Video signal processing method and device using block DPCM prediction method

Abstract

To provide a video signal processing method using a BlockDPCM prediction method, a video signal processor, and a recording media.SOLUTION: An operation of a video signal processing apparatus includes parsing BDPCM activation information indicating whether block-based delta pulse code modulation (BDPCM) is activated from a bitstream, parsing intra BDPCM information indicating whether BDPCM is applied to a current block when the BDPCM activation information indicates that BDPCM is activated, a width of the current block is equal to or smaller than a first value, and a height of the current block is equal to or smaller than a second value, parsing intra BDPCM direction information for the current block when the intra BDPCM information indicates that BDPCM is applied to the current block, and reconstructing the current block based on the intra BDPCM direction information.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present disclosure relates to a video signal processing method and apparatus, and more particularly to a video signal processing method and apparatus for encoding or decoding a video signal. [Background technology]

[0002] Compression coding refers to a series of signal processing techniques for transmitting digitized information over a communication line or storing it in a form suitable for a storage medium. Compression coding can be used to encode audio, video, text, and other data, but video compression is the technology that specifically targets video. Video signal compression is performed by removing redundant information by taking into account spatial correlation, temporal correlation, and stochastic correlation. However, with the recent development of various media and data transmission media, more efficient video signal processing methods and devices are needed. Summary of the Invention [Problem to be solved by the invention]

[0003] The present disclosure has the objective of increasing the coding efficiency of video signals. [Means for solving the problem]

[0004] A method for processing a video signal according to an embodiment of the present disclosure includes the steps of: parsing, from a bitstream, BDPCM activity information indicating whether Block-based Delta Pulse Code Modulation (BDPCM) is active; if the BDPCM activity information indicates BDPCM activation and the width of the current block is less than or equal to a first value and the height of the current block is less than or equal to a second value, parsing, from the bitstream, intra BDPCM information indicating whether BDPCM is applied to the current block; if the intra BDPCM information indicates that BDPCM is applied to the current block, parsing, from the bitstream, intra BDPCM direction information for the current block; and restoring the current block based on the intra BDPCM direction information.

[0005] The first value and the second value of the method for processing a video signal according to an embodiment of the present disclosure are characterized by being maximum block sizes that allow transform skipping.

[0006] In the method for processing a video signal according to an embodiment of the present disclosure, the intra-BDPCM information and the intra-BDPCM direction information are parsed for the luma component regardless of the chroma component.

[0007] In the method for processing a video signal according to an embodiment of the present disclosure, the BDPCM activity information is characterized by being signaled in a sequence.

[0008] In a method for processing a video signal according to one embodiment of the present disclosure, when intra BDPCM information indicates that BDPCM is to be applied to a current block, transform skip information of a transform block corresponding to the current block is not parsed from the bitstream, and if the value of the transform skip information is a first inferred value, the transform skip information indicates that transform is not to be applied to the block corresponding to the transform skip information.

[0009] A method for processing a video signal according to an embodiment of the present disclosure further includes the steps of: inferring the transform skip information to a first inferred value when the transform skip information is not present and the intra BDPCM information indicates that BDPCM is to be applied to the current block; and inferring the transform skip information to a second inferred value when the transform skip information is not present and the intra BDPCM information indicates that BDPCM is not to be applied to the current block.

[0010] In the method for processing a video signal according to an embodiment of the present disclosure, the intra BDPCM direction information indicates one of a horizontal direction or a vertical direction.

[0011] A method for processing a video signal according to one embodiment of the present disclosure is characterized by including a step of selecting an intra prediction mode corresponding to a horizontal direction from among a plurality of intra modes as the intra prediction mode of a current block when intra BDPCM direction information is 0, and a step of selecting an intra prediction mode corresponding to a vertical direction from among the plurality of intra modes as the intra prediction mode of the current block when the intra BDPCM direction information is 1.

[0012] In the method for processing a video signal according to an embodiment of the present disclosure, the intra prediction mode of a current block is used to determine the intra prediction modes of neighboring blocks that are reconstructed after the current block.

[0013] A video signal processing device according to an embodiment of the present disclosure includes a processor and a memory, and the processor parses BDPCM activity information indicating whether block-based delta pulse code modulation (BDPCM) is active from a bitstream based on instructions stored in the memory. If the BDPCM activity information indicates BDPCM activation, and if the width of a current block is less than or equal to a first value and the height of the current block is less than or equal to a second value, parses intra-BDPCM information indicating whether BDPCM is applied to the current block from the bitstream. If the intra-BDPCM information indicates that BDPCM is applied to the current block, parses intra-BDPCM direction information for the current block from the bitstream and restores the current block based on the intra-BDPCM direction information.

[0014] The first and second values ​​of the video signal processing device according to the embodiment of the present disclosure are maximum block sizes for which transform skipping is permitted.

[0015] Intra-BDPCM information and intra-BDPCM direction information of a video signal processing device according to an embodiment of the present disclosure are parsed for the luma component regardless of the chroma component.

[0016] The BDPCM activity information of the video signal processing device according to an embodiment of the present disclosure is signaled in a sequence.

[0017] When the intra BDPCM information of a video signal processing device according to one embodiment of the present disclosure indicates that BDPCM is to be applied to a current block, the transform skip information of the transform block corresponding to the current block is not parsed from the bitstream, and if the value of the transform skip information is a first inferred value, the transform skip information indicates that no transform is to be applied to the block corresponding to the transform skip information.

[0018] A processor of a video signal processing device according to one embodiment of the present disclosure infers, based on instructions stored in a memory, the transform skip information to a first inferred value if there is no transform skip information and the intra BDPCM information indicates that BDPCM is to be applied to the current block, and infers the transform skip information to a second inferred value if there is no transform skip information and the intra BDPCM information indicates that BDPCM is not to be applied to the current block.

[0019] The intra BDPCM direction information of the video signal processing device according to an embodiment of the present disclosure indicates one of the horizontal direction or the vertical direction.

[0020] A processor of a video signal processing device according to one embodiment of the present disclosure, based on an instruction stored in a memory, selects an intra prediction mode corresponding to the horizontal direction from among a plurality of intra modes as the intra prediction mode of a current block when the intra BDPCM direction information is 0, and selects an intra prediction mode corresponding to the vertical direction from among a plurality of intra modes as the intra prediction mode of a current block when the intra BDPCM direction information is 1.

[0021] The intra prediction mode of the video signal processing device according to an embodiment of the present disclosure is used to determine the intra prediction mode of the surrounding blocks that are reconstructed after the current block.

[0022] A method for processing a video signal according to an embodiment of the present disclosure includes the steps of: generating BDPCM activity information indicating whether block-based delta pulse code modulation (BDPCM) is active; generating intra-BDPCM information indicating whether BDPCM is applied to the current block if the BDPCM activity information indicates BDPCM activation and the width of the current block is less than or equal to a first value and the height of the current block is less than or equal to a second value; generating intra-BDPCM direction information for the current block if the intra-BDPCM information indicates that BDPCM is applied to the current block; and generating a bitstream based on the BDPCM activity information, the intra-BDPCM information, and the intra-BDPCM direction information.

[0023] In a method for processing a video signal according to an embodiment of the present disclosure, when intra BDPCM information indicates that BDPCM is applied to a current block, transform skip information of a transform block corresponding to the current block is not generated.

[0024] A video signal processing device according to an embodiment of the present disclosure includes a processor and a memory, and the processor generates BDPCM activity information indicating whether block-based delta pulse code modulation (BDPCM) is active, based on instructions stored in the memory. If the BDPCM activity information indicates BDPCM activation, and if the width of the current block is less than or equal to a first value and the height of the current block is less than or equal to a second value, generates intra-BDPCM information indicating whether BDPCM is applied to the current block. If the intra-BDPCM information indicates that BDPCM is applied to the current block, generates intra-BDPCM direction information for the current block, and generates a bitstream based on the BDPCM activity information, the intra-BDPCM information, and the intra-BDPCM direction information.

[0025] When the intra BDPCM information indicates that BDPCM is applied to the current block, the video signal processing apparatus according to the embodiment of the present disclosure does not generate transform skip information for the transform block corresponding to the current block.

[0026] A computer-readable recording medium having an encoded video signal recorded thereon according to an embodiment of the present disclosure includes the steps of: generating BDPCM activity information indicating whether block-based delta pulse code modulation (BDPCM) is active; generating intra-BDPCM information indicating whether BDPCM is applied to the current block if the BDPCM activity information indicates BDPCM activation and the width of the current block is less than or equal to a first value and the height of the current block is less than or equal to a second value; generating intra-BDPCM direction information for the current block if the intra-BDPCM information indicates that BDPCM is applied to the current block; and generating a bitstream based on the BDPCM activity information, the intra-BDPCM information, and the intra-BDPCM direction information. [Effects of the Invention]

[0027] According to embodiments of the present disclosure, video signal coding efficiency is increased. [Brief explanation of the drawings]

[0028] [Figure 1] 1 is a schematic block diagram of a video signal encoding apparatus according to an embodiment of the present invention; [Figure 2] 1 is a schematic block diagram of a video signal decoding device according to an embodiment of the present invention; [Figure 3] FIG. 1 illustrates an example of how coding tree units are divided into coding units within a picture. [Figure 4] FIG. 1 illustrates an embodiment of a method for signaling the splitting of quadtrees and multi-type trees. [Figure 5] 10A and 10B are diagrams illustrating an example of reference samples used to predict a current block in intra-prediction mode. [Figure 6] FIG. 10 is a diagram illustrating an example of a prediction mode used in intra prediction. [Figure 7]10 is a flowchart illustrating an operation of a video signal processing device according to an embodiment of the present disclosure. [Figure 8] FIG. 1 is a diagram showing prediction modes and quantized residual signals of Block DPCM (BDPCM). [Figure 9] FIG. 10 is a diagram showing BDPCM Bragg signals defined in a sequence parameter set. [Figure 10] A diagram showing a portion of a coding unit syntax structure. [Figure 11] FIG. 10 is a diagram showing a portion of coding unit syntax, including a size variable for a BDPCM application block. [Figure 12] A diagram showing a portion of a transform unit syntax structure. [Figure 13] FIG. 10 illustrates the signaling / parsing conditions for the transform skip flag within a portion of the transform unit syntax. [Figure 14] FIG. 10 is a diagram showing the relationship between a block to which BDPCM is applied and an intra-frame prediction mode variable. DETAILED DESCRIPTION OF THE INVENTION

[0029] The terms used in this specification are generally used as widely as possible while taking into consideration the functions of the present invention, but these may vary depending on the intentions of engineers in the field, customs, or the emergence of new technologies. In addition, in certain cases, the applicant may have arbitrarily selected terms, and in such cases, the meanings of these terms will be described in the relevant mode for carrying out the invention. Therefore, it is made clear that the terms used in this specification should be interpreted not simply as terms, but based on the substantive meanings of the terms and the overall content of this specification.

[0030] In this specification, some terms may be interpreted as follows: "Coding" may be interpreted as "Encoding" or "Decoding" in some cases. In this specification, an apparatus that encodes a video signal to generate a video signal bitstream is referred to as an encoding apparatus or encoder, and an apparatus that decodes a video signal bitstream to restore a video signal is referred to as a decoding apparatus or decoder. In this specification, "video signal processing apparatus" is used as a conceptual term that includes both an encoder and a decoder. "Information" is a term that includes values, parameters, coefficients, elements, etc., and may be interpreted differently in some cases, so the present invention is not limited thereto. "Unit" is used to refer to a basic unit of image processing or a specific position in a picture, and refers to an image area including both luma and chroma components. "Block" refers to an image area including specific components of luma and chroma components (i.e., Cb and Cr). However, depending on the embodiment, terms such as "unit," "block," "partition," and "area" may be used interchangeably. In this specification, the term "unit" or "block" refers to a coding unit (or coding block), a prediction unit (or prediction block), and a transform unit (or transform block). A "picture" refers to a field or a frame, and these terms may be used interchangeably depending on the embodiment.

[0031] 1 is a schematic block diagram of a video signal encoding apparatus 100 according to an embodiment of the present invention. Referring to FIG. 1, the encoding apparatus 100 of the present specification includes a transform unit 110, a quantization unit 115, an inverse quantization unit 120, an inverse transform unit 125, a filtering unit 130, a prediction unit 150, and an entropy coding unit 160.

[0032] The transform unit 110 transforms a residual signal, which is the difference between the input video signal and the prediction signal generated by the prediction unit 150, to obtain a transform coefficient value. For example, a discrete cosine transform (DCT), a discrete sine transform (DST), or a wavelet transform may be used. The discrete cosine transform and the discrete sine transform divide the input picture signal into blocks and then transform the block. During the transform, coding efficiency may vary depending on the distribution and characteristics of values ​​within the transform domain. The quantization unit 115 quantizes the transform coefficient values ​​output from the transform unit 110.

[0033] To improve coding efficiency, instead of directly coding the picture signal, the prediction unit 150 predicts a picture using a pre-coded region and adds the residual value between the original picture and the predicted picture to obtain a reconstructed picture. To avoid mismatch between the encoder and decoder, the encoder should use information available to the decoder when making predictions. To achieve this, the encoder performs a process of further reconstructing the coded current block. The inverse quantization unit 120 inversely quantizes the transform coefficient values, and the inverse transform unit 125 reconstructs the residual values ​​using the inversely quantized transform coefficient values. Meanwhile, the filtering unit 130 performs filtering operations to improve the quality of the reconstructed picture and the coding efficiency. For example, the filtering unit 130 may include a deblocking filter, a sample adaptive offset (SAO), an adaptive loop filter, etc. The filtered picture is stored in the decoded picture buffer (DPB) 156 for output or use as a reference picture.

[0034] The prediction unit 150 includes an intra prediction unit 152 and an inter prediction unit 154. The intra prediction unit 152 performs intra prediction within the current picture, and the inter prediction unit 154 performs inter prediction, predicting the current picture using a reference buffer stored in the decoded picture buffer 156. The intra prediction unit 152 performs intra prediction from reconstructed samples within the current picture and transmits intra coding information to the entropy coding unit 160. The intra coding information includes at least one of an intra prediction mode, a Most Probable Mode (MPM) flag, and an MPM index. The inter prediction unit 154 includes a motion estimation unit 154a and a motion compensation unit 154b. The motion estimation unit 154a obtains motion vector values ​​for the current region by referring to a specific region of the reconstructed reference signal picture. The motion estimation unit 154a transmits a motion information set (reference picture index, motion vector information) for the reference region to the entropy coding unit 160. The motion compensation unit 154b performs motion compensation using the motion vector values ​​received from the motion compensation unit 154a. The inter prediction unit 154 transmits inter coding information including motion information for the reference region to the entropy coding unit 160.

[0035] After the picture prediction is performed, the transform unit 110 converts residual values ​​between the original picture and the predicted picture to obtain transform coefficient values. The transform is performed in units of specific blocks within the picture, and the size of the specific blocks varies within a predetermined range. The quantization unit 115 quantizes the transform coefficient values ​​generated by the transform unit 110 and transmits the quantized values ​​to the entropy coding unit 160.

[0036] The entropy coding unit 160 generates a video signal bitstream by entropy coding the quantized transform coefficients, intra-coded information, and inter-coded information. The entropy coding unit 160 uses a variable length coding (VLC) scheme and an arithmetic coding scheme. The variable length coding (VLC) scheme converts input symbols into consecutive codewords, but the length of the codewords is variable. For example, frequently occurring symbols are represented by short codewords, and infrequently occurring symbols are represented by long codewords. Context-based adaptive variable length coding (CAVLC) is used as the variable length coding scheme. Arithmetic coding converts consecutive data symbols into a single prime number, and arithmetic coding obtains the optimal prime number bits required to represent each symbol. Context-based adaptive binary arithmetic coding (CABAC) is used as the arithmetic coding scheme.

[0037] The generated bitstream is encapsulated in Network Abstraction Layer (NAL) units as basic units. An NAL unit includes an integer number of coded coding tree units. In order for a video decoder to decode the bitstream, the bitstream must first be separated into NAL units and then each separated NAL unit must be decoded. Meanwhile, information required for decoding the video signal bitstream is transmitted via Raw Byte Sequence Payload (RBSP) of higher level sets such as a Picture Parameter Set (PPS), a Sequence Parameter Set (SPS), and a Video Parameter Set (VPS).

[0038] 1 illustrates an encoding device 100 according to one embodiment of the present invention, with separate blocks illustrating logically distinct elements of encoding device 100. Therefore, the elements of encoding device 100 described above may be implemented on a single chip or multiple chips depending on the device design. According to one embodiment, the operation of each element of encoding device 100 described above is performed by a processor (not shown).

[0039] 2 is a schematic block diagram of a video signal decoding apparatus 200 according to an embodiment of the present invention. Referring to FIG. 2, the decoding apparatus 200 of the present invention includes an entropy decoding unit 210, an inverse quantization unit 220, an inverse transform unit 225, a filtering unit 230, and a prediction unit 250.

[0040] The entropy decoding unit 210 entropy decodes the video signal bitstream to extract transform coefficient information, intra-coding information, inter-coding information, etc. for each region. The inverse quantization unit 220 inverse quantizes the quantized transform coefficients, and the inverse transform unit 225 restores residual values ​​using the inverse quantized transform coefficients. The video signal processing device 200 restores original pixel values ​​by combining the residual values ​​obtained from the inverse transform unit 225 with the predicted values ​​obtained from the prediction unit 250.

[0041] Meanwhile, the filtering unit 230 performs filtering on the picture to improve image quality. This includes a deblocking filter to reduce block distortion and / or an adaptive loop filter to remove distortion from the entire picture. The filtered picture is output or stored in the decoded picture buffer (DPB) 256 to be used as a reference picture for the next picture.

[0042] The prediction unit 250 includes an intra prediction unit 252 and an inter prediction unit 254. The prediction unit 250 generates a predicted picture using the coding type, transform coefficients for each region, intra / inter coding information, etc. decoded by the entropy decoding unit 210. To reconstruct the current block to be decoded, the current picture including the current block or a decoded region of another picture can be used. A picture (or tile / slice) that uses only the current picture for reconstruction, i.e., performs only intra prediction, is called an intra picture or I picture (or tile / slice), and a picture (or tile / slice) that performs both intra prediction and inter prediction is called an inter picture (or tile / slice). Among interpictures (or tiles / slices), a picture (or tile / slice) that uses at most one motion vector and reference picture index to predict sample values ​​for each block is called a predictive picture or P picture (or tile / slice), and a picture (or tile / slice) that uses at most two motion vectors and reference picture indexes is called a bi-predictive picture or B picture (or tile / slice). In other words, a P picture (or tile / slice) uses at most one motion information set to predict each block, and a B picture (or tile / slice) uses at most two motion information sets to predict each block. Here, a motion information set includes one or more motion vectors and one reference picture index.

[0043] The intra prediction unit 252 generates a predicted block using intra coding information and reconstructed samples in the current picture. As described above, the intra coding information includes at least one of an intra prediction mode, an MPM flag, and an MPM index. The intra prediction unit 252 predicts pixel values ​​of the current block using reconstructed pixels located to the left and / or above the current block as reference pixels. According to one embodiment, the reference pixels are pixels adjacent to the left boundary and / or the top boundary of the current block. According to another embodiment, the reference pixels are pixels of neighboring blocks of the current block that are adjacent to the left boundary of the current block within a predetermined distance from the left boundary of the current block and / or pixels adjacent to the top boundary of the current block within a predetermined distance from the top boundary of the current block. In this case, the neighboring blocks of the current block include at least one of a left (L) block, an upper (A) block, a below left (BL) block, an above right (AR) block, or an above left (AL) block adjacent to the current block.

[0044] The inter prediction unit 254 generates a prediction block using reference pictures and inter coding information stored in the decoded picture buffer 256. The inter coding information includes a motion information set (e.g., reference picture index, motion vector, etc.) of the current block relative to the reference block. Inter prediction includes L0 prediction, L1 prediction, and bi-prediction. L0 prediction is prediction using one reference picture included in the L0 picture list, and L1 prediction is prediction using one reference picture included in the L1 picture list. This requires one set of motion information (e.g., motion vector and reference picture index). The bi-prediction method uses up to two reference regions, and these two reference regions may exist in the same reference picture or in different pictures. That is, the bi-prediction method uses up to two sets of motion information (e.g., motion vector and reference picture index), and two motion vectors may correspond to the same reference picture index or different reference picture indexes. In this case, the reference picture is displayed (or output) either before or after the current picture in terms of time.

[0045] The inter prediction unit 254 obtains a current reference block using a motion vector and a reference picture index. The reference block exists in a reference picture corresponding to the reference picture index. Furthermore, pixel values ​​of a block identified by the motion vector or their interpolated values ​​are used as a predictor for the current block. For motion prediction with sub-pel pixel accuracy, for example, an 8-tab interpolation filter is used for the luma signal and a 4-tab interpolation filter is used for the chroma signal. However, the interpolation filters for sub-pel motion prediction are not limited thereto. In this way, the inter prediction unit 254 performs motion compensation, which predicts the texture of the current unit from a previously reconstructed picture using motion information.

[0046] A reconstructed video picture is generated by adding together the predicted value output from the intra prediction unit 252 or the inter prediction unit 254 and the residual value output from the inverse transform unit 225. That is, the video signal decoding apparatus 200 reconstructs a current block using the predicted block generated by the prediction unit 250 and the residual value obtained from the inverse transform unit 225.

[0047] 2 shows a decoding device 200 according to one embodiment of the present invention, with separate blocks logically separating elements of the decoding device 200. Thus, the elements of the decoding device 200 described above may be implemented on a single chip or multiple chips depending on the device design. According to one embodiment, the operation of each element of the decoding device 200 described above is performed by a processor (not shown).

[0048] FIG. 3 illustrates an embodiment in which a coding tree unit (CTU) is divided into coding units (CUs) within a picture. During video signal coding, a picture is divided into a sequence of coding tree units (CTUs). A coding tree unit consists of an NXN block of luma samples and two corresponding blocks of chroma samples. The coding tree unit is then divided into multiple coding units. A coding unit refers to a basic unit for processing a picture during the above-mentioned video signal processing, i.e., intra / inter prediction, transform, quantization, and / or entropy coding. Within a picture, the size and shape of coding units are not constant. Coding units have a square or rectangular shape. A rectangular coding unit (or rectangular block) includes a vertical coding unit (or vertical block) and a horizontal coding unit (or horizontal block). In this specification, a vertical block is a block whose height is greater than its width, and a horizontal block is a block whose width is greater than its height. Although a non-square block refers to a rectangular block in this specification, the present invention is not limited thereto. The encoding apparatus 100 and the decoding apparatus 200 have been described above. A video signal processing apparatus described below includes at least one of the encoding apparatus 100 and the decoding apparatus 200.

[0049] Referring to Figure 3, a coding tree unit is first divided into a quad tree (QT) structure. That is, in the quad tree structure, one node having a size of 2N x 2N is divided into four nodes having a size of N x N. In this specification, a quad tree is also referred to as a quaternary tree. The quad tree division is performed recursively, and all nodes do not need to be divided to the same depth.

[0050] Meanwhile, the leaf node of the above-mentioned quad tree is further divided into a multi-type tree (MTT) structure. According to an embodiment of the present invention, in the multi-type tree structure, one node is divided into a horizontally or vertically divided binary or ternary tree structure. That is, there are four division structures in the multi-type tree structure: vertical binary division, horizontal binary division, vertical ternary division, and horizontal ternary division. According to an embodiment of the present invention, in each of the tree structures, the width and height of the node are both powers of 2. For example, in a binary tree (BT) structure, a node of size 2N×2N is divided into two N×2N nodes by vertical binary division and into two 2N×N nodes by horizontal binary division. In addition, in a ternary tree (TT) structure, a node of size 2Nx2N is divided into (N / 2)x2N, Nx2N, and (N / 2)x2N nodes by vertical ternary division, and into 2Nx(N / 2), 2NxN, and 2Nx(N / 2) nodes by horizontal ternary division. Such multi-type tree division is performed recursively.

[0051] The leaf nodes of a multi-type tree can be coding units. If the coding unit is not excessively large compared to the maximum transform length, it is used as a unit of prediction and transform without further division. Meanwhile, in the above-mentioned quad trees and multi-type trees, at least one of the following parameters is predefined or transmitted via the RBSP of a higher-level set such as a PPS, SPS, or VPS: 1) CTU size: the size of the root node of the quad tree; 2) minimum QT size (MinQtSize): the size of the minimum QT leaf node allowed; 3) maximum BT size (MaxBtSize): the size of the maximum BT root node allowed; 4) maximum TT size (MaxTtSize): the size of the maximum TT root node allowed; 5) maximum MTT depth (MaxMttDepth): the maximum allowed depth of MTT division from the QT leaf node; 6) minimum BT size (MinBtSize): the size of the minimum BT leaf node allowed; 7) minimum TT size: the size of the minimum TT leaf node allowed.

[0052] 4 illustrates an embodiment of a method for signaling the splitting of a quadtree and a multi-type tree. Pre-set flags can be used to signal the splitting of the quadtree and multi-type tree. Referring to FIG. 4, at least one of a flag 'qt_split_flag' indicating whether to split a quadtree node, a flag 'mtt_split_flag' indicating whether to split a multi-type tree node, a flag 'mtt_split_vertical_flag' indicating the split direction of a multi-type tree node, and a flag 'mtt_split_binary_flag' indicating the split type of a multi-type tree node can be used.

[0053] According to an embodiment of the present invention, a coding tree unit is the root node of a quad tree and can be split into a quad tree structure first. In the quad tree structure, a 'qt_split_flag' is signaled for each node 'QT_node'. If the value of 'qt_split_flag' is 1, the corresponding node is split into four regular rectangular nodes, and if the value of 'qt_split_flag' is 0, the corresponding node becomes a leaf node 'QT_leaf_node' of the quad tree. Each quadtree leaf node 'QT_leaf_node' can be further split into a multi-type tree structure. In a multi-type tree structure, 'mtt_split_flag' is signaled for each node 'MTT_node'. If 'mtt_split_flag' is set to 1, the node is split into multiple rectangular nodes, and if 'mtt_split_flag' is set to 0, the node becomes a leaf node 'MTT_leaf_node' of the multi-type tree. If a multi-type tree node 'MTT_node' is split into multiple rectangular nodes (i.e., if 'mtt_split_flag' is set to 1), 'mtt_split_vertical_flag' and 'mtt_split_binary_flag' can be additionally signaled for the node 'MTT_node'. If the value of 'mtt_split_vertical_flag' is 1, vertical split of node 'MTT_node' is indicated, and if the value of 'mtt_split_vertical_flag' is 0, horizontal split of node 'MTT_node' is indicated. Also, if the value of 'mtt_split_binary_flag' is 1, node 'MTT_node' is split into two rectangular nodes, and if the value of 'mtt_split_binary_flag' is 0, node 'MTT_node' is split into three rectangular nodes.

[0054] 5 and 6 are diagrams illustrating in more detail an intra prediction method according to an embodiment of the present disclosure. As described above, the intra prediction unit predicts pixel values ​​of the current block using reconstructed pixels located to the left and / or above the current block as reference pixels.

[0055] First, FIG. 5 illustrates an example of reference samples used to predict a current block in intra prediction mode. According to one embodiment, the reference pixels are pixels adjacent to the left boundary and / or the top boundary of the current block. As shown in FIG. 5, if the size of the current block is W×H and pixels of a single reference line adjacent to the current block are used for intra prediction, the reference pixels are set using up to 2W+2H+1 adjacent pixels located to the left and / or top of the current block. Meanwhile, according to a further embodiment of the present disclosure, pixels of multiple reference lines are used for intra prediction of the current block. The multiple reference lines consist of n lines located within a predetermined range from the current block. According to one embodiment, if pixels of multiple reference lines are used for intra prediction, separate index information indicating the lines to be set as reference pixels is signaled. If at least some of the neighboring pixels used as reference pixels have not yet been restored, the intra prediction unit performs a reference sample padding process according to a predetermined rule to obtain the reference pixels. In addition, the intra prediction unit performs a reference sample filtering process to reduce intra prediction errors. That is, the reference pixels are obtained by filtering the neighboring pixels and / or the pixels obtained by the reference sample padding process, and the intra prediction unit predicts the pixels of the current block using the reference pixels obtained in this manner.

[0056] Next, Figure 6 illustrates an embodiment of prediction modes used in intra prediction. For intra prediction, intra prediction mode information indicating the intra prediction direction can be signaled. The intra prediction mode information indicates one of a plurality of intra prediction modes constituting an intra prediction mode set. If the current block is an intra predicted block, the decoder receives the intra prediction mode information of the current block from the bitstream. An intra prediction unit of the decoder performs intra prediction on the current block based on the extracted intra prediction mode information.

[0057] According to an embodiment of the present invention, the intra prediction mode set includes all intra prediction modes used in intra prediction (e.g., a total of 67 intra prediction modes). More specifically, the intra prediction mode set includes a planar mode, a DC mode, and a plurality of (e.g., 65) angle modes (i.e., directional modes). Each intra prediction mode is indicated by a predetermined index (i.e., intra prediction mode index). For example, as shown in FIG. 6, intra prediction mode index 0 indicates a planar mode, and intra prediction mode index 1 indicates a DC mode. In addition, intra prediction mode indexes 2 to 66 indicate different angle modes. Each angle mode indicates a different angle within a predetermined angle range. For example, the angle mode may indicate an angle within an angle range of 45° to −135° clockwise (i.e., a first angle range). The angle modes may be defined based on the 12 o'clock direction. In this case, intra prediction mode index 2 indicates horizontal diagonal (HDIA) mode, intra prediction mode index 18 indicates horizontal (HOR) mode, intra prediction mode index 34 indicates diagonal (DIA) mode, intra prediction mode index 50 indicates vertical (VER) mode, and intra prediction mode index 66 indicates vertical diagonal (VDIA) mode.

[0058] Meanwhile, the preset angle ranges are set differently depending on the shape of the current block. For example, if the current block is a rectangular block, a wide-angle mode specifying an angle greater than 45 degrees or less than -135 degrees clockwise is also used. If the current block is a horizontal block, the angle mode specifies an angle within an angle range between (45 + offset 1) degrees and (-135 + offset 1) degrees clockwise (i.e., a second angle range). In this case, angle modes 67 to 76 outside the first angle range are also used. If the current block is a vertical block, the angle mode specifies an angle within an angle range between (45 - offset 2) degrees and (-135 - offset 2) degrees clockwise (i.e., a third angle range). In this case, angle modes -10 to -1 outside the first angle range are also used. According to an embodiment of the present disclosure, the values ​​of offset 1 and offset 2 are determined differently depending on the ratio between the width and height of the rectangular block. Additionally, offset 1 and offset 2 are positive numbers.

[0059] According to a further embodiment of the present disclosure, the plurality of angle modes constituting the intra prediction mode set may include a base angle mode and an extended angle mode, wherein the extended angle mode is determined based on the base angle mode.

[0060] According to one embodiment, the basic angle mode is a mode corresponding to an angle used in intra prediction of the existing High Efficiency Video Coding (HEVC) standard, and the extended angle mode is a mode corresponding to an angle newly added in intra prediction of the next-generation video codec standard. More specifically, the basic angle mode is an angle mode corresponding to one of the intra prediction modes {2, 4, 6, ..., 66}, and the extended angle mode is an angle mode corresponding to one of the intra prediction modes {3, 5, 7, ..., 66}. That is, the extended angle mode is an angle mode between the basic angle modes within the first angle range. Therefore, the angle indicated by the extended angle mode is determined based on the angle indicated by the basic angle mode.

[0061] According to another embodiment, the base angle mode is a mode corresponding to an angle within a predetermined first angle range, and the extension angle mode is a wide angle mode outside the first angle range. That is, the base angle mode is an angle mode corresponding to one of the intra prediction modes {2, 3, 4, ..., 66}, and the extension angle mode is an angle mode corresponding to one of the intra prediction modes {-10, -9, ..., -1} and {67, 68, ..., 76}. The angle indicated by the extension angle mode is determined to be the angle opposite to the angle indicated by the corresponding base angle mode. Thus, the angle indicated by the extension angle mode is determined based on the angle indicated by the base angle mode. However, the number of extension angle modes is not limited thereto, and additional extension angles may be defined depending on the size and / or shape of the current block. For example, the extension angle mode may be defined as an angle mode corresponding to one of the intra prediction modes {-14, -13, ..., -1} and {67, 68, ..., 80}. Meanwhile, the total number of intra prediction modes included in the intra prediction mode set varies depending on the configuration of the base angle mode and the extended angle mode.

[0062] In the above embodiment, the spacing between extension angle modes is set based on the spacing between corresponding basic angle modes. For example, the spacing between extension angle modes {3, 5, 7, ..., 65} is determined based on the spacing between corresponding basic angle modes {2, 4, 6, ..., 66}. The spacing between extension angle modes {-10, -9, ..., -1} is determined based on the spacing between corresponding opposite basic angle modes {56, 57, ..., 65}, and the spacing between extension angle modes {67, 68, ..., 76} is determined based on the spacing between corresponding opposite basic angle modes {3, 4, ..., 12}. The angular spacing between extension angle modes is set to be the same as the angular spacing between corresponding basic angle modes. The number of extension angle modes in the intra prediction mode set is set to be less than or equal to the number of basic angle modes.

[0063] According to an embodiment of the present disclosure, an extended angle mode is signaled based on a base angle mode. For example, a wide angle mode (i.e., an extended angle mode) replaces at least one angle mode (i.e., a base angle mode) within a first angle range. The replaced base angle mode is an angle mode corresponding to the opposite side of the wide angle mode. That is, the replaced base angle mode is an angle mode corresponding to an angle opposite to the angle indicated by the wide angle mode, or an angle that is offset from the opposite angle by a preset offset index. According to an embodiment of the present disclosure, the preset offset index is 1. An intra-prediction mode index corresponding to the replaced base angle mode is further mapped to a wide angle mode to signal the corresponding wide angle mode. For example, wide angle modes {-10, -9, ..., -1} are signaled by intra-prediction mode indexes {57, 58, ..., 66}, respectively, and wide angle modes {67, 68, ..., 76} are signaled by intra-prediction mode indexes {2, 3, ..., 11}, respectively. In this way, by using the intra prediction mode index for the base angular mode to signal the extension angular mode, even if the configurations of the angular modes used for intra prediction of each block are different, the same set of intra prediction mode indexes is used to signal the intra prediction mode, thereby minimizing signaling overhead due to changes in the intra prediction mode configuration.

[0064] Meanwhile, whether or not to use the extended angle mode is determined based on at least one of the shape and size of the current block. According to one embodiment, if the size of the current block is larger than a preset size, the extended angle mode is used for intra prediction of the current block, and if not, only the base angle mode is used for intra prediction of the current block. According to another embodiment, if the current block is a non-square block, the extended angle mode is used for intra prediction of the current block, and if the current block is a square block, only the base angle mode is used for intra prediction of the current block.

[0065] The intra prediction unit determines reference pixels and / or interpolated reference pixels to be used for intra prediction of the current block based on intra prediction mode information of the current block. If the intra prediction mode index indicates a specific angle mode, reference pixels or interpolated reference pixels corresponding to the specific angle from the current pixel of the current block are used to predict the current pixel. Therefore, different sets of reference pixels and / or interpolated reference pixels are used for intra prediction depending on the intra prediction mode. After intra prediction of the current block is performed using the reference pixels and intra prediction mode information, the decoder restores pixel values ​​of the current block by adding the residual signal of the current block obtained from the inverse transform unit to the intra predicted value of the current block.

[0066] FIG. 7 is a flowchart showing the operation of a video signal processing device according to an embodiment of the present disclosure.

[0067] Each step in FIG. 7 will be described in detail with reference to FIGS.

[0068] FIG. 8 is a diagram illustrating prediction modes and quantized residual signals of Block DPCM (BDPCM) according to one embodiment of the present disclosure.

[0069] Block-based delta pulse code modulation (BDPCM) is an intra-frame (intra) prediction method. BDPCM uses two intra-frame (intra) prediction modes. Among the common intra-frame prediction modes, vertical and horizontal prediction modes are used. When a total of 67 intra-frame prediction modes are used, the vertical prediction mode index is 50 and the horizontal prediction mode index is 18. When BDPCM is used, one of the two modes is signaled. When BDPCM is applied to the current coding block, unfiltered samples are used as reference samples. When vertical prediction mode is applied to BDPCM, samples corresponding to the width of the current coding block can be used, and each sample predicts the same value for the corresponding column. When horizontal prediction mode is applied to BDPCM, samples corresponding to the height of the current coding block can be used, and each sample predicts the same value for all samples in the corresponding row. Blocks to which BDPCM is applied skip the transformation process and are coded into residual signals that are notified to the decoder. "A. BDPCM prediction mode" in FIG. 8 is a method related to residual signal coding.

[0070]

number

[0071]

number

[0072] The decoder performs the reverse calculation of the encoder to generate a quantized residual signal, which is added to the predicted value to create a reconstructed signal.

[0073] FIG. 9 is a diagram showing BDPCM flags defined in a sequence parameter set.

[0074] A BDPCM flag is defined at a higher level to turn on / off the corresponding function. Arranged from the higher level, it is divided into video parameter set, sequence parameter set, picture parameter set, etc. In the present disclosure, the flag is defined as a sequence parameter set (SPS). However, this is not limited to this. BDPCM activation information (sps_bdpcm_enabled_flag) indicates whether BDPCM is activated. The video signal processing device performs step 710 of parsing the BDPCM activation information (sps_bdpcm_enabled_flag) from the bitstream. If the BDPCM activation information (sps_bdpcm_enabled_flag) is 1, it indicates that BDPCM is activated. If the value is 0, it indicates that BDPCM is deactivated. The indicative value may be defined inversely, and activation and deactivation may be indicated in any form.

[0075] As already described, in FIG. 9, the BDPCM activation information (sps_bdpcm_enabled_flag) is defined on a sequence basis, but is not limited to this. The BDPCM activation information (sps_bdpcm_enabled_flag) is signaled on at least one basis of a Coding Tree Unit (CTU), slice, tile, tile group, picture, subpicture, sequence, or video. If the BDPCM activation information (sps_bdpcm_enabled_flag) is signaled on a Coding Tree Unit (CTU), slice, tile, tile group, picture, subpicture, or video basis, the name of the BDPCM activation information (sps_bdpcm_enabled_flag) may be different. However, its function remains the same.

[0076] Referring to FIG. 9, the BDPCM enablement information (sps_bdpcm_enabled_flag) is parsed from the bitstream without any additional conditions. However, this is not limited to this. The video signal processing device parses the transform skip enablement information (sps_transform_skip_enabled_flag) from the bitstream, which indicates whether the transform skip information (transform_skip_flag) exists in the transform unit. The transform unit is a unit for transforming pixels included in a coding block and is included in the coding block. The current transform unit is included in the current block. The transform skip enablement information (sps_transform_skip_enabled_flag) indicates whether the transform skip is enabled or disabled. The transform skip enablement information (sps_transform_skip_enabled_flag) is signaled on a sequence-by-sequence basis. If the transform skip activation information (sps_transform_skip_enabled_flag) is 1, it indicates that the transform skip information (transform_skip_flag) is present, and the video signal processing device will later parse the transform skip information (transform_skip_flag) from the bitstream. If the transform skip activation information (sps_transform_skip_enabled_flag) is 0, it indicates that the transform skip information (transform_skip_flag) is not present, and the video signal processing device will not later parse the transform skip information (transform_skip_flag) from the bitstream. The fact that a decoder in the video signal processing device does not parse the transform skip information indicates that an encoder in the video signal processing device does not generate the transform skip information. According to the present disclosure, if the transform skip activation information (sps_transform_skip_enabled_flag) is 1, the video signal processing device parses the BDPCM activation information (sps_bdpcm_enabled_flag) from the bitstream.

[0077] FIG. 10 is a diagram illustrating a portion of a coding unit syntax structure.

[0078] Figure 10 shows the structure of information required for each coding block to be predicted. The encoder signals the information according to the corresponding conditions, and the decoder also parses and acquires the information from the bitstream according to the corresponding conditions. If pcm_flag[x0][y0] at the upper left coordinate (x0, y0) of the coding block is 0, indicating that PCM mode is not applied, the video signal processor checks whether treeType is SINGLE_TREE or DUAL_TREE_LUMA. If treeType is SINGLE_TREE or DUAL_TREE_LUMA, the video signal processor parses intra BDPCM information (intra_bdpcm_flag) from the bitstream. The intra BDPCM information (intra_bdpcm_flag) indicates whether BDPCM is applied to the current block. If intra BDPCM information (intra_bdpcm_flag) is 1, it means that BDPCM is applied to the current block. Furthermore, if the intra BDPCM information (intra_bdpcm_flag) is 0, it means that BDPCM is not applied to the current block. However, this is not limited thereto. If the intra BDPCM information (intra_bdpcm_flag) is 0, it means that BDPCM is applied to the current block, and if the intra BDPCM information (intra_bdpcm_flag) is 1, it means that BDPCM is not applied to the current block.

[0079] The intra BDPCM information (intra_bdpcm_flag) is expressed in the format of intra_bdpcm_flag[x0][y0], where x0 and y0 are the coordinates of the current block. More specifically, x0 and y0 are the coordinates of the upper left pixel of the current block.

[0080] For the intra BDPCM information (intra_bdpcm_flag) to be parsed, it must satisfy the width and height conditions of the corresponding coding unit and the activation / deactivation condition of the BDPCM enablement information (sps_bdpcm_enabled_flag). For example, the width and height must both be 32 or less, and the BDPCM enablement information (sps_bdpcm_enabled_flag) must be set to 1, indicating activation. If the intra BDPCM information (intra_bdpcm_flag[x0][y0]) is set to 1, indicating migration, the intra BDPCM direction information (intra_bdpcm_dir_flag[x0][y0]) is signaled / parsed. This flag indicates the prediction mode applied to the BDPCM. The prediction mode is one of 18 horizontal prediction modes and 50 directional prediction modes. If the value of the intra BDPCM direction information (intra_bdpcm_dir_flag[x0][y0]) is 0, it indicates intra prediction mode 18, and if it is 1, it indicates intra prediction mode 50. Whether or not the BDPCM function is used in a coding block is determined by the value of sps_bdpcm_enabled_flag defined at a higher level.

[0081] FIG. 11 is a diagram showing a part of the coding unit syntax, including a size variable of a BDPCM-applied block.

[0082] The size of the block to which BDPCM is applied may be variably changed according to a preset variable, or may be applied together with other preset variables. If the BDPCM enablement information (sps_bdpcm_enabled_flag) indicates that BDPCM is enabled, and the width of the current block is equal to or smaller than a first value (Value 1), and the height of the current block is equal to or smaller than a second value (Value 2), the video signal processing device performs step 720 of parsing intra BDPCM information (intra_bdpcm_flag), which indicates whether BDPCM is applied to the current block, from the bitstream.

[0083] More specifically, the condition for signaling / parsing intra BDPCM information (intra_bdpcm_flag[x0][y0]) is when the coding block width (cbWidth) is smaller than or equal to a first value (Value 1), and the coding block height (cbHeight) is smaller than or equal to a second value (Value 2). Value 1 and Value 2 may be the same or different from each other. For example, the first value (Value 1) and the second value (Value 2) are the maximum block size (MaxTsSize) applied to transform skip. The maximum block size (MaxTsSize) applied to transform skip is the maximum block size allowing transform skip. The maximum block size (MaxTsSize) allowing transform skip is a value between 4 and 32. The maximum block size (MaxTsSize) allowing transform skip is defined as follows: The syntax variable log2_transform_skip_max_size_minus2 specifies the maximum block size for which transform skip is applied, and its value is between 0 and 3. If the variable (log2_transform_skip_max_size_minus2) does not exist, it is inferred to be 0. Using the variable (log2_transform_skip_max_size_minus2), the maximum block size (MaxTsSize) for which transform skipping is allowed is set as 1<<(log2_transform_skip_max_size_minus2+2).

[0084] Alternatively, a separate block size variable for BDPCM may be set without using log2_transform_skip_max_size_minus2 for the transform skip condition. For example, the variable MaxBdpcmSize is used. The size of MaxBdpcmSize is set based on the value signaled by log2_bdpcm_max_size_minus2. MaxBdpcmSize is set as 1 << (log2_transform_skip_max_size_minus2 + 2). log2_transform_skip_max_size_minus2 has a maximum value of 0, and its maximum values ​​are one of 7, 6, 5, 4, 3, 2, and 1. When log2_transform_skip_max_size_minus2 for the transform skip condition is used, there is no need to set an additional variable, and there may be no additional information transmitted from the encoder to the decoder. If you use log2_transform_skip_max_size_minus2 instead, you will need an additional variable like log2_bdpcm_max_size_minus2, but it will give you more flexibility in the block. You can also set Value 1 and Value 2 differently in a similar way to the above.

[0085] The video signal processing device includes sps_bdpcm_enabled_flag in the signaling / parsing conditions of intra BDPCM information (intra_bdpcm_flag), such that sps_bdpcm_enabled_flag && cbWidth <= Value 1 && cbHeight <= Value 2.

[0086] 11 shows the structure of information required for each coding block to be predicted, where the encoder signals the information according to the corresponding conditions, and the decoder also parses and acquires the information from the bitstream according to the corresponding conditions. Referring to line 1110, the video signal processing device determines whether pcm_flag[x0][y0] indicates that PCM mode is not applied at the coordinates (x0, y0) of the upper left corner of the coding block. Referring to line 1120, if pcm_flag[x0][y0] is equal to 0, which indicates that PCM mode is not applied, at the coordinates (x0, y0) of the upper left corner of the coding block, the video signal processing device can determine whether treeType is SINGLE_TREE or DUAL_TREE_LUMA. Furthermore, if treeType is SINGLE_TREE or DUAL_TREE_LUMA, the video signal processing device determines whether the BDPCM activation information (sps_bdpcm_enabled_flag) indicates BDPCM activation, whether the width of the current block is equal to or smaller than a first value (Value 1), or whether the height of the current block is equal to or smaller than a second value (Value 2). Although line 1130 does not describe whether the BDPCM activation information (sps_bdpcm_enabled_flag) indicates BDPCM activation, it also determines whether the BDPCM activation information (sps_bdpcm_enabled_flag) indicates BDPCM activation. Here, the first and second values ​​are the maximum block size (MaxTsSize) that allows transform skipping. The maximum block size (MaxTsSize) that allows transform skipping has already been described, so a repeated description will be omitted.

[0087] Referring to line 1140, the video signal processing device performs step 720 of parsing intra BDPCM information (intra_bdpcm_flag) from the bitstream if the BDPCM activation information (sps_bdpcm_enabled_flag) indicates BDPCM activation, the width of the current block is less than or equal to a first value, and the height of the current block is less than or equal to a second value.

[0088] The intra BDPCM information (intra_bdpcm_flag) indicates whether BDPCM is applied to the current block. The intra BDPCM information (intra_bdpcm_flag) is expressed in the format intra_bdpcm_flag[x0][y0], where x0 and y0 are the coordinates of the current block. More specifically, x0 and y0 are the coordinates of the upper left pixel of the current block.

[0089] Referring to line 1150, the video signal processing apparatus determines whether the intra BDPCM information (intra_bdpcm_flag[x0][y0]) indicates the use of BDPCM. Referring to line 1160, if the intra BDPCM information (intra_bdpcm_flag) indicates that BDPCM is applied to the current block, it performs step 730 of parsing the intra BDPCM direction information (intra_bdpcm_dir_flag) for the current block from the bitstream. The intra BDPCM direction information (intra_bdpcm_dir_flag) indicates either the horizontal or vertical direction. For example, if the intra BDPCM direction information (intra_bdpcm_dir_flag) is 0, it indicates the horizontal direction. Also, if the intra BDPCM direction information (intra_bdpcm_dir_flag) is 1, it indicates the vertical direction. However, the present invention is not limited to this. If the intra BDPCM direction information (intra_bdpcm_dir_flag) is 1, it indicates horizontal mode, and if the intra BDPCM direction information (intra_bdpcm_dir_flag) is 0, it indicates vertical mode.

[0090] The intra BDPCM direction information (intra_bdpcm_dir_flag) indicates the prediction mode applied to the BDPCM. The prediction mode is either intra prediction mode 18 or intra prediction mode 50. Intra prediction mode 18 is a horizontal prediction mode, and intra prediction mode 50 is a vertical prediction mode. If the value of the intra BDPCM direction information (intra_bdpcm_dir_flag[x0][y0]) is 0, the BDPCM prediction method is horizontal. If the value of the intra BDPCM direction information (intra_bdpcm_dir_flag[x0][y0]) is 1, the BDPCM prediction direction is vertical. If the value of the intra BDPCM direction information (intra_bdpcm_dir_flag[x0][y0]) is 0, it indicates intra prediction mode 18, and if it is 1, it indicates intra prediction mode 50. The value of the BDPCM enablement information (sps_bdpcm_enabled_flag) defined at a higher level determines whether or not a corresponding function is used in a coding block.

[0091] The intra BDPCM information (intra_bdpcm_flag) and the intra BDPCM direction information (intra_bdpcm_dir_flag) are parsed separately for the chroma and luma components. The intra BDPCM information (intra_bdpcm_flag) and the intra BDPCM direction information (intra_bdpcm_dir_flag) are parsed for the luma component regardless of the chroma component. That is, the video signal processing device parses the intra BDPCM information (intra_bdpcm_luma_flag) for the luma component or the intra BDPCM direction information (intra_bdpcm_luma_dir_flag) for the luma component in the same manner as described above, and parses the intra BDPCM information (intra_bdpcm_chroma_flag) for the chroma component or the intra BDPCM direction information (intra_bdpcm_chroma_dir_flag) for the chroma component in a similar manner. The process of obtaining intra BDPCM information for the luma component (intra_bdpcm_luma_flag) and intra BDPCM direction information for the luma component (intra_bdpcm_luma_dir_flag) is slightly different from the process of obtaining intra BDPCM information for the chroma component (intra_bdpcm_chroma_flag) and intra BDPCM direction information for the chroma component (intra_bdpcm_chroma_dir_flag). This is because the current block of the luma component and the current block of the chroma component may be different from each other. More specifically, the size or position of the current block of the luma component may be different from the size or position of the current block of the chroma component. The video signal processing device parses intra BDPCM information for the luma component (intra_bdpcm_luma_flag) from the bitstream if the BDPCM activation information (sps_bdpcm_enabled_flag) indicates BDPCM activation, the width of the current luma coding block is less than or equal to a first value, and the height of the current luma coding block is less than or equal to a second value. Similarly, the video signal processing device parses intra BDPCM information for the chroma component (intra_bdpcm_chroma_flag) from the bitstream if the BDPCM activation information (sps_bdpcm_enabled_flag) indicates BDPCM activation, the width of the current chroma coding block is less than or equal to the first value, and the height of the current chroma coding block is less than or equal to a second value. Also, if the intra BDPCM information for the luma component (intra_bdpcm_luma_flag) indicates that BDPCM is applied to the current luma coding block, the luma intra BDPCM direction information (intra_bdpcm_luma_dir_flag) for the current luma coding block is parsed from the bitstream.Similarly, if the intra BDPCM information for the chroma component (intra_bdpcm_chroma_flag) indicates that BDPCM is applied to the current chroma coding block, the chroma intra BDPCM direction information (intra_bdpcm_chroma_dir_flag) for the current chroma coding block is parsed from the bitstream, where the first and second values ​​are the maximum block size (MaxTsSize) that allows transform skipping.

[0092] In the present disclosure, intra BDPCM information (intra_bdpcm_flag) includes intra BDPCM information for the luma component (intra_bdpcm_luma_flag) and intra BDPCM information for the chroma component (intra_bdpcm_chroma_flag). Also, in the present disclosure, intra BDPCM direction information (intra_bdpcm_dir_flag) includes intra BDPCM direction information for the luma component (intra_bdpcm_luma_dir_flag) and intra BDPCM direction information for the chroma component (intra_bdpcm_chroma_dir_flag).

[0093] The video signal processing apparatus performs step 740 of restoring the current block based on the intra BDPCM direction information (intra_bdpcm_dir_flag). Step 740 of restoring the current block based on the intra BDPCM direction information (intra_bdpcm_dir_flag) has been described with reference to FIG. 8, so a duplicate description will be omitted.

[0094] FIG. 12 is a diagram showing a part of the transform unit syntax.

[0095] For a coding block to which BDPCM is applied, the residual signal is coded in the manner described in FIG. 8 without a transform process. The syntax variable for preventing a corresponding block from undergoing a transform process is the transform skip information (transform_skip_flag). That is, the transform skip information (transform_skip_flag) indicates whether or not a transform is to be applied to the corresponding block. Alternatively, if the transform skip information (transform_skip_flag) is equal to a pre-specified value, the transform skip information (transform_skip_flag) indicates that a transform is not to be applied to the current block. If the transform skip information (transform_skip_flag) is 1, a transform is skipped for the corresponding transform block. Also, if the transform skip information (transform_skip_flag) is 0, a transform is not skipped for the corresponding transform block. However, this is not limiting, and if the transform skip information (transform_skip_flag) is 0, a transform may be skipped for the corresponding transform block. Also, if the transform skip information (transform_skip_flag) is 1, a transform may not be skipped for the corresponding transform block.

[0096] The transform skip information (transform_skip_flag) is expressed for each color component in the format of transform_skip_flag[x0][y0]. Here, x0 and y0 are the coordinates of the corresponding transform block. More specifically, x0 and y0 are the coordinates of the upper left pixel of the corresponding block. As already explained, the current block includes at least one transform block. The encoder performs transform in units of transform blocks, and the decoder performs inverse transform in units of transform blocks.

[0097] The conditions for signaling / parsing transform skip information (transform_skip_flag[x0][y0]) must be satisfied, first, whether the value of tu_cbf_luma[x0][y0] is 1, whether treeType is different from DUAL_TYPE_TREE_CHROMA, whether the width and height of the coding unit are equal to or smaller than 32, whether IntraSubPartitionsSplit[x0][y0] is equal to ISP_NO_SPLIT, whether cu_sbt_flag is 0, and whether intra BDPCM information (intra_bdpcm_flag[x0][y0]) is 0. The following condition must also be satisfied: transform_skip_enabled_flag && tbWidth <= MaxTsSize && tbHeight <= MaxTsSize. tbWidth is a variable indicating the width of the transform block, and tbHeight is a variable indicating the height of the transform block.

[0098] The above conditions are merely examples, and some of the conditions may be replaced with other conditions or deleted. Furthermore, other conditions may be added. However, some of the conditions may be maintained to improve the efficiency of video encoding or decoding. For example, as described above, because a transform skip is applied to a coding block to which BDPCM is applied, the application of the transform skip is determined by inference without signaling / parsing additional information. That is, if the intra BDPCM information (intra_bdpcm_flag) indicates that BDPCM is applied to the current block, the transform skip information (transform_skip_flag), which indicates whether a transform is applied to the current block, is not parsed. As described above, if the intra BDPCM information (intra_bdpcm_flag) is 1, it indicates that BDPCM is applied to the current block. If the intra BDPCM information (intra_bdpcm_flag) indicates that BDPCM is not applied to the current block, the video signal processing device further determines at least one of the above-mentioned conditions to determine whether to parse the transform skip information (transform_skip_flag).

[0099] If some of the above conditions are not met, the transform skip information (transform_skip_flag) is not parsed, which may result in a case where the transform skip information (transform_skip_flag[x0][y0]) does not exist. For example, if the intra BDPCM information (intra_bdpcm_flag) indicates that BDPCM is to be applied to the current block, the transform skip information (transform_skip_flag[x0][y0]) does not exist. The video signal processing device infers the transform_skip_flag based on the intra BDPCM information (intra_bdpcm_flag) and determines whether or not to apply the transform skip.

[0100] For example, if there is no transform skip information (transform_skip_flag[x0][y0]) and the intra BDPCM information (intra_bdpcm_flag[x0][y0]) is 1, the video signal processing apparatus infers the transform skip information (transform_skip_flag[x0][y0]) as a first inference value. Here, the intra BDPCM information (intra_bdpcm_flag) being 1 indicates that BDPCM is applied to the current block. If the value of the transform skip information is the first inference value, it indicates that no transform is applied to the block corresponding to the transform skip information.

[0101] Furthermore, if there is no transform skip information (transform_skip_flag[x0][y0]) and the intra BDPCM information (intra_bdpcm_flag[x0][y0]) is 0, the video signal processing apparatus infers the transform skip information (transform_skip_flag[x0][y0]) as a second inference value. Here, the intra BDPCM information (intra_bdpcm_flag) being 0 indicates that BDPCM is not applied to the current block. If the value of the transform skip information is the second inference value, it indicates that transformation is applied to the block corresponding to the transform skip information. Here, the first inference value is 1 and the second inference value is 0. However, the present invention is not limited to this, and the first inference value may be 0 and the second inference value may be 1.

[0102] If the transform skip information (transform_skip_flag[x0][y0]) of the block to which BDPCM is applied is 1, the residual_ts_coding() function is called. This function codes the residual signal transformed in Figure 8. In addition, the MinBdpcmSize condition for tbWidth and tbHeight is also added in the same way. The corresponding values ​​are signaled and calculated in a similar way at higher levels. The MinBdpcmSize condition may also be added and applied to the conditions shown in Figure 13.

[0103] FIG. 13 illustrates the signaling / parsing conditions for the transform skip flag within a portion of the transform unit syntax.

[0104] Figure 13 is an embodiment similar to Figure 12. Since transform skip is applied to coding blocks to which BDPCM is applied, the application of transform skip is determined by inference without signaling / parsing additional information. Therefore, a condition indicating that BDPCM is not applied is added to the conditions for signaling / parsing the transform skip flag.

[0105] As shown in Figure 13, the video signal processing device uses a condition such as (transform_skip_enabled_flag && tbWidth <= MaxTsSize && tbHeight <= MaxTsSize && (! intra_bdpcm_flag[x0][y0])) as a condition for parsing the transform skip information (transform_skip_flag). Also, the video signal processing device parses the transform skip information (transform_skip_flag) if transform_skip_enabled_flag is 1, tbWidth <= MaxTsSize is satisfied, tbHeight <= MaxTsSize is satisfied, and intra_bdpcm_flag[x0][y0] is 0. In other words, transform_skip_flag[x0][y0] is signaled / parsed only for blocks to which the transform skip condition and BDPCM are not applied.

[0106] The conditions for signaling / parsing the transform skip information (transform_skip_flag[x0][y0]) are as follows: Referring to line 1310, the video signal processing device checks whether the value of tu_cbf_luma[x0][y0] is 1, whether the treeType is different from DUAL_TYPE_TREE_CHROMA, whether the width (tbWidth) and height (tbHeight) of the transform block are equal to or less than 32, whether IntraSubPartitionsSplit[x0][y0] is equal to ISP_NO_SPLIT, whether cu_sbt_flag is 0, and whether the intra BDPCM information (intra_bdpcm_flag[x0][y0]) is 0. As already explained, if the intra BDPCM information (intra_bdpcm_flag) is 0, it means that BDPCM is not applied to the current block. Also, referring to line 1320, the video signal processor determines whether the condition transform_skip_enabled_flag&&tbWidth<=MaxTsSize&&tbHeight<=MaxTsSize is met.

[0107] The above conditions are merely examples, and some of the conditions may be replaced with other conditions or deleted. Furthermore, other conditions may be added. However, some of the conditions may be maintained to improve the efficiency of video encoding or decoding. For example, as described above, a coding block to which BDPCM is applied is subject to transform skip, and therefore no additional information is signaled / parsed. That is, if the intra BDPCM information (intra_bdpcm_flag) indicates that BDPCM is applied to the current block, the transform skip information (transform_skip_flag), which indicates whether a transform is applied to the current block, is not parsed. As described above, if the intra BDPCM information (intra_bdpcm_flag) is 1, this indicates that BDPCM is applied to the current block. If the intra BDPCM information (intra_bdpcm_flag) indicates that BDPCM is not applied to the current block, the video signal processing device further evaluates at least one of the above conditions to determine whether to parse the transform skip information (transform_skip_flag).

[0108] If at least one of the above conditions is not satisfied, the transform skip information (transform_skip_flag[x0][y0]) may not exist. For example, if the intra BDPCM information (intra_bdpcm_flag) indicates that BDPCM is to be applied to the current block, the transform skip information (transform_skip_flag[x0][y0]) does not exist. The video signal processing device infers the transform_skip_flag based on the intra BDPCM information (intra_bdpcm_flag) to determine whether the transform skip is applicable. For example, if the transform skip information (transform_skip_flag[x0][y0]) does not exist and the intra BDPCM information (intra_bdpcm_flag[x0][y0]) is 1, the video signal processing device infers the transform skip information (transform_skip_flag[x0][y0]) to 1. Here, intra BDPCM information (intra_bdpcm_flag) set to 1 indicates that BDPCM is applied to the current block. Conversely, if there is no transform skip information (transform_skip_flag[x0][y0]) and the intra BDPCM information (intra_bdpcm_flag[x0][y0]) is 0, the video signal processing device infers the transform skip information (transform_skip_flag[x0][y0]) to 0. Here, intra BDPCM information (intra_bdpcm_flag) set to 0 indicates that BDPCM is not applied to the current block. In this way, the encoder does not transmit redundant information and the decoder does not perform parsing, thereby improving encoding / decoding efficiency. Since the encoder does not generate transform_skip_flag, encoding efficiency is improved and bitstream size is reduced. Furthermore, the decoder infers information without a parsing process, improving computing efficiency.

[0109] The transform skip information (transform_skip_flag) is parsed separately for the chroma component and the luma component. The chroma component includes Cb and Cr. The transform skip information (transform_skip_flag) is parsed separately for Cb and Cr. The transform skip information (transform_skip_flag) may be parsed for the luma component regardless of the chroma component. The transform skip information (transform_skip_flag) may be parsed for the chroma component regardless of the luma component. The video signal processing device acquires the transform skip information (transform_skip_flag) for the luma component and acquires the transform skip information (transform_skip_flag) for the chroma component. Also, if there is no transform skip information (transform_skip_flag), the transform skip information (transform_skip_flag) is inferred separately for the chroma component and the luma component. The video signal processing device infers the transform skip information (transform_skip_flag) using the method already described. Alternatively, the video signal processing apparatus may use the transform skip information (transform_skip_flag) for the luma component to infer the transform skip information (transform_skip_flag) for the chroma component.

[0110] FIG. 14 is a diagram showing the relationship between a block to which BDPCM is applied and an intra-frame prediction mode variable.

[0111] A block to which BDPCM is applied indicates an intra (intra-picture) prediction mode according to the value of intra_bdpcm_dir_flag[x0][y0]. For example, if the intra BDPCM direction information (intra_bdpcm_dir_flag) is 0, the video signal processing device selects an intra prediction mode (mode 18) corresponding to the horizontal direction from among multiple intra modes as the intra prediction mode of the current block. Also, if the intra BDPCM direction information (intra_bdpcm_dir_flag) is 1, the video signal processing device selects an intra prediction mode (mode 50) corresponding to the vertical direction from among multiple intra modes as the intra prediction mode of the current block.

[0112] Since the intra prediction mode used in a block to which BDPCM is applied is the same as the general intra prediction mode, the corresponding mode is stored as a variable (IntraPredModeY[xCb][yCb]) indicating the intra prediction mode of the current predicted block and used to derive the MPM of the general coding block. That is, the intra prediction mode of the current block is used to determine the intra prediction mode of the surrounding block to be reconstructed after the current block. In addition, the video signal processing device stores the intra prediction mode of the current block as a candidate for determining the intra prediction mode of the surrounding block to be reconstructed after the current block. The video signal processing device selects one of the stored candidates based on the parsed information to determine the intra prediction mode of the surrounding block to be reconstructed after the current block.

[0113] In addition, the intra prediction mode of the already reconstructed coding block is used to determine the intra prediction mode of the current block. The video signal processing device stores the intra prediction modes of the already reconstructed coding block as candidates for determining the intra prediction mode of the current block. The video signal processing device selects one of the stored candidates based on the parsed information to determine the intra prediction mode of the current block.

[0114] For example, if the current block is a general block to which BDPCM is not applied, one of the neighboring blocks that has already been reconstructed is a block to which BDPCM is applied, and intra_bdpcm_dir_flag[x0][y0] is 0, IntraPredModeY[xCb][yCb] stores the 18th intra prediction mode. The video signal processing device uses the 18th intra prediction mode of the neighboring block that has already been reconstructed to encode or decode the general coding block. More specifically, the video signal processing device uses the 18th intra prediction mode of the neighboring block that has already been reconstructed when inducing MPM for the current block. The prediction mode of the block to which BDPCM is applied aims to minimize the final residual signal, so the prediction method may be the same. However, since the residual pattern may differ from general situations, a preset value is used. The DC mode is set to the horizontal mode of BDPCM in the vertical direction, the vertical mode of BDPCM in the horizontal direction, or one of the two directions in BDPCM.

[0115] Although the above description has been made from the perspective of a decoder, the same operation is performed in an encoder. In the above description, the term "parsing" has been described with emphasis on the process of obtaining information from a bitstream, but from the perspective of an encoder, it can be interpreted as configuring corresponding information in a bitstream. Therefore, the term "parsing" is not limited to the operation of a decoder, but can also be interpreted as the act of configuring a bitstream in an encoder.

[0116] The above-described embodiments of the present invention may be implemented in various ways, for example, in hardware, firmware, software, or a combination thereof.

[0117] In the case of a hardware implementation, the method according to an embodiment of the present invention may be implemented by one or more ASICs (Application Specific Integrated Circuits), DSPs (Digital Signal Processors), DSDPs (Digital Signal Processing Devices), PDLs (Programmable Logic Devices), FPGAs (Field Programmable Gate Arrays), processors, controllers, microcontrollers, microprocessors, etc.

[0118] In the case of implementation by firmware or software, the methods according to the embodiments of the present invention may be implemented in the form of modules, procedures, or functions that perform the functions or operations described above. The software code is stored in a memory and executed by a processor. The memory may be located inside or outside the processor and exchange data with the processor through various means known in the art.

[0119] The above description of the present invention is for illustrative purposes only, and those skilled in the art will understand that the present invention can be easily modified into other specific forms without changing the technical spirit or essential features of the present invention. Therefore, it should be understood that the above-described embodiments are illustrative in all respects and are not limiting. For example, each component described as a single component may be implemented in a distributed form, and components described as distributed may also be implemented in a combined form.

[0120] The above-described preferred embodiments of the present invention have been disclosed for illustrative purposes, and those skilled in the art will be able to improve, modify, substitute or add to various other embodiments within the technical spirit and scope of the present invention as disclosed in the appended claims.

Claims

1. 1. A method of processing a video signal for decoding, comprising: Parsing BDPCM activation information indicating whether block-based delta pulse code modulation (BDPCM) is activated from the bitstream; parsing intra-BDPCM information indicating whether BDPCM is applied to the current block from the bitstream if the BDPCM activation information indicates activation of BDPCM, the width of the current block is less than or equal to a first value, and the height of the current block is less than or equal to a second value; parsing intra BDPCM direction information for the current block from a bitstream if the intra BDPCM information indicates that BDPCM is applied to the current block; reconstructing the current block based on the intra BDPCM direction information; 1. A method for processing a video signal, comprising:

2. 2. The method of claim 1, wherein the first value and the second value are maximum block sizes that allow transform skipping.

3. 2. The method of claim 1, wherein the intra BDPCM information and the intra BDPCM direction information are parsed for a luma component regardless of a chroma component.

4. 2. The method of claim 1, wherein the BDPCM activity information is signaled in a sequence.

5. If the intra BDPCM information indicates that BDPCM is applied to the current block, then the transform skip information of the transform block corresponding to the current block is not parsed from the bitstream; The method of claim 1, wherein the transform skip information indicates that no transform is applied to a block corresponding to the transform skip information when the value of the transform skip information is a first speculated value.

6. inferring the transform skip information to the first inferred value if the transform skip information does not exist and the intra BDPCM information indicates that BDPCM is applied to the current block; 6. The method of claim 5, further comprising: inferring the transform skip information to a second inferred value if the transform skip information does not exist and the intra BDPCM information indicates that BDPCM is not applied to the current block.

7. 2. The method of claim 1, wherein the intra BDPCM direction information indicates one of a horizontal direction and a vertical direction.

8. If the intra BDPCM direction information is 0, selecting an intra prediction mode corresponding to a horizontal direction from among a plurality of intra modes as the intra prediction mode of the current block; and if the intra BDPCM direction information is 1, selecting an intra prediction mode corresponding to a vertical direction from among a plurality of intra modes as the intra prediction mode of the current block.

9. The method of claim 8, wherein the intra-prediction mode of the current block is used to determine the intra-prediction mode of a neighboring block that is reconstructed after the current block.

10. A video signal processing apparatus for decoding video includes a processor and a memory; The processor, based on the instruction words stored in the memory, Parse BDPCM activation information indicating whether block-based delta pulse code modulation (BDPCM) is activated from the bitstream; parsing intra-BDPCM information indicating whether BDPCM is applied to the current block from the bitstream if the BDPCM activation information indicates activation of BDPCM, the width of the current block is less than or equal to a first value, and the height of the current block is less than or equal to a second value; If the intra BDPCM information indicates that BDPCM is applied to the current block, parsing intra BDPCM direction information for the current block from the bitstream; a video signal processing device for reconstructing the current block based on the intra BDPCM direction information;

11. 11. The video signal processing apparatus according to claim 10, wherein the first value and the second value are maximum block sizes that allow transform skipping.

12. 11. The video signal processing apparatus of claim 10, wherein the intra BDPCM information and the intra BDPCM direction information are parsed for a luma component regardless of a chroma component.

13. 11. The video signal processing apparatus of claim 10, wherein the BDPCM activity information is signaled in a sequence.

14. If the intra BDPCM information indicates that BDPCM is applied to the current block, then the transform skip information of the transform block corresponding to the current block is not parsed from the bitstream; The video signal processing apparatus of claim 10 , wherein the transform skip information indicates that, when a value of the transform skip information is a first inferred value, no transform is applied to the block corresponding to the transform skip information.

15. The processor, based on the instruction words stored in the memory, If the transform skip information does not exist and the intra BDPCM information indicates that BDPCM is applied to the current block, inferring the transform skip information to the first inferred value; 15. The video signal processing apparatus of claim 14, wherein if the transform skip information does not exist and the intra BDPCM information indicates that BDPCM is not applied to the current block, the transform skip information is inferred to a second inferred value.

16. 11. The video signal processing apparatus of claim 10, wherein the intra BDPCM direction information indicates one of a horizontal direction and a vertical direction.

17. The processor, based on the instruction words stored in the memory, If the intra BDPCM direction information is 0, an intra prediction mode corresponding to a horizontal direction among a plurality of intra modes is selected as the intra prediction mode of the current block; The video signal processing apparatus of claim 16, wherein, when the intra BDPCM direction information is 1, an intra prediction mode corresponding to a vertical direction among a plurality of intra modes is selected as the intra prediction mode of the current block.

18. The video signal processing apparatus of claim 17, wherein the intra-prediction mode of the current block is used to determine the intra-prediction modes of neighboring blocks reconstructed after the current block.

19. 1. A method of processing a video signal for encoding, comprising: generating BDPCM activation information indicating whether block-based delta pulse code modulation (BDPCM) is activated; generating intra BDPCM information indicating whether BDPCM is applied to the current block if the BDPCM activation information indicates activation of BDPCM, the width of the current block is less than or equal to a first value, and the height of the current block is less than or equal to a second value; and generating intra BDPCM direction information for the current block if the intra BDPCM information indicates that BDPCM is applied to the current block. generating a bitstream based on the BDPCM activity information, the intra BDPCM information, and the intra BDPCM direction information; 1. A method for processing a video signal, comprising:

20. 20. The method of claim 19, wherein if the intra BDPCM information indicates that BDPCM is applied to the current block, transform skip information of the transform block corresponding to the current block is not generated.

21. A video signal processing apparatus for encoding includes a processor and a memory; The processor, based on the instruction words stored in the memory, Generate BDPCM activation information indicating whether block-based delta pulse code modulation (BDPCM) is activated; generating intra-BDPCM information indicating whether BDPCM is applied to the current block when the BDPCM activation information indicates activation of BDPCM, the width of the current block is equal to or smaller than a first value, and the height of the current block is equal to or smaller than a second value; if the intra BDPCM information indicates that BDPCM is to be applied to the current block, generating intra BDPCM direction information for the current block; a video signal processing device for generating a bitstream based on the BDPCM activity information, the intra BDPCM information, and the intra BDPCM direction information;

22. 22. The video signal processing apparatus of claim 21, wherein if the intra BDPCM information indicates that BDPCM is applied to the current block, transform skip information of the transform block corresponding to the current block is not generated.

23. generating BDPCM activation information indicating whether block-based delta pulse code modulation (BDPCM) is activated; generating intra-BDPCM information indicating whether BDPCM is applied to the current block when the BDPCM activation information indicates activation of BDPCM, the width of the current block is less than or equal to a first value, and the height of the current block is less than or equal to a second value; generating intra BDPCM direction information for the current block if the intra BDPCM information indicates that BDPCM is applied to the current block; generating a bitstream based on the BDPCM activity information, the intra BDPCM information, and the intra BDPCM direction information; A computer-readable recording medium on which an encoded video signal including:

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