here, a motion vector of a 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.

A bitstream generated by the encoding device 100 may include a motion vector candidate index. That is, 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 motion vector candidate index may be transmitted from the encoding apparatus 100 to the decoding apparatus 200 through a bitstream.

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. .

The encoding apparatus 100 may calculate a motion vector difference (MVD) between a motion vector of a block to be encoded and a motion vector candidate, and entropy-encode the MVD. The bitstream may include an entropy-encoded MVD. The MVD may be transmitted from the encoding device 100 to the decoding device 200 through a bitstream. At this time, the decoding apparatus 200 may entropy-decode the received MVD from the bitstream. The decoding apparatus 200 may derive the motion vector of the decoding object block through the sum of the 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 transmitted from the encoding apparatus 100 to the decoding apparatus 200 through a bitstream. The decoding apparatus 200 may predict the motion vector of the decoding object block using motion information of neighboring blocks, and may derive the motion vector of the decoding object block using the predicted motion vector and the motion vector difference. 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. Merge mode may mean applying motion information of one block to another block as well. When merge mode is applied, each of the encoding device 100 and the decoding device 200 may generate a merge candidate list using motion information of a reconstructed neighboring block and/or motion information of a collocated block. can 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.

In this case, the merge mode may be applied in units of CUs or units of PUs. When the merge mode is performed in units of CUs or PUs, the encoding device 100 may entropy-encode predefined information to generate a bitstream and transmit it to the decoding device 200. A bitstream may include predefined information. The predefined information includes 1) a merge flag, which indicates whether merge mode is to be performed for each block partition, and 2) which block to merge with among neighboring blocks adjacent to the encoding target block. It may include a merge index, which is information about. For example, neighboring blocks of the encoding object block may include a left adjacent block of the encoding object block, an upper adjacent block of the encoding object block, and a temporal adjacent block of the encoding object block.

The merge candidate list may indicate a list in which motion information is stored. Also, the merge candidate list may be created before the merge mode is performed. The motion information stored in the merge candidate list includes motion information of neighboring blocks adjacent to the encoding/decoding object block, motion information of blocks collocated with the encoding/decoding object block in the reference image, and motion already existing in the merge candidate list. It may be at least one of new motion information generated by a combination of pieces of information and a zero merge candidate. Here, motion information of neighboring blocks adjacent to the encoding/decoding target block is a spatial merge candidate, and motion information of blocks collocated with the encoding/decoding target block in the reference image is a temporal merge candidate. ) can be referred to as

The skip mode may be a mode in which motion information of neighboring blocks is applied to an encoding/decoding target block as it is. A skip mode may be one of modes used for inter prediction. When the skip mode is used, the encoding apparatus 100 may entropy-encode information on which block motion information is to be used as motion information of an encoding target block and transmit the information to the decoding apparatus 200 through a bitstream. The encoding device 100 may not transmit other information to the decoding device 200. For example, the other information may be syntax element information. Syntax element information may include at least one of motion vector difference information, a coded block flag, and a transform coefficient level.

The residual signal generated after intra- or inter-prediction may be converted into a frequency domain through a conversion process as part of a quantization process. The primary transform performed at this time can use various DCT and DST kernels in addition to DCT type 2 (DCT-II), and these transform kernels perform one-dimensional transform (1D transform) on the residual signal in the horizontal and/or vertical directions. Transformations may be performed by separate transforms performed separately, or transforms may be performed by 2D non-separable transforms.

As an example, DCT and DST types used for conversion can adaptively use DCT-V, DCT-VIII, DST-I, and DST-VII in addition to DCT-II as shown in the table below for 1D conversion. For example, As shown in the examples of Tables 1 to 2, a DCT or DST type used for transformation can be derived by constructing a transform set.

conversion set conversion 0 DST_VII, DCT-VIII One DST-VII, DST-I 2 DST-VII, DCT-V

conversion set conversion 0 DST_VII, DCT-VIII, DST-I One DST-VII, DST-I, DCT-VIII 2 DST-VII, DCT-V, DST-I

For example, after defining different transform sets in the horizontal or vertical direction according to the intra prediction mode as shown in FIG. 8, the encoder/decoder determines the intra prediction mode of the current encoding/decoding target block Transformation and/or inverse transformation may be performed using a transformation included in a corresponding transformation set. In this case, the transform set may be defined according to the same rules in the encoder/decoder instead of entropy encoding/decoding. In this case, entropy encoding/decoding may be performed indicating which transform is used among transforms belonging to the corresponding transform set. For example, if the size of the block is 64x64 or less, a total of 3 transformation sets are configured according to the intra-prediction mode as shown in the example in Figure 2, and each of the 3 transformation sets is used for horizontal transformation and vertical transformation. Encoding efficiency can be improved by combining and performing a total of 9 multi-transformation methods and then encoding/decoding the residual signal using the optimal transformation method. In this case, truncated unary binarization may be used to entropy-encode/decode information on which of the three transforms belonging to one transform set is used. In this case, information indicating which transform among transforms belonging to the transform set is used for at least one of the vertical transform and the horizontal transform may be entropy encoded/decoded.

After the aforementioned primary transform is completed, the encoder may perform a secondary transform to increase energy concentration for transformed coefficients, as shown in the example of FIG. 9 . The secondary transformation may also perform a separate transformation in which one-dimensional transformation is performed in the horizontal and/or vertical directions, respectively, or a two-dimensional non-separate transformation may be performed, and the used transformation information is transmitted or It can be implicitly induced in the encoder/decoder according to the encoding information. For example, a transform set for a secondary transform may be defined like a primary transform, and the transform set may be defined according to the same rules in an encoder/decoder instead of entropy encoding/decoding. In this case, information indicating which transform is used among transforms belonging to the corresponding transform set may be transmitted, and may be applied to at least one or more of residual signals through intra- or inter-prediction.

At least one of the number or type of transform candidates is different for each transform set, and at least one of the number or type of transform candidates is the location, size, division type, prediction mode (intra/inter mode) of the block (CU, PU, TU, etc.) ) or at least one of directionality/non-directionality of the intra-prediction mode may be variably determined.

The decoder may perform a secondary inverse transform depending on whether or not a secondary inverse transform is performed, and may perform a primary inverse transform on a result of performing the secondary inverse transform depending on whether or not a primary inverse transform is performed.

The above-mentioned primary transformation and secondary transformation may be applied to at least one signal component among luminance/chrominance components or may be applied according to the size/shape of an arbitrary coding block, and whether or not they are used in an arbitrary coding block and the primary transformation used. The index indicating the /secondary transformation may be entropy-encoded/decoded or implicitly derived by the encoder/decoder according to at least one of the current/surrounding encoding information.

The residual signal generated after intra or inter-prediction is subjected to a quantization process after completing the first and/or second transformation, and then the quantized transformation coefficient undergoes an entropy encoding process. At this time, the quantized transformation coefficient is shown in FIG. Similarly, scanning may be performed in diagonal, vertical, and horizontal directions based on at least one of an intra prediction mode and a minimum block size/shape.

In addition, entropy-decoded quantized transform coefficients may be inverse scanned and arranged in a block form, and at least one of inverse quantization and inverse transform may be performed on the corresponding block. At this time, at least one of a diagonal scan, a horizontal scan, and a vertical scan may be performed as an inverse scanning method.

For example, when the size of the current coding block is 8x8, the residual signal for the 8x8 block is obtained by the three scanning order methods shown in FIG. Entropy encoding may be performed while scanning transform coefficients quantized according to at least one of In addition, entropy decoding may be performed while inversely scanning the quantized transform coefficient. The inverse scanned quantized transform coefficient becomes a transform coefficient after inverse quantization, and at least one of a second order inverse transform and a first order inverse transform is performed to generate a reconstructed residual signal.

In the video encoding process, one block may be divided as shown in FIG. 11, and an indicator corresponding to division information may be signaled. In this case, the split information may be at least one of a split flag (split_flag), a quad/binary tree flag (QB_flag), a quadtree split flag (quadtree_flag), a binary tree split flag (binarytree_flag), and a binary tree split type flag (Btype_flag). there is. Here, split_flag is a flag indicating whether the block is split, QB_flag is a flag indicating whether the block is split in the form of a quad tree or a binary tree, quadtree_flag is a flag indicating whether the block is split in the form of a quad tree, binarytree_flag may be a flag indicating whether a block is partitioned in a binary tree format, and Btype_flag may be a flag indicating vertical or horizontal partitioning when a block is partitioned in a binary tree format.

If the split flag is 1, it can indicate that it is split, and if 0, it is not split. In the case of the quad/binary tree flag, if it is 0, it can indicate quad tree split, and if it is 1, it can indicate binary tree split. If , it can represent a quadtree partition. In the case of the binary tree splitting type flag, 0 indicates horizontal splitting, 1 indicates vertical splitting, and conversely, 0 indicates vertical splitting and 1 indicates horizontal splitting.

For example, the division information of FIG. 11 can be derived by signaling at least one of quadtree_flag, binarytree_flag, and Btype_flag as shown in Table 3 below.

quadtree_flag One 0 One 0 0 0 0 0 0 binarytree_flag One 0 0 One 0 0 0 0 0 One One 0 0 0 0 Btype_flag One 0 0 One

For example, the split information for FIG. 11 can be derived by signaling at least one of split_flag, QB_flag, and Btype_flag as shown in Table 2 below.

split_flag One One 0 0 One One 0 0 0 0 0 One One 0 0 0 0 QB_flag 0 One 0 One One Btype_flag One 0 0 One

According to the size/shape of the block, the partitioning method may be partitioned only in a quad tree or in a binary tree. In this case, the split_flag may mean a flag indicating whether to split a quad tree or a binary tree. The size/shape of the block may be derived according to depth information of the block, and the depth information may be signaled.

When the size of the block falls within a predetermined range, partitioning may be possible only with a quad tree. Here, the predetermined range may be defined as at least one of a maximum block size and a minimum block size that can be partitioned with only a quad tree. Information indicating the size of the maximum/minimum block for which the quadtree partition is allowed may be signaled through a bitstream, and the corresponding information may be signaled in units of at least one of a sequence, a picture parameter, or a slice (segment). there is. Alternatively, the size of the maximum/minimum block may be a fixed size pre-set in the encoder/decoder. For example, when the size of the block corresponds to 256x256 to 64x64, partitioning may be possible only with a quad tree. In this case, the split_flag may be a flag indicating whether to split a quad tree.

When the size of the block falls within a predetermined range, partitioning may be possible only with a binary tree. Here, the predetermined range may be defined as at least one of a maximum block size and a minimum block size that can be partitioned using only the binary tree. Information indicating the size of the maximum/minimum block for which the binary tree partitioning is allowed may be signaled through a bitstream, and the corresponding information may be signaled in units of at least one of a sequence, a picture parameter, or a slice (segment). there is. Alternatively, the size of the maximum/minimum block may be a fixed size pre-set in the encoder/decoder. For example, when the size of the block corresponds to 16x16 to 8x8, partitioning may be possible only with a binary tree. In this case, the split_flag may be a flag indicating whether to split the binary tree.

After the one block is split into a binary tree, when the split block is further split, it can be split only into a binary tree.

When the horizontal or vertical size of the divided block is such that it cannot be further divided, the one or more indicators may not be signaled.

In addition to binary tree partitioning based on the quad tree, after binary tree partitioning, quad tree-based partitioning may be possible.

When a block is divided based on a quad tree and/or a binary tree, a block corresponding to a leaf node according to a final partition result of the block may be set as one encoding/decoding unit. That is, when a block having an arbitrary size or shape is not further divided, encoding/decoding may be performed on the corresponding block. For example, for a block having an arbitrary size and shape corresponding to a binary leaf node generated by quadtree and/or binary tree splitting, prediction (eg, inter-prediction or intra-prediction) and transformation An encoding/decoding process such as may be performed.

12 is a diagram exemplified to explain encoding/decoding units according to block division types. In the example shown in FIG. 12 , solid lines are for dividing blocks generated by quad tree partitioning, and dotted lines are for distinguishing blocks generated by binary tree partitioning. As in the example shown in FIG. 12, when it is assumed that the structure of the coding block is determined, a node finally divided through a real and a dotted line may be defined as a binary leaf node. A block corresponding to a binary leaf node is encoded/decoded in the size or shape of the block corresponding to the corresponding leaf node (eg, intra-prediction or inter-prediction, 1st transform, 2nd transform, quantization or entropy encoding/decoding, etc.) may be performed.

For convenience of description, in an embodiment to be described later, a partitioning form of a block based on a quad tree and/or a binary tree will be defined as a block structure.

In the encoding/decoding process, the block structure for each color component may be the same or the block structure for each color component may be different. For example, the block structure may be the same for luminance and chrominance components, or may be different for luminance and chrominance components, according to arbitrary encoding parameter conditions. Here, that the block structure of the luminance component and the chrominance component are the same may mean that the chrominance component inherits the block structure information determined for the luminance component or the luminance component inherits the block structure determined for the chrominance component. For example, luminance and chrominance signals may have different block structures or the same block structure in an intra frame or an intra slice according to a currently encoded/decoded picture or slice type. At this time, whether to set the same or different block structures for the luminance and chrominance components constituting the picture in the picture or the slice in the picture, after obtaining the rate-distortion cost function according to each block structure , can be determined through an encoding process for selecting a block structure with a minimum cost function.

The encoding device may entropy-encode information indicating whether to use the same block structure for each color component and transmit it to a decoding device. At this time, the information is a sequence level (eg, Sequence Parameter Set, SPS), a picture level (eg, Picture Parameter Set, PPS), a slice header, a maximum coding unit (LCT or CTU), or a coding unit (or coding block) may be encoded in at least one of them.

For example, encoding parameter information indicating whether block structures for each color component are the same for an intra-picture, intra-screen slice, inter-picture picture, or inter-screen slice may be transmitted through SPS or PPS.

Alternatively, encoding parameter information indicating whether block structures for each color component are the same for slices within a picture or slices between pictures may be transmitted through a slice header.

Alternatively, coding parameter information indicating whether the largest coding unit or coding units have the same block structure for each color component may be transmitted in units of the largest coding unit or coding units.

When an encoding/decoding object block satisfies a predetermined condition, block division may not be allowed for the encoding/decoding object block. Accordingly, encoding/decoding of block division information may be omitted for a block that satisfies a predetermined condition. Here, the predetermined condition is related to at least one of the size of the block, the shape of the block, or the splitting depth of the block, indicating the size, shape, or depth of a block in which quadtree and/or binary tree splitting is allowed or not allowed. can The size or shape of a block may be a reference value indicating the size or shape of a block in which quad tree and/or binary tree partitioning is allowed or not allowed, and block depth is a block size in which quad tree and/or binary tree partitioning is allowed or not allowed. Block depth threshold may be indicated. The block depth may be a variable that increases by 1 as quadtree and/or binary tree partitioning is performed.

The block partitioning information may include information indicating whether a block is split (eg, split_flag), information indicating whether a quad tree is split (eg, Quadtree_flag or QB_flag), information indicating whether a binary tree is split (eg, Binarytree_flag or QB_flag), or binary tree partitioning It may include at least one of type information (eg, Btype_flag).

For example, if it is assumed that a predetermined condition indicates that the block size is less than or equal to a reference value and binary tree partitioning is not allowed for a block that satisfies the predetermined condition, for a block having a size less than or equal to the reference value, information related to binary tree partitioning ( For example, encoding/decoding of at least one of a quad/binary tree flag (QB_flag), a binary tree partitioning flag (binaraytree_flag), or a binary tree partitioning type flag (Btype_flag) may be omitted. If encoding/decoding of the quad/binary tree flag (QB_flag) is omitted, the split flag (split_flag) may be used to indicate whether a block is quad-tree split.

It is not limited to the described example, and it may be configured not to allow quad tree splitting for a block that satisfies a predetermined condition. In this case, encoding/decoding of information related to quad tree splitting (eg, a quad/binary tree flag (QB_flag) or a quadtree split flag (quadtree_flag)) may be omitted for a block that satisfies a predetermined condition. If encoding/decoding for the quad/binary tree flag (QB_flag) is omitted, the split flag (split_flag) may be used to indicate whether a block is binary tree split.

As another example, any type of division may not be allowed for a block that satisfies a predetermined condition. In this case, no partition information may be encoded/decoded for a block that satisfies a predetermined condition.

Referring to the drawings, a process of determining whether to omit encoding/decoding of partition information will be described in more detail.

13 is a flowchart illustrating a process of determining whether to decode information related to binary tree partitioning. For convenience of explanation, in this embodiment, it is assumed that binary tree-based partitioning is not allowed for a block that satisfies a predetermined condition.

First, information related to a predetermined condition may be obtained (S1301). Here, the information related to the predetermined condition may include at least one of the block size, shape, and division depth. Based on the information related to the predetermined condition, the predetermined condition is whether the size of the block is greater than or equal to a threshold value, whether the size of the block is less than or equal to the threshold value, whether the shape of the block is a preset shape, and whether the depth of the block is greater than or equal to the threshold value, based on information related to the predetermined condition. , or whether the block depth is less than or equal to a threshold value.

Information related to a predetermined condition may be predefined in an encoder and a decoder. Here, the information related to the predetermined condition may indicate at least one of a size of a block, a shape of a block, or a depth of a block defining the predetermined condition. For example, the size/shape or split depth of a block in which encoding/decoding of split information is skipped may have a fixed value predefined in an encoder and a decoder. Alternatively, information related to a predetermined condition may be variably determined by an encoding parameter indicating a size/shape of a block to be encoded/decoded or a division depth of the block.

As another example, information related to a predetermined condition may be encoded/decoded in units of a sequence level, a picture level, a slice header, or a predetermined coding region. At this time, the predetermined coding region has a size/shape smaller than that of the currently encoded/decoded picture or slice, and is included in the largest coding unit (LCU or CTU) or a block of any size or shape included in the largest coding unit (e.g., maximum A block generated by dividing the coding unit into a quad tree), and the like. Information related to a predetermined condition may be expressed in the form of the maximum size of a block and/or the minimum size of a block, or the maximum depth of a block and/or the minimum size of a block.

The encoder compares the rate-distortion between the result of quad-tree and binary-tree-based encoding and the result of quad-tree-based encoding, determines the block structure, and according to the determined block structure, Information related to a predetermined condition may be encoded in consideration of the size, shape, or depth of a block on which binary tree partitioning is no longer performed. Also, the decoder may decode information related to a predetermined condition in which binary tree splitting is not permitted from the bitstream, and determine whether the current block satisfies the predetermined condition based on the decoded information.

The decoder may determine whether the current block satisfies a predetermined condition (S1302). As a result of the determination, when the current block satisfies a predetermined condition, decoding of information related to binary tree partitioning of the current block may be omitted.

On the other hand, if the current block does not satisfy a predetermined condition, information related to binary tree partitioning of the current block may be decoded according to whether the current block is quad-tree partitioned (S1303). For example, if quad tree partitioning is not performed on the current block, information related to binary tree partitioning of the current block may be decoded.

That is, it is possible to determine whether to encode/decode block division information for the current block by comparing whether the size, shape, or depth of the current block corresponds to the size, shape, or depth of the block according to a predetermined condition.

As another example, according to an embodiment of the present invention, information indicating whether block division is allowed for a block having an arbitrary size, arbitrary shape, or arbitrary depth may be encoded/decoded. Here, the information indicating whether block splitting is allowed may include information indicating whether quadtree splitting exists (eg, NoPresent_Quadtree_flag) or information indicating whether binary tree splitting exists (eg, NoPresent_Binarytree_flag).

If it is indicated that block splitting is not allowed for a block having an arbitrary size, shape, or depth, block splitting may not be permitted for the block as well as sub-blocks. Here, the lower block may include at least one of a block having a smaller size than the corresponding block, a block having the same shape as the corresponding block, a block having a greater division depth than the corresponding block, or a lower node block of the corresponding block.

For example, when information indicating whether binary tree partitioning exists for a block having an arbitrary size/shape is signaled, and the information indicates that there is no binary tree partitioning, not only the block, but also the size/shape smaller than the block For a block having a shape, information related to binary tree partitioning (eg, information indicating whether binary tree partitioning is performed (eg, quad/binary tree flag (QB_flag), binary tree partitioning flag (binaraytree_flag), or binary tree partitioning type flag (Btype_flag)) ), encoding/decoding of at least one) may be omitted.

It is not limited to the described example, and it is also possible to signal information indicating whether a quad tree partition exists or a binary tree partition type flag exists for a block having an arbitrary size/shape.

Information indicating whether block division is permitted may be transmitted for each predetermined coding region. At this time, the predetermined coding region has a size/shape smaller than that of the currently encoded/decoded picture or slice, and is included in the largest coding unit (LCU or CTU) or a block of any size or shape included in the largest coding unit (e.g., maximum A block generated by dividing the coding unit into a quad tree), and the like. The encoder determines the block structure by comparing the rate-distortion between the result of quad-tree and binary tree-based encoding and the result of performing quad-tree-based encoding on blocks of arbitrary size / shape , it is possible to determine whether to encode information indicating whether binary tree partitioning is allowed or not, according to the determined block structure.

Information indicating whether block division is allowed may be hierarchically encoded/decoded. For example, when information signaled for an upper block indicates that block splitting is allowed, information indicating whether block splitting is allowed again for a lower block generated by splitting the upper block may be encoded/decoded.

As another example, information about the size, shape, or depth of a block in which information indicating whether block division is allowed may be encoded/decoded at a higher level. For example, information on block size, shape, or depth may be transmitted through at least one of a sequence level, a picture level, and a slice header. In this case, information indicating whether block division is allowed may be signaled only for a block corresponding to a block size, shape, or depth signaled through a higher level or an upper block thereof.

14 is a flowchart illustrating a process of determining whether to decode information related to binary tree partitioning. For convenience of explanation, in this embodiment, it is assumed that information on whether binary tree partitioning is allowed is signaled only for the current block.

First, it is possible to decode information indicating whether to split the binary tree for the current block (S1401).

When the information indicates that binary tree splitting is not allowed (S1402), decoding of binary tree splitting information for the current block can be omitted. In addition, binary tree partitioning information may not be decoded for subblocks generated by quadtree partitioning of the current block.

On the other hand, if the information indicates that binary tree partitioning is allowed (S1402), information related to binary tree partitioning may be decoded according to whether or not the current block is quadtree partitioned (S1403). For example, if quad tree partitioning is not performed on the current block, information related to binary tree partitioning of the current block may be decoded. In addition, information related to binary tree partitioning may be decoded according to whether the lower block is quad-tree partitioned or not, for a sub-block generated by quad-tree or binary-tree partitioning of the current block.

15 to 17 are diagrams for explaining an example of a case in which binary tree partitioning is no longer performed on blocks having a predetermined size or less.

As in the example shown in FIG. 15, it is assumed that the size / shape of the maximum coding unit is 128x128 and only quad tree division exists without binary tree division in the maximum coding unit through rate-distortion optimization performed by the encoding device do.

If information indicating that binary tree partitioning is not performed for a block of a predetermined size is not encoded/decoded, as in the example shown in FIG. information must be encoded/decoded.

However, when encoding/decoding information indicating that binary tree splitting is not performed on blocks smaller than 128x128 in size, as in the example shown in FIG. There is no need to encode/decode information about Accordingly, the amount of information to be encoded is reduced, and encoding/decoding efficiency can be increased.

As described above with reference to FIG. 13 , the encoder may encode and transmit information about the size (eg, information indicating 128×128), shape, or depth of a block in which binary tree partitioning is not allowed to the decoding device. The decoding apparatus may decode information about the size of a block on which binary tree partitioning is not performed from the bitstream, and may no longer decode information related to binary tree partitioning for a block equal to or smaller than the size indicated by the decoded information.

As another example, as described above with reference to FIG. 14 , the encoding device may encode information indicating that binary tree splitting is not allowed for a block of an arbitrary size on which binary tree splitting is not performed and may transmit the encoded information to the decoding device. Here, the information may be a 1-bit flag (eg, NoPresent_BinaryTree_flag), but is not limited thereto. In the example shown in FIG. 17 , NoPresent_BinaryTree_flag is signaled for a 128×128 block.

16 and 17 show that the value of the flag is set to 1 when quad tree or binary tree partitioning is performed, and the value of the flag is set to 0 otherwise. However, the opposite setting is also possible.

An embodiment related to not allowing block division may be applied to a luminance component and a chrominance component. At this time, information indicating that block division is not permitted (eg, information indicating block size, shape, or size in which block division is not permitted, or information indicating whether block division is permitted) is provided for the luminance component and the chrominance component. It may be commonly applied, or may be individually signaled for the luminance component and the chrominance component. In the case of entropy encoding/decoding the information, a truncated rice binarization method, a K-th order Exp_Golomb binarization method, and a restricted K-th order Exp_Golomb binarization method , at least one entropy encoding method among a fixed-length binarization method, a unary binarization method, and a truncated unary binarization method may be used. In addition, after binarizing the information, the information may be finally encoded/decoded using CABAC (ae(v)).

Next, the residual signal conversion and scanning of the current block will be described.

In performing encoding/decoding of the residual signal of the current block, at least one of the encoding information of the residual signal of the current block is transmitted through the encoding information of the residual signal of the encoded/decoded blocks around the current block to the encoder/decoder. It can be derived implicitly in the decryptor. Here, the encoding information for the residual signal may include information related to a transform technique of the residual signal (eg, a transform technique used for the primary transform and the secondary transform), information for scanning quantized transform coefficients, and the like. . Here, the quantized transform coefficient may mean that transform (eg, primary transform and secondary transform) and quantization are performed on the residual signal generated after intra-prediction.

Specifically, if the current block is coded through intra prediction, encoding information for the current block may be derived from adjacent blocks around the current block based on an intra prediction mode of the current block. On the other hand, if the current block is encoded through inter-prediction, encoding information on the current block may be derived from adjacent blocks around the current block based on motion-related information of the current block. Hereinafter, referring to FIGS. 18 and 19, when the current block is coded through intra prediction and when the current block is coded through inter prediction, encoding information on a residual signal of the current block is obtained from neighboring blocks. Let's take a closer look at what induces.

18 is a flowchart illustrating a process of determining whether to derive encoding information for a residual signal of a current block from a neighboring block when the current block is coded by intra prediction.

First, it may be determined whether a neighboring block encoded in the same intra prediction mode as the intra prediction mode of the current block exists (S1801). Here, neighboring blocks of the current block may refer to blocks that are included in the same picture as the current block (ie, the current picture) and have been encoded/decoded prior to the current block. For example, a neighboring block may include a block adjacent to the current block among blocks encoded/decoded prior to the current block. Here, the block adjacent to the current block is a block adjacent to the boundary of the current block (eg, a left boundary or an upper boundary) and a block adjacent to a corner (eg, an upper left corner, an upper right corner, or a lower left corner) of the current block. may contain at least one.

If a neighboring block encoded in the same intra prediction mode as the intra prediction mode of the current block exists, encoding information on a residual signal of the corresponding neighboring block may be derived as encoding information of the current block (S1802). Specifically, at least one of primary transform, secondary transform, or scanning information of the current block may be derived from a neighboring block having the same intra-prediction mode as the current block.

For example, if the intra-prediction mode of the current block is the same as that of an adjacent block of the current block and the corresponding adjacent block skips the primary transform, the residual signal of the current coding block may also skip the primary transform. . When the primary transform of the current block is skipped, the secondary transform of the current block may also be skipped.

Alternatively, when the intra prediction mode of the current block is the same as that of neighboring blocks of the current block, the first transform applied to the neighboring blocks having the same intra prediction mode as the current block in the horizontal and vertical directions of the current block can be set the same as Accordingly, encoding/decoding of encoding information (eg, transform information (or transform index) for the horizontal and vertical directions used for the primary transform) required for primary transform of the residual signal of the current block can be omitted.

For example, when the intra-prediction mode of the current block is determined to be number 23 (mode 23) and the intra-prediction mode of at least one of neighboring blocks adjacent to the current block is also determined to be number 23 (mode 23), the intra-prediction mode The primary transformation applied to the residual signal of the neighboring block number 23 may be used as the primary transformation of the residual signal of the current block. For example, if the residual signal of the neighboring block having the same intra-prediction mode as the current block is first transformed by DCT-V in the horizontal direction and DST-VII in the vertical direction, the first transformation of the residual signal of the current block is also The direction may be performed by DCT-V and the vertical direction by DST-VII.

As another example, when the intra-prediction mode of the current block is the same as that of neighboring blocks of the current block, the secondary transform of the current block may be set to be the same as the secondary transform applied to the neighboring blocks having the same intra-prediction mode as the current block. can Accordingly, encoding/decoding of encoding information (eg, transform information (or transform index) for the secondary transform) required for secondary transform of the residual signal of the current block may be omitted.

For example, when the intra-prediction mode of the current block is determined to be number 35 (mode 35) and the intra-prediction mode of at least one of neighboring blocks adjacent to the current block is also determined to be number 35 (mode 35), the intra-prediction mode The secondary transformation applied to the residual signal of the neighboring block number 35 may be used as the secondary transformation of the residual signal of the current block.

As another example, when the intra-prediction mode of the current block is the same as that of neighboring blocks of the current block, the scanning order of the current block may be set to be the same as the scanning order of neighboring blocks having the same intra-prediction mode as the current block. Accordingly, encoding information required for scanning quantized transformed coefficients for the residual signal of the current block (eg, diagonal, horizontal, vertical, meaning a scanning order) Encoding/decoding of at least one scanning order index of the vertical direction may be omitted.

In addition to the above example, at least two of the primary transform, secondary transform, and scanning order of neighboring blocks having the same intra-prediction mode as the current block may be derived as encoding information of the current block.

For example, the primary transform and secondary transform of neighboring blocks having the same intra-prediction mode as the current block are applied to the current block, or the primary transform and scanning order of neighboring blocks or the secondary transform and scanning order of neighboring blocks are changed. Applies to the current block. Alternatively, it is also possible to apply all of the primary transform, secondary transform, and scanning order of neighboring blocks having the same intra-prediction mode as the current block to the current block.

When there are a plurality of neighboring blocks having the same intra-prediction mode as the current block, encoding information of the current block may be derived based on priorities among neighboring blocks. For example, if the left neighboring block and the upper neighboring block of the current block have the same intra prediction mode as the current block, and the priority of the left neighboring block is higher than that of the upper neighboring block, the encoding information of the current block is It can be derived based on encoding information of a block.

As another example, when there are a plurality of neighboring blocks having the same intra-prediction mode as the current block, information for identifying neighboring blocks used to derive encoding information of the current block may be signaled through a bitstream. there is. In this case, encoding information for a residual signal of the current block may be derived from a neighboring block indicated by information (eg, a neighboring block index) for identifying the neighboring block.

If there is no neighboring block having the same intra-prediction mode as the current block, entropy encoding/decoding of encoding information on the residual signal of the current block may be performed (S1803). For example, when there is no neighboring block having the same intra-prediction mode as the current block, transform information (or transform index) for the primary transform of the current block, transform information (or transform index) for the secondary transform, or At least one of scanning order information (or scanning index) may be entropy encoded/decoded.

In the above-described embodiment, it has been described that the encoding information for the residual signal of the current block is derived from the neighboring block on the condition that the intra prediction mode of the current block and the intra prediction mode of the neighboring block are the same. As another example, it is also possible to derive second encoding information for the residual signal of the current block from a neighboring block having the same first encoding information for the residual signal as the current block. Here, the first encoding information and the second encoding information may include at least one of primary transformation information, secondary transformation information, and a scanning order.

For example, if there is at least one neighboring block using the same primary transform as the primary transform determined for the current block, the secondary transform of the current block is a secondary transform applied to neighboring blocks using the same primary transform as the current block. Transformation can be set. In this case, encoding/decoding of encoding information necessary for secondary transforming the residual signal for the current block may be omitted. For example, it is assumed that the primary transform for the residual signal of the current block is determined to be DCT-V in the horizontal direction and DST-VII in the vertical direction. If the primary transform of one or more of the blocks adjacent to the current block is determined to be DCT-V in the horizontal direction and DST-VII in the vertical direction, the secondary transform of the adjacent block to which the same primary transform as that of the current block is applied is applied. It can be applied as a secondary transformation of blocks.

Alternatively, the scanning order of neighboring blocks using the same primary transform as that of the current block may be applied as the scanning order of the current block. Alternatively, it is also possible to apply the secondary transform and scanning order of neighboring blocks using the same primary transform as the primary transform of the current block to the current block.

In the above-described embodiment, it has been described that at least one of the secondary transform or scanning order of the current block is derived from the neighboring block using the same primary transform as the current block, but the neighboring blocks using the same secondary transform as the current block. Deriving at least one of the primary transform or scanning order of the current block from a block, or deriving at least one of the primary transform or secondary transform of the current block from neighboring blocks using the same scanning order as the current block possible.

The second encoding information of the current block may be derived from a neighboring block having the same intra-prediction mode and first encoding information as the current block.

For example, when there exists at least one neighboring block using the same intra prediction mode and primary transform as the intra prediction mode determined for the current block and the primary transform determined for the current block, the secondary transform of the current block is It is the same as the intra-prediction mode of the current block and can be set to a secondary transform applied to neighboring blocks using the same primary transform as the current block. In this case, encoding/decoding of encoding information necessary for secondary transforming the residual signal for the current block may be omitted.

Alternatively, the scanning order of neighboring blocks having the same intra-prediction mode and primary transform as the current block may be applied as the scanning order of the current block. Alternatively, the secondary transform and scanning order of neighboring blocks having the same intra-prediction mode and primary transform as the current block may be applied to the current block.

In the above-described embodiment, it has been described that at least one of a secondary transform or a scanning order of the current block is derived from a neighboring block having the same intra-prediction mode as the current block and using the same primary transform as the current block. In addition, at least one of the primary transform or scanning order of the current block is derived from a neighboring block having the same intra-prediction mode as the current block and using the same secondary transform as the current block, or the same picture as the current block. It is also possible to derive at least one of a primary transform or a secondary transform of the current block from a neighboring block having an intra prediction mode and using the same scanning order as the current block.

19 is a flowchart illustrating a process of determining whether to derive encoding information for a residual signal of a current block from a neighboring block when the current block is coded by inter-prediction.

First, it may be determined whether the inter-prediction mode of the current block is the merge mode (S1901). When the inter-prediction mode of the current block is the merge mode, neighboring blocks to be merged with the current block may be determined in order to derive motion information of the current block (S1902). For example, a neighboring block to be merged with the current block may be determined by a merge index indicating a neighboring block to be merged with the current block from a merge candidate list. Here, the neighboring blocks of the current block may include neighboring blocks temporally adjacent to the current block as well as neighboring blocks spatially adjacent to the current block.

When the neighboring block to be merged with the current block is determined, encoding information for the residual signal of the neighboring block to be merged with the current block may be derived as encoding information for the residual signal of the current block (S1903). For example, at least one of primary transform, secondary transform, or scanning order of the current block may be set to be identical to at least one of primary transform, secondary transform, or scanning order of neighboring blocks to be merged with the current block.

When the inter-prediction mode of the current block is not the merge mode, it may be determined whether a neighboring block having motion information identical to that of the current block exists among neighboring blocks of the current block (S1904). Here, the motion information may include at least one of a motion vector, a reference picture index, and a reference picture direction.

If a neighboring block having the same motion information as that of the current block exists, encoding information for a residual signal of the neighboring block having the same motion information as that of the current block may be derived as encoding information for the residual signal of the current block. Yes (S1905). For example, at least one of the primary transformation, secondary transformation, or scanning order of the current block is the primary transformation of the neighboring block, wherein at least one of the motion vector, reference picture index, and reference picture direction of the current block is the same as the current block; It may be set equal to at least one of secondary transformation or scanning order.

If there is no neighboring block having the same motion information as the current block, entropy encoding/decoding of encoding information on the residual signal of the current block may be performed (S1906). For example, when there is no neighboring block having the same motion information as the current block, transform information (or transform index) for the first transform of the current block, transform information (or transform index) for the second transform, or scanning order of the current block At least one of the information (or scanning index) for may be entropy encoded/decoded.

In the example shown in FIG. 19 , a neighboring block from which encoding information for a residual signal of the current block is to be derived is adaptively determined according to whether the inter prediction mode of the current block is the merge mode. Unlike the example shown in FIG. 19 , encoding information for a residual signal of the current block may be derived from neighboring blocks only when the inter prediction mode of the current block is the merge mode. Alternatively, it is also possible to derive encoding information of the current block from neighboring blocks having the same motion information as the current block, regardless of whether the inter prediction mode of the current block is the merge mode.

In the above-described embodiment, it has been described that the encoding information for the residual signal of the current block is derived from the neighboring blocks on the condition that the motion information of the current block and the motion information of the neighboring blocks are the same. As another example, it is also possible to derive second encoding information for the residual signal of the current block from a neighboring block having the same first encoding information for the motion information and the residual signal as the current block.

After obtaining the motion information of the current block as in the above-described embodiment, it is possible to derive encoding information of the current block from the neighboring blocks based on whether the motion information of the current block is the same as the motion information of the neighboring blocks. In addition, it is also possible to derive encoding information of the current block based on motion information of neighboring blocks without considering motion information of the current block.

The encoding information such as the above-described primary transformation, secondary transformation, or scanning order may include information indicating whether a predefined type (eg, a predefined transformation type or a predefined scanning type) is used or a predefined type. Encoding/decoding may be performed based on at least one of information indicating any one of the excluded residual types (eg, residual transformation type or residual scanning type).

For example, when a residual signal is generated through intra-prediction and/or inter-prediction, information indicating whether a predefined transform type is applied to the residual signal may be encoded. Here, the predefined transform type may be the most frequently used transform type (eg, DCT-II) for transforming the residual signal, but is not limited thereto. The information may be a 1-bit flag (eg, Transform Flag, TM flag). For example, when the TM flag is 0 (or 1), it means that a predefined transform type is applied to the residual signal, and when the TM flag is 1 (or 0), a predefined transform type is applied to the residual signal. It may mean that a conversion type other than the type is applied. Alternatively, the above information is configured with a flag of 2 bits or more to indicate whether or not a conversion type predefined for the primary conversion is used through the first bit, and a conversion predefined for the secondary conversion through the second bit. It can also indicate whether a type is used.

When the information indicates that a transform type other than a predefined transform type is applied to the residual signal, information for specifying one of the residual transform types may be encoded. Here, the residual transform type may represent transform types other than predefined transform types among transform types applicable to the residual signal. For example, when the predefined transform type is DCT-II, the residual transform type may include at least one of DCT-V, DCT-VIII, DST-I, and DST-VII. The information may be index information (TM idx) specifying any one of the residual transform types, and the index information may have an arbitrary positive integer. For example, TM idx 1 may indicate DCT-V, 2 may indicate DCT-VIII, 3 may indicate DST-I, and 4 may indicate DST-VII.

The index information may indicate a combination of transform types for horizontal and vertical directions of the residual signal. That is, the 1D transform type for the horizontal/vertical directions can be determined by one piece of index information. For example, when TM flag is 1 and TM idx is 1, a transform type combination mapped to TM idx 1 may be determined as a transform type for the horizontal and vertical directions of the current block. For example, if TM idx indicates DCT-V for the horizontal direction and DCT-VIII for the vertical direction, the DCT-V and DCT-VIII may be determined as the horizontal conversion type and the vertical conversion type of the current block, respectively. there is.

In determining the encoding parameter of the current block, at least one of information specifying whether a predefined type is used or any one of residual types may be derived from neighboring blocks of the current block. For example, at least one of information (TM flag) indicating whether a predefined transform type of the current block is applied or information (TM idx) for specifying one of residual transform types may be derived from a neighboring block of the current block. there is.

For example, at least one of TM flag and TM idx of the current block may be derived to have the same value as that of neighboring blocks of the current block.

Alternatively, when the TM flag of at least one of neighboring blocks of the current block is 1, encoding/decoding may be performed by implicitly assuming that the TM flag of the current block is 1. In this case, the TM idx for the current block may be explicitly transmitted through a bitstream or implicitly derived from neighboring blocks.

For example, any one of information (TM flag) indicating whether a predefined transform type for the current block is applied or residual transform type from neighboring blocks used in intra-prediction or inter-prediction of the current block. At least one of information (TM idx) for specifying can be derived.

For example, when the inter prediction mode of the current block is the merge mode, a merge candidate may be newly constructed in consideration of at least one of the TM flag and the TM idx. The newly constructed merge candidate list may include merge candidates having different values of at least one of TM flag and TM idx. For example, a merge candidate list may be configured such that a first merge candidate and a second merge candidate have the same motion information but different TM flags and/or TM idx. At least one of the TM flag or TM idx of the current block may be determined to be the same as the merge candidate indicated by the merge index (Merge_idx). Accordingly, not only motion information (motion vector, reference picture index, inter prediction direction indicator) of the current block, but also TM flag and/or TM idx can be coded/decoded based on the merge mode.

In this case, information indicating that the merge candidate list is newly constructed may be explicitly transmitted through a bitstream. The transmitted information may be a 1-bit flag, but is not limited thereto. Alternatively, when the TM flag of at least one neighboring block of the current block is 1, it may be implicitly recognized that the merge candidate list is newly constructed. Here, the neighboring block may be a block in which the TM flag first becomes 1 according to a predetermined neighboring block scanning order, or may be a block at a predefined position.

In the above-described embodiment, a method for deriving information (eg, TM flag and/or TM idx) for determining a transform type from neighboring blocks of the current block has been described. The described embodiment may be applied to at least one of determining a transform type for a primary transform or determining a transform type for a secondary transform of a current block. As an example, that is, conversion information for the first conversion (eg, TM flag (1 ^st TM flag) and / or TM idx (1 ^st TM idx)) or conversion information for the second conversion (eg, TM flag (2nd At least one of TM flag) or TM idx (2 ^nd TM idx)) may be derived from a neighboring block of the current block.

Also, apart from the merge candidate list generated based on motion information, a merge candidate list may be generated based on transform information on the current block. For example, a merge candidate list generated based on motion information of neighboring blocks is defined as a 'first merge candidate list', and a merge candidate list generated based on transformation information of neighboring blocks is referred to as a 'second merge candidate list'. When defined, the motion information of the current block is derived from the merge candidate specified by the first merge index in the first merge candidate list, while the transformation information of the current block is derived by the second merge index in the second merge candidate list. It can be derived from a specified merge candidate.

In addition to this, information (eg, scan flag and/or scan idx) for determining the scanning order of the current block may be derived from neighboring blocks of the current block. Here, the scan flag indicates whether the scanning order of the current block is the same as the predefined scanning order, and the scan idx may be information indicating one of the remaining scanning orders.

According to another embodiment of the present invention, the same encoding information may be applied to all blocks located within a signaling block in a currently encoded/decoded picture or slice. Here, the signaling block may mean a region having a small size for at least one of horizontal and vertical resolutions of the current picture or current slice. That is, a signaling block may be defined as a predetermined area having a size smaller than that of the current picture or current slice.

Information on a signaling block may be transmitted through at least one of a sequence unit, a picture unit, or a slice header. For example, at least one of the size, shape, or location of a signaling block may be transmitted through at least one of a sequence parameter set, a picture parameter set, and a slice header. Alternatively, information on the signaling block may be implicitly derived through encoding information of the current block or neighboring blocks adjacent to the current block. The signaling block may have a square or rectangular shape, but is not limited thereto.

Encoding information for a signaling block may be applied to all blocks included in the signaling block. For example, for all blocks included in the signaling block, at least one of a primary transform, a secondary transform, or a scanning order may be set identically. Encoding information applied to all blocks included in the signaling block may be transmitted through a bitstream. Alternatively, encoding information of a specific location block within a signaling block may be applied to all blocks included in the signaling block.

In the above-described embodiment, it has been described that all blocks included in the signaling block have the same encoding information. As another example, only blocks satisfying a predetermined condition among blocks included in a signaling block may be configured to have the same encoding information. Here, the predetermined condition may be defined by at least one of the size, shape, or depth of the block. For example, at least one of a primary transform, a secondary transform, or a scanning order may be set to be the same for blocks having a predetermined size or less (eg, blocks having a size of 4x4 or less) among all blocks included in the signaling block.

The above-described embodiments of obtaining encoding information of the current block may be applied to luminance and color difference components. In addition, information indicating that at least one of primary transform, secondary transform, or scanning has been performed on the residual signal of the current block may be encoded/decoded using at least one method of the above embodiments. In the case of entropy encoding/decoding the information, a truncated rice binarization method, a K-th order Exp_Golomb binarization method, and a restricted K-th order Exp_Golomb binarization method , at least one entropy encoding method among a fixed-length binarization method, a unary binarization method, and a truncated unary binarization method may be used. In addition, after binarizing the information, the information may be finally encoded/decoded using CABAC (ae(v)). Alternatively, it may be implicitly induced that encoding information of the current block is determined using at least one of the above embodiments according to the size and shape of the current block.

Next, encoding/decoding of motion vector information will be described in detail.

When the current block is encoded by inter-prediction, the encoder may transmit a motion vector difference (MVD) representing a difference between an encoded motion vector of the current block and a motion vector of the current block to the decoder. there is.

The decoder may derive a motion vector candidate of the current block from a motion vector for which neighboring encoding of the current block has been completed. Specifically, the decoder may derive a motion vector candidate from at least one or more temporal and/or spatial motion vectors of which decoding has been completed for the current block, and then construct a motion vector candidate list (MVP list).

The encoder may transmit information (eg, MVP list index) indicating information on a motion vector predictor used to derive a motion vector difference value among motion vector candidates included in the motion vector candidate list. Then, the decoding apparatus may determine a motion vector candidate indicated by the MVP list index as a motion vector predicted value, and derive a motion vector for the current block using the motion vector predicted value and the motion vector difference value.

Based on the above description, a method of encoding/decoding motion vector information of a current block according to the present invention will be described in detail.

20 is a flowchart illustrating a process of decoding a motion vector of a current block.

First, a spatial motion vector candidate for the current block can be derived (S2001). A spatial motion vector of the current block may be derived from a previously encoded/decoded block included in the same picture as the current block.

21 is a diagram for explaining an example of deriving a spatial motion vector candidate.

As in the example shown in FIG. 21, a block B1 adjacent to the top of the current block X, a block A1 adjacent to the left side of the current block, a block B0 adjacent to the upper right corner of the current block, and A spatial motion vector of the current block can be derived from the block B2 located at the upper left corner and the block A0 adjacent to the lower left corner of the current block. A spatial motion vector derived from neighboring blocks of the current block may be determined as a spatial motion vector candidate of the current block.

In this case, spatial motion vector candidates may be derived according to a predetermined order. For example, the spatial motion vector candidates may determine whether motion vectors exist in each block in the order of A0, A1, B0, B1, and B2. When there is a motion vector of a neighboring block, the motion vector of the neighboring block may be determined as a spatial motion vector candidate.

If the reference image of the neighboring block is different from the reference image of the current block, the motion of the neighboring block is performed using the distance between the current image and the reference image referred to by the neighboring block and the distance between the current image and the reference image referred to by the current block. A vector may be scaled with a motion vector, and the scaled motion vector may be determined as a spatial motion vector of the current block.

Next, a temporal motion vector candidate of the current block may be derived (S2002). A temporal motion vector of the current block may be derived from a reconstructed block in a co-located picture.

22 is a diagram for explaining an example of deriving a temporal motion vector candidate.

As in the example shown in FIG. 22, the outside of a co-located block (C) corresponding to the spatially same position as the current block (X) in a co-located picture of the current picture. A temporal motion vector candidate of the current block can be derived from a block at position H existing in , or a block at position C3 existing inside the corresponding block C. The temporal motion vector candidate may be sequentially derived from the block at the H position and the block at the C3 position. For example, when a motion vector can be derived from a block at position H, a temporal motion vector candidate can be derived from a block at position H. On the other hand, when a motion vector cannot be derived from a block at position H, a temporal motion vector candidate can be derived from a block at position C3. If the H position or C3 position block is coded by intra prediction, a temporal motion vector candidate of the current block cannot be derived.

22, the co-located picture indicated by the motion information obtained for the current block and the corresponding location block included in the co-located picture indicated by the motion information or the surroundings of the corresponding location block From the block, one or more temporal motion vector candidates may be derived for the current block. Here, the motion information may include at least one of a picture index indicating a corresponding position image and a motion vector indicating a corresponding position block in the corresponding position image. Motion information for specifying the location of the corresponding location image and the corresponding location block may be separately signaled for the current block.

Temporal motion vector candidates of the current block may be obtained in units of sub-blocks having a size smaller than that of the current block. For example, when the size of the current block is 8x8, temporal motion vector candidates may be obtained in units of subblocks smaller than the size of the current block, such as 2x2, 4x4, 8x4, and 4x8. The shape of the sub-block may have a square or rectangular shape. In addition, the size or shape of a sub-block may be a fixed one preset in an encoder/decoder or may be determined dependently on the size or shape of a current block.

Thereafter, a motion vector candidate list including at least one of a spatial motion vector candidate and a temporal motion vector candidate may be generated (S2003).

In this case, the motion vector candidate list may be configured to include at least one or more temporal motion vector candidates. For example, when the number of motion vector candidates that can be included in the motion vector candidate list is N (where N is a positive integer greater than 0), at least one motion vector candidate must be included in the motion vector candidate list. , a motion vector candidate list can be constructed. Even if up to N different spatial motion vector candidates can be derived in the process of deriving spatial motion vector candidates, at least one of the N spatial motion vector candidates is removed from the motion vector candidate list through an arbitrary similarity determination. can do. Accordingly, the temporal motion vector candidate may be included in the motion vector candidate list. Here, even if the spatial motion vectors have different values, the arbitrary similarity determination is performed by determining two or more spatial motion vectors through a maximum value, a minimum value, an average value, a median value, or an arbitrary sum of weights when the difference between the motion vectors is not large. may mean merging into one. The number of spatial motion vector candidates can be reduced through arbitrary similarity determination.

Alternatively, when N spatial motion vector candidates are included according to a predetermined priority in the motion vector candidate list, at least one or more of the spatial motion vector candidates may be removed from the motion vector candidate list in the reverse order of priority. That is, at least one or more may be removed from the motion vector candidate list starting from the spatial motion vector candidate of the lower order. Accordingly, the temporal motion vector candidate may be included in the motion vector candidate list.

Whether to remove the spatial motion vector candidate from the above-described motion vector candidate list may be determined according to whether the temporal motion vector candidate is used. Also, the number of spatial motion vector candidates to be removed from the motion vector candidate list may be determined according to the number of temporal motion vector candidates used for the current block or the number of temporal motion vector candidates available for the current block.

Alternatively, the temporal motion vector candidate may be included in the motion vector candidate list by further increasing the number of motion vector candidates that can be included in the motion vector candidate list (ie, increasing to N+1).

Thereafter, one of the motion vector candidates included in the motion vector candidate list may be determined as a motion vector prediction value of the current block (S2004). For example, decoding may determine a motion vector prediction value of the current block based on information specifying one of the motion vector candidates included in the motion vector candidate list (eg, MVP list index).

When the predicted motion vector of the current block is determined, the motion vector of the current block may be obtained using the motion vector difference value (S2005). The motion vector difference value may indicate a difference between a motion vector of the current block and a predicted motion vector of the current block. A motion vector difference value for the current block may be entropy encoded/decoded through a bitstream.

According to an embodiment of the present invention, in order to reduce the amount of information on the motion vector difference value, the motion vector difference value of the current block is encoded using motion vector difference values of reconstructed blocks encoded by inter-prediction around the current block. You may. For example, a second motion vector difference representing a difference between a motion vector difference representing a difference between a motion vector of the current block and a motion vector predicted value, and a motion vector difference representing a difference between motion vector differences of reconstructed blocks encoded by inter-prediction around the current block. A value can be coded for the current block.

23 is a diagram for explaining a second motion vector difference value.

It is assumed that the motion vector difference value (MVD) for the current block (Block 2) is (5, 5). In this case, a second motion vector difference value for the current block may be encoded using the motion vector difference value of the upper block (Block 1) located above the current block.

For example, assuming that the motion vector difference of the upper block is (5, 5), since the motion vector difference of the current block and the motion vector difference of the upper block are the same, the second motion vector difference of the current block is ( 0, 0) can be. If the second motion vector difference value (0, 0) is encoded instead of the motion vector difference value (5, 5), the amount of information used to encode the motion vector difference value for the current block can be reduced.

Alternatively, if there exists a block having the same motion vector difference value as the motion vector difference value of the current block, the motion vector difference value of the current block may be derived from neighboring blocks instead of transmitting the motion vector difference value of the current block. .

As in the above example, the information indicating the position of the neighboring block used to derive the second motion vector candidate of the current block or the position of the neighboring block having the same motion vector difference value as the current block is explicitly transmitted through a bitstream. It can be. For example, information (e.g., MVD index) used to derive a second motion vector candidate among neighboring blocks of the current block or to identify a neighboring block having the same motion vector candidate as the current block is transmitted to a decoder through a bitstream It can be.

As another example, information indicating the position of a neighboring block used to derive the second motion vector candidate of the current block or the position of a neighboring block having the same motion vector difference value as the current block is implicitly obtained by the encoder/decoder according to the same process. may be induced. For example, the motion vector difference value of neighboring blocks used as the motion vector predictor (MVP) of the current block may be used as a motion vector difference predictor (MVD predictor) for deriving the second motion vector difference value of the current block. .

When the current block is encoded by bidirectional prediction, information indicating whether motion vector difference values for reference picture list 0 (List 0) and reference picture list 1 (List 1) are the same may be encoded. Here, that the motion vector differences are the same may mean a case in which the signs and magnitudes of the motion vector differences are the same, or may mean a case in which the signs and magnitudes of the motion vector differential values are different but the magnitudes are the same. If the motion vector differences between reference picture list 0 and reference picture list 1 are the same, encoding/decoding of the motion vector difference between reference picture list 0 and reference picture list 1 can be omitted.

According to another embodiment of the present invention, all blocks located in a signaling block in a picture or slice to be currently encoded/decoded have one or more identical motion vector predictors in order to derive an optimal motion vector difference value (MVD). (MVP). Alternatively, according to another embodiment of the present invention, all blocks located in a signaling block in a currently encoded/decoded picture or slice have one or more identical motion vectors in order to derive an optimal second motion vector difference value. It may have a differential prediction value (MVD Predictor). In this case, a motion vector predictor or a motion vector differential predictor may be transmitted for each signaling block, or a motion vector predictor or motion vector differential predictor may be implicitly derived using encoding information of neighboring blocks around the signaling block. Here, the signaling block may mean a region having a small size for at least one of horizontal and vertical resolutions of the current picture or current slice. That is, a signaling block may be defined as a predetermined area having a size smaller than that of the current picture or current slice.

Information on a signaling block may be transmitted through at least one of a sequence unit, a picture unit, or a slice header. For example, at least one of the size, shape, or location of a signaling block may be transmitted through at least one of a sequence parameter set, a picture parameter set, and a slice header. Alternatively, information on the signaling block may be implicitly derived through encoding information of the current block or neighboring blocks adjacent to the current block. The signaling block may have a square or rectangular shape, but is not limited thereto.

The inter-screen encoding/decoding process may be performed for each of the luminance and color difference signals. For example, in the inter-screen encoding/decoding process, at least one method of acquiring an inter-prediction indicator, generating a motion vector candidate list, deriving a motion vector, and performing motion compensation may be applied differently to a luminance signal and a chrominance signal.

The inter-screen encoding/decoding process for the luminance and color difference signals may be performed in the same manner. For example, in the inter-screen encoding/decoding process applied to the luminance signal, at least one of an inter-prediction indicator, a motion vector candidate list, a motion vector candidate, a motion vector, and a reference image may be equally applied to the chrominance signal.

The above methods can be performed in the same way in the encoder and decoder. For example, in the inter-screen encoding/decoding process, at least one method of deriving a motion vector candidate list, deriving a motion vector candidate, deriving a motion vector, and motion compensation may be equally applied to an encoder and a decoder. In addition, the order of applying the above methods may be different between the encoder and the decoder.

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 block, and a 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. In addition, the above embodiments of the present invention can be applied only when the size is greater than the minimum size and less than the maximum size. That is, the above embodiments can 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 an encoding/decoding target block is 8x8 or larger. For example, the above embodiments can be applied only when the size of an encoding/decoding object block is 16x16 or larger. For example, the above embodiments can be applied only when the size of an encoding/decoding target block is 32x32 or larger. For example, the above embodiments can be applied only when the size of an encoding/decoding object block is 64x64 or larger. For example, the above embodiments can be applied only when the size of an encoding/decoding object block is 128x128 or larger. For example, the above embodiments can be applied only when the size of an encoding/decoding object block is 4x4. For example, the above embodiments can be applied only when the size of an encoding/decoding target block is 8x8 or less. For example, the above embodiments can be applied only when the size of an encoding/decoding object block is 16x16 or less. For example, the above embodiments can be applied only when the size of an encoding/decoding object block is greater than or equal to 8x8 and less than or equal to 16x16. For example, the above embodiments can be applied only when the size of an encoding/decoding target 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 a minimum layer and/or a maximum layer to which the embodiment is applicable, or may be defined as indicating a specific layer to which the embodiment is applied.

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 may be applied only when the temporal layer identifier of the current video is 0. 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.

As in the above embodiment of the present invention, the reference picture set used in the process of reference picture list construction and reference picture list modification is L0, L1, L2, L3. At least one or more reference image lists may be used.

According to the above embodiment of the present invention, one or more and up to N motion vectors of a block to be encoded/decoded may be used when calculating boundary strength in a deblocking filter. Here, N represents a positive integer greater than or equal to 1, and may be 2, 3, 4, and the like.

When predicting the motion vector, the motion vector is 16-pixel (16-pel) unit, 8-pixel (8-pel) unit, 4-pixel (4-pel) unit, integer-pixel unit, 1/2 -Pixel (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 above embodiments of the present invention can also be applied. Also, when motion vector prediction is performed, a motion vector may be selectively used for each pixel unit.

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.

For example, when the slice type is T (Tri-predictive)-slice, a prediction block is generated using at least three motion vectors, and a weighted sum of the at least three prediction blocks is calculated to obtain an encoding/decoding target block. can be used as the final prediction block of For example, when the slice type is Q (Quad-predictive)-slice, a prediction block is generated using at least 4 or more motion vectors, and a weighted sum of the at least 4 or more prediction blocks is calculated to obtain an encoding/decoding target block. can be used as the final prediction block of

The above embodiments of the present invention can be applied not only to inter-prediction and motion compensation methods using motion vector prediction, but also to inter-prediction and motion compensation methods using skip mode and merge mode.

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.

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 (11)

obtaining a current block;
Dividing the current block using a partitioning method determined based on the size of the current block;
generating a prediction block for the obtained coding block based on the division method; and
Generating a reconstruction block based on the prediction block,
When the size of the current block exceeds the preset fixed size, the partitioning method of the current block is implicitly determined as quadtree partitioning, and the current block is determined so long as the size of the current block is less than or equal to the preset fixed size. Divided by the quadtree partitioning until
When the size of the current block is less than or equal to the predetermined fixed size, a method of dividing the current block is determined based on signaled information;
Generating the prediction block,
Further comprising filtering the prediction block based on at least one of an intra-prediction mode of the coding block and a size of the coding block.
According to claim 1,
The predetermined fixed size is 64x64, video decoding method.
According to claim 1,
The information is signaled at the coding unit level, video decoding method.
According to claim 1,
In the step of filtering the prediction block,
determining a weight of a reference sample based on a position of a prediction sample included in the prediction block when the intra-prediction mode is a predetermined mode; and
And filtering the prediction block using the determined weight.
According to claim 4,
The predetermined mode is a planar mode, video decoding method.
obtaining a current block by segmenting an image;
Dividing the current block using a partitioning method determined based on the size of the current block;
generating a prediction block for the obtained coding block based on the division method; and
Generating a residual block for the coding block based on the prediction block,
When the size of the current block exceeds the preset fixed size, the partitioning method of the current block is implicitly determined by quadtree splitting, and the size of the current block is equal to or less than the preset fixed size. Dividing the current block by the quadtree partitioning;
When the size of the current block is less than or equal to the preset fixed size, encoding information on a division method of the current block;
Generating the prediction block,
Further comprising filtering the prediction block based on at least one of an intra-prediction mode of the coding block and a size of the coding block.
According to claim 6,
The predetermined fixed size is 64x64, video encoding method.
According to claim 6,
An image encoding method in which information on a division method is encoded at a coding unit level.
According to claim 6,
In the step of filtering the prediction block,
determining a weight of a reference sample based on a position of a prediction sample included in the prediction block when the intra-prediction mode is a predetermined mode; and
And filtering the prediction block using the determined weight.
According to claim 7,
The video encoding method of claim 1 , wherein the predetermined mode is a planar mode.
In the storage medium containing a bitstream,
The bitstream is
obtaining a current block by segmenting an image;
Dividing the current block using a partitioning method determined based on the size of the current block;
generating a prediction block for the obtained coding block based on the division method; and
Generated by an image encoding method comprising generating a residual block for the coding block based on the prediction block,
When the size of the current block exceeds the preset fixed size, the partitioning method of the current block is implicitly determined by quadtree splitting, and the size of the current block is equal to or less than the preset fixed size. Dividing the current block by the quadtree partitioning;
When the size of the current block is less than or equal to the preset fixed size, encoding information on a division method of the current block;
Generating the prediction block,
The storage medium further comprising filtering the prediction block based on at least one of an intra-prediction mode of the coding block and a size of the coding block.

Images