RU2818972C2 - Method and device for encoding/decoding image signals - Google Patents

Abstract

FIELD: data processing.

SUBSTANCE: invention relates to video encoding or decoding. Disclosed is a method of decoding an image, comprising steps of: generating a list of candidates for merging a current block; indicating any of the plurality of merge candidates included in the merge candidate list; based on the first affine initial vector and the second affine initial vector of the said candidate for merging, the introduction of the first affine initial vector and the second affine initial vector of the current block; using the first affine initial vector and the second affine initial vector of the current block, introducing an affine vector with respect to a sub-block in the current block and based on the affine vector, performing prediction with motion compensation with respect to the sub-block.

EFFECT: high efficiency and speed of encoding.

10 cl, 49 dwg, 15 tbl

Description

FIELD OF TECHNOLOGY TO WHICH THE INVENTION RELATES

[0001] The present invention relates to a method and apparatus for encoding or decoding a video signal.

BACKGROUND OF THE INVENTION

[0002] With the trend toward larger display panels, demand for high-definition video services is increasing. The biggest problem of high-definition video services is that the data volume increases significantly, and to solve this problem, research has been actively carried out to improve the video compression ratio. As a representative example, the Joint Video Coding Group (JCT-VC) within the Video Coding Experts Group (VCEG) within the Telecommunication Standardization Sector of the International Telecommunication Union (ITU-T) and the Moving Picture Experts Group (MPEG) was established in 2009. . JCT-VC proposed High Efficiency Video Coding (HEVC), which is a video compression standard whose compression efficiency is approximately twice that of H.264/AVC, and was approved as a standard on January 25, 2013. With the rapid development of high-definition video services, HEVC performance is gradually revealing its limitations.

SUMMARY OF THE INVENTION

[Technical challenge]

[0003] The present invention is directed to providing a method and apparatus for encoding or decoding a residual coefficient when encoding or decoding a video signal.

[0004] The present invention is directed to providing a method and apparatus for encoding or decoding a residual coefficient using a flag for comparing the size of the residual coefficient with a threshold value when encoding or decoding a video signal.

[0005] The present invention is directed to providing a method and apparatus for encoding or decoding a residual coefficient using a flag indicating whether the residual coefficient is an even number or an odd number when encoding or decoding a video signal.

[0006] The technical problems to be solved by the present invention are not limited to the above problems, and other technical problems that are not described herein will be clearly understood by those skilled in the art from the following description.

[Technical solution]

[0007] According to one broad aspect, the present invention provides a method for decoding video, the method including: analyzing a non-zero flag indicating whether a residual coefficient is non-zero from a bit stream; analyzing the absolute value information to determine the absolute value of the residual coefficient from the bit stream, when the non-zero flag indicates that the residual coefficient is not non-zero; and determining an absolute value of the residual coefficient based on the absolute value information, wherein the absolute value information includes a residual coefficient comparison flag indicating whether the residual coefficient is greater than the first value, and a parity flag is further analyzed from the bit stream only when the residual coefficient greater than the first value.

[0008] According to another broad aspect, the present invention provides a video encoding method, the method including: encoding a non-zero flag indicating whether a residual coefficient is non-zero; and encoding absolute value information for determining the absolute value of the residual coefficient when the residual coefficient is not non-zero, wherein the absolute value information includes a residual coefficient comparison flag indicating whether the residual coefficient is greater than the first value, and a parity flag for the residual coefficient further code only when the residual coefficient is greater than the first value.

[0009] In some embodiments, a parity flag may indicate whether the residual coefficient value is an even number or an odd number.

[0010] In some embodiments, when the residual coefficient is greater than the first value, a first adjusted residual coefficient comparison flag indicating whether the adjusted residual coefficient obtained by bit shifting the residual coefficient to the right by 1 than the second value can be further analyzed .

[0011] In some embodiments, when the adjusted residual coefficient is less than or equal to the second value, the residual coefficient may be determined to be 2N or 2N+1 depending on the value of the parity flag.

[0012] In some embodiments, when the adjusted residual ratio is greater than the second value, a second adjusted residual ratio comparison flag indicating whether the adjusted residual ratio is greater than the third value may be further analyzed.

[0013] In some embodiments, when the adjusted residual coefficient is greater than the second value, the residual value information may be further analyzed and the residual value information may be a value obtained by subtracting the second value from the adjusted residual coefficient.

[0014] The features summarized above with respect to the present invention are merely illustrative aspects of the detailed description of the present invention described below and do not limit the scope of the present invention.

[Buffs]

[0015] According to the present invention, the residual coefficient can be efficiently encoded or decoded.

[0016] According to the present invention, it is possible to efficiently encode or decode a residual coefficient by using a flag to compare the size of the residual coefficient with a threshold value.

[0017] According to the present invention, it is possible to efficiently encode or decode the residual coefficient using a flag indicating whether the residual coefficient is an even number or an odd number.

[0018] The beneficial effects of the present invention are not limited to the above effects, and other beneficial effects that are not described herein will be clearly understood by those skilled in the art from the following description.

BRIEF DESCRIPTION OF GRAPHIC MATERIALS

[0019] In FIG. 1 is a block diagram of a video encoder according to an embodiment of the present invention.

[0020] In FIG. 2 is a block diagram of a video decoder according to an embodiment of the present invention.

[0021] In FIG. 3 is a schematic diagram showing a basic element of a code tree according to an embodiment of the present invention.

[0022] In FIG. 4 is a schematic diagram showing various types of coding block partitioning.

[0023] In FIG. 5 is a schematic diagram illustrating the partitioning aspect of a code tree element.

[0024] In FIG. 6 shows an example in which a block smaller than a code tree element of a predetermined size occurs at the edge of the image.

[0025] In FIG. 7 is a schematic diagram showing an example in which quaternary tree partitioning is performed on an atypical boundary edge block.

[0026] In FIG. 8 is a schematic diagram showing an example in which quaternary tree partitioning is performed on a block adjacent to an image edge.

[0027] In FIG. 9 is a schematic view showing a dividing aspect of a block adjacent to an image edge.

[0028] In FIG. 10 is a schematic diagram showing the encoding aspect of a block adjacent to an image edge.

[0029] In FIG. 11 is a flowchart of an inter-image prediction method according to an embodiment of the present invention.

[0030] In FIG. 12 shows a flowchart of the process of obtaining information about the movement of the current block in the merge mode.

[0031] In FIG. 13 is a schematic diagram illustrating candidate blocks used to obtain a merge candidate.

[0032] In FIG. 14 is a schematic diagram showing locations of reference samples.

[0033] In FIG. 15 is a schematic diagram illustrating candidate blocks used to obtain a merge candidate.

[0034] In FIG. 16 is a schematic diagram showing an example in which the location of the reference count is changed.

[0035] In FIG. 17 is a schematic diagram showing an example in which the location of the reference count is changed.

[0036] In FIG. 18 is a schematic diagram for describing an aspect of updating an inter-section traffic information table.

[0037] In FIG. 19 is a schematic diagram showing an aspect of updating an inter-site merge candidate table.

[0038] In FIG. 20 is a schematic diagram showing an example in which the index of a previously stored inter-site merge candidate is updated.

[0039] In FIG. 21 is a schematic diagram showing the location of a representative subblock.

[0040] In FIG. 22 shows an example in which a table of inter-section motion information is generated for each inter-picture prediction mode.

[0041] In FIG. 23 is a schematic diagram showing an example in which a cross-section merging candidate included in the long-term traffic information table is added to the merging candidate list.

[0042] In FIG. 24 is a schematic diagram showing an example in which redundancy checking is performed on only some merge candidates.

[0043] In FIG. 25 is a schematic diagram showing an example in which redundancy control is omitted with respect to a particular merger candidate.

[0044] In FIG. 26 is a schematic diagram showing an example in which a candidate block included in the same parallel merge region as the current block is set to unavailable as a merge candidate.

[0045] In FIG. 27 is a schematic diagram showing a timing table of motion information.

[0046] In FIG. 28 is a schematic diagram showing an example of merging a temporary motion information table with an inter-section motion information table.

[0047] In FIG. 29 is a flowchart of an intra prediction method according to an embodiment of the present invention.

[0048] In FIG. 30 is a schematic diagram showing reference samples included in each reference sample line.

[0049] In FIG. 31 is a schematic diagram showing intra prediction modes.

[0050] In FIG. 32 and 33 are schematic diagrams showing an example of a one-dimensional array in which reference samples are arranged in a line.

[0051] In FIG. 34 is a schematic view illustrating the angles formed between a straight line parallel to the x-axis and the directional intra prediction modes.

[0052] In FIG. 35 is a schematic view showing an aspect in which a prediction count is obtained when the current block has a non-square shape.

[0053] In FIG. 36 is a schematic diagram showing wide-angle intra prediction modes.

[0054] In FIG. 37 is a schematic diagram showing an application aspect of PDPC.

[0055] In FIG. 38 and 39 are schematic diagrams showing a subblock to be subjected to the second transformation.

[0056] In FIG. 40 is a schematic diagram for describing an example in which the transformation type of the current block is determined.

[0057] In FIG. 41 is a flowchart showing a residual coefficient encoding method.

[0058] In FIG. 42 and 43 are schematic diagrams showing the arrangement of residual coefficients for each scanning order.

[0059] In FIG. 44 shows an example in which the location of the last non-zero coefficient is encoded.

[0060] In FIG. 45 is a flowchart of a process for encoding the absolute value of a residual coefficient.

[0061] In FIG. 46 is a flowchart of a process for encoding the absolute value of a residual coefficient.

[0062] In FIG. 47 is a flowchart of a process for encoding the absolute value of a residual coefficient.

[0063] In FIG. 48 is a flowchart showing the process of determining the quality of a block.

[0064] In FIG. 49 shows predefined candidate filters.

DETAILED DESCRIPTION

[0065] Embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0066] Video is encoded and decoded in block elements. As an example, encoding and decoding processing such as transform, quantization, prediction, in-loop filtering, or reconstruction may be performed on an encoding block, a transform block, or a prediction block.

[0067] Hereinafter, the block to be encoded or decoded will be referred to as the "current block". As an example, the current block may indicate an encoding block, a transform block, or a prediction block depending on the current stage of encoding or decoding processing.

[0068] In addition, the term "element" as used herein may be understood to indicate a base element for performing a particular encoding and decoding process, and the term "block" may be understood to indicate an array of samples of a predetermined size. Unless otherwise noted, the terms "block" and "element" may be used interchangeably. As an example, in the following embodiments, a coding block and a coding element may be understood to have equivalent meanings.

[0069] In FIG. 1 is a block diagram of a video encoder according to an embodiment of the present invention.

[0070] Referring to FIG. 1, video encoding apparatus 100 may include an image splitter 110, predictors 120 and 125, an inverter 130, a quantizer 135, a reorderer 160, an entropy encoder 165, an inverse quantizer 140, an inverter 145, a filter 150, and a memory 155.

[0071] Elements in FIG. 1 are shown independently to represent various characteristic functions in a video encoding apparatus, and each of the elements is not intended to be implemented in a separate hardware unit or as a single software unit. In other words, for ease of description, the elements are arranged independently of each other. To perform functions, at least two elements may be combined into one element, or one element may be divided into multiple elements. In this case, the element combination embodiment and the element separation embodiment are included in the scope of the present invention without departing from the essence of the present invention.

[0072] In addition, some of the elements may not be essential elements for performing essential functions in the present invention, but may simply be optional elements to enhance performance. The present invention can be implemented by including only the elements necessary to implement the essence of the present invention, and not elements used only to improve performance. Even a structure including only essential elements and not optional elements used only to improve performance is within the scope of the present invention.

[0073] The image splitter 110 may split the input image into at least one processing element. In this case, the processing element may be a prediction element (PU), a transformation element (TU), or a coding element (CU). The image partitioning apparatus 110 may partition one image into a plurality of combinations of encoding elements, prediction elements, and transform elements, and may select one combination of encoding elements, prediction elements, and transform elements according to a predetermined criterion (eg, a cost function) to encode the image.

[0074] For example, one image may be divided into multiple encoding elements. A recursive tree structure, such as a quaternary tree structure, can be used to partition the image into encoding elements. An encoding element split into other encoding elements using a single image or the largest encoding element as the root may have a number of child nodes corresponding to the number of encoding elements split. An encoding element that is no longer split due to a predefined constraint serves as a leaf node. That is, when it is assumed that only a square partition is possible for one encoding element, one encoding element can be divided into at most four other encoding elements.

[0075] In further embodiments of the present invention, an encoding element may refer to an element configured to perform encoding or an element configured to perform decoding.

[0076] One coding element may be divided into at least one or more equally sized square or rectangular shaped prediction elements, and may be divided into prediction elements such that one of the prediction elements differs from another prediction element in shape and/or size .

[0077] When a prediction element subject to intra prediction is generated based on a coding element, and the coding element is not a minimum coding element, intra prediction can be performed without dividing the coding element into a plurality of N×N prediction elements.

[0078] Predictors 120 and 125 may include an inter-picture prediction predictor 120 configured to perform inter-picture prediction, and an internal predictor 125 configured to perform intra-prediction. Predictors 120 and 125 can determine whether to perform intra prediction or use inter-picture prediction with respect to prediction elements, and can determine detailed information (eg, intra prediction mode, motion vector, reference picture, etc.) corresponding each method of prediction. In this case, the processing element in which the prediction is performed may be different from the processing element in which the prediction method and specific details are determined. For example, prediction method, prediction mode, etc. may be determined by a prediction element, and the prediction may be performed by a transformation element. A residual value (residual block) between the generated prediction block and the original block may be input to the converter 130. Moreover, motion vector information, prediction mode information, etc., which are used for prediction, in addition to the residual value, may be encoded by entropy encoder 165 and transferred to the decoder. When a particular encoding mode is used, the original block can be encoded unchanged and passed to the decoder without predictors 120 and 125 generating the prediction block.

[0079] The inter-image prediction predictor 120 may predict a prediction element based on information about at least one of an image preceding the current image or an image following the current image, and in some cases, the prediction element may be predicted based on the information about a certain area of the current image in which encoding is carried out. The inter-image predictor 120 may include a reference image interpolator, a motion predictor, and a motion compensator.

[0080] The reference image interpolator can obtain information about the reference image from the memory 155 and can generate information about pixels whose number is less than or equal to an integer number of pixels from the reference image. In the case of luminance pixels, a DCT-based 8-point interpolation filter having different filter coefficients can be used to generate information about pixels whose number is less than or equal to the integer number of pixels in 1/4-pixel elements. For chrominance signals, a DCT-based 4-point interpolation filter having different filter coefficients can be used to generate information about pixels whose number is less than or equal to the integer number of pixels in 1/8-pixel elements.

[0081] The motion predictor may perform motion prediction based on a reference image interpolated by a reference image interpolator. As a method for calculating the motion vector, various methods may be used, such as the Full Block Matching Algorithm (FBMA), the Three-Stage Search (TSS) algorithm, and the New Three-Stage Search (NTS) algorithm. The motion vector can have a motion vector value in 1/2 or 1/4 pixel elements based on the interpolated pixels. The motion prediction element may predict the current prediction element using a motion prediction method differently. As the motion prediction method, various methods such as a skip method, a merging method, an advanced motion vector prediction (AMVP) method, and an intra-block copy method can be used.

[0082] The internal predictor 125 may generate a prediction element based on information about a reference pixel adjacent to the current block, which is information about a pixel in the current image. When the nearest block of the current prediction element is a block subject to inter-picture prediction, and thus the reference pixel is a pixel subject to inter-picture prediction, the reference pixel information of the nearest block subject to intra-prediction may be used instead a reference pixel included in a block subject to inter-image prediction. That is, when a reference pixel is not available, at least one available reference pixel can be used instead of the unavailable reference pixel information.

[0083] Intra prediction prediction modes may include a directional prediction mode that uses reference pixel information depending on the prediction direction, and an omnidirectional mode that does not use directionality information when making prediction. The mode for predicting luminance information and the mode for predicting chrominance information may be different, and information about the intra prediction mode used to predict luminance information or information about a predicted luminance signal may be used to predict chrominance information.

[0084] When intra prediction is performed and the size of the prediction element is equal to the size of the transform element, intra prediction may be performed on the prediction element based on pixels located to the left of the prediction element, pixels located in the upper left corner of the prediction element, and pixels located in the top of the prediction element. However, when intra prediction is performed and the prediction element is different in size from the transform element, intra prediction can be performed using a reference pixel based on the transform element. In addition, intra prediction using N×N partitioning only for the minimum coding element can be used.

[0085] In the intra prediction method, a prediction block may be generated after applying an adaptive intra smoothing (AIS) filter to a reference pixel depending on the prediction mode. The type of AIS filter applied to the reference pixel may vary. For the purpose of executing the intra prediction method, the intra prediction mode of the current prediction element can be predicted from the intra prediction mode of the prediction element adjacent to the current prediction element. When predicting the prediction mode of the current prediction element using mode information predicted from the nearest prediction element, information indicating that the current prediction element and the nearest prediction element have the same prediction mode can be transmitted using the predetermined flag information when the intra prediction mode the current prediction element is the same as the intra prediction mode of the nearest prediction element, and entropy encoding may be performed to encode prediction mode information of the current block when the prediction mode of the current prediction element is different from the prediction mode of the nearest prediction element.

[0086] In addition, a residual block containing information about a residual value that represents the difference between a prediction element being predicted and an original prediction element block may be generated based on the prediction elements generated by predictors 120 and 125. The generated residual block may be introduced into the converter 130.

[0087] Transformer 130 may transform a residual block containing residual value information between the original block and the prediction elements generated by predictors 120 and 125 using a transformation method such as discrete cosine transform (DCT), discrete sine transform (DST), and KLT. Whether to apply DCT, DST or KLT to transform the residual block can be determined based on information about the intra prediction mode of the prediction element used to generate the residual block.

[0088] Quantizer 135 may quantize values that are converted to the frequency domain by converter 130. Quantization factors may vary depending on the block or importance of the image. The values calculated by quantizer 135 may be passed to inverse quantizer 140 and reorderer 160.

[0089] Reorderer 160 may perform reordering of coefficient values with respect to the quantized residual values.

[0090] The rearranger 160 can change the coefficients from a two-dimensional block form to a one-dimensional vector form using a coefficient scanning method. For example, reorderer 160 may scan DC coefficients and even high frequency coefficients using a zigzag scanning technique to convert the coefficients into one-dimensional vector form. Depending on the intra prediction mode and the size of the transform element, instead of zigzag scanning, vertical scanning may be used, in which 2D block type coefficients are scanned in the column direction, or horizontal scanning, in which 2D block type coefficients are scanned in the row direction. That is, the reordering apparatus can determine the scanning method to be used from zigzag scanning, vertical scanning, and horizontal scanning, depending on the transform element size and the intra prediction mode.

[0091] Entropy encoder 165 may perform entropy encoding based on values calculated by reordering apparatus 160. For entropy coding, various encoding techniques can be used, for example, such as exponential Golomb coding, context-adaptive variable-length coding (CAVLC), and context-adaptive binary arithmetic coding (CABAC).

[0092] The entropy encoder 165 can encode various information such as residual coefficient information and block type information for an encoding element, prediction mode information, split element information, prediction element information, transmission element information, vector information motion, reference frame information, block interpolation information, and filtering information from reorderer 160 and predictors 120 and 125.

[0093] The entropy encoder 165 may perform entropy encoding on the values of the coding element coefficients input from the reordering device 160.

[0094] Inverse quantizer 140 may inversely quantize values quantized by quantizer 135, and inverse transformer 145 may inversely transform values transformed by transformer 130. The residual value generated by inverse quantizer 140 and inverse transformer 145 may be combined with a prediction element predicted by the device motion estimation, motion compensator, and internal predictor from predictors 120 and 125 to generate a reconstructed block.

[0095] Filter 150 may employ at least one of a deblocking filter, an offset corrector, and an adaptive loop filtering (ALF) filter.

[0096] The deblocking filter can remove block distortion that occurred due to boundaries between blocks of the reconstructed image. For the purpose of determining whether to perform deblocking, you can determine whether to apply a deblocking filter to the current block based on the pixels included in multiple rows or columns in the block. When a deblocking filter is applied to a block, a strong filter or a weak filter may be applied depending on the required deblocking filtering strength. In addition, when a deblock filter is applied, vertical filtering and horizontal filtering can be performed such that horizontal filtering and vertical filtering are processed in parallel.

[0097] The offset corrector can correct the offset from the original image in the deblocking image in pixel elements. A method of dividing pixels included in an image into a certain number of regions, determining an area to be offset, and applying the offset to the specific area, or a method of applying the offset taking into account edge information of each pixel can be used to perform offset correction with respect to a particular image. .

[0098] ALF may be performed based on values obtained by comparing the filtered reconstructed image and the original image. By dividing the pixels included in the image into predefined groups and defining a filter to be applied to each group, differential filtering can be performed on each group. Information about whether to apply ALF may be transmitted on a per coding unit (CU) basis, and the shape and filter coefficients of the AFL filter to be applied may vary from block to block. Moreover, the ALF filter in the same form (fixed form) can be applied regardless of the characteristic of the block to be filtered.

[0099] Memory 155 may store the reconstructed block or image calculated by filter 150. The stored reconstructed block or image may be provided to predictors 120 and 125 when performing inter-image prediction.

[00100] In FIG. 2 is a block diagram of a video decoder according to an embodiment of the present invention.

[00101] Referring to FIG. 2, video decoder 200 may include an entropy decoder 210, a reorderer 215, an inverse quantizer 220, an inverse transformer 225, predictors 230 and 235, a filter 240, and a memory 245.

[00102] When a video bitstream is input from a video encoder, the input bitstream can be decoded according to a procedure opposite to that of the video encoder.

[00103] The entropy decoder 210 may perform entropy decoding according to a procedure opposite to the procedure in which the video encoder entropy encoder performs entropy encoding. For example, to match the method performed by a video encoder, various methods such as exponential Golomb coding, context-adaptive variable-length coding (CAVLC), and context-adaptive binary arithmetic coding (CABAC) may be used.

[00104] The entropy decoder 210 can decode information related to intra and inter-picture prediction performed by the encoder.

[00105] The reordering apparatus 215 may perform reordering on the bitstream subjected to entropy decoding by the entropy decoder 210 based on the reordering method used by the encoder. Reorderer 215 may recover coefficients expressed in one-dimensional vector form into two-dimensional block type coefficients to reorder the two-dimensional block type coefficients. The reordering apparatus 215 may receive information related to coefficient scanning performed by the encoder and perform reordering by an inverse scanning method based on the scanning order of the encoder.

[00106] Inverse quantizer 220 may perform inverse quantization based on the values of the reordered block coefficients and quantization parameters provided by the encoder.

[00107] The inverse transformer 225 may perform an inverse DCT, inverse DST, and inverse KLT on a quantization result performed by the video encoder, wherein the inverse DCT, inverse DST, and inverse KLT are transforms inverse to the transforms that were performed by the transform element, that is, the DCT , DST and KLT. The inverse conversion may be performed based on the transfer element determined by the video encoder. In the video decoder inverter 225, transform methods (eg, DCT, DST, and KLT) may be selectively performed depending on multiple pieces of information such as prediction method, current block size, and prediction direction.

[00108] Predictors 230 and 235 may generate a prediction block based on information related to prediction block generation that is provided by entropy decoder 210 and information about a previously decoded block or image that is provided by storage device 245.

[00109] As described above, when intra prediction is performed in the same manner as in a video encoder and the prediction element is equal in size to the transform element, intra prediction may be performed on the prediction element based on pixels located to the left of the prediction element, pixels located in the upper left corner of the prediction element, and pixels located at the top of the prediction element. On the other hand, when intra prediction is performed and the prediction element is different in size from the transform element, intra prediction can be performed using a reference pixel based on the transform element. In addition, intra prediction using N×N partitioning only for the minimum coding element can be used.

[00110] Predictors 230 and 235 may include a prediction element qualifier, an inter-image prediction predictor, and an internal predictor. The prediction element determiner may receive various information such as information about the prediction element, information about the prediction mode for the intra prediction method, and information related to motion prediction for the inter-picture prediction method from the entropy decoder 210, classify the prediction element in the current element encoding and determine whether the prediction element performs inter-picture prediction or intra prediction. Using information necessary for inter-picture prediction of the current prediction element provided by the video encoder, inter-picture predictor 230 can perform inter-picture prediction regarding the current prediction element based on information included in at least one of an image preceding the current image including the current prediction element, or an image following the current image. Alternatively, inter-image prediction may be performed based on information about some previously reconstructed regions in the current image including the current prediction element.

[00111] The inter-picture prediction predictor 230 can determine whether a motion prediction method for a prediction element that is included in a corresponding encoding element is a skip mode, a merge mode, an AMVP mode, or an intra-block copy mode based on the encoding element to perform prediction carried out between images.

[00112] The internal predictor 235 may generate a prediction block based on information about the pixels in the current image. When the prediction element is a prediction element subject to intra prediction, the intra predictor 235 may perform intra prediction based on the intra prediction mode information of the prediction element provided by the video encoder. The internal predictor 235 may include an AIS filter, a reference pixel interpolator, and a DC filter. The AIS filter, which is a part that performs filtering on a reference pixel of the current block, can determine whether to apply filtering depending on the prediction mode of the current prediction element. The AIS filter may perform AIS filtering on a reference pixel of the current block using information about the AIS filter and prediction mode of the prediction element provided by the video encoder. When the prediction mode of the current block is a mode in which AIS filtering is not performed, the AIS filter may not be applied.

[00113] When the prediction mode of the prediction block is a prediction mode in which intra prediction is performed based on a pixel value obtained by interpolating a reference pixel, a reference pixel interpolator may interpolate the reference pixel to generate a reference pixel at a pixel element less than or equal to an integer. When the prediction mode of the current prediction element is a prediction mode in which a prediction block is generated without interpolating a reference pixel, the reference pixel cannot be interpolated. When the prediction mode of the current block is the DC mode, the DC filter can generate the prediction block by filtering.

[00114] The reconstructed block or image may be provided to filter 240. Filter 240 may include a deblocking filter, an offset corrector, and an ALF filter.

[00115] Filter 240 may receive from the video encoder information about whether a deblocking filter is applied to a corresponding block or image, or information about whether a strong filter is applied or a weak filter is applied when the deblocking filter is applied. A video decoder deblock filter may receive information related to the deblock filter that is provided by the video encoder, and the video decoder may perform deblocking filtering on the corresponding block.

[00116] The offset corrector can perform offset correction on the reconstructed image based on the type of offset correction, offset value information, and the like that is applied to the image during encoding.

[00117] ALF may be applied to an encoding element based on information about whether to apply ALF, ALF coefficient information, and the like that is provided from the encoder. ALF information may be provided by inclusion in a specific parameter set.

[00118] Storage device 245 may store the reconstructed image or block such that the image or block can be used as a reference image or reference block, and may also provide the reconstructed image to an output element.

[00119] In FIG. 3 is a schematic diagram showing a basic element of a code tree according to an embodiment of the present invention.

[00120] The largest encoding element may be defined as a code tree block. A single image is divided into many code tree units (CTUs). The code tree element that represents the largest coding element may be called the largest coding unit (LCU). In fig. Figure 3 shows an example in which one image is divided into many code tree elements.

[00121] The code tree element size can be set at the image level or the sequence level. To this end, information indicating the size of a code tree element may be conveyed by an image parameter set or a sequence parameter set.

[00122] As an example, the code tree element size for the entire image in the sequence may be set to 128×128. Alternatively, one of the sizes 128×128 or 256×256 may be defined as the size of the image-level code tree element. As an example, the code tree element size in the first image may be set to 128×128, and the code tree element size in the second image may be set to 256×256.

[00123] A code tree element may be split to generate a coding block. The encoding block specifies a base element for encoding or decoding processing. As an example, prediction or transformation may be performed for each encoding block, or a prediction mode may be determined for each encoding block. In this case, the prediction mode indicates a method for generating a prediction image. As an example, the prediction mode may include intra-prediction, inter-picture prediction, current-picture-reference (CPR) (or intra-block copy (IBC)), or combined prediction. A prediction block for a coding block may be generated using at least one prediction mode of intra-prediction, inter-picture prediction, current-picture-locked, or combined prediction for the coding block.

[00124] Information indicating the prediction mode of the current block may be transmitted in a bit stream. As an example, the information may be a 1-bit flag indicating whether the prediction mode is an intra-image mode or an inter-picture mode. Locking to the current image or combined prediction can only be available when it is determined that the prediction mode of the current block is an inter-image mode.

[00125] Linking to the current picture is for setting the current picture as a reference picture and obtaining a current block prediction block from a region of the current picture where encoding or decoding has been performed. In this case, the current image refers to the image containing the current block. Information indicating that the current image anchor applies to the current block may be carried in the bit stream. As an example, the information may be a 1-bit flag. The prediction mode of the current block may be determined to be an anchor to the current image when the flag is true, and the prediction mode of the current block may be determined to be a prediction performed between images when the flag is false. ).

[00126] Alternatively, the prediction mode of the current block may be determined based on the index of the reference image. As an example, when the reference picture index indicates the current picture, it may be determined that the prediction mode of the current block is a reference to the current picture. When the reference picture index points to a picture other than the current picture, it can be determined that the prediction mode of the current block is inter-picture prediction. That is, anchoring to the current image is a prediction method that uses information about a region of the current image where encoding or decoding is performed, and inter-image prediction is a prediction method that uses information about another image where encoding or decoding is performed.

[00127] Combined prediction indicates a coding mode obtained by combining two or more of intra-prediction, inter-picture prediction, and reference to the current picture. As an example, when combined prediction is applied, the first prediction block may be generated based on one of intra-prediction, inter-image prediction, or current image anchoring, and the second prediction block may be generated based on the other. When the first prediction block and the second prediction block are generated, the final prediction block may be generated by an averaging operation or a weighted sum operation between the first prediction block and the second prediction block. Information indicating whether combined prediction is applied may be carried in the bit stream. The information may be a 1-bit flag.

[00128] In FIG. 4 is a schematic diagram showing various types of coding block partitioning.

[00129] A coding block may be partitioned into a plurality of encoding blocks based on a quaternary tree partition, a binary tree partition, or a ternary tree partition. The encoding block obtained by partitioning may be re-partitioned into a plurality of encoding blocks based on a quaternary tree partition, a binary tree partition, or a ternary tree partition.

[00130] Quaternary tree partitioning indicates a partitioning method for partitioning the current block into four blocks. As a result of quaternary tree partitioning, the current block can be divided into four square partitions (see "SPLIT_QT" in Fig. 4A).

[00131] Binary tree partitioning indicates a partitioning method for splitting the current block into two blocks. Splitting the current block into two blocks in the vertical direction (i.e. using a vertical line across the current block) can be called vertical binary tree splitting, and splitting the current block into two blocks in the horizontal direction (i.e. using a horizontal line across the current block) can be called a horizontal binary tree partition. As a result of binary tree partitioning, the current block can be split into two non-square partitions. In fig. 4B "SPLIT_BT_VER" represents the result of vertical splitting based on a binary tree. In fig. 4C "SPLIT_BT_HOR" represents the result of a horizontal split based on a binary tree.

[00132] Ternary tree partitioning specifies a partitioning method for partitioning the current block into three blocks. Splitting the current block into three blocks in the vertical direction (i.e., using two vertical lines across the current block) can be called a vertical ternary tree-based splitting, and splitting the current block into three blocks in the horizontal direction (i.e., using two horizontal lines across the current block) can be called a horizontal ternary tree partition. As a result of ternary tree partitioning, the current block can be partitioned into three non-square partitions. In this case, the width and height of the section located in the center of the current block may be twice as large as the other sections. In fig. 4D "SPLIT_TT_VER" represents the result of a vertical split based on a ternary tree. In fig. 4E "SPLIT_TT_HOR" represents the result of a horizontal split based on a ternary tree.

[00133] The number of times that a code tree element is split can be set as a split depth (split depth). The maximum split depth of a code tree element can be determined at the sequence level or the image level. Thus, the maximum depth of a code tree element may vary depending on the sequence or image.

[00134] Alternatively, the maximum partitioning depth may be determined individually for each partitioning method. As an example, the maximum partition depth allowed for a quaternary tree partition may be different from the maximum partition depth allowed for a binary tree partition and/or a ternary tree partition.

[00135] The encoder may transmit information indicating at least one of a split type or a split depth of the current block in the bitstream. The decoder may determine the split type and split depth of a code tree element based on information parsed from the bit stream.

[00136] In FIG. 5 is a schematic diagram illustrating the partitioning aspect of a code tree element.

[00137] Partitioning a coding block using a partitioning method such as quaternary tree partitioning, binary tree partitioning, and/or ternary tree partitioning may be referred to as multi-tree partitioning.

[00138] Coding blocks generated by applying a multi-tree partition to a coding block may be referred to as lower coding blocks. When the partitioning depth of the encoding block is k, the partitioning depth of the lower encoding blocks is set to k+1.

[00139] Conversely, with respect to coding blocks with partition depth k+1, a coding block with partition depth k may be referred to as an upper encoding block.

[00140] The partition type of the current encoding block may be determined based on at least one of the partition type of the upper encoding block or the partition type of the adjacent encoding block. In this case, the adjacent encoding block is adjacent to the current encoding block and may contain at least one of an adjacent block located above the current encoding block, an adjacent block located to the left of the current encoding block, or an adjacent block adjacent to the upper left corner of the current block coding. In this case, the partition type may include at least one of having a quaternary tree partition, having a binary tree partition, having a binary tree partitioning direction, having a ternary tree partitioning presence, or having a ternary tree partitioning direction.

[00141] For the purpose of determining the type of splitting of the encoding block, information indicating whether the coding block is split may be reported in the bit stream. The information is a 1-bit flag "split_cu_flag", and the flag's value true indicates that the encoding block is split using a multi-tree splitting method.

[00142] When split_cu_flag is true, information indicating whether a coding block is split by a quaternary tree split can be transmitted in the bit stream. The information is a 1-bit flag "split_qt_flag", and when the flag is true, the encoding block can be split into four blocks.

[00143] For example, in FIG. 5 shows that four coding blocks with a partition depth of one are generated because the code tree element is partitioned by quaternary tree partitioning. It is also shown that the quaternary tree partitioning is re-applied to the first encoding block and the fourth encoding block of the four encoding blocks generated by performing the quaternary tree partitioning. As a result, four coding blocks with a partition depth of two can be generated.

[00144] Also, by repeatedly applying the quaternary tree partitioning to a coding block with a partition depth of two, a coding block with a partition depth of three can be generated.

[00145] When quaternary tree partitioning is not applied to the encoding block, then whether to perform binary tree partitioning or ternary tree partitioning on the encoding block can be determined taking into account at least one of the encoding block size , whether the encoding block is located at the edge of the image, the maximum partitioning depth, or the partitioning aspect of an adjacent block. When it is determined that a binary tree partition or a ternary tree partition has been performed on an encoding block, information indicating the direction of partitioning may be transmitted in the bit stream. The information may be a 1-bit mtt_split_cu_vertical_flag. Based on the flag, it can be determined whether the dividing direction is vertical or horizontal. In addition, information indicating which of the binary tree partitioning and the ternary tree partitioning is applied to the encoding block may be transmitted in the bit stream. The information may be a 1-bit mtt_split_cu_binary_flag. Based on the flag, it can be determined whether a binary tree partition or a ternary tree partition is applied to the encoding block.

[00146] As an example, in FIG. 5 shows that a vertical binary tree partition is applied to a coding block with a partition depth of one, a vertical ternary tree partition is applied to the left encoding block from the encoding blocks generated by the vertical binary tree partitioning, and a vertical partitioning on The binary tree base is applied to the right encoding block.

[00147] Because the image is divided into code tree elements, a block that is smaller than a preset size may be present in the area adjacent to the right edge or bottom edge of the image. When a block is assumed to be a code tree element, a code tree element whose size is smaller than a preset size may be generated at the right edge or bottom edge of the image. In this case, the size of the code tree element can be determined based on the information conveyed through the sequence parameter set or the image parameter set.

[00148] In FIG. 6 shows an example in which a block smaller than a code tree element of a predetermined size occurs at the edge of the image.

[00149] When a 1292×1080 image is divided into 128×128 code tree elements, a block smaller than 128×128 is present at the right edge and bottom edge of the image in the example shown in FIG. 6. In the following embodiments, a block smaller than a preset size code tree element occurring at the edge of an image is called an atypical boundary edge block.

[00150] For an atypical boundary edge block, only a predefined partitioning method may be allowed. In this case, the predetermined partitioning method may include at least one of quaternary tree partitioning, ternary tree partitioning, or binary tree partitioning.

[00151] As an example, for an atypical boundary edge block, only quaternary tree-based partitioning may be allowed. In this case, the quaternary tree tiling may be repeated until the block corresponding to the image edge has the minimum quaternary tree tiling size. In this case, the minimum quaternary tree partition size may be preset in the encoder and decoder. Alternatively, information indicating the minimum size of a quaternary tree partition may be carried in the bitstream.

[00152] In FIG. 7 is a schematic diagram showing an example in which quaternary tree partitioning is performed on an atypical boundary edge block. For ease of description, it is assumed that the minimum size of a quaternary tree partition is 4x4.

[00153] An atypical boundary edge block may be divided based on a square block. A square block can be derived from a larger block between the width and height of an atypical boundary edge block. As an example, the exponent of the value 2, which is greater than the reference value and closest to the reference value, can be considered as the length of one side of a square block. As an example, the 12x20 block shown in FIG. 7 may be considered to belong to the 32×32 block, and the partitioning result for the 32×32 block may be applied to the 12×20 block.

[00154] When quaternary tree partitioning is performed on a 12x20 block, the block can be divided into a 12x16 block and a 12x4 block. When quaternary tree partitioning is performed on each of the blocks, a 12x16 block is split into two 8x8 blocks and two 4x8 blocks, and a 12x4 block is split into an 8x4 block and a 4x4 block.

[00155] Quaternary tree partitioning can be performed again on the 4x8 block again located at the edge of the image, and thus two 4x4 blocks can be generated. Similarly, the quaternary tree partitioning can be performed again on the 8x8 block located at the edge of the image, and thus two 4x4 blocks can be generated.

[00156] Alternatively, when at least one of the block width or height is less than or equal to the minimum size of a quaternary tree partition, a binary tree partition may be performed. In this case, the minimum quaternary tree split size may indicate the minimum width of the quaternary tree split or the minimum height of the quaternary tree split. As an example, when the minimum quaternary tree split size is 4x4, the minimum quaternary tree split width and the minimum quaternary tree split height may be 4.

[00157] In this case, a vertical binary tree partitioning may be performed when the block width is less than or equal to the minimum quaternary tree partitioning size, and a horizontal binary tree partitioning may be performed when the block height is less than or equal to the minimum quaternary tree partitioning height. quaternary tree.

[00158] Conversely, quaternary tree partitioning may be performed when the block width or height is greater than the minimum quaternary tree partition size. As an example, when the top right location and bottom left location of a block deviate from the image, and the width or height of the block is larger than the minimum quaternary tree partition size, a quaternary tree partition may be applied to the corresponding block.

[00159] In FIG. 8 is a schematic diagram showing an example in which quaternary tree partitioning is performed on a block adjacent to both the right edge and the bottom edge of the image. For ease of description, it is assumed that the minimum size of a quaternary tree partition is 4x4.

[00160] In the example shown in FIG. 8, when quaternary tree partitioning is performed on a 32x32 block containing a 12x20 block, four 16x16 blocks are generated. Quaternary tree partitioning can be performed again on two 16x16 blocks containing texture data from the generated blocks. As a result, the x-coordinate and y-coordinate may deviate from the edge of the image, and an 8x8 block containing 4x4 texture data can be generated. Since the width and height of an 8x8 block are larger than the minimum size of a quaternary tree partition, a quaternary tree partition can be performed on the corresponding block.

[00161] When quaternary tree partitioning is performed on a 12x20 block, the 12x20 block can be divided into a 12x16 block and a 12x4 block. When the quaternary tree partitioning is performed again on the blocks, the 12x16 block is split into two 8x8 blocks and two 4x8 blocks, and the 12x4 block is split into an 8x4 block and a 4x4 block.

[00162] Since the width of a 4x8 block located at the edge of the image is equal to the minimum size of a quaternary tree partition, a binary tree partition can be performed on the 4x8 block. In detail, vertical binary tree partitioning can be performed based on a square block (ie, 8x8) containing a 4x8 block.

[00163] In addition, since the width of an 8x4 block located at the edge of an image is equal to the minimum size of a quaternary tree partition, a binary tree partition can be performed on the 8x4 block. In detail, horizontal binary tree partitioning can be performed based on a square block (ie, 8x8) containing a 4x8 block.

[00164] As a result of the partitioning, an 8×4 block, a 4×4 block, and a 4×8 block may be located adjacent to the edge of the image.

[00165] Alternatively, when at least one of the block width or height is less than or equal to a threshold value, binary tree-based partitioning may be performed. Otherwise, a partition based on a quaternary tree can be performed. In this case, the threshold value can be obtained based on the minimum partition size based on the quaternary tree. As an example, when the minimum quaternary tree partition size is minQTsize, the threshold value can be set to "minQTsize<<1". Alternatively, information for determining the threshold value may be transmitted separately in the bit stream.

[00166] In FIG. 9 is a schematic view showing a dividing aspect of a block adjacent to an image edge. For ease of description, it is assumed that the minimum size of a quaternary tree partition is 4x4. The threshold value can be set to 8.

[00167] First, a quaternary tree partition may be performed on the 12x20 block. As a result, the block can be split into a 12x16 block and a 12x4 block. Since the width and height of a 12x16 block is greater than the threshold, a quaternary tree partition can be applied to the block. Accordingly, a block can be divided into two 8x8 blocks and two 4x8 blocks.

[00168] The width of the 12×4 block is greater than the threshold value. Accordingly, a quaternary tree-based partitioning can be applied to a 12x4 block. As a result, the block can be split into an 8x4 block and a 4x4 block.

[00169] Subsequently, since the width and height values of the 4x8 block and the 8x4 block located at the edge of the image are less than or equal to the threshold value, binary tree-based partitioning can be applied to the blocks.

[00170] In contrast to the above example, when at least one of the block width or height is greater than the threshold value, binary tree-based partitioning may be performed. Otherwise, a partition based on a quaternary tree can be performed.

[00171] Alternatively, only a quaternary tree partition or a binary tree partition may be applied to the atypical boundary edge block. As an example, a quaternary tree partition may be repeated until a block located at the edge of the image has a minimum size, or a binary tree partition may be repeated until a block located at the edge of the image will have a minimum size.

[00172] An atypical boundary edge block may be specified as an encoding element. Skip mode can be hard-coded on the atypical boundary edge block, or all transform coefficients can be set to 0. Thus, the coded block flag (CBF) value indicating whether the atypical boundary edge block has non-zero transform coefficients can be set to 0 A coding element encoded in skip mode or a coding element having a transform coefficient set to 0 may be called a boundary zero coding element.

[00173] Alternatively, by comparing at least one of the width or height of the encoding block generated by dividing the atypical boundary edge block with a threshold value, it is possible to determine whether to set the corresponding encoding element as a boundary zero encoding element. As an example, a coding block in which at least one of the coding block width or height is less than a threshold value may be encoded in a skip mode, or the transform coefficients may be set to 0.

[00174] In FIG. 10 is a schematic diagram showing an encoding aspect of a block adjacent to an image boundary. The threshold value is assumed to be 8.

[00175] An encoding block in which at least one of the width or height is less than a threshold value, from the encoding blocks generated by splitting the atypical boundary edge block, can be set as a boundary zero encoding element.

[00176] As an example, in the example shown in FIG. 10, a 4x16 coding block, an 8x4 coding block, and a 4x4 coding block can be set as boundary zero coding elements. Accordingly, the blocks may be encoded in skip mode, or the block transform coefficients may be set to 0.

[00177] Whether the skip mode or the transform coefficient is set to 0 may be selectively applied to a coding block having a width and a height that are greater than or equal to a threshold value. For this purpose, a flag indicating whether the skip mode is applied to the encoding block or a flag indicating whether the transform coefficient is set to 0 may be encoded and transmitted.

[00178] Alternatively, only encoding elements generated by binary tree partitioning may be allowed to be set as boundary zero encoding elements. Alternatively, only encoding elements generated by quaternary tree partitioning may be allowed to be set as boundary zero encoding elements.

[00179] Inter-picture prediction is a prediction mode in which the current block is predicted using information about the previous picture. As an example, a block included in the previous image and placed at the same location as the current block (hereinafter referred to as a compatible block) can be set as a prediction block of the current block. A prediction block generated based on a block located at the same location as the current block will be called a compatible prediction block.

[00180] Meanwhile, when an object present in the previous image moves to another location in the current image, the current block can be effectively predicted using the movement of the object. For example, when the motion direction and size of an object can be found by comparing a previous image with a current image, a prediction block (or prediction image) of the current block can be generated taking into account the motion information of the object. Hereinafter, the prediction block generated using the motion information may be called a motion prediction block.

[00181] A residual block may be generated by subtracting a prediction block from a current block. At this time, when motion of the object is present, the energy of the residual block can be reduced, and accordingly, the compression efficiency of the residual block can be improved by using a motion prediction block instead of a fusion prediction block.

[00182] As described above, generating a prediction block using motion information may be called motion-compensated prediction. In inter-image prediction, a prediction block can generally be generated based on the motion compensated prediction.

[00183] The motion information may comprise at least one of a motion vector, a reference image index, a prediction direction, or a bidirectional weight index. The motion vector indicates the direction of motion and the size of the object. The reference picture index indicates the reference picture of the current block of the reference pictures included in the reference picture list. The prediction direction indicates one of unidirectional L0 prediction, unidirectional L1 prediction, or bidirectional prediction (L0 prediction and L1 prediction). At least one of the movement information in the L0 direction or the movement information in the L1 direction may be used depending on the prediction direction of the current block. The bidirectional weight index indicates a weight applied to the L0 prediction block and a weight applied to the L1 prediction block.

[00184] In FIG. 11 is a flowchart of an inter-image prediction method according to an embodiment of the present invention.

[00185] Referring to FIG. 11, the inter-picture prediction method includes determining (S1101) an inter-picture prediction mode of a current block, obtaining (S1102) motion information of the current block according to the determined inter-picture prediction mode, and performing motion compensation prediction (S1102). (S1103) regarding the current block based on the received motion information.

[00186] In this case, an inter-picture prediction mode that represents various methods for determining motion information of the current block may include an inter-picture prediction mode using translational motion information and an inter-picture prediction mode using information about affine motion. As an example, an inter-image prediction mode using translational motion information may include a fusion mode and a motion vector prediction mode, and an inter-image prediction mode using affine motion information may include an affine fusion mode and a vector prediction mode. affine movement. Motion information of the current block can be determined based on information analyzed from the bit stream or blocks adjacent to the current block in accordance with the inter-picture prediction mode.

[00187] An inter-image prediction method using translational motion information will be described in detail below.

[00188] The movement information of the current block can be obtained from the movement information of a block other than the current block. In this case, the other block may be a block that is encoded or decoded by inter-picture prediction earlier than the current block. Setting the motion information of the current block to be the same as the motion information of another block can be set as a merge mode. In addition, setting the motion vector of another block as the motion vector prediction value of the current block can be set as a motion vector prediction mode.

[00189] In FIG. 12 shows a flowchart of the process of obtaining information about the movement of the current block in the merge mode.

[00190] A merge candidate of the current block may be obtained (S1201). The merge candidate of the current block may be obtained from a block that is encoded or decoded by inter-picture prediction earlier than the current block.

[00191] In FIG. 13 is a schematic diagram illustrating candidate blocks used to obtain a merge candidate.

[00192] Candidate blocks may include at least one of adjacent blocks containing a sample adjacent to the current block or non-adjacent blocks containing a sample that is not adjacent to the current block. Next, the samples for determining candidate blocks are set as reference samples. In addition, a reference sample adjacent to the current block will be called an adjacent reference sample, and a reference sample that is not adjacent to the current block will be called a non-adjacent reference sample.

[00193] The adjacent reference sample may be included in a column adjacent to the leftmost column of the current block, or a row adjacent to the top row of the current block. As an example, when the coordinates of the top left sample of the current block are (0, 0), at least one of the block containing the reference sample located at (-1, H-1) of the block containing the reference sample located at (W -1, -1), a block containing a reference sample located at (W, -1), a block containing a reference sample located at (-1, H), or a block containing a reference sample located at (-1, -1), can be used as a candidate block. Referring to the graphics, neighboring blocks with indices 0 to 4 can be used as candidate blocks.

[00194] A non-adjacent reference count indicates a count in which at least one of the x-axis distance or the y-axis distance from a reference count adjacent to the current block has a predetermined value. As an example, at least one of a block containing a reference sample in which an x-axis distance from a left reference sample has a predetermined value, a block containing a non-adjacent sample in which a y-axis distance from an upper reference sample has a predetermined value , or a block containing a non-adjacent sample in which the x-axis distance and the y-axis distance from the top left reference sample have a predetermined value, can be used as a candidate block. The predetermined value may be a natural number, such as 4, 8, 12, and 16. Referring to the drawings, at least one of the blocks with indices 5 to 26 may be used as a candidate block.

[00195] A sample that is not located on the same vertical line, horizontal line, or diagonal line as an adjacent reference sample may be set as a non-adjacent reference sample.

[00196] In FIG. 14 is a schematic diagram showing locations of reference samples.

[00197] As in the example shown in FIG. 14, the x-coordinates of the top non-adjacent reference samples may be set to be different from the x-coordinates of the top adjacent reference samples. As an example, when the location of the top neighbor reference sample is (W-1, -1), the location of the top non-neighbor reference sample located at a distance from the top neighbor reference sample by N along the y-axis is set to ((W/2)-1 , -1-N), and the location of the top non-adjacent reference sample located at a distance of 2N from the top adjacent reference sample in the y-axis can be set to (0, -1-2N). That is, the location of the non-adjacent reference sample can be determined based on the location of the adjacent reference sample and the distance from the adjacent reference sample.

[00198] Hereafter, among the candidate blocks, a candidate block containing an adjacent reference sample will be called an adjacent block, and a block containing a non-adjacent reference sample will be called a non-adjacent block.

[00199] When the distance between the current block and a candidate block is greater than or equal to a threshold value, the candidate block may be set as unavailable as a merge candidate. The threshold value may be determined based on the size of the code tree element. As an example, the threshold may be set equal to the height of the code tree element (ctu_height) or the height of the code tree element plus or minus an offset (eg, ctu_height±N). The offset N, which is a value preset in the encoder or decoder, can be set to 4, 8, 16, 32 or ctu_height.

[00200] When the distance between the y-coordinate of the current block and the y-coordinate of a sample included in the candidate block is greater than a threshold value, it may be determined that the candidate block is not available as a merge candidate.

[00201] Alternatively, a candidate block that does not belong to the same code tree element as the current block may be set as unavailable as a merge candidate. As an example, when the reference sample deviates from the top edge of the code tree element to which the current block belongs, the candidate block containing the reference sample may be set to unavailable as a merge candidate.

[00202] When the top edge of the current block is adjacent to the top edge of a code tree element, it may be determined that a plurality of candidate blocks are not available as merge candidates, and the encoding or decoding efficiency of the current block may be reduced. To solve such a problem, candidate blocks can be set so that the number of candidate blocks located to the left of the current block is greater than the number of candidate blocks located above the current block.

[00203] In FIG. 15 is a schematic diagram illustrating candidate blocks used to obtain a merge candidate.

[00204] As in the example shown in FIG. 15, the top blocks belonging to the N top block columns of the current block and the left blocks belonging to the M left block columns of the current block can be set as candidate blocks. In this case, by setting M greater than N, the number of left candidate blocks can be set to be greater than the number of top candidate blocks.

[00205] As an example, the setting may be made such that the difference between the y-coordinate of the reference sample in the current block and the y-coordinate of the upper block available as a candidate block is not N times the height of the current block. In addition, the setting can be made such that the difference between the x-coordinate of the reference sample in the current block and the x-coordinate of the left block available as a candidate block is not greater than M times the width of the current block.

[00206] As an example, in FIG. 15 shows that blocks belonging to the top two block columns of the current block and blocks belonging to the left five block columns of the current block are set as candidate blocks.

[00207] As another example, when a candidate block does not belong to a sample code tree element as the current block, a merge candidate may be obtained using a block belonging to the same code tree element as the current block or a block containing a reference sample , adjacent to the edge of the code tree element, instead of the candidate block.

[00208] In FIG. 16 is a schematic diagram showing an example in which the location of the reference count is changed.

[00209] When a reference sample is included in a code tree element other than the current block element and is not adjacent to the edge of the code tree element, a candidate block may be determined using a reference sample adjacent to the edge of the code tree element instead of the reference sample.

[00210] As an example, in the examples shown in FIGS. 16A and 16B, when the top edge of the current block is adjacent to the top edge of the code tree element, the reference samples located above the current block belong to a code tree element different from the current block element. A reference sample that is not adjacent to the top edge of a code tree element, from reference samples belonging to a code tree element other than the current block element, may be replaced by a sample adjacent to the top edge of a code tree element.

[00211] For example, the reference sample at location #6 may be replaced with a sample at location #6' placed at the top edge of the code tree element, as in the example shown in FIG. 16A, and the reference sample at location #15 may be replaced by a sample at location #15' placed at the top edge of the code tree element, as in the example shown in FIG. 16B. In this case, the y-coordinate of the alternate sample can be changed to the y-coordinate of a location adjacent to the code tree element, and the x-coordinate of the alternate sample can be set equal to the x-coordinate of the reference sample. As an example, the sample at location #6' may have the same x-coordinate as the sample at location #6, and the sample at location #15' may have the same x-coordinate as the sample at location #15.

[00212] Alternatively, the value obtained by adding or subtracting the offset to the x-coordinate of the reference sample may be set as the x-coordinate of the alternate sample. As an example, when a non-adjacent reference sample and an adjacent reference sample located above the current block have the same x-coordinate, the value obtained by adding or subtracting the offset to the x-coordinate of the reference sample can be set as the x-coordinate of the alternate sample. This is done to prevent an alternate sample replacing a non-adjacent reference sample from being placed in the same location as another non-adjacent reference sample or an adjacent reference sample.

[00213] In FIG. 17 is a schematic diagram showing an example in which the location of the reference count is changed.

[00214] When a reference sample that is included in a code tree element other than the current block element and that is not adjacent to the edge of the code tree element is replaced by a sample located at the edge of the code tree element, the value obtained by adding the offset to the x coordinate reference reading or subtraction from it, can be set as the x-coordinate of the alternate reading.

[00215] As an example, in the example shown in FIG. 17, the reference sample at location #6 and the reference sample at location #15 may be replaced by the sample at location #6' and the sample at location #15', which have the same y-coordinate as the row adjacent to the top edge of the code tree element . In this case, the x-coordinate of the reference at location No. 6' can be set to the value obtained by subtracting W/2 from the x-coordinate of the reference sample at location No. 6, and the x-coordinate of the reference at location No. 15' can be set to the value obtained by subtracting W-1 from the x-coordinate of the reference reading at location #15.

[00216] Unlike the examples shown in FIGS. 16 and 17, the y-coordinate of a row located above the top row of the current block, or the y-coordinate of the top edge of a code tree element, can be set equal to the y-coordinate of the alternate reference.

[00217] Although not shown, a sample replacing the reference sample may be determined based on the left edge of the code tree element. As an example, when the reference sample is not included in the same code tree element as the current block and is not adjacent to the left edge of the code tree element, the reference sample may be replaced by a sample adjacent to the left edge of the code tree element. In this case, the alternate sample may have the same y-coordinate as the reference sample, and may have a y-coordinate obtained by adding the offset to or subtracting the y-coordinate of the reference sample.

[00218] Subsequently, the block containing the alternative sample can be set as a candidate block, and a merge candidate of the current block can be obtained based on the candidate block.

[00219] A merge candidate may be obtained from a temporary neighboring block included in an image other than the current block's image. As an example, a fusion candidate may be obtained from a fusion block included in a fusion image.

[00220] The movement information of the merge candidate may be set equal to the movement information of the candidate block. As an example, at least one of a motion vector, a reference image index, a prediction direction, or a bidirectional weight index of a candidate block may be set as motion information of a fusion candidate.

[00221] A merge candidate list may be generated (S1202) containing the merge candidates. Merge candidates can be divided into contiguous merge candidates obtained from adjacent blocks adjacent to the current block, and non-adjacent merge candidates obtained from non-adjacent blocks.

[00222] Merge candidates from a list of merge candidates may be assigned indices in a predetermined order. As an example, an index assigned to an adjacent merge candidate may have a lower value than an index assigned to a non-adjacent merge candidate. Alternatively, an index may be assigned to each of the merge candidates based on the block indices shown in FIG. 13 or 15.

[00223] When a plurality of merge candidates are included in the merge candidate, at least one of the plurality of merge candidates may be selected (S1203). In this case, information indicating whether movement information of the current block is obtained from an adjacent merge candidate may be transmitted in the bit stream. The information may be a 1-bit flag. As an example, the isAdjancentMergeFlag syntax element, which indicates whether the current block's movement information is derived from an adjacent merge candidate, may be carried in a bit stream. When the value of the isAdjancentMergeFlag syntax element is 1, information about the movement of the current block can be obtained based on the adjacent merge candidate. On the other hand, when the value of the isAdjancentMergeFlag syntax element is 0, information about the movement of the current block can be obtained based on the non-adjacent merge candidate.

[00224] Table 1 shows a syntax table containing the isAdjancentMergeFlag syntax element.

[00225] [Table 1]

[00226] Information to indicate one of a plurality of merge candidates may be transmitted in a bit stream. As an example, information indicating the index of one of the merge candidates included in the list of merge candidates may be transmitted in a bitstream.

[00227] When isAdjacentMergeflag is 1, a merge_idx syntax element may be passed, which is intended to indicate one of the adjacent merge candidates. The maximum value of a merge_idx syntax element can be set to the value obtained by subtracting the element from the number of contiguous merge candidates.

[00228] When isAdjacentMergeflag is 0, a NA_merge_idx syntax element may be passed, which is intended to indicate one of the non-adjacent merge candidates. The NA_merge_idx syntax element represents the value obtained by subtracting the number of contiguous merge candidates from the index of the non-contiguous merge candidate. The decoder may select a non-contiguous merge candidate by adding the number of contiguous merge candidates with the index specified by NA_merge_idx.

[00229] When the number of merge candidates included in the merge candidate list is less than the maximum value, the merge candidate included in the inter-site traffic information table may be added to the merge candidate list. The inter-hop traffic information table may contain a merge candidate obtained based on a block that is encoded or decoded before the current block.

[00230] The inter-section motion information table contains a merge candidate obtained from a block that is encoded or decoded based on the inter-picture prediction in the current picture. As an example, the motion information of a merge candidate included in the inter-section motion information table may be set equal to the motion information of a block encoded or decoded based on inter-picture prediction. In this case, the motion information may comprise at least one of a motion vector, a reference image index, a prediction direction, or a bidirectional weight index.

[00231] For convenience of description, a merge candidate included in the inter-site traffic information table will be referred to as an inter-site merge candidate.

[00232] The maximum number of merge candidates that can be included in the inter-section traffic information table can be preset in the encoder and decoder. As an example, the maximum number of merge candidates that can be included in the inter-site traffic information table may be 1, 2, 3, 4, 5, 6, 7, 8 or more (eg, 16).

[00233] Alternatively, information indicating the maximum number of merge candidates in the inter-section traffic information table may be transmitted in the bit stream. Information can be transferred at the sequence, image or slice level.

[00234] Alternatively, the maximum number of cross-section motion information table merging candidates may be determined depending on the image size, slice size, or code tree element size.

[00235] The inter-section motion information table may be initialized in picture elements, slices, packets, code tree elements, or lines of code tree elements (rows and columns). As an example, when a slice is initialized, the inter-slice traffic information table is also initialized and may not contain a merge candidate.

[00236] Alternatively, information indicating whether the inter-section traffic information table should be initialized may be transmitted in the bit stream. Information can be transferred at the slice, tile, packet or block level. The previously configured inter-leg traffic information table may be used until the information indicates that the inter-leg traffic information table has been initialized.

[00237] Alternatively, information regarding the initial inter-slice fusion candidate may be conveyed by an image parameter set or slice header. Even if the slice is initialized, the inter-slice traffic information table may contain an initial cross-slice merge candidate. Accordingly, an inter-slice merge candidate may be used for the block that is to be encoded or decoded first in the slice.

[00238] Blocks may be encoded or decoded in the encoding or decoding order, and blocks encoded or decoded based on the prediction performed between pictures can be sequentially set as fusion candidates between sections in the encoding or decoding order.

[00239] In FIG. 18 is a schematic diagram for describing an aspect of updating an inter-section traffic information table.

[00240] When inter-picture prediction is performed (S1801) on the current block, an inter-patch fusion candidate can be obtained (S1802) based on the current block. The movement information of a merge candidate between blocks may be set equal to the movement information of the current block.

[00241] When the inter-section traffic information table is empty (S1803), the inter-section merging candidate obtained based on the current block can be added (S1804) to the inter-section traffic information table.

[00242] When the inter-section traffic information table already contains an inter-section merging candidate (S1803), redundancy control may be performed on the movement information of the current block (or the inter-section merging candidate obtained based on the traffic information) (S1805 ). The redundancy check is designed to determine whether the movement information of the current block matches the movement information of an inter-section merger candidate previously stored in the inter-section movement information table. Redundancy checking may be performed on all inter-site merging candidates previously stored in the inter-site traffic information table. Alternatively, redundancy checking may be performed on inter-site merge candidates with indices greater than or equal to a threshold value, or indices less than or equal to a threshold value, from inter-site merge candidates previously stored in the inter-site traffic information table.

[00243] When an inter-picture prediction fusion candidate having the same motion information as the current block is not included, an inter-section fusion candidate obtained based on the current block may be added (S1808) to the motion information table between sites. Whether the inter-image prediction fusion candidates are identical can be determined based on whether the inter-image prediction fusion candidates have the same motion information (eg, motion vector and/or reference image index).

[00244] In this case, when the maximum number of inter-area merging candidates is previously stored in the inter-area traffic information table (S1806), the oldest inter-area merging candidate is deleted (S1807), and the inter-area merging candidate obtained based on current block may be added (S1808) to the inter-section traffic information table.

[00245] Merger candidates between regions can be identified by their indices. When an inter-site merge candidate obtained from the current block is added to the inter-site traffic information table, the smallest index (eg, 0) is assigned to the inter-site merge candidate, and the indices of previously stored inter-site merge candidates may be incremented by one. In this case, when the maximum number of inter-image prediction fusion candidates is previously stored in the inter-site motion information table, the inter-site fusion candidate with the largest index is removed.

[00246] Alternatively, when an inter-site fusion candidate obtained from the current block is added to the inter-site traffic information table, the inter-site fusion candidate may be assigned the largest index. As an example, when the number of prediction fusion candidates carried out between images previously stored in the inter-section motion information table is less than the maximum value, an index having the same value as the number of pre-stored inter-image prediction fusion candidates may be assigned to the inter-section fusion candidate. Alternatively, when the number of prediction fusion candidates carried out between images previously stored in the inter-section motion information table is equal to the maximum value, the inter-section fusion candidate may be assigned an index having a maximum value of minus 1. In addition, the inter-section fusion candidate may be assigned an index having a maximum value of minus 1. In addition, the inter-section fusion candidate The sites with the smallest index are deleted, and the indices of other previously stored merge candidates between sites are decreased by 1.

[00247] In FIG. 19 is a schematic diagram showing an aspect of updating an inter-site merge candidate table.

[00248] Since the inter-site merge candidate obtained from the current block is added to the inter-site merge candidate table, it is assumed that the highest index is assigned to the inter-site merge candidate. It is also assumed that the maximum number of cross-site merge candidates is stored in the cross-site merge candidate table.

[00249] When an inter-site merge candidate HmvpCand[n+1] obtained from the current block is added to the inter-site merge candidate table HmvpCandList, the inter-site merge candidate HmvpCand[0] that has the smallest index of the previously stored candidates for inter-chunk merge can be removed, and the indices of other inter-chunk merge candidates can be reduced by 1. Additionally, the index of the inter-chunk merge candidate HmvpCand[n+1], which is obtained from the current block, can be set as the maximum values (n in the example shown in Fig. 19).

[00250] When an inter-area fusion candidate identical to an inter-area fusion candidate obtained based on the current block is previously stored (S1805), an inter-area fusion candidate obtained based on the current block may not be added (S1809) to the information table about movement between sections.

[00251] Alternatively, while the inter-site fusion candidate obtained based on the current block is added to the inter-site traffic information table, a previously stored inter-site fusion candidate identical to the inter-site fusion candidate may be deleted. This has the same effect as updating the indexes of pre-stored cross-site merge candidates.

[00252] In FIG. 20 is a schematic diagram showing an example in which the index of a previously stored inter-site merge candidate is updated.

[00253] When the index of a previously stored inter-picture prediction fusion candidate that is identical to the mvCand inter-section fusion candidate that is obtained based on the current block is equal to hIdx, the previously stored inter-picture prediction fusion candidate can be deleted. and the indices of inter-image prediction fusion candidates exceeding hIdx may be reduced by 1. As an example, in FIG. 20 shows that HmvpCand[2], which is identical to mvCand, is removed from the inter-section traffic information table HvmpCandList, and that the indices HmvpCand[3] - HmvpCand[n] are reduced by 1.

[00254] In addition, an inter-site fusion candidate mvCand that is obtained based on the current block may be added to the end of the inter-site traffic information table.

[00255] Alternatively, the index assigned to a previously stored inter-partition merge candidate that is identical to the inter-partition merge candidate obtained based on the current block may be updated. For example, the index of a previously stored inter-site merge candidate may be changed to a minimum value or a maximum value.

[00256] The setting may be made such that movement information of blocks included in a predetermined area is not added to the inter-area movement information table. As an example, an inter-site merge candidate obtained based on the movement information of a block included in the parallel merge region may not be added to the inter-site movement information table. Since the encoding or decoding order is not specified for the blocks included in the parallel merging region, it is inappropriate to use the motion information of one of the blocks to perform inter-picture prediction on other blocks. Accordingly, inter-site merge candidates obtained based on blocks included in the parallel merge region may not be added to the inter-site traffic information table.

[00257] When motion-compensated prediction is performed on subblock elements, an inter-region fusion candidate can be obtained based on the motion information of a representative subblock from a plurality of subblocks included in the current block. As an example, when a sub-block merge candidate is used for the current block, the inter-section merge candidate can be obtained based on the motion information of a representative sub-block of the sub-blocks.

[00258] The motion vectors of the sub-blocks can be obtained in the following order. First, one merge candidate may be selected from among the merge candidates included in the list of merge candidates of the current block, and an initial shift vector shVector may be obtained based on the motion vector of the selected merge candidate. Then, a shift subblock having a reference sample located at (xColSb, yColSb) can be obtained by adding the initial shift vector to the location (xSb, ySb) of a reference sample (eg, top left sample or middle sample) of each subblock in the encoding block. Equation 1 below gives the equation to obtain the shift subblock.

[00259] [Equation 1]

[00260] Then, the motion vector of the matching block corresponding to the center position of the subblock containing (xColSb, yColSb) can be set as the motion vector of the subblock containing (xSb, ySb).

[00261] A representative subblock may refer to a subblock containing the top left sample or center sample of the current block.

[00262] In FIG. 21 is a schematic diagram showing the location of a representative subblock.

[00263] In FIG. 21A shows an example in which a subblock located in the upper left corner of the current block is set as a representative subblock, and FIG. 21B shows an example in which a subblock located at the center of the current block is set as a representative subblock. When motion-compensated prediction is performed on subblock elements, a candidate for merging between portions of the current block can be obtained based on the motion vector of the subblock containing the top left sample of the current block or the subblock containing the center sample of the current block.

[00264] Whether to use the current block as an inter-partition fusion candidate can also be determined based on the inter-image prediction mode of the current block. As an example, a block that is encoded or decoded based on an affine motion model may be set as unavailable as a cross-patch fusion candidate. Accordingly, although the current block is encoded or decoded by inter-picture prediction, the inter-picture prediction motion information table may not be updated based on the current block when the inter-picture prediction mode of the current block is an affine prediction mode.

[00265] Alternatively, a cross-section fusion candidate may be obtained based on a subblock vector of at least one subblock included in the block that is encoded or decoded based on the affine motion model. As an example, a cross-section merge candidate may be obtained using a subblock located in the upper left corner of the current block, a subblock located in the center of the current block, or a subblock located in the upper right corner of the current block. Alternatively, the average of the subblock vectors of the plurality of subblocks may be set as the motion vector of the cross-section fusion candidate.

[00266] Alternatively, a cross-patch fusion candidate may be obtained based on the average of the affine source vectors of a block that is encoded or decoded based on the affine motion model. As an example, the average value of at least one of the first affine seed vector, the second affine seed vector, or the third affine seed vector of the current block may be set as the motion vector of the cross-section fusion candidate.

[00267] Alternatively, a table of inter-plot motion information may be configured for each inter-picture prediction mode. As an example, at least one of an inter-lot motion information table for a block encoded or decoded by intra-block copying, an inter-lot motion information table for a block encoded or decoded based on a translational motion model, or an information table may be specified. about the motion between sites for a block encoded or decoded based on an affine motion model. One of the plurality of inter-section motion information tables may be selected according to the inter-picture prediction mode of the current block.

[00268] In FIG. 22 shows an example in which a table of inter-section motion information is generated for each inter-picture prediction mode.

[00269] When a block is encoded or decoded based on a non-affine motion model, an inter-site fusion candidate mvCand that is obtained based on the block may be added to the non-affine inter-site motion information table HmvpCandList. On the other hand, when a block is encoded or decoded based on the affine motion model, the inter-site fusion candidate mvAfCand that is obtained based on the block may be added to the inter-site affine motion information table HmvpAfCandList.

[00270] The affine source vectors of the block may be stored in a cross-section fusion candidate derived from the block that is encoded or decoded based on the affine motion model. Accordingly, the cross-section merge candidate can be used as a merge candidate to obtain the affine source vector of the current block.

[00271] In addition to the inter-section traffic information table described above, an additional inter-section traffic information table may be specified. In addition to the above-described inter-section traffic information table (hereinafter referred to as the first inter-section traffic information table), a long-term traffic information table (hereinafter referred to as the second inter-section traffic information table) may be specified. In this case, the long-term traffic information table contains long-term merge candidates.

[00272] When both the first inter-site traffic information table and the second inter-site traffic information table are empty, inter-site fusion candidates may preferably be added to the second inter-site traffic information table. Until the number of inter-site fusion candidates allowed for the second inter-site traffic information table reaches the maximum number, the inter-site fusion candidates may not be added to the first inter-site traffic information table.

[00273] Alternatively, one inter-image prediction fusion candidate may be added to both the first inter-site motion information table and the second inter-site motion information table.

[00274] In this case, the second inter-section traffic information table where the configuration has been made may no longer be updated. Alternatively, when the decoded region is greater than or equal to the predetermined slice proportion, the second inter-section motion information table may be updated. Alternatively, the second inter-site traffic information table may be updated every N code tree element lines.

[00275] On the other hand, the first inter-section motion information table may be updated whenever a block encoded or decoded by inter-picture prediction is generated. However, the setting may be made such that inter-site fusion candidates added to the second inter-site traffic information table are not used to update the first inter-site traffic information table.

[00276] Information for selecting one of the first inter-area motion information table or the second inter-area motion information table may be transmitted in a bit stream. When the number of merger candidates included in the merger candidate list is less than the maximum value, the merger candidates included in the inter-site traffic information table specified by the information may be added to the merger candidate list.

[00277] Alternatively, the inter-plot motion information table may be selected based on the size, shape or inter-picture prediction mode, the current block, the presence of bidirectional prediction, the presence of motion vector refinement, or the presence of a triangular partition.

[00278] Alternatively, when the number of merger candidates included in the merger candidate list is less than the maximum number associated with the merger, even if the inter-site merger candidates included in the first inter-site traffic information table are added to the candidate list for merging, inter-site merging candidates included in the second inter-site traffic information table may be added to the merging candidate list.

[00279] In FIG. 23 is a schematic diagram showing an example in which a cross-section merging candidate included in the long-term traffic information table is added to the merging candidate list.

[00280] When the number of merge candidates included in the merge candidate list is less than the maximum number, the inter-site merge candidates included in the first inter-site traffic information table HmvpCandList may be added to the merge candidate list. When the number of fusion candidates included in the fusion candidate list is less than the maximum number, even if the inter-site fusion candidates included in the first inter-site traffic information table are added to the fusion candidate list, the inter-site fusion candidates included in long-term traffic information table HmvpLTCandList can be added to the list of merge candidates.

[00281] Table 2 shows the process of adding site fusion candidates included in the long-term traffic information table to the fusion candidate list.

[00282] [Table 2]

[00283] The setting may be made such that the cross-section merging candidate contains additional information as well as motion information. As an example, the size, shape, or block division information may be further stored for a cross-patch merge candidate. When configuring the fusion candidate list for the current block, only inter-image prediction fusion candidates having the same or similar size, shape, or partitioning information as the current block may be used from among the inter-image prediction merging candidates, or Prediction fusion candidates performed between images having the same or similar size, shape, or partition information as the current block may preferably be added to the fusion candidate list.

[00284] Alternatively, a table of inter-section movement information may be generated for each size, shape, or piece of block division information. A list of merge candidates of the current block may be generated using an inter-section traffic information table corresponding to the shape, size, or division information of the current block from a plurality of inter-section traffic information tables.

[00285] Alternatively, a table of inter-site motion information can be created for each motion vector resolution. As an example, when the motion vector of the current block has a resolution of 1/4 pixel, an inter-region fusion candidate obtained from the current block may be added to the inter-region motion information list with a resolution of a quarter pixel. When the motion vector of the current block has a resolution of 1 whole pixel, the inter-region fusion candidate obtained from the current block can be added to the list of inter-region motion information of the full pixel resolution. When the motion vector of the current block has a resolution of 4 whole pixels, the inter-region fusion candidate obtained from the current block can be added to the list of inter-region motion information with a resolution of 4 whole pixels. One of a plurality of inter-section motion information lists may be selected in accordance with the motion vector resolution of the block to be encoded or decoded.

[00286] When the fusion offset vector encoding method is applied to the current block, the inter-section fusion candidate obtained from the current block may be added to the inter-section fusion offset movement information list HmvpHMVDCandList instead of adding to the inter-section movement information table HmvpCandList. In this case, the cross-section fusion candidate may contain motion vector offset information of the current block. HmvpHMVDCandList can be used to obtain the offset of the block to which the merge offset vector encoding method is applied.

[00287] When the number of merge candidates included in the merge candidate list of the current block is not equal to the maximum value, the inter-site merge candidate included in the inter-site traffic information table may be added to the merge candidate list. The adding process can be performed in ascending or descending order based on indices. As an example, a cross-region merge candidate with the highest index may be preferably added to the merge candidate list.

[00288] When an inter-site merging candidate included in the inter-site traffic information table is to be added to the merging candidate list, redundancy check can be performed between the inter-site merging candidate and the merging candidates previously stored in the candidate list. for the merger.

[00289] As an example, Table 3 shows the process of adding a cross-site merge candidate to the merge candidate list.

[00290] [Table 3]

[00291] Redundancy checking can only be performed on some inter-site merging candidates included in the inter-site traffic information table. As an example, redundancy checking may be performed only on merge candidates between regions with indices greater than or equal to a threshold value, or indices less than or equal to a threshold value.

[00292] Alternatively, redundancy checking may be performed only on some of the merge candidates previously stored in the merge candidate list. As an example, redundancy checking may be performed only on a merge candidate with an index greater than or equal to a threshold, or an index less than or equal to the threshold, or a merge candidate obtained from a block at a particular location. In this case, the particular location may include at least one of a left neighbor block, a top neighbor block, a top right neighbor block, or a bottom left neighbor block of the current block.

[00293] In FIG. 24 is a schematic diagram showing an example in which redundancy checking is performed only on some merge candidates.

[00294] When the inter-site merge candidate HmvpCand[j] is to be added to the list of merge candidates, a redundancy check may be performed on the inter-site merge candidate regarding the two merge candidates mergeCandList[NumMerge-2] and mergeCandList[ NumMerge -1], having the largest indices. In this case, NumMerge can represent the number of available spatial merge candidates and temporal merge candidates.

[00295] When a fusion candidate identical to the first inter-site fusion candidate is found, a redundancy check with respect to the fusion candidate identical to the first inter-site fusion candidate may be skipped while a redundancy check with respect to the second inter-site fusion candidate merging between sections is performed.

[00296] In FIG. 25 is a schematic diagram showing an example in which redundancy checks are omitted with respect to a particular merger candidate.

[00297] When the inter-site merge candidate HmvpCand[i] with index i is to be added to the merge candidate list, redundancy checking can be performed between the inter-site merge candidate and the merge candidates previously stored in the merge candidate list. In this case, when a merge candidate mergeCandList[j] is found identical to the inter-site merge candidate HmvpCand[i], the inter-site merge candidate HmvpCand[i] may not be added to the merge candidate list, and redundancy checking may be performed between the fusion candidate between the sites HmvpCand[i-1] having index i-1 and the fusion candidates. In this case, the redundancy check between the cross-section merge candidate HmvpCand[i-1] and the merge candidate mergeCandList[j] may be skipped.

[00298] As an example, in the example shown in FIG. 25, it is determined that HmvpCand[i] and mergeCandList[2] are identical to each other. Accordingly, HmvpCand[i] may not be added to the merge candidate list, and redundancy checking may be performed on HmvpCand[i-1]. In this case, the redundancy check between HvmpCand[i-1] and mergeCandList[2] may be skipped.

[00299] When the number of merge candidates included in the list of merge candidates of the current block is less than the maximum number, at least one of the paired merge candidate or the null merge candidate may be further included in addition to the inter-block merge candidate . A pairwise fusion candidate refers to a fusion candidate with a motion vector equal to the average of the motion vectors of two or more fusion candidates, and a null fusion candidate refers to a fusion candidate with a motion vector equal to 0.

[00300] A merge candidate may be added to the list of merge candidates of the current block in the following order.

[00301] Spatial merge candidate - Temporal merge candidate - Inter-site merge candidate - (Affine inter-site merge candidate) - Pairwise merge candidate - Null merge candidate.

[00302] A spatial merge candidate refers to a merge candidate obtained from at least one of an adjacent block or a non-neighboring block, and a temporal merge candidate refers to a merge candidate obtained from a previous reference image. An inter-region affine fusion candidate refers to an inter-region fusion candidate obtained from a block encoded or decoded by an affine motion model.

[00303] The inter-section motion information table can be used even in motion vector prediction mode. As an example, when the number of motion vector prediction candidates included in the motion vector prediction candidate list of the current block is less than the maximum number, an inter-section fusion candidate included in the inter-section motion information table may be set as a motion vector prediction candidate for the current block. In detail, the motion vector of the cross-section fusion candidate can be set as the motion vector prediction candidate.

[00304] When one of the motion vector prediction candidates included in the motion vector prediction candidate list of the current block is selected, the selected candidate may be set as the motion vector predictor of the current block. Subsequently, the motion vector of the current block can be obtained by decoding the residual motion vector value of the current block and then adding the motion vector predictor and the residual motion vector value.

[00305] The motion vector prediction candidate list of the current block may be configured in the following order.

[00306] Spatial motion vector prediction candidate - Temporal motion vector prediction candidate - Inter-picture decoding domain fusion candidate - (Inter-picture decoding domain affine fusion candidate) - Null motion vector prediction candidate.

[00307] A spatial motion vector prediction candidate refers to a motion vector prediction candidate obtained from at least one of an adjacent block or a non-neighboring block, and a temporal motion vector prediction candidate refers to a motion vector prediction candidate obtained from a previous reference picture. An inter-region affine fusion candidate refers to an inter-region motion vector prediction candidate obtained from a block encoded or decoded by an affine motion model. The null motion vector prediction candidate represents a candidate having a motion vector equal to 0.

[00308] The merge processing area may be set to be larger than the encoding block size. Encoding blocks included in the merge processing area can be processed in parallel without sequential encoding or decoding. In this case, inconsistent encoding or decoding means that the order of encoding or decoding is not specified. Accordingly, the encoding or decoding process of blocks included in the merge processing area can be processed independently. Alternatively, blocks included in the merge processing area may share merge candidates. In this case, merge candidates can be obtained based on the merge processing area.

[00309] According to the above-described characteristics, the merge processing region may be called a parallel processing region, a shared merge region (SMR), or a merge evaluation region (MER).

[00310] A merge candidate of the current block may be obtained based on the encoding block. However, when the current block is included in a parallel merge region larger than the current block, a candidate block included in the same parallel merge region as the current block may be set as unavailable as a merge candidate.

[00311] In FIG. 26 is a schematic diagram showing an example in which a candidate block included in the same parallel merge region as the current block is set to unavailable as a merge candidate.

[00312] In the example shown in FIG. 26A, when CU5 is encoded or decoded, blocks containing reference samples adjacent to CU5 may be set as candidate blocks. In this case, candidate blocks X3 and X4, which are included in the same parallel merge area as CU5, may be set as unavailable as merge candidates. On the other hand, candidate blocks X0, X1 and X2, which are not included in the same parallel merge area as CU5, can be set as available as merge candidates.

[00313] In the example shown in FIG. 26B, when CU8 is encoded or decoded, blocks containing reference samples adjacent to CU8 may be set as candidate blocks. In this case, candidate blocks X6, X7 and X8, which are included in the same parallel merge area as CU8, may be set as unavailable as merge candidates. On the other hand, candidate blocks X5 and X9, which are not included in the same merge area as CU8, can be set as available as merge candidates.

[00314] The parallel merge region may be square or non-square. Information for defining the parallel merge area may be transmitted in a bit stream. The information may comprise at least one of information indicating the shape of the parallel merge region or information indicating the size of the parallel merge region. When the parallel merge area is not square, at least one of information indicating the size of the parallel merge area, information indicating the width and/or height of the parallel merge area, or information indicating the ratio between the width and height of the parallel merge area may be transmitted to bit stream.

[00315] The size of the parallel merge region may be determined based on at least one of information carried in the bit stream, image resolution, slice size, or tile size.

[00316] When motion compensation prediction is performed on a block included in a parallel fusion region, an inter-section fusion candidate obtained based on the motion information of the block subject to motion compensation prediction may be added to the inter-section motion information table.

[00317] However, when an inter-site merge candidate obtained from a block included in a parallel merge area is added to the inter-site traffic information table, an inter-site merge candidate obtained from the block can be used when another block included in the parallel merge region is actually encoded or decoded later than this block. That is, although the dependence between blocks must be eliminated when encoding or decoding blocks included in the parallel merge region, motion prediction compensation can be performed using motion information of another block included in the parallel merge region. In order to solve this problem, even if encoding or decoding of a block included in the parallel merge area is performed, motion information of the block in which encoding or decoding is performed may not be added to the inter-section motion information table.

[00318] Alternatively, when motion-compensated prediction is performed on blocks included in a parallel fusion region, an inter-site fusion candidate obtained from the blocks may be added to the inter-site motion information table in a predetermined order. In this case, a predetermined order may be determined in the scanning order of coding blocks in a code tree element or a parallel merge region. The scanning order may be at least one of raster scanning, horizontal scanning, vertical scanning, or zigzag scanning. Alternatively, the predetermined order may be determined based on the motion information of each of the blocks or the number of blocks having the same motion information.

[00319] Alternatively, an inter-site merge candidate containing unidirectional traffic information may be added to the inter-site merge list before an inter-site merge candidate containing bidirectional traffic information. Conversely, an inter-site fusion candidate containing bidirectional traffic information may be added to the list of inter-site fusion candidates earlier than an inter-site fusion candidate containing unidirectional traffic information.

[00320] Alternatively, inter-site fusion candidates may be added to the inter-site traffic information table in ascending or descending order of frequency of use in the parallel merge region or code tree element.

[00321] When the current block is included in the parallel merge area, and the number of merge candidates included in the current block's merge candidate list is less than the maximum number, the inter-site merge candidate included in the inter-site traffic information table may be added to list of merger candidates. In this case, the setting may be made such that a cross-section merge candidate obtained from a block included in the same parallel merge region as the current block is added to the list of merge candidates of the current block.

[00322] Alternatively, the setting may be made such that when the current block is included in the parallel merge region, the inter-site merge candidate included in the inter-site traffic information table is not used. That is, even when the number of merge candidates included in the merge candidate list of the current block is less than the maximum number, the inter-site merge candidate included in the inter-site traffic information table may not be added to the merge candidate list.

[00323] An inter-region traffic information table may be configured for a parallel merge region or code tree element. This inter-section movement information table serves to temporarily store movement information of blocks included in the parallel merge area. To distinguish the general inter-site motion information table from the inter-site motion information table for a parallel merge region or code tree element, the inter-site motion information table for a parallel merge region or code tree element will be referred to as a temporary motion information table. In addition, the cross-section merge candidate stored in the temporary traffic information table will be called a temporary merge candidate.

[00324] In FIG. 27 is a schematic diagram showing a temporary motion information table.

[00325] A temporary motion information table may be configured for a code tree element or a parallel merge region. When motion compensation prediction is performed on a current block included in a code tree element or a parallel merge region, motion information of the block may not be added to the inter-picture prediction motion information table HmvpCandList. Instead, the temporary merge candidate obtained from the block may be added to the temporary traffic information table HmvpMERCandList. That is, a temporary merge candidate added to the temporary traffic information table may not be added to the inter-section traffic information table. Accordingly, the inter-section motion information table may not contain an inter-site merge candidate derived from the motion information of blocks included in the parallel merge region or the code tree element containing the current block.

[00326] The maximum number of merge candidates that can be included in the temporary traffic information table can be set to the same as that in the inter-section traffic information table. Alternatively, the maximum number of merge candidates that can be included in the temporary motion information table can be determined according to the size of the code tree element or the parallel merge region.

[00327] A current block included in a code tree element or parallel merge region may be set so as not to use a temporary motion information table for the corresponding code tree element or corresponding parallel merge region. That is, when the number of merge candidates included in the merge candidate list of the current block is less than the maximum value, the inter-section merge candidate included in the inter-section traffic information table may be added to the merge candidate list, and temporary A merge candidate included in the temporary motion information table may not be added to the merge candidate list. Accordingly, motion information of other blocks included in the same code tree element or parallel merge region as the current block may not be used for motion-compensated prediction of the current block.

[00328] When performing encoding or decoding of all blocks included in a code tree element or a parallel merge area, the inter-section motion information table and the temporary motion information table can be merged.

[00329] In FIG. 28 is a schematic diagram showing an example of merging a temporary motion information table with an inter-section motion information table.

[00330] When performing encoding or decoding of all blocks included in a code tree element or a parallel merge region, the inter-section motion information table may be updated with a temporary merge candidate included in the temporary motion information table, in the example shown in fig. 28.

[00331] In this case, the temporary merge candidates included in the temporary traffic information table may be added to the inter-site traffic information table in the order in which the temporary merge candidates were inserted into the temporary traffic information table (i.e. i.e. in ascending or descending order of index values).

[00332] As another example, temporary merge candidates included in the temporary traffic information table may be added to the inter-section traffic information table in a predetermined order.

[00333] In this case, a predetermined order may be determined in the scanning order of coding blocks in a code tree element or a parallel merge region. The scanning order may be at least one of raster scanning, horizontal scanning, vertical scanning, or zigzag scanning. Alternatively, the predetermined order may be determined based on the motion information of each of the blocks or the number of blocks having the same motion information.

[00334] Alternatively, a temporary merge candidate containing unidirectional traffic information may be added to the inter-site merge list before a temporary merge candidate containing bidirectional traffic information. Conversely, a temporary merge candidate containing bidirectional traffic information may be added to the inter-site merge candidate list earlier than a temporary merge candidate containing unidirectional traffic information.

[00335] Alternatively, temporary merge candidates may be added to the inter-site traffic information table in ascending or descending order of frequency of use in the parallel merge region or code tree element.

[00336] When a temporary merge candidate included in the temporary traffic information table is added to the inter-section traffic information table, redundancy checking for the temporary merge candidate can be performed. As an example, when an inter-area merging candidate identical to a temporary merging candidate included in the temporary traffic information table is previously stored in the inter-site traffic information table, the temporary merging candidate may not be added to the inter-site traffic information table. In this case, redundancy checking can only be performed on some inter-site merging candidates included in the inter-site traffic information table. As an example, redundancy checking may be performed only on inter-image prediction fusion candidates with indices greater than or equal to a threshold, or indices less than or equal to a threshold. As an example, when the temporary merge candidate is identical to the inter-site merge candidate with an index greater than or equal to a predetermined value, the temporary merge candidate may not be added to the inter-site traffic information table.

[00337] Intra prediction is designed to predict the current block using a reconstructed sample that has been encoded or decoded and that is adjacent to the current block. In this case, the reconstructed sample before applying the filter in the loop can be used for intra-prediction of the current block.

[00338] The intra prediction method includes matrix-based intra prediction and directivity-based normal intra prediction with respect to the nearest reconstructed sample. Information indicating the intra prediction method of the current block may be carried in the bit stream. The information may be a 1-bit flag. Alternatively, the intra prediction method of the current block may be determined based on at least one of the location, size or shape of the current block or the intra prediction method of an adjacent block. As an example, when the current block is present at the edge of the image, the setting may be made such that the matrix-based intra prediction is not applied to the current block.

[00339] Matrix-based intra prediction may be a method of deriving a block prediction of a current block based on a matrix product between a matrix previously stored in the encoder and decoder and reconstructed samples adjacent to the current block. Information to indicate one of a plurality of pre-stored matrices may be transmitted in a bit stream. The decoder may determine a matrix for intra prediction of the current block based on the information and size of the current block.

[00340] Normal intra prediction is a method of obtaining a prediction block for a current block based on an undirected intra prediction mode or a directed intra prediction mode. The process of performing intra prediction based on normal intra prediction will be described in detail below with reference to drawings.

[00341] In FIG. 29 is a flowchart of an intra prediction method according to an embodiment of the present invention.

[00342] The reference sample line of the current block can be determined (S2901). A reference sample line refers to a set of reference samples included in the kth line from the top and/or left side of the current block. The reference samples can be obtained from the reconstructed samples that have been encoded or decoded and are adjacent to the current block.

[00343] Index information for identifying a reference sample line of a current block from a plurality of reference sample lines may be transmitted in a bit stream. The plurality of reference sample lines may comprise at least one of a first line, a second line, a third line, or a fourth line from above and/or to the left of the current block. Table 4 presents the indices assigned to the reference reference lines. Table 4 assumes that the first line, second line, and fourth line are used as reference sample line candidates.

[00344] [Table 4]

[00345] The reference line of the current block may be determined based on at least one of the location, size or shape of the current block or the prediction mode of the neighboring block. As an example, when the current block is adjacent to the edge of an image, tile, slice, or code tree element, the first reference sample line of the current block may be defined as the reference sample line of the current block.

[00346] The reference sample line may include top reference samples located above the current block and left reference samples located to the left of the current block. The top reference samples and left reference samples can be obtained from the reconstructed samples adjacent to the current block. The reconstructed samples may be in the state before the filter was applied to the loop.

[00347] In FIG. 30 is a schematic diagram showing reference samples included in each reference sample line.

[00348] A prediction sample may be obtained using at least one reference sample belonging to a reference sample line in accordance with the intra prediction mode of the current block.

[00349] Next, the intra prediction mode of the current block can be determined (S2902). At least one of an undirected intra prediction mode or a directed intra prediction mode may be determined as the intra prediction mode of the current block. The non-directional intra prediction mode includes planar mode and DC mode, and the directional intra prediction mode includes 33 or 65 modes from diagonal down and left direction to diagonal up and right direction.

[00350] In FIG. 31 is a schematic diagram showing intra prediction modes.

[00351] In FIG. 31A shows 35 intra prediction modes, and FIG. 31B shows 67 intra prediction modes.

[00352] More intra prediction modes or fewer intra prediction modes may be specified than shown in FIG. 31.

[00353] The most probable mode (MPM) can be set based on the intra prediction mode of a block adjacent to the current block. Here, the neighbor block may include a left neighbor block adjacent to the left side of the current block and an upper neighbor block adjacent to the top side of the current block. When the coordinates of the top left sample of the current block are (0, 0), the left adjacent block may include the sample located at (-1, 0), (-1, H-1) or (-1, (H-1)/2 ). In this case, H represents the height of the current block. The upper adjacent block may include a sample located at (0, -1), (W-1, -1) or ((W-1)/2, -1). In this case, W represents the width of the current block.

[00354] When a neighboring block is encoded using normal intra prediction, the MPM can be obtained based on the intra prediction mode of the neighboring block. In detail, the intra prediction mode of the left neighbor block can be set using the variable candIntraPredModeA, and the intra prediction mode of the top neighbor block can be set using the variable candIntraPredModeB.

[00355] In this case, when a neighboring block is not available (for example, when a neighboring block has not yet been encoded or decoded, or when the location of a neighboring block deviates from the edge of the image), when the neighboring block is encoded using matrix-based intra prediction, when the neighboring block is encoded using inter-picture prediction, or when a neighboring block is included in a code tree element other than the current block element, the default mode can be set to the candIntraPredModeX variable (in this case X represents A or B) derived from neighboring block intra prediction mode. Here, the default mode may include at least one of a planar mode, a DC mode, a vertical mode, or a horizontal mode.

[00356] Alternatively, when a neighboring block is encoded using matrix-based intra prediction, the intra prediction mode corresponding to the index value for indicating one of the plurality of matrices can be set to candIntraPredModeX. For this purpose, a lookup table indicating the mapping relationship between intra prediction modes and index values for specifying matrices may be previously stored in the encoder and decoder.

[00357] MPMs can be obtained based on the candIntraPredModeA variable and the candIntraPredModeB variable. The number of MPMs included in the MPM list can be preset in the encoder and decoder. As an example, the number of MPMs may be three, four, five or six. Alternatively, information indicating the number of MPMs may be transmitted in the bit stream. Alternatively, the number of MPMs may be determined based on at least one of a neighboring block prediction mode or the size or shape of the current block.

[00358] In the following embodiments, the number of MPMs is assumed to be three, and the three MPMs are called MPM[0], MPM[1], and MPM[2]. When the number of MRMs is greater than three, the MRMs may be configured to include three MRMs, which will be described in the following embodiments.

[00359] When candIntraPredA and candIntraPredB are identical, and candIntraPredA is planar mode or DC mode, MPM[0] and MPM[1] can be set for planar mode and DC mode, respectively. MPM[2] can be set for vertical intra prediction mode, horizontal intra prediction mode, or diagonal intra prediction mode. The diagonal intra prediction mode may be a diagonal down-left intra prediction mode, an up-left intra prediction mode, or an up-right intra prediction mode.

[00360] When candIntraPredA and candIntraPredB are identical, and candIntraPredA is a directed intra prediction mode, MPM[0] can be set to be identical to candIntraPredA. MPM[1] and MPM[2] can be set for intra prediction modes like candIntraPredA. An intra prediction mode like candIntraPredA may be an intra prediction mode in which the index difference value with respect to candIntraPredA is ±1 or ±2. Modulo (%) and offset operations can be used to obtain an intra prediction mode similar to candIntraPredA.

[00361] When candIntraPredA and candIntraPredB are different, MPM[0] can be set to be identical to candIntraPredA, and MPM[1] can be set to be identical to candIntraPredB. In this case, when both candIntraPredA and candIntraPredB are non-directional intra prediction modes, MPM[2] can be set as a vertical intra prediction mode, a horizontal intra prediction mode, or a diagonal intra prediction mode. Alternatively, when at least one of candIntraPredA and candIntraPredB is a directional intra prediction mode, MPM[2] may be set to be the intra prediction mode obtained by adding an offset to or subtracting the planar mode, DC mode, or greater of candIntraPredA and candIntraPredB . In this case, the offset can be 1 or 2.

[00362] An MPM list containing a plurality of MPMs is created, and information indicating whether an MPM identical to the intra prediction mode of the current block is included in the MPM list may be transmitted in the bit stream. The information is a 1-bit flag, and the flag may be called an MPM flag. When the MPM flag indicates that an MPM identical to the current block is included in the MPM list, index information to indicate one of the MPMs may be transmitted in the bit stream. The intra prediction mode of the current block may be set to the MPM indicated by the index information. When the MPM flag indicates that an MPM identical to the current block is not included in the MPM list, residual mode information indicating one of the remaining intra prediction modes other than MPM may be transmitted in the bit stream. The residual mode information indicates an index value corresponding to the intra prediction mode of the current block when the indexes are reassigned to the remaining intra prediction modes other than MPM. To determine the intra prediction mode of the current block, the decoder may sort the MPM in ascending order and compare the MPM with the residual mode information. As an example, when the residual mode information is less than or equal to MPM, the intra prediction mode of the current block can be obtained by adding one to the residual mode information.

[00363] Instead of setting MPM as the default mode, information indicating whether the intra prediction mode of the current block is the default mode may be carried in the bitstream. The information may be a 1-bit flag, and the flag may be called a default mode flag. The default mode flag can be passed only when the MPM flag indicates that an MPM identical to the current block is included in the MPM list. As described above, the default mode may include at least one of planar mode, DC mode, vertical mode, or horizontal mode. As an example, when the default mode is set to planar mode, the default mode flag may indicate whether the intra prediction mode of the current block is planar mode. When the default mode flag indicates that the intra prediction mode of the current block is not the default mode, the intra prediction mode of the current block may be set to one of the MPMs indicated by the index information.

[00364] When multiple intra prediction modes are set as default modes, index information indicating one of the default modes may be transmitted. The intra prediction mode of the current block can be set as the default mode indicated by the index information.

[00365] When the index of the reference sample line of the current block is non-zero, the setting can be made such that the default mode is not used. Accordingly, when the index of the reference sample line is non-zero, the default mode flag may not be transmitted, and the value of the default mode flag may be set to a preset value (ie, false).

[00366] When the intra prediction mode of the current block is determined, prediction samples for the current block can be obtained (S2903) based on the determined intra prediction mode.

[00367] When the DC mode is selected, prediction samples for the current block can be generated based on the average of the reference samples. In detail, the values of all samples in the prediction block may be generated based on the average value of the reference samples. The average may be obtained using at least one of the top reference samples located above the current block and the left reference samples located to the left of the current block.

[00368] The number or range of reference samples used to obtain the average may vary depending on the shape of the current block. As an example, when the current block is a non-square block in which the width is greater than the height, the average can be calculated using only the top reference samples. On the other hand, when the current block is a non-square block in which the width is less than the height, the average can be calculated using only the left reference samples. That is, when the width and height of the current block are different from each other, the average can be calculated using only the reference samples adjacent to the larger of the width and height. Alternatively, whether to calculate the average using the top reference samples or calculate the average using the left reference samples can be determined based on the width-to-height ratio of the current block.

[00369] When the planar mode is selected, a prediction sample can be obtained using a horizontal prediction sample and a vertical prediction sample. In this case, the horizontal prediction sample is obtained based on the left reference sample and the right reference sample located on the same horizontal line as the prediction sample, and the vertical prediction sample is obtained based on the upper reference sample and the lower reference sample located on the same vertical line , which is the prediction count. Here, the right reference sample may be generated by copying a reference sample adjacent to the upper right corner of the current block, and the lower reference sample may be generated by copying the reference sample adjacent to the lower left corner of the current block. The horizontal prediction count can be obtained based on the weighted sum operation of the left reference sample and the right reference sample, and the vertical prediction count can be obtained based on the weighted sum operation of the upper reference sample and the lower reference sample. In this case, the weight assigned to each reference sample can be determined depending on the location of the prediction sample. The prediction sample may be obtained based on an averaging operation or a weighted sum operation of the horizontal prediction sample and the vertical prediction sample. When performing the weighted sum operation, weights assigned to the horizontal prediction sample and the vertical prediction sample can be determined based on the location of the prediction sample.

[00370] When a directional prediction mode is selected, a parameter indicating the prediction direction (or prediction angle) of the selected directional prediction mode can be determined. Table 5 below presents the intraPredAng intra direction parameter for each intra prediction mode.

[00371] [Table 5]

[00372] Table 5 shows the intra direction parameter for each intra prediction mode with an index from 2 to 34 when 35 intra prediction modes are specified. When more than 33 directional intra prediction modes are specified, Table 5 can be subdivided to set the intra direction parameters for each directional intra prediction mode.

[00373] After arranging the top reference samples and the left reference samples of the current block in a line, a prediction sample can be obtained based on the value of the inner direction parameter. In this case, the left reference samples and the top reference samples can be arranged in a line when the value of the inner direction parameter is negative.

[00374] In FIG. 32 and 33 are schematic diagrams showing an example of a one-dimensional array in which reference samples are arranged in a line.

[00375] In FIG. 32 shows an example of a one-dimensional vertical array in which the reference samples are located vertically, and FIG. Figure 33 shows an example of a one-dimensional horizontal array in which the reference samples are located horizontally. The embodiments shown in FIGS. 32 and 33 will be described assuming that 35 intra prediction modes are specified.

[00376] A one-dimensional horizontal array, in which the top reference samples are rotated counterclockwise, may be used when the intra prediction mode index is between 11 and 18, and a one-dimensional vertical array, in which the left reference samples are rotated clockwise, may be the case when the intra prediction mode index is between 19 and 25. When the reference samples are arranged in a line, the intra prediction mode angle can be taken into account.

[00377] Based on the internal direction parameter, a reference count determination parameter can be determined. The reference sample determination parameter may comprise a reference sample index to indicate the reference sample and a weight parameter to determine the weight to be applied to the reference sample.

[00378] The reference index iIdx and the weighting parameter ifact can be obtained using Equations 2 and 3 below.

[00379] [Equation 2]

[00380] [Equation 3]

[00381] In Equations 2 and 3, Pang represents the internal direction parameter. The reference sample, indicated by the reference sample index iIdx, corresponds to an integer pixel.

[00382] At least one reference sample may be specified to obtain the prediction sample. In detail, the location of the reference sample to be used in obtaining the prediction sample may be specified taking into account the slope of the prediction mode. As an example, a reference sample to use in obtaining a prediction sample may be specified using the reference sample index iIdx.

[00383] In this case, when the slope of the intra prediction mode cannot be expressed by a single reference sample, the prediction sample can be generated by interpolating multiple reference samples. As an example, when the slope of the intra prediction mode is a value between the slope between the prediction sample and the first reference sample and the slope between the prediction sample and the second reference sample, the prediction sample can be obtained by interpolating the first reference sample and the second reference sample. That is, the corner line corresponding to the intra prediction angle does not pass through a reference sample located in the entire pixel, the prediction sample can be obtained by interpolating the reference samples adjacent to the left, right, top or bottom sides of the location through which the corner line passes.

[00384] Below, Equation 4 shows an example of obtaining a prediction sample based on the reference samples.

[00385] [Equation 4]

[00386] In Equation 4, P represents a prediction sample, and Ref_1D represents one of the reference samples located in one dimension. In this case, the location of the reference sample can be determined from the reference sample index iIdx and the location (x, y) of the prediction sample.

[00387] When the slope of the intra prediction mode can be expressed by a single reference sample, the weight parameter ifact can be set to zero. Accordingly, Equation 4 can be simplified to Equation 5 below.

[00388] [Equation 5]

[00389] Intra prediction may be performed on the current block based on a variety of intra prediction modes. As an example, an intra prediction mode may be obtained for each prediction sample, and a prediction sample may be obtained based on the intra prediction mode assigned to the corresponding prediction sample.

[00390] Alternatively, an intra prediction mode may be obtained for each region, and intra prediction may be performed on the corresponding region based on the intra prediction mode assigned to the corresponding region. In this case, the region may contain at least one sample. At least one of the size or shape of the region may be adaptively determined based on at least one of the size, shape, or intra prediction mode of the current block. Alternatively, at least one of the size or shape of the region may be preset in the encoder and decoder regardless of the size or shape of the current block.

[00391] Alternatively, intra prediction may be performed multiple times, and the final prediction sample may be obtained based on an averaging operation or a weighted sum operation of multiple prediction samples obtained by performing intra prediction multiple times. As an example, a first prediction sample may be obtained by performing intra prediction based on a first intra prediction mode, and a second prediction sample may be obtained by performing intra prediction based on a second intra prediction mode. Then, the final prediction sample can be obtained based on an averaging operation or a weighted sum operation of the first prediction sample and the second prediction sample. In this case, the weights assigned to the first prediction sample and the second prediction sample may be determined taking into account at least one of whether the first intra prediction mode is an undirected prediction mode or a directional prediction mode, whether the second intra prediction mode is a undirected prediction or directed prediction mode, or intra-neighbor block prediction mode.

[00392] The plurality of intra prediction modes may be a combination of an undirected intra prediction mode and a directed intra prediction mode, a combination of directed intra prediction modes, or a combination of undirected intra prediction modes.

[00393] In FIG. 34 is a schematic view illustrating the angles formed between a straight line parallel to the x-axis and the directional intra prediction modes.

[00394] In the example shown in FIG. 34, directional prediction modes may range from diagonal down and left direction to diagonal up and right direction. Where the following description assumes the angle formed between the x-axis and the directional prediction mode, directional prediction modes can range from 45 degrees (diagonally down and left) to -135 degrees (diagonally up and right).

[00395] When the current block has a non-square shape, a prediction sample may be obtained using a reference sample far from the prediction sample from reference samples located on the corner line corresponding to the intra prediction angle, instead of a reference sample near the prediction sample depending on the intra prediction mode of the current block.

[00396] In FIG. 35 is a schematic view showing an aspect in which a prediction count is obtained when the current block has a non-square shape.

[00397] For example, as in the example shown in FIG. 35A, it is assumed that the current block has a non-square shape in which the width is greater than the height, and that the intra prediction mode of the current block is a directional intra prediction mode having an angle from 0 degrees to 45 degrees. In this case, when obtaining the prediction sample A near the right column of the current block, the left reference sample L away from the prediction sample may be used instead of the top reference sample T near the prediction sample from the reference samples located on the corner line corresponding to the corner.

[00398] As another example, as in the example shown in FIG. 35B, it is assumed that the current block has a non-square shape in which the height is greater than the width, and that the intra prediction mode of the current block is a directional intra prediction mode having an angle of -90 degrees to -135 degrees. In this case, when obtaining a prediction sample A near the bottom line of the current block, the top reference sample T away from the prediction sample from the reference samples located on the corner line corresponding to the corner may be used instead of the left reference sample L near the prediction sample.

[00399] To solve this problem, when the current block has a non-square shape, the intra prediction mode of the current block can be replaced by an intra prediction mode in the opposite direction. Thus, for non-square shaped blocks, directional prediction modes having an angle that is larger or smaller than those of the directional prediction modes shown in FIG. 31. Such a directional intra prediction mode may be set as a wide-angle intra prediction mode. The wide-angle intra prediction mode represents the directional intra prediction mode, which is not in the range of 45 degrees to -135 degrees.

[00400] In FIG. 36 is a schematic diagram showing wide-angle intra prediction modes.

[00401] In the example shown in FIG. 36, wide-angle intra prediction modes are indicated by intra prediction modes indexed from -1 to -14 and intra prediction modes indexed from 67 to 80.

[00402] In FIG. 36 illustrates 14 wide-angle intra prediction modes having an angle that is greater than 45 degrees (-1 to -14), and 14 wide-angle intra prediction modes having an angle that is less than -135 degrees (67 to 80), but can be specified more or less wide-angle intra prediction modes.

[00403] When the wide-angle intra prediction mode is used, the length of the top reference samples can be set to 2W+1, and the length of the left reference samples can be set to 2H+1.

[00404] When the wide-angle intra prediction mode is used, count A shown in FIG. 35A can be predicted using the reference sample T, and the sample A shown in FIG. 35B can be predicted using the reference sample L.

[00405] By adding N wide-angle intra prediction modes to the existing intra prediction modes, a total of 67+N intra prediction modes can be used. As an example, Table 6 shows the inner direction parameters of the intra prediction modes when 20 wide-angle intra prediction modes are specified.

[00406] [Table 6]

[00407] The internal direction parameters may be set differently based on at least one of the size, shape, or reference line of the current block. As an example, the intra direction parameter for a particular intra prediction mode when the current block is square may be different from when the current block is non-square. As an example, the internal direction parameter intraPredAngle of intra prediction mode #15 may have a greater value when the current block is square than when the current block is non-square.

[00408] Alternatively, the internal direction parameter intraPredAngle of intra prediction mode No. 75 may have a larger value when the reference sample line index of the current block is 1 or more than when the reference sample line index of the current block is 0.

[00409] When the current block has a non-square shape, and the intra prediction mode of the current block obtained in step S2902 is within the conversion range, the intra prediction mode of the current block can be converted to a wide-angle intra prediction mode. The transformation range may be determined based on at least one of the size, shape, or ratio of the current block. In this case, the ratio can indicate the relationship between the width and height of the current block.

[00410] When the current block has a non-square shape in which the width is greater than the height, the transformation range can be set to a range from the intra prediction mode index in the diagonal up and right direction (for example, 66) to the intra prediction mode index in the diagonal up and right direction minus N. In this case, N can be determined based on the ratio of the current block. When the intra prediction mode of the current block is within the conversion range, the intra prediction mode can be converted to a wide-angle intra prediction mode. The conversion may be the subtraction of a predetermined value from the intra prediction mode, and the predetermined value may be the total number (eg, 67) of intra prediction modes excluding wide-angle intra prediction modes.

[00411] According to the above-described embodiment, intra prediction modes No. 66 to No. 53 can be converted to wide-angle intra prediction modes No.-1 to No.-14, respectively.

[00412] When the current block has a non-square shape in which the height is greater than the width, the transformation range can be set to a diagonal down-left intra prediction mode index (eg, 2) to a down-left intra prediction mode index plus M. In this case, M can be determined based on the ratio of the current block. When the intra prediction mode of the current block is within the conversion range, the intra prediction mode can be converted to a wide-angle intra prediction mode. The transformation may be adding a predetermined value to the intra prediction mode, and the predetermined value may be the total number (eg, 65) of directional intra prediction modes excluding wide-angle intra prediction modes.

[00413] According to the above-described embodiment, intra prediction modes No. 2 to No. 15 can be converted to wide-angle intra prediction modes No. 67 to No. 80, respectively.

[00414] Intra prediction modes that are within the transform range will be referred to as alternative wide-angle intra prediction modes.

[00415] The conversion range can be determined based on the ratio of the current block. As an example, Table 7 and Table 8 show the conversion range when 35 intra prediction modes excluding wide-angle intra prediction modes are specified, and the prediction range when 67 intra prediction modes are specified.

[00416] [Table 7]

[00417] [Table 8]

[00418] In the examples shown in Table 7 and Table 8, the number of alternative wide-angle intra prediction modes within the conversion range may differ depending on the ratio of the current block.

[00419] Since wide-angle intra prediction modes are used in addition to existing intra prediction modes, resources required to encode wide-angle intra prediction modes may increase, and thus coding efficiency may decrease. Accordingly, coding efficiency can be improved by encoding alternative intra prediction modes for wide-angle intra prediction modes instead of encoding wide-angle intra prediction modes as is.

[00420] As an example, when the current block is encoded in the wide-angle intra prediction mode #67, the wide-angle intra prediction mode #2, which is an alternative wide-angle intra prediction mode for #67, may be encoded into the intra prediction mode of the current block. In addition, when the current block is encoded in the wide-angle intra prediction mode No.-1, the wide-angle intra prediction mode No. 66, which is an alternative wide-angle intra prediction mode for No.-1, can be encoded into the intra prediction mode of the current block.

[00421] The decoder may decode the intra prediction mode of the current block and may determine whether the decoded intra prediction mode is within the transform range. When the decoded intra prediction mode is an alternative wide-angle intra prediction mode, the intra prediction mode can be converted to a wide-angle intra prediction mode.

[00422] Alternatively, when the current block is encoded in the wide-angle intra prediction mode, the wide-angle intra prediction mode may be encoded as is.

[00423] Intra prediction mode coding may be performed based on the above-described MPM list. In detail, when a neighboring block is encoded in the wide-angle intra prediction mode, the MPM can be set based on the alternative wide-angle intra prediction mode corresponding to the wide-angle intra prediction mode. As an example, when a neighboring block is encoded in the wide-angle intra prediction mode, the variable candIntraPredX (X represents A or B) may be set as the alternative wide-angle intra prediction mode.

[00424] When a prediction block is generated as a result of performing intra prediction, the prediction samples may be updated based on the locations of the prediction samples included in the prediction block. The updating method may be called a position-based intra-weighted prediction method (or position-dependent prediction combination (PDPC)).

[00425] Whether to use PDPC may be determined taking into account the intra prediction mode of the current block, the reference sample line of the current block, the size of the current block, or the color component. As an example, PDPC may be used when the intra prediction mode of the current block is at least one of a mode having a lower index value than a planar mode, a DC mode, a vertical mode and a horizontal mode, or a mode having a higher index value than horizontal mode. Alternatively, PDPC may only be used when at least one of the current block's width and height is greater than 4. Alternatively, PDPC may only be used when the reference picture line index of the current block is 0. Alternatively, PDPC may only be used when the reference picture line index current block is greater than or equal to a preset value. Alternatively, PDPC can be used for the luminance component only. Alternatively, whether to use PDPC can be determined according to whether two or more of the above conditions are satisfied.

[00426] As another example, information indicating whether to apply PDPC may be transmitted in a bitstream.

[00427] When a prediction sample is obtained using an intra prediction sample, a reference sample used to correct the prediction sample can be determined based on the location of the acquired prediction sample. For convenience of description, in the following embodiments, the reference sample used to correct the prediction sample will be referred to as a PDPC reference sample. In addition, the prediction sample obtained by intra prediction will be called the first prediction sample, and the prediction sample obtained by correcting the first prediction sample will be called the second prediction sample.

[00428] In FIG. 37 is a schematic diagram showing an application aspect of PDPC.

[00429] The first prediction sample may be adjusted using at least one PDPC reference sample. The PDPC reference sample may include at least one of a reference sample adjacent to an upper left corner of the current block, an upper reference sample located above the current block, and a left reference sample located to the left of the current block.

[00430] At least one of the reference samples belonging to the reference sample line of the current block may be set as the PDPC reference sample. Alternatively, regardless of the reference sample line of the current block, at least one reference sample belonging to the reference sample line with index 0 may be set as the PDPC reference sample. As an example, although the first prediction sample is obtained using the reference samples included in the line reference samples with index 1 or index 2, a second prediction sample can be obtained using the reference samples included in the line of reference samples with index 0.

[00431] The number or locations of PDPC reference samples used to correct the first prediction sample may be determined taking into account at least one of the intra prediction modes of the current block, the size of the current block, the shape of the current block, or the location of the first prediction sample.

[00432] As an example, when the intra prediction mode of the current block is planar mode or DC mode, the second prediction sample may be obtained using the top reference sample and the left reference sample. In this case, the top reference sample may be a reference sample perpendicular to the first prediction sample (for example, a reference sample having the same x-coordinate), and the left reference sample may be a reference sample parallel to the first prediction sample (for example, a reference sample having the same y coordinate).

[00433] When the intra prediction mode of the current block is the horizontal intra prediction mode, the second prediction sample may be obtained using the upper reference sample. In this case, the upper reference sample may be a reference sample perpendicular to the first prediction sample.

[00434] When the intra prediction mode of the current block is the vertical intra prediction mode, the second prediction sample may be obtained using the left reference sample. In this case, the left reference sample may be a reference sample parallel to the first prediction sample.

[00435] When the intra prediction mode of the current block is a diagonal intra prediction mode in the down and left direction or a diagonal intra prediction mode in the up and right direction, the second prediction sample can be obtained based on the upper left reference sample, the upper reference sample and the left reference sample . The top left reference sample may be a reference sample adjacent to the top left corner of the current block (eg, a reference sample located at (-1, -1)). The top reference sample may be a reference sample located diagonally above and to the right of the first prediction sample, and the left reference sample may be a reference sample located diagonally below and to the left of the first prediction sample.

[00436] To summarize, when the location of the first prediction sample is (x, y), the top left reference sample can be set to R(-1, -1), and the top reference sample can be set to R(x+y +1, -1) or R(x, -1). In addition, R(-1, x+y+1) or R(-1, y) can be set as the left reference count.

[00437] As another example, the location of the left reference count or the top reference count may be determined taking into account at least one of the shape of the current block or whether a wide-angle internal mode has been applied.

[00438] In detail, when the intra prediction mode of the current block is the wide-angle intra prediction mode, the reference sample located at an offset distance from the reference sample located diagonally with respect to the first prediction sample can be set as the PDPC reference sample. As an example, the top reference sample R(x+y+k+1, -1) and the left reference sample R(-1, x+y-k+1) may be set as the PDPC reference samples.

[00439] In this case, the offset k can be determined based on the wide-angle intra prediction mode. Equation 6 and Equation 7 present an example of obtaining the offset based on the wide-angle intra prediction mode.

[00440] [Equation 6]

[00441] [Equation 7]

[00442] The second prediction sample may be determined based on a weighted sum operation of the first prediction sample and the PDPC reference samples. As an example, the second prediction sample can be obtained based on Equation 8 below.

[00443] [Equation 8]

[00444] In Equation 8, RL represents the left reference sample, RT represents the top reference sample, and RTL represents the top left reference sample. pred(x,y) represents the prediction sample located at (x,y). wL represents a weight assigned to the left reference sample, wT represents a weight assigned to the top reference sample, and wTL represents a weight assigned to the top left reference sample. The weight assigned to the first prediction sample can be obtained by subtracting the weights assigned to the reference samples from the maximum value. For ease of description, the weight assigned to the PDPC reference sample will be referred to as the PDPC weight.

[00445] The weight assigned to each reference sample may be determined based on at least one of the intra prediction mode of the current block or the location of the first prediction sample.

[00446] As an example, at least one of wL, wT, or wTL may be directly or inversely proportional to at least one of the x coordinate or y coordinate of the prediction sample. Alternatively, at least one of wL, wT, or wTL may be directly or inversely proportional to at least one of the width or height of the current block.

[00447] When the intra prediction mode of the current block is DC mode, the PDPC weights can be determined from Equation 9 below.

[00448] [Equation 9]

[00449] In Equation 9, x and y represent the location of the first prediction sample.

[00450] In Equation 9, the shift variable used for the bit shift operation can be obtained based on the width or height of the current block. As an example, the shift variable can be derived from Equation 10 or 11 below.

[00451] [Equation 10]

[00452] [Equation 11]

[00453] Alternatively, the shift variable can be derived from the current block's internal direction parameter.

[00454] The number or types of parameters used to obtain the shift variable may be determined differently depending on the intra prediction mode of the current block. As an example, when the intra prediction mode of the current block is planar mode, DC mode, vertical mode or horizontal mode, the shift variable can be obtained using the width and height of the current block, as in the example shown in Equation 10 or Equation 11. When the intra prediction mode of the current block is an intra prediction mode having an index that is greater than that of the vertical intra prediction mode, the shift variable can be obtained using the intra direction and height parameter of the current block. When the intra prediction mode of the current block is an intra prediction mode having an index that is smaller than that of the horizontal intra prediction mode, the shift variable can be obtained using the intra direction and width parameter of the current block.

[00455] When the intra prediction mode of the current block is planar mode, the value of wTL can be set to 0. wL and wT can be obtained based on Equation 12 below.

[00456] [Equation 12]

[00457] When the intra prediction mode of the current block is the horizontal intra prediction mode, wT may be set to 0, and wTL and wL may be set identically. On the other hand, when the intra prediction mode of the current block is the vertical intra prediction mode, wL can be set to 0, and wTL and wL can be set identically.

[00458] When the intra prediction mode of the current block is an up-right intra prediction mode having an index value that is greater than that of the vertical intra prediction mode, the PDPC weights can be obtained using Equation 13 below.

[00459] [Equation 13]

[00460] On the other hand, when the intra prediction mode of the current block is a down-left intra prediction mode having an index value that is smaller than that of the horizontal intra prediction mode, the PDPC weights can be obtained using Equation 14 below.

[00461] [Equation 14]

[00462] As in the above-described embodiments, the PDPC weights can be determined based on the x and y positions of the prediction sample.

[00463] As another example, a weight assigned to each PDPC reference sample may be defined in subblock elements. The prediction samples included in a sub-block may share the same PDPC weights.

[00464] The size of the subblock, which is the basis for determining the weights, can be preset in the encoder and decoder. As an example, weights may be determined for 2x2 or 4x4 subblocks.

[00465] Alternatively, the size, shape, or number of subblocks may be determined depending on the size or shape of the current block. As an example, a coding block may be divided into four sub-blocks regardless of the size of the coding block. Alternatively, depending on the size of the coding block, the coding block can be divided into four or sixteen sub-blocks.

[00466] Alternatively, the size, shape, or number of subblocks may be determined depending on the intra prediction mode of the current block. As an example, when the intra prediction mode of the current block is horizontal mode, N columns (or N rows) may be set as one sub-block, and when the intra prediction mode of the current block is vertical mode, N rows (or N rows) may be set as one sub-block. or N columns).

[00467] Equations 15-17 provide an example of determining the PDPC weights for a 2x2 subblock. Equation 15 illustrates that the intra prediction mode of the current block is DC mode.

[00468] [Equation 15]

[00469] In Equation 15, K may be a value determined based on the intra prediction mode or subblock size.

[00470] In Equation 16, it is illustrated that the intra prediction mode of the current block is an up-right intra prediction mode having an index value that is greater than that of the vertical intra prediction mode.

[00471] [Equation 16]

[00472] In Equation 17, it is illustrated that the intra prediction mode of the current block is a down-left intra prediction mode having an index value that is less than that of the horizontal intra prediction mode.

[00473] [Equation 17]

[00474] In equations 15-17, x and y represent the location of the reference sample in the subblock. The reference sample may be one of a sample located in the upper left corner of the subblock, a sample located in the center of the subblock, or a sample located in the lower right corner of the subblock.

[00475] Equations 18-20 provide an example of determining the PDPC weights for a 4x4 subblock. Equation 18 illustrates that the intra prediction mode of the current block is DC mode.

[00476] [Equation 18]

[00477] In Equation 19, it is illustrated that the intra prediction mode of the current block is an up-right intra prediction mode having an index value that is greater than that of the vertical intra prediction mode.

[00478] [Equation 19]

[00479] In Equation 20, it is illustrated that the intra prediction mode of the current block is a down-left intra prediction mode having an index value that is less than that of the horizontal intra prediction mode.

[00480] [Equation 20]

[00481] In the above embodiments, the PDPC weights are described as being determined taking into account the locations of the prediction samples included in the subblock or the first prediction sample. PDPC weights can be further determined based on the current block.

[00482] As an example, in the case of DC mode, the method of obtaining the PDPC weights may vary depending on whether the current block has a non-square shape in which the width is greater than the height, or a non-square shape in which the height is greater than the width.

[00483] Equation 21 shows an example of obtaining PDPC weights when the current block has a non-square shape in which the width is greater than the height, and Equation 22 shows an example of obtaining the PDPC weights when the current block has a non-square shape in which the height is greater than the width.

[00484] [Equation 21]

[00485] [Equation 22]

[00486] When the current block has a non-square shape, the current block can be predicted using the wide-angle intra prediction mode. Even when wide-angle intra prediction is applied, the first prediction sample can be updated by applying PDPC.

[00487] When wide-angle intra prediction is applied to the current block, PDPC weights can be determined taking into account the shape of the coding block.

[00488] As an example, when the current block has a non-square shape in which the width is greater than the height, the top reference sample located to the right and above the first prediction sample may be closer to the first prediction sample than the left reference sample located to the left and below the first prediction sample, depending on the location of the first prediction sample. Accordingly, when the first prediction sample is corrected, the weight applied to the upper reference sample can be set to be larger than the weight applied to the left reference sample.

[00489] On the other hand, when the current block has a non-square shape in which the height is greater than the width, the left reference sample located to the left and below the first prediction sample may be closer to the first prediction sample than the top reference sample located to the right and above the first prediction sample, depending on the location of the first prediction sample. Accordingly, when the first prediction sample is subject to correction, the weight applied to the left reference sample can be set to be larger than the weight applied to the upper reference sample.

[00490] Equation 23 provides an example of obtaining PDPC weights when the intra prediction mode of the current block is a wide-angle intra prediction mode with an index that is greater than 66.

[00491] [Equation 23]

[00492] Equation 24 provides an example of obtaining PDPC weights when the intra prediction mode of the current block is a wide-angle intra prediction mode with an index that is less than 0.

[00493] [Equation 24]

[00494] PDPC weights may be determined based on the ratio of the current block. The current block ratio indicates the width and height ratio of the current block, and it can be set using Equation 25 below.

[00495] [Equation 25]

[00496] The method for obtaining the PDPC weights may be determined in a variable manner depending on the intra prediction mode of the current block.

[00497] As an example, Equation 26 and Equation 27 present an example of obtaining PDPC weights when the intra prediction mode of the current block is DC mode. In detail, Equation 26 is an example in which the current block has a non-square shape in which the width is greater than the height, and Equation 27 is an example in which the current block has a non-square shape in which the height is greater than the width.

[00498] [Equation 26]

[00499] [Equation 27]

[00500] Equation 28 provides an example of obtaining PDPC weights when the intra prediction mode of the current block is a wide-angle intra prediction mode with an index that is greater than 66.

[00501] [Equation 28]

[00502] Equation 29 provides an example of obtaining PDPC weights when the intra prediction mode of the current block is a wide-angle intra prediction mode with an index that is less than 0.

[00503] [Equation 29]

[00504] The residual block can be obtained by subtracting the prediction from the original block. In this case, when the residual block is changed to the frequency domain, the subjective quality of the video is not significantly reduced even if the high frequency components are removed from the frequency components. Accordingly, when the values of the high-frequency components are changed to small values, or when the values of the high-frequency components are set to 0, it is possible to improve the compression efficiency without causing significant visual distortion. Considering the characteristics described above, the current block can be transformed to decompose the residual block into two-dimensional frequency components. The conversion can be performed using a conversion method such as discrete cosine transform (DCT) or discrete sine transform (DST).

[00505] In DCT, a cosine transform is used to decompose (or transform) a residual block into (in) two-dimensional frequency components, and in DST, a sine transform is used to decompose (or transform) a residual block into (in) two-dimensional frequency components. As a result of the residual block transformation, the frequency components can be expressed using the basic circuit. As an example, when DCT is performed on an N×N block, N2 base circuit components can be obtained. The size of each of the base circuit components included in the N×N block can be obtained using a transformation. According to the conversion method used, the component size of the underlying circuit may be called the DCT coefficient or the DST coefficient.

[00506] The DCT transform method is mainly used to transform a block in which a plurality of non-zero low-frequency components are distributed. The DST conversion method is mainly used for a block in which many high-frequency components are distributed.

[00507] The residual block may be transformed using a transformation method other than DCT or DST.

[00508] The transformation of the residual block into two-dimensional frequency components will be called a two-dimensional transformation. In addition, the size of the base circuit components obtained by the transformation result will be called the transformation factor. As an example, the conversion coefficient may be called the DCT coefficient or the DST coefficient. When both of the first transform and the second transform, which will be described below, are applied, the transform factor may relate to the size of the base circuit component generated as a result of the second transform.

[00509] The conversion method may be defined in block elements. The transformation method may be determined based on at least one of a prediction mode of the current block or a size of the current block. As an example, when the current block is encoded in the intra prediction mode, and the size of the current block is less than N×N, the transformation may be performed using the DST transformation method. On the other hand, when the above condition is not satisfied, the conversion can be performed using the DCT conversion method.

[00510] The two-dimensional transformation may not be performed on some of the residual blocks. Failure to perform a two-dimensional transformation may be called a skip transformation. When skip conversion is applied, quantization can be applied to the residual values on which no conversion is performed.

[00511] After transforming the current block using DCT or DST, the transformed current block may be re-transformed. In this case, a transformation based on DCT or DST may be specified as the first transformation, and a retransformation of the block subject to the first transformation may be specified as the second transformation.

[00512] The first transformation may be performed using one of a plurality of candidate transformation bases. As an example, the first conversion may be performed using one of DCT2, DCT8 and DCT7.

[00513] Different transformation bases may be used in the horizontal direction and the vertical direction. Information indicating the combination of a vertical transform base and a horizontal transform base may be transmitted in the bit stream.

[00514] The first transformation and the second transformation may be performed in different elements. As an example, the first transformation may be performed on an 8×8 block, and the second transformation may be performed on a 4×4 subblock of the transformed 8×8 block. In this case, the transformation factor of the residual regions in which the second transformation is not performed can be set to 0.

[00515] Alternatively, the first transform may be performed on the 4x4 block and the second transform may be performed on the region of the 8x8 block containing the transformed 4x4 block.

[00516] Information indicating whether to perform the second conversion may be transmitted in the bitstream.

[00517] Alternatively, whether to perform the second transformation may be determined based on whether the horizontal transformation basis and the vertical transformation basis are identical. As an example, the second transformation can be performed only when the horizontal transformation basis and the vertical transformation basis are identical. Alternatively, the second transformation may be performed only when the horizontal transformation basis and the vertical transformation basis are different.

[00518] Alternatively, the second transform may only be valid when the horizontal transform and vertical transform use a predefined transform basis. As an example, the second transform may be valid when the DCT2 transform basis is used for the horizontal transform and vertical transform.

[00519] Alternatively, whether to perform the second transform may be determined based on the number of non-zero transform coefficients of the current block. As an example, it may be set to not use the second transform when the non-zero transform gain of the current block is less than or equal to a threshold value, and it may be set to use the second transform when the non-zero transform gain of the current block is greater than the threshold value. It can be set to use the second transform only when the current block is encoded using intra prediction.

[00520] The size or shape of the subblock to be subjected to the second transformation may be determined based on the shape of the current block.

[00521] In FIG. 38 and 39 are schematic diagrams showing a subblock to be subjected to the second transformation.

[00522] When the current block is square, a second transformation may be performed on an N×N subblock located in the upper left corner of the current block after the first transformation is performed. As an example, when the current block is an 8×8 encoding block, a second transform may be performed on a 4×4 sub-block located in the upper left corner of the current block after performing the first transform on the current block (see FIG. 38).

[00523] When the current block has a non-square shape in which the width is four or more times the height, the second transformation may be performed on the kN×4kN subblock located in the upper left corner of the current block after performing the first transformation. As an example, when the current block is non-square with a size of 16x4, a first transformation may be performed on the current block, and then a second transformation may be performed on a 2x8 subblock located in the upper left corner of the current block (see FIG. 39A).

[00524] When the current block has a non-square shape in which the height is four or more times the width, a second transformation may be performed on a 4kN×kN subblock located in the upper left corner of the current block after the first transformation is performed. As an example, when the current block is non-square with a size of 16x4, a first transformation may be performed on the current block, and then a second transformation may be performed on a 2x8 subblock located in the upper left corner of the current block (see FIG. 39B).

[00525] The decoder may inverse the second transform (second inverse transform) and may inverse the first transform (first inverse transform) with respect to the result of the second inverse transform. By performing the second deconversion and the first deconversion, residual signals for the current block can be obtained.

[00526] Quantization is performed to reduce the block energy, and the quantization process involves dividing the conversion coefficient by a specific constant value. This constant value can be obtained by a quantization parameter, and the quantization parameter can be specified as a value from 1 to 63.

[00527] When the encoder performs the transform and quantization, the decoder can obtain the residual block by inverse quantization and inverse transform. The decoder can obtain a reconstructed block for the current block by adding the prediction block and the residual block.

[00528] Information indicating the prediction type of the current block may be transmitted in a bit stream. The information may be index information tu_mts_idx indicating one of a plurality of combinations of a horizontal transformation type and a vertical transformation type.

[00529] The vertical transformation basis and the horizontal transformation basis may be determined based on the transformation candidate types indicated by the index information tu_mts_idx. Table 9 and Table 10 show combinations of conversion types corresponding to tu_mts_idx.

[00530] [Table 9]

[00531] [Table 10]

[00532] The conversion type may be determined to be one of DCT2, DST7, DCT8, or skip conversion. Alternatively, candidate transformation type combinations can be constructed using only the transformation stems excluding the skip transformation.

[00533] When using table 9, when tu_mts_idx is 0, skip conversion may be applied in the horizontal direction and vertical direction. When tu_mts_idx is 1, DCT2 can be applied in the horizontal direction and vertical direction. When tu_mts_idx is 3, DCT8 can be applied in the horizontal direction, and DCT7 can be applied in the vertical direction.

[00534] When using table 10, when tu_mts_idx is 0, DCT2 can be applied in the horizontal direction and vertical direction. When tu_mts_idx is 1, skip conversion can be applied in the horizontal direction and vertical direction. When tu_mts_idx is 3, DCT8 can be applied in the horizontal direction, and DCT7 can be applied in the vertical direction.

[00535] Whether to encode index information may be determined based on at least one of the size or shape of the current block or the number of non-zero coefficients. As an example, when the number of non-zero coefficients is less than or equal to a threshold, index information may not be transmitted and a default transform type may be applied to the current block. In this case, the default conversion type may be DST7. Alternatively, the default mode may vary depending on the size, shape, or intra prediction mode of the current block.

[00536] The threshold value may be determined based on the size or shape of the current block. As an example, the threshold value may be set to 2 when the current block size is less than or equal to 32×32, and the threshold value may be set to 4 when the current block size is greater than 32×32 (for example, when the current block is encoding block 32 ×64 or 64×32).

[00537] A plurality of lookup tables may be previously stored in the encoder or decoder. At least one of the index values assigned to the transformation type candidate combinations, the transformation type candidate combination types, or the number of transformation type candidate combinations may be different for each of the plurality of lookup tables.

[00538] The lookup table of the current block may be selected based on at least one of the size, shape, prediction mode, or intra prediction mode of the current block, whether to apply a secondary transform, or whether to apply a skip transform to an adjacent block.

[00539] As an example, the lookup table presented in Table 9 may be used when the size of the current block is less than or equal to 4×4, or when the current block is encoded using inter-picture prediction and the lookup table presented in the table 10 may be used when the size of the current block is greater than 4x4, or when the current block is encoded using intra prediction.

[00540] Alternatively, information indicating one of a plurality of lookup tables may be transmitted in a bit stream. Based on the information, the decoder can select a lookup table for the current block.

[00541] As another example, an index assigned to a candidate transform type combination may be determined adaptively based on at least one of the size, shape, prediction mode, or intra prediction mode of the current block, whether to apply a secondary transform, or whether whether to apply skip transformation to an adjacent block. As an example, the index assigned to the conversion skip when the current block size is 4×4 may have a smaller value than the index assigned to the conversion skip when the current block size is greater than 4×4. In detail, index 0 can be assigned to a conversion skip when the current block size is 4x4, and an index that is greater than 0 (for example, index 1) can be assigned to a conversion skip when the current block size is greater than 4x4 and less than or equal to 16 ×16. When the current block size is greater than 16x16, the transform skip index can be set to the maximum value (eg, 5).

[00542] Alternatively, when the current block is encoded using inter-picture prediction, the transform skip may be assigned an index of 0. When the current block is encoded using intra-prediction, the transform skip may be assigned an index that is greater than 0 (e.g., index 1 ).

[00543] Alternatively, when the current block is a 4x4 block encoded by inter-picture prediction, the transform skip may be assigned an index of 0. On the other hand, when the current block is not encoded by inter-picture prediction, or when the current block is larger than 4x4, the conversion skip may be assigned an index that is greater than 0 (for example, index 1).

[00544] Candidate transform type combinations other than the candidate transform type combinations listed in Table 9 and Table 10 may be defined and used. As an example, skip transform may be applied to one of the horizontal transform or the vertical transform, and for the other of these, a combination of candidate transformation types may be used to which a transformation basis such as DCT7, DCT8 or DST2 is applied. In this case, whether to use transformation skip for a horizontal transformation candidate type or a vertical transformation candidate type may be determined based on at least one of size (e.g., width and/or height), shape, prediction mode, or internal mode predictions of the current block.

[00545] Alternatively, information indicating whether a particular conversion candidate type is available may be carried in the bit stream. As an example, a flag may be transmitted indicating whether to use skip conversion for the horizontal direction and vertical direction as the conversion candidate type. According to the flag, it can be determined whether a particular conversion type candidate combination is included from a plurality of conversion type candidate combinations.

[00546] Alternatively, whether a particular conversion candidate type applies to the current block may be conveyed in the bit stream. As an example, a cu_mts_flag may be transmitted indicating whether to apply DCT2 in the horizontal direction and vertical direction. When the value of cu_mts_flag is 1, the conversion basis for the vertical direction and horizontal direction can be set to DCT2. When the value of cu_mts_flag is 0, the conversion basis for vertical direction and horizontal direction can be set to DCT8 or DST7. Alternatively, when the value of cu_mts_flag is 0, tu_mts_idx information may be transmitted indicating one of a plurality of candidate transformation type combinations.

[00547] When the current block has a non-square shape in which the width is greater than the height, or a non-square shape in which the height is greater than the width, the cu_mts_flag encoding may be skipped and the value of cu_mts_flag may be considered zero.

[00548] The number of available transform type candidate combinations may be set differently depending on the size, shape, or intra prediction mode of the current block. As an example, when the current block is square, three or more candidate transformation type combinations may be used, and when the current block is non-square, two candidate transformation type combinations may be used. Alternatively, when the current block is square, only candidate transformation type combinations that have a horizontal transformation type and a vertical transformation type different from each other from the candidate transformation type combinations can be used.

[00549] When three or more candidate transformation type combinations may be used for the current block, index information tu_mts_idx indicating one of the candidate transformation type combinations may be transmitted. On the other hand, when two candidate transformation type combinations may be used for the current block, an mts_flag may be transmitted indicating one of the candidate transformation type combinations. Table 11 below presents the information encoding aspect for indicating candidate combinations of transformation types according to the shape of the current block.

[00550] [Table 11]

[00551] The indices of candidate transformation type combinations may be permuted (or reordered) according to the shape of the current block. As an example, the indices assigned to candidate transformation type combinations when the current block is square may be different from the indices assigned to candidate transformation type combinations when the current block is non-square. As an example, when the current block is square, a combination of transformation types can be selected based on Table 12, and when the current block is non-square, a combination of transformation types can be selected based on Table 13.

[00552] [Table 12]

[00553] [Table 13]

[00554] The transformation type may be determined based on the number of horizontal non-zero coefficients of the current block or the number of vertical non-zero coefficients of the current block. In this case, the number of horizontal non-zero coefficients indicates the number of non-zero coefficients included in 1×N (where N represents the width of the current block), and the number of vertical non-zero coefficients indicates the number of non-zero coefficients included in N×1 (where N represents the height of the current block ). When the maximum value of the horizontal non-zero coefficients is less than or equal to the threshold value, the first type of transformation may be applied in the horizontal direction, and when the maximum value of the horizontal non-zero coefficients is greater than the threshold value, the second type of transformation may be applied in the horizontal direction. When the maximum value of the vertical non-zero coefficients is less than or equal to the threshold value, the first type of transformation may be applied in the vertical direction, and when the maximum value of the vertical non-zero coefficients is greater than the threshold value, the second type of transformation may be applied in the vertical direction.

[00555] In FIG. 40 is a schematic diagram for describing an example in which the transformation type of the current block is determined.

[00556] As an example, when the current block is encoded using intra prediction, and the maximum value of the horizontal non-zero coefficients of the current block is less than or equal to 2 (see FIG. 40A), DST7 may be specified as the horizontal transform type.

[00557] When the current block is encoded using intra prediction, and the maximum value of the vertical non-zero coefficients of the current block is greater than 2 (see FIG. 40B), DCT2 or DCT8 may be specified as the vertical transform type.

[00558] The residual coefficient may be encoded in transform elements or in subtransform elements. Here, the residual coefficient refers to a transform coefficient generated by transforming, a transform skipping coefficient generated by skipping transforming, or a quantized coefficient generated by quantizing a transform coefficient or coefficient.

[00559] A transform element may refer to a block that is subject to a first transform or a second transform. A subtransform element refers to a block with a smaller size than that of the transform element. As an example, the subtransform element may be a 4x4, 2x8, or 8x2 block.

[00560] At least one of the size or shape of the subtransform element may be determined based on the size or shape of the current block. As an example, the subtransform element is also set to have a non-square shape in which the width is greater than the height (for example, 8×2), when the current block has a non-square shape in which the width is greater than the height, and the subtransform element may also be set to have a non-square shape , in which the height is greater than the width (for example, 2x8), when the current block has a non-square shape, in which the height is greater than the width. When the current block is square, the subtransform element can also be set to have a square shape (eg, 4x4).

[00561] When multiple sub-transform elements are included in the current block, the sub-transform elements may be encoded or decoded sequentially. The residual coefficient may be encoded using entropy encoding such as arithmetic encoding. The method for encoding or decoding the residual coefficient will be described in detail below with reference to graphic materials.

[00562] In FIG. 41 is a flowchart showing a residual coefficient encoding method.

[00563] In this embodiment, it is assumed that the current block contains one or more subtransform elements. In addition, the subtransform element is assumed to be of size 4x4. However, this embodiment can be applied as such even when the size of the sub-transform element or the shape of the sub-transform element is different from that described above.

[00564] It can be determined (S4101) whether a non-zero coefficient is present in the current block. A non-zero coefficient indicates a residual coefficient whose absolute value is greater than 0. Information indicating whether a non-zero coefficient is present in the current block may be encoded and transmitted. As an example, the information may be a 1-bit flag and may be a coded block flag (CBF).

[00565] When a non-zero coefficient is present in the current block, it can be determined (S4102) whether a non-zero coefficient is present for each sub-transform element. Information indicating whether a non-zero coefficient is present for each subtransform element may be encoded and transmitted. As an example, the information may be a 1-bit flag and may be a coded subblock flag (CSBF). The subtransform elements can be encoded in a preselected scan order.

[00566] When a non-zero coefficient is present in the sub-transform element, to encode (S4103) the residual coefficients of the sub-transform element, the residual coefficients in the sub-transform element can be arranged in one dimension. The residual coefficients can be arranged in one dimension in a preselected scan order.

[00567] The scanning order may include at least one of diagonal scanning, horizontal scanning, vertical scanning, or their inverse scanning orders.

[00568] In FIG. 42 and 43 are schematic diagrams showing the arrangement of residual coefficients for each scanning order.

[00569] In FIG. 42A-42C show diagonal scanning, horizontal scanning and vertical scanning, and FIG. 43A-43C show their reverse scan orders.

[00570] The residual coefficients can be arranged in one dimension in the selected scanning order.

[00571] The scan order may be determined based on at least one of the size, shape, or intra prediction mode of the current block, the transform basis used for the primary transform, or whether to apply a secondary transform. As an example, when the current block has a non-square shape in which the width is greater than the height, the residual coefficient may be encoded using an inverse horizontal scan. On the other hand, when the current block has a non-square shape in which the height is greater than the width, the residual coefficient can be encoded using an inverse vertical scan.

[00572] Alternatively, a rate-distortion optimization (RDO) may be calculated for each of the plurality of scan orders, and the scan order having the minimum RDO may be determined as the scan order of the current block. In this case, information indicating the scanning order of the current block can be encoded and transmitted.

[00573] The candidate scan order that can be used when encoding the transform skip coefficient may be different from the candidate scan order that can be used when encoding the transform coefficient. As an example, an order inverse to a scan candidate order that can be used when encoding a transform coefficient can be set as a scan candidate order that can be used to encode a transform skip coefficient.

[00574] As an example, when the transform coefficient is encoded using one of an inverse diagonal scan, an inverse horizontal scan, or an inverse vertical scan, the transform skip coefficient may be encoded using one of a diagonal scan, a horizontal scan, or a vertical scan.

[00575] The location of the last scanned non-zero coefficient in the transform block may then be encoded (S4103). The x-axis location and y-axis location of the last non-zero coefficient may be encoded.

[00576] In FIG. 44 shows an example in which the location of the last non-zero coefficient is encoded.

[00577] In the example shown in FIG. 44, when applying diagonal scanning, the residual coefficient located in the upper right corner of the transform block can be set as the last non-zero coefficient. The x-coordinate, LastX, of the residual coefficient is 3, and the y-coordinate, LastY, of the residual coefficient is 0. LastX can be encoded by being divided into last_sig_coeff_x_prefix, which is a prefix part, and last_sig_coeff_x_suffix, which is a suffix part. LastY may also be encoded being split into last_sig_coeff_y_prefix, which is the prefix part, and last_sig_coeff_y_suffix, which is the suffix part.

[00578] When the location of the last non-zero coefficient is determined, information indicating whether residual coefficients earlier than the last non-zero coefficient in the scanning order are non-zero coefficients may be encoded (S4104). The information may be a 1-bit flag sig_coeff_flag. The value of the non-zero coefficient flag sig_coeff_flag can be set to 0 when the residual coefficient is 0, and the value of the non-zero coefficient flag sig_coeff_flag can be set to 1 when the residual coefficient is 1. The encoding of the non-zero coefficient flag sig_coeff_flag for the last non-zero coefficient can be skipped. When encoding of the non-zero coefficient flag sig_coeff_flag is omitted, the corresponding residual coefficient is assumed to be non-zero.

[00579] Information regarding the location of the last non-zero coefficient for the transform skip coefficient may not be encoded. In this case, a non-zero coefficient flag sig_coeff_flag may be encoded for all conversion skip coefficients in the block.

[00580] Alternatively, information indicating whether information is encoded regarding the location of the last non-zero coefficient may be encoded and transmitted. The information may be a 1-bit flag. The decoder may determine whether to decode information regarding the location of the last non-zero coefficient in accordance with the value of the flag. When the location of the last non-zero coefficient is not decoded, the non-zero coefficient flag may be decoded for all transform skip coefficients. On the other hand, when the location of the last non-zero coefficient is decoded, information indicating whether transform skip coefficients scanned earlier than the last non-zero coefficient are non-zero coefficients may be encoded.

[00581] The DC component of the conversion coefficient or the conversion skip coefficient may not be set to zero. In this case, the DC component may indicate the last scanned sample or the sample located in the upper left corner of the block. For a DC component, the encoding of the non-zero coefficient flag sig_coeff_flag may be omitted. When encoding of the non-zero coefficient flag sig_coeff_flag is omitted, the corresponding residual coefficient is assumed to be non-zero.

[00582] When the residual coefficient is non-zero, information indicating the absolute value of the residual coefficient and information indicating the sign of the residual coefficient may be encoded (S4105). The process of encoding information indicating the absolute value of the residual coefficient will be described in detail with reference to FIG. 45.

[00583] Encoding (S4106 and S4107) of the residual coefficient may be sequentially performed on the subtransform elements included in the current block and all residual coefficients after the last non-zero coefficient.

[00584] In FIG. 45 is a flowchart of a process for encoding the absolute value of a residual coefficient.

[00585] When the absolute value of the residual coefficient is greater than 0, information indicating whether the residual coefficient or the residual coefficient is an even number or an odd number can be encoded (S4501). In this case, the residual coefficient can be specified as the absolute value of the residual coefficient minus 1. The information can be a 1-bit parity flag. As an example, a par_level_flag syntax element value of 0 means that the residual coefficient or remainder coefficient is an even number, and a par_level_flag syntax element value equal to 1 means that the residual coefficient or remainder coefficient is an odd number. The value of the par_level_flag syntax element can be determined using Equation 30 below.

[00586] [Equation 30]

[00587] In Equation 30, Tcoeff represents the residual coefficient, and abs() represents the absolute value function.

[00588] The adjusted residual coefficient can be obtained (S4502) by dividing the residual coefficient or remainder coefficient by 2 or by applying a bit shift operation to the residual coefficient or residual coefficient. In detail, the adjusted residual coefficient can be set to the quotient obtained by dividing the residual coefficient by 2, or the adjusted residual coefficient can be set to the value obtained by shifting the residual coefficient to the right by 1.

[00589] As an example, the adjusted residual factor can be obtained using Equation 31 below.

[00590] [Equation 31]

[00591] In Equation 31, ReRemLevel represents the adjusted residual coefficient, and RemLevel represents the residual coefficient.

[00592] Information indicating the size of the adjusted residual factor may then be encoded. The information indicating the size of the adjusted residual factor may include information indicating whether the adjusted residual factor is greater than N. In this case, N represents a natural number such as 1, 2, 3 and 4.

[00593] As an example, information indicating whether the value of the adjusted residual coefficient is greater than 1 may be encoded. The information may be a 1-bit flag rem_abs_gt1_flag.

[00594] When the residual coefficient is 0 or 1, the value of rem_abs_gt1_flag can be set to 0. That is, when the residual coefficient is 1 or 2, the value of rem_abs_gt1_flag can be set to 0. In this case, par_level_flag can be set to 0 when the coefficient the remainder is 0, and par_level_flag can be set to 1 when the remainder factor is 1.

[00595] When the adjusted residual coefficient is 2 or more (S4504), the value of rem_abs_gt1_flag may be set to 1, and information indicating whether the value of the adjusted residual coefficient is greater than 2 can be encoded (S4505). The information may be 1-bit flag rem_abs_gt2_flag.

[00596] When the residual coefficient is 1 or 2, the value of rem_abs_gt2_flag can be set to 0. That is, when the residual coefficient is 3 or 4, the value of rem_abs_gt2_flag can be set to 0. In this case, par_level_flag can be set to 2 when the coefficient the remainder is 0, and par_level_flag can be set to 1 when the remainder factor is 3.

[00597] When the adjusted residual coefficient is greater than 2, residual value information indicating the corrected residual coefficient minus 2 may be encoded (S4506). That is, a value obtained by subtracting 5 from the absolute value of the residual coefficient may be encoded as residual value information, and then divide the result of the subtraction by 2.

[00598] Although not shown, the residual coefficient may be further encoded using a flag indicating whether the adjusted residual coefficient is greater than 3 (eg, rem_abs_gt3_flag) or a flag indicating whether the adjusted residual coefficient is greater than 4 (eg, rem_abs_gt4_flag ). In this case, the residual value can be set to the adjusted residual coefficient minus the maximum value. The maximum value represents the maximum N applied to rem_abs_gtN_flag.

[00599] Instead of flags for comparing the value of the adjusted residual coefficient to a specific value, flags may be used to compare the absolute value of the adjusted coefficient or the residual coefficient to a specific value. As an example, instead of rem_abs_gt1_flag, gr2_flag may be used to indicate whether the absolute value of the residual coefficient is greater than 2, and instead of rem_abs_gt2_flag, gr4_flag may be used to indicate whether the absolute value of the residual coefficient is greater than 4.

[00600] Table 14 simply presents the process of encoding residual coefficients using syntax elements.

[00601] [Table 14]

[00602] In the above example, the residual coefficient may be encoded using par_level_flag and at least one rem_abs_gtN_flag (where N represents a natural number such as 1, 2, 3 and 4).

[00603] rem_abs_gtN_flag represents whether the residual coefficient is greater than 2N. For a residual coefficient of 2N-1 or 2N, rem_abs_gt(N-1)_flag is set to true and rem_abs_gtN_flag is set to false. In addition, the par_level_flag value can be set to 0 for a 2N-1 residual coefficient, and the par_level_flag value can be set to 1 for a 2N residual coefficient. That is, residual coefficients less than or equal to 2N can be encoded using rem_abs_gtN_flag and par_level_flag.

[00604] For residual coefficients greater than or equal to 2MAX+1, residual value information may be encoded indicating the value obtained by dividing the difference from 2MAX by 2. In this case, MAX represents the maximum value of N. As an example, when rem_abs_gt1_flag and rem_abs_gt2_flag, MAX can be 2.

[00605] The decoder may also decode the residual coefficients in the order shown in FIG. 45. In detail, the decoder may locate the last non-zero coefficient and may decode a sig_coeff_flag for each residual coefficient scanned before the last non-zero coefficient.

[00606] When sig_coeff_flag is true, the decoder can decode the par_level_flag of the corresponding residual coefficient. In addition, the decoder can decode the rem_abs_gt1_flag of the corresponding residual coefficient. In this case, rem_abs_gtN_flag may be further decoded depending on the value of rem_abs_gt(N-1)_flag. As an example, the decoder may decode rem_abs_gtN_flag when the value of rem_abs_gt(N-1)_flag is 1. For example, when the value of rem_abs_gt1_flag for the residual coefficient is 1, the decoder may further analyze rem_abs_gt2_flag for the residual coefficient. When the value of rem_abs_gt(MAX)_flag is 1, the decoder can decode the residual value information.

[00607] When the value of the residual coefficient rem_abs_gtN_flag is 0, the value of the residual coefficient can be determined to be 2N-1 or 2N depending on the value of par_level_flag. In detail, the residual coefficient can be set to 2N-1 when par_level_flag is 0, and the residual coefficient can be set to 2N when par_level_flag is 1.

[00608] For example, when rem_abs_gt1_flag is 0, the absolute value of the residual coefficient can be set to 1 or 2 depending on the value of par_level_flag. In detail, the absolute value of the residual coefficient is 1 when the value of par_level_flag is 0, and the absolute value of the residual coefficient is 2 when the value of par_level_flag is 1.

[00609] For example, when rem_abs_gt2_flag is 0, the absolute value of the residual coefficient can be set to 3 or 4 depending on the value of par_level_flag. In detail, the absolute value of the residual coefficient is 3 when the value of par_level_flag is 0, and the absolute value of the residual coefficient is 4 when the value of par_level_flag is 1.

[00610] When decoding residual value information, the residual coefficient may be set to 2(MAX+R)-1 or 2(MAX+R) depending on the value of par_level_flag. Here, R represents the value indicated by the residual value information. As an example, the residual coefficient can be set to 2(MAX+R)-1 when par_level_flag is 0, and the residual coefficient can be set to 2(MAX+R) when par_level_flag is 1. As an example, when MAX is 2, the residual coefficient can be obtained using Equation 32 below.

[00611] [Equation 32]

[00612] When the residual coefficient is encoded in the example shown in FIG. 45, a parity flag may be encoded for each non-zero coefficient. As an example, even when the residual coefficient is 1, par_level_flag and rem_abs_gt1_flag must be encoded. The above encoding method may cause an increase in the number of bits required to encode residual coefficients having an absolute value of 1. To solve the problem, information indicating whether the residual coefficient is greater than 1 may be encoded first, and when the residual coefficient is 1, a parity flag may be encoded.

[00613] In FIG. 46 is a flowchart of a process for encoding the absolute value of a residual coefficient.

[00614] For a non-zero residual coefficient, gr1_flag information may be encoded (S4601) indicating whether the absolute value of the residual coefficient is greater than 1. gr1_flag may be set to 0 when the residual coefficient is 1, and gr1_flag may be set to 1 when the residual coefficient is coefficient is greater than 1.

[00615] When the absolute value of the residual coefficient is greater than 1, a parity flag indicating whether the residual coefficient or the remainder coefficient is an even number or an odd number may be encoded (S4602 and S4603). In this case, the residual coefficient can be set to the residual coefficient minus 2. As an example, par_level_flag can be obtained using Equation 33 below.

[00616] [Equation 33]

[00617] The adjusted residual coefficient may be obtained by dividing the residual coefficient or remainder coefficient by 2 or by bit shifting the residual coefficient or residual coefficient to the right by 1, and then information indicating whether the corrected residual coefficient is greater than 1 may be encoded (S4604). As an example, for a residual coefficient whose gr1_flag is 1, a rem_abs_gt1_flag may be encoded indicating whether the adjusted residual coefficient is greater than 1.

[00618] When the residual coefficient is 0 or 1, the value of rem_abs_gt1_flag can be set to 0. That is, when the residual coefficient is 2 or 3, the value of rem_abs_gt1_flag can be set to 0. In this case, par_level_flag can be set to 0 when the adjusted the residual coefficient is 0, and par_level_flag can be set to 1 when the residual coefficient is 1.

[00619] When the adjusted residual coefficient is 2 or more (S4605), the value of rem_abs_gt1_flag may be set to 1, and information indicating whether the value of the adjusted residual coefficient is greater than 2 can be encoded (S4606). As an example, for the residual coefficient , whose rem_abs_gt1_flag is 1, may be encoded with a rem_abs_gt2_flag indicating whether the adjusted residual factor is greater than 2.

[00620] When the residual coefficient is 2 or 3, the value of rem_abs_gt2_flag can be set to 1. That is, when the residual coefficient is 4 or 5, the value of rem_abs_gt2_flag can be set to 0. In this case, par_level_flag can be set to 0 when the coefficient the remainder is 2, and par_level_flag can be set to 1 when the remainder factor is 3.

[00621] When the adjusted residual coefficient is greater than 2 (S4607), residual value information indicating the adjusted residual coefficient minus 2 may be encoded (S4608). That is, a value obtained by subtracting 6 from the absolute value of the residual may be encoded as residual value information. coefficient and then dividing the subtraction result by 2.

[00622] The residual coefficient may be further encoded using a flag indicating whether the adjusted residual coefficient is greater than 3 (eg, rem_abs_gt3_flag) or a flag indicating whether the adjusted residual coefficient is greater than 4 (eg, rem_abs_gt4_flag). In this case, the residual value can be set to the adjusted residual coefficient minus the maximum value. The maximum value represents the maximum N applied to rem_abs_gtN_flag.

[00623] Instead of flags for comparing the value of the adjusted residual coefficient to a specific value, flags may be used to compare the absolute value of the adjusted coefficient or the residual coefficient to a specific value. As an example, instead of rem_abs_gt1_flag, gr3_flag may be used to indicate whether the absolute value of the residual coefficient is greater than 3, and instead of rem_abs_gt2_flag, gr5_flag may be used to indicate whether the absolute value of the residual coefficient is greater than 5.

[00624] Table 15 simply presents the process of encoding residual coefficients using syntax elements.

[00625] [Table 15]

[00626] The decoder may also decode the residual coefficients in the order shown in FIG. 46. In detail, the decoder may locate the last non-zero coefficient and may decode a sig_coeff_flag for each residual coefficient scanned before the last non-zero coefficient.

[00627] When sig_coeff_flag is true, the decoder can decode the gr1_flag of the corresponding residual coefficient. The decoder may determine that the absolute value of the corresponding residual coefficient is 1 when gr1_flag is 0, and may decode the par_level_flag of the corresponding residual coefficient when gr1_flag is 1. The decoder may then decode the rem_abs_gt1_flag of the corresponding residual coefficient. In this case, rem_abs_gtN_flag may be further decoded depending on the value of rem_abs_gt(N-1)_flag. As an example, the decoder may decode rem_abs_gtN_flag when the value of rem_abs_gt(N-1)_flag is 1. For example, when the value of rem_abs_gt1_flag for the residual coefficient is 1, the decoder may further analyze rem_abs_gt2_flag for the residual coefficient. When the value of rem_abs_gt(MAX)_flag is 1, the decoder can decode the residual value information.

[00628] When the rem_abs_gtN_flag value of the residual coefficient is 0, the value of the residual coefficient can be determined to be 2N or 2N+1 depending on the value of par_level_flag. In detail, the residual coefficient can be set to 2N when par_level_flag is 0, and the residual coefficient can be set to 2N+1 when par_level_flag is 1.

[00629] For example, when rem_abs_gt1_flag is 0, the absolute value of the residual coefficient can be set to 2 or 3 depending on the value of par_level_flag. In detail, the absolute value of the residual coefficient is 2 when the value of par_level_flag is 0, and the absolute value of the residual coefficient is 3 when the value of par_level_flag is 1.

[00630] For example, when rem_abs_gt2_flag is 0, the absolute value of the residual coefficient can be set to 4 or 5 depending on the value of par_level_flag. In detail, the absolute value of the residual coefficient is 4 when the value of par_level_flag is 0, and the absolute value of the residual coefficient is 5 when the value of par_level_flag is 1.

[00631] When decoding residual value information, the residual coefficient may be set to 2(MAX+R) or 2(MAX+R)+1 depending on the value of par_level_flag. Here, R represents the value of the residual value information. As an example, the residual coefficient can be set to 2(MAX+R) when par_level_flag is 0, and the residual coefficient can be set to 2(MAX+R)+1 when par_level_flag is 1.

[00632] As another example, a parity flag may be encoded only when the residual coefficient value is greater than 2. As an example, after encoding the information indicating whether the residual coefficient value is greater than 1 and the information indicating whether the residual coefficient value is coefficient greater than 2, when it is determined that the value of the residual coefficient is greater than 2, a parity flag for the corresponding residual coefficient may be encoded.

[00633] In FIG. 47 is a flowchart of a process for encoding the absolute value of a residual coefficient.

[00634] For a non-zero residual coefficient, gr1_flag information may be encoded (S4701) indicating whether the absolute value of the residual coefficient is greater than 1. gr1_flag may be set to 0 when the residual coefficient is 1, and gr1_flag may be set to 1 when the residual coefficient is coefficient is greater than 1.

[00635] For a residual coefficient whose absolute value is greater than 1, gr2_flag information indicating whether the absolute value of the residual coefficient is greater than 2 may be encoded (S4702 and S4703). gr2_flag may be set to 0 when the residual coefficient is 2, and gr2_flag can be set to 1 when the residual coefficient is greater than 2.

[00636] When the absolute value is greater than 2, a parity flag indicating whether the remainder coefficient or the remainder coefficient is an even number or an odd number may be encoded (S4704 and S4705). In this case, the residual coefficient can be set to the residual coefficient minus 3. As an example, par_level_flag can be obtained using Equation 34 below.

[00637] [Equation 34]

[00638] The adjusted residual coefficient may be obtained by dividing the residual coefficient or residual coefficient by 2 or by bit shifting the residual coefficient or residual coefficient to the right by 1, and then information indicating whether the adjusted residual coefficient is greater than 1 can be encoded. For example, for a residual coefficient whose gr1_flag is 1, a rem_abs_gt1_flag indicating whether the adjusted residual coefficient is greater than 1 may be encoded (S4706).

[00639] When the residual coefficient is 0 or 1, the value of rem_abs_gt1_flag can be set to 0. That is, when the residual coefficient is 3 or 4, the value of rem_abs_gt1_flag can be set to 0. In this case, par_level_flag can be set to 0 when the adjusted the residual coefficient is 0, and par_level_flag can be set to 1 when the residual coefficient is 1.

[00640] When the adjusted residual coefficient is 2 or more (S4707), the value of rem_abs_gt1_flag may be set to 1, and information indicating whether the value of the adjusted residual coefficient is greater than 2 can be encoded (S4708). As an example, for the residual coefficient , whose rem_abs_gt1_flag is 1, may be encoded with a rem_abs_gt2_flag indicating whether the adjusted residual factor is greater than 2.

[00641] When the residual coefficient is 2 or 3, the value of rem_abs_gt2_flag can be set to 1. That is, when the residual coefficient is 5 or 6, the value of rem_abs_gt2_flag can be set to 0. In this case, par_level_flag can be set to 0 when the coefficient the remainder is 2, and par_level_flag can be set to 1 when the remainder factor is 3.

[00642] When the adjusted residual coefficient is greater than 2, a residual value equal to the adjusted residual coefficient minus 2 may be encoded (S4709 and S4710). That is, a value obtained by subtracting 7 from the absolute value of the residual coefficient and then dividing may be encoded as the residual value. the result of subtraction by 2.

[00643] The residual coefficient may be further encoded using a flag indicating whether the adjusted residual coefficient is greater than 3 (eg, rem_abs_gt3_flag) or a flag indicating whether the adjusted residual coefficient is greater than 4 (eg, rem_abs_gt4_flag). In this case, the residual value can be set to the adjusted residual coefficient minus the maximum value. The maximum value represents the maximum N applied to rem_abs_gtN_flag.

[00644] Instead of flags for comparing the value of the adjusted residual coefficient to a specific value, flags may be used to compare the absolute value of the adjusted coefficient or the residual coefficient to a specific value. As an example, instead of rem_abs_gt1_flag, gr4_flag may be used to indicate whether the absolute value of the residual coefficient is greater than 4, and instead of rem_abs_gt2_flag, gr6_flag may be used to indicate whether the absolute value of the residual coefficient is greater than 6.

[00645] The decoder may also decode the residual coefficients in the same order as shown in FIG. 47. In detail, the decoder may locate the last non-zero coefficient and may decode a sig_coeff_flag for each residual coefficient scanned before the last non-zero coefficient.

[00646] When sig_coeff_flag is true, the decoder can decode the gr1_flag of the corresponding residual coefficient. The decoder may determine that the absolute value of the corresponding residual coefficient is 1 when gr1_flag is 0, and may decode gr2_flag when gr1_flag is 1. The decoder may determine that the absolute value of the corresponding residual coefficient is 2 when gr2_flag is 0, and may decode par_level_flag the corresponding residual coefficient when gr2_flag is 1. The decoder can then decode the rem_abs_gt1_flag of the corresponding residual coefficient. In this case, rem_abs_gtN_flag may be further decoded depending on the value of rem_abs_gt(N-1)_flag. As an example, the decoder may decode rem_abs_gtN_flag when the value of rem_abs_gt(N-1)_flag is 1. For example, when the value of rem_abs_gt1_flag for the residual coefficient is 1, the decoder may further analyze rem_abs_gt2_flag for the residual coefficient. When the value of rem_abs_gt(MAX)_flag is 1, the decoder can decode the residual value information.

[00647] When the value of the residual coefficient rem_abs_gtN_flag is 0, the value of the residual coefficient can be determined to be 2N+1 or 2(N+1) depending on the value of par_level_flag. In detail, the residual coefficient can be set to 2N+1 when par_level_flag is 0, and the residual coefficient can be set to 2(N+1) when par_level_flag is 1.

[00648] For example, when rem_abs_gt1_flag is 0, the absolute value of the residual coefficient can be set to 3 or 4 depending on the value of par_level_flag. In detail, the absolute value of the residual coefficient is 3 when the value of par_level_flag is 0, and the absolute value of the residual coefficient is 4 when the value of par_level_flag is 1.

[00649] For example, when rem_abs_gt2_flag is 0, the absolute value of the residual coefficient can be set to 5 or 6 depending on the value of par_level_flag. In detail, the absolute value of the residual coefficient is 5 when the value of par_level_flag is 0, and the absolute value of the residual coefficient is 6 when the value of par_level_flag is 1.

[00650] When decoding residual value information, the residual coefficient may be set to 2(MAX+R) or 2(MAX+R)+1 depending on the value of par_level_flag. Here, R represents the value of the residual value information. As an example, the residual coefficient can be set to 2(MAX+R) when par_level_flag is 0, and the residual coefficient can be set to 2(MAX+R)+1 when par_level_flag is 1.

[00651] At least one of a number or types of comparison flags may be defined to compare the adjusted remainder coefficients to a particular value based on at least one of the size or shape of the current block, the presence of a conversion skip, the basis of the conversion, the number of non-zero coefficients, or the location of the latter non-zero coefficient. As an example, when encoding the transform coefficient, only rem_abs_gt1_flag can be used. On the other hand, when encoding the transform skip factor, rem_abs_gt1_flag and rem_abs_gt2_flag can be used.

[00652] Alternatively, in a 4x4 sub-transform element, the number of rem_abs_gt1_fag flags can be set to up to 8, and the number of rem_abs_gt2_flag flags can be set to up to 1. Alternatively, when the number of non-zero coefficient flags is (16-N), the number of rem_abs_gt1_flag flags can be set to up to 8+(N/2), and the number of rem_abs_gt2_flags can be set to up to 1+(N-(N/2)).

[00653] When obtaining a reconstructed block of the current block, the loss of information that occurs during quantization and encoding can be reduced by using in-loop filtering. The filter in the loop may comprise at least one of a deblocking filter, an adaptive sample offset filter (SAO), or an adaptive loop filter (ALF). The reconstructed block before applying the filter in the loop will be called the first reconstructed block, and the reconstructed block after applying the filter in the loop will be called the second reconstructed block.

[00654] The second reconstructed block may be obtained by applying at least one of a deblocking filter, SAO, or ALF to the first reconstructed block. In this case, SAO or ALF can be applied after applying the deblocking filter.

[00655] The deblocking filter is designed to mitigate video quality degradation (blocking artifact) that occurs at the block edge when performing quantization on block elements. To apply a deblocking filter, a block quality score (BS) between the first reconstructed block and an adjacent reconstructed block can be determined.

[00656] In FIG. 48 is a flowchart showing the process of determining the quality of a block.

[00657] In the example shown in FIG. 48, P represents the first reconstructed block, and Q represents the adjacent reconstructed block. In this case, the adjacent reconstructed block may be a block adjacent to the current block to the left or above.

[00658] In the example shown in FIG. 48, it is shown that the block quality is determined taking into account the prediction modes P and Q, whether non-zero transform coefficients are included, whether prediction carried out between pictures is performed using the same reference picture, or whether the difference value between motion vectors greater than or equal to the threshold value.

[00659] Based on the quality of the block, it can be determined whether to apply a deblocking filter. As an example, filtering may not be performed when the block quality score is 0.

[00660] SAO is designed to reduce the ringing artifact that occurs when performing frequency domain quantization. SAO can be performed by adding or subtracting an offset determined given the design of the first reconstructed block. The method for determining the offset includes edge offset (EO) or stripe offset (BO). EO specifies a way to determine the offset of the current sample according to the pattern of nearby pixels. BO specifies a way to apply a common offset to a set of pixels having similar brightness values in an area. In detail, the brightness of the pixels is divided into 32 equal sections, and pixels having similar brightness values can be set as one set. As an example, four adjacent bands of 32 bands can be set as one group, and the same offset value can be applied to the samples belonging to the four bands.

[00661] ALF is a method of generating a second reconstructed block by applying a filter of a predetermined size or shape to a first reconstructed block or to a reconstructed block to which a deblocking filter has been applied. Equation 35 below provides an example application of ALF.

[00662] [Equation 35]

[00663] One of the predefined candidate filters may be selected in pixels, code tree elements, encoding blocks, prediction blocks, or transform blocks. Candidate filters may vary in size or shape.

[00664] In FIG. 49 shows predefined candidate filters.

[00665] In the example shown in FIG. 49, at least one of a 5x5 diamond shape, a 7x7 diamond shape, or a 9x9 diamond shape can be selected.

[00666] For the chrominance component, only a 5x5 diamond shape can be used.

[00667] The application of embodiments that have been described as directed to a decoding process or an encoding process to a decoding process or an encoding process is within the scope of the present invention. Changing the predetermined order in which the embodiments have been described to an order different from that described above is also within the scope of the present invention.

[00668] Although the above embodiments have been described in terms of a number of steps or sequences of operations, the steps or sequences of operations do not limit the order of the present invention in a time series and may be performed simultaneously or in other orders as necessary. In addition, each of the components (eg, elements, modules, etc.) constituting a block diagram in the above-described embodiments may be implemented by a hardware device or software, and a plurality of components may be combined and implemented by a single hardware device or software provision. The above-described embodiments may be implemented in the form of program instructions, which may be executed by various computer means and recorded in a computer-readable storage medium. The computer-readable storage medium may comprise a program instruction, a data file, a data structure, and the like. separately or in combination. Examples of computer readable storage media include magnetic media such as hard disk, floppy disk and magnetic tape, optical media such as compact disc read only memory (CD-ROM) and digital versatile disk (DVD), magneto-optical media such as flexible magneto-optical disk, and hardware devices such as ROM, random access memory (RAM), and flash memory, which are specifically designed to store and execute software commands. The hardware device may be configured to operate as one or more software modules to perform the operations of the present invention, and vice versa.

[Industrial applicability]

[00669] The present invention can be applied to an electronic device for encoding or decoding video.

Claims (25)

1. A method for video decoding, including the following steps: analyzing a non-zero flag indicating whether the residual coefficient is non-zero from the bit stream, wherein when encoding of the non-zero residual coefficient flag is omitted, the residual coefficient is considered to be non-zero and the location of the residual coefficient is determined as the location of the last non-zero residual coefficient; analyzing the absolute value information to determine the absolute value of the residual coefficient from the bit stream, when the non-zero flag indicates that the residual coefficient is non-zero; And determining the absolute value of the residual coefficient based on information about the absolute value, wherein the absolute value information includes a residual coefficient comparison flag indicating whether the residual coefficient is greater than the first value; the parity flag is further parsed from the bitstream only when the residual coefficient is greater than the first value; and a parity flag indicates whether the residual coefficient value is an even number or an odd number. 2. The method according to claim 1, characterized in that the first adjusted residual coefficient comparison flag indicating whether the adjusted residual coefficient obtained by bit shifting the residual coefficient to the right by 1 than the second value is further analyzed when the residual coefficient is greater than first value. 3. The method of claim 2, wherein N is the second value and the residual coefficient is determined to be 2N or 2N+1 depending on the parity flag when the adjusted residual coefficient is less than or equal to the second value. 4. The method of claim 2, wherein the second adjusted residual ratio comparison flag indicating whether the adjusted residual ratio is greater than the third value is further analyzed when the adjusted residual ratio is greater than the second value. 5. Method according to claim 2, characterized in that the residual value information is further analyzed when the adjusted residual ratio is greater than the second value, and the residual value information contains the value obtained by subtracting the second value from the adjusted residual coefficient. 6. Video encoding method, including the following steps: encoding a non-zero flag indicating whether the residual coefficient is non-zero, while encoding the non-zero flag of the last non-zero residual coefficient is omitted; And encoding absolute value information to determine the absolute value of the residual coefficient when the residual coefficient is non-zero, wherein the absolute value information includes a residual coefficient comparison flag indicating whether the residual coefficient is greater than the first value; a parity flag for the residual coefficient is further encoded only when the residual coefficient is greater than the first value; and a parity flag indicates whether the residual coefficient value is an even number or an odd number. 7. The method of claim 6, wherein the first adjusted residual coefficient comparison flag indicating whether the adjusted residual coefficient obtained by bit shifting the residual coefficient to the right by 1 than the second value is further encoded when the residual coefficient is greater than first value. 8. The method of claim 7, wherein N is the second value and the residual coefficient is determined to be 2N or 2N+1 depending on the parity flag when the adjusted residual coefficient is less than or equal to the second value. 9. The method of claim 7, wherein a second adjusted residual ratio comparison flag indicating whether the adjusted residual ratio is greater than the third value is further encoded when the adjusted residual ratio is greater than the second value. 10. Method according to claim 7, characterized in that the residual value information is further encoded when the adjusted residual coefficient is greater than the second value, and the residual value information contains the value obtained by subtracting the second value from the adjusted residual coefficient.