Video coding method and apparatus using adaptive parameter set

Abstract

A video coding method and apparatus using an adaptive parameter set are provided. A video decoding method and apparatus according to the present disclosure may obtain a transform coefficient of a current block, perform inverse quantization on the transform coefficient based on a quantization-related parameter of an adaptive parameter set to obtain an inversely quantized transform coefficient, and reconstruct a residual block of the current block based on the inversely quantized transform coefficient.

Description

[0001] This application is a divisional application of a Chinese patent application filed on November 23, 2021, with the application number 202080038371.2 and the invention title "Video Coding Method and Apparatus Using Adaptive Parameter Sets". The international filing date of the parent application is May 22, 2020, the international application number is PCT / KR2020 / 006704, and the priority date is May 24, 2019. Technical Field

[0002] The present disclosure relates to video encoding / decoding methods and apparatuses. Background Art

[0003] With the recent increase in the demand for high-resolution and high-definition videos, there has been a need for efficient video compression technologies for next-generation video services. Based on this need, since October 2015, ISO / IEC MPEG and ITU-T VCEG, which jointly standardized the H.264 / AVC and HEVC video compression standards, have formed the JVET (Joint Video Exploration Team) and conducted research and exploration to establish a new video compression standard. In April 2018, with the evaluation of the responses to the CfP (Call for Proposal) for the new video compression standard, the new video compression standardization began.

[0004] In video compression technologies, the block partitioning structure refers to the unit for performing encoding and decoding and the unit to which main encoding and decoding techniques such as prediction and transformation are applied. As video compression technologies have developed, the size of the blocks for encoding and decoding has gradually increased, and more various partitioning types are supported as the block partitioning types. In addition, video compression is performed not only using the units for encoding and decoding but also using the units that are subdivided according to the role of the blocks.

[0005] In the HEVC standard, unit blocks subdivided according to a quadtree-based block partitioning structure and the roles for performing prediction and transformation are used to perform video encoding and decoding. In addition to the quadtree-based block partitioning structure, various types of block partitioning structures have been proposed, such as QTBT (Quad Tree plus Binary Tree) in the form of a combination of a quadtree and a binary tree and MTT (Multi-Type Tree) in combination with a ternary tree, to improve video decoding efficiency. By supporting various block sizes and various types of block partitioning structures, a picture is divided into multiple blocks, and information such as decoding modes, motion information, and intra prediction direction information corresponding to each block is expressed in various ways as units of decoding units. Therefore, the number of bits for expressing such information significantly increases. Summary of the Invention

[0006] Technical Problem

[0007] An object of the present disclosure is to improve the decoding efficiency of video signals.

[0008] An object of the present disclosure is to provide a method and an apparatus for effectively defining / managing various parameters to be applied in units of pictures or slices.

[0009] An object of the present disclosure is to provide a method and an apparatus for obtaining a scaling list for quantization / inverse quantization.

[0010] Technical Solution

[0011] To solve the above problems, the present invention provides a video decoding method and apparatus using an adaptive parameter set.

[0012] A video decoding method and apparatus according to the present disclosure may obtain transform coefficients of a current block by decoding a bitstream, obtain inverse-quantized transform coefficients by performing inverse quantization on the obtained transform coefficients based on quantization-related parameters included in the bitstream, and reconstruct a residual block of the current block based on the inverse-quantized transform coefficients. Here, the quantization-related parameters may be obtained from an adaptation parameter set (APS) of the bitstream.

[0013] In a video decoding method and apparatus according to the present disclosure, obtaining the inverse-quantized transform coefficients includes: obtaining an inverse quantization scaling list based on the quantization-related parameters, obtaining a scaling factor based on the scaling list and a predetermined weight, and applying the obtained scaling factor to the transform coefficients.

[0014] In a video decoding method and apparatus according to the present disclosure, the quantization-related parameters may include at least one of a copy mode flag, a prediction mode flag, an increment identifier, or difference coefficient information.

[0015] In a video decoding method and apparatus according to the present disclosure, the weight may be obtained from a weight candidate list predefined in a decoding device.

[0016] In a video decoding method and apparatus according to the present disclosure, the number of weight candidate lists predefined in the decoding device is two or more than two, and one of the weight candidate lists may be selectively used based on coding parameters of the current block.

[0017] In the video decoding method and apparatus according to the present disclosure, an adaptive parameter set is a syntax structure including a parameter set to be used in a predetermined picture unit, and the parameter set includes at least one of adaptive loop filter (ALF) related parameters, parameters related to a mapping model of a shaper (luma mapping with chroma scaling), or quantization related parameters.

[0018] In the video decoding method and apparatus according to the present disclosure, the adaptive parameter set may further include at least one of an identifier of the adaptive parameter set or adaptive parameter set type information.

[0019] In the video decoding method and apparatus according to the present disclosure, the same identifier is assigned to different adaptive parameter set types, and different lists may be used to manage the adaptive parameter sets for each adaptive parameter set type.

[0020] The video encoding method and apparatus according to the present disclosure may obtain transform coefficients of a current block, perform inverse quantization on the transform coefficients based on predetermined quantization related parameters to obtain inverse quantized transform coefficients, and reconstruct a residual block of the current block based on the inverse quantized transform coefficients. Here, the quantization related parameters may be transmitted in an adaptive parameter set (APS) of a bitstream.

[0021] A computer-readable recording medium stores a bitstream decoded by a video decoding method according to the present disclosure. The video decoding method includes: decoding the bitstream to obtain transform coefficients of a current block, obtaining inverse quantized transform coefficients by performing inverse quantization on the obtained transform coefficients based on quantization related parameters included in the bitstream, and reconstructing a residual block of the current block based on the inverse quantized transform coefficients. Here, the quantization related parameters may be obtained from an adaptive parameter set (APS) of the bitstream.

[0022] According to an aspect of the present invention, there is provided a video decoding method, including: generating a prediction block of a current block based on intra prediction or inter prediction; obtaining transform coefficients of the current block from a bitstream; obtaining inverse quantized transform coefficients by performing inverse quantization on the transform coefficients based on quantization related parameters included in the bitstream; generating a residual block of the current block by performing inverse transform on the inverse quantized transform coefficients, and reconstructing the current block based on the prediction block and the residual block, where the quantization related parameters are obtained from an adaptive parameter set (APS) of the bitstream, and where obtaining the inverse quantized transform coefficients includes: obtaining a scaling list for the inverse quantization based on the quantization related parameters; obtaining a scaling factor based on the scaling list and a predetermined weight; and applying the scaling factor to the transform coefficients.

[0023] According to one aspect of the present invention, there is provided a video encoding method, including: generating a prediction block of a current block based on intra prediction or inter prediction; generating a residual block of the current block based on the prediction block; obtaining transform coefficients of the current block by performing a transform on the residual block of the current block; performing quantization on the transform coefficients to obtain quantized transform coefficients; and encoding the quantized transform coefficients, wherein quantization-related parameters of the current block are encoded in an adaptive parameter set (APS) of a bitstream, and wherein performing the quantization on the transform coefficients includes: obtaining a scaling list for the quantization based on the quantization-related parameters; obtaining a scaling factor based on the scaling list and a predetermined weight; and applying the scaling factor to the transform coefficients.

[0024] According to one aspect of the present invention, there is provided a method for transmitting a bitstream, including: generating a prediction block of a current block based on intra prediction or inter prediction; generating a residual block of the current block based on the prediction block; obtaining transform coefficients of the current block by performing a transform on the residual block of the current block; performing quantization on the transform coefficients to obtain quantized transform coefficients; encoding the quantized transform coefficients to generate the bitstream; and transmitting the bitstream, wherein quantization-related parameters of the current block are encoded in the adaptive parameter set (APS) of the bitstream, and wherein performing the quantization on the transform coefficients includes: obtaining a scaling list for the quantization based on the quantization-related parameters; obtaining a scaling factor based on the scaling list and a predetermined weight; and applying the scaling factor to the transform coefficients.

[0025] Advantageous Effects

[0026] According to the present disclosure, the video signal decoding efficiency can be improved by using an adaptive parameter set.

[0027] According to the present disclosure, various parameters for each type of adaptive parameter set (APS type) can be effectively managed by using an adaptive parameter set.

[0028] According to the present disclosure, a scaling list for quantization / inverse quantization can be effectively obtained through various modes. Brief Description of the Drawings

[0029] Figure 1 is a block diagram showing an image encoding device according to the present disclosure.

[0030] Figure 2 is a block diagram showing an image decoding device according to the present disclosure.

[0031] Figure 3 shows an embodiment of a syntax table of an adaptive parameter set (APS).

[0032] Figure 4 Shows an embodiment of a syntax table for transmitting and parsing quantization-related parameters.

[0033] Figure 5 Shows an embodiment of a method for reconstructing a residual block based on quantization-related parameters.

[0034] Figure 6 Is a diagram showing an embodiment of an APS syntax table of an APS type for weight prediction added.

[0035] Figure 7 Is a diagram showing another embodiment of an APS syntax table of an APS type for weight prediction added.

[0036] Figure 8 Is a diagram showing another embodiment of an APS syntax table of an APS type for weight prediction added.

[0037] Figure 9 Is a diagram showing an embodiment of a syntax table for transmitting and parsing parameters for weight prediction.

[0038] Figure 10 Is a diagram showing an embodiment of an APS syntax table of an APS type for block partitioning structure added.

[0039] Figure 11 and Figure 12 Shows an embodiment of a syntax table of parameters of a block structure additionally signaled or parsed in the case where the current APS type is parameters of a block partitioning structure.

[0040] Figure 13 Is a diagram showing a part of a syntax table for a slice header to show an embodiment of APS signaling or parsing for a block partitioning structure in the slice header.

[0041] Figure 14 Is a diagram showing the concept of managing APS using different lists according to the APS type. Detailed Description

[0042] To solve the above problems, the present invention provides a video decoding method and apparatus using an adaptive parameter set.

[0043] A video decoding method and apparatus according to the present disclosure can obtain transform coefficients of a current block by decoding a bitstream, obtain inverse-quantized transform coefficients by performing inverse quantization on the obtained transform coefficients based on quantization-related parameters included in the bitstream, and reconstruct a residual block of the current block based on the inverse-quantized transform coefficients. Here, the quantization-related parameters can be obtained from an adaptive parameter set (APS) of the bitstream.

[0044] In the video decoding method and apparatus according to the present disclosure, obtaining the inverse quantized transform coefficients includes: obtaining an inverse quantization scaling list based on quantization-related parameters, obtaining a scaling factor based on the scaling list and a predetermined weight, and applying the obtained scaling factor to the transform coefficients.

[0045] In the video decoding method and apparatus according to the present disclosure, the quantization-related parameters may include at least one of a copy mode flag, a prediction mode flag, an increment identifier, or differential coefficient information.

[0046] In the video decoding method and apparatus according to the present disclosure, the weight may be obtained from a list of weight candidates predefined in the decoding apparatus.

[0047] In the video decoding method and apparatus according to the present disclosure, the number of the list of weight candidates predefined in the decoding apparatus is two or greater, and one of the weight candidate lists may be selectively used based on the coding parameters of the current block.

[0048] In the video decoding method and apparatus according to the present disclosure, an adaptive parameter set is a syntax structure including a set of parameters to be used in a predetermined picture unit, and the set of parameters includes at least one of adaptive loop filter (ALF)-related parameters, mapping model-related parameters of a shaper (luma mapping with chroma scaling), or quantization-related parameters.

[0049] In the video decoding method and apparatus according to the present disclosure, the adaptive parameter set may further include at least one of an identifier of the adaptive parameter set or adaptive parameter set type information.

[0050] In the video decoding method and apparatus according to the present disclosure, the same identifier is assigned to different adaptive parameter set types, and different lists may be used to manage the adaptive parameter sets for each type of adaptive parameter set.

[0051] The video encoding method and apparatus according to the present disclosure may obtain the transform coefficients of a current block, perform inverse quantization on the transform coefficients based on predetermined quantization-related parameters to obtain inverse quantized transform coefficients, and reconstruct a residual block of the current block based on the inverse quantized transform coefficients. Here, the quantization-related parameters may be transmitted in an adaptive parameter set (APS) of a bitstream.

[0052] A computer-readable recording medium stores a bitstream decoded by a video decoding method according to the present disclosure. The video decoding method includes: decoding the bitstream to obtain transform coefficients of a current block, obtaining inverse-quantized transform coefficients by performing inverse quantization on the obtained transform coefficients based on quantization-related parameters included in the bitstream, and reconstructing a residual block of the current block based on the inverse-quantized transform coefficients. Here, the quantization-related parameters can be obtained from an adaptive parameter set (APS) of the bitstream.

[0053] Embodiment of the invention

[0054] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings in this specification, so that those of ordinary skill in the art can easily implement the present disclosure. However, the present disclosure can be implemented in various different forms and is not limited to the embodiments described herein. In the drawings, parts not relevant to the description are omitted for clarity, and like reference numerals are attached to like parts throughout the specification.

[0055] Throughout this specification, when a part is described as being "connected" to another part, this includes not only the case of direct connection but also the case of being electrically connected to another element in the middle. Additionally, throughout the specification, when a part "includes" a component, this means that unless otherwise stated, other components may also be included rather than excluding other components.

[0056] As used throughout this specification, the term "step of (performing) ~" or "step of ~" does not mean "step for ~". Additionally, terms such as first and second may be used to describe various elements, but the elements should not be limited by these terms. These terms are only used for the purpose of distinguishing one component from another.

[0057] In addition, components shown in the embodiments of the present disclosure are independently shown to represent different characteristic functions, which does not mean that each component consists of a separate piece of hardware or a single software component unit. That is, for ease of description, each component unit is described by listing it as the corresponding component unit, and at least two of the component units are combined to form one component unit, or one component unit can be divided into multiple component units to perform functions. As long as the integrated implementation and the separate implementation of each of these components do not deviate from the essence of the present disclosure, the integrated implementation and the separate implementation of each of these components are also included within the scope of the present disclosure.

[0058] In various embodiments of the present disclosure described hereinafter, terms such as “~ unit,” “~ group,” “~ unit,” “~ module,” and “~ block” refer to a unit that processes at least one function or operation, and these units can be implemented in hardware or software or a combination of hardware and software.

[0059] In addition, a coding block refers to a processing unit of a set of target pixels for which encoding and decoding are currently performed, and can be used interchangeably as a coding block and a coding unit. In addition, a coding unit refers to a coding unit (CU), and can generally mean including a coding block (CB).

[0060] In addition, quadtree partitioning refers to dividing a block into four independent coding units, and binary tree partitioning refers to dividing a block into two independent coding units. In addition, ternary tree partitioning refers to dividing a block into three independent coding units at a ratio of 1:2:1.

[0061] Figure 1 is a block diagram showing an image encoding device according to the present disclosure.

[0062] Referring to Figure 1 , the video encoding device 100 may include: a picture partitioning module 110, prediction modules 120, 125, a transform module 130, a quantization module 135, a rearrangement module 160, an entropy encoding module 165, an inverse quantization module 140, an inverse transform module 145, a filter module 150, and a memory 155.

[0063] The picture partitioning module 110 may partition an input picture into one or more processing units. Herein, a processing unit may be a prediction unit (PU), a transform unit (TU), or a coding unit (CU). Hereinafter, in embodiments of the present disclosure, a coding unit may be used as a unit that performs encoding or a unit that performs decoding.

[0064] A prediction unit can be obtained by dividing a coding unit into at least one square or non-square of the same size, and the prediction units can be divided such that one prediction unit among the prediction units divided within a coding unit has a different shape and / or size from another prediction unit. When generating a prediction unit for performing intra prediction based on a coding unit and the coding unit is not the smallest coding unit, intra prediction can be performed without dividing the coding unit into a plurality of prediction units N×N.

[0065] The prediction modules 120 and 125 may include an inter prediction module 120 that performs inter prediction and an intra prediction module 125 that performs intra prediction. It may be determined whether to perform inter prediction or intra prediction for a prediction unit, and details according to each prediction method (e.g., intra prediction mode, motion vector, reference picture, etc.) may be determined. The residual value (residual block) between the generated prediction block and the original block may be input to the transform module 130. In addition, prediction mode information, motion vector information, etc. for prediction may be encoded together with the residual value by the entropy encoding module 165 and may be transmitted to the decoder. However, when applying the technique of deriving motion information from the decoder side according to the present disclosure, since the encoder does not generate prediction mode information and motion vector information, the corresponding information is not transmitted to the decoder. On the other hand, the encoder may signal and transmit information indicating that motion information is derived from the decoder side and used, as well as information about the technique for deriving motion information.

[0066] The inter prediction module 120 may perform prediction on a prediction unit based on information of at least one of a previous picture or a subsequent picture of the current picture, or in some cases may perform prediction on a prediction unit based on information of some encoded regions in the current picture. As inter prediction modes, various methods may be used, such as a merge mode, an advanced motion vector prediction (AMVP) mode, an affine mode, a current picture reference mode, and a combined prediction mode. In the merge mode, at least one motion vector among spatial / temporal merge candidates may be set as the motion vector of the current block, and inter prediction may be performed using the set motion vector. However, even in the merge mode, the preset motion vector may be corrected by adding an additional motion vector difference (MVD) to the preset motion vector. In this case, the corrected motion vector may be used as the final motion vector of the current block. The affine mode is a method of dividing the current block into predetermined sub-block units and performing inter prediction using the motion vectors obtained for each sub-block unit. Here, the sub-block unit is represented by N x M, and N and M may be integers of 4, 8, 16, or greater, respectively. The shape of the sub-block may be square or non-square. The sub-block unit may be a fixed unit pre-agreed upon for the encoding device, or may be variably determined by considering the size / shape of the current block, component type, etc. The current picture reference mode is an inter prediction method that uses a pre-reconstructed region and a predetermined block vector in the current picture to which the current block belongs, which will be referred to Figures 9 to 14A detailed description will be given. In the combined prediction mode, for a current block, a first prediction block is generated by inter-frame prediction and a second prediction block is generated by intra-frame prediction, and predetermined weights are applied to the first prediction block and the second prediction block to generate a final prediction block for the current block. Here, any one of the above inter-frame prediction modes can be used to perform inter-frame prediction. Intra-frame prediction can be performed using only the intra-frame prediction modes preset in the encoding device (for example, any one of the planar mode, DC mode, vertical / horizontal mode, and diagonal mode). Alternatively, an intra-frame prediction mode for intra-frame prediction can be obtained based on the intra-frame prediction modes of adjacent blocks (for example, at least one of left, top, top-left, top-right, and bottom-right) adjacent to the current block. In this case, the number of adjacent blocks to be used can be fixed at one or two, or can be three or more. Even when all of the above adjacent blocks are available, it is possible to limit the use to only one of the left adjacent block or the top adjacent block, or to limit the use to only the left adjacent block and the top adjacent block. The weights can be determined by considering whether the foregoing adjacent blocks are blocks encoded in the intra-frame mode. Assume that the weight w1 is applied to the first prediction block and the weight w2 is applied to the second prediction block. In this case, when both the left adjacent block / top adjacent block are blocks encoded in the intra-frame mode, w1 can be a natural number less than w2. For example, the ratio of w1 to w2 can be [1:3]. When neither the left adjacent block / top adjacent block is a block encoded in the intra-frame mode, w1 can be a natural number greater than w2. For example, the ratio of w1 to w2 can be [3:1]. When only one of the left adjacent block / top adjacent block is a block encoded in the intra-frame mode, w1 can be set to be the same as w2.

[0067] The inter-frame prediction module 120 may include a reference picture interpolation module, a motion prediction module, and a motion compensation module.

[0068] The reference picture interpolation module may receive reference picture information from the memory 155 and may generate pixel information about whole pixels or sub-pixels based on the reference picture. In the case of luminance pixels, an 8-tap DCT-based interpolation filter with different filter coefficients can be used to generate pixel information about whole pixels or sub-pixels in units of 1 / 4 pixels. In the case of chrominance signals, a 4-tap DCT-based interpolation filter with different filter coefficients can be used to generate pixel information about whole pixels or sub-pixels in units of 1 / 8 pixels.

[0069] The motion prediction module may perform motion prediction based on the reference pictures interpolated by the reference picture interpolation module. As methods for obtaining motion vectors, various methods may be used, such as a full search-based block matching algorithm (FBMA), three-step search (TSS), and new three-step search algorithm (NTS). The motion vector may have a motion vector value in units of 1 / 2 pixel or 1 / 4 pixel based on the interpolated pixels. The motion prediction module may perform prediction on a current prediction unit by using various motion prediction methods.

[0070] The intra prediction module 125 may generate a prediction unit based on reference pixel information which is pixel information in the current picture and adjacent to the current block. In a case where an adjacent block of the current prediction unit is a block on which inter prediction has been performed and the reference pixel is a pixel on which inter prediction has been performed, the reference pixel information of an adjacent block on which intra prediction has been performed may be used to replace the reference pixel included in the block on which inter prediction has been performed. In other words, when the reference pixel is unavailable, the information on the unavailable reference pixel may be replaced with at least one of the available reference pixels.

[0071] In addition, a residual block including residual information may be generated, where the residual information is a difference between a prediction unit on which prediction has been performed by the prediction modules 120 and 125 and the original block of the prediction unit. The generated residual block may be input to the transform module 130.

[0072] The transform module 130 may transform the residual block including the residual information between the original block and the prediction unit generated by the prediction modules 120 and 125 by using transform methods such as discrete cosine transform (DCT), discrete sine transform (DST), and KLT. Whether to apply DCT, DST, or KLT to transform the residual block may be determined based on the intra prediction mode information of the prediction unit used to generate the residual block.

[0073] The quantization module 135 may quantize the values transformed to the frequency domain by the transform module 130. The quantization coefficients may vary according to the blocks or importance of the picture. The values calculated by the quantization module 135 may be provided to the inverse quantization module 140 and the rearrangement module 160.

[0074] The rearrangement module 160 may rearrange the coefficient values for the quantized residual values.

[0075] The rearrangement module 160 may change coefficients in the form of a two-dimensional block into coefficients in the form of a one-dimensional vector by a coefficient scanning method. For example, the rearrangement module 160 may use a zigzag scanning method to scan from the DC coefficient to the coefficients in the high-frequency domain to change the coefficients into the form of a one-dimensional vector. Depending on the size of the transform unit and the intra prediction mode, a vertical scan that scans the coefficients in the form of a two-dimensional block in the column direction or a horizontal scan that scans the coefficients in the form of a two-dimensional block in the row direction may be used instead of the zigzag scan. In other words, it may be determined which scan method among the zigzag scan, the vertical scan, and the horizontal scan to use according to the size of the transform unit and the intra prediction mode.

[0076] The entropy coding module 165 may perform entropy coding based on the values calculated by the rearrangement module 160. The entropy coding may use various coding methods such as exponential Golomb, context-adaptive variable length coding (CAVLC), and context-adaptive binary arithmetic coding (CABAC). In this regard, the entropy coding module 165 may encode the residual value coefficient information of the decoding units from the rearrangement module 160 and the prediction modules 120, 125. In addition, according to the present disclosure, information indicating that motion information is obtained and used at the decoder side and information about the technique for obtaining the motion information may be signaled and transmitted.

[0077] The inverse quantization module 140 and the inverse transform module 145 may inverse-quantize the values quantized by the quantization module 135 and inverse-transform the values transformed by the transform module 130. The residual values generated by the inverse quantization module 140 and the inverse transform module 145 may be combined with the prediction units predicted by the motion prediction module, the motion compensation module, and the intra prediction module included in the prediction modules 120, 125 to generate a reconstructed block.

[0078] The filter module 150 may include at least one of a deblocking filter, an offset correction module, or an adaptive loop filter (ALF). The deblocking filter may remove block distortion that appears due to the boundaries between blocks in the reconstructed picture. The offset correction module may correct the offset with respect to the original image in units of pixels in the deblocked image. To perform offset correction on a specific picture, a method of applying an offset considering the edge information of each pixel may be used, or a method of dividing the pixels included in the image into a predetermined number of regions, determining the regions to which the offset is to be applied, and applying the offset to the determined regions may be used. The adaptive loop filter (ALF) may be performed based on the values obtained by comparing the filtered reconstructed image with the original image. After dividing the pixels included in the image into predetermined groups, one filter to be applied to the corresponding group may be determined, and filtering may be performed differently for each group.

[0079] The memory 155 may store the reconstructed blocks or pictures calculated by the filter module 150. When performing inter-frame prediction, the stored reconstructed blocks or pictures may be provided to the prediction modules 120 and 125.

[0080] Figure 2 is a block diagram showing an image decoding device according to the present disclosure.

[0081] Referring to Figure 2 , a device 200 for decoding video may include: an entropy decoding module 210, a rearrangement module 215, an inverse quantization module 220, an inverse transform module 225, prediction modules 230 and 235, a filter module 240, and a memory 245. [[ID=IO]]

[0082] When a video bitstream is input to the device for decoding video, the input bitstream may be decoded according to the inverse processing of the device for encoding video.

[0083] The entropy decoding module 210 may perform entropy decoding according to the inverse processing of the entropy encoding performed by the entropy encoding module of the video encoding device. For example, corresponding to the method performed by the video encoding device, various methods such as exponential Golomb, context-adaptive variable length coding (CAVLC), and context-adaptive binary arithmetic coding (CABAC) may be applied.

[0084] The entropy decoding module 210 may decode information regarding intra-frame prediction and inter-frame prediction performed by the encoding device.

[0085] The rearrangement module 215 may rearrange the bitstream entropy decoded by the entropy decoding module 210 based on the rearrangement method used in the encoding device. The rearrangement module may reconstruct and rearrange the coefficients in one-dimensional vector form into coefficients in two-dimensional block form. [[ID=ZT]]

[0086] The inverse quantization module 220 may perform inverse quantization based on the quantization parameter received from the encoding device and the rearranged coefficients of the block.

[0087] The inverse transform module 225 may perform an inverse transform on the quantization result generated by the device for encoding video, that is, the inverse DCT, inverse DST, and inverse KLT corresponding to the DCT, DST, and KLT performed by the transform module. The inverse transform may be performed based on the transmission unit determined by the video encoding device. In the inverse transform module 225 of the video decoding device, the transform scheme (e.g., DCT, DST, and KLT) may be selectively performed according to multiple pieces of information such as the prediction method, the size of the current block, and the prediction direction.

[0088] The prediction modules 230, 235 can generate a prediction block based on information about the generation of the prediction block received from the entropy decoding module 210 and information about previously decoded blocks or pictures received from the memory 245.

[0089] As described above, if the size of the prediction unit is the same as the size of the transform unit when performing intra prediction in the same manner as the operation of the video coding device, intra prediction can be performed on the prediction unit based on the pixels existing in the left, upper left, and top of the prediction unit. However, if the size of the prediction unit is different from the size of the transform unit when performing intra prediction, intra prediction can be performed using reference pixels based on the transform unit. Additionally, intra prediction using N x N partitioning can be used only for the smallest coding unit.

[0090] The prediction modules 230, 235 can include a prediction unit determination module, an inter prediction module, and an intra prediction module. The prediction unit determination module can receive various information such as prediction unit information, prediction mode information of the intra prediction method, and information about motion prediction of the inter prediction method from the entropy decoding module 210, can divide the current coding unit into prediction units, and can determine whether to perform inter prediction or intra prediction on the prediction units. On the other hand, if the encoder 100 does not transmit information related to motion prediction for inter prediction but transmits information indicating that motion information is derived from the decoder side and used and information about the technique for deriving the motion information, the prediction unit determination module determines the prediction performance of the inter prediction module 230 based on the information transmitted from the encoder 100.

[0091] The inter prediction module 230 can use the information required for inter prediction of the current prediction unit provided by the video coding device and perform inter prediction on the current prediction unit based on information of at least one of a previous picture or a subsequent picture of the current picture including the current prediction unit. To perform inter prediction, the inter prediction mode of the prediction unit included in the corresponding coding unit can be determined based on the coding unit. Regarding the inter prediction mode, the foregoing merge mode, AMVP mode, affine mode, current picture reference mode, combined prediction mode, etc. can be similarly used in the decoding device, and thus their detailed descriptions will be omitted herein. The inter prediction module 230 can determine the inter prediction mode of the current prediction unit with a predetermined priority.

[0092] The intra prediction module 235 can generate a prediction block based on pixel information in the current picture. When the prediction unit is a prediction unit that has undergone intra prediction, intra prediction can be performed based on the intra prediction mode information of the prediction unit received from the video encoding device. The intra prediction module 235 can include an Adaptive Intra Smoothing (AIS) filter, a reference pixel interpolation module, and a DC filter. The AIS filter filters the reference pixels of the current block, and can determine whether to apply the filter according to the prediction mode of the current prediction unit. AIS filtering can be performed on the reference pixels of the current block by using the prediction mode of the prediction unit and the AIS filter information received from the device for encoding the video. 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.

[0093] When the prediction mode of the prediction unit is a prediction unit that performs intra prediction based on the pixel values interpolated from the reference pixels, the reference pixel interpolation module can interpolate the reference pixels to generate reference pixels in units of pixels equal to or less than integer pixels. When the prediction mode of the current prediction unit is a prediction mode in which a prediction block is generated without interpolating the reference pixels, the reference pixels may not be interpolated. When the prediction mode of the current block is the DC mode, the DC filter can generate a prediction block by filtering.

[0094] The reconstructed block or picture can be provided to the filter module 240. The filter module 240 can include a deblocking filter, an offset correction module, and an ALF.

[0095] The deblocking filter of the video decoding device can receive information about the deblocking filter from the video encoding device, and can perform deblocking filtering on the corresponding block.

[0096] The offset correction module can perform offset correction on the reconstructed image based on the type of offset correction and the offset value information applied to the image during encoding. The ALF can be applied to the decoding unit based on the information about whether to apply the ALF, the ALF coefficient information, etc. received from the encoding device. The ALF information can be provided in a manner included in a specific parameter set.

[0097] The memory 245 can store the reconstructed picture or block to be used as a reference picture or block, and can provide the reconstructed picture to the output module.

[0098] The present disclosure relates to methods and devices for signaling various parameters applicable to each picture or slice in one parameter set, such as adaptive loop filters, shapers, quantization (scaling), and weighted prediction in video decoding techniques.

[0099] In addition, the present invention relates to methods and devices for managing parameter sets in a list form in a video decoder.

[0100] A parameter set predefined in an encoding / decoding device can be used to transmit parameters to be applied to a predetermined image unit. The image unit can be at least one of a video sequence, a picture, a slice, a tile, or a brick. For example, a predefined parameter set can be used to transmit parameters applicable to each picture or slice, such as an adaptive loop filter and a shaper. In this case, one parameter set is used, but additional signaling methods for the type of the parameter set can be used. Since one parameter set is used to signal different types, the parameter set identifier (ID) or the parameter set management list can be shared even if the types of the parameter sets are different. In the present disclosure, methods and apparatuses for sharing the parameter set identifier and list or independently managing them when transmitting various types of parameters using the same parameter set are proposed.

[0101] Figure 3 An embodiment of a syntax table of an adaptation parameter set (APS) is shown.

[0102] The adaptation parameter set globally defines / manages parameters for each APS type and is a parameter set for using / managing parameters by only signaling the identifier (ID) of the parameter set used in the corresponding image unit in the header of the corresponding image unit. That is, by using the adaptation parameter set, it is possible to omit defining various parameters applied to the above-mentioned predetermined image unit (e.g., one or more pictures, one or more slices) as separate parameter sets and signaling them on a per-image basis.

[0103] For example, various parameters applied to one or more pictures or one or more slices include filter parameters of an adaptive loop filter (ALF), mapping model-related parameters (LMCS: luma mapping with chroma scaling) of a shaper, etc.

[0104] In addition, it may also include weight-related parameters for weighted prediction and parameters for a block structure. Alternatively, it may also include picture (or slice, tile, etc.) partitioning-related parameters, reference picture set or reference structure-related parameters, quantization-related parameters, transform-related parameters, other in-loop filter-related parameters, etc. The quantization-related parameters and their APS types, the weight-related parameters and their APS types, the parameters of the block structure and their APS types, etc. will be described in detail in the present disclosure later.

[0105] As Figure 3As shown, according to an embodiment of the adaptive parameter set syntax table, the adaptation_parameter_set_id 301, which is an identifier of the adaptive parameter set, can be signaled.

[0106] Signaling the adaptive parameter set identifier 301 can mean assigning a unique specific value (number) to each of one or more adaptive parameter sets transmitted through a video stream. The adaptive parameter set identifier 301 can mean information for specifying any one of a plurality of adaptive parameter sets predefined in an encoding / decoding device.

[0107] In this case, the adaptive parameter set identifier can be represented as a value from 0 to 2 N -1, and bits with a fixed length of N bits can be used to transmit the adaptive parameter set identifier. In this case, according to an embodiment of the present disclosure, N can be one of 2, 3, 4, 5, and 6. In the Figure 3 syntax table shown, an embodiment where N is 3 is shown.

[0108] Despite having different adaptive parameter set types, the adaptive parameter set identifier 301 can use a single string of digits, independent of the adaptive parameter set type 302 described later.

[0109] Alternatively, in the case of different adaptive parameter set types, a separate string of digits can be used for each adaptive parameter set type. That is, the adaptive parameter set identifier 301 can be defined depending on the adaptive parameter set type 302.

[0110] In one embodiment, in the case of using an adaptive parameter set identifier 301 that depends on the adaptive parameter set type 302, the adaptive parameter set identifier 301 for the ALF adaptive parameter set type can have any value from 0 to 7. The adaptive parameter set identifier 301 for the LMCS adaptive parameter set type can have any value from 0 to 3. The adaptive parameter set identifier 301 for the quantization adaptive parameter set type can have any value from 0 to 7. In this case, parameter sets with different adaptive parameter set types 302 can use the same value. In one embodiment, the same value can be used for the adaptive parameter set identifier of ALF (ALF_APS_ID) and the adaptive parameter set identifier of LMCS (LMCS_APS_ID). Similarly, the same value can be used for the adaptive parameter set identifier of ALF (ALF_APS_ID) and the adaptive parameter set identifier of quantization (SCALING_APS_ID).

[0111] As Figure 3As shown, according to an embodiment of the APS grammar table, the aps_params_type 302 can be signaled, where the aps_params_type 302 is information about an APS type that specifies the type of parameters included in the corresponding APS.

[0112] As an APS type, an ALF APS type that indicates parameters of the ALF, an LMCS APS type that indicates parameters of the LMCS, etc. can be defined. As described above, a SCALING APS type that indicates quantization-related parameters can be additionally defined.

[0113] According to an embodiment of the present disclosure, the parameters included in the corresponding APS can vary depending on the APS type, and additional parameter-related syntax parsing processing for the corresponding APS type can be performed according to the APS type.

[0114] As Figure 3 shown, when the current APS type is ALF_APS, the ALF-related parameters can be parsed by calling alf_data() 303, and when the current APS type is LMCS_APS, lmcs_data() 304 can be called to parse the LMCS-related parameters. If the current APS type is SCALING_APS, the quantization-related parameters can be parsed by calling scaling_list_data().

[0115] Specifically, when the current APS type is ALF_APS, the ALF-related parameters can be extracted by calling the alf_data() function. The parameter extraction can be performed based on the above identifier 301. To this end, in the alf_data() function, the ALF-related parameters can be defined for each identifier 301, and the ALF-related parameters corresponding to the respective identifier 310 can be extracted. Alternatively, the parameter extraction can be performed without relying on the identifier 301 described above. Similarly, when the current APS type is LMCS_APS, the LMCS-related parameters can be extracted by calling the lmcs_data() function. In the lmcs_data() function, the LMCS-related parameters can be defined for each identifier 310. In this case, the LMCS-related parameters corresponding to the identifier 301 can be extracted. Alternatively, the parameter extraction can be performed without relying on the identifier 301 described above. If the current APS type is SCALING_APS, the quantization-related parameters can be extracted by calling the scaling_list_data() function. In the scaling_list_data() function, the quantization-related parameters can be defined for each identifier 310. In this case, the quantization-related parameters corresponding to the identifier 301 can be extracted. Alternatively, the parameter extraction can be performed without relying on the identifier 301 described above.

[0116] In addition, at least one of the ALF-related parameters, LMCS-related parameters, or quantization-related parameters can be extracted depending on the identifier 301, and the remaining parameters can be extracted without relying on the identifier 301. However, the present disclosure is not limited thereto, and all of the ALF-related parameters, LMCS-related parameters, and quantization-related parameters can be extracted depending on the identifier 301, or all of the ALF-related parameters, LMCS-related parameters, and quantization-related parameters can be extracted without relying on the identifier 301.

[0117] Whether to rely on the identifier 301 can be selectively determined according to the APS type. This selection can be pre-committed to the encoding / decoding device, or can be determined based on the value of the identifier 301 or whether it is activated. This can equally / apply similarly to various APS types described later.

[0118] In addition to this, APS types for weighted prediction, block structure, etc. can be defined. The implementation of the APS syntax table in which the APS types for weight prediction and block structure are defined will be described in detail later.

[0119] Figure 4 An implementation of the syntax table for transmitting and parsing quantization-related parameters is shown.

[0120] Reference Figure 4 , a copy mode flag (scaling_list_copy_mode_flag) may be signaled. The copy mode flag may indicate whether the scaling list is obtained based on the copy mode. For example, when the copy mode flag is a first value, the copy mode may be used, otherwise the copy mode may not be used. The copy mode flag may be parsed based on an identifier (id). Here, the identifier (id) is information derived based on the encoding parameters of the current block, which will be referred to later. Figure 5 Detailed description.

[0121] Reference Figure 4 A prediction mode flag (scaling_list_pred_mode_flag) may be signaled. The prediction mode flag may indicate whether the scaling list is obtained based on the prediction mode. For example, when the prediction mode flag is a first value, the prediction mode may be used, and otherwise, the prediction mode may not be used. The prediction mode flag may be parsed based on the copy mode flag. That is, the prediction mode flag may be parsed only when the copy mode is not used according to the copy mode flag.

[0122] Reference Figure 4 , a delta identifier (scaling_list_pred_id_delta) may be signaled. The delta identifier may be information for specifying a reference scaling list to be used to obtain a scaling list. The delta identifier may be signaled only in the case where the copy mode is used according to the aforementioned copy mode flag or the prediction mode is used according to the prediction mode flag. In addition, the delta identifier may be signaled by further considering the above-mentioned identifier (id), for example, Figure 4 As shown, the incremental identifier may be signaled only when the identifier (id) does not correspond to a value (0, 2, 8) predefined in the decoding device. In other words, when the maximum value of the width and height of the current block is 4 or 8, the component type of the current block is the luma component, and the prediction mode of the current block is the intra mode, the incremental identifier may not be signaled.

[0123] Reference Figure 4 , differential coefficient information (scaling_list_delta_coef) may be signaled. The differential coefficient information may refer to information encoded to specify the difference between the current coefficient and the previous coefficient of the scaling list. The differential coefficient information may be signaled only when the copy mode is not used according to the copy mode flag. That is, the differential coefficient information may be used in the prediction mode and the transmission mode, which will be described later.

[0124] Figure 5An embodiment of a method for reconstructing a residual block based on quantization-related parameters is shown.

[0125] Referring to Figure 5 , the bitstream can be decoded to obtain the transform coefficients S500 of the current block.

[0126] Here, the transform coefficients can mean the coefficients obtained by performing a transform and quantization on the residual samples in an encoding device. Alternatively, the transform coefficients can mean the coefficients obtained by skipping the transform of the residual samples and only performing quantization. The transform coefficients can be differently represented as coefficients, residual coefficients, transform coefficient levels, etc.

[0127] Referring to Figure 5 , the obtained transform coefficients can be inverse quantized to obtain the inverse quantized transform coefficients S510.

[0128] Specifically, the inverse quantized transform coefficients can be obtained by applying a predetermined scaling factor (hereinafter referred to as the final scaling factor) to the transform coefficients. Here, the final scaling factor can be obtained by applying a predetermined weight to the initial scaling factor.

[0129] The initial scaling factor can be determined based on a scaling list corresponding to an identifier of the current block (hereinafter referred to as the first identifier). The decoding device can obtain the first identifier based on the encoding parameters of the current block. The encoding parameters can include at least one of a prediction mode, a component type, a size, a shape, a transform type, or whether to skip the transform. The size of the current block can be represented as a width, a height, the sum of the width and the height, the product of the width and the height, or the maximum / minimum value of the width and the height. For example, the first identifier can be obtained as shown in Table 1.

[0130] [Table 1]

[0131]

[0132] Referring to Table 1, the first identifier can have any one of 0 to 27. The first identifier can be adaptively obtained according to the maximum value of the width (nTbW) and the height (nTbH) of the current block, the prediction mode (predMode), and the component type (cIdx).

[0133] The scaling list according to the present disclosure has the form of an M x N matrix, and M and N may be the same or different. Each component of the matrix may be referred to as a coefficient or a matrix coefficient. The size of the matrix may be variably determined based on a first identifier of a current block. Specifically, when the first identifier is less than a first threshold size, at least one of M and N may be determined to be 2, and when the first identifier is greater than or equal to the first threshold size and less than a second threshold size, at least one of M and N may be determined to be 4. When the first identifier is greater than the second threshold size, at least one of M and N may be determined to be 8. Here, the first threshold size may be an integer of 2, 3, 4, 5 or greater, and the second threshold size may be an integer of 8, 9, 10, 11 or greater.

[0134] The scaling list for inverse quantization of a current block may be derived based on quantization-related parameters. As Figure 4 shown, the quantization-related parameters may include at least one of a copy mode flag, a prediction mode flag, an increment identifier, or difference coefficient information.

[0135] The quantization-related parameters may be signaled in an Adaptive Parameter Set (APS). The Adaptive Parameter Set may refer to a syntax structure including parameters to be applied to a picture and / or a slice.

[0136] For example, one Adaptive Parameter Set may be signaled via a bitstream, and multiple Adaptive Parameter Sets may be signaled via the bitstream. Here, the multiple Adaptive Parameter Sets may be identified by an Adaptive Parameter Set identifier 301. Each Adaptive Parameter Set may have a different Adaptive Parameter Set identifier 301.

[0137] The quantization-related parameters of the scaling list for a current block may be signaled via an Adaptive Parameter Set specified by a predetermined identifier (hereinafter referred to as a second identifier) among the multiple Adaptive Parameter Sets. The second identifier is information encoded to specify any one of the multiple Adaptive Parameter Sets, and may be signaled in a predetermined image unit (picture, slice, tile, or patch). The second identifier is signaled in the header of the corresponding image unit, and the corresponding image unit may obtain the scaling list using the quantization-related parameters extracted from the Adaptive Parameter Set corresponding to the second identifier. Hereinafter, a method of obtaining the scaling list based on the quantization-related parameters will be described.

[0138] 1. In the case of the copy mode

[0139] In the copy mode, the scaling list of the current block can be set to be the same as the scaling list corresponding to the reference identifier (i.e., the reference scaling list). Here, the reference identifier can be derived based on the first identifier of the current block and a predetermined incremental identifier. The incremental identifier can be information encoded and signaled by the encoding device to identify the reference scaling list. For example, the reference identifier can be set to the difference between the first identifier of the current block and the incremental identifier.

[0140] However, in the case where the derived reference identifier is the same as the first identifier (i.e., the value of the incremental identifier is 0), the scaling list of the current block can be set to be the same as the default scaling list. The default scaling list is predefined in the decoding device, and each coefficient of the default scaling list can have a predetermined constant value (e.g., 2, 4, 8, 16).

[0141] The copy mode can be used based on a copy mode flag indicating whether to use the copy mode. For example, if the copy mode flag is a first value, the copy mode can be used; otherwise, the copy mode can be not used.

[0142] 2. In the case of the prediction mode

[0143] In the case of the prediction mode, the scaling list of the current block can be determined based on the prediction scaling list and the differential scaling list. Here, the prediction scaling list can be derived based on the aforementioned reference scaling list. That is, the reference scaling list specified by the first identifier and the incremental identifier of the current block can be set as the prediction scaling list. However, as described above, in the case where the derived reference identifier is the same as the first identifier (i.e., the value of the incremental identifier is 0), the prediction scaling list can be determined based on the default scaling list.

[0144] The differential scaling list also has the form of an M x N matrix, and each coefficient of the matrix can be derived based on the differential coefficient information signaled from the bitstream. For example, the differential coefficient information as the difference between the previous coefficient and the current coefficient can be signaled, and the current coefficient can be obtained using the signaled differential coefficient information and the previous coefficient. Through the above processing, at least one coefficient of the differential scaling list can be recovered. The scaling list of the current block can be determined by adding the prediction scaling list and the differential scaling list.

[0145] However, the prediction mode can be used based on a prediction mode flag indicating whether to use the prediction mode. For example, if the prediction mode flag is a first value, the prediction mode can be used; otherwise, the prediction mode can be not used.

[0146] 3. In the case of the transmission mode

[0147] At least one coefficient in the scaling list of the current block can be derived based on the differential coefficient information signaled by the encoding device. Here, the signaled differential coefficient information can be used to determine the differential coefficient that is the difference between the previous coefficient and the current coefficient. That is, the signaled differential coefficient information and the previous coefficient can be used to derive the current coefficient of the scaling list, and the scaling list of the current block can be obtained through this process.

[0148] In addition, a predetermined offset can be applied to at least one coefficient belonging to the obtained scaling list. Here, the offset can be a fixed constant value (e.g., 2, 4, 8, 16) pre-committed to the decoding device. For example, by adding the offset to at least one coefficient of the pre-obtained scaling list, the final scaling list for inverse quantization can be obtained.

[0149] However, the transmission mode can be used only when the foregoing copy mode and prediction mode are not used according to the copy mode flag and the prediction mode flag.

[0150] Meanwhile, the foregoing weight can be obtained from a weight candidate list predefined in the decoding device. The weight candidate list can include one or more weight candidates. Any one of the weight candidates belonging to the weight candidate list can be set as the weight.

[0151] For example, the weight candidate list can consist of six weight candidates. The weight candidate list can be defined as {forty, forty-five, fifty-one, fifty-seven, sixty-four, seventy-two} or {fifty-seven, sixty-four, seventy-two, eighty, ninety, one hundred and two}. However, the present disclosure is not limited thereto, and the number of weight candidates can be two, three, four, five, seven, or greater. Alternatively, the weight candidate list can include weight candidates with values less than forty or greater than one hundred and two.

[0152] The number of predefined weight candidate lists can be one, or two or greater. In the case where multiple weight candidate lists are defined, any one of the weight candidate lists can be selectively used. In this case, the selection can be performed by considering the encoding parameters of the current block. The encoding parameters are the same as those described above and will not be elaborated here.

[0153] For example, assume that a predefined list of weight candidates includes {40, 45, 51, 57, 64, 72} (hereinafter referred to as the first list) and {57, 64, 72, 80, 90, 102} (hereinafter referred to as the second list). If the current block is a block encoded by transform skip, the first list can be used; otherwise, the second list can be used. Alternatively, if the shape of the current block is square, the first list can be used; otherwise, the second list can be used. Alternatively, if the current block is a block encoded by transform skip, the first list is used. Otherwise, as described above, the first list or the second list can be selectively used according to the shape of the current block.

[0154] Referring Figure 5 , the residual block S520 of the current block can be reconstructed based on the inverse quantized transform coefficients.

[0155] In the case where transform skip is not applied, the residual block can be reconstructed by performing an inverse transform on the inverse quantized transform coefficients. On the other hand, in the case where transform skip is applied, the residual block can be reconstructed by setting the inverse quantized transform coefficients as residual samples.

[0156] The above reconstruction process of the residual block can be performed in the same / similar manner as in the encoding device, and will not be elaborated herein.

[0157] Figure 6 is a diagram showing an embodiment of an APS syntax table of the APS type for weight prediction added.

[0158] According to an embodiment of the present disclosure, parameters for weight prediction can be signaled and parsed using APS. In addition, an APS type for transmitting parameters for weight prediction can be defined, and it can be mapped to a number from 0 to 2 N -1. Here, N can be one of 2, 3, 4, and 5, and Figure 6 the embodiment shown in corresponds to the case where N is 3.

[0159] In the case where the type of the corresponding APS is a parameter type for weight prediction, the step 600 of signaling or parsing the parameters for weight prediction can be added.

[0160] When the current APS type is WP_APS, the relevant parameters for weight prediction can be extracted by calling the pred_weight_table() function. The pred_weight_table() function can define only the parameters related to unidirectional weight prediction, or can define only the parameters related to bidirectional weight prediction. Alternatively, the pred_weight_table() function can define the parameters related to unidirectional weight prediction and the parameters related to bidirectional weight prediction respectively. The pred_weight_table() function can define at least one of the parameters related to implicit weight prediction or the parameters related to explicit weight prediction.

[0161] Meanwhile, parameter extraction can be performed based on the above identifier 301. To this end, in the pred_weight_table() function, parameters related to weight prediction are defined for each identifier, and the parameters related to the weight prediction corresponding to the respective identifier 301 can be extracted. Alternatively, parameter extraction can be performed without relying on the identifier 301 described above.

[0162] Figure 7 It is a diagram showing another embodiment of the APS syntax table with an increased APS type for weight prediction.

[0163] According to an embodiment of the present disclosure, parameters for weight prediction can be signaled and parsed using APS. In addition, according to the direction of weight prediction, an APS type for transmitting parameters for unidirectional weight prediction can be defined, and an APS type for transmitting parameters for bidirectional weight prediction can be defined separately. Additionally, the APS type for unidirectional weight prediction and the APS type for bidirectional weight prediction can be mapped to a number from 0 to 2 N -1 respectively. Here, N can be one of 2, 3, 4, and 5, and Figure 7 the embodiment shown in corresponds to the case where N is 3.

[0164] When the type of the corresponding APS is one of the parameter types for weight prediction, the steps 700 or 701 of signaling or parsing the parameters for weight prediction can be added.

[0165] The pred_weight_table() function for unidirectional weight prediction and the bipred_weight_table() function for bidirectional weight prediction can be defined separately. When the current APS type is WP_APS, the pred_weight_table() function is called to extract parameters related to unidirectional weight prediction, while when the current APS type is WBP_APS, the bipred_weight_table() function is called to extract parameters related to bidirectional weight prediction. Parameter extraction can be performed based on the above identifier 301. To this end, pred_weight_table() and bipred_weight_table() can define parameters related to weight prediction for each identifier, and parameters related to weight prediction corresponding to the respective identifier 301 can be extracted. Alternatively, parameter extraction can be performed without relying on the identifier 301 described above.

[0166] Figure 8 FIG. is another embodiment of an APS syntax table showing an increased APS type for weight prediction.

[0167] As Figure 7 and Figure 8 shown, according to an embodiment of the present disclosure, parameters for weight prediction can be signaled and parsed using APS. Additionally, according to the direction of weight prediction, an APS type for transmitting parameters for unidirectional weight prediction can be defined, and an APS type for transmitting parameters for bidirectional weight prediction can also be defined separately. Additionally, the APS type for unidirectional weight prediction and the APS type for bidirectional weight prediction can be mapped to a number from 0 to 2 N -1 respectively. Here, N can be one of 2, 3, 4, and 5, and Figure 7 and Figure 8 the embodiments shown correspond to the case where N is 3.

[0168] When the type of the corresponding APS is one of the parameter types for weight prediction, the steps of signaling or parsing the parameters for weight prediction, step 800 or 801, can be added.

[0169] Additionally, in Figure 8 , the signaling or parsing steps can be performed by using the APS type for unidirectional prediction or bidirectional prediction as an input in the parameter signaling or parsing steps for weight prediction. The pred_weight_table() function can define parameters for unidirectional weight prediction and parameters for bidirectional weight prediction separately. Parameters for weight prediction corresponding to the aforementioned APS type 302 can be extracted. Alternatively, parameters for bidirectional weighted prediction can be derived from parameters for unidirectional weighted prediction.

[0170] Additionally, parameter extraction can be performed by considering the above identifier 301. To this end, pred_weight_table() can define weight prediction-related parameters for each identifier, and the weight prediction-related parameters corresponding to the respective identifier 301 can be extracted. Alternatively, parameter extraction can be performed without relying on the identifier 301 described above.

[0171] Figure 9 is a diagram showing an embodiment of a syntax table for transmitting and parsing parameters for weight prediction.

[0172] As shown Figure 8 In the diagram showing an embodiment of additional steps 800 and 801 for signaling or parsing parameters for weight prediction shown in, the aps_param_type corresponding to the APS type can be used as an input in the steps for signaling or parsing parameters for weight prediction.

[0173] Additionally, according to aps_param_type 901, in the case where aps_param_type means bidirectional prediction, an additional weighted prediction parameter signaling or parsing step 920 for bidirectional prediction can be added.

[0174] Additionally, when performing weight prediction using APS, the number of reference pictures (NumRefIdxActive), etc. can use a predefined fixed value or refer to parameters such as the reference picture structure transmitted in advance.

[0175] Figure 10 is a diagram showing an embodiment of an APS syntax table of the APS type for block partitioning structure with an increase.

[0176] Figure 10 is for showing in addition to Figure 3 and Figure 6 A diagram of an embodiment of a new APS type other than the APS syntax table shown in. In Figure 10 it is possible to signal or parse parameters applicable to the block partitioning structure of the above image unit using APS, and the parameters can be signaled by defining a separate parameter type for the block partitioning structure.

[0177] As mentioned above in the details of describing the present invention with respect to Figure 3 and Figure 6 It is possible to signal aps_params_type 302, which is information of the APS type regarding the type of parameters specified to be included in APS.

[0178] As the APS type, an ALF APS type that defines parameters indicating ALF, an LMCS APS type that defines parameters indicating LMCS, etc. can be defined.

[0179] In addition, according to an embodiment of the present disclosure, an APS type for transmitting parameters of a block partitioning structure can be defined, and parameter transmission and parsing for this APS type can be performed.

[0180] Furthermore, according to an embodiment of the present disclosure, the parameters included in the corresponding APS can vary depending on the APS type, and additional parameter-related syntax parsing processing for the corresponding APS type can be performed according to the APS type.

[0181] As Figure 10 shown, when the current APS type is an APS type for transmitting parameters of a block partitioning structure, step 1001 of signaling or parsing the parameters of the block partitioning structure can be additionally performed.

[0182] In addition, according to an embodiment of the present disclosure, parameters for weight prediction can be signaled and parsed using APS. Additionally, an APS type for transmitting parameters for weight prediction can be defined and mapped to a number from 0 to 2 N -1. Here, N can be one of 2, 3, 4, and 5, and Figure 10 the embodiment shown in

[0183] Figure 11 and Figure 12 show an embodiment of a syntax table of the parameters of the block structure that are additionally signaled or parsed when the current APS type is the parameters of the block partitioning structure.

[0184] Figure 11 shows an example of a syntax table in which, when a specific condition is satisfied, the parameters of the block partitioning structure applicable to an image unit are signaled together with the parameters 1110 of the luminance tree and the parameters 1120 of the chrominance tree in one parameter set.

[0185] On the other hand, Figure 12shows an embodiment in which, for both the luminance and chrominance trees, in the case where slice_log2_diff_min_qt_min_cb, slice_max_mtt_hierarchy_depth, and slice_max_mtt_hierachy_depth are not 0, information about a block partitioning structure is signaled using the syntax of slice_log2_diff_max_bt_min_qt and slice_log2_diff_max_tt_min_qt.

[0186] In the case of Figure 12 transmitting the block partitioning structure using APS, when signaling or parsing the block partitioning structure in the slice header, etc., one or more APSIDs for the parameters of the block partitioning structure can be signaled or parsed according to at least one of the type of the current slice or whether the chrominance separation tree (CST) technique is used. This embodiment is shown in Figure 13 below.

[0187] Figure 13 is a diagram showing a part of the syntax table for the slice header to show an embodiment of APS signaling or parsing for the block partitioning structure in the slice header.

[0188] As described in Figure 12 when transmitting the block partitioning structure using APS, one or more APSIDs for the parameters of the block partitioning structure can be signaled or parsed according to at least one of the type of the current slice or whether the chrominance separation tree (CST) technique is used when signaling or parsing the block partitioning structure in the slice header.

[0189] As Figure 13 shown, in the case where CST is not applied, that is, when the luminance tree and the chrominance tree are used identically, the block partitioning structure parameters corresponding to the APSID parsed in slice_mtt_aps_id 1300 are equally applicable to both the luminance tree and the chrominance tree.

[0190] On the other hand, in the case where CST is applied, that is, when the luminance tree and the chrominance tree are used differently, the block partitioning structure parameters corresponding to the APSID parsed in slice_mtt_aps_id 1300 are applied to the luminance tree, and the block partitioning structure parameters corresponding to the APSID parsed in slice_mtt_chroma_aps_id 1310 are applied to the chrominance tree.

[0191] Figure 13An embodiment of transmitting a block partitioning structure in a slice header is shown, but even in the case where the block partitioning structure is signaled or parsed in a sequence parameter set (SPS), a picture parameter set (PPS), etc., the block partitioning structure can be signaled or parsed in the same way as in the example of a slice.

[0192] Figure 14 FIG. is a diagram showing the concept of managing APS using different lists according to the APS type.

[0193] As described in the detailed description through Figure 3 In the case of different adaptive parameter set types depending on the adaptive parameter set type 302, the adaptive parameter set identifier 301 can be defined by using a separate digit string for each adaptive parameter set type.

[0194] In one embodiment, in the case of using the adaptive parameter set identifier 301 that depends on the adaptive parameter set type 302, the adaptive parameter set identifier 301 for the ALF adaptive parameter set type can have any value from 0 to 7. The adaptive parameter set identifier 301 for the LMCS adaptive parameter set type can have any value from 0 to 3. The adaptive parameter set identifier 301 for the quantization adaptive parameter set type can have any value from 0 to 7. In this case, parameter sets with different adaptive parameter set types 302 can use the same value. In one embodiment, the same value can be used for the adaptive parameter set identifier (ALF_APS_ID) of ALF and the adaptive parameter set identifier (LMCS_APS_ID) of LMCS. Similarly, the same value can be used for the adaptive parameter set identifier (ALF_APS_ID) of ALF and the adaptive parameter set identifier (SCALING_APS_ID) of quantization.

[0195] The same APS_ID is assigned to different APS types, and different lists can be used for each APS type for management. Assigning the same APS_ID means that the intervals of the identifier 301 values defined for each APS type can be the same as or overlap with each other. That is, as in the above example, the ALF_APS_ID and the SCALING_APS_ID can have any value from 0 to 7, and the LMCS_APS_ID can have any value from 0 to 3. In this case, even the same APS_ID can be assigned to different APS types. As Figure 14As shown, for each APS type, a list for ALF_APS, a list for LMCS_APS, a list for SCALING_APS, etc. are respectively defined / used, and one or more sets of adaptive parameters with different identifiers (APS_ID) can be defined in each list. Here, the list can be interpreted to mean a separate area or space.

[0196] Different APS_IDs can be assigned according to the APS type, and different lists can be used to manage the sets of adaptive parameters. Different APS_IDs can be assigned for each APS type and managed using one list. The same APS_ID can be assigned for different APS types, and the same list can be used to manage the APS types with the same APS_ID.

[0197] The various embodiments of the present disclosure are not listed as listing all possible combinations, but are intended to describe representative aspects of the present disclosure, and the content described in the various embodiments can be applied independently or in combinations of two or more.

[0198] In addition, the various embodiments of the present disclosure can be implemented by hardware, firmware, software, or a combination thereof. In the case of implementation by hardware, the various embodiments of the present disclosure can be implemented by one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), general purpose processors, controllers, microcontrollers, microprocessors, etc.

[0199] The scope of the present disclosure includes software or machine-executable instructions (e.g., operating systems, applications, firmware, programs, etc.) that allow the operations of the methods according to the various embodiments to be performed on a device or computer, and includes non-transitory computer-readable media that store and execute the software or instructions on the device or computer.

[0200] The present invention can also be implemented by the following embodiments.

[0201] Embodiment 1. A video decoding method, comprising:

[0202] Obtaining transform coefficients of a current block by decoding a bitstream;

[0203] Performing inverse quantization on the obtained transform coefficients based on quantization-related parameters included in the bitstream to obtain inverse-quantized transform coefficients; and

[0204] Reconstructing a residual block of the current block based on the inverse-quantized transform coefficients,

[0205] Among them, the quantization-related parameters can be obtained from the adaptive parameter set (APS) of the bitstream.

[0206] Embodiment 2. The method according to Embodiment 1, wherein obtaining the inverse-quantized transform coefficients includes:

[0207] Obtaining an inverse quantization scaling list based on the quantization-related parameters;

[0208] Deriving a scaling factor based on the scaling list and a predetermined weight; and

[0209] Applying the derived scaling factor to the transform coefficients.

[0210] Embodiment 3. The method according to Embodiment 2, wherein the quantization-related parameters can include at least one of a copy mode flag, a prediction mode flag, an increment identifier, or differential coefficient information.

[0211] Embodiment 4. The method according to Embodiment 2, wherein the weight is obtained from a list of weight candidates predefined in the decoding device.

[0212] Embodiment 5. The method according to Embodiment 4, wherein the number of the list of weight candidates predefined in the decoding device is two or greater than two, and

[0213] wherein one of the weight candidate lists is selectively used based on the coding parameters of the current block.

[0214] Embodiment 6. The method according to Embodiment 1, wherein the adaptive parameter set is a syntax structure including a set of parameters to be used in a predetermined image unit, and

[0215] wherein the set of parameters includes at least one of adaptive loop filter (ALF)-related parameters, mapping model-related parameters of a shaper (luminance mapping and chrominance scaling), or the quantization-related parameters.

[0216] Embodiment 7. The method according to Embodiment 6, wherein the adaptive parameter set further includes at least one of an identifier of the adaptive parameter set or adaptive parameter set type information.

[0217] Embodiment 8. The method according to Embodiment 7, wherein the same identifier is assigned to different adaptive parameter set types, and

[0218] wherein different lists are used to manage the adaptive parameter sets for each type of adaptive parameter set.

[0219] Embodiment 9. A video coding method, comprising:

[0220] Obtain the transform coefficients of the current block;

[0221] Perform inverse quantization on the transform coefficients based on predetermined quantization-related parameters to obtain inverse-quantized transform coefficients; and

[0222] Reconstruct the residual block of the current block based on the inverse-quantized transform coefficients,

[0223] wherein the quantization-related parameters are included in the adaptive parameter set (APS) of the bitstream and are transmitted in the adaptive parameter set (APS) of the bitstream.

[0224] Embodiment 10. A computer-readable recording medium storing a bitstream decoded by a video decoding method,

[0225] The video decoding method includes:

[0226] Decode the bitstream to obtain the transform coefficients of the current block;

[0227] Obtain inverse-quantized transform coefficients by performing inverse quantization on the obtained transform coefficients based on the quantization-related parameters included in the bitstream; and

[0228] Reconstruct the residual block of the current block based on the inverse-quantized transform coefficients,

[0229] wherein the quantization-related parameters are obtained from the adaptive parameter set (APS) of the bitstream.

[0230] Industrial applicability

[0231] The present disclosure can be used for encoding / decoding an image signal.

Claims

1. A video decoding method, comprising: generating a predicted block of a current block based on intra prediction or inter prediction; obtaining transform coefficients of the current block from a bitstream; obtaining inverse-quantized transform coefficients by performing inverse quantization on the transform coefficients based on quantization-related parameters included in the bitstream; generating a residual block of the current block by performing inverse transform on the inverse-quantized transform coefficients, and reconstructing the current block based on the predicted block and the residual block, wherein the quantization-related parameters are obtained from an adaptive parameter set (APS) of the bitstream, and wherein obtaining the inverse-quantized transform coefficients includes: obtaining a scaling list for the inverse quantization based on the quantization-related parameters; deriving a scaling factor based on the scaling list and a predetermined weight; and applying the scaling factor to the transform coefficients.

2. The method according to claim 1, wherein The quantization-related parameters can include at least one of a copy mode flag, a prediction mode flag, an increment identifier, or difference coefficient information.

3. The method according to claim 1, wherein The weight is obtained from a list of weight candidates predefined in a decoding device.

4. The method according to claim 3, wherein, The number of the list of weight candidates predefined in the decoding device is two or greater than two, and wherein one of the weight candidates lists is selectively used based on coding parameters of the current block.

5. The method according to claim 1, wherein, The adaptive parameter set is a syntax structure including a set of parameters to be used in a predetermined picture unit, and wherein the set of parameters includes at least one of adaptive loop filter (ALF)-related parameters, mapping model-related parameters of a shaper, or the quantization-related parameters.

6. The method according to claim 5, wherein The adaptive parameter set further includes at least one of an identifier of the adaptive parameter set or adaptive parameter set type information.

7. The method according to claim 6, wherein, The same identifier is assigned to different adaptive parameter set types, and wherein different lists are used to manage the adaptive parameter sets for each type of adaptive parameter set.

8. A video encoding method, comprising: generating a predicted block of a current block based on intra prediction or inter prediction; generating a residual block of the current block based on the predicted block; obtaining transform coefficients of the current block by performing transform on the residual block of the current block; performing quantization on the transform coefficients to obtain quantized transform coefficients; and encoding the quantized transform coefficients, wherein the quantization-related parameters of the current block are encoded in an adaptive parameter set (APS) of a bitstream, wherein performing the quantization on the transform coefficients includes: obtaining a scaling list for the quantization based on the quantization-related parameters; deriving a scaling factor based on the scaling list and a predetermined weight; and applying the scaling factor to the transform coefficients.

9. A method for transmitting a bitstream, comprising: generating a predicted block of a current block based on intra prediction or inter prediction; generating a residual block of the current block based on the predicted block; obtaining transform coefficients of the current block by performing transform on the residual block of the current block; performing quantization on the transform coefficients to obtain quantized transform coefficients; encoding the quantized transform coefficients to generate the bitstream; and transmitting the bitstream, Among them, the quantization-related parameters of the current block are encoded in the Adaptive Parameter Set (APS) of the bitstream. Among them, performing the quantization on the transform coefficients includes: obtaining a scaling list for the quantization based on the quantization-related parameters; deriving a scaling factor based on the scaling list and a predetermined weight; and applying the scaling factor to the transform coefficients.

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