KR20200137326A - A method and an apparatus for processing a video signal using current picture referencing - Google Patents

Abstract

The present invention relates to a method and device for processing a video signal and, more specifically, to a method and device for processing a video signal to encode or decode a video signal. According to one embodiment of the present invention, a method for decoding an image includes the step of performing intra prediction or out-of-screen prediction.

Description

Video signal processing method and apparatus using current picture reference {A METHOD AND AN APPARATUS FOR PROCESSING A VIDEO SIGNAL USING CURRENT PICTURE REFERENCING}

The present invention relates to a video signal processing method and apparatus, and more particularly, to a video signal processing method and apparatus for encoding or decoding a video signal.

Compression coding refers to a series of signal processing techniques for transmitting digitized information through a communication line or storing it in a format suitable for a storage medium. Targets for compression encoding include audio, video, and text, and in particular, a technique for performing compression encoding on an image is referred to as video compression. Compression coding of a video signal is performed by removing redundant information in consideration of spatial correlation, temporal correlation, and probabilistic correlation. However, due to the recent development of various media and data transmission media, a more efficient method and apparatus for processing a video signal is required.

The present invention has an object to increase the coding efficiency of a video signal.

In order to solve the above problems, an image decoding method according to an embodiment of the present invention includes the step of predicting in-screen or out-of-screen.

According to an embodiment of the present invention, coding efficiency of a video signal may be improved.

1 is a schematic block diagram of a video signal encoding apparatus according to an embodiment of the present invention.
2 is a schematic block diagram of a video signal decoding apparatus according to an embodiment of the present invention.
3 shows an embodiment in which a coding tree unit is divided into coding units within a picture.
4 shows an embodiment of a method for signaling division of a quad tree and a multi-type tree.
5 illustrates an embodiment of reference samples used for prediction of a current block in an intra prediction mode.
6 shows an embodiment of prediction modes used for intra prediction.
7 is a diagram showing inter prediction according to an embodiment of the present invention.
8 is a diagram illustrating a motion vector signaling method according to an embodiment of the present invention.
9 is a diagram showing a motion vector difference syntax according to an embodiment of the present invention.
10 is a diagram showing adaptive motion vector resolution signaling according to an embodiment of the present invention.
11 is a diagram showing syntax related to inter prediction according to an embodiment of the present invention.
12 is a diagram showing a spatial neighboring location according to an embodiment of the present invention.
13 is a diagram showing current picture referencing according to an embodiment of the present invention.
14 is a diagram illustrating a method for referencing a spatial neighboring candidate according to an embodiment of the present invention.
15 is a diagram showing a block position and a motion candidate list configuration according to an embodiment of the present invention.
16 is a diagram showing a block position and a motion candidate list configuration according to an embodiment of the present invention.
17 is a diagram showing the use of a spatial neighboring candidate according to an embodiment of the present invention.
18 is a diagram showing a motion vector according to an embodiment of the present invention.
19 is a diagram showing a motion vector difference syntax according to an embodiment of the present invention.
20 is a diagram showing a motion vector according to an embodiment of the present invention.
21 is a diagram showing a motion vector difference syntax according to an embodiment of the present invention.
22 is a diagram showing a motion vector difference syntax according to an embodiment of the present invention.
23 is a diagram showing a block and a size according to an embodiment of the present invention.
24 is a diagram showing the configuration of a merge candidate list according to an embodiment of the present invention.
25 is a diagram showing a block location and syntax according to an embodiment of the present invention.
26 is a view showing resetting a space for storing HMVP history according to an embodiment of the present invention.
27 is a diagram showing a coding unit syntax according to an embodiment of the present invention.
28 is a diagram illustrating prediction mode signaling according to an embodiment of the present invention.
29 is a diagram illustrating prediction mode signaling according to an embodiment of the present invention.
30 is a diagram illustrating prediction mode signaling according to an embodiment of the present invention.
31 is a diagram showing a coding unit syntax according to an embodiment of the present invention.
32 is a diagram illustrating prediction mode signaling according to an embodiment of the present invention.
33 is a diagram illustrating a coding unit syntax according to an embodiment of the present invention.
34 is a diagram showing a coding unit syntax according to an embodiment of the present invention.
35 is a diagram illustrating intra prediction mode derivation of a chroma component according to an embodiment of the present invention.
36 is a diagram illustrating intra prediction mode derivation of a chroma component according to an embodiment of the present invention.
37 is a diagram showing a coding unit syntax according to an embodiment of the present invention.
38 is a diagram showing a syntax structure according to an embodiment of the present invention.
39 is a diagram illustrating a signaling value infer method according to an embodiment of the present invention.
40 is a diagram illustrating a signaling value infer method according to an embodiment of the present invention.
41 is a diagram illustrating an inter_pred_idc value and binarization according to an embodiment of the present invention.
42 is a diagram illustrating an inter_pred_idc value and binarization according to an embodiment of the present invention.
43 is a diagram illustrating an inter_pred_idc value and binarization according to an embodiment of the present invention.
44 is a diagram showing a coding unit syntax structure according to an embodiment of the present invention.
45 is a diagram illustrating skip mode and prediction mode signaling according to an embodiment of the present invention.
46 is a diagram showing a coding unit syntax structure according to an embodiment of the present invention.
47 is a diagram showing a coding unit syntax structure according to an embodiment of the present invention.
48 is a diagram showing a coding unit syntax structure according to an embodiment of the present invention.

The terms used in the present specification have been selected as currently widely used general terms as possible while considering the functions of the present invention, but this may vary according to the intention, custom, or the emergence of new technologies of the skilled person in the art. In addition, in certain cases, there are terms arbitrarily selected by the applicant, and in this case, the meaning will be described in the description of the corresponding invention. Therefore, it should be noted that the terms used in the present specification should be interpreted based on the actual meaning of the term and the entire contents of the present specification, not a simple name of the term.

In the present specification, some terms may be interpreted as follows. Coding can be interpreted as encoding or decoding in some cases. In this specification, an apparatus for generating a video signal bitstream by performing encoding (encoding) of a video signal is referred to as an encoding apparatus or an encoder, and an apparatus for restoring a video signal by performing decoding (decoding) of a video signal bitstream is decoding It is referred to as a device or decoder. In addition, in this specification, a video signal processing apparatus is used as a term for a concept including both an encoder and a decoder. Information is a term that includes all values, parameters, coefficients, elements, etc., and the meaning may be interpreted differently in some cases, so the present invention is not limited thereto. The'unit' is used to refer to a basic unit of image processing or a specific position of a picture, and refers to an image area including both a luma component and a chroma component. In addition, the'block' refers to an image region including a specific component among the luma component and the chroma components (ie, Cb and Cr). However, depending on the embodiment, terms such as'unit','block','partition', and'area' may be used interchangeably. In addition, in this specification, the unit may be used as a concept including all of a coding unit, a prediction unit, and a transform unit. A picture refers to a field or a frame, and the terms may be used interchangeably according to embodiments.

1 is a schematic block diagram of a video signal encoding apparatus according to an embodiment of the present invention. Referring to FIG. 1, the encoding apparatus 100 of the present invention includes a transform unit 110, a quantization unit 115, an inverse quantization unit 120, an inverse transform unit 125, a filtering unit 130, and a prediction unit 150. ) And an entropy coding unit 160.

The transform unit 110 converts a residual signal that is a difference between an input video signal and a prediction signal generated by the prediction unit 150 to obtain a transform coefficient value. For example, Discrete Cosine Transform (DCT), Discrete Sine Transform (DST), or Wavelet Transform may be used. Discrete cosine transform and discrete sine transform are transformed by dividing the input picture signal into a block form. In transformation, coding efficiency may vary depending on the distribution and characteristics of values in the transformation region. The quantization unit 115 quantizes a transform coefficient value output from the transform unit 110.

In order to improve coding efficiency, the picture signal is not coded as it is, but a reconstructed picture by predicting a picture using a region already coded through the prediction unit 150 and adding a residual value between the original picture and the predicted picture to the predicted picture. The method of obtaining is used. In order to prevent mismatches from occurring in the encoder and decoder, information available in the decoder must be used when performing prediction in the encoder. To this end, the encoder performs a process of reconstructing the encoded current block. The inverse quantization unit 120 inverse quantizes the transform coefficient value, and the inverse transform unit 125 restores the residual value by using the inverse quantization transform coefficient value. Meanwhile, the filtering unit 130 performs a filtering operation to improve the quality and encoding efficiency of the reconstructed picture. For example, a deblocking filter, a sample adaptive offset (SAO), and an adaptive loop filter may be included. The filtered picture is output or stored in a decoded picture buffer (DPB) 156 to be used as a reference picture.

The prediction unit 150 includes an intra prediction unit 152 and an inter prediction unit 154. The intra prediction unit 152 performs intra prediction within the current picture, and the inter prediction unit 154 predicts the current picture using a reference picture stored in the decoded picture buffer 156. Perform. The intra prediction unit 152 performs intra prediction from reconstructed samples in the current picture, and transmits intra encoding information to the entropy coding unit 160. The intra encoding information may include at least one of an intra prediction mode, a Most Probable Mode (MPM) flag, and an MPM index. The inter prediction unit 154 may include a motion estimation unit 154a and a motion compensation unit 154b. The motion estimation unit 154a obtains a motion vector value of the current region by referring to a specific region of the reconstructed reference picture. The motion estimation unit 154a transfers motion information (reference picture index, motion vector information, etc.) for the reference region to the entropy coding unit 160. The motion compensation unit 154b performs motion compensation using the motion vector value transmitted from the motion estimation unit 154a. The inter prediction unit 154 transmits inter encoding information including motion information on the reference region to the entropy coding unit 160.

When the above picture prediction is performed, the transform unit 110 obtains a transform coefficient value by transforming a residual value between the original picture and the predicted picture. In this case, the transformation may be performed in units of a specific block within the picture, and the size of the specific block may vary within a preset range. The quantization unit 115 quantizes the transform coefficient values generated by the transform unit 110 and transmits the quantization to the entropy coding unit 160.

The entropy coding unit 160 entropy-codes quantized transform coefficients, intra-encoding information, and inter-encoding information to generate a video signal bitstream. In the entropy coding unit 160, a variable length coding (VLC) method and an arithmetic coding method may be used. The variable length coding (VLC) method converts input symbols into consecutive codewords, and the length of the codeword may be variable. For example, frequently occurring symbols are expressed as short codewords, and infrequently occurring symbols are expressed as long codewords. As a variable length coding scheme, a context-based adaptive variable length coding (CAVLC) scheme may be used. Arithmetic coding converts consecutive data symbols into one prime number, and arithmetic coding can obtain an optimal prime bit necessary to represent each symbol. Context-based Adaptive Binary Arithmetic Code (CABAC) may be used as arithmetic coding.

The generated bitstream is encapsulated in a basic unit of a Network Abstraction Layer (NAL) unit. The NAL unit includes a coded integer number of coding tree units. In order to decode a bitstream in a video decoder, the bitstream must first be separated into NAL units, and then each separated NAL unit must be decoded. Meanwhile, information necessary for decoding a video signal bitstream is a high-level set such as a picture parameter set (PPS), a sequence parameter set (SPS), and a video parameter set (VPS). It may be transmitted through RBSP (Raw Byte Sequence Payload).

Meanwhile, the block diagram of FIG. 1 shows the encoding apparatus 100 according to an embodiment of the present invention, and separately displayed blocks are shown by logically distinguishing elements of the encoding apparatus 100. Accordingly, the elements of the encoding apparatus 100 described above may be mounted as one chip or as a plurality of chips according to the design of the device. According to an embodiment, the operation of each element of the encoding apparatus 100 described above may be performed by a processor (not shown).

2 is a schematic block diagram of a video signal decoding apparatus 200 according to an embodiment of the present invention. Referring to FIG. 2, the decoding apparatus 200 of the present invention includes an entropy decoding unit 210, an inverse quantization unit 220, an inverse transform unit 225, a filtering unit 230, and a prediction unit 250.

The entropy decoding unit 210 entropy-decodes the video signal bitstream and extracts transform coefficients, intra-encoding information, and inter-encoding information for each region. The inverse quantization unit 220 inverse quantizes the entropy-decoded transform coefficient, and the inverse transform unit 225 restores a residual value by using the inverse quantization transform coefficient. The video signal processing apparatus 200 restores the original pixel value by summing the residual value obtained by the inverse transform unit 225 with the predicted value obtained by the prediction unit 250.

Meanwhile, the filtering unit 230 improves image quality by filtering a picture. This may include a deblocking filter for reducing block distortion and/or an adaptive loop filter for removing distortion of an entire picture. The filtered picture is output or stored in the decoded picture buffer (DPB) 256 to be used as a reference picture for the next picture.

The prediction unit 250 includes an intra prediction unit 252 and an inter prediction unit 254. The prediction unit 250 generates a prediction picture by using an encoding type decoded by the entropy decoding unit 210 described above, a transform coefficient for each region, and intra/inter encoding information. In order to restore a current block on which decoding is performed, a current picture including the current block or a decoded area of other pictures may be used. An intra picture or an I picture (or tile/slice) using only the current picture for restoration, that is, performing only intra prediction (or tile/slice), a picture capable of performing both intra prediction and inter prediction (or, Tile/slice) is called an inter picture (or tile/slice). In order to predict the sample values of each block among inter-pictures (or tiles/slices), a picture (or tile/slice) using at most one motion vector and a reference picture index is a predictive picture or a P picture (or , Tile/slice), and a picture (or tile/slice) using up to two motion vectors and a reference picture index is referred to as a bi-predictive picture or a B picture (or tile/slice). In other words, a P picture (or tile/slice) uses at most one set of motion information to predict each block, and a B picture (or tile/slice) uses at most two motion information to predict each block. Use a set. Here, the motion information set includes one or more motion vectors and one reference picture index.

The intra prediction unit 252 generates a prediction block using intra-encoding information and reconstructed samples in the current picture. As described above, the intra encoding information may include at least one of an intra prediction mode, a Most Probable Mode (MPM) flag, and an MPM index. The intra prediction unit 252 predicts pixel values of the current block by using reconstructed pixels located on the left and/or above of the current block as reference pixels. According to an embodiment, the reference pixels may be pixels adjacent to the left boundary of the current block and/or pixels adjacent to the upper boundary. According to another embodiment, the reference pixels may be adjacent pixels within a preset distance from the left boundary of the current block among pixels of the neighboring block of the current block and/or pixels adjacent within a preset distance from the upper boundary of the current block. At this time, the neighboring block of the current block is a left (L) block, an upper (A) block, a lower left (BL) block, an upper right (AR) block, or an upper left (Above Left) block. AL) may include at least one of the blocks.

The inter prediction unit 254 generates a prediction block using a reference picture and inter encoding information stored in the decoded picture buffer 256. The inter encoding information may include motion information (reference picture index, motion vector information, etc.) of the current block for the reference block. Inter prediction may include L0 prediction, L1 prediction, and Bi-prediction. L0 prediction means prediction using one reference picture included in the L0 picture list, and L1 prediction means prediction using one reference picture included in the L1 picture list. For this, a set of motion information (eg, a motion vector and a reference picture index) may be required. In the bi-prediction scheme, up to two reference regions may be used, and the two reference regions may exist in the same reference picture or may exist in different pictures. That is, in the bi-prediction method, up to two sets of motion information (for example, a motion vector and a reference picture index) may be used, and the two motion vectors may correspond to the same reference picture index or to different reference picture indexes. May correspond. In this case, the reference pictures may be displayed (or output) temporally before or after the current picture.

The inter prediction unit 254 may obtain a reference block of the current block using a motion vector and a reference picture index. The reference block exists in a reference picture corresponding to a reference picture index. Also, a pixel value of a block specified by a motion vector or an interpolated value thereof may be used as a predictor of the current block. For motion prediction with pixel accuracy in sub-pel units, for example, an 8-tap interpolation filter for a luma signal and a 4-tap interpolation filter for a chroma signal may be used. However, the interpolation filter for motion prediction in units of subpels is not limited thereto. In this way, the inter prediction unit 254 performs motion compensation for predicting a texture of a current unit from a previously restored picture using motion information.

A reconstructed video picture is generated by adding a prediction value output from the intra prediction unit 252 or the inter prediction unit 254 and a residual value output from the inverse transform unit 225. That is, the video signal decoding apparatus 200 reconstructs the current block by using the prediction block generated by the prediction unit 250 and the residual obtained from the inverse transform unit 225.

Meanwhile, the block diagram of FIG. 2 shows the decoding apparatus 200 according to an embodiment of the present invention, and separately displayed blocks are shown by logically distinguishing elements of the decoding apparatus 200. Therefore, the elements of the decoding apparatus 200 described above may be mounted as one chip or as a plurality of chips according to the design of the device. According to an embodiment, the operation of each element of the decoding apparatus 200 described above may be performed by a processor (not shown).

3 shows an embodiment in which a coding tree unit (CTU) is divided into coding units (CUs) in a picture. In the process of coding a video signal, a picture may be divided into a sequence of coding tree units (CTUs). The coding tree unit is composed of an NXN block of luma samples and two blocks of chroma samples corresponding thereto. The coding tree unit may be divided into a plurality of coding units. The coding unit refers to a basic unit for processing a picture in the above-described video signal processing, that is, intra/inter prediction, transformation, quantization, and/or entropy coding. The size and shape of a coding unit in one picture may not be constant. The coding unit may have a square or rectangular shape. The rectangular coding unit (or rectangular block) includes a vertical coding unit (or vertical block) and a horizontal coding unit (or horizontal block). In this specification, a vertical block is a block having a height greater than a width, and a horizontal block is a block having a width greater than the height. In addition, in the present specification, a non-square block may refer to a rectangular block, but the present invention is not limited thereto.

Referring to FIG. 3, a coding tree unit is first divided into a quad tree (QT) structure. That is, in a quad tree structure, one node having a size of 2NX2N may be divided into four nodes having a size of NXN. In this specification, the quad tree may also be referred to as a quaternary tree. Quad-tree partitioning can be performed recursively, and not all nodes need to be partitioned to the same depth.

Meanwhile, the leaf node of the quad tree described above may be further divided into a multi-type tree (MTT) structure. According to an embodiment of the present invention, in a multi-type tree structure, one node may be divided into a horizontal or vertically divided binary (binary) or ternary (ternary) tree structure. That is, in the multi-type tree structure, there are four division structures: vertical binary division, horizontal binary division, vertical ternary division, and horizontal ternary division. According to an embodiment of the present invention, both widths and heights of nodes in each tree structure may have a power of 2. For example, in a binary tree (Binary Tree, BT) structure, a node having a size of 2NX2N may be divided into two NX2N nodes by vertical binary division, and divided into two 2NXN nodes by horizontal binary division. In addition, in a ternary tree (TT) structure, a node of 2NX2N size is divided into nodes of (N/2)X2N, NX2N and (N/2)X2N by vertical ternary division, and horizontal binary division It can be divided into 2NX(N/2), 2NXN, and 2NX(N/2) nodes by. This multi-type tree division can be performed recursively.

Leaf nodes of a multi-type tree can be coding units. If the coding unit is not too large for the maximum transform length, the coding unit is used as a unit of prediction and transform without further division. Meanwhile, in the above-described quad tree and multi-type tree, at least one of the following parameters may be defined in advance or transmitted through RBSP of a higher level set such as PPS, SPS, and VPS. 1) CTU size: the size of the root node of the quad tree, 2) the minimum QT size (MinQtSize): the minimum QT leaf node size allowed, 3) the maximum BT size (MaxBtSize): the maximum BT root node size allowed, 4) Maximum TT size (MaxTtSize): Maximum allowed TT root node size, 5) Maximum MTT depth (MaxMttDepth): Maximum allowable depth of MTT split from leaf node of QT, 6) Minimum BT size (MinBtSize): Allowed Minimum BT leaf node size, 7) Minimum TT size (MinTtSize): Minimum allowed TT leaf node size.

4 shows an embodiment of a method for signaling division of a quad tree and a multi-type tree. Pre-set flags may be used to signal the division of the quad tree and multi-type tree described above. 4, a flag'qt_split_flag' indicating whether to divide a quad tree node, a flag'mtt_split_flag' indicating whether to divide a multi-type tree node, and a flag'mtt_split_vertical_flag' indicating a splitting direction of a multi-type tree node. 'Or at least one of a flag'mtt_split_binary_flag' indicating the split shape of the multi-type tree node may be used.

According to an embodiment of the present invention, the coding tree unit is a root node of a quad tree, and may be divided first into a quad tree structure. In the quad tree structure, a'qt_split_flag' is signaled for each node'QT_node'. If the value of'qt_split_flag' is 1, the node is divided into 4 square nodes, and if the value of'qt_split_flag' is 0, the node becomes'QT_leaf_node' of the quad tree leaf node.

Each quad tree leaf node'QT_leaf_node' may be further divided into a multi-type tree structure. In the multi-type tree structure,'mtt_split_flag' is signaled for each node'MTT_node'. When the value of'mtt_split_flag' is 1, the node is divided into a plurality of rectangular nodes. When the value of'mtt_split_flag' is 0, the node becomes'MTT_leaf_node' of the multi-type tree. When the multi-type tree node'MTT_node' is divided into a plurality of rectangular nodes (i.e., when the value of'mtt_split_flag' is 1),'mtt_split_vertical_flag' and'mtt_split_binary_flag' for node'MTT_node' will be additionally signaled. I can. When the value of'mtt_split_vertical_flag' is 1, vertical division of the node'MTT_node' is indicated, and when the value of'mtt_split_vertical_flag' is 0, horizontal division of the node'MTT_node' is indicated. In addition, when the value of'mtt_split_binary_flag' is 1, the node'MTT_node' is divided into two rectangular nodes, and when the value of'mtt_split_binary_flag' is 0, the node'MTT_node' is divided into 3 rectangular nodes.

5 and 6 more specifically illustrate an intra prediction method according to an embodiment of the present invention. As described above, the intra prediction unit predicts pixel values of the current block by using reconstructed pixels located on the left and/or above of the current block as reference pixels.

First, FIG. 5 shows an embodiment of reference samples used for prediction of a current block in an intra prediction mode. According to an embodiment, the reference pixels may be pixels adjacent to the left boundary of the current block and/or pixels adjacent to the upper boundary. As shown in FIG. 5, when the size of the current block is WXH and pixels of a single reference line adjacent to the current block are used for intra prediction, a maximum of 2W+2H+1 located on the left and/or upper side of the current block Reference pixels can be set using n adjacent pixels. Meanwhile, according to an additional embodiment of the present invention, pixels of multiple reference lines may be used for intra prediction of a current block. The multiple reference line may consist of n lines located within a preset range from the current block. According to an embodiment, when pixels of multiple reference lines are used for intra prediction, separate index information indicating lines to be set as reference pixels may be signaled. When at least some adjacent pixels to be used as reference pixels have not yet been reconstructed, the intra prediction unit may obtain a reference pixel by performing a reference sample padding process according to a preset rule. Also, the intra prediction unit may perform a reference sample filtering process to reduce an error in intra prediction. That is, reference pixels may be obtained by filtering adjacent pixels and/or pixels obtained by the reference sample padding process. The intra prediction unit predicts the pixels of the current block by using the obtained reference pixels.

Next, FIG. 6 shows an embodiment of prediction modes used for intra prediction. For intra prediction, intra prediction mode information indicating an intra prediction direction may be signaled. The intra prediction mode information indicates any one of a plurality of intra prediction modes constituting the intra prediction mode set. When the current block is an intra prediction block, the decoder receives intra prediction mode information of the current block from the bitstream. The intra prediction unit of the decoder performs intra prediction on the current block based on the extracted intra prediction mode information.

According to an embodiment of the present invention, the intra prediction mode set may include all intra prediction modes (eg, a total of 67 intra prediction modes) used for intra prediction. More specifically, the intra prediction mode set may include a planar mode, a DC mode, and a plurality (eg, 65) angular modes (ie, directional modes). Each intra prediction mode may be indicated through a preset index (ie, an intra prediction mode index). For example, as shown in FIG. 6, intra prediction mode index 0 indicates a planar mode, and intra prediction mode index 1 indicates a DC mode. In addition, intra prediction mode indexes 2 to 66 may indicate different angular modes, respectively. The angle modes indicate different angles within a preset angle range, respectively. For example, the angle mode may indicate an angle within an angle range between 45 degrees and -135 degrees in a clockwise direction (ie, a first angle range). The angular mode may be defined based on the 12 o'clock direction. At this time, intra prediction mode index 2 indicates a horizontal diagonal (HDIA) mode, intra prediction mode index 18 indicates a horizontal (HOR) mode, and intra prediction mode index 34 indicates a diagonal (Diagonal, DIA) mode. A mode is indicated, an intra prediction mode index 50 indicates a vertical (VER) mode, and an intra prediction mode index 66 indicates a vertical diagonal (VDIA) mode.

Meanwhile, the preset angle range may be set differently according to the shape of the current block. For example, when the current block is a rectangular block, a wide-angle mode indicating an angle exceeding 45 degrees or less than -135 degrees clockwise may be additionally used. When the current block is a horizontal block, the angle mode may indicate an angle within an angle range (that is, a second angle range) between (45+offset1) degrees and (-135+offset1) degrees in a clockwise direction. In this case, angle modes 67 to 76 outside the first angle range may be additionally used. In addition, when the current block is a vertical block, the angle mode may indicate an angle within an angle range (ie, a third angle range) between (45-offset2) degrees and (-135-offset2) degrees in a clockwise direction. . In this case, angle modes -10 to -1 outside the first angle range may be additionally used. According to an embodiment of the present invention, values of offset1 and offset2 may be determined differently according to a ratio between the width and height of the rectangular block. Also, offset1 and offset2 may be positive numbers.

According to a further embodiment of the present invention, a plurality of angular modes constituting the intra prediction mode set may include a basic angular mode and an extended angular mode. In this case, the extended angle mode may be determined based on the basic angle mode.

According to an embodiment, the basic angle mode is a mode corresponding to an angle used in intra prediction of an existing HEVC (High Efficiency Video Coding) standard, and the extended angle mode corresponds to an angle newly added in intra prediction of the next generation video codec standard. It can be a mode to do. More specifically, the basic angular mode is an intra prediction mode {2, 4, 6, ... , 66}, and the extended angle mode is an intra prediction mode {3, 5, 7, ... , 65} may be an angle mode corresponding to any one of. That is, the extended angle mode may be an angle mode between basic angle modes within the first angle range. Accordingly, the angle indicated by the extended angle mode may be determined based on the angle indicated by the basic angle mode.

According to another embodiment, the basic angle mode is a mode corresponding to an angle within a preset first angle range, and the extended angle mode may be a wide angle mode outside the first angle range. That is, the basic angular mode is the intra prediction mode {2, 3, 4,… , 66}, and the extended angle mode is an intra prediction mode {-10, -9, ... , -1} and {67, 68,… , 76} may be an angular mode corresponding to any one of. The angle indicated by the extended angle mode may be determined as an angle opposite to the angle indicated by the corresponding basic angle mode. Accordingly, the angle indicated by the extended angle mode may be determined based on the angle indicated by the basic angle mode. Meanwhile, the number of expansion angle modes is not limited thereto, and additional expansion angles may be defined according to the size and/or shape of the current block. For example, the extended angle mode is the intra prediction mode {-14, -13,… , -1} and {67, 68,… , 80} may be defined as an angle mode corresponding to any one of. Meanwhile, the total number of intra prediction modes included in the intra prediction mode set may vary according to the configuration of the above-described basic angle mode and extended angle mode.

In the above embodiments, the spacing between the extended angle modes may be set based on the spacing between the corresponding basic angle modes. For example, extended angle modes {3, 5, 7,… , 65} the spacing between the corresponding basic angular modes {2, 4, 6,… , 66} can be determined based on the interval. Also, the extended angle modes {-10, -9,… , -1} the spacing between the corresponding opposite basic angular modes {56, 57,… , 65}, determined based on the spacing between the extended angle modes {67, 68, ... , 76} the spacing between the corresponding opposite basic angular modes {3, 4,… , 12} may be determined based on the interval. The angular interval between the extended angular modes may be set to be the same as the angular interval between the corresponding basic angular modes. In addition, the number of extended angle modes in the intra prediction mode set may be set to be less than or equal to the number of basic angle modes.

According to an embodiment of the present invention, the extended angle mode may be signaled based on the basic angle mode. For example, the wide-angle mode (ie, the extended angle mode) may replace at least one angle mode (ie, the basic angle mode) within the first angle range. The replaced default angle mode may be an angle mode corresponding to the opposite side of the wide angle mode. That is, the replaced basic angle mode is an angle mode that corresponds to an angle in a direction opposite to the angle indicated by the wide-angle mode or to an angle that differs by a preset offset index from the angle in the opposite direction. According to an embodiment of the present invention, the preset offset index is 1. The intra prediction mode index corresponding to the replaced basic angular mode may be remapped to the wide-angle mode to signal the corresponding wide-angle mode. For example, wide-angle mode {-10, -9,… , -1} is the intra prediction mode index {57, 58, ... , 66}, each can be signaled by the wide-angle mode {67, 68, ... , 76} is an intra prediction mode index {2, 3, ... , 11}, respectively. In this way, the intra prediction mode index for the basic angular mode signals the extended angular mode, so that even if the configuration of the angular modes used for intra prediction of each block is different, the intra prediction mode indexes of the same set are Can be used. Accordingly, signaling overhead due to changes in the intra prediction mode configuration can be minimized.

Meanwhile, whether to use the extended angle mode may be determined based on at least one of the shape and size of the current block. According to an embodiment, when the size of the current block is larger than a preset size, the extended angle mode is used for intra prediction of the current block, otherwise, only the basic angle mode may be used for intra prediction of the current block. According to another embodiment, when the current block is a non-square block, the extended angle mode is used for intra prediction of the current block, and when the current block is a square block, only the basic angle mode may be used for intra prediction of the current block.

The intra prediction unit determines reference pixels and/or interpolated reference pixels to be used for intra prediction of the current block, based on the intra prediction mode information of the current block. When the intra prediction mode index indicates a specific angular mode, a reference pixel corresponding to the specific angle from the current pixel of the current block or an interpolated reference pixel is used for prediction of the current pixel. Accordingly, different sets of reference pixels and/or interpolated reference pixels may be used for intra prediction according to the intra prediction mode. After intra prediction of the current block is performed using reference pixels and intra prediction mode information, the decoder restores pixel values of the current block by adding the residual signal of the current block obtained from the inverse transform unit with the intra prediction value of the current block.

7 is a diagram showing inter prediction according to an embodiment of the present invention.

As described above, when encoding or decoding the current picture or block, prediction can be made from another picture or block. In other words, it is possible to encode and decode based on similarity with other pictures or blocks. A portion similar to another picture or block may be encoded and decoded by signaling omitted in the current picture or block, which will be described further below. It is possible to make predictions in blocks.

Referring to FIG. 7, there is a reference picture (reference picture) on the left and a current picture (current picture) on the right, and a current picture or a part of the current picture can be predicted using similarity with the reference picture or a part of the reference picture. have. Assuming that a rectangle indicated by a solid line in the current picture of FIG. 7 is a block currently encoding and decoding, the current block may be predicted from a rectangle indicated by a dotted line of the reference picture. At this time, information indicating a block (reference block) to be referred to by the current block may exist, which may be directly signaled or may be generated by a certain promise to reduce signaling overhead. The information indicating the block to be referred to by the current block may include a motion vector. This may be a vector indicating a relative position in the picture between the current block and the reference block. Referring to FIG. 7, there is a portion indicated by a dotted line of a reference picture, and a vector indicating how a current block can move to a block to be referred to of a reference picture may be a motion vector. That is, the block that appears when the current block is moved according to the motion vector may be a portion indicated by a dotted line in the current picture of FIG. 7, and the portion indicated by the dotted line may have a position in the picture equal to the reference block position of the reference picture.

In addition, information indicating a block to be referred to by the current block may include information indicating a reference picture. Information indicating the reference picture may include a reference picture list and a reference picture index. The reference picture list is a list representing reference pictures, and it is possible to use a reference block in a reference picture included in the reference picture list. That is, it is possible to predict the current block from the reference picture included in the reference picture list. Also, the reference picture index may be an index for indicating a reference picture to be used.

8 is a diagram illustrating a motion vector signaling method according to an embodiment of the present invention.

According to an embodiment of the present invention, a motion vector (MV) may be generated based on a motion vector predictor (MVP). For example, the motion vector predictor can be a motion vector as shown below.

MV = MVP

As another example, the motion vector can be based on the motion vector difference (MVD) as follows. Motion vector difference (MVD) can be added to the motion vector predictor to represent the correct motion vector.

MV = MVP + MVD

In addition, in video coding, motion vector information determined by an encoder is transmitted to a decoder, and the decoder can generate a motion vector from the received motion vector information and determine a prediction block. For example, the motion vector information may include information on a motion vector predictor and a motion vector difference. In this case, a component of the motion vector information may vary depending on the mode. For example, in the merge mode, the motion vector information may include information on a motion vector predictor and may not include a motion vector difference. As another example, in the advanced motion vector prediction (AMVP) mode, the motion vector information may include information about a motion vector predictor and may include a motion vector difference.

In order to determine, transmit, and receive information on the motion vector predictor, the encoder and decoder can generate MVP candidates in the same way. For example, the encoder and the decoder can generate the same MVP candidate in the same order. In addition, the encoder transmits an index representing the MVP determined among the generated MVP candidates to the decoder, and the decoder can find out the MVP and MV determined based on the index.

The MVP candidate and MVP candidate generation method may include a spatial candidate and a temporal candidate. Spatial candidate may be a motion vector for a block at a certain position from the current block. For example, it may be a motion vector corresponding to a block or position adjacent to or not adjacent to the current block. The temporal candidate may be a motion vector corresponding to a block in a picture different from the current picture. Alternatively, the MVP candidate may include an affine motion vector, ATMVP, STMVP, a combination of motion vectors described above, an average vector of motion vectors described above, a zero motion vector, and the like.

In addition, information indicating the reference picture described above may also be transmitted from the encoder to the decoder. Also, motion vector scaling can be performed when a reference picture corresponding to an MVP candidate does not correspond to information indicating a reference picture. Motion vector scaling may be a calculation based on a picture order count (POC) of a current picture, a POC of a reference picture of a current block, a POC of a reference picture of an MVP candidate, and an MVP candidate.

9 is a diagram showing a motion vector difference syntax according to an embodiment of the present invention.

The motion vector difference can be coded by dividing the sign and absolute value of the motion vector difference. That is, the sign and absolute value of the motion vector difference may have different syntax. Also, the absolute value of the motion vector difference may be directly coded, but may be coded by including a flag indicating whether the absolute value is greater than N as shown in FIG. 9. If the absolute value is greater than N, the value of (absolute value-N) can be signaled together. In the example of FIG. 9, abs_mvd_greater0_flag may be transmitted, and this flag may be a flag indicating whether the absolute value is greater than 0. If abs_mvd_greater0_flag indicates that the absolute value is not greater than 0, it can be determined that the absolute value is 0. Also, if abs_mvd_greater0_flag is indicated when the absolute value is greater than 0, additional syntax may exist. For example, abs_mvd_greater1_flag may exist, and this flag may be a flag indicating whether the absolute value is greater than 1. If abs_mvd_greater1_flag is indicated that the absolute value is not greater than 1, it can be determined that the absolute value is 1. If abs_mvd_greater1_flag is indicated when the absolute value is greater than 1, additional syntax may exist. For example, abs_mvd_minus2 may exist, which may be a value of (absolute value-2). It is determined that the absolute value is greater than 1 (more than 2) through abs_mvd_greater0_flag and abs_mvd_greater1_flag described above, indicating (absolute value-2). When abs_mvd_minus2 is binarized to a variable length, this is for signaling with fewer bits. For example, there are variable length binarization methods such as Exp-Golomb, truncated unary, and truncated Rice. Also, mvd_sign_flag may be a flag indicating a sign of motion vector difference.

In this embodiment, the coding method was described through motion vector difference, but information other than motion vector difference is also divided about sign and absolute value, and the absolute value is a flag indicating whether the absolute value is greater than a certain value and the value of the absolute value. It is possible to code by subtracting.

In addition, [0] and [1] in FIG. 9 may represent component indexes. For example, it can represent x-component and y-component.

In addition, cpIdx in FIG. 9 may indicate a control point index. The control point index may be an index corresponding to the control motion vector index in affine motion prediction. Also, in a prediction method other than affine motion prediction, cpIdx can be used as a preset value such as 0, for example.

10 is a diagram showing adaptive motion vector resolution signaling according to an embodiment of the present invention.

According to an embodiment of the present invention, resolution representing a motion vector or a motion vector difference may vary. In other words, the resolution at which the motion vector or motion vector difference is coded may vary. For example, resolution can be expressed based on pixel(pel). For example, a motion vector or a motion vector difference may be signaled in units such as 1/4 (quarter), 1/2 (half), 1 (integer), 2, and 4 pixels. For example, if you want to represent 16, if you use 1/4, you code 64 (1/4 * 64 = 16), if you use 1 unit, you code 16 (1 * 16 = 16), and if you use 4 units, it is 4 Can code (4 *. 4 = 16). That is, the value can be determined as follows.

valueDetermined = resolution*valuePerResolution

Here, valueDetermined may be a value to be transferred, and in this embodiment, a motion vector or a motion vector difference. In addition, valuePerResolution may be a value expressed in units of valueDetermined in [/resolution].

At this time, if the value signaled by the motion vector or the motion vector difference is not divided by the resolution, an inaccurate value other than the motion vector or the motion vector difference with the best prediction performance may be transmitted through rounding. If high resolution is used, inaccuracy may be reduced, but many bits can be used because the coded value is large, and if low resolution is used, inaccuracy may be increased, but because the coded value is small, fewer bits can be used.

In addition, it is possible to set the resolution differently in units such as block, CU, or slice. Therefore, resolution can be adaptively applied to fit the unit.

The resolution can be signaled from the encoder to the decoder. At this time, the signaling for resolution may be the signaling binarized with the variable length described above. In this case, signaling overhead is reduced when signaling with the index corresponding to the smallest value (the value in front of it).

In one embodiment, the signaling index may be matched in order from high resolution (detail signaling) to low resolution.

10 shows signaling for three resolutions. In this case, the three signaling can be 0, 10, 11, and each of the three signaling can correspond to resolution 1, resolution 2, and resolution 3. Signaling overhead is small when signaling resolution 1 because 1 bit is required to signal resolution 1 and 2 bits are required to signal the remaining resolution. In the example of FIG. 10, resolution 1, resolution 2, and resolution 3 are 1/4, 1, and 4 pel, respectively.

In the following inventions, motion vector resolution may mean resolution of motion vector difference.

11 is a diagram showing syntax related to inter prediction according to an embodiment of the present invention.

According to an embodiment of the present invention, the inter prediction method may include a skip mode, a merge mode, and an inter mode. According to an embodiment, a residual signal may not be transmitted in the skip mode. Also, in skip mode, the same MV determination method as merge mode can be used. Whether to use the skip mode may be determined according to the skip flag. Referring to FIG. 11, whether to use the skip mode may be determined according to a cu_skip_flag value.

According to an embodiment, the motion vector difference may not be used in the merge mode. The motion vector can be determined based on the motion candidate index. Whether to use the merge mode may be determined according to the merge flag. Referring to FIG. 11, whether to use a merge mode may be determined according to a merge_flag value. Also, it is possible to use merge mode when skip mode is not used.

It is possible to selectively use one or more candidate list types in skip mode or merge mode. For example, it is possible to use a merge candidate or a subblock merge candidate. In addition, the merge candidate may include a spatial neighboring candidate and a temporal candidate. Also, the merge candidate may include a candidate that uses a motion vector for the entire current block (CU). That is, the motion vector of each subblock belonging to the current block may contain the same candidate. In addition, the subblock merge candidate may include subblock-based temporal MV, affine merge candidate, etc. In addition, the subblock merge candidate may include a candidate capable of using a different motion vector for each subblock of the current block (CU). Affine merge candidate may be a method created by determining a control point motion vector of affine motion prediction without using a motion vector difference. In addition, the subblock merge candidate may include methods of determining a motion vector in units of subblocks in the current block. For example, the subblock merge candidate may include planar MV, regression based MV, STMVP, etc. in addition to the subblock-based temporal MV and affine merge candidate mentioned above.

According to an embodiment, a motion vector difference may be used in inter mode. A motion vector predictor may be determined based on a motion candidate index, and a motion vector may be determined based on the motion vector predictor and a motion vector difference. Whether to use the inter mode may be determined according to whether other modes are used. In another embodiment, whether to use the inter mode may be determined by a flag. FIG. 11 shows an example of using the inter mode when other modes such as skip mode and merge mode are not used.

Inter mode may include AMVP mode, affine inter mode, and the like. Inter mode may be a mode for determining a motion vector based on a motion vector predictor and a motion vector difference. Affine inter mode may be a method of using a motion vector difference when determining a control point motion vector of affine motion prediction.

Referring to FIG. 11, it is possible to determine whether to use a subblock merge candidate or a merge candidate after determining as a skip mode or a merge mode. For example, when a specific condition is satisfied, a merge_subblock_flag indicating whether to use a subblock merge candidate can be parsed. In addition, the specific condition may be a condition related to block size. For example, it can be conditions related to width, height, area, etc. You can also use them in combination. Referring to FIG. 11, for example, it may be a condition when the width and height of the current block (CU) are greater than or equal to a specific value. When parsing the merge_subblock_flag, the value can be inferred to 0. If merge_subblock_flag is 1, the subblock merge candidate may be used, and if it is 0, the merge candidate may be used. When using the subblock merge candidate, the candidate index merge_subblock_idx can be parsed, and when the merge candidate is used, the candidate index merge_idx can be parsed. In this case, if the maximum number of candidate list is 1, parsing may not be performed. If merge_subblock_idx or merge_idx is not parsed, it can be inferred to 0.

FIG. 11 shows a coding_unit function, and content related to intra prediction may be omitted, and FIG. 11 may indicate a case where inter prediction is determined.

12 is a diagram showing a spatial neighboring location according to an embodiment of the present invention.

As described above, when performing prediction, a location around the current block can be referenced. This may refer to motion information corresponding to a position around the current block. For example, when using the merge mode or AMVP mode, it is possible to set the MVP or the MV based on motion information corresponding to the position around the current block. The surrounding location may be preset. In addition, when there are a plurality of the surrounding locations, an order of referencing them may be preset. Also, the surrounding location may include a spatial neighbor and a temporal neighbor.

Referring to FIG. 12, positions corresponding to A0, A1, B0, B1, and B2 may be preset. Also, the location here can mean luma location. When the top-left position of the current block is (xCb, yCb), A0, A1, B0, B1, B2 are (xCb-1, yCb + cbHeight), (xCb-1, yCb + cbHeight-1), ( xCb + cbWidth, yCb-1), (xCb + cbWidth-1, yCb-1),, (xCb-1, yCb-1). At this time, cbWidth and cbHeight may be the width and height of the current block, respectively.

According to an embodiment of the present invention, a spatial neighbor may be referred to in the order of A1, B1, B0, A0, and B2 in merge mode. Also, a spatial candidate corresponding to a spatial neighbor location can be added to the candidate list. In addition, a temporal candidate can be added in addition to the spatial candidate, and this can be behind the spatial candidate. Also, a motion vector corresponding to a temporal candidate can be called a collocated motion vector.

Also, if the candidate list is not filled, a zero motion vector can be added to the candidate list. The zero motion vector may be a motion vector in which the motion vector points to the current block position.

Also, a history-based motion vector prediction candidate and a pairwise average candidate may be included in the merge candidate list. It is possible to place it behind the spatial candidate in the candidate list. The history-based motion vector prediction candidate may be stored motion information. In addition, the stored motion information may be motion information corresponding to a block decoded (encoded) before the current block. In addition, the pairwise average candidate may be a candidate generated based on candidates already added to the candidate list. For example, the pairwise average candidate may be an average of candidates already added to the candidate list.

The motion vector scaling process may be included in the process of adding to the candidate list by referring to locations around the current block described above. Motion vector scaling may be performed based on a picture order count (POC) of a reference picture of referenced motion information, a POC of a picture including a current block, a POC of a reference picture of a current block, and referenced motion information.

According to an embodiment of the present invention, a group may be set among preset spatial neighbor locations. In addition, it is possible to refer to a preset number of motion information among the groups. For example, a preset number of motion information among group 1 may be referred to, and a preset number of motion information may be referred to among group 2. For example, the preset number may be 1. Also, a reference order within a group may be preset. Also, the order of adding candidates between groups may be preset.

Referring to FIG. 12, it is possible that group 1 is A0 and A1, and group 2 is B0, B1, and B2. Also, a candidate can be created from motion information available in group 1, and a candidate can be created from motion information available in group 2. Also, candidates from group 1 can be added to the candidate list, and candidates from group 2 can be added to the candidate list in order. For example, it can be made as described in the candidate list in AMVP mode.

In addition, when the candidate list is not filled, it is possible to add a scaled candidate, a temporal candidate, and a zero motion vector.

13 is a diagram showing current picture referencing according to an embodiment of the present invention.

As described above, when predicting the current block, the block in the reference picture can be referenced. According to an embodiment of the present invention, it is possible that the reference picture is a picture including a current block, that is, a current picture. Therefore, when predicting the current block, it is possible to refer to the block of the current picture. This technique can be called current picture referencing (CPR).

According to an embodiment, when CPR is used, it is possible that the current picture is the only reference picture. In this case, it is possible to omit the signaling indicating the reference picture and infer.

According to an embodiment, when CPR is used, a motion vector indicating a reference block to be referred to by the current block may exist. According to an embodiment, when CPR is used, the position of the reference block may be limited. For example, the position of the reference block may be limited based on the current block position. For example, the position of the reference block may be limited inside the CTU containing the current block. Alternatively, the position of the reference block may be limited to a position that includes at least part of the CTU including the current block. Limiting the reference block location may be to reduce the memory burden.

According to an embodiment of the present invention, signaling indicating whether the current block uses CPR may exist. In an embodiment, such signaling may be signaling in a larger unit including the current block. For example, signaling at the slice or tile level is possible. In an embodiment, for example, when the reference picture referenced by the current block is the current picture, it is possible to use CPR. Alternatively, when the current picture is the only reference picture, it is possible to use CPR. In addition, it is possible to use CPR when the current block is a block that does not use intra prediction. That is, for example, when the reference picture corresponding to the current block is the current picture, it is possible to use CPR if intra prediction is not used. In an embodiment, it is possible to indicate that the current picture is the only reference picture with a variable called CurrPicIsOnlyRef. Alternatively, when CPR is used, the reference picture may be the current picture. Alternatively, the use of CPR may indicate that the reference picture is the current picture, and intra prediction is not used.

According to an embodiment of the present invention, when using CPR, it is possible to represent motion information using the merge mode, AMVP mode, and the like described above.

Also, when using CPR, it is possible to set the current slice or tile as P slice or P tile. Also, when CPR is used, the flag indicating that the dual tree is used can be set to a value indicating that the dual tree is used. The dual tree may mean that the tree corresponding to luma and the tree corresponding to chroma may be different.

Referring to FIG. 13, there may be a current block indicated by a solid line in a current picture. Also, a reference block indicated by a dotted line may exist in the current picture. At this time, motion information indicating the position of the reference block may exist. Referring to FIG. 13, what is indicated by an arrow may be motion information indicating a reference block position.

In addition, according to an embodiment of the present invention, when CPR is used, a candidate list configuration may be different. For example, when CPR is used, temporal candidates may not be included in the candidate list.

In addition, according to an embodiment of the present invention, when CPR is used, motion information referred to in the vicinity may not be scaled.

14 is a diagram illustrating a method for referencing a spatial neighboring candidate according to an embodiment of the present invention.

According to an embodiment of the present invention, when a current block uses CPR, a method of constructing a candidate list may be different from a case where CPR is not used. For example, when the current block uses CPR, the method of adding a spatial neighboring candidate may be different from the case where CPR is not used. For example, if the current block uses CPR, it may not refer to motion information of a position beyond the range in which the reference block of CPR can be located. Alternatively, when the current block uses CPR, motion information of a position beyond the range based on the range in which the reference block of CPR can be located may not be referred. The range in which the reference block of the CPR can be located may be a CTU range to which the current block belongs. Therefore, according to an embodiment of the present invention, motion information may not be referenced from a position beyond the current CTU. For example, if the current block is in contact with a boundary boundary in which a reference block can be located, a preset spatial neighbor position may be outside the range in which a reference block can be located. In particular, referring to the preset spatial neighbor location of FIG. 12, when the current block is in contact with the top boundary or the left boundary within the range in which the reference block can be located, a number of preset spatial neighbor locations are outside the range in which the reference block can be located. I can.

Referring to FIG. 14, a position of a reference block inside the CTU may be limited. According to an embodiment, motion information from a position outside the range in which the reference block can be located may not be referred. For example, when the current block is located in a boundary within a range that a reference block can have, a preset spatial neighbor location may be out of a range where the reference block can be located. In FIG. 14, a predetermined spatial neighbor around the current block is indicated by a small dotted rectangle. At this time, it may be determined that the location outside the CTU is not usable.

This is because the range of motion information that can be possessed is narrow so that the reference block of the current block or the reference block of the referenced position does not exceed the limited range when a reference block refers to a position beyond the range. to be. For example, in the case of FIG. 14, the reference block of the part marked as not available should not exceed the CTU to which it belongs. In addition, in order that the position indicated by the motion information of the part marked as not available does not exceed the range in which the reference block of the current block can be located, the y component of the motion information of the referenced part should be 0. If the current block is in contact with the left boundary, the x component of motion information of the referenced part outside the boundary must be 0. In addition, even in a situation where the x component or y component is 0 and the remaining components are not 0, only the sign of one component (e.g. minus) in the preset coding order is valid, or when the sign is other than the code, MVD is calculated. It can be more likely to make it bigger.

If the reference block is further described as being limited to the inside of the current CTU, since only the inside of the CTU is used as a reference block, there may be little correlation between the MVs. Also, if MVD correction is not possible, such as in merge mode, when MVs outside the CTU have both x and y components, the current block or the reference block of the neighboring block exceeds the CTU range. For example, if the current block is on the upper boundary of the CTU, if there is a y component of the upper block MV, the current block or neighboring blocks exceed the CTU range.

Since the entire slice becomes CPR, the surrounding block may also have used intra or CPR.

If there is a tile boundary (or there is a slice other than CPR), the surrounding may be inter, not CPR. In that case, the surrounding MV may point to a distant place and deviate from the CTU. Also, since the surrounding MV points to different pictures, there will be little correlation.

Therefore, according to an embodiment of the present invention, it is possible to refer to motion information only when a spatial neighbor location referred to by a current block using CPR uses CPR. Alternatively, if the spatial neighbor location referenced by the current block using CPR does not use CPR, it is possible not to refer to motion information therefrom.

According to another embodiment, motion information of a spatial neighbor location may be referenced by clipping into a range that a reference block corresponding to a current block may have.

As in the embodiment of FIG. 14, when reducing possible spatial neighbor locations, it is possible to reduce the total number of candidates. In this case, it is possible to reduce candidate index signaling. For example, a spatial neighboring candidate and a zero motion vector of a preset location can be added to the candidate list, or i) a spatial neighboring candidate of a preset location, ii) a limited number of HMVP candidates or pairwise average candidates, iii) a zero motion vector. In the case that it can be added to the candidate list, if possible spatial neighbor locations are reduced, the number of possible candidates can be reduced. In such a case, the number of bits can be reduced when the index is binarized by reducing the max value of the candidate index.

Or, when reducing the possible spatial neighbor location as in the embodiment of FIG. 14, when using a candidate that can be added after the spatial neighboring candidate by allowing a candidate that can be added after the spatial neighboring candidate to be added earlier in the candidate list. The number of bits corresponding to the candidate index can be reduced.

15 is a diagram showing a block position and a motion candidate list configuration according to an embodiment of the present invention.

According to an embodiment of the present invention, the number of possible candidates may be small by referring to motion information at a preset location. For example, according to the situation described in FIG. 14, possible spatial neighbor locations may be reduced. For example, if the current block exists in contact with the top boundary or the left boundary of the range that the reference block can have, the number of possible candidates may be small. In this case, even if the decoder and encoder do not refer to the corresponding spatial neighbor to determine whether it is available (for example, whether the corresponding spatial neighbor location uses intra prediction or inter prediction), the candidate corresponding to the corresponding spatial neighbor is It can be determined that there is no. Also, in this case, the position where the zero MV enters in the candidate list can be pulled forward.

Therefore, according to an embodiment of the present invention, there may be a case where it is possible to determine whether it indicates a zero MV through a candidate index. For example, when some of the spatial neighbor locations are excluded according to the current block location and a range that can be referred to as neighbors, an index that is greater than or equal to all possible candidates may be a zero motion vector. For example, when a zero motion vector is added after the spatial neighboring candidate, it may be determined as a zero motion vector if the index is greater than the number of possible spatial neighboring candidates. For example, if some of the spatial neighbor locations are excluded according to the current block location and the range that can be referred to as a neighbor, if the remaining spatial neighbor locations are M and the index value starting from 0 is M, then the spatial neighboring candidate is added. It can be determined that it is a candidate, and when a zero MV comes after the spatial neighboring candidate, it can be determined that it is a zero MV.

For example, as in the case of the block marked A in FIG. 15, there may be a case in which the current block contacts the left boundary of the range in which the reference block can be located. In this case, as described with reference to FIG. 14, if motion information outside the range in which the reference block can be located is not referenced, the above position of the current block is unavailable. Therefore, only positions other than the above position can be used. Alternatively, in this case, as described in FIG. 14, if motion information outside the range in which the reference block can be located is not referred to, the positions A0, A1, and B2 described in FIG. 12 are not available. Therefore, only B0 and B1 can be used. In an embodiment, in the merge mode, both B0 and B1 may be used, and in the AMVP mode, only one of B0 and B1 may be used. Therefore, in the case of merge mode, if the index is 2 from 0, it can be determined that the candidate is the next candidate after the spatial neighboring candidate. In addition, in the case of AMVP mode, if the index is 1 from 0, it can be determined that it is a candidate that comes after the spatial neighboring candidate. That is, when zero MV comes next to the spatial neighboring candidate, it can be determined that it is zero MV by index.

In addition, there may be a case in which the current block touches the top boundary of the range in which the reference block can be located, as in the case of the block marked B in FIG. 15. In this case, as described with reference to FIG. 14, if motion information outside the range in which the reference block can be located is not referenced, the left position of the current block is unavailable. Therefore, only the positions other than the left position of the current block can be used. Alternatively, in this case, as described with reference to FIG. 14, the positions B0, B1, and B2 described in FIG. 12 cannot be used unless motion information outside the range in which the reference block can be located is referred. Therefore, only A0 and A1 can be used. In an embodiment, in the merge mode, both A0 and A1 can be used, and in the AMVP mode, only one of A0 and A1 can be used. Therefore, in the case of merge mode, if the index is 2 from 0, it can be determined that the candidate is the next candidate after the spatial neighboring candidate. In addition, in the case of AMVP mode, if the index is 1 from 0, it can be determined that it is a candidate that comes after the spatial neighboring candidate. That is, when zero MV comes next to the spatial neighboring candidate, it can be determined that it is zero MV by index.

Referring to FIG. 15, the configuration of an AMVP candidate list when a reference block location is limited to a current CTU range and motion information of a location outside the current CTU is not referenced. When the current block is in contact with the CTU left boundary or top boundary as shown in A or B of FIG. 15, the maximum number of spatial neighboring candidates is possible and the remaining candidates can be filled with zero MV. Therefore, when the candidate index is 1, it can be determined that the MVP is zero MV.

According to an embodiment of the present invention, if it is determined that the zero MV is indicated through the candidate index, the embodiments described in FIGS. 18 to 22 may be performed. For example, MVD coding can be changed. For example, in a specific case, it is possible to determine the code of the MVD component without signaling transmission and syntax parsing.

16 is a diagram showing a block position and a motion candidate list configuration according to an embodiment of the present invention.

According to an embodiment of the present invention, it may not be possible to refer to motion information of a position out of a picture. This can include both the case of using CPR and the case of not using CPR.

According to an embodiment of the present invention, a position that a reference block may have in CPR may be inside a picture. Alternatively, according to an embodiment of the present invention, a location that a reference block may have in CPR may be an area including an inside of a picture.

Referring to FIG. 16, when a current block contacts a picture boundary, a spatial neighbor location may be limited. This may be because motion information of a location outside the picture cannot be referenced. For example, when the current block touches the left boundary of the picture (in the case of the block indicated by A in FIG. 16), the left position of the current block cannot be referenced. In addition, when the current block touches the top boundary of the picture (in the case of the block indicated by B in FIG. 16), the above position of the current block cannot be referenced.

Therefore, in this case, it is possible to reduce the maximum value of binarization or determine that it is zero MV.

As described above, if CPR is used, temporal candidate, scaled candidate, etc. may not be used.

First, referring to the case of using CPR and using the AMVP mode, possible spatial neighbor locations may be limited when the current block is adjacent to the picture boundary as in the present embodiment. In particular, when adjacent to the left boundary or the top boundary, motion information of the left positions of the current block and the above positions of the current block cannot be referenced. Therefore, when constructing the AMVP candidate list, the available spatial candidate can be maximum 1. If the value indicated by the candidate index (may be a flag when the maximum number of candidates is 2) is 1 (when the candidate index starts from 0), the motion vector corresponding to the candidate index is determined to be a zero motion vector. I can.

In the case of using the merge mode, when the current block is adjacent to the picture boundary as in the present embodiment, possible spatial neighbor locations may be limited. In particular, when adjacent to the left boundary or the top boundary, motion information of the left positions of the current block and the above positions of the current block cannot be referenced. Therefore, according to the embodiment of FIG. 12, the maximum number of positions that can be referred to may be two. Therefore, it can be determined that the motion vector corresponding to the case where the merge candidate index is greater than or equal to the referenceable maximum number is not from the spatial neighboring candidate.

If only the spatial neighboring candidate and zero MV are used in the merge mode using CPR, in the above case, the zero MV can be determined through the candidate index. However, in CPR merge mode, since zero MV may not be meaningful, the maximum value of the candidate index, which is a variable length, can be set with (the number of possible spatial neighboring candidates-1). In this way, the number of bits of a certain index value can be reduced.

In another embodiment, in a merge mode using CPR, spatial neighboring candidate, HMVP candidate, pairwise average candidate, etc. may be included in the candidate list. In this case, if the maximum possible number of spatial neighboring candidates is limited as in the above-described embodiment, the number of possible pairwise average candidates may also be reduced. This is because the combination of spatial neighboring candidates can be reduced. If there are two possible spatial neighboring candidate positions in the embodiment as shown in FIGS. 12 and 16, the number of possible pairwise average candidates may be one. In addition, there may be a preset part where the space for storing history in HMVP is reset. For example, the space for storing history in HMVP can be reset for each CTU row. This may be to facilitate parallel processing. This is because the encoder and decoder must be able to maintain the same history. Therefore, the HMVP candidate cannot be added to the candidate list in the preset part where the space for storing history in HMVP is reset. If CPR is used and the spatial neighbor location is limited, if the space for storing history in HMVP is reset, the maximum number of possible candidates may be further reduced. For example, spatial neighbor positions in the left boundary of a picture may be limited to a maximum of two, and a space storing history in HMVP may be reset at the beginning of a CTU row. In this case, up to two spatial neighboring candidates may be included in the candidate list, and HMVP candidates may be included. Even if a pairwise average candidate can be added, only one combination appears when creating a pairwise average. Therefore, when pairwise average candidates can be added, there can be a maximum of 3 candidates and a zero motion vector. If the pairwise average candidate cannot be added, there may be a maximum of two candidates and a zero motion vector. Accordingly, it is possible to reduce the maximum value of the candidate index than before and to reduce the number of bits of the index.

In another embodiment, when CPR is used, it is possible not to use a pairwise average candidate. This is because, when CPR is used, a useful motion vector may be limited compared to when CPR is not used.

In another embodiment, when the current block is adjacent to the left boundary of the picture, the HMVP candidate may not be used. Alternatively, when the current block is adjacent to the boundary where the HMVP history is reset (for example, when the reset position and the x coordinate of the current block left-top are the same), the HMVP candidate may not be used. If the space for storing HMVP history is reset at the beginning of the CTU row, motion information may not vary in history when coding the CTU at the far left of the picture. Therefore, in the case of a block adjacent to the picture left boundary, the x component of the motion vector must be 0 or plus. Also, at this point, the direction of the motion vector stored in the history is limited, so it may be difficult to utilize the block adjacent to the left boundary. Therefore, when the current block is adjacent to the picture left boundary, the HMVP candidate may not be used. In this case, when combined with the above embodiment, it is possible to add up to two spatial neighboring candidates, up to one pairwise average candidate, and zero MV to the merge candidate list for blocks adjacent to the left boundary of the picture. Therefore, if zero MV can be added, the maximum value of the index is 3 (when the index starts from 0), and if zero MV cannot be added, the maximum value of the index is binarized to 2 (when the index starts from 0). can do.

According to an embodiment of the present invention, it is determined that the current block is adjacent to the left, right, top, and bottom boundary of the picture, such as coordinates of the current block, width of the current block, height of the current block, width of the current picture, height of the current picture, etc. It can be judged on the basis of. The top-left coordinates of the current block can be called (x0, y0). The width and height of the current block can be called cbWidth and cbHeight, respectively. The width and height of the current picture can be called picWidth and picHeight, respectively. If (x0 == 0) is true, it may be adjacent to the picture left boundary. If ((x0 + cbWidth) == picWidth) is true, it may be adjacent to the picture right boundary. If (y0 == 0) is true, it may be adjacent to the picture top boundary. If ((y0 + cbHeight) == picHeight) is true, it may be adjacent to the picture bottom boundary.

Although described as the case of using CPR, it is possible to perform the above operation when the temporal motion vector cannot be used even if CPR is not used, or when the reference picture of the neighboring block and the reference picture of the current block match.

17 is a diagram showing the use of a spatial neighboring candidate according to an embodiment of the present invention.

According to an embodiment of the present invention, there may be a case where a spatial neighbor location cannot be used. If a preset location performs intra prediction, motion information may not be referenced from the location. Accordingly, according to an embodiment of the present invention, the number of possible spatial neighboring candidates can be reduced according to whether or not predetermined spatial neighboring positions have used intra prediction. Alternatively, the number of possible spatial neighboring candidates may be reduced according to whether inter prediction that preset spatial neighbor locations can refer to is used. For example, the number of possible spatial neighboring candidates can be reduced depending on whether pre-set spatial neighboring locations have used inter prediction using CPR.

For example, in the AMVP mode, there may be cases in which all left positions among spatial neighboring positions are intra-predicted, or all above positions are intra-predicted (except for parts outside the picture or undecoded positions). Or, in the case of AMVP mode, if inter prediction that all left positions among spatial neighbors can refer to, or not inter prediction that all of the above positions can refer to (except for parts outside the picture or not decoded) There may be.) That is, there may be a case where motion information cannot be referenced in all of the left positions or all of the above positions. In this case, when only one of the left position or the above position can be referenced, the number of possible spatial neighboring candidates is 1, and when the index is 1, it can be determined that it is zero MV. Alternatively, when both the left and above positions cannot be referenced (for example, when all preset positions are performed intra prediction as shown in FIG. 17), the number of possible spatial neighboring candidates is 0, and when the index is 0, it is determined that it is zero MV. I can judge. Alternatively, when neither the left position nor the above position is referenced (for example, when all preset positions are performed intra prediction as shown in FIG. 17), the number of possible spatial neighboring candidates is 0, and index transmission and parsing may be omitted. . And you can infer the index to 0, zero MV.

As another example, when motion information among preset spatial neighbor locations cannot be referenced, it is possible to exclude the location in the syntax parsing step and change the number of maximum candidates. The case where motion information cannot be referred may include a case in which the corresponding position uses intra prediction. Alternatively, the case where motion information cannot be referenced may include a case where a corresponding position deviates from a picture or is not decoded due to coding order.

If it is assumed that motion information cannot be referenced at all preset positions in merge mode, a spatial neighboring candidate may not be added to the candidate list. Therefore, it may be possible to use HMVP candidate, pairwise average candidate, etc. as candidates. At this time, if the current block is in a position to reset the space for storing the history of HMVP described in the previous figure, the HMVP candidate may not be added as well. In addition, if the pairwise average candidate precedes the HMVP candidate or if the HMVP candidate cannot be added, the pairwise average candidate may also not appear. Therefore, only zero MV can remain as a possible candidate. However, zero MV may be meaningless in CPR. In this case, signaling indicating merge mode may be omitted (transmission and parsing omitted). And you can infer by not using the merge mode. For example, the signaling indicating the merge mode may be merge_flag. Accordingly, according to an embodiment of the present invention, when CPR is used, all preset spatial neighbor locations around the current block are not available (if the location is out of the picture, the location is intra prediction, the location is CPR). If the current block is a location where the HMVP history storage space is reset, the signaling indicating merge mode can be omitted and inferred to not using the merge mode. have. The location where the space for storing HMVP history is reset may be a location where the CTU row starts or a location previously set not to use the HMVP candidate.

As another example, there may be a case where motion information cannot be referenced except for one of the preset spatial neighbor locations. The case where motion information cannot be referred may include a case where a corresponding position deviates from a picture, a case where the corresponding position performs intra prediction, a case where the corresponding position does not use CPR, and the like. Even in this case, as in the previous embodiment, if other candidates other than one spatial neighboring candidate are not added, it may not be possible to create a pairwise average candidate. Also, the HMVP candidate may not be included because the location where the HMVP history is stored is reset. Therefore, binarization can be performed by changing the maximum value of the candidate index at this location. For example, motion information cannot be referenced in all other locations except for one of the preset spatial neighbor locations, and in the part that resets the space for storing HMVP history, there is a maximum of 1 spatial neighboring candidate and the maximum number of HMVP candidates. 0, pairwise average candidates can be made up to 0. Therefore, in an embodiment in which zero MV can be added to the candidate, candidate index signaling is possible with a flag of 1 bit. However, in this case, it is possible to skip transmitting and parsing the candidate index and infer to 0. This is because zero MV may be meaningless in CPR. In addition, in an embodiment in which zero MV cannot be added to a candidate, there may be only one possible candidate, and in this case, it is possible to skip transmitting and parsing the candidate index and infer to 0.

18 is a diagram showing a motion vector according to an embodiment of the present invention.

According to an embodiment of the present invention, a value that a motion vector can have may be limited according to a coding order. Also, this may be the case using CPR. For example, the motion vector may not point in the lower right direction depending on the coding order. This is because the block on the right or below the current block is not decoded according to the block coding order. Therefore, according to an embodiment of the present invention, when using CPR, the x component of the motion vector may be 0 or more and the y component may not be 0 or more. That is, when using CPR, the motion vector may not be (x component >= 0 && y component >= 0).

In addition, according to the embodiments described with reference to FIGS. 14 to 17, there may be a case where the MVP is zero MV. Particularly, the fact that MVP is zero MV can be known at the syntax parsing step. In this case, the motion vector difference (MVD) may not point in the lower right direction. That is, the MVD may not be (x component >= 0 && y component >= 0). In another embodiment, the MV may not be (x component> -(current block width) && y component> (-current block height)). That is, when zero MV is used as MVP, the MVD may not be (x component> -(current block width) && y component> (-current block height)). Accordingly, according to an embodiment of the present invention, there may be a case in which the range of the y component value can be limited according to the x component value of the MV or MVD.

According to an embodiment, the components of the MVD may be divided and coded. For example, the MVD can be coded as described in FIG. 9. For example, component 1 and component 2 can be divided and coded. In addition, for example, component 1 and component 2 can be coded in order. In an embodiment, component 1 and component 2 may be x-component and y-component, respectively. The following embodiments may be a case where the MVP is zero MV.

According to an embodiment of the present invention, if component 1 is greater than 0, component 2 may be less than 0. More specifically, if component 1 is greater than 0, the absolute value of component 2 may be greater than or equal to the minimum block size. Also, if component 1 is greater than 0, the absolute value of component 2 may be higher than the current block height.

According to an embodiment of the present invention, if component 1 is 0, component 2 may not be 0. Also, if component 1 is 0, component 2 may be smaller than 0. More specifically, if component 1 is 0, the absolute value of component 2 may be greater than or equal to the minimum block size. Also, if component 1 is 0, the absolute value of component 2 may be higher than the current block height.

According to an embodiment of the present invention, when component 1 is less than 0 and an absolute value is less than minimum block size, component 2 may not be 0. Also, in this case, component 2 may be less than 0. More specifically, in this case, the absolute value of component 2 may be greater than or equal to the minimum block size. Also, in this case, the absolute value of component 2 may be greater than or equal to the current block height.

According to an embodiment of the present invention, when component 1 is less than 0 and the absolute value is less than the current block width, component 2 may not be 0. Also, in this case, component 2 may be less than 0. More specifically, in this case, the absolute value of component 2 may be greater than or equal to the minimum block size. Also, in this case, the absolute value of component 2 may be greater than or equal to the current block height.

Referring to FIG. 18, the x-component value of MV in the current block may be the same as that shown in the drawing. In that case, the reference block of CPR may be made to enter the area indicated by the shade in FIG. 18. Therefore, the range of values that the y-component can have can be limited. That is, it is possible to limit the value of the y-component according to the value of the x-component.

19 is a diagram showing a motion vector difference syntax according to an embodiment of the present invention.

As described in FIG. 9, the MVD may be divided into x-component and y-component and coded. Referring to FIG. 19, values corresponding to [0] and [1] may be x-component and y-component, respectively. Also, abs_mvd_greater0_flag may be a flag indicating whether the absolute value of the corresponding component is greater than 0. Also, abs_mvd_greater1_flag may be a flag indicating whether the absolute value of the corresponding component is greater than 1 or not. Also, abs_mvd_minus2 may be a value obtained by subtracting 2 from the absolute value of the corresponding component. Also, mvd_sign_flag may be a flag indicating a sign of a corresponding component. In addition, a value of mvd_sign_flag 0 may indicate plus and a value of 1 may indicate minus.

The embodiments described in FIG. 18 may be reflected in the MVD coding syntax of FIG. 19.

In FIG. 19, the “zeroMVP” condition may indicate a case where MVP is zero MV and may indicate a case of using CPR. That is, when MVP is zero MV and CPR is used, zeroMVP may be true. The condition in which the MVP is zero MV may follow the embodiments described in FIGS. 14 to 17. According to the previous embodiments, that the MVP is zero MV may be based on the location of the current block or the candidate index.

According to an embodiment of the present invention, in the case of zeroMVP, if x-component is 0, y-component may not be 0. Therefore, in this case, abs_mvd_greater0_flag[ 1] may not be parsed. Also, in this case, abs_mvd_greater0_flag[1] can be inferred to a value indicating non-zero. Also, in this case, abs_mvd_greater0_flag[ 1] can be inferred to 1.

According to an embodiment of the present invention, in the case of zeroMVP, if the x-component is 0, the absolute value of the y-component may be greater than 1. This may be because the current block height is greater than 1. Therefore, in this case, abs_mvd_greater1_flag[ 1] may not be parsed. Also, in this case, abs_mvd_greater1_flag[ 1] may be inferred to a value indicating that the absolute value is greater than 1. Also, in this case, abs_mvd_greater1_flag[ 1] can be inferred to 1. In the existing MVD coding before CPR, since abs_mvd_greater1_flag inferred to 0 when abs_mvd_greater1_flag does not exist, when combined with this embodiment, the infering value when abs_mvd_greater1_flag does not exist can be divided according to conditions. For example, when abs_mvd_greater1_flag[compIdx] does not exist, if abs_mvd_greater0_flag[compIdx] is 0, it can infer to 0, and if abs_mvd_greater1_flag[compIdx] is 1, it can infer to 1. Or, for example, when abs_mvd_greater1_flag[compIdx] does not exist, if abs_mvd_greater0_flag[compIdx] is 0, it may be inferred to 0. Or, if abs_mvd_greater1_flag[compIdx] does not exist and abs_mvd_greater0_flag[!compIdx] is 0, it can be inferred to 1.

According to an embodiment of the present invention, in the case of zeroMVP, if x-component is positive or 0, y-component may be negative. Therefore, in this case, the mvd_sign_flag of the y-component may not be parsed. Also, in this case, mvd_sign_flag may be inferred to a value indicating a negative number. In this case, mvd_sign_flag can be inferred to 1. Therefore, if it is zeroMVP and mvd_sign_flag[0] is 0, mvd_sign_flag[1] can be inferred to 1 without parsing. In addition, if it is zeroMVP and abs_mvd_greater0_flag[0] is 0, mvd_sign_flag[1] can be inferred to 1 without parsing.

Also, if mvd_sign_flag does not exist before CPR, it may have inferred to 0. However, when mvd_sign_flag does not exist in the past (refer to the embodiment of FIG. 9), there may be only a case where the absolute value of the corresponding component is 0. Therefore, in combination with the embodiment of the present invention, if mvd_sign_flag does not exist, it can be unified by infering to 1. In another embodiment, the value of mvd_sign_flag infer may be different according to conditions. For example, in case of zeroMVP && (mvd_sign_flag[0] == 0 || abs_mvd_greater0_flag[ 0] == 0), it can infer to 1, otherwise it can infer to 0.

20 is a diagram showing a motion vector according to an embodiment of the present invention.

According to an embodiment of the present invention, a value that a motion vector can have may be limited according to a range in which a reference block can be located. Also, this may be the case using CPR. For example, a motion vector may be set so as not to deviate from a range in which a reference block can be located.

For example, when the current block is adjacent to a boundary within a range in which the reference block can be located, the motion vector may be in the opposite direction of the adjacent boundary. That is, when the current block is adjacent to the left boundary or the right boundary of the range in which the reference block can be located, the x-component may be 0 or more and 0 or less, respectively. In addition, when the current block is adjacent to the top boundary or the bottom boundary within the range where the reference block can be located, the y-component may be 0 or more and 0 or less, respectively. In addition, according to an embodiment, the range in which the reference block can be located may be the CTU range to which the current block belongs.

In addition, according to the embodiments described with reference to FIGS. 14 to 17, there may be a case where the MVP is zero MV. Particularly, the fact that MVP is zero MV can be known at the syntax parsing step. In this case, the above description of the motion vector can be applied to MVD.

Referring to FIG. 20, a position that a reference block of CPR may have may be limited within a CTU to which a current block belongs. In this case, when the current block is adjacent to the left boundary as indicated by A, the x-component of the motion vector may be 0 or more. In addition, when the current block is adjacent to the top boundary such as the position indicated by B, the y-component of the motion vector may be 0 or more.

21 is a diagram showing a motion vector difference syntax according to an embodiment of the present invention.

As described in FIG. 9, the MVD may be divided into x-component and y-component and coded. Referring to FIG. 21, values corresponding to [0] and [1] may be x-component and y-component, respectively. Also, abs_mvd_greater0_flag may be a flag indicating whether the absolute value of the corresponding component is greater than 0. Also, abs_mvd_greater1_flag may be a flag indicating whether the absolute value of the corresponding component is greater than 1 or not. Also, abs_mvd_minus2 may be a value obtained by subtracting 2 from the absolute value of the corresponding component. Also, mvd_sign_flag may be a flag indicating a sign of a corresponding component. In addition, a value of mvd_sign_flag 0 may indicate plus and a value of 1 may indicate minus.

The embodiments described in FIG. 20 may be applied to the MVD coding syntax of FIG. 21.

In FIG. 21, the “zeroMVP” condition may indicate a case in which MVP is zero MV, and may indicate a case in which CPR is used. That is, when MVP is zero MV and CPR is used, zeroMVP may be true. The condition in which the MVP is zero MV may follow the embodiments described in FIGS. 14 to 17. According to the previous embodiments, that the MVP is zero MV may be based on the location of the current block or the candidate index.

Referring to FIG. 21, conditions indicating neighboring left, right, top, and bottom boundaries are represented as left_boundary, right_boundary, top_boundary, and bottom_boundary, respectively. Also, what is adjacent to the boundary can be determined based on the coordinates of the current block, the width of the current block, the height of the current block, the width of the range possible as the position of the reference block, and the height of the range possible as the position of the reference block. For example, the top-left coordinates of the current block can be expressed as (x0, y0). In addition, the width and height of the current block can be expressed as cbWidth and cbHeight, respectively. In addition, the width and height of the range possible as the location of the reference block can be expressed as rWidth and rHeight, respectively. For example, if (x0% rWidth == 0) is true, it may be adjacent to the left boundary. If ((x0 + cbWidth)% rWidth == 0) is true, it may be adjacent to the right boundary. If (y0% rHeight == 0) is true, it may be adjacent to the top boundary. If ((y0 + cbHeight)% rHeight == 0) is true, it may be adjacent to the bottom boundary. In addition, according to an embodiment, rWidth and rHeight may be CTU(CTB) width and height.

As described in FIG. 20, there is a case where the sign of the MVD can be determined when it is zeroMVP and is adjacent to the boundary. For example, in the case of zeroMVP and left_boundary, mvd_sign_flag[0] may not be parsed, and may be inferred to a value indicating plus (eg 0).

In addition, in the case of zeroMVP and right_boundary, mvd_sign_flag[0] may not be parsed, and may be inferred to a value indicating minus (eg 1).

In addition, in the case of zeroMVP and top_boundary, mvd_sign_flag[1] may not be parsed, and may be inferred to a value indicating plus (eg, 0).

In addition, in the case of zeroMVP and bottom_boundary, mvd_sign_flag[1] may not be parsed and may be inferred to a value representing minus (eg 1).

In addition, in FIGS. 9, 19, and 21, abs_mvd_greater0_flag, abs_mvd_greater1_flag, abs_mvd_minus2, mvd_sign_flag are coded in this order. As the order is changed, other embodiments may be performed. It is possible to infer any syntax without parsing based on the current block position, whether zeroMVP, the range in which the reference block can be located, and other syntax values that are already known.

22 is a diagram showing a motion vector difference syntax according to an embodiment of the present invention.

Referring to FIG. 22, the embodiments described in FIGS. 18 to 21 may be combined. Accordingly, the number of bits required for mvd_coding can be reduced.

In addition, according to an embodiment of the present invention, in the case of zeroMVP, after the absolute value of the MVD of a component is determined, it is possible to determine the sign of the MVD without parsing so that the MVD value does not indicate a reference block exceeding the possible range. For example, as in the embodiments of FIGS. 9, 19, and 21, the absolute value may be determined before determining the sign of the MVD. If |MVD| of a component exceeds the possible range, the sign can be determined as minus. Also, if -|MVD| of a component exceeds the possible range, the sign can be determined as plus.

23 is a diagram showing a block and a size according to an embodiment of the present invention.

According to an embodiment of the present invention, there may be a case where the width or height of the current block is the maximum width or the maximum height. In this case, motion information may not be referenced at a preset spatial neighbor location. This may be according to the coding order. For example, if the width of the current block is the maximum width, motion information may not be referenced from the right position of the current block. In the case of the embodiment of FIG. 12, motion information may not be referenced from B0. As another example, when the height of the current block is the maximum height, motion information may not be referenced from the bottom position of the current block. In the case of the embodiment of FIG. 12, it may not be possible to refer to motion information from A0.

If the embodiment of FIG. 23 is combined with the embodiment of FIG. 14, the number of spatial neighbor locations that can refer to motion information can be reduced to one. For example, when it is adjacent to the left boundary and has a maximum width, motion information may not be referenced from A0, A1, B0, and B2 of FIG. 12. Also, if it is adjacent to the top boundary and has a maximum height, motion information from A0, B0, B1, and B2 may not be referenced. Therefore, in this case, possible spatial neighbor locations are reduced, and thus it is possible to perform embodiments such as determining zero MV, omitting candidate index parsing, or binarizing the maximum value of the candidate index, as in the previous embodiments.

24 is a diagram showing the configuration of a merge candidate list according to an embodiment of the present invention.

According to an embodiment of the present invention, when CPR is used, a method of configuring a merge candidate list may be different from that of not using CPR. For example, if CPR is not used and some of the candidates that can be added to the merge candidate list use CPR, they may not be added to the merge candidate list.

In an embodiment, when CPR is used, zero MV may not be used. This is because the reference block indicated by the zero MV in the current picture can be the current block.

In an embodiment, when CPR is used, temporal MV (collocated MV) may not be used. This is because when using CPR, a picture other than the current picture may not be referenced.

In an embodiment, when CPR is used, the HMVP candidate or the pairwise average candidate may not be used. In this case, it is possible to change the index signaling as described in the embodiments of the preceding drawings.

As an embodiment, when using CPR, it is possible to use a candidate based on an HMVP candidate or a pairwise average candidate.

In an embodiment, when CPR is used, the subblock merge mode may not be used. Subblock merge mode may be the same as described above. Accordingly, in the case of using CPR, it is possible to infer the flag indicating the subblock merge mode without parsing.

According to an embodiment of the present invention, when CPR is used, a preset set of spatial neighbor locations may be different from a preset set of spatial neighbor locations when CPR is not used. According to an embodiment of the present invention, when CPR is used, one of B0 and B1 may not be used at a preset position of FIG. 12. For example, when using CPR, motion information may not be referenced from the B0 position. Alternatively, according to an embodiment of the present invention, when CPR is used, one of A0 and A1 may not be used at a preset position of FIG. 12. For example, when using CPR, motion information may not be referenced from the A0 position. This is because motion information in the case of using CPR is relatively complex and may not require various things. Or, when CPR is used, motion information from a nearby location may be similar.

25 is a diagram showing a block location and syntax according to an embodiment of the present invention.

According to an embodiment of the present invention, when CPR is used, zero MV may not be used as MVP in AMVP mode. In this case, when combined with the embodiment of FIG. 15, there may be a case where only one spatial candidate is added to the candidate list according to the current block position. Also, if zero MV is not used as an MVP, only one candidate can exist in the MVP candidate list. In this case, it is possible not to pars the candidate index. Also, in this case, the candidate index can be inferred to 0.

Referring to FIG. 25, (a) shows a case in which the current block is adjacent to the left boundary or the top boundary of the range that the reference block can have. In this case, motion information from a position outside the range that the reference block can have may not be referenced. In this case, when using the AMVP mode, when zero MV is not used as an MVP, the maximum number of possible MVP candidates can be one. Therefore, in such a case as shown in FIG. 25(b), mvp_l0_flag and mvp_l1_flag indicating the candidate index may not be parsed. At this time, you can infer to 0. The case of using CPR is indicated by CurrPicIsOnlyRef. Also, l0 and l1 may represent reference lists 0 and 1, respectively. In addition, when CPR is used, since the current picture may be the only reference picture, MV may exist for only one reference list. At this time, MV-related syntax can also be parsed for only one reference list.

26 is a view showing resetting a space for storing HMVP history according to an embodiment of the present invention.

As described above, the space for storing HMVP history at a preset location can be reset. The space for storing the history of the HMVP may be called an HMVP table.

According to an embodiment of the present invention, the preset position may be different when CPR is used and when CPR is not used. For example, if CPR is not used, the HMVP table can be reset at the beginning of the CTU row. In addition, for example, when using CPR, the HMVP table can be reset at the beginning of the range in which the reference block can exist. Alternatively, for example, when using CPR, the HMVP table can be reset at the beginning of each CTU. Alternatively, when CPR is used, there may be more (often) preset locations for resetting the HMVP table than when CPR is not used.

This is because when CPR is used, motion information corresponding to a position far from the current block may have little correlation with the present. In addition, when CPR is used, parallel processing can be made easier by performing HMVP table reset more frequently.

Referring to FIG. 26, each small square in the drawing may indicate a range in which a reference block may exist or a CTU range. In addition, a portion marked with an X may be a portion in which the HMVP table is reset. If the CPR shown in the upper part of FIG. 26 is not used, the HMVP table can be reset at the beginning of the CTU row. When the CPR shown in the lower part of FIG. 26 is used, the HMVP table can be reset at the beginning of the CTU.

According to an embodiment of the present invention, the MVD coding method in the case of using CPR may be different from the MVD coding method in the case of not using CPR. For example, when CPR is not used, a coding method as shown in FIG. 9 can be used. This is because in the case of using CPR, the range of possible MVs according to the coding order may be different from that in the case of not using CPR.

In the case of using CPR as an embodiment, a method of separately coding an x-component and a y-component may not be used. For example, a coding scheme based on the absolute value and direction of a vector can be used.

In the case of using CPR as an embodiment, the reference point indicated by the MV when the MVP is zero MV may be different from the existing (a vector from the current block top-left).

In the case of using CPR as an embodiment, a syntax different from that described in FIGS. 9, 19, and 21 may be used. For example, in a flag indicating whether the absolute value is greater than what value, a case in which CPR is used may differ from the case in which CPR is not used. Accordingly, signaling of a value obtained by subtracting a certain value from the absolute value can be performed. For example, there was a flag indicating whether the absolute value was greater than 1 in the previous embodiments. For example, when CPR is used, there may be a flag indicating whether the absolute value is greater than the minimum block size. Alternatively, when using CPR, a flag indicating whether the width or height of the current block is larger can be used. For example, when CPR is used, a flag indicating whether the absolute value is greater than the current block width for x-component, and a flag indicating whether the absolute value is greater than the current block height for y-component can be used.

According to an embodiment of the present invention, when CPR is used, a shared merge list may not be used. The shared merge list may be a technique in which a plurality of blocks (eg, coding units) use the same merge list. This can use a shared merge list to facilitate parallel processing. However, in the case of using CPR, since the current picture is used as a reference block, the corresponding part of the current picture must be reconstruction, and it may not be of great significance to facilitate parallel processing. Also, in the case of using CPR, if the shared merge list is used, accuracy may decrease or the number of available candidates may be too small.

According to another embodiment, when CPR is used, a criterion for grouping blocks using the same merge list in a shared merge list may be different from that when CPR is not used.

According to an embodiment of the present invention, when CPR is used, some of the methods used when CPR is not used may not be used. Alternatively, according to an embodiment of the present invention, when CPR is used, some of the methods used when CPR is not used may be used differently. When the CPR is not used, the method used may include a prediction mode.

27 is a diagram showing a coding unit syntax according to an embodiment of the present invention.

The CPR described above may also be called IBC (intra block copy).

According to an embodiment of the present invention, IBC may exist as an independent prediction mode. That is, the aforementioned intra prediction and inter prediction may be MODE_INTRA and MODE_INTER, respectively, and MODE_IBC different from MODE_INTRA and MODE_INTER may exist. Also, as shown in the preceding figures, MODE_INTRA, MODE_INTER, and MODE_IBC may be represented by CuPredMode values.

In addition, the tile group may be a unit higher than the CU, CTU, or PU. Also, the tile group may be a unit capable of parallel processing.

The B (bi-predictive) tile group may use intra prediction, inter prediction, IBC, or the like. Also, in the B tile group, it is possible to use up to two motion vectors and two reference indices each in the block. Alternatively, in the B tile group, it is possible to use more than one motion vector and one reference index each in the block.

Also, intra prediction may be a concept including an IBC technique. Intra prediction may be a prediction method that refers only to the current picture. In addition, inter prediction may be a method of referencing a picture other than the current picture as a reference picture.

The P (predictive) tile group may use intra prediction, inter prediction, IBC, or the like. In addition, it is possible to use up to one motion vector and one reference index in the block for the P tile group. Alternatively, in the B tile group, it is possible not to use more than two motion vectors and reference indexes respectively in the block.

The I (intra) tile group may use intra prediction or IBC. Also, the I tile group may not refer to a picture other than the current picture as a reference picture.

According to an embodiment of the present invention, in the case of (tile_group_type! = I | | sps_ibc_enabled_flag ), it is possible that there is a possibility of parsing cu_skip_flag, pred_mode_flag, and pred_mode_ibc_flag. That is, if (tile_group_type != I | | sps_ibc_enabled_flag) is not, it is possible not to pars all of cu_skip_flag, pred_mode_flag, and pred_mode_ibc_flag.

Also, sps_ibc_enabled_flag may be a high-level signaling indicating whether IBC is used. In addition, when sps_ibc_enabled_flag is set to 0, IBC is not used, and when it is set to 1, IBC can be used.

In addition, it may be determined whether the skip mode is used based on the cu_skip_flag value. If cu_skip_flag is 1, skip mode may be used.

In addition, it is possible to determine the prediction mode based on pred_mode_flag or pred_mode_ibc_flag. That is, it is possible to determine whether the current mode is MODE_INTRA, MODE_INTER, or MODE_IBC based on pred_mode_flag or pred_mode_ibc_flag. Alternatively, the CuPredMode value may be determined based on pred_mode_flag or pred_mode_ibc_flag.

In addition, tile_group_type may indicate the type of tile group. As described above, the tile group type may include an I tile group, a P tile group, and a B tile group. In addition, if the tile_group_type value is I, P, and B, it may represent an I tile group, a P tile group, and a B tile group, respectively.

According to an embodiment of the present invention, in the case of (cu_skip_flag[ x0 ][ y0] = = 0 && tile_group_type != I)), it is possible to pars the pred_mode_flag. Also, when cu_skip_flag is 1, pred_mode_flag may not be parsed. In addition, when tile_group_type is I, pred_mode_flag may not be parsed.

According to an embodiment of the present invention ((tile_group_type = = I && cu_skip_flag[ x0 ][ y0] = = 0) || (tile_group_type! = I && (cu_skip_flag[ x0 ][ y0] | | CuPredMode[ x0 ][ y0 ] != MODE_INTRA)) In case of && sps_ibc_enabled_flag && blockSizeCondition ), it is possible to pars pred_mode_ibc_flag. For example, in the case of (tile_group_type = = I && cu_skip_flag[ x0 ][ y0] == 0 ), it is possible to pars pred_mode_ibc_flag. Or, in the case of (tile_group_type != I && (cu_skip_flag[ x0 ][ y0] | | CuPredMode[ x0 ][ y0] != MODE_INTRA) ), it is possible to pars pred_mode_ibc_flag. Or (tile_group_type = = I && cu_skip_flag[ x0 ][ y0] == 0 ), nor (tile_group_type != I && (cu_skip_flag[ x0 ][ y0] | | CuPredMode[ x0 ][ y0] != MODE_INTRA)) If not, it is possible not to pars the pred_mode_ibc_flag. In addition, when sps_ibc_enabled_flag is 1, pred_mode_ibc_flag can be parsed, and when sps_ibc_enabled_flag is 0, it is possible not to pars pred_mode_ibc_flag. In addition, there may be a condition based on a block size capable of parsing pred_mode_ibc_flag. Referring to FIG. 27, the block size condition is shown as a case where both cbWidth and cbHeight are less than 32.

Also, referring to FIG. 27, when CuPredMode is MODE_INTRA, it is possible to pars an intra prediction related syntax element. Also, when CuPredMode is MODE_INTRA, it is possible not to pars the syntax element related to the motion vector.

In addition, when CuPredMode is not MODE_INTRA, syntax elements related to inter prediction can be parsed. Also, when CuPredMode is not MODE_INTRA, IBC related syntax elements can be parsed. The syntax element related to IBC may include a syntax element related to a motion vector. That is, when CuPredMode is MODE_IBC, IBC-related syntax elements can be parsed. IBC-related syntax elements may include merge mode-related syntax elements and AMVP-related syntax elements. In addition, the prediction mode for IBC may be more limited than in the case of MODE_INTER, and there may be fewer syntax elements for parsing. For example, in the case of MODE_IBC, it is possible to pars only the syntax element for the reference list L0. As another example, in the case of MODE_IBC, some of the flags indicating whether to use the mode in merge_data may not be parsed. In addition, when CuPredMode is not MODE_INTRA, parsing an inter prediction-related syntax element and parsing an IBC-related syntax element may be a case in which syntax for a chroma component is not parsed. Alternatively, when CuPredMode is not MODE_INTRA, parsing an inter prediction related syntax element and parsing an IBC related syntax element may be performed when the treeType is not DUAL_TREE_CHROMA.

In one embodiment, it is possible to determine which component syntax is parsed, which component is processed, and the like by treeType. If the treeType is SINGLE_TREE, the luma component and the chroma component can share the syntax element value. Also, if treeType is SINGLE_TREE, luma block and chroma block can be partitioned in the same way. If the treeType is DUAL_TREE, it is possible to partition the luma block and chroma block in different ways. In addition, the treeType of DUAL_TREE may include DUAL_TREE_LUMA and DUAL_TREE_CHROMA. Depending on whether the treeType is DUAL_TREE_LUMA or DUAL_TREE_CHROMA, it is possible to determine whether to process a luma component or a chroma component.

28 is a diagram illustrating prediction mode signaling according to an embodiment of the present invention.

According to an embodiment of the present invention, a prediction mode may be indicated based on pred_mode_flag. Also, it is possible to determine CuPredMode based on pred_mode_flag. In addition, it is possible to indicate whether it is inter prediction or intra prediction based on pred_mode_flag.

According to an embodiment of the present invention, if pred_mode_flag is 0, CuPredMode may be set to MODE_INTER. Also, if pred_mode_flag is 1, CuPredMode may be set to MODE_INTRA. According to an embodiment, pred_mode_flag may indicate whether the current CU is in an inter prediction mode or an intra prediction mode.

If pred_mode_flag does not exist, it is possible to infer pred_mode_flag or CuPredMode. If pred_mode_flag does not exist, it is possible to infer pred_mode_flag or CuPredMode based on which tile group it is. For example, in the case of I tile group, it is possible to infer CuPredMode to MODE_INTRA. In addition, in the case of a P tile group or a B tile group, it is possible to infer CuPredMode to MODE_INTER.

According to an embodiment of the present invention, a prediction mode may be indicated based on pred_mode_ibc_flag. In addition, it is possible to determine CuPredMode based on pred_mode_ibc_flag. In addition, it is possible to indicate whether the IBC mode is based on pred_mode_ibc_flag.

According to an embodiment of the present invention, when pred_mode_ibc_flag is 0, CuPredMode may be set to MODE_INTER. Also, when pred_mode_ibc_flag is 1, CuPredMode may be set to MODE_IBC. Alternatively, when pred_mode_ibc_flag is 0, CuPredMode may be set to a value other than MODE_IBC.

If pred_mode_ibc_flag does not exist, it is possible to infer pred_mode_ibc_flag or CuPredMode. If pred_mode_ibc_flag does not exist, it is possible to infer pred_mode_ibc_flag or CuPredMode based on which tile group it is. For example, in the case of I tile group, it is possible to infer CuPredMode to MODE_INTRA. In addition, in the case of a P tile group or a B tile group, it is possible to infer CuPredMode to MODE_INTER.

In the present invention, what is used as a tile group can be replaced with a unit capable of slice or other parallel processing other than the tile group.

According to an embodiment of the present invention, it is possible to use the skip mode when using IBC. For example, in the case of using IBC for the I tile group, it is possible to use the skip mode. For example, it is possible to use the skip mode for CUs that use IBC for the I tile group. However, the syntax and signaling methods described in FIGS. 27 to 28 may not support this. For example, in the I tile group, it can be assumed that the IBC mode is in the skip mode. In that case, sps_ibc_enabled_flag may be 1. Also, cu_skip_flag can be parsed. In this case, the value of cu_skip_flag may be 1 (a value indicating the use of the skip mode). In addition, cu_skip_flag may be 1 or pred_mode_flag may not be parsed for I tile group. In that case, it is possible to infer CuPredMode to MODE_INTRA for the I tile group. In addition, if it is an I tile group and cu_skip_flag is 1, pred_mode_ibc_flag may not be parsed. In that case, it is possible to infer CuPredMode to MODE_INTRA for the I tile group. Therefore, even though IBC is used, a situation in which CuPredMode cannot be expressed as MODE_IBC may occur.

29 is a diagram illustrating prediction mode signaling according to an embodiment of the present invention.

For a description of pred_mode_flag and pred_mode_ibc_flag of FIG. 29, reference may be made to FIGS. 27 to 28. The embodiment of FIG. 29 may be for solving the problem described in FIG. 28.

According to an embodiment of the present invention, it is possible for CuPredMode to be inferred based on cu_skip_flag. Also, it is possible to infer CuPredMode based on which tile group it is. For example, in the case of an I tile group, it is possible to infer CuPredMode based on cu_skip_flag. For example, if it is an I tile group and cu_skip_flag is 0, it is possible to infer CuPredMode to MODE_INTRA. In addition, when it is an I tile group and cu_skip_flag is 1, it is possible to infer CuPredMode to MODE_IBC. Also, when cu_skip_flag is 0 and 1, it may indicate that the skip mode is not used and that the skip mode is used, respectively. Also, the above embodiments may be performed when pred_mode_flag or pred_mode_ibc_flag does not exist.

In addition, at this time, it is possible to set the CuPredMode based on cu_skip_flag without a process of setting it to another value. In addition, at this time, it is possible to set to MODE_IBC or MODE_INTRA without the process of setting CuPredMode to another value based on cu_skip_flag. For example, if it is an I tile group and cu_skip_flag is 1, it is possible to set CuPredMode to MODE_IBC immediately. Also, if it is an I tile group and cu_skip_flag is 0, it is possible to set CuPredMode to MODE_INTRA immediately. Similarly, the above embodiments may be performed when pred_mode_flag or pred_mode_ibc_flag does not exist.

In addition, there may be a CuPredMode infer value set based on the type of tile group and cu_skip_flag, and there may be a CuPredMode infer value set based on the type of tile group and not based on cu_skip_flag. For example, CuPredMode may be inferred to MODE_INTRA and MODE_IBC based on the type of tile group and cu_skip_flag. Also, based on the type of tile group, CuPredMode may be inferred to MODE_INTER.

Existing intra prediction other than IBC may not use the skip mode. Therefore, when it is signaled that the skip mode is used, it can be determined to be IBC or inter prediction. In addition, in the case of a tile group that is signaled to use skip mode and uses only intra prediction (including IBC), it can be determined to be IBC.

Referring to FIG. 29, when pred_mode_flag does not exist, CuPredMode may be inferred. If it is an I tile group and cu_skip_flag is 0, it can infer to MODE_INTRA. If it is an I tile group and cu_skip_flag is 1, it can infer to MODE_IBC. If it is a P tile group or B tile group, it can be inferred with MODE_INTER.

Also, referring to FIG. 29, when pred_mode_ibc_flag does not exist, CuPredMode may be inferred. If it is an I tile group and cu_skip_flag is 0, it can infer to MODE_INTRA. If it is an I tile group and cu_skip_flag is 1, it can infer to MODE_IBC. If it is a P tile group or B tile group, it can be inferred with MODE_INTER.

30 is a diagram illustrating prediction mode signaling according to an embodiment of the present invention.

For a description of pred_mode_flag and pred_mode_ibc_flag of FIG. 30, refer to FIGS. 27 to 28. The embodiment of FIG. 30 may be for solving the problem described in FIG. 28.

In an embodiment, a method of inferring CuPredMode or pred_mode_flag or pred_mode_ibc_flag may be different based on sps_ibc_enabled_flag.

In an embodiment, when sps_ibc_enabled_flag is 1, it is possible to use the infer method described in FIG. 29. In addition, when sps_ibc_enabled_flag is 0, it is possible to use the infer method described in FIG. 28.

Referring to FIG. 30, there may be a case in which a CuPredMode value is inferred. For example, when pred_mode_flag or pred_mode_ibc_flag does not exist, it is possible to infer the CuPredMode value. According to an embodiment of the present invention, when sps_ibc_enabled_flag is 1 or I tile group, CuPredMode may be inferred based on a cu_skip_flag value. For example, when sps_ibc_enabled_flag is 1, if it is an I tile group and cu_skip_flag is 0, CuPredMode may be set to MODE_INTRA. In addition, when sps_ibc_enabled_flag is 1, when it is an I tile group and cu_skip_flag is 1, CuPredMode may be set to MODE_IBC. In addition, when sps_ibc_enabled_flag is 1, CuPredMode may be set to MODE_INTER when it is a P tile group or a B tile group. In addition, when sps_ibc_enabled_flag is 0, and when it is an I tile group, CuPredMode may be set to MODE_INTRA. In addition, when sps_ibc_enabled_flag is 0, CuPredMode may be set to MODE_INTER when it is a P tile group or a B tile group.

31 is a diagram showing a coding unit syntax according to an embodiment of the present invention.

According to an embodiment of the present invention, in the case of an I tile group, pred_mode_ibc_flag may be parsed. In this case, the problem described in FIG. 28 can be solved. Also, if it is an I tile group and sps_ibc_enabled_flag is 1, pred_mode_ibc_flag may be parsed. That is, even when IBC mode is used in the I tile group and skip mode is used, pred_mode_ibc_flag may be set to indicate MODE_IBC.

Referring to FIG. 31, when (tile_group_type == I), sps_ibc_enabled_flag is 1, and when a condition related to block size is satisfied, pred_mode_ibc_flag is parsed.

32 is a diagram illustrating prediction mode signaling according to an embodiment of the present invention.

According to an embodiment of the present invention, when pred_mode_flag does not exist, pred_mode_flag may be inferred. In an embodiment, pred_mode_flag may be inferred based on the type of tile group. For example, in the case of an I tile group, the pred_mode_flag value may be inferred to 1. In addition, in the case of the P tile group, the pred_mode_flag value may be inferred to 0. Also, in the case of the B tile group, the pred_mode_flag value may be inferred to 0.

Also, CuPredMode may be set to MODE_INTER or MODE_INTRA based on pred_mode_flag. For example, when pred_mode_flag is 0, CuPredMode may be set to MODE_INTER. In addition, when pred_mode_flag is 1, CuPredMode may be set to MODE_INTRA.

According to an embodiment of the present invention, it is possible to set CuPredMode based on pred_mode_flag or pred_mode_ibc_flag. For example, when pred_mode_ibc_flag is 0, it is possible to set CuPredMode based on pred_mode_flag as well. For example, when pred_mode_ibc_flag is 0, it is possible to set CuPredMode to MODE_INTER or MODE_INTRA based on pred_mode_flag as well. Alternatively, when pred_mode_ibc_flag is 0, it is possible to set CuPredMode to a value other than MODE_IBC based on pred_mode_flag as well. Referring to FIG. 32, when pred_mode_ibc_flag is 0 and pred_mode_flag is 0, CuPredMode may be set to MODE_INTER. In addition, when pred_mode_ibc_flag is 0 and pred_mode_flag is 1, CuPredMode may be set to MODE_INTRA.

According to an embodiment of the present invention, there may be a case where CuPredMode is set based only on pred_mode_ibc_flag. For example, when pred_mode_ibc_flag is 1, CuPredMode can be set without other flags. For example, when pred_mode_ibc_flag is 1, CuPredMode may be set to MODE_IBC.

According to an embodiment of the present invention, when pred_mode_ibc_flag does not exist, pred_mode_ibc_flag may be inferred. For example, the pred_mode_ibc_flag value may be inferred based on the type of the tile group. In addition, the pred_mode_ibc_flag value may be inferred based on the type of tile group and the condition of using the IBC mode. More specifically, in the case of the I tile group, the pred_mode_ibc_flag value may be inferred based on the IBC mode availability condition. For example, if it is an I tile group and satisfies the condition for enabling IBC use, the value of pred_mode_ibc_flag may be inferred to 1. When inferred to 1, CuPredMode may be set to a MODE_IBC value. In addition, if it is an I tile group and does not satisfy the conditions for enabling IBC use, the pred_mode_ibc_flag value may be inferred to 0. Alternatively, if it is an I tile group and does not satisfy at least one of the conditions for using IBC, the pred_mode_ibc_flag value may be inferred to 0. When inferred to 0, CuPredMode may be set to a value other than MODE_IBC. The IBC mode enablement condition may include a value of sps_ibc_enabled_flag. In addition, the conditions for enabling IBC mode may include conditions related to block size. Referring to FIG. 32, when I tile group and sps_ibc_enabled_flag is 1, it is possible to infer a value of pred_mode_ibc_flag to 1. At this time, when the IBC mode enablement condition is added and the condition is satisfied, it is possible to infer the pred_mode_ibc_flag value to 1. In Figure 32, the additional IBC mode usage condition is shown as a block size condition.

Also, if it is an I tile group (condition 1 in FIG. 32) and sps_ibc_enabled_flag is 0 (condition 2a in FIG. 32)), the pred_mode_ibc_flag value may be inferred to 0. In addition, if it is an I tile group (condition 1 in FIG. 32) and does not satisfy other IBC mode usage conditions (condition 2b in FIG. 32)), the pred_mode_ibc_flag value may be inferred to 0.

In another embodiment, in the case of a P or B tile group, a value of pred_mode_ibc_flag may be inferred to 0. In addition, in the case of a P or B tile group, the pred_mode_ibc_flag value may be inferred to a preset value without conditions other than the type of the tile group.

In a number of embodiments of the present invention, infer may mean setting, derivation, or the like.

According to an embodiment of the present invention, treeType may be derived as follows.

If tile_group_type is I and qtbtt_dual_tree_intra_flag is 1, treeType may be set to DUAL_TREE_LUMA. Alternatively, when tile_group_type is I, qtbtt_dual_tree_intra_flag is 1, and luma component is processed, treeType may be set to DUAL_TREE_LUMA.

If tile_group_type is I and qtbtt_dual_tree_intra_flag is 1, treeType may be set to DUAL_TREE_CHROMA. Alternatively, when tile_group_type is I and qtbtt_dual_tree_intra_flag is 1 and the chroma component is processed, the treeType may be set to DUAL_TREE_CHROMA.

If tile_group_type is not I or qtbtt_dual_tree_intra_flag is 0, treeType may be set to SINGLE_TREE.

According to an embodiment, qtbtt_dual_tree_intra_flag may be a signaling indicating whether a dual tree is allowed. Allowing the dual tree may mean that there is a separate coding quad tree syntax structure for luma and chroma components. More specifically, qtbtt_dual_tree_intra_flag may be signaling indicating whether a dual tree is allowed when the current picture is the only reference picture.

33 is a diagram illustrating a coding unit syntax according to an embodiment of the present invention.

According to an embodiment of the present invention, the IBC mode may not be used for the chroma component. More specifically, in the case of DUAL_TREE_CHROMA, the IBC mode may not be used.

Referring to FIG. 33, when treeType is not DUAL_TREE_CHROMA, pred_mode_ibc_flag may be parsed. In addition, when the treeType is DUAL_TREE_CHROMA, pred_mode_ibc_flag may not be parsed. According to an embodiment, when the treeType is DUAL_TREE_CHROMA, CuPredMode may be inferred to MODE_INTRA.

34 is a diagram showing a coding unit syntax according to an embodiment of the present invention.

The coding unit syntax of FIG. 34 may indicate syntax related to intra prediction. According to an embodiment of the present invention, intra_chroma_pred_mode signaling may exist. In addition, the intra prediction mode of the chroma component may be determined based on the intra_chroma_pred_mode.

Referring to FIG. 34, when the treeType is SINGLE_TREE or DUAL_TREE_CHROMA, it is possible to pars intra_chroma_pred_mode. Also, when the treeType is DUAL_TREE_LUMA, it is possible not to pars the intra_chroma_pred_mode.

35 is a diagram illustrating intra prediction mode derivation of a chroma component according to an embodiment of the present invention.

Referring to FIG. 35, IntraPredModeC may be an intra prediction mode for a chroma component. In addition, xCb and yCb may represent a top-left sample of a chroma coding block based on a luma location. In addition, IntraPredModeY may be an intra prediction mode for a luma component.

According to an embodiment of the present invention, IntraPredModeC may be determined based on IntraPredModeY. In addition, IntraPredModeC may be determined based on IntraPredModeY and intra_chroma_pred_mode. In this case, IntraPredModeY may be a mode corresponding to a luma block corresponding to a current chroma block. According to an embodiment, a location using IntraPredModeY corresponding to IntraPredModeC for a certain location may be preset. According to an embodiment, the preset position may be a luma block position corresponding to the center of the current chroma block. For example, when derivation of IntraPredModeC at position (xCb, yCb), IntraPredModeY at position (xCb + cbWidth/2, yCb + cbHeight/2) can be referenced. Alternatively, when derivation of IntraPredModeC at the (xCb, yCb) position, the preset position may be a position based on xCb or yCb.

The IntraPredModeC value for a certain IntraPredModeY value may refer to Table 8-2 or Table 8-3 of FIG. 35. Table 8-2 may correspond to a case where CCLM cannot be used (or sps_cclm_enalbed_flag is 0), and Table 8-3 may correspond to a case where CCLM is available (or sps_cclm_enalbed_flag is 1). When IntraPredModeY is a value, a column corresponding to the value may be referred to in FIG. 35, and a value corresponding to intra_chroma_pred_mode in the column may be IntraPredModeC. For example, when IntraPredModeY is 1 and intra_chroma_pred_mode is 1, IntraPredModeC may be 50.

According to an embodiment, sps_cclm_enalbed_flag may be a higher level signaling indicating whether CCLM can be applied. For example, when sps_cclm_enalbed_flag is 1, CCLM may be applied. In addition, when sps_cclm_enalbed_flag is 0, CCLM may not be applied.

If the IntraPredModeC value of FIG. 35 is 81, 82, or 83, it may correspond to the CCLM mode. In addition, when sps_cclm_enabled_flag of FIG. 35 is 0, an IntraPredModeC value of 4 may correspond to a DM mode. In addition, when sps_cclm_enabled_flag of FIG. 35 is 1, an IntraPredModeC value of 7 may correspond to a DM mode.

Also, there may be a bin string definition signaling intra_chroma_pred_mode. For example, the DM mode can be expressed by using the intra_chroma_pred_mode with the smallest number of bits. For example, the DM mode can be expressed using 1-bit intra_chroma_pred_mode.

According to an embodiment, when sps_cclm_enalbed_flag is 0, the number of bits representing intra_chroma_pred_mode values 4, 0, 1, 2, and 3 may increase or be the same. According to an embodiment, when sps_cclm_enalbed_flag is 0, bin strings representing intra_chroma_pred_mode values 4, 0, 1, 2, and 3 may be 0, 100, 101, 110, 111, respectively.

According to an embodiment, when sps_cclm_enalbed_flag is 1, the number of bits representing intra_chroma_pred_mode values 7, 4, 5, 6, 0, 1, 2, 3 may be gradually increased or equal. According to an embodiment, when sps_cclm_enalbed_flag is 1, bin strings representing intra_chroma_pred_mode values 7, 4, 5, 6, 0, 1, 2, 3 are 0, 10, 1110, 1111, 11000, 11001, 11010, 11011, respectively. I can.

However, according to the described embodiments, a case in which intra prediction of a chroma block is not easy may occur. In particular, there may be cases where intra prediction mode derivation for a chroma block is not easy. As described above, when the chroma block is intra prediction, it may be necessary to refer to the intra prediction mode for the corresponding luma block in order to determine the intra prediction mode. However, if the corresponding luma location does not perform intra prediction, or if it is not MODE_INTRA, it may occur. For example, when the corresponding luma location is MODE_IBC, the corresponding luma intra prediction mode may not exist. According to an embodiment, in the case of SINGLE_TREE, it is possible for a corresponding luma block and a chroma block to use the same prediction mode. In addition, in the case of DUAL_TREE, it is possible to use different prediction modes for the corresponding luma block and chroma block. Also, it is possible to use DUAL_TREE in the case of I tile group. In addition, it is possible to use MODE_INTRA or MODE_IBC in the case of I tile group. Therefore, it may happen that DUAL_TREE_LUMA uses MODE_IBC and DUAL_TREE_CHROMA uses MODE_INTRA at the same location.

36 is a diagram illustrating intra prediction mode derivation of a chroma component according to an embodiment of the present invention.

The embodiment of FIG. 36 may be a method for solving the problem described in FIG. 35.

According to an embodiment of the present invention, if IntraPredModeY does not exist, IntraPredModeY may be set to a preset mode (or value). Therefore, it is possible to derive IntraPredModeC even when the luma position corresponding to the chroma block does not use intra prediction or when the IBC mode is used.

More specifically, when IntraPredModeY does not exist, it is possible to set IntraPredModeY to planar mode (value 0). In this case, in the signaling method described with reference to FIG. 35, it is possible to signal the planar mode using a small number of bits.

Alternatively, if IntraPredModeY does not exist, it is possible to set IntraPredModeY to DC mode (value 1). In this case, in the signaling method described with reference to FIG. 35, it is possible to signal the DC mode using a small number of bits.

Alternatively, when IntraPredModeY does not exist, it is possible to set IntraPredModeY to vertical mode (value 50). In this case, it is possible to signal using a small number of bits in the vertical mode in the signaling method described in FIG. 35.

Alternatively, when IntraPredModeY does not exist, it is possible to set IntraPredModeY to horizontal mode (value 18). In this case, in the signaling method described with reference to FIG. 35, it is possible to signal the horizontal mode using a small number of bits.

In another embodiment, when IntraPredModeY does not exist, IntraPredModeC values corresponding to intra_chroma_pred_mode values may be set to values not shown in FIG. 35. That is, in FIG. 35, a column may exist separately when the IntraPredModeY value does not exist. For example, IntraPredModeC corresponding to intra_chroma_pred_mode 4, 0, 1, 2, and 3 may be 0, 1, 50, and 18, respectively. Alternatively, IntraPredModeC corresponding to intra_chroma_pred_mode 4, 0, 1, 2, and 3 may be 0, 50, 18, and 1, respectively. This can be applied to both the case where sps_cclm_enabled_flag is 0 and 1.

In another embodiment, when IntraPredModeY does not exist, it is possible to set IntraPredModeC to a preset value. For example, when IntraPredModeY does not exist, it is possible to set IntraPredModeC to a preset value regardless of intra_chroma_pred_mode. In addition, when IntraPredModeY does not exist, it is possible to signal the intra_chroma_pred_mode value to 0 at all times. For example, if IntraPredModeY does not exist, it is possible to set IntraPredModeC to planar mode. Alternatively, if IntraPredModeY does not exist, it is possible to set IntraPredModeC to CCLM. Alternatively, if IntraPredModeY does not exist, it is possible to set IntraPredModeC to DM mode. In addition, when IntraPredModeY does not exist, it is possible not to pars the intra_chroma_pred_mode described in FIG. 34.

In another embodiment, when IntraPredModeY does not exist, it is possible to change a position referring to IntraPredModeY.

In the above embodiments, when IntraPredModeY does not exist, it may mean that it is not the corresponding luma position MODE_INTRA referred to when derivation of the chroma intra prediction mode. Or, when derivation of the chroma intra prediction mode at the (xCb, yCb) position, it means that CuPredMode[ xCb + cbWidth/2][ yCb + cbHeight/2] corresponding to the luma component is not MODE_INTRA or is MODE_IBC. It is possible.

Alternatively, it is possible to mean that IntraPredModeY[xCb + cbWidth/2][ yCb + cbHeight/2] corresponding to the luma component does not exist when derivation of the chroma intra prediction mode at the (xCb, yCb) position.

Referring to FIG. 36, when IntraPredModeC[xCb][yCb] is derived, if IntraPredModeY[xCb + cbWidth/2][yCb + cbHeight/2] does not exist, IntraPredModeY[xCb + cbWidth/2][ yCb + cbHeight/2] Can be set to a preset value. In addition, IntraPredModeC may be derived with reference to IntraPredModeY[xCb + cbWidth/2][yCb + cbHeight/2] and the table described in FIG. 35.

Also, when IntraPredModeY[ xCb + cbWidth / 2 ][ yCb + cbHeight / 2] exists when derive IntraPredModeC[ xCb ][ yCb ], IntraPredModeY[ xCb + cbWidth / 2 ][ yCb + cbHeight / 2] and Fig. 35 IntraPredModeC can be derived by referring to the table described above.

According to an embodiment of the present invention, when a corresponding luma block uses an IBC mode when predicting a chroma block, the prediction mode may be limited. More specifically, when intra prediction of a chroma block, the intra prediction mode may be limited when the corresponding luma block uses the IBC mode. In this case, for example, it is possible not to use the DM mode. This is because if the corresponding luma block and chroma block use different modes, the similarity between the two may be inferior.

37 is a diagram showing a coding unit syntax according to an embodiment of the present invention.

According to an embodiment of the present invention, motion information for a chroma block may exist separately from motion information for a luma block. For example, when the chroma block uses the IBC mode, motion information for the chroma block may exist separately from motion information for the luma block.

Referring to FIG. 37, when the treeType is DUAL_TREE_CHROMA, it is possible to pars the syntax element related to motion information. For example, when treeType is DUAL_TREE_CHROMA and CuPredMode is MODE_IBC, it is possible to pars the syntax element related to motion information. The motion information related syntax element may include a merge_flag, a syntax element in merge_data, mvp_l0_flag, amvr_4pel_flag, and the like.

38 is a diagram showing a syntax structure according to an embodiment of the present invention.

According to an embodiment of the present invention, a prediction mode may be limited based on a block size. That is, CuPredMode may be limited based on the block size. For example, inter prediction may be limited. This could be to lower the memory bandwidth or computational complexity. For example, the prediction mode may be limited in blocks of small size. For example, the prediction mode may be limited in blocks of sizes less than the threshold. For example, the threshold may be 4x4 size. That is, in a specific embodiment, inter prediction may not be used in a block having a size of 4x4 or less.

The limited prediction mode described as another embodiment may be bi-prediction inter prediction. For example, bi-prediction may not be used in a block size below a threshold. In this case, the threshold may represent 4x8 or 8x4 or less. For example, the threshold (width + height) may be 12. If bi-prediction is restricted, it is possible that a process of converting bi-prediction to uni-prediction exists. Alternatively, when bi-prediction is limited, a value indicating a prediction direction or a reference list to be used may be limited.

As described above, the prediction mode may be limited, and accordingly, a syntax structure different from that described in the preceding drawings may be used for efficient signaling.

According to an embodiment of the present invention, in the case of MODE_INTRA, the skip mode may not be used. Therefore, in the case of MODE_INTRA, cu_skip_flag may be 0. Therefore, if cu_skip_flag is 1, it can be determined that it is not MODE_INTRA.

Referring to FIG. 38, when the tile group type is not I or sps_ibc_enabled_flag is 1, it is possible to pars cu_skip_flag, pred_mode_flag, and pred_mode_ibc_flag. Also, at this time, parsing can be performed by considering additional conditions. That is, when the tile group type is I and sps_ibc_enabled_flag is 0, cu_skip_flag, pred_mode_flag, and pred_mode_ibc_flag may not be parsed. According to an embodiment, CuPredMode may be one of MODE_INTRA, MODE_INTER, and MODE_IBC. If the tile group type is I, a possible CuPredMode value may be MODE_INTRA or MODE_IBC. However, when MODE_IBC is limited, for example, when sps_ibc_enalbed_flag is 0, the only possible CuPredMode value may be MODE_INTRA. Therefore, when the tile group type is I and sps_ibc_enabled_flag is 0, pred_mode_flag and pred_mode_ibc_flag are not parsed, and CuPredMode can be determined as MODE_INTRA. Also, as described above, cu_skip_flag may be determined as 0.

According to an embodiment of the present invention, cu_skip_flag, pred_mode_flag, and pred_mode_ibc_flag may be parsed based on the block size.

For example, if inter prediction is a block size for which inter prediction is limited, and if IBC cannot be used, cu_skip_flag may not be parsed. In other words, it is possible to pars the cu_skip_flag when the block size that can use inter prediction or when the IBC can be used. If the inter prediction is a limited block size and IBC cannot be used, CuPredMode may be determined as MODE_INTRA. In this case, the cu_skip_flag value may be determined as 0 and inferred. In an embodiment, the block size for which inter prediction is limited may be a 4x4 block. In addition, when the IBC is not available, sps_ibc_enabled_flag may be 0.

According to an embodiment of the present invention, if the inter prediction is a limited block size, pred_mode_flag may not be parsed. According to an embodiment of the present invention, it is possible to determine whether CuPredMode is MODE_INTRA or MODE_INTER based on the value of pred_mode_flag. If the inter prediction is a limited block size, it may be determined that pred_mode_flag is a value in which CuPredMode represents MODE_INTRA. Also, CuPredMode may be changed based on pred_mode_ibc_flag. That is, CuPredMode may be determined based on pred_mode_flag and pred_mode_ibc_flag, and CuPredMode determined based only on pred_mode_flag may be changed based on pred_mode_ibc_flag. According to an embodiment, it may be determined whether CuPredMode is MODE_IBC or a value determined based only on pred_mode_flag according to the pred_mode_ibc_flag value.

If the inter prediction is an unrestricted block size, it is possible to pars the pred_mode_flag. At this time, additional conditions can be considered. For example, whether to parsing pred_mode_flag may be determined based on cu_skip_flag or tile group type. As described, pred_mode_flag may be a value that determines whether CuPredMode is MODE_INTRA or MODE_INTER, because CuPredMode may be restricted based on cu_skip_flag or tile group type. For example, when the tile group type is I, only the value of MODE_INTRA for CuPredMode may be possible. In addition, when the tile group type is not I, that is, when the tile group type is P or B, CuPredMode may be both MODE_INTRA and MODE_INTER. However, if the tile group type is not I, and cu_skip_flag is 1, only the value of MODE_INTER for CuPredMode may be possible. Therefore, according to an embodiment of the present invention, when cu_skip_flag is 1 or tile group type is I, pred_mode_flag may not be parsed. Accordingly, according to an embodiment of the present invention, when the tile group type is I, pred_mode_flag or CuPredMode may be inferred to a value indicating MODE_INTRA. In addition, when the tile group type is P or B, pred_mode_flag or CuPredMode may be inferred to a value indicating MODE_INTER.

In an embodiment, the block size for which inter prediction is limited may be a 4x4 block. Alternatively, the block size for which inter prediction is limited may be a block of 4x4 or less.

In addition, pred_mode_ibc_flag may be parsed based on the block size in which inter prediction is limited. In addition, pred_mode_ibc_flag may be parsed based on cu_skip_flag. According to an embodiment, when the inter prediction is a block size that is limited and cu_skip_flag is 1, pred_mode_ibc_flag may not be parsed. As described above, in a block size where inter prediction is limited, CuPredMode may not be MODE_INTER. In addition, when cu_skip_flag is 1, CuPredMode may not be MODE_IBC. Therefore, if the inter prediction is a block size that is limited, and cu_skip_flag is 1, pred_mode_ibc_flag or CuPredMode may be determined as MODE_IBC and inferred. Also, this may be a case where setting with MODE_IBC is possible. For example, when sps_ibc_enabled_flag is 1, it may be possible to set it to MODE_IBC. Therefore, when the inter prediction is a block size that is limited, and cu_skip_flag is 1, pred_mode_ibc_flag or CuPredMode may be determined and inferred according to sps_ibc_enabled_flag. More specifically, when the inter prediction is a block size limited, and cu_skip_flag is 1, pred_mode_ibc_flag may be inferred to sps_ibc_enabled_flag. In addition, it is possible to pars pred_mode_ibc_flag when inter prediction is an unrestricted block size or cu_skip_flag is 0.

Also, when the tile group type is I and cu_skip_flag is 1, it is possible not to pars the pred_mode_ibc_flag. In addition, at this time, it is possible to determine and infer pred_mode_ibc_flag or CuPredMode as a value indicating MODE_IBC. The possible CuPredMode values in the I tile group are MODE_INTRA and MODE_IBC, but it may be because skip mode is not used when it is MODE_INTRA. Therefore, when the tile group type is I and cu_skip_flag is 0, it is possible to pars the pred_mode_ibc_flag.

In addition, when the tile group type is not I, the CuPredMode is MODE_INTRA, and the pred_mode_ibc_flag may not be parsed when the inter prediction is not a limited block size. In this case, it may be because the prediction mode can be determined without pred_mode_ibc_flag. In addition, when the tile group type is not I, when CuPredMode is not MODE_INTRA or is a block size in which inter prediction is limited, pred_mode_ibc_flag may be parsed. Also, in this case, pred_mode_ibc_flag may be parsed in consideration of additional conditions. For example, when the tile group type is not I, when the CuPredMode is MODE_INTRA, the pred_mode_ibc_flag can be parsed when the inter prediction is a block. This is because even if the inter prediction is limited, the final prediction mode can be determined as MODE_INTRA or MODE_IBC. In this case, it is possible to additionally pars pred_mode_ibc_flag when cu_skip_flag is 0.

In an embodiment, the block size for which inter prediction is limited may be a 4x4 block. Alternatively, the block size for which inter prediction is limited may be a block of 4x4 or less.

39 is a diagram illustrating a signaling value infer method according to an embodiment of the present invention.

Referring to FIG. 39, as described in FIG. 38, pred_mode_flag or pred_mode_ibc_flag may be inferred. Alternatively, as described with reference to FIG. 38, CuPredMode may be determined. In addition, pred_mode_flag and pred_mode_ibc_flag of FIG. 39 may be the same signaling as pred_mode_flag and pred_mode_ibc_flag of FIG. 38, respectively.

According to an embodiment of the present invention, CuPredMode may be determined as MODE_INTER or MODE_INTRA based on a value of pred_mode_flag. If this value is called MODE_TEMP, CuPredMode may be determined as MODE_TEMP or MODE_IBC based on the value of pred_mode_ibc_flag.

As described in FIG. 38, in the case of a block size in which inter prediction is limited, pred_mode_flag may be inferred to a value indicating MODE_INTRA. That is, when the inter prediction is a limited block size, pred_mode_flag may be inferred to 1. Referring to FIG. 39, when the block size is 4x4, a value of pred_mode_flag may be inferred to 1.

In addition, as described with reference to FIG. 38, in the case of a block size in which inter prediction is limited, and in skip mode, pred_mode_ibc_flag may be inferred to a value indicating MODE_IBC. This may be the case where it is possible to use MODE_IBC. For example, it is possible to use MODE_IBC when sps_ibc_enabled_flag is 1. For example, in the case of a block size in which inter prediction is limited, and in skip mode, pred_mode_ibc_flag may be inferred as sps_ibc_enabled_flag value. Referring to FIG. 39, when the block size is 4x4 and in skip mode, pred_mode_ibc_flag may be inferred as sps_ibc_enabled_flag value.

40 is a diagram illustrating a signaling value infer method according to an embodiment of the present invention.

In FIGS. 38 to 39, a method of parsing, infering, or determining cu_skip_flag, pred_mode_flag, pred_mode_ibc_flag, and CuPredMode has been described. However, there may be a conflict in the infer method shown in FIG. 39.

For example, when inter prediction is a limited block size and a tile group type is P or B, it may be difficult to infer a value of pred_mode_flag. In FIG. 39, the pred_mode_flag value may be inferred to one of two values, and both cases may be satisfied.

In addition, it may be difficult to infer a pred_mode_ibc_flag value when inter prediction is a limited block size, skip mode, and tile group type P or B. In FIG. 39, the pred_mode_ibc_flag value may be inferred to one of two values, and both cases may be satisfied.

40 may be an embodiment for solving this problem.

When the tile group type is P or B, possible prediction modes are MODE_INTRA, MODE_INTER, and MODE_IBC. In this case, if the inter prediction is a limited block size, MODE_INTER among MODE_INTRA, MODE_INTER, and MODE_IBC may not be used. Therefore, according to an embodiment of the present invention, in this case, it is possible to infer pred_mode_flag to a value indicating MODE_INTRA. This is because it is possible to determine MODE_IBC through pred_mode_ibc_flag. Therefore, it can be summarized as follows.

If the tile group type is I or the block size for which inter prediction is limited, pred_mode_flag may be inferred to a value indicating MODE_INTRA. In addition, when 1) tile group type is P or B, and 2) inter prediction is not a limited block size, pred_mode_flag may be inferred to a value indicating MODE_INTER.

When the tile group type is P or B, possible prediction modes are MODE_INTRA, MODE_INTER, and MODE_IBC. In this case, if the inter prediction is a limited block size, MODE_INTER among MODE_INTRA, MODE_INTER, and MODE_IBC may not be used. Also, in the case of skip mode, MODE_INTRA among MODE_INTRA, MODE_INTER, and MODE_IBC may not be used. Therefore, when the tile group type is P or B, the block size in which inter prediction is limited, and in the skip mode, only MODE_IBC can be used. Therefore, in this case, it is possible to infer pred_mode_ibc_flag to 1. Therefore, it can be summarized as follows.

If 1) tile group type is I or 2) inter prediction is limited block size and is in skip mode, pred_mode_ibc_flag may be inferred to a value indicating MODE_IBC, for example, 1. In addition, when i) tile group type is P or B and ii) inter prediction is not restricted block size or is not in skip mode, pred_mode_ibc_flag may be inferred to a value that does not indicate MODE_IBC, for example, 0.

In an embodiment, the block size for which inter prediction is limited may be a 4x4 block. Alternatively, the block size for which inter prediction is limited may be a block of 4x4 or less.

FIG. 40 shows an example of the pred_mode_flag and pred_mode_ibc_flag infer methods described in the case where the block size in which inter prediction is limited is 4x4.

In addition, in the described inventions, the tile group type may be a slice type.

Also, whether the skip mode is performed may be determined through cu_skip_flag.

41 is a diagram illustrating an inter_pred_idc value and binarization according to an embodiment of the present invention.

As described in FIG. 38, bi-prediction may not be used based on the block size. Therefore, according to an embodiment of the present invention, possible inter prediction in a certain block size may be L0 uni-prediction, L1 uni-prediction, and bi-prediction, and in certain block sizes, possible inter prediction is L0 uni-prediction, L1 uni- It can be prediction. In addition, it is possible to indicate which inter prediction is through inter_pred_idc. Also, the L0 uni-prediction may be an inter prediction using only reference list 0. Also, the L1 uni-prediction may be an inter prediction using only reference list 1. Also, the bi-prediction may be an inter prediction using both reference list 0 and reference list 1. Also, it is possible to determine which inter prediction is for each CU. In addition, inter_pred_idc values representing L0 uni-prediction, L1 uni-prediction, and bi-prediction may be PRED_L0, PRED_L1, and PRED_BI, respectively. In addition, inter_pred_idc values representing L0 uni-prediction, L1 uni-prediction, and bi-prediction may be 0, 1, and 2, respectively.

According to an embodiment of the present invention, in the case of a block size in which bi-prediction is not used, an inter_pred_idc value corresponding to bi-prediction may not exist.

In addition, there may be a binarization method to indicate inter_pred_idc. In addition, this method may be different for blocks in which bi-prediction is allowed and blocks that are not allowed. Also, this may be a bin string used when parsing inter_pred_idc. If bi-prediction is allowed, values corresponding to L0 uni-prediction or L1 uni-prediction or bi-prediction may be possible as inter_pred_idc. To indicate this, inter_pred_idc can be expressed in a variable length binarization method. For example, values corresponding to L0 uni-prediction, L1 uni-prediction, and bi-prediction may be represented as 00, 01, and 1, respectively. Alternatively, values corresponding to L0 uni-prediction, L1 uni-prediction, and bi-prediction may be represented as 10, 11, and 0, respectively. In addition, if bi-prediction is not allowed, values corresponding to L0 uni-prediction or L1 uni-prediction may be possible as inter_pred_idc. Therefore, inter_pred_idc can be expressed as 1-bit. For example, values corresponding to L0 uni-prediction and L1 uni-prediction may be represented as 0 and 1, respectively. Alternatively, values corresponding to L0 uni-prediction and L1 uni-prediction may be represented as 1 and 0, respectively.

According to an embodiment, a block size in which bi-prediction is not used may be a block size below a threshold. For example, the threshold may be a 4x8 block or an 8x4 block. If 4x4 inter prediction is not allowed, the block size for which bi-prediction is not used may be a 4x8 or 8x4 block. Also, a 4x4 block can be expressed as (width + height == 8). Also, a 4x8 or 8x4 block can be expressed as (width + height == 12).

Referring to FIG. 41, in the case of a 4x8 or 8x4 block, only values corresponding to PRED_L0 and PRED_L1 may exist for inter_pred_idc. Also, in this case, inter_pred_idc may be represented as 0 or 1.

42 is a diagram illustrating an inter_pred_idc value and binarization according to an embodiment of the present invention.

As described in FIG. 41, there may be a number of sets of values that can be represented by inter_pred_idc and signaling methods thereof. For example, in some blocks, there are three types of values that can be represented by inter_pred_idc, and in this case, signaling can be performed using 1 to 2 bits. In addition, in some blocks, there are two types of values that can be represented by inter_pred_idc, and signaling can be performed using b-bits. In addition, at this time, the types and signaling of values that can be represented by inter_pred_idc may be changed based on the block size. For example, depending on whether or not bi-prediction is an allowable block size, it is possible that the types and signaling of values that can be represented by inter_pred_idc are different.

However, in the method described with reference to FIG. 41, there may be a case where there is an ambiguity in signaling and types of values that can be represented by inter_pred_idc in a certain block size. For example, if the block size is 4x8 or 8x4, both conditions (width + height) !=8 and ((width+height == 8) || (width+height == 12)) can be satisfied. Therefore, a case in which signaling and bitstreams between encoders and decoders are inconsistent may occur.

The embodiment of FIG. 42 may be a method for solving this problem. According to an embodiment of the present invention, when condition1 is satisfied and when !condition1 is satisfied, a type of a value that can be indicated by inter_pred_idc and a signaling method may be different. For example, condition1 may be a block size condition in which bi-prediction is not allowed. For example, condition1 may be a 4x8 or 8x4 block condition. If bi-prediction is not allowed and inter_pred_idc is signaled using 2 bits, signaling may not be efficient. This is because PRED_BI will not be indicated as an inter_pred_idc value when bi-prediction is not allowed. In an embodiment, a block size condition in which bi-prediction is not allowed may be a block size of 4x8 or 8x4 or less. Therefore, the block size for which bi-prediction is not allowed may be 4x8 or 8x4 or 4x4.

Referring to FIG. 42, when width + height is 8 or 12, possible values for inter_pred_idc may be PRED_L0 and PRED_L1. Also, at this time, inter_pred_idc may be indicated through 1-bit. Signaling can be 0 or 1. In addition, when width + height is not 8 and not 12, possible values for inter_pred_idc may be PRED_L0, PRED_L1, and PRED_BI. Also, at this time, inter_pred_idc may be indicated through 1- or 2-bit. The signaling may be 00, 01, or 1.

43 is a diagram illustrating an inter_pred_idc value and binarization according to an embodiment of the present invention.

43 may be an embodiment for solving the problem described in FIGS. 41 to 42. Also, FIG. 43 may be a method of increasing efficiency in the embodiment of FIG. 42. As described above, there may be a block size in which inter prediction is not allowed. In the embodiment of FIG. 42, if the block size in which inter prediction is not allowed is not considered, unnecessary condition check may be required. For example, when inter prediction is not allowed, the inter_pred_idc value may have no meaning. However, this may be meaningless if the condition in the case where inter prediction is not allowed in inter_pred_idc signaling is checked. Accordingly, according to an embodiment of the present invention, inter_pred_idc signaling and a set of values may be determined by performing a condition check in a case in which bi-prediction is not allowed without a condition check in a case in which inter prediction is not allowed. For example, when inter prediction is not allowed, it may be a 4x4 block size, and when bi-prediciton is not allowed, it may be a 4x8 or 8x4 block size.

Referring to FIG. 43, when width + height is 12, possible values for inter_pred_idc may be PRED_L0 and PRED_L1. Also, at this time, inter_pred_idc may be indicated through 1-bit. Signaling can be 0 or 1. In addition, when width + height is not 12, possible values for inter_pred_idc may be PRED_L0, PRED_L1, and PRED_BI. Also, at this time, inter_pred_idc may be indicated through 1- or 2-bit. The signaling may be 00, 01, or 1.

Therefore, in fact, in the case of a 4x4 block in the embodiment of FIG. 43, the inter_pred_idc value set and signaling correspond to the left of the two columns of FIG. 43 (the third column in all), which may be different from the embodiment of FIG. have.

According to an embodiment of the present invention, when the treeType is DUAL_TREE_CHROMA, it may be possible to pars the cu_skip_flag. When the treeType is DUAL_TREE_CHROMA, it may indicate that partitioning of a luma block and a chroma block may be different, and processing corresponding to chroma. In addition, when the treeType is DUAL_TREE_CHROMA, it may be possible to pars cu_skip_flag when it is possible to use MODE_IBC. When it is possible to use MODE_IBC, it may be a case where sps_ibc_enabled_flag is 1. This may be to enable the use of skip mode when the prediction mode of the chroma block is MODE_IBC.

44 is a diagram showing a coding unit syntax structure according to an embodiment of the present invention.

The syntax elements shown in FIG. 44 may be syntax elements described in the previous drawings, and redundant descriptions may be omitted. In addition, the present invention may include the parts described in FIG. 27.

As described above, there may be multiple prediction modes. For example, the plurality of prediction modes may include MODE_INTRA, MODE_IBC, and MODE_INTER. Referring to FIG. 44, the prediction mode may be represented by CuPredMode. Also, there may be MODE_INTRA and MODE_IBC as prediction modes that refer only to the current picture. In addition, MODE_IBC may indicate a block to be referred to for prediction by using a block vector or motion vector or motion information. Also, MODE_INTER can refer to another picture. Also, the prediction mode used may be limited depending on the type of slice and tile group. For example, the type of slice and the type of tile group may be represented by slice_type, tile_group_type, and the like. In the following description, what is written as slice_type can also be applied to tile_group_type. In addition, if slice_type is X, it may be X slice. In addition, when the tile_group_type is X, it may be an X tile group. Also, I slice may use MODE_INTRA or MODE_IBC, and I slice may not use MODE_INTER.

According to an embodiment of the present invention, in the case of MODE_INTRA, the skip mode may not be used. That is, in the case of MODE_INTRA, the cu_skip_flag value may always be the same value. For example, in the case of MODE_INTRA, the cu_skip_flag value may always be 0. On the contrary, it may not be MODE_INTRA when it is indicated to use skip mode. That is, the prediction mode may be determined based on the cu_skip_flag value, and for example, it may be determined whether the prediction mode is (MODE_INTRA, MODE_INTER, or MODE_IBC) or (MODE_INTER, or MODE_IBC) based on the cu_skip_flag value.

According to an embodiment of the present invention, the prediction mode may be determined based on cu_skip_flag, pred_mode_flag, and pred_mode_ibc_flag. For example, pred_mode_ibc_flag may be a signaling indicating whether or not it is MODE_IBC. For example, if the pred_mode_ibc_flag value is 1, CuPredMode may be MODE_IBC, and if the pred_mode_ibc_flag value is 0, CuPredMode may be MODE_INTRA or MODE_INTER. This will be further described in FIG. 45.

According to an embodiment of the present invention, a prediction mode may be limited based on a block size. In an embodiment, MODE_INTER may not be used based on the block size. For example, as described above, MODE_INTER may not be used for a small block size. For example, if the block size is 4x4, MODE_INTER may not be used. Therefore, only MODE_INTRA or MODE_IBC can be used for a block of this size. Accordingly, as described above, if MODE_INTER is a block size that cannot be used and MODE_IBC cannot be used, cu_skip_flag is not parsed, and the value may be inferred to a value indicating that skip mode is not used, for example, 0. The case where MODE_IBC cannot be used may include a case indicating that the IBC cannot be used by higher level signaling. Referring to FIG. 44, high-level signaling indicating whether or not IBC can be used may be sps_ibc_enabled_flag, and when IBC is not available, a value of sps_ibc_enabled_flag may be 0. In addition, in the case of a block size in which MODE_INTER cannot be used, pred_mode_flag is not parsed, and the value can be inferred to a value indicating MODE_INTRA, for example, 1. In addition, in the case of a block size in which MODE_INTER cannot be used, the pred_mode_ibc_flag is not parsed when the skip mode is used, and the value can be inferred to a value indicating the use of MODE_IBC, for example 1.

In another embodiment, MODE_IBC may not be used based on the block size. Not using MODE_IBC may mean that a signaling indicating whether MODE_IBC is used (eg, pred_mode_ibc_flag) is a preset value (eg, 0) indicating that MODE_IBC is not used. Also, not using MODE_IBC may mean that signaling indicating whether MODE_IBC is used is not parsed. For example, MODE_IBC may not be used for a large block size. For example, MODE_IBC may not be used for blocks with both width and height of 128 or more. Alternatively, for a block with both width and height 128, MODE_IBC may not be used, and it may not be possible to have a width or height greater than 128. Therefore, referring to FIG. 44, when width or height is not 128, pred_mode_ibc_flag can be parsed. Also, when both width and height are 128, pred_mode_ibc_flag may not be parsed. In addition, if both width and height are 128, pred_mode_ibc_flag can be inferred to 0.

The width and height of a block can be cbWidth and cbHeight, respectively, and this can be for a block that is a coding unit or a prediction unit.

Referring to FIG. 44, cu_skip_flag may be parsed when the block size is 128x128 or 128x128 or more. However, if the prediction mode is limited based on the block size, it is possible to perform more efficient signaling. This will be further described below in FIG. 46.

Referring to FIG. 44, it is possible to determine a prediction mode based on cu_skip_flag, pred_mode_flag, and pred_mode_ibc_flag. Also, prediction may be performed based on the determined prediction mode. That is, a prediction signal may be generated based on the determined prediction mode, and a block may be reconstructed based on the determined prediction mode.

Referring to Figure 44, etc. pcm_flag, pcm_alignment_zero_bit, intra_mip_flag, intra_mip_mpm_flag, intra_mip_mpm_idx, intra_mip_mpm_remainder, intra_luma_ref_idx, intra_subpartitions_mode_flag, intra_subpartitions_split_flag, intra_luma_mpm_flag, intra_luma_not_planar_flag, intra_luma_mpm_idx, intra_luma_mpm_remainder, intra_chroma_pred_mode may be a syntax element related to the intra prediction. In addition, the syntax element related to the intra prediction may be a syntax element related to MODE_INTRA. In addition, it is possible to perform prediction based on a syntax element related to the intra prediction.

45 is a diagram illustrating skip mode and prediction mode signaling according to an embodiment of the present invention.

As described with reference to FIG. 44, there may be a relationship between cu_skip_flag, pred_mode_flag, pred_mode_ibc_flag, and prediction mode. It can also be related to block size.

Referring to FIG. 45, whether to pars a syntax element afterwards may be determined based on cu_skip_flag. For example, when cu_skip_flag is 1, syntax elements other than pred_mode_ibc_flag and merge_data syntax structure for P slice or B slice may not be parsed after cu_skip_flag parsing in the coding unit. In addition, when cu_skip_flag is 1, syntax elements of merge_idx two times for I slice may not be parsed after cu_skip_flag parsing in the coding unit. In addition, when cu_skip_flag is 0, the coding unit may not be skipped. If cu_skip_flag does not exist, the value can be inferred to 0.

Referring to FIG. 45, it is possible to determine CuPredMode based on pred_mode_flag. According to an embodiment, when pred_mode_flag is 0, it may mean that an inter prediction mode is used, and CuPredMode may be set to MODE_INTER. In addition, when pred_mode_flag is 1, it may mean that the intra prediction mode is used, and CuPredMode may be set to MODE_INTRA. Also, based on pred_mode_ibc_flag, CuPredMode may be set to a value other than MODE_INTER and MODE_INTRA described.

According to an embodiment of the present invention, when pred_mode_flag does not exist, when both width and height are 4, the value of pred_mode_flag may be inferred to 1. In addition, when pred_mode_flag does not exist, when the width or height is not 4, the value of pred_mode_flag may be inferred to 1 for I slice and 0 for P or B slice.

Referring to FIG. 45, pred_mode_ibc_flag may indicate whether the IBC prediction mode is used. For example, when pred_mode_ibc_flag is 1, the IBC prediction mode may be used, and when pred_mode_ibc_flag is 0, the IBC prediction mode may not be used. Also, when pred_mode_ibc_flag is 1, CuPredMode may be set to MODE_IBC.

If pred_mode_ibc_flag does not exist, the value can be inferred as follows. 1) If cu_skip_flag is 1 and both width and height are 4, you can infer pred_mode_ibc_flag to 1, 2) otherwise, if both width and height are 128, you can infer pred_mode_ibc_flag to 0, and 3) not In case I slice, pred_mode_ibc_flag may be inferred as sps_ibc_enabled_flag value, and in P or B slice, pred_mode_ibc_flag may be inferred as 0.

As described with reference to FIG. 44, when both width and height are 4 in the invention of FIG. 45, when MODE_INTER is not used, when both width and height are 128, it may be a specific embodiment when MODE_IBC is not used.

46 is a diagram showing a coding unit syntax structure according to an embodiment of the present invention.

As described with reference to FIG. 44, the prediction mode may be limited based on the block size, and thus more efficient signaling may be performed.

According to an embodiment of the present invention, whether to parsing cu_skip_flag, pred_mode_flag, and pred_mode_ibc_flag may be determined based on a slice type and a block size. This is because prediction mode may be limited based on slice type or block size. For example, in the case of I slice, whether to parsing cu_skip_flag, pred_mode_flag, and pred_mode_ibc_flag may be determined based on the block size. For example, in the case of I slice and a block size in which MODE_IBC cannot be used, cu_skip_flag, pred_mode_flag, and pred_mode_ibc_flag may not be parsed. Also, if it is I slice and is a block size that cannot use MODE_IBC, CuPredMode can be determined and set as MODE_INTRA. In an embodiment, a block size in which MODE_IBC cannot be used may be a case where both width and height are 128. In another embodiment, a block size in which MODE_IBC cannot be used may be when both width and height are 128 or more. In addition, if it is I slice and is a block size that cannot use MODE_IBC, cu_skip_flag can be inferred to 0, pred_mode_flag can be inferred to 1, and pred_mode_ibc_flag can be infered to 0.

Referring to FIG. 46, when slice_type is I, cbWidth is 128, and cbHeight is 128, cu_skip_flag, pred_mode_flag, and pred_mode_ibc_flag may not be parsed. At this time, after confirming that slice_type is I, cbWidth is 128, and cbHeight is 128, a conditional operation to determine whether to parsing cu_skip_flag, pred_mode_flag, and pred_mode_ibc_flag may not be required. In this case, cu_skip_flag, pred_mode_flag, and pred_mode_ibc_flag parsing can be skipped without additional operations. That is, when slice_type is I, cbWidth is 128, and cbHeight is 128, the amount of computation can be reduced because the Condition 1, Condition 2, and Condition 3 checks shown in FIG. 46 are not required. Also, in this case, cu_skip_flag may be inferred to 0, pred_mode_flag may be inferred to 1, and pred_mode_ibc_flag may be inferred to 0. Also, in this case, CuPredMode may be determined and set as MODE_INTRA. In addition, when slice_type is not I, cbWidth is not 128, or cbHeight is not 128, it may be possible to parsing cu_skip_flag, pred_mode_flag, pred_mode_ibc_flag, and Condition 1, Condition 2, and Condition 3 of FIG. 46 may be required.

In another embodiment, when slice_type is I, cbWidth is 128 or more, and cbHeight is 128 or more, cu_skip_flag, pred_mode_flag, and pred_mode_ibc_flag may not be parsed. At this time, after confirming that slice_type is I, cbWidth is 128 or more, and cbHeight is 128 or more, a conditional operation that determines whether to parsing cu_skip_flag, pred_mode_flag, and pred_mode_ibc_flag may not be required. In this case, cu_skip_flag, pred_mode_flag, and pred_mode_ibc_flag parsing can be skipped without additional operations. That is, in this case, since it is not necessary to check Condition 1, Condition 2, and Condition 3 shown in FIG. 46, the amount of computation can be reduced. Also, in this case, cu_skip_flag may be inferred to 0, pred_mode_flag may be inferred to 1, and pred_mode_ibc_flag may be inferred to 0. Also, in this case, CuPredMode may be determined and set as MODE_INTRA. In addition, when slice_type is not I, cbWidth is less than 128, or cbHeight is less than 128, it may be possible to parsing cu_skip_flag, pred_mode_flag, pred_mode_ibc_flag, and Condition 1, Condition 2, and Condition 3 of FIG. 46 may be required.

Condition 1, Condition 2, and Condition 3 may be conditions based on at least one of treeType, cbWidth, cbHeight, sps_ibc_enabled_flag, cu_skip_flag, and CuPredMode, as shown in FIG. 46.

47 is a diagram showing a coding unit syntax structure according to an embodiment of the present invention.

As described with reference to FIG. 44, the prediction mode may be limited based on the block size, and thus more efficient signaling may be performed.

As described above, it is possible to determine whether to pars the cu_skip_flag based on the slice type and block size. This is because prediction mode may be limited based on slice type or block size. For example, in the case of I slice and a block size in which MODE_IBC cannot be used, cu_skip_flag may not be parsed. Also, in this case, the cu_skip_flag value can be inferred to 0. In addition, it is possible to pars cu_skip_flag if it is not I slice or if it is a block size that can use MODE_IBC. More specifically, the block size for which MODE_IBC cannot be used may be a case where both width and height are 128. As another example, the block size for which MODE_IBC cannot be used may be when both width and height are 128 or more.

Referring to FIG. 47, when slice_type is I, cbWidth is 128, and cbHeight is 128, Condition 1 is not satisfied, and cu_skip_flag may not be parsed. At this time, cu_skip_flag may be inferred to 0.

Unlike FIG. 46, in the embodiment of FIG. 47, even in the case of I slice and a block size in which MODE_IBC cannot be used, whether to parsing pred_mode_flag and pred_mode_ibc_flag can be checked. That is, even if it is I slice and is a block size in which MODE_IBC cannot be used, Condition 2 and Condition 3 of FIG. 47 can be checked. Accordingly, the embodiment of FIG. 47 may include more operations than the embodiment of FIG. 46.

48 is a diagram showing a coding unit syntax structure according to an embodiment of the present invention.

The embodiment of FIG. 48 is a simplified condition based on the embodiment of FIG. 46.

Referring to FIG. 48, when determining whether to pars pred_mode_ibc_flag, whether to check the block size condition based on slice_type may be different. That is, whether to check the block size condition based on slice_type in Condition 3 of FIG. 48 may be different. For example, in the case of I slice, the block size may not be referred to when determining whether to pars the pred_mode_ibc_flag. For example, in the case of I slice, only cu_skip_flag and sps_ibc_enabled_flag can be referenced when determining whether to pars pred_mode_ibc_flag. For example, in the case of I slice, it is possible to check whether the pred_mode_ibc_flag is parsed without checking whether the width or height is 128 or not. As another embodiment, in the case of I slice, it is possible to check whether the pred_mode_ibc_flag is parsed without a procedure of checking whether the width or height is less than 128 or whether both the width and height are 128 or more.

In the embodiment of FIG. 46, when determining whether to pars pred_mode_ibc_flag in the case of I slice, width and height are referred to. In the embodiment of FIG. 46, when determining whether to pars pred_mode_ibc_flag in the case of I slice, when the width or height is not 128, the pred_mode_ibc_flag may be parsed. However, in the embodiment of FIG. 48, in the case of I slice, pred_mode_ibc_flag may be parsed regardless of the block size.

In addition, in the embodiment of FIG. 48, if it is not an I slice (for example, a P or B slice), it may be determined whether to pars the pred_mode_ibc_flag with reference to the block size. For example, when it is not I slice and CuPredMode is not MODE_INTRA, it may be determined whether to pars pred_mode_ibc_flag with reference to block size. For example, if it is not I slice and CuPredMode is MODE_INTER, it may be determined whether to pars pred_mode_ibc_flag with reference to block size. For example, when referring to the block size, you can check whether the width or height is 128. As another example, when referring to the block size, you can check whether the width or height is less than 128, and whether both width and height are 128 or more. In addition, if it is not I slice, both width and height are 4, and if cu_skip_flag is 0, additional block size check (for example, whether width or height is 128) may not be necessary.

Accordingly, the embodiment of FIG. 48 can use a smaller amount of computation than the embodiment of FIG. 46.

The embodiments of the present invention described above can be implemented through various means. For example, embodiments of the present invention may be implemented by hardware, firmware, software, or a combination thereof.

In the case of hardware implementation, the method according to embodiments of the present invention includes one or more Application Specific Integrated Circuits (ASICs), Digital Signal Processors (DSPs), Digital Signal Processing Devices (DSPDs), and Programmable Logic Devices (PLDs). , Field Programmable Gate Arrays (FPGAs), processors, controllers, microcontrollers, microprocessors, and the like.

In the case of implementation by firmware or software, the method according to the embodiments of the present invention may be implemented in the form of a module, procedure, or function that performs the functions or operations described above. The software code can be stored in a memory and driven by a processor. The memory may be located inside or outside the processor, and data may be exchanged with the processor through various known means.

The above description of the present invention is for illustrative purposes only, and those of ordinary skill in the art to which the present invention pertains will be able to understand that it can be easily modified into other specific forms without changing the technical spirit or essential features of the present invention. will be. Therefore, it should be construed that the embodiments described above are illustrative in all respects and are not limiting. For example, each component described as a single type may be implemented in a distributed manner, and similarly, components described as being distributed may also be implemented in a combined form.

The scope of the present invention is indicated by the claims to be described later rather than the detailed description, and all changes or modified forms derived from the meaning and scope of the claims and their equivalent concepts should be interpreted as being included in the scope of the present invention. do.

100: encoding device 200: decoding device

Claims (1)

Video signal processing apparatus and method.

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