KR20230105660A - Method and apparatus for video encoding and decoding improving merge mode - Google Patents

Abstract

A video encoding/decoding method and device are provided. The video decoding method according to the present disclosure may include the steps of: determining a first mode based on at least one of a combined inter intra prediction (CIIP) mode, a geometric segmentation mode, and a merge mode using motion vector difference; and determining a motion vector from a merge candidate list; and generating a prediction block of a current block based on the first mode and the motion vector.

Description

Video encoding/decoding method and apparatus for improving merge mode

The present invention relates to a video encoding/decoding method and apparatus for improving merge mode. More specifically, it relates to a video encoding/decoding method and apparatus for generating a prediction block of a current block by adding a new type of merge mode to a normal merge mode.

The contents described below merely provide background information related to the present embodiment and do not constitute prior art.

Since video data has a large amount of data compared to audio data or still image data, it requires a lot of hardware resources including memory to store or transmit itself without processing for compression.

Therefore, when video data is stored or transmitted, an encoder is used to compress and store or transmit the video data, and a decoder receives, decompresses, and reproduces the compressed video data. Examples of such video compression technologies include H.264/AVC, High Efficiency Video Coding (HEVC), and Versatile Video Coding (VVC), which has improved coding efficiency by about 30% or more compared to HEVC.

However, since the size, resolution, and frame rate of video are gradually increasing, and the amount of data to be encoded accordingly increases, a new compression technology with higher encoding efficiency and higher picture quality improvement effect than existing compression technologies is required.

Combined Inter/Intra Prediction (CIIP) mode is a method of generating a prediction block of a current block by performing a weighted average of an intra prediction signal and an inter prediction signal. The geometric partitioning mode divides one Coding Unit (CU) into two regions and performs inter prediction independently on the divided two regions to obtain a weighted average of the two inter prediction signals generated to obtain a prediction block of the current block. how to create The merge mode using the motion vector difference corrects the motion vector by adding the motion vector difference to the motion vector derived by the general merge mode. It is necessary to increase the accuracy of merge mode and increase coding efficiency by combining CIIP mode, geometric segmentation mode, or merge mode using motion vector difference.

An object of the present disclosure is to provide a method and apparatus for generating a prediction block of a current block based on a combined inter/intra prediction (CIIP) mode and a geometric segmentation mode.

In addition, an object of the present disclosure is to provide a method and apparatus for generating a prediction block of a current block based on a CIIP mode and a merge mode using a motion vector difference.

In addition, an object of the present disclosure is to provide a method and apparatus for generating a prediction block of a current block based on a geometric division mode and a merge mode using a motion vector difference.

In addition, an object of the present disclosure is to provide a method and apparatus for generating a prediction block of a current block based on CIIP mode, geometric partitioning mode, and merge mode using motion vector difference.

In addition, an object of the present disclosure is to provide a method and apparatus for improving video encoding/decoding efficiency.

In addition, an object of the present disclosure is to provide a recording medium storing a bitstream generated by a video encoding/decoding method or apparatus of the present disclosure.

In addition, an object of the present disclosure is to provide a method and apparatus for transmitting a bitstream generated by the video encoding/decoding method or apparatus of the present disclosure.

A video decoding method according to the present disclosure includes determining a first mode based on at least one of a Combined Inter Intra Prediction (CIIP) mode, a geometric segmentation mode, and a merge mode using a motion vector difference; motion in a merge candidate list. The method may include determining a vector and generating a prediction block of a current block based on the first mode and the motion vector.

A video encoding method according to the present disclosure includes determining a first mode based on at least one of a CIIP mode, a geometric partitioning mode, and a merge mode using motion vector difference; determining a motion vector from a merge candidate list; and and generating a prediction block of the current block based on the first mode and the motion vector.

Also, according to the present disclosure, a method of transmitting a bitstream generated by a video encoding method or apparatus according to the present disclosure may be provided.

Also, according to the present disclosure, a recording medium storing a bitstream generated by a video encoding method or apparatus according to the present disclosure may be provided.

In addition, according to the present disclosure, a recording medium storing a bitstream used for image restoration after being received and decoded by the video decoding apparatus according to the present disclosure may be provided.

A method and apparatus for generating a prediction block of a current block based on a Combined Inter/Intra Prediction (CIIP) mode and a geometric segmentation mode combined with the present disclosure may be provided.

Also, according to the present disclosure, a method and apparatus for generating a prediction block of a current block based on a CIIP mode and a merge mode using a motion vector difference may be provided.

In addition, according to the present disclosure, a method and apparatus for generating a prediction block of a current block based on a geometric division mode and a merge mode using a motion vector difference may be provided.

Also, according to the present disclosure, a method and apparatus for generating a prediction block of a current block based on CIIP mode, geometric partitioning mode, and merge mode using motion vector difference may be provided.

Also, according to the present disclosure, a method and apparatus for improving video encoding/decoding efficiency may be provided.

Effects obtainable in the present disclosure are not limited to the effects mentioned above, and other effects not mentioned may be clearly understood by those skilled in the art from the description below. will be.

1 is an exemplary block diagram of an image encoding apparatus capable of implementing the techniques of this disclosure.
2 is a diagram for explaining a method of dividing a block using a QTBTTT structure.
3A and 3B are diagrams illustrating a plurality of intra prediction modes including wide-angle intra prediction modes.
4 is an exemplary diagram of neighboring blocks of a current block.
5 is an exemplary block diagram of a video decoding apparatus capable of implementing the techniques of this disclosure.
6 is a diagram for explaining a method of generating a prediction block of a current block in a combined inter/intra prediction (CIIP) mode.
7 is a diagram for describing neighboring blocks referred to for determining weight values in a combined intra-picture inter-prediction mode according to an embodiment of the present disclosure.
8 is a diagram for explaining a method of determining a weight value in a combined intra-screen inter-prediction mode according to an embodiment of the present disclosure.
9 is a diagram for explaining a method of applying a geometric division mode to a 32x32 block according to an embodiment of the present disclosure.
10A and 10B are diagrams for explaining an angle parameter and a distance parameter in a geometric segmentation mode according to an embodiment of the present disclosure.
11 is a diagram for explaining a lookup table of segmentation direction information in a geometric segmentation mode according to an embodiment of the present disclosure.
12 is a diagram for explaining direction information of a motion vector difference according to an embodiment of the present disclosure.
13 is a diagram for explaining distance information of a motion vector difference according to an embodiment of the present disclosure.
14 is a diagram for explaining a flowchart of applying inter prediction according to an embodiment of the present disclosure.
15 is a diagram for explaining a flowchart of applying a new mode in inter prediction according to an embodiment of the present disclosure.
16 is a diagram for explaining a flowchart for applying a new mode in inter prediction according to another embodiment of the present disclosure.
17 is a diagram for explaining a flowchart of applying a new mode in inter prediction according to another embodiment of the present disclosure.
18 is a diagram for explaining a new mode combining a geometric partitioning mode and a CIIP mode according to an embodiment of the present disclosure.
19 is a diagram for explaining a new mode combining a CIIP mode and a merge mode using motion vector difference according to an embodiment of the present disclosure.
20 is a diagram for explaining a new mode in which a geometric division mode and a merge mode using motion vector difference are combined according to an embodiment of the present disclosure.
21 is a diagram for explaining a new mode combining a geometric division mode, a CIIP mode, and a merge mode using a motion vector difference according to an embodiment of the present disclosure.
22 is a diagram for explaining a video decoding process according to an embodiment of the present disclosure.
23 is a diagram for explaining a video encoding process according to an embodiment of the present disclosure.

DETAILED DESCRIPTION Some embodiments of the present disclosure are described in detail below with reference to exemplary drawings. In adding reference numerals to components of each drawing, it should be noted that the same components have the same numerals as much as possible even if they are displayed on different drawings. In addition, in describing the present embodiments, if it is determined that a detailed description of a related known configuration or function may obscure the gist of the present embodiments, the detailed description will be omitted. In the present disclosure, image and video may be used interchangeably.

1 is an exemplary block diagram of an image encoding apparatus capable of implementing the techniques of this disclosure. Hereinafter, with reference to the illustration of FIG. 1, an image encoding device and sub-components of the device will be described.

The image encoding apparatus includes a picture division unit 110, a prediction unit 120, a subtractor 130, a transform unit 140, a quantization unit 145, a rearrangement unit 150, an entropy encoding unit 155, and an inverse quantization unit. 160, an inverse transform unit 165, an adder 170, a loop filter unit 180, and a memory 190.

Each component of the image encoding device may be implemented as hardware or software, or as a combination of hardware and software. Also, the function of each component may be implemented as software, and the microprocessor may be implemented to execute the software function corresponding to each component.

One image (video) is composed of one or more sequences including a plurality of pictures. Each picture is divided into a plurality of areas and encoding is performed for each area. For example, one picture is divided into one or more tiles or/and slices. Here, one or more tiles may be defined as a tile group. Each tile or/slice is divided into one or more Coding Tree Units (CTUs). And each CTU is divided into one or more CUs (Coding Units) by a tree structure. Information applied to each CU is coded as a CU syntax, and information commonly applied to CUs included in one CTU is coded as a CTU syntax. In addition, information commonly applied to all blocks in one slice is coded as syntax of a slice header, and information applied to all blocks constituting one or more pictures is a picture parameter set (PPS) or picture coded in the header. Furthermore, information commonly referred to by a plurality of pictures is coded into a Sequence Parameter Set (SPS). Also, information commonly referred to by one or more SPSs is coded into a video parameter set (VPS). Also, information commonly applied to one tile or tile group may be encoded as syntax of a tile or tile group header. Syntax included in the SPS, PPS, slice header, tile or tile group header may be referred to as high level syntax.

The picture divider 110 determines the size of a coding tree unit (CTU). Information on the size of the CTU (CTU size) is encoded as SPS or PPS syntax and transmitted to the video decoding apparatus.

The picture division unit 110 divides each picture constituting an image into a plurality of Coding Tree Units (CTUs) having a predetermined size, and then iteratively divides the CTUs using a tree structure. Divide (recursively). A leaf node in the tree structure becomes a coding unit (CU), which is a basic unit of encoding.

As a tree structure, a quad tree (QT) in which a parent node (or parent node) is divided into four subnodes (or child nodes) of the same size, or a binary tree (BinaryTree) in which a parent node is divided into two subnodes , BT), or a TernaryTree (TT) in which a parent node is split into three subnodes at a ratio of 1:2:1, or a structure in which two or more of these QT structures, BT structures, and TT structures are mixed. there is. For example, a QuadTree plus BinaryTree (QTBT) structure may be used, or a QuadTree plus BinaryTree TernaryTree (QTBTTT) structure may be used. Here, BTTT may be combined to be referred to as MTT (Multiple-Type Tree).

2 is a diagram for explaining a method of dividing a block using a QTBTTT structure.

As shown in FIG. 2, the CTU may first be divided into QT structures. Quadtree splitting can be repeated until the size of the splitting block reaches the minimum block size (MinQTSize) of leaf nodes allowed by QT. A first flag (QT_split_flag) indicating whether each node of the QT structure is split into four nodes of a lower layer is encoded by the entropy encoder 155 and signaled to the video decoding device. If the leaf node of QT is not larger than the maximum block size (MaxBTSize) of the root node allowed in BT, it may be further divided into either a BT structure or a TT structure. A plurality of division directions may exist in the BT structure and/or the TT structure. For example, there may be two directions in which blocks of the corresponding node are divided horizontally and vertically. As shown in FIG. 2, when MTT splitting starts, a second flag (mtt_split_flag) indicating whether nodes are split, and if split, a flag indicating additional split direction (vertical or horizontal) and/or split type (Binary or Ternary) is encoded by the entropy encoding unit 155 and signaled to the video decoding apparatus.

Alternatively, prior to coding the first flag (QT_split_flag) indicating whether each node is split into four nodes of a lower layer, a CU split flag (split_cu_flag) indicating whether the node is split is coded. It could be. When the value of the CU split flag (split_cu_flag) indicates that it is not split, the block of the corresponding node becomes a leaf node in the split tree structure and becomes a coding unit (CU), which is a basic unit of encoding. When the value of the CU split flag (split_cu_flag) indicates splitting, the video encoding apparatus starts encoding from the first flag in the above-described manner.

As another example of a tree structure, when QTBT is used, the block of the corresponding node is divided into two blocks of the same size horizontally (i.e., symmetric horizontal splitting) and the type that splits vertically (i.e., symmetric vertical splitting). Branches may exist. A split flag (split_flag) indicating whether each node of the BT structure is split into blocks of a lower layer and split type information indicating a split type are encoded by the entropy encoder 155 and transmitted to the video decoding device. Meanwhile, a type in which a block of a corresponding node is divided into two blocks having an asymmetric shape may additionally exist. The asymmetric form may include a form in which the block of the corresponding node is divided into two rectangular blocks having a size ratio of 1:3, or a form in which the block of the corresponding node is divided in a diagonal direction may be included.

A CU can have various sizes depending on the QTBT or QTBTTT split from the CTU. Hereinafter, a block corresponding to a CU to be encoded or decoded (ie, a leaf node of QTBTTT) is referred to as a 'current block'. Depending on the adoption of the QTBTTT division, the shape of the current block may be rectangular as well as square.

The prediction unit 120 predicts a current block and generates a prediction block. The prediction unit 120 includes an intra prediction unit 122 and an inter prediction unit 124 .

In general, each current block in a picture can be coded predictively. In general, prediction of a current block uses an intra-prediction technique (using data from a picture containing the current block) or an inter-prediction technique (using data from a picture coded before the picture containing the current block). can be performed Inter prediction includes both uni-prediction and bi-prediction.

The intra predictor 122 predicts pixels in the current block using pixels (reference pixels) located around the current block in the current picture including the current block. A plurality of intra prediction modes exist according to the prediction direction. For example, as shown in FIG. 3A, the plurality of intra prediction modes may include two non-directional modes including a planar mode and a DC mode and 65 directional modes. Depending on each prediction mode, the neighboring pixels to be used and the arithmetic expression are defined differently.

For efficient directional prediction of the rectangular current block, directional modes (numbers 67 to 80 and -1 to -14 intra prediction modes) indicated by dotted arrows in FIG. 3B may be additionally used. These may be referred to as “wide angle intra-prediction modes”. In FIG. 3B , arrows indicate corresponding reference samples used for prediction and do not indicate prediction directions. The prediction direction is opposite to the direction the arrow is pointing. Wide-angle intra prediction modes are modes that perform prediction in the opposite direction of a specific directional mode without additional bit transmission when the current block is rectangular. At this time, among the wide-angle intra prediction modes, some wide-angle intra prediction modes usable for the current block may be determined by the ratio of the width and height of the rectangular current block. For example, wide-angle intra prediction modes (67 to 80 intra prediction modes) having an angle smaller than 45 degrees are usable when the current block has a rectangular shape with a height smaller than a width, and a wide angle having an angle greater than -135 degrees. Intra prediction modes (-1 to -14 intra prediction modes) are available when the current block has a rectangular shape where the width is greater than the height.

The intra prediction unit 122 may determine an intra prediction mode to be used for encoding the current block. In some examples, the intra prediction unit 122 may encode the current block using several intra prediction modes and select an appropriate intra prediction mode to be used from the tested modes. For example, the intra predictor 122 calculates rate-distortion values using rate-distortion analysis for several tested intra-prediction modes, and has the best rate-distortion characteristics among the tested modes. Intra prediction mode can also be selected.

The intra prediction unit 122 selects one intra prediction mode from among a plurality of intra prediction modes, and predicts a current block using neighboring pixels (reference pixels) determined according to the selected intra prediction mode and an arithmetic expression. Information on the selected intra prediction mode is encoded by the entropy encoder 155 and transmitted to the video decoding apparatus.

The inter prediction unit 124 generates a prediction block for a current block using a motion compensation process. The inter-prediction unit 124 searches for a block most similar to the current block in the encoded and decoded reference picture prior to the current picture, and generates a prediction block for the current block using the searched block. Then, a motion vector (MV) corresponding to displacement between the current block in the current picture and the prediction block in the reference picture is generated. In general, motion estimation is performed on a luma component, and a motion vector calculated based on the luma component is used for both the luma component and the chroma component. Motion information including reference picture information and motion vector information used to predict the current block is encoded by the entropy encoding unit 155 and transmitted to the video decoding apparatus.

The inter-prediction unit 124 may perform interpolation on a reference picture or reference block in order to increase prediction accuracy. That is, subsamples between two consecutive integer samples are interpolated by applying filter coefficients to a plurality of consecutive integer samples including the two integer samples. When a process of searching for a block most similar to the current block is performed for the interpolated reference picture, the motion vector can be expressed with precision of decimal units instead of integer sample units. The precision or resolution of the motion vector may be set differently for each unit of a target region to be encoded, for example, a slice, tile, CTU, or CU. When such adaptive motion vector resolution (AMVR) is applied, information on motion vector resolution to be applied to each target region must be signaled for each target region. For example, when the target region is a CU, information on motion vector resolution applied to each CU is signaled. Information on the motion vector resolution may be information indicating the precision of differential motion vectors, which will be described later.

Meanwhile, the inter prediction unit 124 may perform inter prediction using bi-prediction. In the case of bi-directional prediction, two reference pictures and two motion vectors representing positions of blocks most similar to the current block within each reference picture are used. The inter prediction unit 124 selects a first reference picture and a second reference picture from reference picture list 0 (RefPicList0) and reference picture list 1 (RefPicList1), respectively, and searches for a block similar to the current block within each reference picture. A first reference block and a second reference block are generated. Then, a prediction block for the current block is generated by averaging or weighted averaging the first reference block and the second reference block. Further, motion information including information on two reference pictures used to predict the current block and information on two motion vectors is delivered to the encoder 150. Here, reference picture list 0 may include pictures prior to the current picture in display order among restored pictures, and reference picture list 1 may include pictures after the current picture in display order among restored pictures. there is. However, it is not necessarily limited to this, and in order of display, ups and downs pictures subsequent to the current picture may be additionally included in reference picture list 0, and conversely, ups and downs pictures prior to the current picture may be additionally included in reference picture list 1. may also be included.

Various methods may be used to minimize the amount of bits required to encode motion information.

For example, when the reference picture and motion vector of the current block are the same as those of the neighboring block, the motion information of the current block can be delivered to the video decoding apparatus by encoding information capable of identifying the neighboring block. This method is called 'merge mode'.

In the merge mode, the inter prediction unit 124 selects a predetermined number of merge candidate blocks (hereinafter referred to as 'merge candidates') from neighboring blocks of the current block.

Neighboring blocks for deriving merge candidates include a left block (A0), a lower left block (A1), an upper block (B0), and an upper right block (B1) adjacent to the current block in the current picture, as shown in FIG. ), and all or part of the upper left block A2 may be used. Also, a block located in a reference picture (which may be the same as or different from a reference picture used to predict the current block) other than the current picture in which the current block is located may be used as a merge candidate. For example, a block co-located with the current block in the reference picture or blocks adjacent to the co-located block may be additionally used as a merge candidate. If the number of merge candidates selected by the method described above is less than the preset number, a 0 vector is added to the merge candidates.

The inter prediction unit 124 constructs a merge list including a predetermined number of merge candidates using these neighboring blocks. Among the merge candidates included in the merge list, a merge candidate to be used as motion information of the current block is selected, and merge index information for identifying the selected candidate is generated. The generated merge index information is encoded by the encoder 150 and transmitted to the video decoding apparatus.

Merge skip mode is a special case of merge mode. After performing quantization, when all transform coefficients for entropy encoding are close to zero, only neighboring block selection information is transmitted without transmitting a residual signal. By using the merge skip mode, it is possible to achieve a relatively high encoding efficiency in low-motion images, still images, screen content images, and the like.

Hereinafter, merge mode and merge skip mode are collectively referred to as merge/skip mode.

Another method for encoding motion information is Advanced Motion Vector Prediction (AMVP) mode.

In the AMVP mode, the inter prediction unit 124 derives predictive motion vector candidates for the motion vector of the current block using neighboring blocks of the current block. Neighboring blocks used to derive predictive motion vector candidates include a left block A0, a lower left block A1, an upper block B0, and an upper right block adjacent to the current block in the current picture shown in FIG. B1), and all or part of the upper left block (A2) may be used. In addition, a block located in a reference picture (which may be the same as or different from the reference picture used to predict the current block) other than the current picture where the current block is located will be used as a neighboring block used to derive motion vector candidates. may be For example, a collocated block co-located with the current block within the reference picture or blocks adjacent to the collocated block may be used. If the number of motion vector candidates is smaller than the preset number according to the method described above, a 0 vector is added to the motion vector candidates.

The inter-prediction unit 124 derives predicted motion vector candidates using the motion vectors of the neighboring blocks, and determines a predicted motion vector for the motion vector of the current block using the predicted motion vector candidates. Then, a differential motion vector is calculated by subtracting the predicted motion vector from the motion vector of the current block.

The predicted motion vector may be obtained by applying a predefined function (eg, median value, average value operation, etc.) to predicted motion vector candidates. In this case, the video decoding apparatus also knows the predefined function. In addition, since a neighboring block used to derive a predicted motion vector candidate is a block that has already been encoded and decoded, the video decoding apparatus also knows the motion vector of the neighboring block. Therefore, the video encoding apparatus does not need to encode information for identifying a predictive motion vector candidate. Therefore, in this case, information on differential motion vectors and information on reference pictures used to predict the current block are encoded.

Meanwhile, the predicted motion vector may be determined by selecting one of the predicted motion vector candidates. In this case, along with information on differential motion vectors and information on reference pictures used to predict the current block, information for identifying the selected predictive motion vector candidate is additionally encoded.

The subtractor 130 subtracts the prediction block generated by the intra prediction unit 122 or the inter prediction unit 124 from the current block to generate a residual block.

The transform unit 140 transforms the residual signal in the residual block having pixel values in the spatial domain into transform coefficients in the frequency domain. The transform unit 140 may transform residual signals in the residual block by using the entire size of the residual block as a transform unit, or divide the residual block into a plurality of subblocks and use the subblocks as a transform unit to perform transformation. You may. Alternatively, the residual signals may be divided into two subblocks, a transform region and a non-transform region, and transform the residual signals using only the transform region subblock as a transform unit. Here, the transformation region subblock may be one of two rectangular blocks having a size ratio of 1:1 based on a horizontal axis (or a vertical axis). In this case, a flag (cu_sbt_flag) indicating that only subblocks have been transformed, directional (vertical/horizontal) information (cu_sbt_horizontal_flag), and/or location information (cu_sbt_pos_flag) are encoded by the entropy encoding unit 155 and signaled to the video decoding device. do. In addition, the size of the transform region subblock may have a size ratio of 1:3 based on the horizontal axis (or vertical axis), and in this case, a flag (cu_sbt_quad_flag) for distinguishing the corresponding division is additionally encoded by the entropy encoder 155 to obtain an image It is signaled to the decryption device.

Meanwhile, the transform unit 140 may individually transform the residual block in the horizontal direction and the vertical direction. For the transformation, various types of transformation functions or transformation matrices may be used. For example, a pair of transformation functions for horizontal transformation and vertical transformation may be defined as a multiple transform set (MTS). The transform unit 140 may select one transform function pair having the highest transform efficiency among the MTS and transform the residual blocks in the horizontal and vertical directions, respectively. Information (mts_idx) on a pair of transform functions selected from the MTS is encoded by the entropy encoding unit 155 and signaled to the video decoding device.

The quantization unit 145 quantizes transform coefficients output from the transform unit 140 using a quantization parameter, and outputs the quantized transform coefficients to the entropy encoding unit 155 . The quantization unit 145 may directly quantize a related residual block without transformation for a certain block or frame. The quantization unit 145 may apply different quantization coefficients (scaling values) according to positions of transform coefficients in the transform block. A quantization matrix applied to the two-dimensionally arranged quantized transform coefficients may be coded and signaled to the video decoding apparatus.

The rearrangement unit 150 may rearrange the coefficient values of the quantized residual values.

The reordering unit 150 may change a 2D coefficient array into a 1D coefficient sequence using coefficient scanning. For example, the reordering unit 150 may output a one-dimensional coefficient sequence by scanning DC coefficients to coefficients in a high frequency region using a zig-zag scan or a diagonal scan. . Depending on the size of the transformation unit and intra prediction mode, instead of zig-zag scan, vertical scan that scans a 2D coefficient array in a column direction and horizontal scan that scans 2D block-shaped coefficients in a row direction may be used. That is, a scan method to be used among zig-zag scan, diagonal scan, vertical scan, and horizontal scan may be determined according to the size of the transform unit and the intra prediction mode.

The entropy encoding unit 155 uses various encoding schemes such as CABAC (Context-based Adaptive Binary Arithmetic Code) and Exponential Golomb to convert the one-dimensional quantized transform coefficients output from the reordering unit 150 to each other. A bitstream is created by encoding the sequence.

In addition, the entropy encoding unit 155 encodes information such as CTU size, CU splitting flag, QT splitting flag, MTT splitting type, and MTT splitting direction related to block splitting so that the video decoding apparatus can divide the block in the same way as the video encoding apparatus. make it possible to divide In addition, the entropy encoding unit 155 encodes information about a prediction type indicating whether the current block is encoded by intra prediction or inter prediction, and encodes intra prediction information (ie, intra prediction) according to the prediction type. mode) or inter prediction information (motion information encoding mode (merge mode or AMVP mode), merge index in case of merge mode, reference picture index and differential motion vector information in case of AMVP mode) are encoded. Also, the entropy encoding unit 155 encodes information related to quantization, that is, information about quantization parameters and information about quantization matrices.

The inverse quantization unit 160 inversely quantizes the quantized transform coefficients output from the quantization unit 145 to generate transform coefficients. The inverse transform unit 165 transforms transform coefficients output from the inverse quantization unit 160 from a frequency domain to a spatial domain to restore a residual block.

The adder 170 restores the current block by adding the restored residual block and the predicted block generated by the predictor 120. Pixels in the reconstructed current block are used as reference pixels when intra-predicting the next block.

The loop filter unit 180 reconstructs pixels in order to reduce blocking artifacts, ringing artifacts, blurring artifacts, etc. caused by block-based prediction and transformation/quantization. perform filtering on The filter unit 180 is an in-loop filter and may include all or part of a deblocking filter 182, a sample adaptive offset (SAO) filter 184, and an adaptive loop filter (ALF) 186. .

The deblocking filter 182 filters the boundary between reconstructed blocks to remove blocking artifacts caused by block-by-block encoding/decoding, and the SAO filter 184 and alf 186 perform deblocking filtering. Additional filtering is performed on the image. The SAO filter 184 and the alf 186 are filters used to compensate for a difference between a reconstructed pixel and an original pixel caused by lossy coding. The SAO filter 184 improves not only subjective picture quality but also coding efficiency by applying an offset in units of CTUs. In contrast, the ALF 186 performs block-by-block filtering. Distortion is compensated for by applying different filters by distinguishing the edge of the corresponding block and the degree of change. Information on filter coefficients to be used for ALF may be coded and signaled to the video decoding apparatus.

The reconstruction block filtered through the deblocking filter 182, the SAO filter 184, and the ALF 186 is stored in the memory 190. When all blocks in one picture are reconstructed, the reconstructed picture can be used as a reference picture for inter-prediction of blocks in the picture to be encoded later.

5 is an exemplary block diagram of a video decoding apparatus capable of implementing the techniques of this disclosure. Hereinafter, referring to FIG. 5, a video decoding device and sub-elements of the device will be described.

The image decoding apparatus includes an entropy decoding unit 510, a rearrangement unit 515, an inverse quantization unit 520, an inverse transform unit 530, a prediction unit 540, an adder 550, a loop filter unit 560, and a memory ( 570) may be configured.

Like the image encoding device of FIG. 1 , each component of the image decoding device may be implemented as hardware or software, or a combination of hardware and software. Also, the function of each component may be implemented as software, and the microprocessor may be implemented to execute the software function corresponding to each component.

The entropy decoding unit 510 determines a current block to be decoded by extracting information related to block division by decoding the bitstream generated by the video encoding apparatus, and provides prediction information and residual signals necessary for restoring the current block. extract information, etc.

The entropy decoding unit 510 determines the size of the CTU by extracting information about the CTU size from a sequence parameter set (SPS) or a picture parameter set (PPS), and divides the picture into CTUs of the determined size. Then, the CTU is divided using the tree structure by determining the CTU as the top layer of the tree structure, that is, the root node, and extracting division information for the CTU.

For example, when a CTU is split using the QTBTTT structure, a first flag (QT_split_flag) related to splitting of QT is first extracted and each node is split into four nodes of a lower layer. In addition, for a node corresponding to a leaf node of QT, a second flag (MTT_split_flag) related to splitting of MTT and split direction (vertical / horizontal) and / or split type (binary / ternary) information are extracted and the corresponding leaf node is MTT split into structures Accordingly, each node below the leaf node of QT is recursively divided into a BT or TT structure.

As another example, when a CTU is split using the QTBTTT structure, a CU split flag (split_cu_flag) indicating whether the CU is split is first extracted, and when the corresponding block is split, a first flag (QT_split_flag) is extracted. may be During the splitting process, each node may have zero or more iterative MTT splits after zero or more repetitive QT splits. For example, the CTU may immediately undergo MTT splitting, or conversely, only QT splitting may occur multiple times.

As another example, when a CTU is split using a QTBT structure, a first flag (QT_split_flag) related to QT splitting is extracted and each node is split into four nodes of a lower layer. And, for a node corresponding to a leaf node of QT, a split flag (split_flag) indicating whether to further split into BTs and split direction information are extracted.

Meanwhile, when the entropy decoding unit 510 determines a current block to be decoded by using tree structure partitioning, it extracts information about a prediction type indicating whether the current block is intra-predicted or inter-predicted. When the prediction type information indicates intra prediction, the entropy decoding unit 510 extracts syntax elements for intra prediction information (intra prediction mode) of the current block. When the prediction type information indicates inter prediction, the entropy decoding unit 510 extracts syntax elements for the inter prediction information, that is, information indicating a motion vector and a reference picture to which the motion vector refers.

In addition, the entropy decoding unit 510 extracts quantization-related information and information about quantized transform coefficients of the current block as information about the residual signal.

The reordering unit 515 converts the sequence of 1-dimensional quantized transform coefficients entropy-decoded in the entropy decoding unit 510 into a 2-dimensional coefficient array (ie, in the reverse order of the coefficient scanning performed by the image encoding apparatus). block) can be changed.

The inverse quantization unit 520 inverse quantizes the quantized transform coefficients and inverse quantizes the quantized transform coefficients using a quantization parameter. The inverse quantization unit 520 may apply different quantization coefficients (scaling values) to the two-dimensionally arranged quantized transform coefficients. The inverse quantization unit 520 may perform inverse quantization by applying a matrix of quantization coefficients (scaling values) from the image encoding device to a 2D array of quantized transformation coefficients.

The inverse transform unit 530 inversely transforms the inverse quantized transform coefficients from the frequency domain to the spatial domain to restore residual signals, thereby generating a residual block for the current block.

In addition, when the inverse transform unit 530 inverse transforms only a partial region (subblock) of a transform block, a flag (cu_sbt_flag) indicating that only a subblock of the transform block has been transformed, and direction information (vertical/horizontal) information (cu_sbt_horizontal_flag) of the transform block ) and/or the location information (cu_sbt_pos_flag) of the subblock, and inversely transforms the transform coefficients of the corresponding subblock from the frequency domain to the spatial domain to restore the residual signals. By filling , the final residual block for the current block is created.

In addition, when the MTS is applied, the inverse transform unit 530 determines transform functions or transform matrices to be applied in the horizontal and vertical directions, respectively, using MTS information (mts_idx) signaled from the video encoding device, and uses the determined transform functions. Inverse transform is performed on the transform coefficients in the transform block in the horizontal and vertical directions.

The prediction unit 540 may include an intra prediction unit 542 and an inter prediction unit 544 . The intra prediction unit 542 is activated when the prediction type of the current block is intra prediction, and the inter prediction unit 544 is activated when the prediction type of the current block is inter prediction.

The intra prediction unit 542 determines the intra prediction mode of the current block among a plurality of intra prediction modes from the syntax element for the intra prediction mode extracted from the entropy decoding unit 510, and references the current block according to the intra prediction mode. The current block is predicted using pixels.

The inter prediction unit 544 determines the motion vector of the current block and the reference picture referred to by the motion vector by using the syntax element for the inter prediction mode extracted from the entropy decoding unit 510, and converts the motion vector and the reference picture. to predict the current block.

The adder 550 restores the current block by adding the residual block output from the inverse transform unit and the prediction block output from the inter prediction unit or intra prediction unit. Pixels in the reconstructed current block are used as reference pixels when intra-predicting a block to be decoded later.

The loop filter unit 560 may include a deblocking filter 562, an SAO filter 564, and an ALF 566 as in-loop filters. The deblocking filter 562 performs deblocking filtering on boundaries between reconstructed blocks in order to remove blocking artifacts generated by block-by-block decoding. The SAO filter 564 and the ALF 566 perform additional filtering on the reconstructed block after deblocking filtering to compensate for the difference between the reconstructed pixel and the original pixel caused by lossy coding. ALF filter coefficients are determined using information on filter coefficients decoded from the non-stream.

The reconstruction block filtered through the deblocking filter 562, the SAO filter 564, and the ALF 566 is stored in the memory 570. When all blocks in one picture are reconstructed, the reconstructed picture is used as a reference picture for inter-prediction of blocks in the picture to be encoded later.

6 is a diagram for explaining a method of generating a prediction block of a current block in a combined inter/intra prediction (CIIP) mode. The intra-prediction mode may correspond to the same meaning as the intra-prediction mode. The intra-prediction mode and the intra-prediction mode may be mixed. The inter prediction mode may correspond to the same meaning as the inter prediction mode. Inter-prediction mode and inter-prediction mode may be mixed. The combined intra-picture inter-prediction mode may have the same meaning as the combined intra-inter prediction mode. Inter-screen prediction mode within a combined picture and CIIP mode can be mixed. In CIIP mode, inter prediction blocks can be generated in the same way as in normal merge mode. The intra-prediction block may be generated by applying a planar mode to reference pixels adjacent to the periphery of the current block. A final CIIP-based prediction block may be generated by applying a weight value to the generated inter-prediction block and intra-prediction block.

의 수학식을 이용하여 생성될 수 있다.Referring to FIG. 6 , a reference block (P _inter ) in a reference picture may be derived based on a merge mode. An intra prediction block (P _Planar ) may be generated by applying a planar mode to reference pixels adjacent to the current block. A CIIP-based prediction block (P _CIIP ) may be generated by applying a weight value to a corresponding reference block (P _inter ) and an intra prediction block (P _Planar ). A weight value applied to the reference block P _inter may correspond to W _inter . A weight value applied to the intra prediction block (P _Planar ) may correspond to W _intra . The prediction block based on CIIP (P _CIIP ) is

It can be generated using the equation of

7 is a diagram for describing neighboring blocks referred to for determining weight values in a combined intra-picture inter-prediction mode according to an embodiment of the present disclosure. In the CIIP mode, a weight value may be determined by considering whether neighboring blocks adjacent to the current block are coded in an intra prediction mode.

Referring to FIG. 7 , in CIIP mode, a weight value may be determined by considering whether an upper neighboring block A and a left neighboring block L adjacent to a current block are coded in an intra prediction mode.

8 is a diagram for explaining a method of determining a weight value in a combined intra-screen inter-prediction mode according to an embodiment of the present disclosure. If neighboring blocks adjacent to the current block encode many intra-prediction modes, a large weight value may be assigned to the intra-prediction block. Conversely, if neighboring blocks adjacent to the current block encode fewer intra-prediction modes, a smaller weight value may be assigned to the intra-prediction block.

Referring to FIG. 8 , when the upper neighboring block A and the left neighboring block L of the current block in FIG. 7 encode the intra prediction mode, a weight value assigned to the intra prediction block may correspond to 3. When the upper neighboring block A encodes the intra prediction mode and the left neighboring block L does not encode the intra prediction mode, a weight value assigned to the intra prediction block may correspond to 2. When the upper neighboring block A does not encode the intra prediction mode and the left neighboring block L encodes the intra prediction mode, a weight value assigned to the intra prediction block may correspond to 2. When the upper neighboring block A does not encode the intra prediction mode and the left neighboring block L does not encode the intra prediction mode, a weight assigned to the intra prediction block may correspond to 1.

9 is a diagram for explaining a method of applying a geometric division mode to a 32x32 block according to an embodiment of the present disclosure. Referring to the geometric division mode, one coding unit may be divided into two regions by a straight division boundary. The two divided regions may perform inter prediction using different motion information. Inter prediction blocks for the two divided regions may be respectively generated. A weighted average of the two generated inter prediction blocks may be used to generate a final geometric partitioning mode prediction block. The geometric segmentation mode sets the segmentation boundary area defined by a straight line using angle parameters and distance parameters. A weighted average may have the same meaning as a weighted sum.

Referring to FIG. 9 , a 32x32 block may be divided into two regions. Inter prediction may be performed on each of the two divided regions. φ may correspond to an angular parameter. ρ may correspond to a distance parameter. A straight line dividing a 32x32 block can be set using the angle parameter and the distance parameter.

10A and 10B are diagrams for explaining an angle parameter and a distance parameter in a geometric segmentation mode according to an embodiment of the present disclosure.

Referring to FIG. 10A , an angle parameter may be defined as a total of 20 quantized angles by symmetrically dividing a range of 360 degrees within a coding unit.

Referring to FIG. 10B, a distance parameter may be defined as four quantized distances. Among a total of 80 splitting directions that can occur as a combination of angle parameters and distance parameters, 10 overlapping splitting directions and 6 overlapping splitting directions with binary tree splitting and ternary tree splitting can be excluded. Accordingly, the geometric segmentation mode can use a total of 64 segmentation directions.

11 is a diagram for explaining a lookup table of segmentation direction information in a geometric segmentation mode according to an embodiment of the present disclosure. The combination of angle parameters and distance parameters can be defined as a look-up table. Splitting direction information may be transmitted for each coding unit. In the geometric partitioning mode, a merge candidate list for the geometric partitioning mode including only unidirectional motion information may be constructed from a general merge candidate list. Accordingly, motion information encoding can be simplified and the number of possible combinations can be reduced. A merge index used for each partition region may be transmitted using a merge candidate list for a geometric partition mode.

Referring to FIG. 11 , division direction information (e.g., merge_gpm_partition_idx) may be determined according to information on an angle parameter (e.g., angleIdx) and information on a distance parameter (e.g., distanceIdx). merge_gpm_partition_idx according to the combination of angleIdx and distanceIdx may be defined as a lookup table. The value of merge_gpm_partition_idx may range from 0 to 63. merge_gpm_partition_idx may be transmitted for each coding unit.

12 is a diagram for explaining direction information of a motion vector difference according to an embodiment of the present disclosure. In a general merge mode, motion information of a merge candidate list is used as motion information of a current block, and additional motion information is not transmitted. The general merge mode has the advantage of minimizing the amount of bits, but has a limitation that it cannot express optimal motion information. Merge with Motion Vector Difference (MMVD) using motion vector difference can correct motion information by adding the motion vector difference to the motion vector derived by the normal merge mode.

Merge mode using motion vector difference uses only the first and second candidates from the candidate list of normal merge mode to reduce complexity. One candidate is selected from two candidates, and a motion vector of the candidate may be set as an initial motion vector. The final motion vector may be determined by adding the additionally transmitted motion vector difference information to the initial motion vector. The motion vector difference information may include direction information and distance information.

Referring to FIG. 12 , direction information of a motion vector difference may only be corrected in a vertical or horizontal direction. Direction information of the motion vector difference may be composed of four directions. Index 0 may be assigned to direction information of a motion vector difference corrected by +1 in the horizontal direction and 0 in the vertical direction. Index 1 may be assigned to direction information of a motion vector difference corrected by -1 in the horizontal direction and 0 in the vertical direction. Index 2 may be assigned to direction information of a motion vector difference corrected by 0 in the horizontal direction and by +1 in the vertical direction. An index of 3 may be assigned to direction information of a motion vector difference corrected by 0 in the horizontal direction and -1 in the vertical direction.

13 is a diagram for explaining distance information of a motion vector difference according to an embodiment of the present disclosure.

Referring to FIG. 13 , distance information of a motion vector difference may include a luminance pixel distance, which is a motion distance. The direction information of the motion vector difference may consist of 8 types of motion distances. Index 0 may be assigned to distance information of a motion vector difference having a luminance pixel distance of 1/4. Index 1 may be assigned to distance information of a motion vector difference having a luminance pixel distance of 1/2. An index of 2 may be assigned to distance information of a motion vector difference having a luminance pixel distance of 1. An index of 3 may be assigned to distance information of a motion vector difference having a luminance pixel distance of 2. Index 4 may be assigned to distance information of a motion vector difference having a luminance pixel distance of 4. An index of 5 may be assigned to distance information of a motion vector difference having a luminance pixel distance of 8. An index of 6 may be assigned to distance information of a motion vector difference having a luminance pixel distance of 16. An index of 7 may be assigned to distance information of a motion vector difference having a luminance pixel distance of 32.

14 is a diagram for explaining a flowchart of applying inter prediction according to an embodiment of the present disclosure.

Referring to FIG. 14 , it may be determined whether the SKIP mode is applied (S1410). When it is determined that the SKIP mode is applied (S1410-YES), the SKIP mode may be applied (S1420). When it is determined that the SKIP mode is not applied (S1410-NO), it may be determined whether the merge mode is applied (S1430). When it is determined that the merge mode is not applied (S1430-NO), an adaptive motion vector prediction (AMVP) mode may be applied (S1440). When it is determined that the merge mode is applied (S1430-YES), it may be determined whether the merge mode is applied to the sub-block (S1450). When it is determined that the merge mode is applied to the sub-block (S1450-YES), the merge mode may be applied to the sub-block (S1460). Sub-block based temporal motion vector prediction and AFFINE merge mode may be applied. When it is determined that the merge mode is not applied to the sub-block (S1450-NO), it may be determined whether a general merge mode is applied (S1470).

When it is determined that the general merge mode is not applied (S1470-NO), it may be determined whether the CIIP mode is applied (S1480). When it is determined that the CIIP mode is not applied (S1480-NO), the geometric segmentation mode may be applied (S1481). If it is determined that the CIIP mode is applied (S1480-YES), the CIIP mode may be applied (S1482). When it is determined that a general merge mode is applied (S1470-YES), it may be determined whether a merge mode using a motion vector difference is applied (S1490). When it is determined that the merge mode using the motion vector difference is applied (S1490-YES), the merge mode using the motion vector difference can be applied (S1491). When it is determined that the merge mode using the motion vector difference is not applied (S1490-NO), a general merge mode may be applied (S1492).

15 is a diagram for explaining a flowchart of applying a new mode in inter prediction according to an embodiment of the present disclosure. When the normal merge mode, rather than the sub-block merge mode, is applied to the current block, whether or not the current block is divided may be checked. After that, the prediction method of the current block can be confirmed. As a prediction method of the current block, an intra-prediction method and an inter-prediction method may exist. Finally, it can be checked whether motion vector difference is used. Whether to correct motion information may be determined by checking whether motion vector difference is used.

Referring to FIG. 15 , it may be determined whether merge mode is applied to a sub-block (S1510). When it is determined that the merge mode is applied to the sub-block (S1510-YES), the merge mode may be applied to the sub-block (S1520). Sub-block based temporal motion vector prediction and AFFINE merge mode may be applied. When it is determined that the merge mode is not applied to the sub-block (S1510-NO), it may be determined whether the geometric division mode is applied (S1530). When it is determined that the geometric segmentation mode is applied (S1530-YES), it may be determined whether the CIIP mode is applied (S1540). When it is determined that the CIIP mode is applied (S1540-YES), it may be determined whether a merge mode using a motion vector difference is applied (S1541). If it is determined that the merge mode using the motion vector difference is applied (S1541-YES), a new mode combining the geometric segmentation mode, the CIIP mode, and the merge mode using the motion vector difference can be applied (S1542). When it is determined that the merge mode using the motion vector difference is not applied (S1541-NO), a new mode combining the geometric segmentation mode and the CIIP mode may be applied (S1543).

When it is determined that the CIIP mode is not applied (S1540-NO), it may be determined whether a merge mode using a motion vector difference is applied (S1544). If it is determined that the merge mode using the motion vector difference is applied (S1544-YES), a new mode combining the geometric division mode and the merge mode using the motion vector difference may be applied (S1545). When it is determined that the merge mode using the motion vector difference is not applied (S1544-NO), the geometric segmentation mode may be applied (S1546).

When it is determined that the geometric segmentation mode is not applied (S1530-NO), it may be determined whether the CIIP mode is applied (S1550). When it is determined that the CIIP mode is applied (S1550-YES), it may be determined whether a merge mode using a motion vector difference is applied (S1551). If it is determined that the merge mode using the motion vector difference is applied (S1551-YES), a new mode combining the CIIP mode and the merge mode using the motion vector difference can be applied (S1552). When it is determined that merge mode using motion vector difference is not applied (S1551-NO), CIIP mode may be applied (S1553).

When it is determined that the CIIP mode is not applied (S1550-NO), it may be determined whether a merge mode using a motion vector difference is applied (S1554). When it is determined that merge mode using motion vector difference is applied (S1554-YES), merge mode using motion vector difference may be applied (S1555). When it is determined that the merge mode using the motion vector difference is not applied (S1554-NO), the normal merge mode may be applied (S1556).

16 is a diagram for explaining a flowchart for applying a new mode in inter prediction according to another embodiment of the present disclosure.

Referring to FIG. 16 , it may be determined whether merge mode is applied to a sub-block (S1610). When it is determined that the merge mode is applied to the sub-block (S1610-YES), the merge mode may be applied to the sub-block (S1620). Sub-block based temporal motion vector prediction and AFFINE merge mode may be applied. When it is determined that the merge mode is not applied to the sub-block (S1610-NO), it may be determined whether the geometric division mode is applied (S1630). When it is determined that the geometric segmentation mode is applied (S1630-YES), it may be determined whether the CIIP mode is applied (S1640). When it is determined that the CIIP mode is applied (S1640-YES), a new mode combining the geometric division mode and the CIIP mode may be applied (S1641).

When it is determined that the CIIP mode is not applied (S1640-NO), it may be determined whether a merge mode using a motion vector difference is applied (S1642). When it is determined that the merge mode using the motion vector difference is applied (S1642-YES), a new mode combining the geometric division mode and the merge mode using the motion vector difference may be applied (S1643). When it is determined that the merge mode using the motion vector difference is not applied (S1642-NO), the geometric segmentation mode may be applied (S1644).

When it is determined that the geometric segmentation mode is not applied (S1630-NO), it may be determined whether the CIIP mode is applied (S1650). If it is determined that the CIIP mode is applied (S1650-YES), the CIIP mode may be applied (S1651). When it is determined that the CIIP mode is not applied (S1650-NO), it may be determined whether a merge mode using a motion vector difference is applied (S1652). When it is determined that merge mode using motion vector difference is applied (S1652-YES), merge mode using motion vector difference may be applied (S1653). When it is determined that the merge mode using the motion vector difference is not applied (S1652-NO), the normal merge mode may be applied (S1654).

17 is a diagram for explaining a flowchart of applying a new mode in inter prediction according to another embodiment of the present disclosure.

Referring to FIG. 17 , it may be determined whether merge mode is applied to a sub-block (S1710). When it is determined that the merge mode is applied to the sub-block (S1710-YES), the merge mode may be applied to the sub-block (S1720). Sub-block based temporal motion vector prediction and AFFINE merge mode may be applied. When it is determined that the merge mode is not applied to the sub-block (S1710-NO), it may be determined whether the normal merge mode is applied (S1730). When it is determined that the normal merge mode is not applied (S1730-NO), it may be determined whether the CIIP mode is applied (S1740). When it is determined that the CIIP mode is not applied (S1740-NO), it may be determined whether a new mode combining a geometric segmentation mode and a merge mode using motion vector difference is applied (S1741). When it is determined that the new mode combining the geometric segmentation mode and the merge mode using the motion vector difference is not applied (S1741-NO), the geometric segmentation mode may be applied (S1742). If it is determined that a new mode combining the geometric segmentation mode and the merge mode using the motion vector difference is applied (S1741-YES), a new mode combining the geometric segmentation mode and the merge mode using the motion vector difference may be applied (S1743). .

If it is determined that the CIIP mode is applied (S1740-YES), it may be determined whether a new mode combining the geometric division mode and the CIIP mode is applied (S1744). When it is determined that the new mode combining the geometric partitioning mode and the CIIP mode is not applied (S1744-NO), the CIIP mode may be applied (S1745). When it is determined that a new mode combining the geometric division mode and the CIIP mode is applied (S1744-YES), a new mode combining the geometric division mode and the CIIP mode may be applied (S1746).

When it is determined that the normal merge mode is applied (S1730-YES), it may be determined whether the merge mode using the motion vector difference is applied (S1750). When it is determined that the merge mode using the motion vector difference is applied (S1750-YES), it may be determined whether a new mode combining the CIIP mode and the merge mode using the motion vector difference is applied (S1751). When it is determined that the new mode combining the CIIP mode and the merge mode using the motion vector difference is not applied (S1751-NO), the merge mode using the motion vector difference can be applied (S1752). If it is determined that a new mode combining CIIP mode and merge mode using motion vector difference is applied (S1751-YES), a new mode combining CIIP mode and merge mode using motion vector difference can be applied (S1753). When it is determined that the merge mode using the motion vector difference is not applied (S1750-NO), the normal merge mode may be applied (S1754).

18 is a diagram for explaining a new mode combining a geometric partitioning mode and a CIIP mode according to an embodiment of the present disclosure.

Referring to FIG. 18 , in a new mode combining geometric partitioning mode and CIIP mode, a current block can be divided into two regions by geometric partitioning mode. The two regions may correspond to the P1 region and the P2 region. The P1 region and the P2 region can independently generate inter prediction blocks using different motion information. A final inter-prediction block P _inter may be generated by performing a weighted average or a weighted sum of two independently generated inter-prediction blocks. The intra prediction block P _intra may be generated using the planner mode. The intra prediction block P _intra is derived using various methods such as a template based intra mode derivation (TIMD) method or a decoder side intra mode derivation (DIMD) method. It can be generated using intra prediction mode. The final prediction block P _pred may be generated by performing a weighted average or weighted sum of the final inter prediction block P _inter and the intra prediction block P _intra . Here, the weight value W _inter applied to the final inter prediction block P _inter and the weight value W _intra applied to the intra prediction block P _intra may be arbitrarily determined.

19 is a diagram for explaining a new mode combining a CIIP mode and a merge mode using motion vector difference according to an embodiment of the present disclosure.

Referring to FIG. 19, in a new mode combining CIIP mode and merge mode using motion vector difference, an inter prediction block P _inter uses corrected motion information generated by adding motion vector difference to a motion vector derived from merge mode. can be created The intra prediction block P _intra may be generated using the planner mode. The intra-prediction block P _intra may be generated using an intra-prediction mode derived using various methods, such as a template-based intra-prediction mode derivation method or an intra-prediction mode derivation method in a decoder. The final prediction block P _pred may be generated by performing a weighted average or weighted sum of the inter prediction block P _inter and the intra prediction block P _intra . Here, the weight value W _inter applied to the inter prediction block P _inter and the weight value W intra applied to the _intra prediction block P _intra may be arbitrarily determined.

20 is a diagram for explaining a new mode in which a geometric division mode and a merge mode using motion vector difference are combined according to an embodiment of the present disclosure.

Referring to FIG. 20 , in a new mode combining a geometric segmentation mode and a merge mode using motion vector difference, a current block can be divided into two regions by the geometric segmentation mode. The two regions may correspond to the P1 region and the P2 region. Motion information of the P1 area and motion information of the P2 area may be corrected by using the same motion vector difference information for the P1 area and the P2 area. Motion information of the P1 area and motion information of the P2 area may be corrected by using different motion vector difference information for the P1 area and the P2 area. In the P1 region and the P2 region, two inter-prediction blocks may be independently generated using corrected motion information. A final inter prediction block P _inter may be generated by performing a weighted average or a weighted sum of two independently generated inter prediction blocks. The final inter prediction block P _inter and the final prediction block P _pred may be the same.

21 is a diagram for explaining a new mode combining a geometric division mode, a CIIP mode, and a merge mode using a motion vector difference according to an embodiment of the present disclosure.

Referring to FIG. 21 , in a new mode combining geometric partitioning mode, CIIP mode, and merge mode using motion vector difference, a current block can be divided into two regions by geometric partitioning mode. The two regions may correspond to the P1 region and the P2 region. Motion information of the P1 area and motion information of the P2 area may be corrected by using the same motion vector difference information for the P1 area and the P2 area. Motion information of the P1 area and motion information of the P2 area may be corrected by using different motion vector difference information for the P1 area and the P2 area. In the P1 region and the P2 region, two inter-prediction blocks may be independently generated using corrected motion information. A final inter prediction block P _inter may be generated by performing a weighted average or a weighted sum of two independently generated inter prediction blocks.

The intra prediction block P _intra may be generated using the planner mode. The intra-prediction block P _intra may be generated using an intra-prediction mode derived using various methods, such as a template-based intra-prediction mode derivation method or an intra-prediction mode derivation method in a decoder. The final prediction block P _pred may be generated by performing a weighted average or weighted sum of the final inter prediction block P _inter and the intra prediction block P _intra . Here, the weight value W _inter applied to the final inter prediction block P _inter and the weight value W _intra applied to the intra prediction block P _intra may be arbitrarily determined.

Motion vector correction in the decoding device (Decoder side Motion Vector Refinement, DMVR ) and bidirectional optical flow ( Bi Method for correcting motion vectors based on -Directional Optical Flow (BDOF)

The DMVR method may correspond to a method of correcting a bidirectional motion vector predicted by a normal merge mode through motion vector search based on bilateral matching (BM) in a decoding process. The DMVR method can be performed when the current block is decoded in the normal merge mode. A method of correcting a motion vector based on BDOF may correspond to a method of finding an optimal motion vector in units of 4x4 subblocks using bidirectional motion vectors and performing prediction based on the optimal motion vector. A method of correcting a motion vector based on BDOF may be performed when a current block is decoded using a normal merge mode or a merge mode using a motion vector difference.

In FIG. 15 , when the merge mode using the motion vector difference is applied (S1555), a motion vector correction method based on BDOF may be applied. When the normal merge mode is applied in FIG. 15 (S1556), a motion vector correction method based on the DMVR method and BDOF may be applied. However, the present disclosure is not limited to these examples. The motion vector correction method based on the DMVR method and the BDOF method can be applied even when an arbitrary merge mode is applied.

22 is a diagram for explaining a video decoding process according to an embodiment of the present disclosure.

Referring to FIG. 22 , the decoding apparatus may determine a first mode based on at least one of a CIIP mode, a geometric segmentation mode, and a merge mode using motion vector difference (S2210). The decoding device may determine a motion vector from the merge candidate list (S2220). The decoding apparatus may generate a prediction block of the current block based on the first mode and the motion vector (S2230).

When the first mode is a mode in which the CIIP mode and the geometric segmentation mode are combined, determining motion vectors from the merge candidate list may include determining motion vectors for each of the two regions divided from the merge candidate list. . When the first mode is a mode in which the CIIP mode and the geometric segmentation mode are combined, the step of generating a prediction block of the current block is based on the two divided regions and the motion vectors for each of the two divided regions. generating a final inter-prediction block, generating an intra-prediction block for the current block based on at least one reference pixel adjacent to the current block, and predicting the current block by performing a weighted average of the final inter-prediction block and the intra-prediction block It may include creating a block.

Generating the final inter-prediction block for the current block includes generating an inter-prediction block for each of the two divided regions using motion vectors for each of the two divided regions, and and generating a final inter prediction block for the current block by combining or weighting the inter prediction blocks for the current block.

When the first mode is a mode in which the CIIP mode and the merge mode using motion vector difference are combined, generating the prediction block of the current block includes generating an inter prediction block for the current block based on the corrected motion vector, The method may include generating an intra prediction block for the current block based on at least one reference pixel adjacent to the block, and generating a prediction block of the current block by performing a weighted average of the inter prediction block and the intra prediction block. A corrected motion vector may be generated based on the motion vector and motion vector difference information.

When the first mode is a mode in which a geometric segmentation mode and a merge mode using motion vector difference are combined, the step of determining a motion vector from the merge candidate list is the step of determining motion vectors for each of the two regions divided from the merge candidate list. can include When the first mode is a mode in which a geometric segmentation mode and a merge mode using motion vector difference are combined, the step of generating a prediction block of the current block generates an inter prediction block for each of the two divided regions using the corrected motion vector. and generating a prediction block of the current block by combining or weighted averaging inter prediction blocks for each of the two divided regions. The corrected motion vector may be generated based on motion vectors for each of the two divided regions and motion vector difference information.

When the first mode is a combination of the CIIP mode, the geometric segmentation mode, and the merge mode using motion vector difference, the step of determining a motion vector from the merge candidate list determines the motion vectors for each of the two regions divided from the merge candidate list. It may include a decision-making step. When the first mode is a combination of the CIIP mode, the geometric segmentation mode, and the merge mode using motion vector difference, the step of generating a prediction block of the current block includes the two divided regions and the corrected values for each of the two divided regions. Generating a final inter-prediction block for the current block based on the motion vector, generating an intra-prediction block for the current block based on one or more reference pixels adjacent to the current block, and generating the final inter-prediction block and intra-prediction block Generating a prediction block of the current block by performing a weighted average of the prediction blocks. The corrected motion vector may be generated based on motion vectors for each of the two divided regions and motion vector difference information.

The step of generating the final inter-prediction block for the current block includes generating an inter-prediction block for each of the two divided regions using the corrected motion vector for each of the two divided regions and each of the two divided regions. and generating a final inter-prediction block for the current block by combining or weighting the inter-prediction blocks for .

23 is a diagram for explaining a video encoding process according to an embodiment of the present disclosure.

Referring to FIG. 23 , the encoding apparatus may determine a first mode based on at least one of a CIIP mode, a geometric segmentation mode, and a merge mode using motion vector difference (S2310). The encoding device may determine a motion vector from the merge candidate list (S2320). The encoding device may generate a prediction block of the current block based on the first mode and the motion vector (S2330).

When the first mode is a mode in which the CIIP mode and the geometric segmentation mode are combined, determining motion vectors from the merge candidate list may include determining motion vectors for each of the two regions divided from the merge candidate list. . When the first mode is a mode in which the CIIP mode and the geometric segmentation mode are combined, the step of generating a prediction block of the current block is based on the two divided regions and the motion vectors for each of the two divided regions. generating a final inter-prediction block, generating an intra-prediction block for the current block based on at least one reference pixel adjacent to the current block, and predicting the current block by performing a weighted average of the final inter-prediction block and the intra-prediction block It may include creating a block.

Generating the final inter-prediction block for the current block includes generating an inter-prediction block for each of the two divided regions using motion vectors for each of the two divided regions, and and generating a final inter prediction block for the current block by combining or weighting the inter prediction blocks for the current block.

When the first mode is a mode in which the CIIP mode and the merge mode using motion vector difference are combined, generating the prediction block of the current block includes generating an inter prediction block for the current block based on the corrected motion vector, The method may include generating an intra prediction block for the current block based on at least one reference pixel adjacent to the block, and generating a prediction block of the current block by performing a weighted average of the inter prediction block and the intra prediction block. A corrected motion vector may be generated based on the motion vector and motion vector difference information.

When the first mode is a mode in which a geometric division mode and a merge mode using motion vector difference are combined, the step of determining a motion vector from the merge candidate list is the step of determining motion vectors for each of the two regions divided from the merge candidate list. can include When the first mode is a mode in which a geometric segmentation mode and a merge mode using motion vector difference are combined, the step of generating a prediction block of the current block generates an inter prediction block for each of the two divided regions using the corrected motion vector. and generating a prediction block of the current block by combining or weighted averaging inter prediction blocks for each of the two divided regions. The corrected motion vector may be generated based on motion vectors for each of the two divided regions and motion vector difference information.

When the first mode is a combination of the CIIP mode, the geometric segmentation mode, and the merge mode using motion vector difference, the step of determining a motion vector from the merge candidate list determines the motion vectors for each of the two regions divided from the merge candidate list. It may include a decision-making step. When the first mode is a combination of the CIIP mode, the geometric segmentation mode, and the merge mode using motion vector difference, the step of generating a prediction block of the current block includes the two divided regions and the corrected values for each of the two divided regions. Generating a final inter-prediction block for the current block based on the motion vector, generating an intra-prediction block for the current block based on one or more reference pixels adjacent to the current block, and generating the final inter-prediction block and intra-prediction block Generating a prediction block of the current block by performing a weighted average of the prediction blocks. The corrected motion vector may be generated based on motion vectors for each of the two divided regions and motion vector difference information.

The step of generating the final inter-prediction block for the current block includes generating an inter-prediction block for each of the two divided regions using the corrected motion vector for each of the two divided regions and each of the two divided regions. and generating a final inter-prediction block for the current block by combining or weighting the inter-prediction blocks for .

In the flowchart/timing diagram of the present specification, it is described that each process is sequentially executed, but this is merely an example of the technical idea of one embodiment of the present disclosure. In other words, those skilled in the art to which an embodiment of the present disclosure belongs may change and execute the order described in the flowchart/timing diagram or perform one of each process within the range without departing from the essential characteristics of the embodiment of the present disclosure. Since it is possible to apply various modifications and variations by executing the above process in parallel, the flow chart/timing diagram is not limited to a time-series sequence.

In the above description, it should be understood that the exemplary embodiments may be implemented in many different ways. Functions or methods described in one or more examples may be implemented in hardware, software, firmware, or any combination thereof. It should be understood that the functional components described in this specification have been labeled "...unit" to particularly emphasize their implementation independence.

Meanwhile, various functions or methods described in this embodiment may be implemented as instructions stored in a non-transitory recording medium that can be read and executed by one or more processors. Non-transitory recording media include, for example, all types of recording devices in which data is stored in a form readable by a computer system. For example, the non-transitory recording medium includes storage media such as an erasable programmable read only memory (EPROM), a flash drive, an optical drive, a magnetic hard drive, and a solid state drive (SSD).

The above description is merely an example of the technical idea of the present embodiment, and various modifications and variations can be made to those skilled in the art without departing from the essential characteristics of the present embodiment. Therefore, the present embodiments are not intended to limit the technical idea of the present embodiment, but to explain, and the scope of the technical idea of the present embodiment is not limited by these embodiments. The scope of protection of this embodiment should be construed according to the claims below, and all technical ideas within the scope equivalent thereto should be construed as being included in the scope of rights of this embodiment.

122: intra prediction unit
510: entropy decoding unit
542: intra prediction unit

Claims (15)

determining a first mode based on at least one of a Combined Inter Intra Prediction (CIIP) mode, a geometric segmentation mode, and a merge mode using motion vector difference;
determining a motion vector from a merge candidate list; and
and generating a prediction block of a current block based on the first mode and the motion vector. According to claim 1,
When the first mode is a mode in which the CIIP mode and the geometric segmentation mode are combined, the step of determining a motion vector from the merge candidate list,
Determining a motion vector for each of the two divided regions in the merge candidate list;
When the first mode is a mode combining the CIIP mode and the geometric partitioning mode, generating a prediction block of the current block,
generating a final inter-prediction block for the current block based on the divided two regions and motion vectors for each of the divided regions;
generating an intra prediction block for the current block based on at least one reference pixel adjacent to the current block; and
and generating a prediction block of the current block by performing a weighted average of the final inter-prediction block and the intra-prediction block. According to claim 2,
Generating a final inter prediction block for the current block includes:
generating an inter-prediction block for each of the two divided regions by using a motion vector for each of the two divided regions; and
and generating a final inter-prediction block for the current block by combining or weighting-averaging inter-prediction blocks for each of the two divided regions. According to claim 1,
When the first mode is a mode in which the CIIP mode and the merge mode using the motion vector difference are combined, the generating of the prediction block of the current block comprises:
generating an inter prediction block for the current block based on the corrected motion vector;
generating an intra prediction block for the current block based on at least one reference pixel adjacent to the current block; and
Generating a prediction block of the current block by performing a weighted average of the inter-prediction block and the intra-prediction block;
The video decoding method of claim 1 , wherein the corrected motion vector is generated based on the motion vector and motion vector difference information. According to claim 1,
When the first mode is a mode in which the geometric division mode and the merge mode using the motion vector difference are combined, the step of determining a motion vector from the merge candidate list includes:
Determining a motion vector for each of the two divided regions in the merge candidate list;
When the first mode is a mode in which the geometric division mode and the merge mode using the motion vector difference are combined, generating a prediction block of the current block includes:
generating an inter prediction block for each of the two divided regions using the corrected motion vector; and
generating a prediction block of the current block by combining or weighted averaging inter prediction blocks for each of the two divided regions;
The corrected motion vector is generated based on a motion vector for each of the two divided regions and motion vector difference information. According to claim 1,
When the first mode is a mode in which the CIIP mode, the geometric partitioning mode, and the merge mode using the motion vector difference are combined, the step of determining a motion vector from the merge candidate list includes:
Determining a motion vector for each of the two divided regions in the merge candidate list;
When the first mode is a mode in which the CIIP mode, the geometric partitioning mode, and the merge mode using the motion vector difference are combined, generating a prediction block of the current block,
generating a final inter-prediction block for the current block based on the two divided regions and the corrected motion vectors for each of the divided two regions;
generating an intra prediction block for the current block based on at least one reference pixel adjacent to the current block; and
generating a prediction block of the current block by weighting averaging the final inter prediction block and the intra prediction block;
The corrected motion vector is generated based on a motion vector for each of the two divided regions and motion vector difference information. According to claim 6,
Generating a final inter prediction block for the current block includes:
generating an inter-prediction block for each of the two divided regions using a motion vector corrected for each of the two divided regions; and
and generating a final inter-prediction block for the current block by combining or weighting-averaging inter-prediction blocks for each of the two divided regions. determining a first mode based on at least one of a CIIP mode, a geometric segmentation mode, and a merge mode using motion vector difference;
determining a motion vector from a merge candidate list; and
and generating a prediction block of a current block based on the first mode and the motion vector. According to claim 8,
When the first mode is a mode in which the CIIP mode and the geometric segmentation mode are combined, the step of determining a motion vector from the merge candidate list,
Determining a motion vector for each of the two divided regions in the merge candidate list;
When the first mode is a mode combining the CIIP mode and the geometric partitioning mode, generating a prediction block of the current block,
generating a final inter-prediction block for the current block based on the divided two regions and motion vectors for each of the divided regions;
generating an intra prediction block for the current block based on at least one reference pixel adjacent to the current block; and
and generating a prediction block of the current block by performing a weighted average of the final inter-prediction block and the intra-prediction block. According to claim 9,
Generating a final inter prediction block for the current block includes:
generating an inter-prediction block for each of the two divided regions by using a motion vector for each of the two divided regions; and
and generating a final inter-prediction block for the current block by combining or weighting-averaging inter-prediction blocks for each of the two divided regions. According to claim 8,
When the first mode is a mode in which the CIIP mode and the merge mode using the motion vector difference are combined, the generating of the prediction block of the current block comprises:
generating an inter prediction block for the current block based on the corrected motion vector;
generating an intra prediction block for the current block based on at least one reference pixel adjacent to the current block; and
Generating a prediction block of the current block by performing a weighted average of the inter-prediction block and the intra-prediction block;
The video encoding method of claim 1 , wherein the corrected motion vector is generated based on the motion vector and motion vector difference information. According to claim 8,
When the first mode is a mode in which the geometric division mode and the merge mode using the motion vector difference are combined, the step of determining a motion vector from the merge candidate list includes:
Determining a motion vector for each of the two divided regions in the merge candidate list;
When the first mode is a mode in which the geometric division mode and the merge mode using the motion vector difference are combined, generating a prediction block of the current block includes:
generating an inter prediction block for each of the two divided regions using the corrected motion vector; and
generating a prediction block of the current block by combining or weighted averaging inter prediction blocks for each of the two divided regions;
The video encoding method of claim 1 , wherein the corrected motion vector is generated based on a motion vector for each of the two divided regions and motion vector difference information. According to claim 8,
When the first mode is a mode in which the CIIP mode, the geometric partitioning mode, and the merge mode using the motion vector difference are combined, the step of determining a motion vector from the merge candidate list includes:
Determining a motion vector for each of the two divided regions in the merge candidate list;
When the first mode is a mode in which the CIIP mode, the geometric partitioning mode, and the merge mode using the motion vector difference are combined, generating a prediction block of the current block,
generating a final inter-prediction block for the current block based on the two divided regions and the corrected motion vectors for each of the divided two regions;
generating an intra prediction block for the current block based on at least one reference pixel adjacent to the current block; and
generating a prediction block of the current block by weighting averaging the final inter prediction block and the intra prediction block;
The video encoding method of claim 1 , wherein the corrected motion vector is generated based on a motion vector for each of the two divided regions and motion vector difference information. According to claim 13,
Generating a final inter prediction block for the current block includes:
generating an inter-prediction block for each of the two divided regions using a motion vector corrected for each of the two divided regions; and
and generating a final inter-prediction block for the current block by combining or weighting-averaging inter-prediction blocks for each of the two divided regions. A computer-readable recording medium storing a bitstream generated by a video encoding method, the video encoding method comprising:
determining a first mode based on at least one of a CIIP mode, a geometric segmentation mode, and a merge mode using motion vector difference;
determining a motion vector from a merge candidate list; and
and generating a prediction block of a current block based on the first mode and the motion vector.

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