WO2020130520A1

WO2020130520A1 - Method and apparatus for processing video signal by using inter prediction

Info

Publication number: WO2020130520A1
Application number: PCT/KR2019/017779
Authority: WO
Inventors: 박내리; 남정학; 장형문
Original assignee: 엘지전자 주식회사
Priority date: 2018-12-16
Filing date: 2019-12-16
Publication date: 2020-06-25

Abstract

An embodiment of the present specification provides a method and an apparatus for processing video data. A method for processing a video signal, according to an embodiment of the present specification, comprises the steps of: obtaining, on the basis of a merge index, a motion vector for inter prediction, of the current block, from at least one neighboring block adjacent to the current block; determining, on the basis of an adaptive motion vector resolution (AMVR) index and a merge motion vector difference (MMVD) distance index, an MMVD offset to be applied to the motion vector; and generating a prediction sample of the current block on the basis of the motion vector, to which the MMVD offset is applied, and a reference picture related with the merge index, wherein the AMVR index is related to one of predetermined MMVD candidate sets on the basis of the resolution of MMVD offset values, and the MMVD distance index indicates a MMVD offset value to be applied to the motion vector in the MMVD candidate sets related to the AMVR index. The MMVD offset value is determined to be within a range set by the AMVR index, so that the amount of bits required to transmit the MMVD distance index can be reduced.

Description

Method and apparatus for processing video signal using inter prediction

An embodiment of the present disclosure relates to a method and apparatus for processing a video signal using inter prediction, and more specifically, performs inter-screen prediction using merge mode to which merge with motion vector difference (MMVD) is applied. It relates to a method and apparatus for.

Compression coding refers to a series of signal processing techniques for transmitting digitized information through a communication line or storing it in a form suitable for a storage medium. Media such as video, image, and audio may be the subject of compression encoding, and a technique for performing compression encoding on an image is referred to as video image compression.

Next-generation video content will have the characteristics of high spatial resolution, high frame rate and high dimensionality of scene representation. In order to process such content, it will bring a huge increase in terms of memory storage, memory access rate and processing power.

Therefore, it is necessary to design a coding tool to process next-generation video content more efficiently. In particular, the video codec standard after the high efficiency video coding (HEVC) standard requires a prediction technique capable of generating prediction samples accurately while using resources more efficiently.

Embodiments of the present specification provide a video signal processing method and apparatus capable of improving the accuracy of a motion vector when applying merge mode.

In addition, an embodiment of the present specification provides a video signal processing method and apparatus capable of reducing signaling overhead in the process of applying a merge with motion vector difference (MMVD) technique.

The technical problems to be achieved in the present specification are not limited to the technical problems mentioned above, and other technical problems that are not mentioned will be clearly understood by those skilled in the art from the description below. Will be able to.

A method for processing a video signal according to an embodiment of the present disclosure includes obtaining a motion vector for inter-frame prediction of the current block from at least one neighboring block adjacent to the current block based on a merge index, and AMVR ( determining an MMVD offset applied to the motion vector based on an adaptive motion vector resolution (MMVD) index and a merge with motion vector difference (MMVD) length index; and a reference picture related to the motion vector and the merge index to which the MMVD offset is applied. Generating a prediction sample of the current block based on the AMVR index being associated with one of a predetermined set of MMVD candidates based on the resolution of MMVD offset values, the MMVD length index, and the AMVR index. The MMVD offset value to be applied to the motion vector may be indicated in a set of MMVD candidates associated with.

In one embodiment, generating the prediction sample of the current block includes: obtaining an MMVD direction index indicating the sign of the MMVD offset, and applying a code corresponding to the MMVD direction index to the MMVD offset. And adding the MMVD offset to which the sign is applied to the motion vector.

In one embodiment, the AMVR index may be determined based on a resolution of a motion vector difference (MVD) applied to a motion vector of a neighboring block associated with the merge index.

In one embodiment, the AMVR index may be updated based on the size of the MMVD offset indicated by the MMVD length index, and the updated AMVR index may be reused as the AMVR index of a block processed after the current block. Can. For example, if the MMVD offset is greater than or equal to a reference value, the AMVR index is determined to indicate the first set of MMVDs. If the size of the MMVD offset is less than the reference value, the AMVR index sets the second MMVD set index. It is determined to indicate, and the first MMVD set may have a value greater than the MMVD offset of the second MMVD set for the same MMVD length index.

In one embodiment, a range of the MMVD offset applied to the motion vector may be determined based on the resolution of the AMVR index and the position coordinate indicated by the motion vector.

In one embodiment, a range of the MMVD offset applied to the motion vector may be determined based on the AMVR index and the size of the current block.

According to an embodiment of the present specification, accuracy of a motion vector may be improved by performing prediction using a merge mode to which a merge with motion vector difference (MMVD) technique is applied.

In addition, according to an embodiment of the present disclosure, in the course of applying the MMVD technique, a video signal processing method and apparatus capable of reducing signaling overhead by using an MMVD range index indicating a certain MMVD length range is provided. do.

The effects obtained in the present specification are not limited to the above-mentioned effects, and other effects not mentioned may be clearly understood by those skilled in the art from the following description. .

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are included as part of the detailed description to aid understanding of the present specification, provide embodiments of the present specification and describe the technical features of the present specification together with the detailed description.

1 shows an example of a video coding system according to an embodiment of the present specification.

2 shows a schematic block diagram of an encoding apparatus for encoding a video/image signal according to an embodiment of the present specification.

3 is an embodiment of the present specification, and shows a schematic block diagram of a decoding apparatus for decoding a video signal.

4 shows an example of a structural diagram of a content streaming system according to an embodiment of the present specification.

5 shows an example of a block diagram of an apparatus for processing a video signal according to an embodiment of the present specification.

6 is an example of a block partitioning structure according to an embodiment of the present disclosure, FIG. 6A is a quad tree (QT), FIG. 3B is a binary tree (BT), FIG. 3C is a ternary tree (TT), and FIG. 3D is an asymmetric tree (AT) ).

7 and 8 illustrate a video/video encoding procedure based on inter prediction and an inter prediction unit in an encoding device.

9 and 10 illustrate a video/video decoding procedure based on inter prediction and an inter prediction unit in a decoding device.

11 shows an example of a spatial merge candidate configuration for the current block.

12 shows an example of a flowchart for configuring a merge candidate list according to an embodiment of the present specification.

13 shows an example of a flowchart for constructing a prediction candidate list (MVP candidate list).

14 shows an example of an MMVD discovery process according to an embodiment of the present specification.

15 shows an example of a flowchart for performing prediction using a merge mode to which a merge with motion vector difference (MMVD) technique according to an embodiment of the present disclosure is applied.

16 shows an example of triangular prediction units according to an embodiment of the present specification.

Hereinafter, preferred embodiments according to the present specification will be described in detail with reference to the accompanying drawings. DETAILED DESCRIPTION The following detailed description, together with the accompanying drawings, is intended to describe exemplary embodiments of the present specification and is not intended to represent the only embodiments in which the present specification may be practiced. The following detailed description includes specific details to provide a thorough understanding of the specification. However, one of ordinary skill in the art knows that the present specification can be practiced without these specific details.

In some cases, in order to avoid obscuring the concept of the present specification, well-known structures and devices may be omitted, or block diagrams centering on core functions of each structure and device may be illustrated.

In addition, the terms used in the present specification have been selected as general terms that are currently widely used as much as possible, but in specific cases, the terms are arbitrarily selected by the applicant. In such a case, since the meaning is clearly described in the detailed description of the relevant part, it should not be interpreted simply by the name of the term used in the description of this specification, and it is to be clarified that the meaning of the term should be understood and interpreted. .

Specific terms used in the following description are provided to help understanding of the present specification, and the use of these specific terms may be changed to other forms without departing from the technical spirit of the present specification. For example, signals, data, samples, pictures, slices, tiles, frames, and blocks may be interpreted by being appropriately substituted in each coding process.

Hereinafter, in the present specification, the term'processing unit' means a unit in which encoding/decoding processing processes such as prediction, transformation, and/or quantization are performed. Also, the processing unit may be interpreted as meaning including a unit for a luminance component and a unit for a chroma component. For example, the processing unit may correspond to a block, a coding unit (CU), a prediction unit (PU), or a transform unit (TU).

Further, the processing unit may be interpreted as a unit for a luminance component or a unit for a color difference component. For example, the processing unit may correspond to a coding tree block (CTB), a coding block (CB), a PU or a transform block (TB) for the luminance component. Alternatively, the processing unit may correspond to CTB, CB, PU or TB for the color difference component. In addition, the present invention is not limited thereto, and the processing unit may be interpreted to include a unit for a luminance component and a unit for a color difference component.

In addition, the processing unit is not necessarily limited to a square block, and may be configured in a polygonal shape having three or more vertices.

In addition, in the present specification, pixels, pixels, or coefficients (transformation coefficients or transformation coefficients that have undergone first-order transformation) are hereinafter collectively referred to as samples. And, using a sample may mean using a pixel value, a pixel value, or a coefficient (a transform coefficient or a transform coefficient that has undergone first-order transformation).

The video coding system can include a source device 10 and a receiving device 20. The source device 10 may transmit the encoded video/video information or data to the receiving device 20 through a digital storage medium or a network in a file or streaming form.

The source device 10 may include a video source 11, an encoding device 12, and a transmitter 13. The receiving device 20 may include a receiver 21, a decoding device 22 and a renderer 23. The encoding device 10 may be called a video/video encoding device, and the decoding device 20 may be called a video/video decoding device. The transmitter 13 may be included in the encoding device 12. The receiver 21 may be included in the decoding device 22. The renderer 23 may include a display unit, and the display unit may be configured as a separate device or an external component.

The video source may acquire a video/image through a capture, synthesis, or generation process of the video/image. The video source may include a video/image capture device and/or a video/image generation device. The video/image capture device may include, for example, one or more cameras, a video/image archive including previously captured video/images, and the like. The video/image generating device may include, for example, a computer, a tablet and a smartphone, and may (electronically) generate a video/image. For example, a virtual video/image may be generated through a computer or the like, and in this case, a video/image capture process may be replaced by a process of generating related data.

The encoding device 12 may encode an input video/image. The encoding apparatus 12 may perform a series of procedures such as prediction, transformation, and quantization for compression and coding efficiency. The encoded data (encoded video/image information) may be output in the form of a bitstream.

The transmitting unit 13 may transmit the encoded video/video information or data output in the form of a bitstream to a receiving unit of a receiving device through a digital storage medium or a network in a file or streaming format. Digital storage media include universal serial bus (USB), secure digital (SD), compact disk (CD), digital video disk (DVD), bluray, hard disk drive (HDD), and solid state drive (SSD). It may include various storage media. The transmission unit 13 may include an element for generating a media file through a predetermined file format, and may include an element for transmission through a broadcast/communication network. The receiver 21 may extract the bitstream and transmit it to the decoding device 22.

The decoding apparatus 22 may decode a video/image by performing a series of procedures such as inverse quantization, inverse transformation, and prediction corresponding to the operation of the encoding apparatus 12.

The renderer 23 may render the decoded video/image. The rendered video/image may be displayed through the display unit.

Referring to FIG. 2, the encoding apparatus 100 includes an image segmentation unit 110, a subtraction unit 115, a conversion unit 120, a quantization unit 130, an inverse quantization unit 140, and an inverse conversion unit 150, It may include an adder 155, a filtering unit 160, a memory 170, an inter prediction unit 180, an intra prediction unit 185, and an entropy encoding unit 190. The inter prediction unit 180 and the intra prediction unit 185 may be collectively referred to as a prediction unit. That is, the prediction unit may include an inter prediction unit 180 and an intra prediction unit 185. The transform unit 120, the quantization unit 130, the inverse quantization unit 140, and the inverse transform unit 150 may be included in a residual processing unit. The residual processing unit may further include a subtraction unit 115. The above-described image segmentation unit 110, subtraction unit 115, conversion unit 120, quantization unit 130, inverse quantization unit 140, inverse conversion unit 150, addition unit 155, filtering unit 160 ), the inter prediction unit 180, the intra prediction unit 185 and the entropy encoding unit 190 may be configured by one hardware component (for example, an encoder or processor) according to an embodiment. Also, the memory 170 may be configured by one hardware component (for example, a memory or digital storage medium) according to an embodiment, and the memory 170 may include a decoded picture buffer (DPB) 175. .

The image division unit 110 may divide the input image (or picture, frame) input to the encoding apparatus 100 into one or more processing units. As an example, the processing unit may be referred to as a coding unit (CU). In this case, the coding unit may be recursively divided according to a quad-tree binary-tree (QTBT) structure from a coding tree unit (CTU) or a largest coding unit (LCU). For example, one coding unit may be divided into a plurality of coding units of a deeper depth based on a quad tree structure and/or a binary tree structure. In this case, for example, a quad tree structure may be applied first, and a binary tree structure may be applied later. Alternatively, a binary tree structure may be applied first. The coding procedure according to the present specification may be performed based on the final coding unit that is no longer split. In this case, the maximum coding unit may be directly used as a final coding unit based on coding efficiency according to image characteristics, or the coding unit may be recursively divided into coding units having a lower depth than optimal, if necessary. The coding unit of the size of can be used as the final coding unit. Here, the coding procedure may include procedures such as prediction, transformation, and reconstruction, which will be described later. As another example, the processing unit may further include a prediction unit (PU) or a transformation unit (TU). In this case, the prediction unit and transform unit may be partitioned or partitioned from the above-described final coding unit, respectively. The prediction unit may be a unit of sample prediction, and the transformation unit may be a unit for deriving a transform coefficient and/or a unit for deriving a residual signal from the transform coefficient.

The unit may be used interchangeably with terms such as a block or area depending on the case. In a general case, the MxN block may represent samples of M columns and N rows or a set of transform coefficients. The sample may generally represent a pixel or a pixel value, and may indicate only a pixel/pixel value of a luma component or only a pixel/pixel value of a saturation component. The sample may be used as a term for one picture (or image) corresponding to a pixel or pel.

The encoding apparatus 100 subtracts a prediction signal (a predicted block, a prediction sample array) output from the inter prediction unit 180 or the intra prediction unit 185 from the input image signal (original block, original sample array) A signal (remaining block, residual sample array) may be generated, and the generated residual signal is transmitted to the converter 120. In this case, as illustrated, a unit that subtracts a prediction signal (a prediction block, a prediction sample array) from an input video signal (original block, original sample array) in the encoding apparatus 100 may be referred to as a subtraction unit 115. The prediction unit may perform prediction on a block to be processed (hereinafter, referred to as a current block) and generate a predicted block including prediction samples for the current block. The prediction unit may determine whether intra prediction is applied or inter prediction is applied in units of blocks or CUs. The prediction unit may generate various pieces of information about prediction, such as prediction mode information, as described later in the description of each prediction mode, and transmit them to the entropy encoding unit 190. The prediction information may be encoded by the entropy encoding unit 190 and output in the form of a bitstream.

The intra prediction unit 185 may predict the current block by referring to samples in the current picture. The referenced samples may be located in the neighborhood of the current block or may be located apart depending on a prediction mode. In intra prediction, prediction modes may include a plurality of non-directional modes and a plurality of directional modes. The non-directional mode may include, for example, a DC mode and a planar mode (planar mode). The directional mode may include, for example, 33 directional prediction modes or 65 directional prediction modes according to the degree of detail of the prediction direction. However, this is an example, and more or less directional prediction modes may be used depending on the setting. The intra prediction unit 185 may determine a prediction mode applied to the current block by using a prediction mode applied to neighboring blocks.

The inter prediction unit 180 may derive a predicted block for the current block based on a reference block (reference sample array) specified by a motion vector on the reference picture. At this time, to reduce the amount of motion information transmitted in the inter prediction mode, motion information may be predicted in units of blocks, subblocks, or samples based on the correlation of motion information between a neighboring block and a current block. The motion information may include a motion vector and a reference picture index. The motion information may further include inter prediction direction (L0 prediction, L1 prediction, Bi prediction, etc.) information. In the case of inter prediction, the neighboring block may include a spatial neighboring block existing in the current picture and a temporal neighboring block present in the reference picture. The reference picture including the reference block and the reference picture including the temporal neighboring block may be the same or different. The temporal neighboring block may be referred to by a name such as a collocated reference block or a colCU, and a reference picture including a temporal neighboring block may also be called a collocated picture (colPic). . For example, the inter prediction unit 180 constructs a motion information candidate list based on neighboring blocks, and generates information indicating which candidates are used to derive the motion vector and/or reference picture index of the current block. can do. Inter prediction may be performed based on various prediction modes. For example, in the case of the skip mode and the merge mode, the inter prediction unit 180 may use motion information of neighboring blocks as motion information of the current block. In the skip mode, unlike the merge mode, the residual signal may not be transmitted. In the motion vector prediction (MVP) mode, the motion vector of the current block is obtained by using the motion vector of the neighboring block as a motion vector predictor and signaling a motion vector difference. I can order.

The prediction signal generated by the inter prediction unit 180 or the intra prediction unit 185 may be used to generate a reconstructed signal or may be used to generate a residual signal.

The transform unit 120 may generate transform coefficients by applying a transform technique to the residual signal. For example, the transformation technique may include at least one of a discrete cosine transform (DCT), a discrete sine transform (DST), a Karhunen-Loeve transform (KLT), a graph-based transform (GBT), or a conditionally non-linear transform (CNT). It can contain. Here, GBT refers to a transformation obtained from this graph when it is said to graphically represent relationship information between pixels. CNT means a transform obtained by generating a prediction signal using all previously reconstructed pixels and based on it. Further, the transform process may be applied to pixel blocks having the same size of a square, or may be applied to blocks of variable sizes other than squares.

The quantization unit 130 quantizes the transform coefficients and transmits them to the entropy encoding unit 190, and the entropy encoding unit 190 encodes the quantized signal (information about quantized transform coefficients) and outputs it as a bitstream. have. Information about the quantized transform coefficients may be called residual information. The quantization unit 130 may rearrange block-type quantized transform coefficients into a one-dimensional vector form based on a coefficient scan order, and the quantized transform based on the one-dimensional vector form quantized transform coefficients Information about coefficients may be generated. The entropy encoding unit 190 may perform various encoding methods such as exponential Golomb (CAVLC), context-adaptive variable length coding (CAVLC), and context-adaptive binary arithmetic coding (CABAC). The entropy encoding unit 190 may encode information necessary for video/image reconstruction (eg, values of syntax elements, etc.) together with the quantized transform coefficients together or separately. The encoded information (eg, video/video information) may be transmitted or stored in the unit of a network abstraction layer (NAL) unit in the form of a bitstream. The bitstream can be transmitted over a network or stored on a digital storage medium. Here, the network may include a broadcasting network and/or a communication network, and the digital storage medium may include various storage media such as USB, SD, CD, DVD, Blu-ray, HDD, SSD. The signal output from the entropy encoding unit 190 may be configured as an internal/external element of the encoding apparatus 100 by a transmitting unit (not shown) and/or a storing unit (not shown) for storing, or the transmitting unit It may be a component of the entropy encoding unit 190.

The quantized transform coefficients output from the quantization unit 130 may be used to generate a prediction signal. For example, the residual signal may be reconstructed by applying inverse quantization and inverse transform through the inverse quantization unit 140 and the inverse transform unit 150 in the loop to the quantized transform coefficients. The adder 155 adds the reconstructed residual signal to the predicted signal output from the inter predictor 180 or the intra predictor 185, so that the reconstructed signal (restored picture, reconstructed block, reconstructed sample array) Can be generated. If there is no residual for the block to be processed, such as when the skip mode is applied, the predicted block may be used as a reconstructed block. The adding unit 155 may be referred to as a restoration unit or a restoration block generation unit. The reconstructed signal may be used for intra prediction of a next processing target block in a current picture, or may be used for inter prediction of a next picture through filtering as described below.

The filtering unit 160 may improve subjective/objective image quality by applying filtering to the reconstructed signal. For example, the filtering unit 160 may generate a modified reconstructed picture by applying various filtering methods to the reconstructed picture, and may transmit the modified reconstructed picture to the decoded picture buffer 170. Various filtering methods may include, for example, deblocking filtering, sample adaptive offset, adaptive loop filter, and bilateral filter. The filtering unit 160 may generate various pieces of information regarding filtering as described later in the description of each filtering method and transmit them to the entropy encoding unit 190. The filtering information may be encoded by the entropy encoding unit 190 and output in the form of a bitstream.

The modified reconstructed picture transmitted to the decoded picture buffer 170 may be used as a reference picture in the inter prediction unit 180. When the inter prediction is applied through the encoding apparatus 100, prediction mismatches in the encoding apparatus 100 and the decoding apparatus 200 may be avoided, and encoding efficiency may be improved.

The decoded picture buffer 170 may store the modified reconstructed picture for use as a reference picture in the inter prediction unit 180.

Referring to FIG. 3, the decoding apparatus 200 includes an entropy decoding unit 210, an inverse quantization unit 220, an inverse conversion unit 230, an addition unit 235, a filtering unit 240, a memory 250, and an inter It may be configured to include a prediction unit 260 and the intra prediction unit 265. The inter prediction unit 260 and the intra prediction unit 265 may be collectively referred to as a prediction unit. That is, the prediction unit may include an inter prediction unit 180 and an intra prediction unit 185. The inverse quantization unit 220 and the inverse conversion unit 230 may be collectively referred to as a residual processing unit. That is, the residual processing unit may include an inverse quantization unit 220 and an inverse conversion unit 230. The entropy decoding unit 210, the inverse quantization unit 220, the inverse transform unit 230, the addition unit 235, the filtering unit 240, the inter prediction unit 260, and the intra prediction unit 265, according to the embodiment It can be configured by one hardware component (eg, a decoder or processor). Also, the decoded picture buffer 250 may be implemented by one hardware component (eg, a memory or digital storage medium) according to an embodiment. Also, the memory 250 may include the DPB 175 and may be configured by a digital storage medium.

When a bitstream including video/image information is input, the decoding apparatus 200 may restore an image in response to a process in which the video/image information is processed by the encoding apparatus 100 of FIG. 2. For example, the decoding apparatus 200 may perform decoding using a processing unit applied by the encoding apparatus 100. Thus, in decoding, the processing unit may be, for example, a coding unit, and the coding unit may be divided according to a quad tree structure and/or a binary tree structure from a coding tree unit or a largest coding unit. Then, the decoded video signal decoded and output through the decoding apparatus 200 may be reproduced through the reproduction apparatus.

The decoding apparatus 200 may receive the signal output from the encoding apparatus 100 of FIG. 2 in the form of a bitstream, and the received signal may be decoded through the entropy decoding unit 210. For example, the entropy decoding unit 210 may parse the bitstream to derive information (eg, video/image information) necessary for image reconstruction (or picture reconstruction). For example, the entropy decoding unit 210 decodes information in a bitstream based on a coding method such as exponential Golomb coding, CAVLC, or CABAC, and quantizes a value of a syntax element necessary for image reconstruction and a transform coefficient for residual. Can output More specifically, the CABAC entropy decoding method receives bins corresponding to each syntax element in a bitstream, and decodes syntax information of the target syntax element and surrounding and decoded blocks, or the symbol/bin decoded in the previous step. The context model is determined using the information of, and the probability of occurrence of the bin is predicted according to the determined context model to perform arithmetic decoding of the bin to generate a symbol corresponding to the value of each syntax element. have. At this time, the CABAC entropy decoding method may update the context model using the decoded symbol/bin information for the next symbol/bin context model after determining the context model. Among the information decoded by the entropy decoding unit 210, information regarding prediction is provided to a prediction unit (inter prediction unit 260 and intra prediction unit 265), and the entropy decoding unit 210 performs entropy decoding. The dual value, that is, quantized transform coefficients and related parameter information, may be input to the inverse quantization unit 220. Also, information related to filtering among information decoded by the entropy decoding unit 210 may be provided to the filtering unit 240. Meanwhile, a receiving unit (not shown) receiving a signal output from the encoding apparatus 100 may be further configured as an internal/external element of the decoding apparatus 200, or the receiving unit may be a component of the entropy decoding unit 210. It might be.

The inverse quantization unit 220 may output transform coefficients by inverse quantizing the quantized transform coefficients. The inverse quantization unit 220 may rearrange the quantized transform coefficients in a two-dimensional block form. In this case, reordering may be performed based on the coefficient scan order performed by the encoding apparatus 100. The inverse quantization unit 220 may perform inverse quantization on the quantized transform coefficients using a quantization parameter (for example, quantization step size information), and obtain a transform coefficient.

The inverse transform unit 230 may output a residual signal (residual block, residual sample array) by applying an inverse transform to the transform coefficient.

The prediction unit may perform prediction on the current block and generate a predicted block including prediction samples for the current block. The prediction unit may determine whether intra prediction or inter prediction is applied to the current block based on information about prediction output from the entropy decoding unit 210, and may determine a specific intra/inter prediction mode.

The intra prediction unit 265 may predict the current block by referring to samples in the current picture. The referenced samples may be located in the neighborhood of the current block or spaced apart according to the prediction mode. In intra prediction, prediction modes may include a plurality of non-directional modes and a plurality of directional modes. The intra prediction unit 265 may determine a prediction mode applied to the current block using a prediction mode applied to neighboring blocks.

The inter prediction unit 260 may derive a predicted block for the current block based on a reference block (reference sample array) specified by a motion vector on the reference picture. In this case, in order to reduce the amount of motion information transmitted in the inter prediction mode, motion information may be predicted on a block, subblock, or sample basis based on the correlation of motion information between a neighboring block and a current block. The motion information may include a motion vector and a reference picture index. The motion information may further include information on the inter prediction direction (L0 prediction, L1 prediction, Bi prediction, etc.). In the case of inter prediction, the neighboring block may include a spatial neighboring block existing in the current picture and a temporal neighboring block present in the reference picture. For example, the inter prediction unit 260 may construct a motion information candidate list based on neighboring blocks, and derive a motion vector and/or reference picture index of the current block based on the received candidate selection information. Inter prediction may be performed based on various prediction modes, and information on prediction may include information indicating a mode of inter prediction for a current block.

The adding unit 235 adds the obtained residual signal to the prediction signal (predicted block, prediction sample array) output from the inter prediction unit 260 or the intra prediction unit 265, thereby restoring a signal (restored picture, reconstructed block). , A reconstructed sample array). If there is no residual for the block to be processed, such as when the skip mode is applied, the predicted block may be used as a reconstructed block.

The adding unit 235 may be called a restoration unit or a restoration block generation unit. The generated reconstructed signal may be used for intra prediction of a next processing target block in a current picture, or may be used for inter prediction of a next picture through filtering as described below.

The filtering unit 240 may improve subjective/objective image quality by applying filtering to the reconstructed signal. For example, the filtering unit 240 may generate a modified reconstructed picture by applying various filtering methods to the reconstructed picture, and may transmit the modified reconstructed picture to the decoded picture buffer 250. Various filtering methods may include, for example, deblocking filtering, sample adaptive offset (SAO), adaptive loop filter (ALF), bilateral filter, and the like.

The corrected reconstructed picture transmitted to the decoded picture buffer 250 may be used as a reference picture by the inter prediction unit 260.

In the present specification, the embodiments described in the filtering unit 160, the inter prediction unit 180, and the intra prediction unit 185 of the encoding device 100 are respectively the filtering unit 240 and the inter prediction unit 260 of the decoding device. ) And the intra prediction unit 265 may be applied to the same or corresponding.

The content streaming system to which the present specification is applied may largely include an encoding server 410, a streaming server 420, a web server 430, a media storage 440, a user device 450, and a multimedia input device 460. have.

The encoding server 410 may compress the content input from multimedia input devices such as a smartphone, camera, camcorder, etc. into digital data to generate a bitstream and transmit it to the streaming server 420. As another example, when multimedia input devices 460 such as a smartphone, camera, and camcorder directly generate a bitstream, the encoding server 410 may be omitted.

The bitstream may be generated by an encoding method or a bitstream generation method to which the present specification is applied, and the streaming server 420 may temporarily store the bitstream in the process of transmitting or receiving the bitstream.

The streaming server 420 transmits multimedia data to the user device 450 based on a user request through the web server 430, and the web server 430 serves as an intermediary to inform the user of the service. When a user requests a desired service from the web server 430, the web server 430 delivers it to the streaming server 420, and the streaming server 420 transmits multimedia data to the user. At this time, the content streaming system may include a separate control server, in which case the control server serves to control commands/responses between devices in the content streaming system.

Streaming server 420 may receive content from media storage 440 and/or encoding server 410. For example, the streaming server 420 may receive content in real time from the encoding server 410. In this case, in order to provide a smooth streaming service, the streaming server 420 may store the bitstream for a predetermined time.

For example, the user device 450 includes a mobile phone, a smart phone, a laptop computer, a terminal for digital broadcasting, a personal digital assistants (PDA), a portable multimedia player (PMP), navigation, a slate PC ( slate PC), tablet PC (tablet PC), ultrabook (ultrabook), wearable device (wearable device, for example, a smart watch (smartwatch), glass type (smart glass), HMD (head mounted display), digital TVs, desktop computers, and digital signage.

Each server in the content streaming system can be operated as a distributed server, and in this case, data received from each server can be distributed.

5 shows an example of a block diagram of an apparatus for processing a video signal according to an embodiment of the present specification. The video signal processing apparatus of FIG. 5 may correspond to the encoding apparatus 100 of FIG. 2 or the decoding apparatus 200 of FIG. 3.

The video signal processing apparatus 500 according to the embodiment of the present specification may include a memory 520 for storing a video signal, and a processor 510 for processing a video signal while being combined with the memory.

The processor 510 according to an embodiment of the present disclosure may be configured with at least one processing circuit for processing a video signal, and may process a video signal by executing instructions for encoding or decoding the video signal. That is, the processor 510 may encode the original video signal or decode the encoded video signal by executing the encoding or decoding methods described below.

6 is an example of a block division structure according to an embodiment of the present disclosure, FIG. 6A is a QT (quad tree, hereinafter referred to as'QT'), and FIG. 3B is a BT (binary tree, hereinafter referred to as'BT') , FIG. 3C shows an example of block division structures by an TT (ternary tree, hereinafter referred to as'TT') and FIG. 3D, an AT (asymmetric tree, hereinafter referred to as'TT').

In video coding, one block can be divided based on QT. Also, one sub-block divided by QT may be further divided recursively using QT. A leaf block that is no longer QT split may be split by at least one of BT, TT, or AT. BT may have two types of splitting: horizontal BT (2NxN, 2NxN) and vertical BT (Nx2N, Nx2N). The TT may have two types of splitting: horizontal TT (2Nx1/2N, 2NxN, 2Nx1/2N) and vertical TT (1/2Nx2N, Nx2N, 1/2Nx2N). AT is horizontal-up AT (2Nx1/2N, 2Nx3/2N), horizontal-down AT (2Nx3/2N, 2Nx1/2N), vertical-left AT (1/2Nx2N, 3/2Nx2N), vertical-right AT (3 /2Nx2N, 1/2Nx2N). Each BT, TT, AT can be further divided recursively using BT, TT, AT.

6A shows an example of QT segmentation. Block A can be divided into four sub-blocks (A0, A1, A2, A3) by QT. Sub-block A1 may be divided into four sub-blocks (B0, B1, B2, and B3) again by QT.

6B shows an example of BT segmentation. Block B3, which is no longer divided by QT, may be divided into vertical BT (C0, C1) or horizontal BT (D0, D1). As in the block C0, each sub-block may be further recursively divided in the form of horizontal BT (E0, E1) or vertical BT (F0, F1).

6C shows an example of TT segmentation. Block B3, which is no longer divided by QT, may be divided into vertical TT (C0, C1, C2) or horizontal TT (D0, D1, D2). As in block C1, each sub-block may be further recursively divided in the form of horizontal TT (E0, E1, E2) or vertical TT (F0, F1, F2).

6D shows an example of AT partitioning. Block B3, which is no longer divided by QT, may be divided into vertical AT (C0, C1) or horizontal AT (D0, D1). As in block C1, each sub-block may be further recursively divided in the form of horizontal AT (E0, E1) or vertical TT (F0, F1).

On the other hand, BT, TT, AT partitioning can be combined. For example, a sub-block divided by BT can be divided by TT or AT. In addition, the sub-block divided by TT can be divided by BT or AT. The sub-block divided by AT can be divided by BT or TT. For example, after horizontal BT division, each sub-block may be divided into vertical BT, or after vertical BT division, each sub-block may be divided into horizontal BT. The two types of division methods have different division order, but the shape of the final division is the same.

In addition, when a block is divided, the order in which blocks are searched can be variously defined. In general, a search is performed from left to right, from top to bottom, and searching for blocks means an order of determining whether to divide additional blocks of each divided sub-block, or when a block is no longer divided, each sub It may mean a coding order of blocks, or a search order when sub-blocks refer to information of other neighboring blocks.

The encoding apparatus 100 performs inter prediction on the current block (S710). The encoding apparatus 100 may derive the inter prediction mode and motion information of the current block, and generate prediction samples of the current block. Here, the procedure for determining the inter prediction mode, deriving motion information, and generating prediction samples may be performed simultaneously, or one procedure may be performed before the other procedure. For example, the inter prediction unit 180 of the encoding apparatus 100 may include a prediction mode determination unit 181, a motion information derivation unit 182, and a prediction sample derivation unit 183, and the prediction mode determination unit The prediction mode for the current block may be determined at 181, motion information of the current block may be derived from the motion information derivation unit 182, and prediction samples of the current block may be derived from the prediction sample derivation unit 183. For example, the inter prediction unit 180 of the encoding apparatus 100 searches a block similar to the current block in a certain area (search area) of reference pictures through motion estimation, and It is possible to derive a reference block with a difference of less than or equal to a certain standard. Based on this, a reference picture index indicating a reference picture in which the reference block is located may be derived, and a motion vector may be derived based on a position difference between the reference block and the current block. The encoding apparatus 100 may determine a mode applied to a current block among various prediction modes. The encoding apparatus 100 may compare the RD cost for various prediction modes and determine the optimal prediction mode for the current block.

For example, when the skip mode or the merge mode is applied to the current block, the encoding apparatus 100 configures a merge candidate list, which will be described later, and the current block among the reference blocks indicated by the merge candidates included in the merge candidate list. A reference block in which the difference from the current block is less than or equal to a certain criterion can be derived. In this case, a merge candidate associated with the derived reference block is selected, and merge index information indicating the selected merge candidate may be generated and signaled to the decoding apparatus 200. Motion information of the current block may be derived using the motion information of the selected merge candidate.

As another example, when the (A)MVP mode is applied to the current block, the encoding apparatus 100 configures the (A)MVP candidate list, which will be described later, and (A) the motion vector predictor (MVP) candidates included in the MVP candidate list. The motion vector of the selected MVP candidate can be used as the MVP of the current block. In this case, for example, a motion vector indicating a reference block derived by the above-described motion estimation may be used as a motion vector of the current block, and among the MVP candidates, a motion vector having the smallest difference from the motion vector of the current block may be used. The MVP candidate to have may be the selected MVP candidate. A motion vector difference (MVD), which is a difference obtained by subtracting MVP from the motion vector of the current block, may be derived. In this case, information about the MVD may be signaled to the decoding device 200. In addition, when the (A)MVP mode is applied, the value of the reference picture index may be configured and reference signal index information may be separately signaled to the decoding apparatus 200.

The encoding apparatus 100 may derive residual samples based on the predicted samples (S720 ). The encoding apparatus 100 may derive residual samples through comparison of original samples and prediction samples of the current block.

The encoding apparatus 100 encodes video information including prediction information and residual information (S730). The encoding apparatus 100 may output encoded image information in the form of a bitstream. The prediction information is information related to a prediction procedure and may include prediction mode information (eg, skip flag, merge flag, or mode index) and motion information. The motion information may include candidate selection information (eg, merge index, mvp flag, or mvp index) that is information for deriving a motion vector. In addition, the motion information may include information on the MVD and/or reference picture index information. Also, the motion information may include information indicating whether L0 prediction, L1 prediction, or bi prediction is applied. The residual information is information about residual samples. The residual information may include information about quantized transform coefficients for residual samples.

The output bitstream may be stored in a (digital) storage medium and transmitted to a decoding device, or may be delivered to a decoding device through a network.

On the other hand, as described above, the encoding apparatus may generate a reconstructed picture (including reconstructed samples and reconstructed blocks) based on the reference samples and the residual samples. This is because the encoding apparatus 100 derives the same prediction results as those performed by the decoding apparatus 200, and thus, it is possible to increase coding efficiency. Accordingly, the encoding apparatus 100 may store a reconstructed picture (or reconstructed samples, reconstructed block) in a memory and use it as a reference picture for inter prediction. As described above, an in-loop filtering procedure may be further applied to the reconstructed picture.

The decoding apparatus 200 may perform an operation corresponding to an operation performed by the encoding apparatus 100. The decoding apparatus 200 may perform prediction on the current block and derive prediction samples based on the received prediction information.

Specifically, the decoding apparatus 200 may determine a prediction mode for the current block based on the received prediction information (S910). The decoding apparatus 200 may determine which inter prediction mode is applied to the current block based on the prediction mode information in the prediction information.

For example, the decoding apparatus 200 may determine whether a merge mode is applied to the current block or (A)MVP mode is determined based on a merge flag. Alternatively, the decoding apparatus 200 may select one of various inter prediction mode candidates based on the mode index. The inter prediction mode candidates may include skip mode, merge mode and/or (A) MVP mode, or various inter prediction modes described below.

The decoding apparatus 200 derives motion information of the current block based on the determined inter prediction mode (S920). For example, when the skip mode or the merge mode is applied to the current block, the decoding apparatus 200 may configure a merge candidate list, which will be described later, and select one of the merge candidates included in the merge candidate list. . The selection of the merge candidate may be performed based on a merge index. Motion information of a current block may be derived from motion information of a selected merge candidate. Motion information of the selected merge candidate may be used as motion information of the current block.

As another example, when the (A)MVP mode is applied to the current block, the decoding apparatus 200 configures (A)MVP candidate list to be described later, and (A) an MVP candidate selected from among MVP candidates included in the MVP candidate list The motion vector of can be used as the MVP of the current block. The selection of the MVP may be performed based on the selection information (MVP flag or MVP index) described above. In this case, the decoding apparatus 200 may derive the MVD of the current block based on information about the MVD, and may derive a motion vector of the current block based on the MVP and MVD of the current block. Also, the decoding apparatus 200 may derive the reference picture index of the current block based on the reference picture index information. The picture indicated by the reference picture index in the reference picture list for the current block may be derived as a reference picture referenced for inter prediction of the current block.

Meanwhile, as described later, motion information of the current block may be derived without configuring a candidate list, and in this case, motion information of the current block may be derived according to a procedure disclosed in the prediction mode described below. In this case, the candidate list configuration as described above may be omitted.

The decoding apparatus 200 may generate prediction samples for the current block based on the motion information of the current block (S930). In this case, the decoding apparatus 200 may derive a reference picture based on the reference picture index of the current block, and derive predictive samples of the current block using samples of the reference block indicated by the motion vector of the current block on the reference picture. . In this case, as described later, a prediction sample filtering procedure for all or part of the prediction samples of the current block may be further performed depending on the case.

For example, the inter prediction unit 260 of the decoding apparatus 200 may include a prediction mode determination unit 261, a motion information derivation unit 262, and a prediction sample derivation unit 263, and the prediction mode determination unit The prediction mode for the current block is determined based on the prediction mode information received at (181), and the motion information (motion vector) of the current block is based on the motion information received from the motion information derivation unit 182. And/or a reference picture index), and predicted samples of the current block may be derived from the predicted sample deriving unit 183.

The decoding apparatus 200 generates residual samples for the current block based on the received residual information (S940). The decoding apparatus 200 may generate reconstructed samples for the current block based on the predicted samples and residual samples, and generate a reconstructed picture based on the reconstructed samples. (S950). As described above, an in-loop filtering procedure may be further applied to the reconstructed picture.

As described above, the inter prediction procedure may include a step of determining an inter prediction mode, a step of deriving motion information according to the determined prediction mode, and performing a prediction (generating a predictive sample) based on the derived motion information.

인터 예측 모드 결정(Determination of inter prediction mode)Determination of inter prediction mode

Various inter prediction modes may be used for prediction of a current block in a picture. For example, various modes such as merge mode, skip mode, MVP mode, and affine mode may be used. Decoder side motion vector refinement (DMVR) mode, adaptive motion vector resolution (AMVR) mode, and the like may be further used as ancillary modes. The affine mode may also be called aaffine motion prediction mode. The MVP mode may also be called AMVP (advanced motion vector prediction) mode.

Prediction mode information indicating the inter prediction mode of the current block may be signaled from the encoding device to the decoding device 200. The prediction mode information may be included in the bitstream and received by the decoding apparatus 200. The prediction mode information may include index information indicating one of a plurality of candidate modes. Alternatively, the inter prediction mode may be indicated through hierarchical signaling of flag information. In this case, the prediction mode information may include one or more flags. For example, the encoding apparatus 100 signals whether a skip mode is applied by signaling a skip flag, and indicates whether a merge mode is applied by signaling a merge flag when a skip mode is not applied, and when a merge mode is not applied. It may be indicated that the MVP mode is applied or may further signal a flag for additional classification. The affine mode may be signaled as an independent mode, or may be signaled as a mode dependent on a merge mode or an MVP mode. For example, the affine mode may be configured as one candidate of the merge candidate list or the MVP candidate list, as described later.

인터 예측 모드에 따른 움직임 정보의 도출(Derivation of motion information according to inter prediction mode)Derivation of motion information according to inter prediction mode

The encoding apparatus 100 or the decoding apparatus 200 may perform inter prediction using motion information of a current block. The encoding apparatus 100 may derive optimal motion information for the current block through a motion estimation procedure. For example, the encoding apparatus 100 may search for a similar reference block having a high correlation within a predetermined search range in a reference picture by a fractional pixel unit using the original block in the original picture for the current block, through which motion information Can be derived. The similarity of the block can be derived based on the difference of phase-based sample values. For example, the similarity of a block may be calculated based on a sum of absolute difference (SAD) between a current block (or a template of a current block) and a reference block (or a template of a reference block). In this case, motion information may be derived based on a reference block having the smallest SAD in the search area. The derived motion information may be signaled to the decoding apparatus according to various methods based on the inter prediction mode.

머지 모드 및 스킵 모드Merge mode and skip mode

When a merge mode is applied, motion information of a current prediction block is not directly transmitted, and motion information of a current prediction block is derived using motion information of a neighboring prediction block. Accordingly, the encoding apparatus 100 may indicate motion information of the current prediction block by transmitting flag information indicating that the merge mode is used and a merge index indicating which prediction blocks are used.

The encoding apparatus 100 must search a merge candidate block used to derive motion information of a current prediction block in order to perform a merge mode. For example, up to five merge candidate blocks may be used, but the present specification is not limited thereto. In addition, the maximum number of merge candidate blocks may be transmitted in the slice header, and the present specification is not limited thereto. After finding the merge candidate blocks, the encoding apparatus 100 may generate a merge candidate list, and may select a merge candidate block having the smallest cost as a final merge candidate block.

This specification provides various embodiments of a merge candidate block constituting a merge candidate list.

The merge candidate list may use 5 merge candidate blocks, for example. For example, four spatial merge candidates and one temporal merge candidate can be used.

Referring to FIG. 11, for prediction of a current block, a left neighboring block (A1), a bottom-left neighboring block (A2), a top-right neighboring block (B0), and an upper neighboring block (B1) ), at least one of a top-left neighboring block B2 may be used. The merge candidate list for the current block may be configured based on the procedure shown in FIG. 12.

The coding apparatus (encoding apparatus 100 or decoding apparatus 200) searches for spatial neighboring blocks of the current block and inserts the derived spatial merge candidates into the merge candidate list (S1210). For example, the spatial peripheral blocks may include blocks around the lower left corner of the current block, blocks around the left corner, blocks around the upper right corner, blocks around the upper corner, and blocks around the upper left corner. However, as an example, in addition to the spatial peripheral blocks described above, additional peripheral blocks such as a right peripheral block, a lower peripheral block, and a lower right peripheral block may be further used as the spatial peripheral blocks. The coding apparatus may detect available blocks by searching for spatial neighboring blocks based on priority, and derive motion information of the detected blocks as spatial merge candidates. For example, the encoding apparatus 100 or the decoding apparatus 200 searches the five blocks shown in FIG. 11 in the order of A1, B1, B0, A0, B2, sequentially indexes available candidates, and merges candidates It can be configured as a list.

The coding apparatus searches for temporal neighboring blocks of the current block and inserts the derived temporal merge candidate into the merge candidate list (S1220). The temporal peripheral block may be located on a reference picture that is a different picture from the current picture in which the current block is located. The reference picture in which the temporal neighboring block is located may be referred to as a collocated picture or a coll picture. The temporal neighboring blocks may be searched in the order of the lower right corner peripheral block and the lower right center block of the co-located block for the current block on the call picture. Meanwhile, when motion data compression is applied, specific motion information may be stored as representative motion information for each predetermined storage unit in a call picture. In this case, there is no need to store motion information for all blocks in the predetermined storage unit, thereby obtaining a motion data compression effect. In this case, the predetermined storage unit may be predetermined in units of 16x16 sample units, 8x8 sample units, or the like, or size information for a predetermined storage unit may be signaled from the encoding device 100 to the decoding device 200. have. When motion data compression is applied, motion information of a temporal peripheral block may be replaced with representative motion information of a certain storage unit in which the temporal peripheral block is located. That is, in this case, from an implementation point of view, an arithmetic right shift by a certain value based on the coordinates (top left sample position) of a temporal peripheral block, rather than a prediction block located at the coordinates of the temporal peripheral block, and then covers the position of the arithmetic left shift A temporal merge candidate may be derived based on the motion information of the prediction block. For example, if the constant storage unit is 2nx2n sample units, and the coordinates of the temporal peripheral block are (xTnb, yTnb), the corrected position ((xTnb >> n) << n), (yTnb >> n) The motion information of the prediction block located at << n)) can be used for temporal merge candidates. Specifically, for example, if the constant storage unit is 16x16 sample units, and the coordinates of the temporal peripheral block are (xTnb, yTnb), the corrected position ((xTnb >> 4) << 4), (yTnb >> 4) Motion information of the prediction block located at << 4)) can be used for temporal merge candidates. Or, for example, if the constant storage unit is 8x8 sample units, and the coordinates of the temporal peripheral block are (xTnb, yTnb), the corrected position ((xTnb >> 3) << 3), (yTnb >> 3 ) << 3)) motion information of the prediction block located at may be used for temporal merge candidate.

The coding apparatus may check whether the number of current merge candidates is smaller than the maximum number of merge candidates (S1230). The maximum number of merge candidates may be predefined or signaled from the encoding device 100 to the decoding device 200. For example, the encoding apparatus 100 may generate information on the number of maximum merge candidates, encode, and transmit the encoded information to the decoding apparatus 200 in the form of a bitstream. When the maximum number of merge candidates is filled, the subsequent candidate addition process may not proceed.

As a result of checking, if the number of current merge candidates is smaller than the number of maximum merge candidates, the coding apparatus inserts an additional merge candidate into the merge candidate list (S1240). Additional merge candidates are, for example, adaptive temporal motion vector prediction (ATMVP), combined bi-predictive merge candidates (if the slice type of the current slice is of type B) and/or zero vector merge. Candidates may be included.

When a motion vector prediction (MVP) mode is applied, a motion vector of a reconstructed spatial neighboring block (eg, the neighboring block of FIG. 11) and/or a motion vector corresponding to a temporal neighboring block (or Col block) is used. , A motion vector predictor (MVP) candidate list may be generated. That is, the motion vector of the reconstructed spatial neighboring block and/or the motion vector corresponding to the temporal neighboring block may be used as a motion vector predictor candidate. The prediction information may include selection information (eg, an MVP flag or an MVP index) indicating an optimal motion vector predictor candidate selected from among motion vector predictor candidates included in the list. At this time, the prediction unit may select a motion vector predictor of the current block from among motion vector predictor candidates included in the motion vector candidate list using the selection information. The prediction unit of the encoding apparatus 100 may obtain a motion vector difference (MVD) between a motion vector of a current block and a motion vector predictor, encode it, and output it in the form of a bitstream. That is, the MVD can be obtained by subtracting the motion vector predictor from the motion vector of the current block. At this time, the prediction unit of the decoding apparatus may obtain a motion vector difference included in the information about the prediction, and derive the motion vector of the current block through addition of the motion vector difference and the motion vector predictor. The prediction unit of the decoding apparatus may obtain or derive a reference picture index indicating the reference picture from the information on the prediction. For example, the motion vector predictor candidate list may be configured as shown in FIG. 13.

Referring to FIG. 13, the coding apparatus searches for a spatial candidate block for motion vector prediction and inserts it into a prediction candidate list (S1310). For example, the coding apparatus may search for neighboring blocks according to a predetermined search order, and add information of neighboring blocks satisfying the condition for the spatial candidate block to the prediction candidate list (MVP candidate list).

After constructing the spatial candidate block list, the coding apparatus compares the number of spatial candidate lists included in the prediction candidate list with a preset reference number (eg, 2) (S1320). If the number of spatial candidate lists included in the prediction candidate list is greater than or equal to the reference number (eg, 2), the coding apparatus may end the construction of the prediction candidate list.

However, if the number of spatial candidate lists included in the prediction candidate list is smaller than the reference number (eg, 2), the coding device searches for the temporal candidate block and inserts it into the prediction candidate list (S1330), and the temporal candidate block is used If it is not possible, the zero motion vector is added to the prediction candidate list (S1340).

예측 샘플 생성(Generation of prediction sample)Generation of prediction sample

The predicted block for the current block may be derived based on the motion information derived according to the prediction mode. The predicted block may include predictive samples (predictive sample array) of the current block. When the motion vector of the current block indicates a fractional sample unit, an interpolation procedure may be performed, and through this, prediction samples of the current block may be derived based on reference samples in a fractional sample unit in a reference picture. . When affine inter prediction is applied to a current block, prediction samples may be generated based on a motion vector per sample/subblock. When bi-direction prediction is applied, prediction samples derived based on first direction prediction (eg, L0 prediction) and prediction samples derived based on second direction prediction (eg, L1 prediction) ( The final prediction samples can be derived through weighted sum (per phase). As described above, reconstruction samples and reconstruction pictures may be generated based on the derived prediction samples, and then procedures such as in-loop filtering may be performed.

Hereinafter, an embodiment for performing inter prediction using a merge mode to which an MMVD technique according to an embodiment of the present disclosure is applied will be described.

In order to improve the accuracy of a motion vector in a merge mode or a skip mode, a refinement technique such as MVP may be applied. The merge with MVD (MMVD) technique can increase accuracy by adjusting the size and direction of a motion vector with respect to a selected candidate among candidates configured with a merge candidate list construction method.

The coding apparatus may determine a specific candidate from the merge candidate list as a base candidate. When the number of available base candidates is two, the first candidate and the second candidate in the list can be used as base candidates. The encoding apparatus 100 may transmit information on the selected base candidate by signaling a base candidate index. The number of base candidates may be variously set, and if the number of base candidates is 1, the base candidate index may not be used. Table 1 below shows an example of the base candidate index.

Referring to Table 1, if the base candidate index is 0, the motion vector corresponding to the first candidate is determined as the base candidate in the currently configured merge candidate list (or MVP candidate list), and if the base candidate index is 1, the currently configured merge candidate list ( Alternatively, a motion vector corresponding to the second candidate in the MVP candidate list) may be determined as a base candidate.

The encoding apparatus 100 may be refined by signaling the size (MMVD length) and direction (MMVD code) applied to the motion vector corresponding to the base candidate, where the length index (MMVD length index) is applied to the motion vector. The size of the applied MVD is indicated, and the direction index (MMVD code index) indicates the direction of the MVD applied to the motion vector. Table 2 below shows the size of the MVD (MMVD offset) according to the length index (MMVD length index), and Table 3 shows the direction of the MVD according to the direction index (MMVD code index).

When considering a base candidate, a distance index, and a direction index, a motion search method in MMVD may be expressed as shown in FIG. 14. In particular, in the case of bidirectional prediction, a motion vector in the L1 direction may be derived using a mirroring scheme for the L0 motion vector.

Referring to FIG. 14, when an MMVD offset such as +s and +2s is applied to a motion vector for an L0 reference picture, mirroring is performed for an L1 reference picture temporally opposite from the L0 reference picture based on the current picture. This can be applied.

According to the signaling method used in MMVD, when considering 2 base candidates, 8 MMVD length indexes, and 4 MMVD code indexes, there are a total of 64 MVD candidates for motion vector improvement. This increases the complexity of the encoder as well as it is difficult to see that the size and direction of the motion vector are efficiently considered, so the embodiments herein provide a method and apparatus for efficiently applying the MMVD technique.

In order to effectively signal MVD in AMVP mode, adaptive motion vector resolution (AMVR) technology has been applied. When the size of the motion vector is large, many bits are required for signaling of the motion vector, so a 1-integer pixel or 4-integer pixel is used to reduce the bits required for transmission. An operation of down-scaling the MVD having 1/4 or 1/16 may be performed. If the AMVR index (imv_idx) is 0, the encoding device 100 signals MVD without application of AMVR, and if imv_idx is 1, the MVD of 1-integer pixels is scaled by 1/4 and signaled, and if imv_idex is 2, 4-integer The MVD of the pixel may be signaled by being scaled by 1/16.

Since AMVR technology becomes an index reflecting the characteristics of motion of each image or block, especially the size of motion, the embodiment of the present specification allows the distance table to be adaptively selected in the MMVD using the imv_idx value. We propose a method that can reduce index overhead and improve compression performance.

15 shows an example of a flowchart for performing prediction using a merge mode to which a merge with motion vector difference (MMVD) technique according to an embodiment of the present disclosure is applied. The operations illustrated in FIG. 15 may be performed by the decoding apparatus 200 or the video signal processing apparatus 500.

In operation S1510, the decoding apparatus 200 obtains a motion vector for inter-frame prediction of the current block from at least one neighboring block adjacent to the current block based on the merge index. Before the step S1510, the decoding apparatus 200 confirms that the merge mode is applied to the current block from the bitstream transmitted from the encoding apparatus 100, and parses the merge index, thereby candidates used for prediction of the current block among the current merge candidates. (Motion vector) can be determined.

In operation S1520, the decoding apparatus 200 may determine the MMVD offset applied to the motion vector based on the AMVR index (imv_idx or imv_idc) and the MMVD length index (Distance IDX or mmvd_distance_idx). Here, the AMVR index is associated with one of the predetermined MMVD candidate sets (eg, Cases 1 to 3 in Table 4D) based on the resolution of the MMVD offset values, and the MMVD length index moves in the MMVD candidate set associated with the AMVR index. The MMVD offset value to be applied to the vector can be indicated.

In operation S1530, the decoding apparatus 200 may generate a prediction sample of the current block based on the motion vector to which the MMVD offset is applied and the reference picture associated with the merge index. That is, the decoding apparatus 200 determines the final motion vector by adding the MMVD offset determined in step S1520 to the motion vector derived from the merge index in step S1510, and the current block from the sample indicated by the final motion vector in the reference picture. Can generate predictive samples.

According to an embodiment of the present specification, as shown in Table 4 below, since the MMVD length index indicates an MVMD offset value within a range defined by the AMVR index (for example, 4), all ranges are based only on the MMVD length index as shown in Table 2. In comparison with indicating the MMVD offset value, the bit amount required to transmit the MMVD length index can be reduced.

In one embodiment, the decoding apparatus 200 obtains an MMVD direction index (eg, Direction IDX or MMVD_direction_idx in Table 2) indicating the sign of the MMVD offset, applies a sign corresponding to the MMVD direction index to the MMVD offset, A predicted sample may be generated by adding a signed MMVD offset corresponding to a MMVD direction index to a motion vector and using a final motion vector to which a signed MMVD offset is added. By using the MMVD direction index, accuracy according to refinement of a motion vector can be increased.

Table 4 shows a table of MMVD offset values for the MMVD length index according to this embodiment. According to Table 4, different MMVD offsets are allocated for each MMVD length index according to imv_idx. That is, in case 1, imv_idx is 0, the base motion vector may be adjusted by a distance of 1/4-pel to 2-pel. In addition, in case 2, when imv_idx is 1, the base motion vector may be adjusted by a distance of 1/2-pel to 4-pel. Finally, in case 3, imv_idx is 2, and the base motion vector may be adjusted by a distance of 1-pel to 8-pel. The number of candidates and candidate values in the distance table described in this specification are only examples, and other numbers or different values may be used.

In one embodiment, the AMVR index may be determined based on the resolution of a motion vector difference (MVD) applied to a motion vector of a neighboring block associated with the merge index. For example, the AMVR index may be determined based on AMVR information (AMVR index) of spatial or temporal neighboring blocks used in the process of generating a merge or MVP candidate list of the current block.

AMVR mode is applied in AMVP and is not used in merge/skip mode. Therefore, in order to determine the above-mentioned AMVR mode-based length table determination method, the AMVR index can be separately set in the merge/skip mode. That is, when the current block is in the merge/skip mode, the AMVR index (imv_idx) of the neighboring block is set and stored so that the AMVR can be applied when constructing candidates for the MMVD. At this time, since the coding device performs context modeling using imv_idx of the left or upper neighboring block in the parsing process, MMVD in order to prevent imv_idx of the stored neighboring block from being applied to the parsing process in the decoding process of the block to which merge/skip mode is applied. The AMVR index of the block to which the is applied is distinguished from the AVMR index of the block to which the AMVP is applied by naming it as a separate syntax element (eg, imv_idc).

The following embodiment provides a method of storing an AMVR index (imv_idc) in the process of constructing an MVP candidate list for a block to which merge/skip mode is applied. This is because according to MMVD, a base motion vector corresponding to a selected candidate among MVP candidates configured in a decoding process of a block to which merge/skip mode is applied is adjusted. In the process of constructing the candidate list, the AMVR index may be set as follows according to the characteristics of the adjacent block (resolution of the MVD or AMVR index).

-For spatially adjacent blocks, the AMVR index of the adjacent blocks is used.

-For temporally adjacent blocks, a default value (eg 0) is used.

-For a neighbor block to which HMVP is applied, an AMVR index matching candidates stored in the HMVP buffer is used, or a default value (for example, 0) is always used for an HMVP candidate.

-For pairwise candidates, when the candidates of the L0 motion vector (L0 block) and the L1 motion vector (L1 block) have the same AMVR index, a common AMVR index is used, and the L0 motion vector (L0 block) and L1 If the motion vector (L1 block) has a different AMVR index, the default value is used.

-When the candidates of the L0 motion vector (L0 block) and the L1 motion vector (L1 block) have the same AMVR index, the corresponding AMVR index is used, and in other cases, the larger AMVR index value is used.

-In the case of a zero vector, the default value (eg 0) is used.

It is natural that all of the above-described methods may be applied or only a part may be applied.

In addition, when constructing a triangular mode candidate list, the AMVR index value of adjacent blocks can be stored to propagate the merge/skip mode afterwards. At this time, in the triangular mode, as shown in FIG. 16, one CU (coding unit) is divided into two triangular shaped prediction units (PUs), and each PU can be predicted by uni-prediction. For each PU, a candidate list for unidirectional prediction may be constructed in a manner similar to a general merge/skip mode. When a triangular mode is applied, one CU is composed of two PUs (Cand0, Cand1), so the AMVR index of the corresponding block (CU) can be determined by considering all of the AMVR indexes of the two blocks (PU). Can.

-Use AMVR index of Cand0.

-Use Cand1's AMVR index.

-When Cand0 and Cand1 have the same AMVR index, the corresponding value is used.

-If the AMVR index of Cand0 and Cand1 are different, the default value is used.

-If the AMVR index of Cand0 and Cand1 are different, a larger value is used.

It is natural that all or some of the above-described methods may be applied.

In addition, when constructing a candidate list in a multi-hypothesis (M/H) mode, the AMVR index of adjacent blocks can be stored so that the AMVR index value is propagated to the merge/skip mode later. At this time, the M/H mode is a technique in which intra prediction and inter prediction are combined in the merge/skip mode, and signals both indexes for the intra mode and the merge mode. The candidate list is constructed in a similar manner to the normal merge/skip mode, and when the M/H mode is applied, the AMVR index can be set for the corresponding block as follows.

-When the block is spatially adjacent, the AMVR index of the adjacent block is used.

-When the block is temporally adjacent, the default value (eg 0) is used.

-For HMVP candidates, i) use the AMVR index matching the candidates stored in the HMVP buffer, or ii) always use the default value (eg 0).

-When pairwise, i) L0 candidate (L0 block) and L1 candidate (L1 block) use the common AMVR index when they have the same AMVR index; otherwise, use the default value (eg 0) Or, ii) When the L0 candidate (L0 block) and the L1 candidate (L1 block) have the same AMVR index, a common AMVR index is used, and in other cases, a larger AMVR index is used.

-For zero vectors, use default values (eg 0).

It is natural that the above-described methods may be applied or some may be applied.

According to an embodiment of the present invention, the AMVR index may be updated based on the MMVD length (offset). Also, the updated AMVR index may be reused as the AMVR index of at least one block processed after the current block. Using the above method, the AMVR index of the base motion vector for MMVD can be derived, and the distance of the motion vector for refinement can be determined by selecting the MMVD length table based on the derived AMVR index. However, even if the MMVD length table is selected based on the AMVR index of the base motion vector, a distance value such as 1-pel or 4-pel can be selected among the candidates in the table, so the AMVR index is selected based on the length selected in the MMVD process. Can be updated. This is because MMVD length also plays the role of AMVR. Accordingly, the AMVR index can be updated according to the selected MMVD length as shown in Table 5 below.

That is, if the MMVD length is determined to be 4-pel or 8-pel, it is similar to the AMVR index (imv_idc) 2, so even if the AMVR index of the base motion vector is 0, it can be updated to 2. In addition, if the MMVD distance is determined to be 1-pel or more, it can be updated to 1 because it is similar to the AMVR index (imv_idc) 1.

That is, if the MMVD offset is greater than or equal to the reference value, the AMVR index is determined to indicate the first MMVD set, and if the size of the MMVD offset is less than the reference value, the MMVD range index is determined to indicate the second MMVD set index. The first MMVD set has a value greater than the MMVD offset of the second MMVD set for the same MMVD length index.

The magnitude of the x and y values of the base motion vector of the MMVD may have an effect similar to that of the AMVR of the block in deriving the distance for refinement. In addition, even if the AMVR index is not applied, there is an advantage that it is not dependent on other tools. Accordingly, the present embodiment provides a method of determining the MMVD length table according to the value of the base motion vector. Table 6 below is another example of a table showing the relationship between the MMVD length index and the MMVD offset values, and shows a method of determining the MMVD length table according to the value of the base motion vector.

Case 1 has the following conditions.

-When bi-directional prediction is applied and 4-pel unit motion vector is used

(L0_x% 16 == 0 && L0_y% 16 == 0 && L1_x% 16 == 0 && L1_y% 16 == 0)

-When unidirectional prediction is applied and 4-pel unit motion vector is used

(LX_x% 16 == 0 && LX_y% 16 == 0, X = 0, 1)

If the condition of Case 1 is satisfied, it is adjusted to a distance of 1-pel to 8-pel.

If Case 1 is not satisfied, the conditions for Case 2 are as follows.

-When bi-directional prediction is applied and 1-pel unit motion vector is used

(L0_x% 4 == 0 && L0_y% 4 == 0 && L1_x% 4 == 0 && L1_y% 4 == 0)

-When unidirectional prediction is applied and a motion vector of 1-pel comfort is used

(LX_x% 4 == 0 && LX_y% 4 == 0, X = 0, 1)

If the condition of Case 2 is satisfied, it is adjusted to a distance of 1/2-pel to 4-pel.

When Case 1 and Case 2 are not satisfied, the distance may be adjusted to a distance of 1/4-pel to 2-pel corresponding to Case 3. The number of candidates and candidate values in the distance table described in this specification are only examples, and it is natural that other numbers or different values may be applied.

Case 1 to Case 3 described above may be modified and applied as follows. That is, even if one of the candidates to which bi-directional prediction is applied has a motion vector in units of 4-pel or 1-pel as shown in the following conditions, it may be determined that the condition is satisfied.

For example, the condition of Case 1 may be as follows.

-When bi-directional prediction is applied and 4-pel unit motion vector is used

((L0_x% 16 == 0 && L0_y% 16 == 0)||(L1_x% 16 == 0 && L1_y% 16 == 0))

-When unidirectional prediction is applied and 4-pel unit motion vector is used

(LX_x% 16 == 0 && LX_y% 16 == 0, X = 0, 1)

If Case 1 is not satisfied, the conditions for Case 2 are as follows.

-When bi-directional prediction is applied and 1-pel unit motion vector is used

(((L0_x% 4 == 0 && L0_y% 4 == 0)||(L1_x% 4 == 0 && L1_y% 4 == 0))

(LX_x% 4 == 0 && LX_y% 4 == 0, X = 0, 1)

This embodiment may be applied when AMVR is not used, or may be used regardless of whether AMVR is applied. In addition, when the AMVR is applied (imv_dic = 1, 2), the MMVD length table is determined according to the AMVR index, and when the AMVR is not applied (imv_idc = 0), the MMVD is based on the pixel unit of the motion vector as in this embodiment. The length table can be determined.

That is, the range of the MMVD offset applied to the motion vector may be determined based on the resolution of the position coordinates indicated by the AMVR index and the base motion vector. For example, when the AMVR index is 0, the range of the MMVD offset applied to the motion vector for prediction of the current block may be determined based on the position coordinates indicated by the motion vector. Here, the position coordinates may include a horizontal position (x coordinate) and/or a vertical position (y coordinate) from an arbitrary position in the picture or block (eg, the position of the upper left pixel).

According to an embodiment of the present specification, the size of the current block may be considered in the process of applying the MMVD by reflecting the characteristics of the current block. The table for the MMVD offset value may be determined in consideration of at least one of the size of the x, y values of the AMVR mode, the base motion vector, or the size of the current block.

That is, the range of the MMVD offset applied to the motion vector may be determined based on the AMVR index and the size of the current block. For example, the following method may be considered.

-When the AMVR index (imv_idc) is 0 and wxh> 256 (hereinafter, w corresponds to the width of the current block, h corresponds to the height of the current block), the MMVD length table of {2, 4, 8, 16} is used, and Table 4 or Table 6 is used otherwise.

-When AMVR index is 0 and w> 16 && h> 16, the MMVD length table of {2, 4, 8, 16} is used, otherwise Table 4 or Table 6 is used.

-When AMVR index is greater than 0 and w x h> 256, the MMVD length table of {2, 4, 8, 16} is used, otherwise Table 4 or Table 6 is used.

-When the AMVR index is greater than 0 and w> 16 && h> 16, the MMVD length table of {2, 4, 8, 16} is used, otherwise Table 4 or Table 6 is used.

Here, the threshold value compared with the used block size may be changed, and the width and height may be considered simultaneously, or the width x height may be considered. It is also natural that the AMVR index and/or base motion vector can be considered together.

The MMVD method may be implemented by the video signal processing apparatus 500 of FIG. 5 using the MMVD index within the MMVD offset range determined in consideration of the above-described AMVR index.

For example, the video signal processing apparatus 500 may include a memory 520 for storing a video signal, and a processor 510 for processing a video signal while being combined with the memory. The processor 510 obtains a motion vector for inter-frame prediction of the current block from at least one neighboring block adjacent to the current block based on the merge index, and applies the motion vector to the motion vector based on the AMVR index and the MMVD length index. The MMVD offset is determined, and a prediction sample of the current block is set based on a motion vector to which the MMVD offset is applied and a reference picture associated with the merge index, wherein the AMVR index is a predetermined MMVD based on the resolution of the MMVD offset values. Associated with one of the candidate sets, the MMVD length index may indicate an MMVD offset value to be applied to the motion vector in the MMVD candidate set associated with the AMVR index.

In one embodiment, the processor 510 obtains an MMVD direction index indicating the sign of the MMVD offset, applies a sign corresponding to the MMVD direction index to the MMVD offset, and sets the applied MMVD offset to the motion vector Can be.

In one embodiment, the AMVR index may be determined based on the resolution of the MVD applied to the motion vector of the neighboring block associated with the merge index.

In one embodiment, the AMVR index may be updated based on the size of the MMVD offset indicated by the MMVD length index, and the updated AMVR index may be reused as the AMVR index of the block processed after the current block. For example, if the MMVD offset is greater than or equal to the reference value, the AMVR index is determined to indicate the first MMVD set, and if the size of the MMVD offset is less than the reference value, the AMVR index indicates the second MMVD set index. It is determined, and the first MMVD set may have a value greater than the MMVD offset of the second MMVD set for the same MMVD length index.

In one embodiment, a range of the MMVD offset applied to the motion vector may be determined based on the AMVR index and the pixel unit of the motion vector.

In one embodiment, the range of the MMVD offset applied to the motion vector may be determined based on the AMVR index and the size of the current block.

Based on the above-described embodiment of the present invention, the encoded information (ex. encoded video/video information) derived by the encoding device may be output in the form of a bitstream. The encoded information may be transmitted or stored in units of network abstraction layer (NAL) units in the form of a bitstream. The bitstream may be transmitted over a network or may be stored in a (non-transitory) digital storage medium. Also, as described above, the bitstream is not directly transmitted from the encoding device to the decoding device, and may be streamed/downloaded through an external server (ex. content streaming server). Here, the network may include a broadcasting network and/or a communication network, and the digital storage medium may include various storage media such as USB, SD, CD, DVD, Blu-ray, HDD, SSD.

Embodiments described in the present invention may be implemented and implemented on a processor, microprocessor, controller, or chip. For example, the functional units shown in each figure may be implemented and implemented on a computer, processor, microprocessor, controller, or chip.

The processing method to which the present invention is applied may be produced in the form of a program executed by a computer, and may be stored in a computer readable recording medium. Multimedia data having a data structure according to the present invention can also be stored in a computer-readable recording medium. The computer-readable recording medium includes all kinds of storage devices and distributed storage devices in which computer-readable data is stored. The computer-readable recording medium includes, for example, Blu-ray Disc (BD), Universal Serial Bus (USB), ROM, PROM, EPROM, EEPROM, RAM, CD-ROM, magnetic tape, floppy disk and optical. It may include a data storage device. In addition, the computer-readable recording medium includes media implemented in the form of a carrier wave (for example, transmission via the Internet). In addition, the bitstream generated by the encoding method may be stored in a computer-readable recording medium or transmitted through a wired or wireless communication network.

Further, an embodiment of the present invention may be implemented as a computer program product by program code, and the program code may be executed on a computer by an embodiment of the present invention. The program code can be stored on a computer readable carrier.

That is, the embodiments herein can be implemented by a non-transitory computer-executable component that stores computer-executable components configured to execute on one or more processors of a computing device. The computer-executable component according to an embodiment of the present disclosure obtains a motion vector for inter-frame prediction of the current block from at least one neighboring block adjacent to the current block based on the merge index, and based on the AMVR index and the MMVD length index. It is set to determine an MMVD offset applied to a motion vector, and to generate a prediction sample of the current block based on a motion vector to which the MMVD offset is applied and a reference picture associated with the merge index. Here, the AMVR index is associated with one of the predetermined MMVD candidate sets based on the resolution of the MMVD offset values, and the MMVD length index indicates an MMVD offset value to be applied to the motion vector among candidate offset values associated with the AMVR index. can do. In addition, computer-executable components for implementing the various embodiments described herein can be stored on a non-transitory computer-readable medium.

The decoding apparatus 200 and the encoding apparatus 100 to which the present invention is applied may be included in a digital device. The term "digital device" includes, for example, all digital devices capable of performing at least one of transmission, reception, processing, and output of data, content, and services. Here, the processing of the data, content, service, etc. by the digital device includes an operation of encoding and/or decoding data, content, service, and the like. These digital devices are paired or connected (hereinafter referred to as'pairing') with other digital devices, external servers, etc. through a wire/wireless network to transmit and receive data. Convert it accordingly.

Digital devices include, for example, fixed devices such as network TV, network broadcast broadband TV (HBBTV), smart TV, Internet protocol television (IPTV), personal computer (PC), and the like. , PDA (personal digital assistant), a smart phone (smart phone), a tablet PC (tablet PC), a mobile device (mobile device or handheld device) such as a laptop.

Meanwhile, the term "wired/wireless network" described herein refers to a communication network that supports various communication standards or protocols for interconnection and/or data transmission and reception between digital devices or digital devices and external servers. . Such a wired/wireless network may include both a communication network to be supported in the current or future by a standard and a communication protocol therefor, for example, Universal Serial Bus (USB), Composite Video Banking Sync (CVBS), component, S-Video (Analog), communication standards or protocols for wired connections such as digital visual interface (DVI), high definition multimedia interface (HDMI), RGB, D-SUB, Bluetooth, radio frequency identification (RFID), infrared communication (IrDA, infrared data association), UWB (ultra wideband), ZigBee, digital living network alliance (DLNA), wireless LAN (WLAN) (Wi-Fi), wireless broadband (Wibro), world interoperability for microwave access, high speed downlink packet access (HSDPA), long term evolution (LTE), and Wi-Fi direct.

Hereinafter, in the case of merely referring to a digital device in the present specification, it may mean a fixed device or a mobile device or both.

Meanwhile, the digital device is an intelligent device that supports, for example, a broadcast reception function, a computer function or support, and at least one external input, e-mail, web browsing through a wired/wireless network described above ( It can support web browsing, banking, games, and applications. In addition, the digital device may include an interface for supporting at least one input or control means (hereinafter referred to as an input means), such as a handwritten input device, a touch screen, and a spatial remote control. The digital device can use a standardized general-purpose operating system (OS). For example, a digital device can add, delete, modify, and update various applications on a general-purpose OS kernel, through which further You can configure and provide a user-friendly environment.

The embodiments described above are those in which the components and features of the present specification are combined in a predetermined form. Each component or feature should be considered optional unless stated otherwise. Each component or feature may be implemented in a form that is not combined with other components or features. In addition, it is also possible to constitute an embodiment of the present specification by combining some components and/or features. The order of the operations described in the embodiments herein can be changed. Some configurations or features of one embodiment may be included in other embodiments, or may be replaced with corresponding configurations or features of other embodiments. It is obvious that the claims may not be explicitly cited in the claims, and the embodiments may be combined or included as new claims by amendment after filing.

In the case of implementation by firmware or software, an embodiment of the present specification may be implemented in the form of a module, procedure, function, etc. that performs the functions or operations described above. The software code can be stored in memory and driven by a processor. The memory is located inside or outside the processor, and can exchange data with the processor by various known means.

It will be apparent to those skilled in the art that the present specification may be embodied in other specific forms without departing from essential features of the present specification. Therefore, the above detailed description should not be construed as limiting in all respects, but should be considered illustrative. The scope of the present specification should be determined by rational interpretation of the appended claims, and all changes within the equivalent scope of the present specification are included in the scope of the present specification.

The preferred embodiments of the present invention described above are disclosed for the purpose of illustration, and those skilled in the art improve and change various other embodiments within the technical spirit and the technical scope of the present invention disclosed in the appended claims. , Replacement or addition may be possible.

Claims

A method for processing a video signal using inter prediction,

Obtaining a motion vector for inter-frame prediction of the current block from at least one neighboring block adjacent to the current block based on a merge index;

Determining an MMVD offset applied to the motion vector based on an adaptive motion vector resolution (AMVR) index and a merge with motion vector difference (MMVD) distance index; And

Generating a prediction sample of the current block based on a motion vector to which the MMVD offset is applied and a reference picture associated with the merge index,

The AMVR index is associated with one of the predetermined MMVD candidate sets based on the resolution of the MMVD offset values,

And the MMVD length index indicates an MMVD offset value to be applied to the motion vector in a set of MMVD candidates associated with the AMVR index.
According to claim 1,

Generating a prediction sample of the current block,

Obtaining an MMVD direction index indicating the sign of the MMVD offset;

Applying a sign corresponding to the MMVD direction index to the MMVD offset; And

And adding the MMVD offset to which the sign is applied to the motion vector.
According to claim 1,

The AMVR index,

And determining based on a resolution of a motion vector difference (MVD) applied to a motion vector of a neighboring block related to the merge index.
According to claim 1,

The AMVR index,

Updated based on the size of the MMVD offset indicated by the MMVD length index,

The updated AMVR index is reused as an AMVR index of a block processed after the current block.
According to claim 4,

If the MMVD offset is greater than or equal to a reference value, the AMVR index is determined to indicate the first set of MMVDs,

If the size of the MMVD offset is smaller than a reference value, the AMVR index is determined to indicate the second MMVD set index,

The method of claim 1, wherein the first MMVD set has a value greater than an MMVD offset of the second MMVD set for the same MMVD length index.
According to claim 1,

And a range of the MMVD offset applied to the motion vector is determined based on the resolution of the AMVR index and the position coordinate indicated by the motion vector.
According to claim 1,

A method for determining the range of the MMVD offset applied to the motion vector based on the AMVR index and the size of the current block.
An apparatus for processing a video signal using inter prediction,

A memory for storing the video signal; And

A processor coupled with the memory,

The processor,

A motion vector for inter-frame prediction of the current block is obtained from at least one neighboring block adjacent to the current block based on the merge index,

Based on an adaptive motion vector resolution (AMVR) index and a merge with motion vector difference (MMVD) distance index, an MMVD offset applied to the motion vector is determined,

It is set to generate a prediction sample of the current block based on a motion vector to which the MMVD offset is applied and a reference picture associated with the merge index,

The AMVR index is associated with one of the predetermined MMVD candidate sets based on the resolution of the MMVD offset values,

And the MMVD length index indicates an MMVD offset value to be applied to the motion vector in a set of MMVD candidates associated with the AMVR index.
The method of claim 8,

The processor,

Obtain an MMVD direction index indicating the sign of the MMVD offset,

A code corresponding to the MMVD direction index is applied to the MMVD offset,

And the MMVD offset to which the sign is applied is set to be added to the motion vector.
The method of claim 8,

The AMVR index,

And determining based on a resolution of a motion vector difference (MVD) applied to a motion vector of a neighboring block related to the merge index.
The method of claim 8,

The AMVR index,

Updated based on the size of the MMVD offset indicated by the MMVD length index,

And the updated AMVR index is reused as an AMVR index of a block processed after the current block.
The method of claim 11,

If the MMVD offset is greater than or equal to a reference value, the AMVR index is determined to indicate the first set of MMVDs,

If the size of the MMVD offset is smaller than a reference value, the AMVR index is determined to indicate the second MMVD set index,

And wherein the first MMVD set has a value greater than the MMVD offset of the second MMVD set for the same MMVD length index.
The method of claim 8,

And a range of an MMVD offset applied to the motion vector is determined based on the resolution of the AMVR index and the position coordinate indicated by the motion vector.
The method of claim 8,

And an MMVD offset range applied to the motion vector is determined based on the AMVR index and the size of the current block.
A non-transitory computer-executable component storing computer executable components configured to execute on one or more processors of a computing device, the computer executable components comprising:

A motion vector for inter-frame prediction of the current block is obtained from at least one neighboring block adjacent to the current block based on the merge index,

Based on the adaptive motion vector resolution (AMVR) index and the merge motion vector difference (MMVD) distance index, an MMVD offset applied to the motion vector is determined,

It is set to generate a prediction sample of the current block based on a motion vector to which the MMVD offset is applied and a reference picture associated with the merge index,

The AMVR index is associated with one of the predetermined MMVD candidate sets based on the resolution of the MMVD offset values,

The MMVD length index indicates an MMVD offset value to be applied to the motion vector in a set of MMVD candidates associated with the AMVR index.