KR102321394B1 - A method for encoding/decoding a video - Google Patents

Abstract

The present invention relates to a method for performing motion compensation using motion vector prediction. The image decoding method for this may include obtaining a quantized residual signal for a current block, inverse quantizing the quantized residual signal, and determining a transform technique for inversely transforming the residual signal. . 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 reconstructed block around the current block.

Description

Video encoding/decoding method

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 by using encoding information of a neighboring block.

Recently, demand for high-resolution and high-quality images such as HD (High Definition) images and UHD (Ultra High Definition) images is increasing in various application fields. As the image data becomes higher resolution and higher quality, the amount of data relatively increases compared to the existing image data. storage costs will increase. In order to solve these problems that occur as image data becomes high-resolution and high-quality, high-efficiency image encoding/decoding technology for images having higher resolution and image quality is required.

Inter-screen prediction technology that predicts pixel values included in the current picture from pictures before or after the current picture with image compression technology, intra-picture prediction technology that predicts pixel values included in the current picture using pixel information in the current picture, Various techniques exist, such as transformation and quantization techniques for compressing the energy of the residual signal, and entropy coding techniques that assign short codes to high frequency values and long codes to low frequency values. Image data can be effectively compressed and transmitted or stored.

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

An object of the present invention is to provide a method and apparatus for deriving encoding information of a current block from a reconstructed block around 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 differential value around a current block and a motion vector differential value of the current block.

An image encoding method according to the present invention includes generating a prediction signal for a current block, generating a residual signal for the current block based on the prediction signal, and a transformation 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 a reconstructed block that has been encoded around 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 scheme for inversely 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 reconstructed block around the current block.

In the image encoding method or the image decoding method, when the current block is encoded by intra prediction, at least one of the primary transformation method and the secondary transformation method may include an intra prediction mode that is the same as that of the current block. It can be derived from blocks.

In the image encoding method or the image decoding method, when a primary transformation scheme of a neighboring block having the same intra prediction mode as the current block indicates a transformation skip, the primary transformation scheme and the secondary transformation scheme for the current block The transform scheme may be determined as transform skip.

In the image encoding method or the image decoding method, the secondary transform technique may be derived from a neighboring block in which the primary transform technique is the same as the current block.

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

In the image encoding method or the image decoding method, the motion information may include at least one of a motion vector, a reference image 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 a reconstructed block around the current block.

According to the present invention, there is an effect of improving encoding/decoding efficiency by providing a method and apparatus for encoding/decoding a difference value between a motion vector differential value around a current block and a motion vector differential value of the current block.

1 is a block diagram illustrating a configuration of an encoding apparatus to which the present invention is applied according to an embodiment.
2 is a block diagram illustrating a configuration of a decoding apparatus to which the present invention is applied according to an embodiment.
3 is a diagram schematically illustrating a split structure of an image when encoding and decoding an image.
4 is a diagram illustrating a form of a prediction unit (PU) that the encoding unit (CU) may include.
5 is a diagram illustrating a form of a transform unit (TU) that the encoding unit (CU) may include.
6 is a diagram for explaining an embodiment of an intra prediction process.
7 is a diagram for explaining an embodiment of an inter prediction process.
8 is a diagram for explaining a transform set according to an intra prediction mode.
9 is a diagram for explaining a process of conversion.
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 describe an encoding/decoding unit according to a partition type of a block.
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 division is no longer performed on blocks of 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 encoded 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 encoded 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 have various changes and can have various embodiments, specific embodiments are 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 it should be understood to include all modifications, equivalents and substitutes included in the spirit and scope of the present invention. Like reference numerals in the drawings refer to the same or similar functions throughout the various aspects. Shapes and sizes of elements in the drawings may be exaggerated for clearer description. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [0010] 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 various embodiments are different but need not be mutually exclusive. For example, certain shapes, structures, and characteristics described herein with respect to one embodiment may be embodied in other embodiments without departing from the spirit and scope of the invention. In addition, 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 intended to be taken in a limiting sense, and the scope of exemplary embodiments, if properly described, is limited only by the appended claims, along with all scope equivalents to those claimed.

In the present invention, terms such as first, second, etc. may be used to describe various elements, but the elements should not be limited by the terms. The above terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, a first component may be referred to as a second component, and similarly, a second component may also be referred to as a first component. and/or includes a combination of a plurality of related listed items or any of a plurality of related listed 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 other components may exist in between. It should be understood that there may be On the other hand, when it is mentioned that a certain element is "directly connected" or "directly connected" to another element, it should be understood that no other element is present in the middle.

Components shown in the embodiment of the present invention are shown independently to represent different characteristic functions, and it does not mean that each component is composed of separate hardware or a single software component. That is, each component is listed as each component for convenience of description, and at least two components of each component are combined to form one component, or one component can be divided into a plurality of components to perform a function, and each Integrated embodiments and separate embodiments of components are also included in the scope of the present invention without departing from the essence of the present invention.

The terms used in the present invention are only used to describe specific embodiments, and are not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly dictates otherwise. In the present invention, terms such as "comprises" or "have" are intended to designate that the features, numbers, steps, operations, components, parts, or combinations thereof described in the specification exist, but one or more other features It should be understood that this does not preclude the existence or addition of numbers, steps, operations, components, parts, or combinations thereof. That is, the description of "including" a specific configuration in the present invention does not exclude configurations other than the corresponding configuration, and it 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 components of the present invention are not essential components for performing essential functions in the present invention, but may be optional components for merely improving performance. The present invention can be implemented by including only essential components to implement the essence of the present invention, except for 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 concretely described with reference to drawings. In describing the embodiments of the present 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 is omitted, and the same reference numerals are used for the same components in the drawings. and repeated descriptions of the same components are omitted.

In addition, hereinafter, an image may mean one picture constituting a video, or may indicate a video itself. For example, "encoding and/or decoding of an image" may mean "encoding and/or decoding of a video", and may mean "encoding and/or decoding of one image among images constituting a video". may be Here, a picture may have the same meaning as an image.

Glossary of Terms

Encoder: may refer to a device that performs encoding.

Decoder: may refer to a device that performs decoding.

Parsing: It may mean determining a value of a syntax element by performing entropy decoding, or may mean entropy decoding itself.

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

Sample: A basic unit constituting a block, and values ranging from 0 to 2Bd - 1 can be expressed according to the bit depth (Bd). In the present invention, a pixel and a pixel may be used interchangeably with a sample.

Unit: It may mean a unit of image encoding and decoding. In encoding and decoding of an image, a unit may be an area generated by segmentation of one image. Also, the unit may refer to the divided unit when encoding or decoding an image by dividing it into subdivided units. In encoding and decoding of an image, a process predefined for each unit may be performed. One unit may be further divided into sub-units having a smaller size compared to the unit. According to a function, a unit is a block, a macroblock, a coding tree unit, a coding tree block, a coding unit, a coding block, and a prediction. It may mean a unit (Prediction Unit), a prediction block (Prediction Block), a transform unit (Transform Unit), a transform block (Transform Block), and the like. Also, a unit may mean including a luminance (Luma) component block, a chroma component block corresponding thereto, and a syntax element for each block in order to be distinguished from the 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. In addition, the unit information may include at least one of a unit type indicating a coding unit, a prediction unit, a transform unit, etc., a size of a unit, a depth of a unit, an encoding and decoding order of the unit, and the like.

Reconstructed Neighbor Unit: It may refer to a reconstructed unit that has already been encoded or decoded in a spatial/temporal manner around an encoding/decoding target unit. In this case, the restored neighboring unit may mean a restored neighboring block.

Neighbor block: may refer to a block adjacent to an encoding/decoding target block. A block adjacent to the encoding/decoding object block may mean a block in which a boundary is in contact with the encoding/decoding object block. The neighboring block may refer to a block located at an adjacent vertex of an encoding/decoding target block. The neighboring block may mean a reconstructed neighboring block.

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

Symbol: may mean an encoding/decoding target unit syntax element, a coding parameter, a value of a transform coefficient, and the like.

Parameter set: may correspond to header information among structures in the bitstream, and may include 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. Also, the parameter set may have a meaning including slice header and tile header information.

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

Prediction Unit: A basic unit for performing inter prediction or intra prediction and compensation therefor, and one prediction unit may be divided into a plurality of small partitions. In this case, each of the plurality of partitions becomes a basic unit when the prediction and compensation are performed, and the partition into which the 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: may refer to a form in which a prediction unit is divided.

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

Inter Prediction Indicator: In inter prediction, it may mean the inter prediction direction (unidirectional prediction, bidirectional prediction, etc.) of the encoding/decoding target block, and It may mean the number of reference images used when performing an encoding/decoding process, and may mean the number of prediction blocks used when an encoding/decoding target block performs inter prediction or motion compensation.

Reference picture index: may mean an index for a specific reference picture in the reference picture list.

Reference picture: It may mean a picture referenced by a specific unit for inter prediction or motion compensation, and the reference picture may also be referred to as a reference picture.

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

Motion Vector Candidate: When a motion vector is predicted, it may mean a unit that becomes a prediction candidate or a motion vector of the unit.

Motion Vector Candidate List: may refer to a list constructed using motion vector candidates.

Motion Vector Candidate Index: An indicator indicating a motion vector candidate in a motion vector candidate list, it may also be referred to as an index of a motion vector predictor.

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

Merge Candidate List: may refer to 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 and a motion vector for the list.

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

Transform unit: may refer to a basic unit when performing residual signal encoding/decoding such as transform, inverse transform, quantization, inverse quantization, and transform coefficient encoding/decoding, and one transform unit is It may be divided into a plurality of conversion units having a small size. The transformation unit may have various sizes and shapes, and in particular, the shape of the transformation 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: may refer to a process of multiplying a transform coefficient level by a factor, and may generate a transform coefficient as a result. Scaling may also be referred to as 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): may mean a difference value between a predicted quantization parameter and a quantization parameter of an encoding/decoding target unit.

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

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

Non-zero transform coefficient (Non-zero Transform Coefficient): may mean a transform coefficient having a value of which the value of the transform coefficient is not 0 or a level of a transform coefficient having a value of which the magnitude is not 0.

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

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

Default matrix: may mean a predetermined quantization matrix predefined in the encoder and the decoder.

Non-default matrix: It may mean a quantization matrix that is not predefined in the encoder and the decoder, and is transmitted/received by the user.

Coding Tree Unit: 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 splitting methods, such as a quad tree and a binary tree, to configure 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 becomes a processing unit in an image decoding/encoding process.

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

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

The encoding apparatus 100 may be a video encoding apparatus or an image encoding apparatus. 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 prediction 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 encoder 150 , an inverse quantizer 160 , an inverse transform unit 170 , an adder 175 , a filter unit 180 , and a reference picture buffer 190 .

The encoding apparatus 100 may encode an input image in an intra mode and/or an inter mode. Also, the encoding apparatus 100 may generate a bitstream by encoding an input image, and may output the generated bitstream. When the intra mode is used as the prediction mode, the switch 115 may be switched to the intra mode, and when the inter mode is used as the prediction mode, the switch 115 may be switched to the inter mode. 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 the input block of the input image. Also, after the prediction block is generated, the encoding apparatus 100 may encode a residual between the input block and the prediction block. 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 object block.

When the prediction mode is the intra mode, the intra prediction unit 120 may use a pixel value of a block already encoded around the current block as a reference pixel. The intra prediction unit 120 may perform spatial prediction using a reference pixel, and may generate prediction samples for an input block through spatial prediction. Here, intra prediction may mean intra prediction.

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

The motion compensator 112 may generate a prediction block by performing motion compensation using a motion vector. Here, the motion vector may be a two-dimensional 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 predictor 111 and the motion compensator 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, a method of motion prediction and motion compensation of a prediction unit included in a corresponding coding unit based on a coding unit is a skip mode, a merge mode, and an AMVP mode. ), it is possible to determine which method of the current picture reference mode is used, and inter prediction or motion compensation may 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 object block belongs. In order to specify the pre-reconstructed region, a motion vector for the current picture reference mode may be defined. Whether the encoding object block is encoded in the current picture reference mode may be encoded using a reference image index of the encoding object block.

The subtractor 125 may generate a residual block by using the difference between the input block and the prediction block. The residual block may be referred to as a residual signal.

The transform unit 130 may perform transform on the residual block to generate a transform coefficient, and may output a 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 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 the quantization parameter, and may output the quantized transform coefficient level. In this case, the quantization unit 140 may quantize the transform coefficients 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 coding parameter values calculated in the encoding process. and can output a bitstream. The entropy encoding unit 150 may perform entropy encoding on information for decoding an image in addition to information on pixels of the image. For example, information for decoding an image may include a syntax element or the like.

When entropy encoding is applied, a small number of bits are allocated to a symbol having a high probability of occurrence and a large number of bits are allocated to a symbol having a low probability of occurrence to express the symbol, so that bits for symbols to be encoded The size of the column may be reduced. Accordingly, compression performance of image encoding may be improved through entropy encoding. The entropy encoder 150 may use an encoding method such as exponential Golomb, Context-Adaptive Variable Length Coding (CAVLC), or Context-Adaptive Binary Arithmetic Coding (CABAC) 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 encoder 150 derives a binarization method of a target symbol and a probability model of a target symbol/bin, and then performs arithmetic encoding using the derived binarization method or probability model. You may.

The entropy encoder 150 may change the two-dimensional block form coefficient into a one-dimensional vector form through a transform coefficient scanning method in order to encode the transform coefficient level. For example, by scanning the coefficients of a block using up-right scanning, it can be changed into a one-dimensional vector form. A vertical scan that scans a two-dimensional block shape coefficient in a column direction and a horizontal scan that scans a two-dimensional block shape coefficient in a row direction may be used instead of the upright scan according to the size of the transform unit and the intra prediction mode. That is, according to the size of the transform unit and the intra prediction mode, it is possible to determine which scanning method among the upright scan, the vertical scan, and the horizontal scan is to be used.

Coding parameters, such as syntax elements, may include not only information encoded by an encoder and transmitted to a decoder, but also information derived from an encoding or decoding process, and may mean information necessary for encoding or decoding an image. have. For example, block size, block depth, block division information, unit size, unit depth, unit division information, quad tree type division flag, binary tree type division flag, binary tree type 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, motion merge mode use or not, motion merge candidate, motion merge candidate list, skip mode use or not, interpolation filter type, motion vector size, motion vector expression accuracy , transform type, transform size, information on whether to use additional (secondary) transform, presence or absence of residual signal information, coded block pattern, coded block flag, quantization parameter, quantization matrix, filter in loop Information, In-loop filter application information, In-loop filter coefficients, 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, and information on a luminance signal or a chrominance signal may be included in the encoding parameter. have.

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 a difference between the original signal and the predicted signal. The residual block may be a residual signal in block units.

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 apparatus 100 may decode the encoded current image again and store the decoded image as a reference image. Inverse quantization and inverse transformation of the encoded current image for decoding may be processed.

The quantized coefficient may be dequantized by the dequantization unit 160 . An inverse transform may be performed in the inverse transform unit 170 . The inverse-quantized and inverse-transformed coefficients may be summed 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 applies 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 be referred to as an in-loop filter.

The deblocking filter may remove block distortion generated at the 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 can be applied according to the required deblocking filtering strength. In addition, in applying the deblocking filter, horizontal filtering and vertical filtering may be concurrently processed when performing vertical filtering and horizontal filtering.

In the sample adaptive offset, an appropriate offset value may be added to a pixel value to compensate for an encoding error. The sample adaptive offset may correct an offset from the original image on a pixel-by-pixel basis with respect to the image on which the deblocking has been performed. In order to perform offset correction on a specific picture, a method of dividing pixels included in an image into a certain number of regions, determining the region to be offset and applying the offset to the region, or taking edge information of each pixel into consideration can be used to apply

The adaptive loop filter may perform filtering based on a value obtained by comparing the reconstructed image and the original image. After dividing the pixels included in the image into a predetermined group, one filter to be applied to the corresponding group is determined, and filtering can be performed differentially for each group. As for the information on whether to apply the adaptive loop filter, the luminance signal may be transmitted for each coding unit (CU), and the shape and filter coefficients of the adaptive loop filter to be applied may vary according to each block. In addition, the adaptive loop filter of the same shape (fixed shape) may be applied regardless of the characteristics of the target block.

The reconstructed block that has passed through the filter unit 180 may be stored in the reference picture buffer 190 .

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

The decoding apparatus 200 may be a video decoding apparatus or an image decoding apparatus.

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 compensator 250 , and an adder 255 . , a filter unit 260 and a reference picture buffer 270 may be included.

The decoding apparatus 200 may receive the bitstream output from the encoding apparatus 100 . The decoding apparatus 200 may perform decoding on the bitstream in an intra mode or an inter mode. Also, the decoding apparatus 200 may generate a reconstructed image through decoding and may output the reconstructed 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 the 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 object block by adding the reconstructed residual block and the prediction block. The decoding object block may be referred to as a current block.

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

The entropy decoding unit 210 may change the one-dimensional vector form coefficient into a two-dimensional block form through a transform coefficient scanning method in order to decode the transform coefficient level. For example, by scanning the coefficients of the block using up-right scanning, it can be changed into a two-dimensional block form. A vertical scan or a horizontal scan may be used instead of the upright scan according to the size of the transform unit and the intra prediction mode. That is, according to the size of the transform unit and the intra prediction mode, it is possible to determine which scanning method among the upright scan, the vertical scan, and the horizontal scan is to be used.

The quantized transform coefficient level may be inverse quantized by the inverse quantizer 220 , and may be inversely transformed by the inverse transform unit 230 . As a result of inverse quantization and inverse transformation of the quantized transform coefficient level, a reconstructed residual block may be generated. In this case, the inverse quantizer 220 may apply a quantization matrix to the quantized transform coefficient level.

When the intra mode is used, the intra prediction unit 240 may generate a prediction block by performing spatial prediction using pixel values of an already decoded block around the decoding object block.

When the inter mode is used, the motion compensator 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, a motion compensation method of a prediction unit included in a corresponding coding unit based on a coding unit is selected from among skip mode, merge mode, AMVP mode, and current picture reference mode. It may be determined which method is used, and motion compensation may 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 object block belongs. A motion vector for the current picture reference mode may be used to specify the pre-reconstructed region. A flag or an index indicating whether the decoding object block is a block encoded in the current picture reference mode may be signaled or inferred through the reference image index of the decoding object block. In the current picture reference mode, the current picture may exist at a fixed position (eg, a position where the reference image index is 0 or the last position) in the reference image list for the decoding object block. Alternatively, it may be variably located in the reference picture list, and for this, a separate reference picture index indicating the location of the current picture may be signaled.

The reconstructed residual block and the prediction block may be added through an adder 255 . A block generated by adding the reconstructed residual block and the prediction 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.

FIG. 3 is a diagram schematically illustrating a split structure of an image when encoding and decoding an image. 3 schematically shows 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 that collectively refers to a block including 1) a syntax element and 2) image samples. For example, "division of a unit" may mean "division of a block corresponding to a unit". The block division information may include information about the depth of the unit. The depth information may indicate the number and/or degree to which a unit is divided.

Referring to FIG. 3 , an image 300 is sequentially divided in units of a Largest Coding Unit (LCU), 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 on the size of the sub-unit.

The partition structure may mean a distribution of coding units (CUs) within the LCU 310 . A CU may be a unit for efficiently encoding an image. Such a distribution may be determined according to whether one CU is divided into a plurality of CUs (a positive integer of 2 or more including 2, 4, 8, 16, etc.). The horizontal size and vertical size of the CU created by division are half the horizontal size and half the vertical size of the CU before division, respectively, or a size smaller than the horizontal size and vertical size of the CU before division according to the number of divisions. 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 performed recursively up to a predefined depth. The depth information may be information indicating 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 a Smallest Coding Unit (SCU) may be a predefined maximum depth. Here, the LCU may be a coding unit having the largest coding unit size as described above, and the SCU may be a coding unit having the smallest coding unit size.

The division starts from the LCU 310, and the depth of the CU increases by 1 whenever the horizontal size and the vertical size of the CU are reduced by the division. For each depth, an undivided CU may have a size of 2Nx2N. In the case of a divided CU, a CU having a size of 2Nx2N may be divided into a plurality of CUs having a size of NxN. The size of N is halved for each increase in depth by 1.

For example, when one coding unit is divided into 4 coding units, the horizontal and vertical sizes of the divided 4 coding units may have half sizes compared to the horizontal and vertical sizes of the coding units before splitting. have. 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 unit is divided into a quad-tree.

For example, when one coding unit is split into two coding units, the horizontal or vertical size of the two split coding units may have a half size compared to the horizontal or vertical size of the coding unit before splitting. . For example, when a 32x32 coding unit is vertically split into two coding units, each of the two split coding units may have a size of 16x32. For example, when a 32x32 coding unit is horizontally split into two coding units, the two split coding units may each have a size of 32x16. When one coding unit is split into two coding units, it can be said that the coding unit is split 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. An SCU of depth 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 depth 0. A CU of 32x32 pixels may be expressed as depth 1. A CU of 16x16 pixels may be expressed as depth 2. A CU of 8x8 pixels, which is an SCU, may be expressed as depth 3 .

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

4 is a diagram illustrating a form of a prediction unit (PU) that the encoding unit (CU) may include.

A CU that is no longer split among CUs split from an LCU may be divided into one or more prediction units (PUs). This treatment may also be referred to as segmentation.

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

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

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

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

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

For example, when one prediction unit is divided into 4 prediction units, the horizontal and vertical sizes of the divided 4 prediction units may have half sizes compared to the horizontal and vertical sizes of the prediction units before division. have. For example, when a 32x32 prediction unit is divided into 4 prediction units, each of the 4 divided 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 into a quad-tree.

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

5 is a diagram illustrating a form of a transform unit (TU) that the encoding unit (CU) may include.

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

Among CUs split from an LCU, a CU that is no longer split into CUs may be split into one or more TUs. In this case, the partition 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 the 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 and/or horizontal lines dividing the CU. A CU may be divided into symmetric TUs or may be divided into asymmetric TUs. For splitting into an asymmetric TU, information about the size/shape of a TU may be signaled, and may be derived from information about the size/shape of a CU.

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 split into one or more transform units, and one transform unit may also be split into one or more transform units.

For example, when one transformation unit is divided into 4 transformation units, the horizontal and vertical sizes of the divided 4 transformation units may have half sizes compared to the horizontal and vertical sizes of the transformation units before being divided. have. 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 transformation unit is divided into two transformation units, the horizontal or vertical size of the divided two transformation units may have a half size compared to the horizontal or vertical size of the transformation unit before division. . For example, when a 32x32 transform unit is vertically divided into two transform units, the two divided transform units may each 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 transform unit is divided into two transform units, it can be said that the transform 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, a Discrete Cosine Transform (DCT), a Discrete Sine Transform (DST), or a KLT may be used as the 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 the size/form of the transform block, and in certain cases indicates the transform method 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 by 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 mode and the directional mode.

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 size of the block. For example, at least one of 35 or 67 blocks may be fixed regardless of the size of the block.

The number of intra prediction modes may be different depending on 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.

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

In order to encode/decode the current block using intra prediction, an operation of checking whether samples included in a neighboring reconstructed block are available as reference samples of the encoding/decoding target block may be performed. When there are samples that cannot be used as reference samples of the encoding/decoding target block, a sample value is copied to samples that cannot be used as reference samples by using at least one or more of samples included in a neighboring reconstructed block and/or It can be used as a reference sample of an encoding/decoding target block by interpolation.

During intra prediction, a filter may be applied to at least one of a reference sample and a prediction sample based on at least one of an intra prediction mode and a size of 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 the prediction sample may be different according to at least one of an intra prediction mode and a size/shape of the current block. The type of the filter may vary according to at least one of the number of filter taps, a filter coefficient value, and a filter strength.

Among the intra prediction modes, the non-directional planar mode, when generating the prediction block of the target encoding/decoding block, sets the sample values in the prediction block according to the sample position to the upper reference sample of the current sample, the left reference sample of the current sample, The upper-right reference sample of the current block may be generated as a weighted sum of the lower-left reference samples of the current block.

Among the intra prediction modes, the non-directional DC mode may be generated as an average value of the upper reference samples of the current block and the left reference samples of the current block when the prediction block of the target encoding/decoding block is generated. In addition, filtering may be performed using reference sample values on one or more upper 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, a prediction block may be generated using upper right and/or lower left reference samples, and the directional modes may have different directions. In order to generate a predicted sample value, interpolation in units of real numbers may be performed.

In order to perform the intra prediction method, the intra prediction mode of the current prediction block may be predicted from the intra prediction mode of the prediction block existing around the current prediction block. When the intra prediction mode of the current prediction block is predicted using the mode information predicted from the neighboring intra prediction mode, 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 Information that the intra prediction modes of the block and the neighboring prediction block are the same may be transmitted, and if the intra prediction modes of the current prediction block and the neighboring prediction block are different from each other, entropy encoding is performed and the intra prediction mode of the encoding/decoding target block information can be encoded.

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

The rectangle shown in FIG. 7 may represent an image (or a picture). Also, an arrow in FIG. 7 may indicate a prediction direction. That is, the image may be encoded and/or decoded according to the prediction direction. Each image may be classified into an I picture (intra picture), a P picture (uni-predictive picture), a B picture (bi-predictive picture), etc. according to the encoding type. Each picture may be encoded and decoded according to the encoding type of each picture.

When an image to be encoded is an I picture, the image may be intra-encoded with respect to the image itself 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 the forward direction. When an image to be encoded is a B picture, it can be encoded through inter prediction or motion compensation using reference pictures in both forward and backward directions, and inter prediction or motion using reference pictures in one of the forward and backward directions. 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. Images of P-pictures and B-pictures that are encoded and/or decoded using a reference image may be regarded as images for which inter prediction is used.

Below, inter prediction according to an embodiment will be described in detail.

Inter prediction or motion compensation may be performed using a reference picture and motion information. In addition, the inter prediction may use the skip mode described above.

The reference picture may be at least one of a previous picture of the current picture or a subsequent picture of the current picture. In this case, the inter prediction may be performed on the 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 in 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.

In the inter prediction, a reference picture and a reference block corresponding to the current block in the reference picture may be selected, and a prediction block for the current block may be generated using the selected reference block. The current block may be a block to be currently encoded or decoded among blocks of the current picture.

Motion information may be derived during inter prediction by each of the encoding apparatus 100 and the decoding apparatus 200 . Also, the derived motion information may be used to perform inter prediction. In this case, the encoding apparatus 100 and the decoding apparatus 200 use motion information of a reconstructed neighboring block and/or motion information of a collocated block to achieve encoding and/or decoding efficiency. can improve The collocated block may be a block corresponding to a spatial position of an encoding/decoding target block 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. Also, the reconstruction block may be a neighboring 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 object block is a block vertically adjacent to a neighboring block horizontally adjacent to the encoding/decoding object block or a block horizontally adjacent to a neighboring block vertically adjacent to the encoding/decoding object block can

Each of the encoding apparatus 100 and the decoding apparatus 200 may determine a block existing at a position spatially corresponding to the encoding/decoding target block in the collocated picture, and determine a predefined relative position based on the determined block. can The predefined relative position may be a position inside and/or outside a block that is spatially located at a position 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 and predefined relative positions. Here, the collocated picture may be one picture from among at least one reference picture included in the reference picture list.

A method of deriving motion information may vary according to a prediction mode of an encoding/decoding object block. For example, as a prediction mode applied for inter prediction, there may be advanced motion vector prediction (AMVP) and a 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 a motion vector candidate. (motion vector candidate list) can be generated. 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, the motion vector of the collocated block may be referred to as a temporal motion vector candidate, and the motion vector of the reconstructed neighboring block may be referred to as a spatial motion vector candidate.

The bitstream generated by the encoding apparatus 100 may include a motion vector candidate index. That is, the encoding apparatus 100 may generate a bitstream by entropy-encoding the motion vector candidate index. The motion vector candidate index may indicate an optimal motion vector candidate selected from among 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 entropy-decodes the motion vector candidate index from the bitstream, and uses the entropy-decoded motion vector candidate index to select the motion vector candidate of the decoding object block from among the motion vector candidates included in the motion vector candidate list. .

The encoding apparatus 100 may calculate a motion vector difference (MVD) between a motion vector of an encoding object block and a motion vector candidate, and may entropy-encode the MVD. The bitstream may include entropy-encoded MVDs. The MVD may be transmitted from the encoding apparatus 100 to the decoding apparatus 200 through a bitstream. In this case, 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, and the like. 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 the neighboring block, 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 the decoding object block based on the derived motion vector and reference image index information.

As another example of a method of deriving motion information, there is a merge mode. The merge mode may refer to merging of motions for a plurality of blocks. The merge mode may mean applying motion information of one block to another block as well. When the merge mode is applied, each of the encoding apparatus 100 and the decoding apparatus 200 generates 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 prediction indicator. The prediction indicator may 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 apparatus 100 may entropy-encode predefined information to generate a bitstream and then transmit it to the decoding apparatus 200 . The bitstream may include predefined information. The predefined information includes 1) a merge flag, which is information indicating whether to perform the merge mode for each block partition, and 2) which block among neighboring blocks adjacent to the encoding target block to be merged with. information about a merge index may be included. For example, the 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 generated before the merge mode is performed. The motion information stored in the merge candidate list includes motion information of a neighboring block adjacent to the encoding/decoding object block, motion information of a block collocated to the encoding/decoding object block in a reference image, and a motion already present in the merge candidate list. It may be at least one of new motion information generated by a combination of information and a zero merge candidate. Here, motion information of a neighboring block adjacent to the encoding/decoding object block is a spatial merge candidate, and motion information of a block collocated to the encoding/decoding object 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 a neighboring block is applied to an encoding/decoding target block as it is. The 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 it to the decoding apparatus 200 through a bitstream. The encoding apparatus 100 may not transmit other information to the decoding apparatus 200 . For example, the other information may be syntax element information. The syntax element information may include at least one of motion vector difference information, a coding block flag, and a transform coefficient level.

The residual signal generated after intra- or inter-picture prediction may be transformed into the frequency domain through a transformation process as part of the quantization process. Various DCT and DST kernels other than DCT type 2 (DCT-II) can be used for the first transform performed at this time, and these transform kernels perform one-dimensional transform (1D transform) for the residual signal in the horizontal and/or vertical direction. Transformation may be performed by a separate transform performed respectively, or transformation may be performed by a 2D non-separable transform.

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

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

transformation 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, as shown in FIG. 8 , after defining different transform sets in the horizontal or vertical direction according to the intra prediction mode, the encoder/decoder determines the intra prediction mode of the current encoding/decoding target block and the A transform and/or an inverse transform may be performed using a transform included in the corresponding transform set. In this case, the transform set is not entropy-encoded/decoded, but may be defined according to the same rule in the encoder/decoder. In this case, entropy encoding/decoding indicating which transform is used among transforms belonging to the corresponding transform set may be performed. For example, if the size of the block is 64x64 or less, a total of three transform sets are configured as shown in the example in Figure 2 according to the intra prediction mode, and each of the three transforms is used for horizontal and vertical transforms. After performing by combining a total of nine multiple transform methods, encoding efficiency can be improved by encoding/decoding the residual signal using an optimal transform 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 was 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 above-described primary transformation is completed, the encoder may perform secondary transformation to increase energy concentration of transformed coefficients as in the example of FIG. 9 . Secondary transformation may also perform separation transformation in which one-dimensional transformation is performed in horizontal and/or vertical directions, respectively, or two-dimensional non-separation transformation may be performed, and used transformation information is transmitted or present and surrounding It may be implicitly derived from 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 rule in the encoder/decoder rather than 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 of a residual signal through intra-picture or inter-picture prediction.

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

The decoder may perform second-order inverse transform according to whether or not second-order inverse transform is performed, and may perform first-order inverse transform on the result of performing second-order inverse transform according to whether first-order inverse transform is performed.

The above-described primary transform and secondary transform may be applied to at least one signal component among luminance/chrominance components or may be applied according to an arbitrary coding block size/shape, and whether or not to be used in an arbitrary coding block and the used primary transform Entropy encoding/decoding of an index indicating a /second-order transformation or implicitly inducing an encoder/decoder according to at least one of current/peripheral encoding information may be performed.

After the first and/or second transform is completed, the residual signal generated after intra or inter prediction is subjected to a quantization process, and then the quantized transform coefficient is subjected to an entropy encoding process. In this case, the quantized transform 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 or a minimum block size/shape.

In addition, the 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. In this case, at least one of a diagonal scan, a horizontal scan, and a vertical scan may be performed as the inverse scanning method.

For example, when the size of the current coding block is 8x8, the residual signal for the 8x8 block is subjected to primary and secondary transforms and quantization, followed by three scanning order methods shown in FIG. 10 for each 4x4 sub-block. Entropy encoding may be performed while scanning the transform coefficients quantized according to at least one of . In addition, entropy decoding can be performed while inversely scanning the quantized transform coefficients. The inverse-scanned quantized transform coefficient becomes a transform coefficient after inverse quantization, and at least one of a second-order inverse transform or 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 partition 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). have. Here, split_flag is a flag indicating whether the block is split, QB_flag is a flag indicating whether the block is split in a quadtree form or a binary tree form, quadtree_flag is a flag indicating whether the block is split in a quadtree form, binarytree_flag may be a flag indicating whether the block is partitioned in a binary tree format, and Btype_flag may be a flag indicating vertical or horizontal partitioning when the block is partitioned in a binary tree format.

If the split flag is 1, it may indicate that it has been split, if 0, it may indicate that it has not been split. This may indicate quadtree partitioning. In the case of the binary tree division type flag, 0 may indicate horizontal division and 1 may indicate vertical division. Conversely, 0 may indicate vertical division and 1 may indicate horizontal division.

For example, the partition information for FIG. 11 may 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 may 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

In the partitioning method, partitioning may be possible only in a quad tree or only in a binary tree depending on the size/shape of the block. 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 the depth information of the block, and the depth information may be signaled.

When the size of the block falls within a predetermined range, it may be possible to divide only into a quadtree. Here, the predetermined range may be defined as at least one of a size of a maximum block and a size of a minimum block that can be split only by the quadtree. Information indicating the size of the maximum/minimum block allowed for division in the quadtree form may be signaled through a bitstream, and the information may be signaled in units of at least one of a sequence, a picture parameter, or a slice (segment). have. Alternatively, the size of the maximum/minimum block may be a fixed size preset in the encoder/decoder. For example, when the size of the block corresponds to 256x256 to 64x64, it may be possible to divide only into a quadtree. In this case, the split_flag may be a flag indicating whether to split the quadtree.

When the size of the block falls within a predetermined range, it may be possible to partition only into a binary tree. Here, the predetermined range may be defined as at least one of a size of a maximum block that can be split only by a binary tree or a size of a minimum block. Information indicating the size of the maximum/minimum block allowed to split in the binary tree form may be signaled through a bitstream, and the information may be signaled in units of at least one of a sequence, a picture parameter, or a slice (segment). have. Alternatively, the size of the maximum/minimum block may be a fixed size preset in the encoder/decoder. For example, when the size of the block corresponds to 16x16 to 8x8, partitioning may be possible only in 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 divided into a binary tree, when the divided block is further divided, it can be divided into only a binary tree.

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

In addition to the quadtree-based binary tree splitting, after the binary tree splitting, quadtree-based splitting may be possible.

When a block is divided based on a quadtree and/or a binary tree, a block corresponding to a leaf node according to the final division result of the block may be set as one encoding/decoding unit. That is, when a block having an arbitrary size or an arbitrary shape is no longer 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 this may be performed.

12 is a diagram exemplified to describe an encoding/decoding unit according to a partition type of a block. In the example shown in FIG. 12 , a solid line is for separating blocks generated by quadtree partitioning, and a dotted line is for separating blocks generated by binary tree partitioning. As in the example shown in FIG. 12 , assuming that the structure of the coding block is determined, the finally divided node may be defined as a binary leaf node through actual practice and a dotted line. A block corresponding to a binary leaf node is encoded/decoded (e.g., 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 block structure based on a quadtree 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. As an example, the block structure may be the same for the luminance and chrominance components, or may be different for the luminance and chrominance components according to arbitrary encoding parameter conditions. Here, the same block structure of the luminance component and the chrominance component may mean that the chrominance component inherits 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 may have the same block structure in an intra frame or an intra slice according to a picture or slice type to be currently encoded/decoded. At this time, whether to set the same or different block structures for luminance and chrominance components constituting an intra picture or an intra picture slice is determined after obtaining a rate-distortion cost function according to each block structure. , can be determined through an encoding process of selecting a block structure in which the cost function is minimized.

The encoding apparatus may entropy-encode information indicating whether to use the same block structure for each color component and transmit it to the decoding apparatus. In this case, the information includes 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 an encoding unit (or encoding). block) may be coded in at least one of them.

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

Alternatively, encoding parameter information indicating whether a block structure for each color component is the same for an intra-picture slice or an inter-picture slice may be transmitted through a slice header.

Alternatively, encoding parameter information indicating whether the block structure for each color component is the same with respect to the maximum encoding unit or the encoding unit may be transmitted in units of the maximum encoding unit or the encoding unit.

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

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

For example, if it is assumed that the predetermined condition indicates that the block size is less than or equal to the reference value, and that binary tree division is not allowed for a block that satisfies the predetermined condition, information related to binary tree division ( For example, encoding/decoding of the quad/binary tree flag (QB_flag), the binary tree split flag (binaraytree_flag), or the binary tree split 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 divided into a quad tree.

It is not limited to the described example, and it may be set not to allow quadtree division for a block that satisfies a predetermined condition. In this case, for a block satisfying a predetermined condition, encoding/decoding of information related to quadtree splitting (eg, a quad/binary tree flag (QB_flag) or a quadtree split flag (quadtree_flag), etc.) 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 split into a binary tree.

As another example, with respect to a block satisfying a predetermined condition, any form of division may not be allowed. In this case, no division information may be encoded/decoded for a block that satisfies a predetermined condition.

A process of determining whether to omit encoding/decoding of partition information will be described in more detail with reference to the drawings.

13 is a flowchart illustrating a process of determining whether to decode information related to binary tree partitioning. For convenience of description, in this embodiment, it is assumed that binary tree-based partitioning is not allowed for a block satisfying 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 a size, a shape, and a division depth of a block. The predetermined condition includes, based on information related to the predetermined condition, 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. Whether or not the block depth is less than or equal to a threshold value may be set.

The information related to the predetermined condition may be predefined in the encoder and the decoder. Here, the information related to the predetermined condition may indicate at least one of the size of the block defining the predetermined condition, the shape of the block, or the depth of the block. For example, the size/form or the division depth of a block in which encoding/decoding of partition information is omitted may have a fixed value predefined in the encoder and the decoder. Alternatively, information related to a predetermined condition may be variably determined by an encoding parameter indicating the size/shape of the encoding/decoding target block or the 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. In this case, the predetermined coding region has a size/shape smaller than that of a picture or slice currently being coded/decoded, and a block of any size or shape included in the largest coding unit (LCU or CTU) or the largest coding unit (eg, the maximum a block generated by dividing the coding unit into a quadtree) and the like. Information related to a predetermined condition may be expressed in the form of a maximum size of a block and/or a minimum size of a block, or may be expressed in a form of a maximum depth of a block and/or a minimum size of a block.

The encoder compares the rate-distortion between a result of performing quadtree- and binary-tree-based encoding and a result of performing quadtree-based encoding to determine a 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 for which binary tree division is no longer performed. Also, the decoder may decode information related to a predetermined condition in which binary tree splitting is not allowed 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 division for the current block may be omitted.

On the other hand, when the current block does not satisfy a predetermined condition, information related to the binary tree division of the current block may be decoded according to whether the current block has been divided into a quadtree ( S1303 ). For example, if quadtree division is not performed on the current block, information related to binary tree division for the current block may be decoded.

That is, 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, it is possible to determine whether to encode/decode block division information for the current block.

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, an arbitrary shape, or an arbitrary depth may be encoded/decoded. Here, the information indicating whether block division is allowed may include information indicating whether quadtree division exists (eg, NoPresent_Quadtree_flag) or information indicating whether binary tree division exists (eg, NoPresent_Binarytree_flag).

When it indicates that block division is not allowed for a block having any size, arbitrary shape, or arbitrary depth, block division may not be allowed for not only the corresponding block but also the sub-blocks. Here, the sub-block may include at least one of a block having a size smaller than the corresponding block, a block having the same shape as the corresponding block, a block having a division depth greater than that of the corresponding block, or a lower node block of the corresponding block.

For example, information indicating whether binary tree partitioning exists for a block having an arbitrary size/shape is signaled, and when the information indicates that there is no binary tree partitioning, not only the block, but also a size/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) ) of at least one) of encoding/decoding may be omitted.

It is not limited to the described example, and it is also possible to signal information indicating whether a quadtree partition exists or whether 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. In this case, the predetermined coding region has a size/shape smaller than that of a picture or slice currently being coded/decoded, and a block of any size or shape included in the largest coding unit (LCU or CTU) or the largest coding unit (eg, the maximum a block generated by dividing the coding unit into a quadtree) and the like. The encoder determines the block structure by comparing the rate-distortion between the result of performing quadtree- and binary-tree-based encoding on blocks of arbitrary size/shape and the result of performing quadtree-based encoding, and , it is possible to determine whether to encode information indicating whether binary tree splitting is allowed according to the determined block structure.

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

As another example, information on the size, shape, or depth of a block in which information indicating whether block division is permitted may be encoded/decoded at a higher level. As an example, information on the 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 permitted 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 description, in the present embodiment, it is assumed that information on whether binary tree splitting is allowed is signaled only for the current block.

First, information indicating whether or not the binary tree is split for the current block may be decoded (S1401).

When the information indicates that binary tree partitioning is not allowed (S1402), decoding of binary tree partitioning information for the current block may be omitted. In addition, the binary tree division information may not be decoded even for a sub-block generated by dividing the current block into a quadtree.

On the other hand, if the information indicates that binary tree splitting is permitted (S1402), information related to binary tree splitting may be decoded according to whether the current block is quadruly split (S1403). For example, if quadtree division is not performed on the current block, information related to binary tree division for the current block may be decoded. In addition, with respect to a sub-block generated when the current block is divided into a quad tree or a binary tree, information related to the division of a binary tree may be decoded according to whether the sub-block is divided into a quad tree.

15 to 17 are diagrams for explaining an example in which binary tree division is no longer performed on blocks of 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 quadtree division exists without binary tree division within the maximum coding unit through rate-distortion optimization performed by the encoding apparatus. do.

If information that binary tree division is not performed on a block of a predetermined size is not encoded/decoded, as in the example shown in FIG. 16, whether binary tree division is performed on a block for which quadtree division is no longer performed. Encoding/decoding of information about

However, when encoding/decoding information that binary tree splitting is not performed on blocks of 128x128 size or smaller, as in the example shown in FIG. 17, for blocks smaller than 128x128 size, binary tree splitting is performed There is no need to encode/decode the information. Accordingly, the amount of information to be encoded may be reduced, and encoding/decoding efficiency may be increased.

As previously described with reference to FIG. 13 , the encoder may encode information about the size (eg, information representing 128x128), shape, or depth of a block in which binary tree splitting is not allowed, and transmit it to the decoding apparatus. The decoding apparatus may decode information about the size of a block in which binary tree division is not performed from the bitstream, and may not decode information related to binary tree division any more with respect to a block having a size less than or equal to the size indicated by the decoded information.

As another example, as described above with reference to FIG. 14 , the encoding apparatus may encode information indicating that binary tree division is not allowed for an arbitrary size block in which binary tree division is not performed, and transmit it to the decoding apparatus. 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 , it is exemplified that NoPresent_BinaryTree_flag is signaled for a block having a size of 128x128.

16 and 17, when quadtree or binary tree division is performed, the value of the flag is 1, otherwise, the value of the flag is set to 0, but the opposite setting is also possible.

An embodiment related to disallowing block division may be applied to a luminance component and a chrominance component. At this time, information indicating that block division is not allowed (eg, information indicating block size, shape, or size in which block division is not allowed, information indicating whether block division is allowed, etc.) It may be commonly applied, or may be signaled separately for the luminance component and the chrominance component. In the case of entropy encoding/decoding of the information, a truncated rice binarization method, a K-th order Exp_Golomb binarization method, a limited K-order exponent-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 transformation and scanning for the current block will be described.

In performing encoding/decoding of the residual signal of the current block, at least one or more of the encoding information of the residual signal of the current block through encoding information of the residual signals of blocks that have been encoded/decoded around the current block are encoded into the encoder/ It can be derived implicitly in the decoder. 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 primary transform and 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 a residual signal generated after intra prediction.

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

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 encoded by intra prediction.

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

When a neighboring block encoded in the same intra prediction mode as the intra prediction mode of the current block exists, encoding information for 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, and scanning information of the current block may be derived from a neighboring block having the same intra prediction mode as that of the current block.

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

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

For example, when the intra prediction mode of the current block is determined as 23 (mode 23) and at least one intra prediction mode among neighboring blocks adjacent to the current block is also determined as 23 (mode 23), the intra prediction mode is The first-order transform applied to the residual signal of the neighboring block, number 23, may be used as the first-order transform on the residual signal of the current block. For example, if the residual signal of a 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 primary transformation of the residual signal of the current block is also horizontal The direction can 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 the neighboring block of the current block, the quadratic transform of the current block is set to be the same as the quadratic transform applied to the neighboring block having the same intra prediction mode as the current block. can Accordingly, encoding/decoding of encoding information (eg, transform information (or transform index) on the secondary transform) required for secondary transformation of the residual signal of the current block may be omitted.

For example, when the intra prediction mode of the current block is determined as No. 35 (mode 35) and at least one intra prediction mode among neighboring blocks adjacent to the current block is also determined as No. 35 (mode 35), the intra prediction mode is The quadratic transform applied to the residual signal of the neighboring block, number 35, may be used as the quadratic transform on 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 the 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 necessary for scanning quantized transformed coefficients of the residual signal of the current block (eg, a diagonal direction, a horizontal direction, and a vertical direction indicating a scanning order) Encoding/decoding of at least one scanning order index among vertical directions may be omitted.

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

As an example, the primary transform and the secondary transform of the neighboring block having the same intra prediction mode as the current block are applied to the current block, or the primary transform and scanning order of the neighboring block or the secondary transform and scanning order of the neighboring block Can be applied to the current block. Alternatively, it is also possible to apply all of the primary transform, secondary transform, and scanning order of a neighboring block 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 in the vicinity of the current block, encoding information of the current block may be derived based on priorities between 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 the left neighboring block It can be derived based on the encoding information of the block.

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

If there is no neighboring block having the same intra prediction mode as the current block, encoding information for the residual signal of the current block may be entropy-encoded/decoded ( S1803 ). For example, when a neighboring block having the same intra prediction mode as the current block does not exist, transform information (or transform index) for the primary transform of the current block, transform information for the secondary transform (or transform index), or At least one of information about the scanning order (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 in which the first encoding information for the residual signal is the same as that of the current block. Here, the first encoding information and the second encoding information may include at least one of information on primary transformation, information on secondary transformation, and a scanning order.

For example, when at least one neighboring block using the same primary transform as the primary transform determined for the current block exists, the secondary transform of the current block is a secondary transform applied to the neighboring block using the same primary transform as the current block. It can be set to transform. In this case, encoding/decoding of encoding information required for secondary transformation of the residual signal for the current block may be omitted. For example, it is assumed that the first-order transformation of the residual signal of the current block is determined as DCT-V in the horizontal direction and DST-VII in the vertical direction. If one or more primary transformations among neighboring blocks of the current block are determined to be DCT-V in the horizontal direction and DST-VII in the vertical direction, the secondary transformation of the neighboring blocks to which the same primary transformation as the current block is applied is currently performed. It can be applied as a quadratic transformation of blocks.

Alternatively, the scanning order of neighboring blocks using the same primary transformation as the primary transformation 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 the neighboring block 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 second transform or the scanning order of the current block is derived from the neighboring block using the same primary transform as the current block, but the neighboring block using the same quadratic transform as the current block Deriving at least one of the primary transformation or scanning order of the current block from the block, or deriving at least one of the primary transformation or the secondary transformation of the current block from a neighboring block using the same scanning order as the current block is also possible.

The second encoding information of the current block may be derived from a neighboring block in which the intra prediction mode and the first encoding information are the same as those of the current block.

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

Alternatively, the scanning order of neighboring blocks in which the intra prediction mode and the first-order transform are the same as those of the current block may be applied as the scanning order of the current block. Alternatively, the intra-prediction mode and the primary transform may apply to the current block the secondary transform and the scanning order of the neighboring block in the same as 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 to this, at least one of the primary transform and the scanning order of the current block is derived from the neighboring block having the same intra prediction mode as the current block and using the same quadratic 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 a 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 encoded 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, in order to derive motion information of the current block, a neighboring block to be merged with the current block may be determined (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 in the merge candidate list. Here, the neighboring blocks of the current block may include not only neighboring blocks spatially adjacent to the current block, but also temporally adjacent neighboring blocks to the current block.

When the neighboring block to be merged with the current block is determined, encoding information on the residual signal of the neighboring block merged with the current block may be derived as encoding information on the residual signal of the current block ( S1903 ). For example, at least one of primary transformation, secondary transformation, and scanning order of the current block may be set to be the same as at least one of primary transformation, secondary transformation, and scanning order of a neighboring block 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 the same motion information as 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 image index, and a reference picture direction.

When there is a neighboring block having the same motion information as the motion information of the current block, the encoding information for the residual signal of the neighboring block having the same motion information as the current block can be derived as the encoding information for the residual signal of the current block. There is (S1905). As an example, at least one of the primary transformation, secondary transformation, and scanning order of the current block may include primary transformation of a neighboring block in which at least one of a motion vector, a reference image index, and a reference picture direction of the current block is the same as the current block; It may be set equal to at least one of the secondary transformation or the scanning order.

If there is no neighboring block having the same motion information as the current block, encoding information for the residual signal of the current block may be entropy-encoded/decoded (S1906). For example, when a neighboring block having the same motion information as the current block does not exist, transform information (or transform index) for the primary transform, transform information (or transform index) for the secondary transform, or scanning order of the current block At least one of information (or a scanning index) for ? may be entropy-encoded/decoded.

In the example shown in FIG. 19 , it is illustrated that a neighboring block from which encoding information for a residual signal of the current block is 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 , only when the inter prediction mode of the current block is the merge mode, encoding information for the residual signal of the current block may be derived from a neighboring block. Alternatively, it is also possible to derive encoding information of the current block from a neighboring block having the same motion information as that of 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 block on the condition that the motion information of the current block and the motion information 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 in which the motion information and the first encoding information for the residual signal are the same as the current block.

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

The above-described encoding information such as the primary transformation, the secondary transformation, or the scanning order includes 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 transform 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 a transform type (eg, DCT-II) most frequently used to transform 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), it means that a predefined transform is applied to the residual signal. It may mean that a conversion type other than the type is applied. Alternatively, the information is configured as a flag of two or more bits to indicate whether a transformation type predefined for the primary transformation is used through the first bit, and the transformation predefined for the secondary transformation through the second bit It may 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 any one of the residual transform types may be encoded. Here, the residual transform type may indicate a transform type remaining except for a predefined transform type 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 represent DCT-V, 2 may represent DCT-VIII, 3 may represent DST-I, and 4 may represent DST-VII.

The index information may indicate a combination of transform types for the horizontal direction and the vertical direction of the residual signal. That is, the 1D transformation type for the horizontal/vertical direction may be determined by one piece of index information. For example, when TM idx is 1 in a state in which the TM flag is 1, a transform type combination mapped to TM idx 1 may be determined as a transform type for the current block in horizontal and vertical directions. 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 direction transformation type and the vertical direction transformation type of the current block, respectively. have.

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 a residual type may be derived from a neighboring block 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 any one of a residual transform type may be derived from a neighboring block of the current block have.

As an example, at least one of the TM flag and TM idx of the current block may be derived as the same value as that of a neighboring block of the current block.

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

For example, any one of a residual transform type or information (TM flag) indicating whether a predefined transform type for the current block is applied from a neighboring block used for intra prediction or inter prediction of the current block At least one of the 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 configured in consideration of at least one of a TM flag and a TM idx. Merge candidates having different values of at least one of TM flag and TM idx may be included in the newly constructed merge candidate list. As an example, the merge candidate list may be configured so that the first merge candidate and the second merge candidate have the same motion information, but have 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 may be encoded/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 or more neighboring blocks 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 is first set to 1 according to a predetermined neighboring block scan order, or may be a block at a predefined position.

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

In addition, the merge candidate list may be generated based on the transform information on the current block separately from the merge candidate list generated based on the motion information. For example, a merge candidate list generated based on motion information of a neighboring block is defined as a 'first merge candidate list', and a merge candidate list generated based on transformation information of a neighboring block is called 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, whereas 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 may indicate whether the scanning order of the current block is the same as a predefined scanning order, and the Scan idx may be information indicating any 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 in a signaling block within a picture or a slice currently being encoded/decoded. Here, the signaling block may mean an area having a small size with respect to at least one of horizontal and vertical resolutions of the current picture or the current slice. That is, the signaling block may be defined as a predetermined region having a size smaller than that of the current picture or the current slice.

Information on the signaling block may be transmitted through at least one of a sequence unit, a picture unit, and a slice header. For example, at least one of the size, shape, and position of the 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 a neighboring block 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, and a scanning order may be identically set. 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 in the 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 the signaling block may be set to have the same encoding information. Here, the predetermined condition may be defined by at least one of the size, shape, and depth of the block. For example, among all blocks included in the signaling block, at least one of a primary transform, a secondary transform, and a scanning order may be identically set for blocks having a predetermined size or smaller (eg, a block having a size of 4x4 or smaller).

The above-described embodiments of obtaining encoding information of the current block may be applied to luminance and chrominance components. In addition, information indicating that at least one of primary transformation, secondary transformation, and scanning has been performed on the residual signal of the current block may be encoded/decoded using at least one method among the above embodiments. In the case of entropy encoding/decoding of the information, a truncated rice binarization method, a K-th order Exp_Golomb binarization method, a limited K-order exponent-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, according to the size and shape of the current block, it may be implicitly induced that the encoding information of the current block is determined by using at least one of the above embodiments.

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) indicating a difference between the encoded motion vector around the current block and the motion vector of the current block to the decoder. have.

The decoder may derive a motion vector candidate of the current block from a motion vector in which encoding around the current block has been completed. Specifically, the decoder may construct a motion vector candidate list (MVP list) after deriving a motion vector candidate from at least one or more from temporal and/or spatial motion vectors that have been decoded for the current block.

The encoder may transmit information (eg, an MVP list index) indicating information on a motion vector predicted value 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 prediction value, and derive a motion vector for the current block by using the motion vector prediction value and the motion vector difference value.

Based on the above description, a method for 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 may be derived (S2001). The 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 , the block B1 adjacent to the top of the current block X, the block A1 adjacent to the left of the current block, the block B0 adjacent to the top right corner of the current block, and the current block The spatial motion vector of the current block may 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 a neighboring block of the current block may be determined as a spatial motion vector candidate of the current block.

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

If the reference image of the neighboring block and the reference image of the current block are different, the movement of the neighboring block using the distance between the current image and the reference image referenced by the neighboring block and the distance between the current image and the reference image referenced by the current block A vector may be scaled to 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). The 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 , outside the co-located block (C) corresponding to the spatially same position as the current block (X) in the 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 position block (C). A temporal motion vector candidate may be sequentially derived from a block at position H and a block at position C3. As an example, when a motion vector can be derived from a block at the H location, a temporal motion vector candidate can be derived from the block at the H location. On the other hand, when the motion vector cannot be derived from the block at the H position, a temporal motion vector candidate can be derived from the block at the C3 position. If the H position or the C3 position block is encoded with intra prediction, a temporal motion vector candidate of the current block cannot be derived.

Not limited to the example shown in FIG. 22 , a co-located picture indicated by the motion information obtained for the current block and a co-located picture included in the co-located picture pointed to by the motion information or around the co-located 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, a temporal motion vector candidate may be obtained in units of sub-blocks smaller than the size of the current block, such as 2x2, 4x4, 8x4, 4x8. The shape of the sub-block may have a square or rectangular shape. In addition, the size or shape of the sub-block may be a fixed one preset in the encoder/decoder, or may be determined dependently on the size or shape of the 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 the motion vector candidate list can include 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. , it is possible to construct a motion vector candidate list. Even if it is possible to derive up to N different spatial motion vector candidates in the process of deriving the spatial motion vector candidates, at least one of the N spatial motion vector candidates is removed from the motion vector candidate list through arbitrary similarity determination. can do. Accordingly, a temporal motion vector candidate may be included in the motion vector candidate list. Here, in the arbitrary similarity determination, even if the spatial motion vectors have different values, when the difference between the motion vectors is not large, the maximum value, the minimum value, the average value, the median value, or an arbitrary weight sum of two or more spatial motion vectors is used. may mean merging them 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 of the spatial motion vector candidates may be removed from the motion vector candidate list in the reverse order of priorities. 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, a temporal motion vector candidate may be included in the motion vector candidate list.

Whether to remove a spatial motion vector candidate from the above-described motion vector candidate list may be determined according to whether a temporal motion vector candidate is used. Also, the number of spatial motion vector candidates 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 available temporal motion vector candidates 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 the motion vector candidate list can include (ie, upward to N+1).

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

When the motion vector prediction value of the current block is determined, the motion vector of the current block may be obtained by using the motion vector difference value (S2005). The motion vector difference value may indicate a difference between the motion vector of the current block and the motion vector predicted value of the current block. A motion vector difference value with respect to 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 the motion vector difference values of the reconstructed blocks encoded by inter prediction around the current block. You may. For example, a second motion vector difference indicating a difference between a motion vector difference indicating a difference between a motion vector and a motion vector prediction value of the current block and a motion vector difference value of reconstructed blocks encoded by inter prediction around the current block A value may 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 with respect to the current block may be encoded using the motion vector difference value of the upper block (Block 1) located at the upper end of the current block.

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

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

As in the above example, 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 as the current block is explicitly transmitted through the bitstream. can be For example, information (eg, MVD index) used to derive a second motion vector candidate from among neighboring blocks of the current block or for identifying a neighboring block having the same motion vector candidate as the current block is transmitted to the decoder through a bitstream. can be

As another example, 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 implicit in the encoder/decoder according to the same process. may be induced. For example, a motion vector difference value of a neighboring block used as a motion vector predictor (MVP) of the current block may be used as a motion vector difference predictor (MVD Predictor) for deriving a second motion vector difference value of the current block. .

When the current block is encoded by bi-prediction, information indicating whether motion vector difference values for the reference picture list 0 (List 0) and the reference picture list 1 (List 1) are the same may be encoded. Here, the same motion vector difference values may mean a case in which the motion vector difference values have the same sign and the same magnitude, or the motion vector difference values have different signs but have the same magnitude. When the motion vector difference values of the reference picture list 0 and the reference picture list 1 are the same, encoding/decoding of the motion vector difference value of any one of the reference picture list 0 and the reference picture list 1 may be omitted.

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

Information on the signaling block may be transmitted through at least one of a sequence unit, a picture unit, and a slice header. For example, at least one of the size, shape, and position of the 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 a neighboring block 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 chrominance signals. For example, in the inter-picture encoding/decoding process, at least one method of obtaining an inter prediction indicator, generating a motion vector candidate list, inducing a motion vector, and performing motion compensation may be differently applied to the luminance signal and the chrominance signal.

The inter-screen encoding/decoding process for the luminance and chrominance signals may be performed in the same manner. For example, in the inter-picture 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 by the encoder and the decoder in the same way. For example, in the inter-picture encoding/decoding process, at least one method of motion vector candidate list derivation, motion vector candidate derivation, motion vector derivation, and motion compensation may be equally applied to the encoder and the decoder. Also, the order of applying the methods may be different in 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. Here, the size may be defined as a minimum size and/or a maximum size to which the embodiments are applied, or may be defined as a fixed size to which the embodiments are applied. Also, in the above embodiments, the first embodiment may be applied in the first size, and the second embodiment may be applied in the second size. That is, the regular embodiments may be complexly applied according to the size. In addition, the above embodiments of the present invention can be applied only when the minimum size or more and the maximum size or less. That is, the above embodiments can be applied only when the block size is included within a certain range.

For example, the above embodiments may be applied only when the size of the encoding/decoding target block is 8x8 or more. For example, the above embodiments may be applied only when the size of the encoding/decoding target block is 16x16 or more. For example, the above embodiments may be applied only when the size of the encoding/decoding target block is 32x32 or more. For example, the above embodiments can be applied only when the size of the encoding/decoding target block is 64x64 or more. For example, the above embodiments can be applied only when the size of the encoding/decoding target block is 128x128 or more. For example, the above embodiments can be applied only when the size of the encoding/decoding target block is 4x4. For example, the above embodiments can be applied only when the size of the encoding/decoding target block is 8x8 or less. For example, the above embodiments can be applied only when the size of the encoding/decoding target block is 16x16 or less. For example, the above embodiments can be applied only when the size of the encoding/decoding target block is 8x8 or more and 16x16 or less. For example, the above embodiments may be applied only when the size of the encoding/decoding target block is 16x16 or more and 64x64 or less.

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 embodiments are applicable, and the embodiments may be applied to a temporal layer specified by the corresponding 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 image is the lowest layer. For example, the above embodiments may be applied only when the temporal layer identifier of the current image is 0. For example, the above embodiments may be applied only when the temporal layer identifier of the current image is 1 or more. For example, the above embodiments may be applied only when the temporal layer of the current image is the highest layer.

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

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

When predicting a motion vector, the motion vector is calculated in 16-pel units, 8-pel units, 4-pel units, integer-pel units, 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 ) unit, 1/32-pixel (1/32-pel) unit, and 1/64-pixel (1/64-pel) unit, the above embodiments of the present invention may be applied. In addition, when performing motion vector prediction, a motion vector may be selectively used for each pixel.

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 Tri-predictive (T)-slice, a prediction block is generated using at least three or more motion vectors, and a weighted sum of the at least three or more 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 quad-predictive (Q)-slice, a prediction block is generated using at least four motion vectors, and a weighted sum of the at least four 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 to inter prediction and motion compensation methods using motion vector prediction, as well as inter prediction and motion compensation methods using skip mode, merge mode, and the like.

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

In the above-described embodiments, the methods are described on the basis of a flowchart 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 of ordinary skill in the art will recognize that the steps shown in the flowchart are not exclusive, other steps may be included, or that one or more steps in the flowchart may be deleted without affecting the scope of the present invention. You will understand.

The above-described embodiments include examples of various aspects. It is not possible to describe every possible combination for representing the various aspects, but one of ordinary skill 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.

The 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 in a computer-readable recording medium. The computer-readable recording medium may include program instructions, data files, data structures, etc. alone or in combination. The program instructions recorded on the computer-readable recording medium may be specially designed and configured for the present invention, or may be known and used by those skilled in the computer software field. Examples of the computer-readable recording medium include hard disks, magnetic media such as floppy disks and magnetic tapes, optical recording media such as CD-ROMs and DVDs, and magneto-optical media such as floppy 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 not only machine language codes such as those generated by a compiler, but also high-level language codes that can be executed by a computer using an interpreter or the like. The hardware device may be configured to operate 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 with specific matters 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 of ordinary skill in the art to which the present invention pertains can devise 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 below but also all modifications equivalently or equivalently to the claims described below belong to the scope of the spirit of the present invention. will do it

Claims (20)

dividing an image to obtain a current block;
partitioning 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 partitioning method; and
generating a reconstructed block using the prediction block,
When the size of the current block exceeds a preset fixed size, the method of dividing the current block is implicitly determined as quadtree division,
When the size of the current block is equal to or less than the predetermined fixed size, the method of dividing the current block is determined as at least one of quadtree division and binary tree division based on signaled information. According to claim 1,
When the size of the current block exceeds the predetermined fixed size, the current block is recursively and repeatedly divided by the quadtree division until the size of the current block is equal to or less than the predetermined fixed size. , video decoding method. delete delete According to claim 1,
If the current block satisfies a predetermined condition, the method of segmenting is not determined by segmenting the binary tree. 6. The method of claim 5,
The predetermined condition is derived based on the size of the current block. According to claim 1,
The step of generating the prediction block comprises:
The method of claim 1, 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. 8. The method of claim 7,
The filtering of the prediction block comprises:
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. 9. The method of claim 8,
The predetermined mode is a planar mode. 9. The method of claim 8,
The reference sample is a sample adjacent to at least one of a left and an upper end of the prediction block. dividing an image to obtain a current block;
partitioning 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 partitioning method; and
encoding the coding block using the prediction block;
When the size of the current block exceeds a preset fixed size, the method of dividing the current block is implicitly determined as quadtree division,
When the size of the current block is less than or equal to the preset fixed size, information on the partitioning method is signaled so that the partitioning method of the current block is determined as at least one of quadtree partitioning and binary tree partitioning. 12. The method of claim 11,
When the size of the current block exceeds the predetermined fixed size, the current block is recursively and repeatedly divided by the quadtree division until the size of the current block is equal to or less than the predetermined fixed size. , an image encoding method. delete delete 12. The method of claim 11,
If the current block satisfies a predetermined condition, the method of segmentation is not determined by the binary tree segmentation. 16. The method of claim 15,
The predetermined condition is derived based on the size of the current block. 12. The method of claim 11,
The step of generating the prediction block comprises:
The method of claim 1, 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. 18. The method of claim 17,
The filtering of the prediction block comprises:
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. 19. The method of claim 18,
The predetermined mode is a planar mode. A non-transitory storage medium including a bitstream, comprising:
dividing an image to obtain a current block;
partitioning 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 partitioning method; and
encoding the coding block using the prediction block;
When the size of the current block exceeds a preset fixed size, the method of dividing the current block is implicitly determined as quadtree division,
When the size of the current block is less than or equal to the preset fixed size, the method of dividing the current block is an image encoding method, characterized in that the information on the dividing method is signaled so that at least one of a quad tree division and a binary tree division is determined. A non-transitory storage medium containing the generated bitstream.

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