RU2776033C1 - Method for encoding the conversion coefficient based on high-frequency zeroing and equipment therefor - Google Patents

Abstract

FIELD: encoding.

SUBSTANCE: invention relates to image encoding tools. Residual discrete samples are obtained for the current block. Conversion coefficients are obtained for the current block based on the residual discrete samples for the current block. The residual information associated with the conversion coefficients is encoded. The current block therein includes an area of low-frequency conversion coefficients, including at least one significant conversion coefficient, and an area other than the area of low-frequency conversion coefficients, including a zero conversion coefficient. The residual information includes the prefix information of the last significant coefficient and the suffix information of the last significant coefficient with respect to the position of the last non-zero conversion coefficient from the conversion coefficients for the current block. The position of the last non-zero conversion coefficient is based on the prefix code word and the suffix information of the last significant coefficient.

EFFECT: increase in the efficiency of encoding.

16 cl, 13 dwg, 13 tbl

Description

State of the art

The technical field to which the invention belongs

[1] The present disclosure relates to an image coding technology, and more specifically, to a method for encoding a transform coefficient based on high-frequency nulling in an image coding system, and equipment therefor.

Description of the prior art

[2] Nowadays, the demand for high-quality high-definition images/videos, such as 4K, 8K or even higher ultra-high definition (UHD) images/videos, is growing in various fields of technology. As image/video data becomes higher resolution and higher quality, the amount of information or bits to be transmitted increases compared to conventional image data. Therefore, when image data is transmitted using a medium such as a conventional wired/wireless broadband line, or image/video data is stored using an existing storage medium, transmission costs and storage costs increase therefor.

[3] Additionally, nowadays, the interest and demand for immersive media such as virtual reality (VR), artificial reality (AR) or hologram content, etc. is growing, and broadcasting for images/videos having image features , different from the features of the actual images, such as the game image, is increased.

[4] Accordingly, there is a need for a high-performance image/video compression technology for efficiently compressing and transmitting or storing and reproducing high-quality high-resolution image/video information having various features as described above.

The essence of the invention

[5] The technical problem to be solved by the present disclosure is to provide a method and equipment that improves image coding efficiency.

[6] Another technical problem to be solved by the present disclosure is to provide a method and equipment that improves the efficiency of residual coding.

[7] Yet another technical problem to be solved by the present disclosure is to provide a method and equipment that improves coding efficiency at the transform coefficient level.

[8] Yet another technical problem to be solved by the present disclosure is to provide a method and equipment that improves residual coding efficiency by high-frequency nulling-based transform coefficient coding.

[9] Yet another problem to be solved by the present disclosure is to provide a method and equipment that encodes position information of the last significant coefficient in the current block (or current transform block) based on high frequency nulling.

[10] Yet another technical problem to be solved by the present disclosure is to provide a method and equipment that extracts the maximum length of a codeword representing the last significant transform coefficient based on the size of a region in the current block to which no high-frequency nulling is applied. when the transform coefficients for the current block (or current transform block) are encoded based on high-frequency nulling.

[11] Yet another technical problem to be solved by the present disclosure is to provide a method and equipment that binarizes the last significant coefficient prefix information and the last significant coefficient suffix information when high frequency nulling is performed.

[12] According to an example of the present disclosure, an image decoding method is provided, which is performed by decoding equipment. The method includes receiving a bitstream including residual information; extracting quantized transform coefficients for the current block based on the residual information included in the bitstream; extracting transform coefficients for the current block from the quantized transform coefficients based on an inverse quantization process; extracting residual samples for the current block by applying an inverse transform to the extracted transform coefficients; and generating a reconstructed frame based on the residual samples for the current block, wherein each of the transform coefficients for the current block is associated with a high frequency transform coefficient region consisting of a transform coefficient of 0, or with a low frequency transform coefficient region including at least one significant transform coefficient, the residual information includes the last significant coefficient prefix information and the last significant coefficient suffix information regarding the position of the last non-zero transform coefficient among the transform coefficients for the current block, the position of the last non-zero transform coefficient is determined based on the prefix codeword that represents the prefix information the last significant coefficient and the suffix information of the last significant coefficient, and the maximum length of the prefix codeword is determined based on the area size low-frequency conversion coefficients.

[13] According to another example of the present disclosure, decoding equipment is provided to perform image decoding. The decoding equipment includes an entropy decoder that receives a bitstream including residual information and extracts quantized transform coefficients for a current block based on the residual information included in the bitstream; a dequantizer that extracts transform coefficients for the current block from the quantized transform coefficients based on an inverse quantization process; an inverse transform that extracts residual samples for the current block by applying an inverse transform to the extracted transform coefficients; and an adder that generates a reconstructed frame based on the residual samples for the current block, wherein each of the transform coefficients for the current block is associated with a high frequency transform coefficient region consisting of a transform coefficient of 0, or with a low frequency transform coefficient region including at least least one significant transform coefficient, the residual information includes the last significant coefficient prefix information and the last significant coefficient suffix information regarding the position of the last non-zero transform coefficient among the transform coefficients for the current block, the position of the last non-zero transform coefficient is determined based on the prefix codeword, which represents the last significant coefficient prefix information and the last significant coefficient suffix information, and the maximum length of the prefix codeword is determined based on times a measure of the region of low-frequency transform coefficients.

[14] According to yet another example of the disclosure, an image encoding method is provided, which is performed by encoding equipment. The method includes extracting residual samples for the current block; extracting transform coefficients for the current block by transforming the residual samples for the current block; extracting quantized transform coefficients from the transform coefficients based on the quantization process; and encoding the residual information including information regarding the quantized transform coefficients, wherein each of the transform coefficients for the current block is associated with a high frequency transform coefficient region consisting of a transform coefficient of 0, or with a low frequency transform coefficient region including at least , one significant transform coefficient, the residual information includes the last significant coefficient prefix information and the last significant coefficient suffix information regarding the position of the last non-zero transform coefficient among the transform coefficients for the current block, the position of the last non-zero transform coefficient is based on the prefix codeword that represents the information the last significant coefficient prefix and the last significant coefficient suffix information, and the maximum length of the prefix codeword is determined by o again the size of the region of low-frequency transform coefficients.

[15] According to yet another example of the present disclosure, coding equipment is provided for performing image coding. The encoding hardware includes a subtractor that extracts residual samples for the current block; a transformer that extracts transform coefficients for the current block by transforming the residual samples for the current block; a quantizer that extracts quantized transform coefficients from the transform coefficients based on the quantization process; and an entropy encoder that encodes residual information including information about quantized transform coefficients, wherein each of the transform coefficients for the current block is associated with a high frequency transform coefficient region consisting of a transform coefficient of 0, or with a low frequency transform coefficient region including , at least one significant transform coefficient, the residual information includes the last significant coefficient prefix information and the last significant coefficient suffix information regarding the position of the last non-zero transform coefficient among the transform coefficients for the current block, the position of the last non-zero transform coefficient is based on the prefix codeword , which represents the last significant coefficient prefix information and the last significant coefficient suffix information, and the maximum length of the prefix code words is determined based on the size of the region of low-frequency transform coefficients.

[16] According to yet another example of the present disclosure, a decoder-readable storage medium is provided that stores information regarding instructions that instruct video decoding equipment to perform decoding methods according to some examples.

[17] According to still another example of the present disclosure, a decoder-readable storage medium is provided that stores information on instructions that instruct video decoding equipment to perform the decoding method according to the example. The decoding method according to the example includes receiving a bit stream including residual information; extracting quantized transform coefficients for the current block based on the residual information included in the bitstream; extracting transform coefficients for the current block from the quantized transform coefficients based on an inverse quantization process; extracting residual samples for the current block by applying an inverse transform to the extracted transform coefficients; and generating a reconstructed frame based on the residual samples for the current block, wherein each of the transform coefficients for the current block is associated with a high frequency transform coefficient region consisting of a transform coefficient of 0, or with a low frequency transform coefficient region including at least one significant transform coefficient, the residual information includes the last significant coefficient prefix information and the last significant coefficient suffix information regarding the position of the last non-zero transform coefficient among the transform coefficients for the current block, the position of the last non-zero transform coefficient is determined based on the prefix codeword that represents the prefix information the last significant coefficient and the suffix information of the last significant coefficient, and the maximum length of the prefix codeword is determined based on the area size low-frequency conversion coefficients.

[18] According to the present disclosure, the overall efficiency of image/video compression can be improved.

[19] According to the present disclosure, it is possible to improve the efficiency of residual coding.

[20] According to the present disclosure, it is possible to improve coding efficiency at the level of transform coefficients.

[21] According to the present disclosure, it is possible to improve the efficiency of residual coding by encoding a transform coefficient based on high frequency nulling (or high frequency nulling).

[22] According to the present disclosure, it is possible to improve image coding efficiency by encoding the position information of the last significant transform coefficient in the current block (or current transform block) based on high-frequency nulling.

[23] According to the present disclosure, it is possible to improve image coding efficiency by extracting the maximum length of a codeword representing the last significant transform coefficient based on the size of an area in the current block to which no high-frequency nulling is applied when the transform coefficients for the current block (or the current block transforms) are encoded based on high-frequency nulling.

[24] According to the present disclosure, when high-frequency nulling is applied by performing binarization on the syntax element based on the size of the low-frequency nulling region (or the region to which high-frequency nulling is not applied), it is possible to perform coding more efficiently and improve the throughput of CABAC by reducing the number of context-encoded permission elements.

Brief description of the drawings

[25] FIG. 1 schematically represents an example of a video/image coding system to which the present disclosure may apply.

[26] FIG. 2 is a diagram schematically describing the configuration of video/image coding equipment to which the present disclosure may apply.

[27] FIG. 3 is a diagram schematically describing the configuration of video/image decoding equipment to which the present disclosure may be applied.

[28] FIG. 4A and 4B are a drawing for explaining the configuration and operation of an entropy encoder according to an example.

[29] FIG. 5A and 5B are drawings for explaining the configuration and operation method of the entropy decoder according to an example.

[30] FIG. 6 is a drawing for explaining high frequency nulling according to an example.

[31] FIG. 7 is a flowchart showing the operation of the encoding equipment according to the example.

[32] FIG. 8 is a block diagram showing a configuration of an encoding equipment according to an example.

[33] FIG. 9 is a flowchart showing the operation of the decoding equipment according to an example.

[34] FIG. 10 is a block diagram showing a configuration of decoding equipment according to an example.

[35] FIG. 11 represents an example of a content streaming system to which the disclosure of this document may apply.

Detailed description of embodiments

[36] According to an example of the present disclosure, an image decoding method is provided, which is performed by decoding equipment. The method includes receiving a bitstream including residual information; extracting quantized transform coefficients for the current block based on the residual information included in the bitstream; extracting transform coefficients for the current block from the quantized transform coefficients based on an inverse quantization process; extracting residual samples for the current block by applying an inverse transform to the extracted transform coefficients; and generating a reconstructed frame based on the residual samples for the current block, wherein each of the transform coefficients for the current block is associated with a high frequency transform coefficient region consisting of a transform coefficient of 0, or with a low frequency transform coefficient region including at least one significant transform coefficient, the residual information includes the last significant coefficient prefix information and the last significant coefficient suffix information regarding the position of the last non-zero transform coefficient among the transform coefficients for the current block, the position of the last non-zero transform coefficient is determined based on the prefix codeword that represents the prefix information the last significant coefficient and the suffix information of the last significant coefficient, and the maximum length of the prefix codeword is determined based on the area size low-frequency conversion coefficients.

[37] Although the present disclosure is subject to various modifications and includes various embodiments, its specific embodiments are shown in the drawings by way of example and are described in detail below. However, it is not intended to limit the present disclosure to the specific embodiments disclosed herein. The terms used herein are for the purpose of describing specific embodiments only and are not intended to limit the technical idea of the present disclosure. Singular forms may include plural forms unless the context clearly indicates otherwise. Terms such as "comprise", "include" and the like are intended to indicate that there are features, numbers, steps, operations, elements, components, or combinations of the foregoing used in the description below, and therefore, it should not be understood that the presence or addition of one or more other features, numbers, steps, operations, elements, components, or combinations of the above is precluded.

[38] Meanwhile, each component in the drawings described herein is independently illustrated for convenience of description with respect to characteristic functions different from each other, and yet, it is not implied that each component is implemented by separate hardware or software. security. For example, any two or more of these components may be combined to form one component, and any one component may be split into multiple components. Embodiments in which the components are combined and/or separated should fall within the scope of the patent law of the present disclosure, provided that they do not depart from the spirit of the present disclosure.

[39] Hereinafter in this document, the preferred embodiments of the present disclosure are explained in more detail with reference to the accompanying drawings. Hereinafter in this document, identical reference numbers are used for identical components in the drawings, and repeated descriptions for identical components may be omitted.

[40] FIG. 1 schematically represents an example of a video/image coding system to which the present disclosure may apply.

[41] This document relates to video/image coding. For example, the methods/embodiments disclosed in this document may be applied to the method disclosed in the Universal Video Coding (VVC) standard, the EVC (Fundamental Video Coding) standard, the AOMedia Video 1 (AV1) standard, the second generation audio/video coding standard. (AVS2) or next generation video/image coding standard (eg H.267 or H.268 etc.).

[42] This document presents various embodiments of video/image coding, and the embodiments may be performed in combination with each other unless otherwise noted.

[43] In this document, video can mean a sequence of images over time. A frame generally means a unit representing one image in a particular time zone, and a slice/tile is a unit constituting a frame when encoded. A slice/tile may include one or more coding tree units (CTUs). One frame may consist of one or more slices/tiles. One frame may consist of one or more tile groups. One group of tiles may include one or more tiles. A brick may represent a rectangular area of CTU rows in a tile in a frame. A tile can be segmented into multiple bricks, each consisting of one or more rows of CTUs in the tile. A tile that does not segment into multiple bricks may also be referred to as a "brick". Brickscan is a particular sequential ordering of CTUs segmenting a frame, where CTUs are ordered sequentially in a CTU raster scan in a brick, bricks within a tile are ordered sequentially in a tile bricks raster scan, and tiles in a frame are ordered sequentially in a frame tile raster scan. A tile is a rectangular area of the CTU in a particular column of tiles and a particular row of tiles in a frame. The tile column is a rectangular area of CTUs having a height equal to the height of the frame and a width specified by syntax elements in the frame parameter set. The row of tiles is a rectangular area of CTUs having a height indicated by syntax elements in the frame parameter set and a width equal to the frame width. Tile scanning is a particular sequential ordering of CTUs segmenting a frame, whereby CTUs are ordered sequentially in a raster scan of the CTUs in a tile, while tiles in a frame are ordered sequentially in a raster scan of the tiles of the frame. A slice includes an integer number of frame bricks that can only be contained in one NAL unit. A slice can either consist of a certain number of full tiles, or only a rigid sequence of full bricks of a single tile. Tile groups and slices can be used interchangeably throughout this document. For example, in this document, a tile group/tile group header may be referred to as a "slice/slice header".

[44] A pixel or pel can mean the smallest unit that makes up one frame (or image). In addition, "discrete reading" ("sampling") can be used as a term corresponding to a pixel. A sample may generally represent a pixel or a pixel value, and may represent only a pixel/pixel value of a luma component, or only a pixel/pixel value of a chroma component.

[45] The unit may represent a basic image processing unit. The unit may include at least one of a specific area of the frame and information associated with the area. One unit may include one luminance block and two chrominance blocks (eg, cb, cr). The unit can be used interchangeably with terms such as block or zone in some cases. In general, an MxN block may include samples (or arrays of samples) or a set (or array) of transform coefficients of M columns and N rows.

[46] In this document, the terms "/" and "" are to be interpreted as indicating "and/or". For example, the expression "A/B" can mean "A and/or B". Additionally, "A, B" may mean "A and/or B". Additionally, "A/B/C" may mean "at least one of A, B and/or C". In addition, "A/B/C" may mean "at least one of A, B and/or C".

[47] Additionally, in the document, the term "or" should be interpreted as indicating "and/or". For example, the expression "A or B" may contain 1) only A, 2) only B, and/or 3) both A and B. In other words, the term "or" in this document is to be interpreted as indicating "in addition or alternatively" .

[48] Referring to FIG. 1, the video/image coding system may include a first device (source device) and a second device (receiver device). The source device may deliver the encoded information or video/image data in file or streaming form to the destination device via a digital storage medium or a network.

[49] The source device may include a video source, encoding equipment, and a transmitter. The receiver may include a receiver, decoding hardware, and a renderer. The encoding equipment may be referred to as "video/image coding equipment", and the decoding equipment may be referred to as "video/image decoding equipment". The transmitter may be included in the encoding equipment. The receiver may be included in decoding equipment. The renderer may include a display, and the display may be configured as a separate device or an external component.

[50] A video source may acquire a video/image through a process of capturing, synthesizing, or generating a video/image. The video source may include a video/image capture device and/or a video/image generation device. The video/image capture device may include, for example, one or more cameras, video/image archives including previously captured videos/images, and the like. The video/image generation apparatus may include, for example, computers, tablet computers, and smartphones, and may (electronically) generate video/images. For example, the virtual video/image may be generated via a computer or the like. In this case, the video/image capturing process may be replaced by a linked data generation process.

[51] The encoding equipment may encode the input video/image. The encoding equipment may perform a series of procedures such as prediction (prediction), transformation, and quantization for compression and encoding efficiency. Encoded data (encoded video/picture information) may be output in the form of a bit stream.

[52] The transmitter may transmit information or coded image/image data output in the form of a bit stream to the receiver of the receiving device via a digital storage medium or a network in the form of a file or streaming. The digital storage medium may include various storage media such as USB, SD, CD, DVD, Blu-ray, HDD, SSD, and the like. The transmitter may include an element for generating a media file via a predetermined file format and may include an element for transmission via a broadcast/communication network. The receiver may receive/retrieve the bitstream and transmit the received bitstream to the decoding equipment.

[53] The decoding equipment can decode the video/image by performing a sequence of procedures such as dequantization, inverse transformation, and prediction corresponding to the operation of the encoding equipment.

[54] The rendering module may prepare a decoded video/image by rendering. The rendered video/image can be displayed through the display.

[55] FIG. 2 is a diagram schematically describing the configuration of video/image coding equipment to which the present disclosure may apply. Hereinafter in this document, what is referred to as "video encoding equipment" may include image encoding equipment.

[56] Referring to FIG. 2, the encoding equipment 200 includes an image segmentation module 210, a prediction module 220, a residual processor 230 and an entropy encoder 240, an adder 250, a filter 260, and a memory 270. The prediction module 220 may include an inter (inter) prediction module 221 and module 222 internal (intra) prediction. Residual processor 230 may include a transformer 232, a quantizer 233, a dequantizer 234, and an inverse transformer 235. Residual processor 230 may further include a subtractor 231. Adder 250 may be referred to as a "rebuilder" or "recovered block generator". Image segmentation module 210, prediction module 220, residual processor 230, entropy encoder 240, adder 250, and filter 260 may be configured by at least one hardware component (e.g., chipset or encoder processor) according to an embodiment. In addition, the memory 270 may include a decoded frame buffer (DPB) or may be configured by a digital storage medium. The hardware component may further include a storage device 270 as an internal/external component.

[57] The image segmentation unit 210 may segment an input image (either a frame or a picture) input to the encoding equipment 200 into one more processing units. For example, a processing unit may be referred to as a "coding unit (CU)". In this case, a coding unit may be recursively segmented according to a quadtree, binary tree, and ternary tree (QTBTTT) structure from a coding tree unit (CTU) or a largest coding unit (LCU). For example, one coding unit may be segmented into multiple coding units of greater depth based on a quadtree structure, a binary tree structure, and/or a ternary structure. In this case, for example, a quadtree structure may be applied first, and a binary tree structure and a ternary structure may subsequently be applied. Alternatively, a binary tree structure may be applied first. The encoding procedure according to this document may be performed on the basis of a final encoding unit that is no longer segmented. In this case, the largest coding unit may be used as the final coding unit based on the coding efficiency according to the characteristics of the images, or if necessary, the coding unit may be recursively segmented into coding units of greater depth, and the coding unit having the optimal size may be used as the final coding units. Here, the encoding procedure may include a prediction, transformation, and restoration procedure, which is described below. As another example, the processing unit may further include a prediction unit (PU) or a transformation unit (TU). In this case, the prediction unit and the transformation unit may be split or segmented from the above final coding unit. The prediction unit may be a selective prediction unit, and the transform unit may be a unit for extracting a transform coefficient and/or a unit for extracting a residual signal from a transform coefficient.

[58] The unit can be used interchangeably with terms such as block or zone in some cases. In general, an MxN block may represent a set of samples or transform coefficients consisting of M columns and N rows. The sample, in general, may represent a pixel or pixel value, may represent only a pixel/pixel value of the luminance signal component, or represent only a pixel/pixel value of the chrominance signal component. Sampling can be used as a term corresponding to one frame (or image) for a pixel or pel.

[59] In the coding equipment 200, the prediction signal (predicted block, array of predictive samples) output from the inter prediction unit 221 or intra prediction unit 222 is subtracted from the input image signal (original block, array of original samples) to generate a residual signal ( residual block, residual sample array), and the generated residual signal is passed to converter 232. In this case, as shown, a module for subtracting the prediction signal (predicted block, predictive sample array) from the input image signal (original block, original sample array) in encoder 200 may be referred to as "subtractor 231". The prediction module may perform prediction on a block to be processed (hereinafter referred to as "current block") and generate a prediction block including prediction samples for the current block. The prediction module may determine whether intra prediction or inter prediction is applied based on the current block or CU. As described below in the description of each prediction mode, the prediction module may generate various prediction-related information, such as prediction mode information, and pass the generated information to the entropy encoder 240. The prediction information may be encoded in the entropy encoder 240 and output in the form of a stream. bits.

[60] The intra prediction module 222 may predict the current block by referring to the samples in the current frame. The inversion samples may be located in the surroundings of the current block, or may be independently located according to the prediction mode. In intra prediction, the prediction modes may include a plurality of non-directional modes and a plurality of directional modes. The non-directional mode may include, for example, a DC mode and a planar mode. The directional mode may include, for example, 33 directional prediction modes or 65 directional prediction modes according to the granularity of the prediction direction. However, this is just an example, more or less directional prediction modes may be used depending on the setting. The intra prediction unit 222 may determine the prediction mode applied to the current block by using the prediction mode applied to the neighboring block.

[61] The inter prediction unit 221 may derive a predicted block for the current block based on a reference block (reference sample array) indicated by a motion vector for the reference frame. Here, in order to reduce the amount of motion information transmitted in the inter-prediction mode, the motion information may be predicted in units of blocks, sub-blocks, or samples based on the correlation of the motion information between the adjacent block and the current block. The motion information may include a motion vector and a reference frame index. The motion information may further include inter-prediction direction information (L0 prediction, L1 prediction, bi-prediction, etc.). In the case of inter prediction, an adjacent block may include a spatial adjacent block present in the current picture and a temporal adjacent block present in the reference picture. The reference frame including the reference block and the reference frame including the temporal neighbor block may be the same or different. The temporal neighbor block may be referred to as a "collocated reference block", "collocated CU (colCU)" or the like, and a reference frame including the temporal neighbor block may be referred to as a "collocated frame (colPic)". For example, the inter-prediction unit 221 may configure a list of motion information candidates based on neighboring blocks, and generate information indicating which candidate is used to derive the motion vector and/or the reference frame index of the current block. Inter prediction may be performed based on various prediction modes. For example, in the case of the skip mode and the merge mode, the inter prediction unit 221 may use the neighboring block motion information as the current block motion information. In the skip mode, unlike the merge mode, the residual signal may not be transmitted. In the case of a motion vector prediction (MVP) mode, the motion vector of an adjacent block may be used as a motion vector predictor, and the motion vector of the current block may be indicated by signaling a motion vector difference.

[62] The prediction module 220 may generate a prediction signal based on various prediction methods described below. For example, the prediction module may not only apply intra prediction or inter prediction to predict one block, but also apply both intra prediction and inter prediction at the same time. This may be referred to as "combined mutual and intra prediction (CIIP)". In addition, the prediction module may be based on an intra-block copy (IBC) prediction mode or a palette mode for block prediction. The IBC prediction mode or palette mode can be used for image/video coding of game content and the like, such as screen content coding (SCC). IBC essentially performs prediction in the current frame, but may be performed similar to inter-prediction in which the reference block is retrieved in the current frame. Thus, the IBC may use at least one of the inter-prediction technologies described in this document. Palette mode can be considered as an example of intra coding or intra prediction. When the palette mode is applied, a sample value in a frame may be signaled based on information regarding the palette table and palette index.

[63] The prediction signal generated by the prediction module (including the inter prediction module 221 and/or the intra prediction module 222) may be used to generate a recovered signal or generate a residual signal. Converter 232 may generate transform coefficients by applying a transform technique to the residual signal. For example, the transform technology may include at least one of Discrete Cosine Transform (DCT), Discrete Sine Transform (DST), Karhunen-Loeve Transform (KLT), Graph Based Transform (GBT), or Conditionally Nonlinear Transform (CNT). ). Here, GBT means a transformation obtained from a graph when relationship information between pixels is represented by a graph. CNT means a transform generated based on a predictive signal generated using all previously reconstructed pixels. In addition, the transformation process may be applied to square pixel blocks having the same size, or may be applied to blocks having a variable size rather than square ones.

[64] The quantizer 233 may quantize the transform coefficients and pass them to the entropy encoder 240, and the entropy encoder 240 may encode the quantized signal (information regarding the quantized transform coefficients) and output a bitstream. The information regarding the quantized transform coefficients may be referred to as "residual information". The quantizer 233 may repackage the block quantized transform coefficients into one-dimensional vector form based on the scan order of the coefficients, and generate information about the quantized transform coefficients based on the quantized transform coefficients in one-dimensional vector form. Information regarding transform coefficients may be generated. Entropy encoder 240 may perform various coding methods such as exponential Golomb code, context adaptive variable length coding (CAVLC), context adaptive binary arithmetic coding (CABAC), and the like, for example. Entropy encoder 240 may encode information needed for video/image reconstruction other than quantized transform coefficients (eg, syntax element values, etc.) together or separately. Encoded information (eg, encoded video/image information) may be transmitted or stored in NAL (Network Abstraction Layer) units in the form of a bit stream. The video/image information may further include information regarding various parameter sets such as an adaptation parameter set (APS), a frame parameter set (PPS), a sequence parameter set (SPS), or a video parameter set (VPS). In addition, the video/image information may further include general restriction information. In this document, information and/or syntax elements transmitted/signaled from encoding equipment to decoding equipment may be included in video/frame information. The video/image information may be encoded through the above-described encoding procedure and included in the bitstream. The bit stream may be transmitted over a network or may be stored on a digital storage medium. The network may include a broadcast network and/or a communication network, and the digital storage medium may include various storage media such as USB, SD, CD, DVD, Blu-ray, HDD, SSD, and the like. A transmitter (not shown), transmitting a signal output from the entropy encoder 240, and/or a storage module (not shown) storing the signal may be included as an internal/external member of the encoding equipment 200, and alternatively, a transmitter may be included in the entropy encoder 240 .

[65] The quantized transform coefficients output from quantizer 233 may be used to generate a predictive signal. For example, the residual signal (residual block or residual samples) may be recovered by applying dequantization and inverse transform to the quantized transform coefficients via dequantizer 234 and inverse transform 235. Summer 250 adds the recovered residual signal to the predictive signal output from inter prediction module 221 or module 222 intra-prediction to generate a reconstructed signal (recovered frame, reconstructed block, reconstructed sample array). If there is no remainder for a block to be processed, such as in a case in which the skip mode is applied, the predicted block may be used as the reconstructed block. The adder 250 may be referred to as a "recovery module" or "recovered block generator". The generated recovered signal may be used to intra-predict the next block to be processed in the current frame, and may be used to inter-predict the next frame through filtering as described below.

[66] Meanwhile, luminance chrominance scaling (LMCS) transform may be applied during encoding and/or frame reconstruction.

[67] The filter 260 can improve subjective/objective image quality by applying filtering to the reconstructed signal. For example, filter 260 may generate a modified reconstructed frame by applying various filtering methods to the reconstructed frame and store the modified reconstructed frame in memory 270, namely the DPB of memory 270. Various filtering methods may include, for example, filtering to deblock , sampled adaptive bias, adaptive loop filter, bilateral filter, etc. The filter 260 may generate various filtering-related information and pass the generated information to the entropy encoder 240 as described below in the description of each filtering method. Filtering related information may be encoded by entropy encoder 240 and output in the form of a bitstream.

[68] The modified reconstructed frame transmitted to the memory 270 may be used as a reference frame in the inter prediction module 221 . When inter prediction is applied by the encoding equipment, prediction mismatch between the encoding equipment 200 and the decoding equipment can be eliminated, and encoding efficiency can be improved.

[69] The DPB of the memory 270 may store the modified reconstructed frame for use as a reference frame in the inter prediction module 221 . The memory 270 may store block motion information from which motion information in the current frame is extracted (or encoded) and/or motion information of blocks in the frame that have already been recovered. The stored motion information may be transmitted to the inter-prediction unit 221 and used as spatial neighbor block motion information or temporal neighbor block motion information. The memory 270 may store the recovered samples of the recovered blocks in the current frame and may pass the recovered samples to the intra prediction module 222 .

[70] FIG. 3 is a schematic diagram illustrating the configuration of video/image decoding equipment to which the embodiment(s) of the present document may be applied.

[71] Referring to FIG. 3, the decoding equipment 300 may include an entropy decoder 310, a residual processor 320, a prediction unit 330, an adder 340, a filter 350, a memory 360. The prediction unit 330 may include an inter prediction unit 331 and an intra prediction unit 332. Residual processor 320 may include a dequantizer 321 and an inverse converter 321. Entropy decoder 310, residual processor 320, predictor 330, adder 340, and filter 350 may be configured by a hardware component (eg, a chipset or decoder processor) according to an embodiment. In addition, the storage device 360 may include a decoded frame buffer (DPB) or may be configured with a digital storage medium. The hardware component may further include a storage device 360 as an internal/external component.

[72] When a bitstream including video/image information is input, the decoding equipment 300 can reconstruct an image corresponding to the process in which the video/image information is processed in the encoding equipment of FIG. 2. For example, decoding equipment 300 may extract units/blocks based on block segmentation-related information obtained from the bit stream. The decoding equipment 300 may perform decoding using a processing unit used in the encoding equipment. Thus, the decoding processing unit may, for example, be a coding unit, and the coding unit may be segmented according to a quadtree structure, a binary tree structure, and/or a ternary tree structure from the coding tree unit or the largest coding unit. One or more transformation units may be derived from a coding unit. The reconstructed image signal decoded and output by the decoding equipment 300 can be reproduced by the playback equipment.

[73] The decoding equipment 300 may receive a signal output from the encoding equipment of FIG. 2 in the form of a bitstream, and the received signal may be decoded via entropy decoder 310. For example, entropy decoder 310 may parse the bitstream to extract information (eg, video/image information) needed for image recovery (or frame recovery). The video/image information may further include information regarding various parameter sets such as an adaptation parameter set (APS), a frame parameter set (PPS), a sequence parameter set (SPS), or a video parameter set (VPS). In addition, the video/image information may further include general restriction information. The decoding equipment may further decode the frame based on the parameter set information and/or general constraint information. Signaling/receiving information and/or syntax elements described later in this document may be decoded, may be decoded by a decoding procedure, and obtained from a bitstream. For example, entropy decoder 310 decodes information in the bitstream based on an encoding method such as Exponential Golomb, CAVLC, or CABAC coding and output syntax elements required for image reconstruction and quantized transform coefficient values for the remainder. More specifically, the CABAC entropy decoding method may receive a bin corresponding to each syntax element in the bit stream, determine a context model using decoding target syntax element information, decoding target decoding block decoding information, or symbol/bin information decoded in the previous stage, and perform arithmetic decoding for the permission element by predicting the occurrence probability of the permission element according to the determined context model, and generating a symbol corresponding to the value of each syntax element. In this case, the CABAC entropy decoding method can update the context model by using the decoded symbol/bin information for the context model of the next symbol/bin after the context model is determined. Prediction related information from the information decoded by the entropy decoder 310 may be provided to the prediction unit (inter prediction unit 332 and intra prediction unit 331) and the residual value for which entropy decoding is performed in the entropy decoder 310, i. the quantized transform coefficients and associated parameter information may be input to residual processor 320. Residual processor 320 may extract the residual signal (residual block, residual samples, residual sample array). In addition, filtering information from the information decoded by the entropy decoder 310 may be provided to the filter 350. Meanwhile, a receiver (not shown) for receiving a signal output from the encoding equipment may be further configured as an internal/external member of the equipment 300 decoding equipment, or the receiver may be a component of the entropy decoder 310. Meanwhile, the decoding equipment according to this document may be referred to as "video/image/frame decoding equipment", and the decoding equipment may be classified into an information decoder (video/image/frame information decoder) and selective decoder (decoder of video/image/frame samples). The information decoder may include an entropy decoder 310, and the selective decoder may include at least one of a dequantizer 321, an inverse transform 322, an adder 340, a filter 350, a memory 360, an inter prediction unit 332, and an intra prediction unit 331. .

[74] The dequantizer 321 may dequantize the quantized transform coefficients and output the transform coefficients. The dequantizer 321 may recompose the quantized transform coefficients into a two-dimensional block form. In this case, the reassembly may be performed based on the coefficient scan order performed in the encoding equipment. The dequantizer 321 may perform dequantization on the quantized transform coefficients by using a quantization parameter (eg, quantization step size information) and obtain the transform coefficients.

[75] The detransformer 322 inversely transforms the transform coefficients to obtain a residual signal (residual block, array of residual samples).

[76] Prediction module 230 may perform prediction for the current block and may generate a predicted block including prediction samples for the current block. The prediction module may determine whether intra prediction or inter prediction is applied to the current block based on the prediction information output from the entropy decoder 310, and may determine a specific intra/inter prediction mode.

[77] Prediction module 320 may generate a predictive signal based on various prediction methods described below. For example, the prediction module may not only apply intra prediction or inter prediction in order to predict one block, but also apply intra prediction and inter prediction at the same time. This may be referred to as "combined mutual and intra prediction (CIIP)". In addition, the prediction module may be based on an intra-block copy (IBC) prediction mode or a palette mode for block prediction. The IBC prediction mode or palette mode can be used for image/video coding of game content and the like, such as screen content coding (SCC). IBC essentially performs prediction in the current frame, but may be performed similar to inter-prediction in which the reference block is retrieved in the current frame. Thus, the IBC may use at least one of the inter-prediction technologies described in this document. Palette mode can be considered as an example of intra coding or intra prediction. When the palette mode is applied, a sample value in a frame may be signaled based on information regarding the palette table and palette index.

[78] The intra prediction module 331 may predict the current block by referring to the samples in the current frame. The reference samples may be located in the surroundings of the current block, or may be independently located according to the prediction mode. In intra prediction, the prediction modes may include a plurality of non-directional modes and a plurality of directional modes. The intra prediction unit 331 may determine the prediction mode applied to the current block by using the prediction mode applied to the adjacent block.

[79] The inter prediction unit 332 may derive a predicted block for the current block based on a reference block (reference sample array) indicated by a motion vector for the reference frame. In this case, in order to reduce the amount of motion information transmitted in the inter-prediction mode, the motion information may be predicted in units of blocks, sub-blocks, or samples based on the correlation of the motion information between the adjacent block and the current block. The motion information may include a motion vector and a reference frame index. The motion information may further include inter-prediction direction information (L0 prediction, L1 prediction, bi-prediction, etc.). In the case of inter prediction, the neighbor block may include a spatial neighbor present in the current picture and a temporal neighbor present in the reference picture. For example, inter-prediction unit 332 may configure a motion information candidate list based on adjacent blocks, and derive the current block's motion vector and/or reference frame index based on the received candidate selection information. Inter prediction may be performed based on various prediction modes, and the prediction information may include information indicative of the inter prediction mode for the current block.

[80] The adder 340 may generate a reconstructed signal (recovered frame, reconstructed block, array of reconstructed samples) by summing the obtained residual signal with the predictive signal (predicted block, array of predicted samples) output from the prediction module (including the inter prediction module 332 and /or internal prediction module 331). If there is no remainder for the block to be processed, for example, when the skip mode is applied, the predicted block may be used as the reconstructed block.

[81] The adder 340 may be referred to as a "recovery module" or "recovered block generator". The generated recovered signal may be used for intra-prediction of the next block to be processed in the current frame, may be output by filtering as described below, or may be used for inter-prediction of the next frame.

[82] Meanwhile, luminance chrominance scaling (LMCS) transform may be applied in the frame decoding process.

[83] The filter 350 can improve subjective/objective image quality by applying filtering to the reconstructed signal. For example, filter 350 may generate a modified reconstructed frame by applying various filtering methods to the reconstructed frame and store the modified reconstructed frame in memory 360, namely the DPB of memory 360. Various filtering methods may include, for example, filtering to deblock , sampled adaptive bias, adaptive loop filter, bilateral filter, etc.

[84] The (modified) reconstructed frame stored in the DPB of the storage device 360 may be used as a reference frame in the inter prediction module 332 . The memory 360 may store block motion information from which motion information in the current frame is extracted (or decoded) and/or motion information of blocks in the frame that have already been recovered. The stored motion information may be transmitted to the inter-prediction unit 260 so that it is used as spatial neighbor block motion information or temporal neighbor block motion information. The memory device 360 may store the reconstructed samples of the reconstructed blocks in the current frame and pass the reconstructed samples to the intra prediction module 331 .

[85] In the present disclosure, the embodiments described in the filter 260, the inter prediction unit 221, and the intra prediction unit 222 of the coding equipment 200 may be identical to properly applied so that they correspond to the filter 350, the inter prediction unit 332, and the intra prediction unit 331 of the equipment 300 decoding. The same can also be applied to module 332 and module 331 internal prediction.

[86] As described above, prediction is performed in order to improve the compression efficiency when performing video encoding. Due to this, a predicted block including the predictive samples for the current block, which is the coding target block, can be generated. Here, the prediction block includes prediction samples in the spatial domain (or pixel domain). The predicted block can be identically retrieved in the encoding equipment and the decoding equipment, and the encoding equipment can improve image encoding efficiency by signaling to the decoding equipment not the original sample value of the original block itself, but information regarding the residual (residual information) between the original block and the predicted block . The decoding equipment can extract a residual block including residual samples based on the residual information, generate a reconstructed block including reconstruction samples by summing the residual block with the predicted block, and generate a reconstructed frame including the reconstructed blocks.

[87] The residual information may be generated through transformation and quantization procedures. For example, the encoding equipment can extract the residual block between the original block and the predicted block, extract transform coefficients by performing a transform procedure on the residual samples (array of residual samples) included in the residual block, and extract quantized transform coefficients by performing a quantization procedure on the transform coefficients, so that it can signal the associated residual information to the decoding equipment (via the bitstream). Here, the residual information may include value information, position information, transformation technology, transformation kernel, quantization parameter, and the like. quantized transformation coefficients. The decoding equipment may perform a quantization/dequantization procedure and extract residual samples (or block of residual samples) based on the residual information. The decoding equipment may generate a reconstructed block based on the predicted block and the residual block. The coding equipment may extract the residual block by dequantizing/inverse transforming the quantized transform coefficients for a reference for inter-prediction of the next frame, and may generate a reconstructed frame based on it.

[88] FIG. 4A and 4B are a drawing for explaining the configuration and operation of an entropy encoder according to an embodiment.

[89] Referring to FIG. 4A and 4B, the encoding equipment (entropy encoder) may perform a residual encoding procedure for the (quantized) transform coefficients. The coding equipment may perform residual coding for the (quantized) transform coefficients in the current block (in the current coding block (CB) or in the current transform block (TB)) according to the scan order, as described below in FIG. 6. The encoding equipment, for example, may generate and encode various syntax elements associated with the residual information as described in Table 1 below. S400 and S410 may be included in the residual information encoding procedure of FIG. 2.

[90] Tab. one

[91] The encoding equipment may perform binarization for syntax elements associated with the remainder, including last_sig_coeff_x_prefix and last_sig_coeff_y_prefix (S400); last_sig_coeff_x_prefix and last_sig_coeff_y_prefix may be derived based on the position of the last significant coefficient in the current block.

[92] last_sig_coeff_x_prefix and last_sig_coeff_y_prefix may represent an example of the last significant coefficient prefix information regarding the position of the last non-zero transform coefficient among the transform coefficients for the current block. More specifically, last_sig_coeff_x_prefix may represent an example of X-axis prefix information that is one of the last significant coefficient prefix information, and last_sig_coeff_y_prefix may represent an example of Y-axis prefix information that is one of the last significant coefficient prefix information.

[93] In this case, zero can be used as the value of cRiceParam. The encoding equipment may extract the bin string for each of last_sig_coeff_x_prefix and last_sig_coeff_y_prefix through a binarization procedure. The binarization procedure may be performed by a binarizer 242 in entropy encoder 240.

[94] According to an embodiment, a cMax value for each of last_sig_coeff_x_prefix and last_sig_coeff_y_prefix may be derived based on whether high frequency nulling is applied or not. Below in FIG. 6 describes a specific equation for extracting cMax; cMax may represent the maximum length of the codeword (bin string) extracted in the binarization procedure for last_sig_coeff_x_prefix or last_sig_coeff_y_prefix. By reducing the value of cMax, the length of the codeword for last_sig_coeff_x_prefix or last_sig_coeff_y_prefix can be effectively reduced. In addition, since the encoded bin reduced by codeword reduction is a context-encoded bin, an advantage in terms of image coding throughput can be provided.

[95] Meanwhile, binarization may continue for the remaining syntax elements of Table 1 according to a predetermined method. For example, binarization may be performed on transform_skip_flag, last_sig_coeff_x_suffix, last_sig_coeff_y_suffix, coded_sub_block_flag, sig_coeff_flag, par_level_flag, rem_abs_gt1_flag, rem_abs_gt2_flag, coeff_sign_flag, mts_idx, and the like. according to the fixed length code binarization process, and abs_remainder can be binarized corresponding to it.

[96] The encoding equipment may perform entropy encoding on syntax elements associated with residual encoding, including last_sig_coeff_x_prefix and last_sig_coeff_y_prefix (S410). The encoding hardware may perform entropy coding based on the bin string for each of last_sig_coeff_x_prefix and last_sig_coeff_y_prefix. The encoding equipment may perform context or bypass encoding of a bin string based on an entropy encoding technology such as context adaptive arithmetic coding (CABAC) or context adaptive variable length coding (CAVLC) and its output may be included in a bit stream. The entropy encoding procedure may be performed by the entropy encoding processor 244 in the entropy encoder 240. The bit stream may include various image/video decoding information such as prediction information and the like, except for residual information including information regarding last_sig_coeff_x_prefix and last_sig_coeff_y_prefix as described above. The bit stream may be transmitted to the decoding equipment via a (digital) storage medium or a network.

[97] FIG. 5A and 5B are a drawing for explaining the configuration and operation method of the entropy decoder according to the embodiment.

[98] Referring to FIG. 5A and 5B, the decoding equipment (entropy decoder) can extract (quantized) transform coefficients by decoding the encoded residual information. The decoding equipment can extract (quantized) transform coefficients by decoding the encoded residual information for the current block (current CB or current TB) as described below in FIG. 6. For example, the decoding equipment may decode the various syntax elements associated with such residual information recorded in Table 1, parse the values of the associated syntax elements, and extract (quantized) transform coefficients based on the value of the parsed syntax elements. S500-S510 may be included in a procedure that extracts the above-described (quantized) transform coefficients of FIG. 3.

[99] The decoding equipment may perform binarization on the syntax elements associated with the remainder, including last_sig_coeff_x_prefix and last_sig_coeff_y_prefix (S500). In this case, zero can be used as the value of cRiceParam. The encoding hardware may extract the available bin string for each available value of last_sig_coeff_x_prefix and last_sig_coeff_y_prefix via a binarization procedure. The binarization procedure may be performed by a binarizer 312 in the entropy decoder 310. According to an embodiment, a cMax value for each of last_sig_coeff_x_prefix and last_sig_coeff_y_prefix may be derived based on whether high frequency nulling is applied or not. Below in FIG. 6 describes a specific equation for extracting cMax.

[100] cMax may represent the maximum length of the codeword (string of bins) extracted in the binarization procedure for last_sig_coeff_x_prefix or last_sig_coeff_y_prefix. By reducing the value of cMax, the length of the codeword for last_sig_coeff_x_prefix or last_sig_coeff_y_prefix can be effectively reduced. In addition, since the encoded bin reduced by codeword reduction is a context-encoded bin, an advantage in terms of image coding throughput can be provided.

[101] Meanwhile, binarization may continue for the remaining syntax elements of Table 1 according to a predetermined method. For example, binarization may be performed on transform_skip_flag, last_sig_coeff_x_suffix, last_sig_coeff_y_suffix, coded_sub_block_flag, sig_coeff_flag, par_level_flag, rem_abs_gt1_flag, rem_abs_gt2_flag, coeff_sign_flag, mts_idx, and the like. according to the fixed length code binarization process, and abs_remainder can be binarized corresponding to it.

[102] The decoding equipment may perform entropy decoding on syntax elements associated with residual coding including last_sig_coeff_x_prefix and last_sig_coeff_y_prefix (S510). The decoding hardware may compare the retrieved bin string with the available bin strings when parsing and decoding each of the bins for last_sig_coeff_x_prefix in sequence. When the retrieved bin string is identical to one of the available bin strings, the value corresponding to the bin string may be retrieved as the value of last_sig_coeff_x_prefix. When the extracted bin string is not identical to any of the available bin strings, a comparison procedure may be performed after additional parsing and decoding of the next bit in the bitstream. Additionally, the decoding hardware may compare the retrieved bin string with the available bin strings when parsing and decoding each of the bins for last_sig_coeff_y_prefix in sequence. When the retrieved bin string is identical to one of the available bin strings, the value corresponding to the bin string may be retrieved as the value of last_sig_coeff_y_prefix. When the extracted bin string is not identical to any of the available bin strings, a comparison procedure may be performed after additional parsing and decoding of the next bit in the bitstream. Through these processes, without using a start bit or end bit for particular information (a particular syntax element) in the bit stream, information can be signaled using a variable length bit, whereby a relatively smaller bit can be assigned to a low value, thereby increasing overall coding efficiency.

[103] The decoding equipment may perform contextual or bypass decoding on each of the bins in the bin string from the bitstream based on entropy coding technology such as CABAC, CAVLC, and the like. The entropy decoding procedure may be performed by the entropy decoding processor 314 in the entropy decoder 310. The decoding hardware may extract the position of the last significant coefficient based on the last_sig_coeff_x_prefix value and the last_sig_coeff_y_prefix value. Specific calculation, for example, may be performed based on Table 2 below.

[104] Tab. 2

The column position of the last significant coefficient in the scan order in the LastSignificantCoeffX block of the transform is retrieved as follows: //If last_sig_coeff_x_suffix is not present, the following applies: LastSignificantCoeffX=last_sig_coeff_x_prefix // Otherwise (last_sig_coeff_x_suffix is present), the following applies: LastSignificantCoeffX=(1<<((last_sig_coeff_x_prefix> >1)-1))*(2+(last_sig_coeff_x_prefixand1))+last_sig_coeff_x_suffix // The row position of the last significant coeff in scan order in the LastSignificantCoeffY transform block is retrieved h as follows: // If last_sig_coeff_y_suffix is not present, the following applies: LastSignificantCoeffY=last_sigcoeff_y_prefix / / Otherwise (last_sig_coeff_y_suffix is present), the following applies: LastSignificantCoeffY=(1<<((last_sig_coeff_y_prefix>>1)-))*(2+(last_sig_c-oeff_y_prefixand1))+last_sig_coeff_y_suffix

[105] In Table 2, LastSignificantCoeffX may represent the x-axis position of the last non-zero significant coefficient in the current block (transform), and LastSignificantCoeffY may represent the y-axis position of the last non-zero significant coefficient in the current block (transform).

[106] The bitstream may include various information for image/video decoding, such as prediction information and the like, except for residual information including information regarding last_sig_coeff_x_prefix and last_sig_coeff_y_prefix as described above. As described above, the bit stream may be transmitted to the decoding equipment via a (digital) storage medium or a network.

[107] The decoding equipment may extract residual samples for the current block by performing a dequantization procedure and/or an inverse transform procedure based on the (quantized) transform coefficients. The reconstructed samples may be generated based on the residual samples and the predictive samples derived via inter/intra prediction, and a reconstructed frame including the reconstructed samples may be generated.

[108] FIG. 6 is a drawing for explaining high frequency nulling according to an example.

[109] In the present specification, "high-frequency nulling" means a process by which transform coefficients associated with a frequency equal to or greater than a certain value in a block (transform) having a first width (or length) dimension W ₁ and a first dimension H ₁ in height (or length) are set to zero (i.e. defined as zero). When high-frequency nulling is applied, transform coefficient values of transform coefficients outside the low-frequency transform coefficient region configured based on the second width dimension W ₂ and the second height dimension H ₂ of the transform coefficients in the block (transform) may be determined (set) as zero. The outer portion with respect to the low-frequency transform coefficient region may be referred to as the "high-frequency transform coefficient region". In an example, the area of low-frequency transform coefficients may be a rectangular area located at the upper left end of the block (transform).

[110] In the present description of the invention, a specific term or sentence is used to specify specific information or concepts. For example, in the present specification, as described above, a process by which transform coefficients associated with a frequency equal to or greater than a certain value in a block (transform) having a first width (or length) dimension W ₁ and a first dimension H ₁ height (or length), set as "high-frequency zeroing"; the region in which the nulling is performed through the high-frequency nulling is set as the "high-frequency transform coefficient region"; and a region for which zeroing is not performed is set as "a region of low-frequency transform coefficients". To represent the size of the low-frequency transform coefficient region, a second width dimension W ₂ (or length) and a second height dimension H ₂ (or length) are used.

[111] However, the term "high frequency nulling" may be replaced by various terms such as high frequency nulling, high frequency nulling, nulling, and the like; the term "high-frequency transform coefficient region" with various terms such as high-frequency nulling application region, high-frequency nulling region, high-frequency region, high-frequency coefficient region, high-frequency nulling region, nulling region, and the like; and the term "low-frequency transform coefficient region" by various terms such as a region without applying high-frequency nulling, a low-frequency region, a region of low-frequency coefficients, a limited region, and the like. Thus, in the present description of the invention, when interpreting throughout the detailed description of a particular term or sentence used to define a particular information or concept, it is necessary to pay attention to various operations, functions and advantages according to the content that the term should represent, and not be limited to its name.

[112] In an example, a method may be provided for performing binarization of the syntax elements, last_sig_coeff_x_prefix and last_sig_coeff_y_prefix, on a block (transformation) (TB, TU, or CB) to which high-frequency nulling is applied; last_sig_coeff_x_prefix and last_sig_coeff_y_prefix may be binarized with truncated Rice code, and at this time, the value of cRiceParam may use 0. The value of cMax used in binarization for truncated Rice code may be determined based on Equation 1 when performing binarization last_sig_coeff_x_prefix and be determined based on Equation 2 when binarizing last_sig_coeff_y_prefix.

[113] Equation 1

[114] cMax=(log2W _1< <1)-1

[115] Equation 2

[116] cMax=(log ₂ H _1< <1)-1,

[117] where W ₁ may represent the width (or width) of the box (transform) and H ₁ may represent the height (or height) of the box (transform). For example, in the case of a 64x32 transform block, as shown in FIG. 6, W ₁ is 64, and H ₁ is 32. Therefore, the last_sig_coeff_x_prefix binarization cMax value may be 11, and the last_sig_coeff_y_prefix binarization cMax value may be 9.

[118] Table 3 below represents binarization when W ₁ or H ₁ is 32, and Table 4 below represents binarization codeword when W ₁ or H ₁ is 64. In the example, binarization is truncated Rice code may be performed based on the transform block size, and because of this, as indicated in Table 4 below, the last_sig_coeff_x_prefix or last_sig_coeff_y_prefix codeword for encoding for a LastSignificantCoeffX or LastSignificantCoeffY value of 32-47 may be "11111111110", and the codeword last_sig_coeff_x_prefix or last_sig_coeff_y_prefix to encode for a LastSignificantCoeffX or LastSignificantCoeffY value of 48-63 may be "11111111111". In both cases, binarization can be performed based on 11 bins. The codeword may be referred to as a "string of permission elements".

[119] Tab. 3

[120] Tab. four

[121] As shown in Table 1 above, when the value of last_sig_coeff_x_prefix exceeds 3, last_sig_coeff_x_suffix may additionally be signaled, and LastSignificantCoeffX may be derived based on the value of last_sig_coeff_x_suffix. For example, the codeword last_sig_coeff_x_prefix to encode for a LastSignificantCoeffX value of 32-47 may be "11111111110", and which value of 32-47 is used may be determined based on the value of last_sig_coeff_x_suffix. As shown in Table 1 above, when the value of last_sig_coeff_y_prefix exceeds 3, last_sig_coeff_y_suffix may additionally be signaled, and LastSignificantCoeffY may be derived based on the value of last_sig_coeff_y_suffix. For example, the codeword last_sig_coeff_x_prefix to encode for a LastSignificantCoeffY value of 32-47 may be "11111111110", and which value of 32-47 is used may be determined based on the value of last_sig_coeff_y_suffix.

[122] A specific calculation for extracting LastSignificantCoeffX or LastSignificantCoeffY may be performed, for example, as follows.

[123] Tab. 5

The column position of the last significant coefficient in the scan order in the LastSignificantCoeffX block of the transform is retrieved as follows: // If last_sig_coeff_x_suffix is not present, the following applies: LastSignificantCoeffX=last_sig_coeff_x_prefix // Else (last_sig_coeff_x_suffix is present), the following applies: LastSignificantCoeffX=(1<<((last_sig_coeff_x_prefix> >1)-1))*(2+(last_sig_coeff_x_prefix&1))+last_sig_coeff_x_suffix // The row position of the last significant coeff in scan order in the LastSignificantCoeffY transform block is retrieved as follows: // If last_sig_coeff_y_suffix is not present, the following applies: LastSignificantCoeffY=last_sigcoeff_y_prefix // Otherwise (last_sig_coeff_y_suffix is present), the following applies: LastSignificantCoeffY=(1<<((last_sig_coeff_y_prefix>>1)-))*(2+(last_sig_c-oeff_y_prefix&1))+last_sig_coeff_y_suffix

[124] High-frequency zeroing means zeroing coefficients with a frequency greater than a certain value in a transform block having a first dimension W_one in width or first dimension H_one in height (i.e. defined as zero), and limiting the residual transform coefficients to the second dimension W₂ in width or second dimension H₂ in height. At this time, in an example, a method in which binarization is performed based on a truncated Rice code based on a size (a second width dimension or a second height dimension) of a restricted area extracted through high-frequency zeroing, rather than a method in which in which binarization is performed based on the truncated Rice code based on the size (first width dimension or first height dimension) of the conversion block. After setting cMax for last_sig_coeff_x_prefix and cMax for last_sig_coeff_y_prefix as Equations 3 and 4, respectively, using the second width dimension and the second height dimension, a truncated Rice code can be generated.

[125] Equation 3

[126] cMax=(log ₂ (min(W ₁ , W ₂ ))<<1)-1

[127] Equation 4

[128] cMax=(log ₂ (min(H ₁ , H ₂ ))<<1)-1

[129] In an example where the first width dimension or the first height dimension is 64 and the second width dimension or the second height dimension is 32, the truncated Rice code derived based on equations 3 and 4 may be as indicated in Table 6 below. Through the high-frequency nulling, the residual transform coefficient disappears from the high-frequency coefficients in the region of the high-frequency transform coefficients formed beyond the second width dimension or the second height dimension, so that it is possible to design the binarization codeword as indicated in Table 6 below.

[130] In an example, W ₂ and H ₂ may be set as a fixed value. Alternatively, W ₂ and H ₂ may be determined based on W ₁ and H ₁ . Alternatively, information indicating W ₂ and H ₂ may be signaled from the encoding equipment to the decoding equipment. In an example, W ₂ and H ₂ may be set to 32 or 16, respectively. In another example, W ₂ and H ₂ may be extracted as half W ₁ and half H ₁ , respectively. In yet another example, W ₂ and H ₂ may be extracted as half of max(W ₁ , H ₁ ). However, they are examples, and W ₂ and H ₂ may be determined according to various other methods defined in the encoding equipment and the decoding equipment. Through the proposed method, it is possible to effectively reduce the codeword length for some LastSignificantCoeffX or LastSignificantCoeffY values. Additionally, since the encoded bin reduced thereby is a context-encoded bin, an advantage in terms of throughput can be provided.

[131] Tab. 6

[132] In an example, the residual encoding method described above in FIG. 4A-5B may be based on the examples described in FIGS. 6. In another example, the encoding method which is described below in FIG. 7 or the decoding method as described below in FIG. 9 may be based on the examples described in FIG. 6.

[133] FIG. 7 is a flowchart showing the operation of the encoding equipment according to the example, and FIG. 8 is a block diagram showing a configuration of an encoding equipment according to an example.

[134] The encoding equipment of FIG. 7 and 8 can perform an operation corresponding to that of the decoding equipment of FIG. 9 and 10. Therefore, the operations of the decoding equipment, which are described below in FIG. 9 and 10 are likely to apply to the encoding equipment of FIG. 7 and 8.

[135] Each of the steps disclosed in FIG. 7 may be performed by the encoding equipment 200 disclosed in FIG. 2. More specifically, S700 may be performed by the subtractor 231 disclosed in FIG. 2; S710 through converter 232 disclosed in FIG. 2; S720 through the quantizer 233 disclosed in FIG. 2; and S730 through the entropy encoder 240 disclosed in FIG. 2. Additionally, the operations of S700-S730 are based on a portion of the content described above in FIG. 4-6. Therefore, the explanation for the specific content duplicated with the content described above in FIG. 2 and 4-6 is omitted or given briefly.

[136] As shown in FIG. 8, the encoding equipment according to the example may include a subtractor 231, a transformer 232, a quantizer 233, and an entropy encoder 240. However, according to the circumstances, all of the components shown in FIG. 8 may not be essential components of the encoding equipment, and the encoding equipment may be implemented with more or fewer components relative to the number of components shown in FIG. eight.

[137] In the encoding equipment of the example, subtractor 231, converter 232, quantizer 233, and entropy encoder 240 may each be implemented on a separate chip, or at least two or more components may be implemented on a single chip.

[138] The encoding equipment according to the example may extract residual samples for the current block (S700). More specifically, the coding equipment subtractor 231 may extract residual samples for the current block.

[139] The encoding equipment according to the example may derive transform coefficients for the current block by transforming the residual samples for the current block (S710). More specifically, the coding equipment transform 232 may derive transform coefficients for the current block by transforming the residual samples for the current block.

[140] The encoding equipment according to the example can extract quantized transform coefficients from the transform coefficients based on a quantization process (S720). More specifically, the encoding equipment quantizer 233 may extract quantized transform coefficients from the transform coefficients based on a quantization process.

[141] The encoding equipment according to the example may encode residual information including information regarding quantized transform coefficients (S730). More specifically, the coding equipment encoder 240 may encode residual information including information regarding quantized transform coefficients.

[142] In an example, each of the transform coefficients for the current block may be associated with a high-frequency transform coefficient region consisting of a transform coefficient of 0, or with a low-frequency transform coefficient region including at least one significant transform coefficient.

[143] In an example, the residual information includes last significant coefficient prefix information and last significant coefficient suffix information regarding the position of the last non-zero transform coefficient among the transform coefficients for the current block.

[144] In an example, the position of the last non-zero transform coefficient may be based on a prefix codeword that represents the last significant coefficient prefix information and the last significant coefficient suffix information.

[145] In an example, the maximum length of the prefix codeword may be determined based on the size of the region of low-frequency transform coefficients.

[146] According to the encoding equipment and the operation method of the encoding equipment of FIG. 7 and 8, the encoding equipment may extract the residual samples for the current block (S700), extract the transform coefficients for the current block by transforming the residual samples for the current block (S710), extract the quantized transform coefficients from the transform coefficients based on the quantization process (S720), and encode residual information including information on quantized transform coefficients (S730), wherein each of the transform coefficients for the current block may be associated with a high-frequency transform coefficient region consisting of a transform coefficient of 0, or with a low-frequency transform coefficient region including, at least one significant transform coefficient, the residual information may include last significant coefficient prefix information and last significant coefficient suffix information regarding the position of the last non-zero coefficient and transforms from among the transform coefficients for the current block, the position of the last non-zero transform coefficient may be based on a prefix codeword that represents the prefix information of the last significant coefficient and the suffix information of the last significant coefficient, and the maximum length of the prefix codeword may be determined based on the size of the low frequency region. conversion coefficients. Thus, according to the present disclosure, when high-frequency nulling is applied by performing binarization on a syntax element based on the size of the high-frequency nulling region (more correctly, the region to which high-frequency nulling is not applied), it is possible to perform encoding more efficiently and improve CABAC throughput. by reducing the number of context-encoded permission elements.

[147] FIG. 9 is a flowchart showing the operation of the decoding equipment according to the example, and FIG. 10 is a block diagram showing a configuration of decoding equipment according to an example.

[148] Each of the steps disclosed in FIG. 9 may be performed by the decoding equipment 300 disclosed in FIG. 3. More specifically, S900 and S910 may be performed by the entropy decoder 310 disclosed in FIG. 3; S920 through the dequantizer 321 disclosed in FIG. 3; S930 through the inverse converter 322 disclosed in FIG. 3; and S940 through the adder 340 disclosed in FIG. 3. Additionally, the operations of S900-S940 are based on a portion of the content described above in FIG. 4-6. Therefore, the explanation for the specific content duplicated with the content described above in FIG. 3-6 is omitted or given briefly.

[149] As shown in FIG. 10, the decoding equipment according to the example may include an entropy decoder 310, a dequantizer 321, an inverse transform 322, and an adder 340. However, according to the circumstances, all of the components shown in FIG. 10 may not be essential components of the decoding equipment, and the decoding equipment may be implemented with more or fewer components relative to the number of components shown in FIG. ten.

[150] In the decoding equipment of the example, entropy decoder 310, dequantizer 321, inverse converter 322, and adder 340 may each be implemented by a separate chip, or at least two or more components may be implemented by a single chip.

[151] The decoding equipment according to an example may receive a bitstream including residual information (S900). More specifically, the entropy decoder 310 of the decoding equipment may receive a bit stream including residual information.

[152] The decoding equipment according to the example may derive quantized transform coefficients for the current block based on the residual information included in the bitstream (S910). More specifically, the entropy decoder 310 of the decoding equipment may derive a quantized transform coefficient for the current block based on the residual information included in the bitstream.

[153] The decoding equipment according to the example can extract transform coefficients from the quantized transform coefficients based on a dequantization process (S920). More specifically, the dequantizer 321 of the decoding equipment may extract transform coefficients from the quantized transform coefficients based on a dequantization process.

[154] The decoding equipment according to the example can extract residual samples for the current block by applying an inverse transform to the extracted transform coefficients (S920). More specifically, the inverse transform 322 of the decoding equipment may extract the residual samples for the current block by applying an inverse transform to the extracted transform coefficients.

[155] The decoding equipment according to the example may generate a reconstructed frame based on the residual sample for the current block (S940). More specifically, the adder 340 of the decoding equipment may generate a reconstructed frame based on the residual sample for the current block.

[156] In an example, the current block unit may be a transform block TB.

[157] In an example, each of the transform coefficients for the current block may be associated with a high-frequency transform coefficient region consisting of a transform coefficient of 0, or with a low-frequency transform coefficient region including at least one significant transform coefficient.

[158] In an example, the residual information may include last significant coefficient prefix information and last significant coefficient suffix information regarding the position of the last non-zero transform coefficient among the transform coefficients for the current block.

[159] In an example, the position of the last non-zero transform coefficient may be determined based on a prefix codeword that represents the last significant coefficient prefix information and the last significant coefficient suffix information.

[160] In an example, the maximum length of the prefix codeword may be determined based on the size of the region of low-frequency transform coefficients. The maximum length of the prefix codeword may be expressed as cMax.

[161] In an example, the size of the low-frequency transform coefficient region may be determined based on the width and height of the low-frequency transform coefficient region.

[162] In an example, the prefix information of the last significant coefficient may include the X-axis prefix information and the Y-axis prefix information, and the prefix codeword may be a codeword for the X-axis prefix information or a codeword for the X-axis prefix information. Y.

[163] In an example, the x-axis prefix information may be expressed as last_sig_coeff_x_prefix; the y-axis prefix information may be expressed as last_sig_coeff_y_prefix; and the position of the last non-zero transform coefficient may be expressed as (LastSignificantCoeffX, LastSignificantCoeffY).

[164] In an example, the maximum length of a codeword that indicates prefix information on the x-axis may be determined to be 9 based on determining that the width of the low-frequency transform coefficient region is 32.

[165] In an example, the maximum length of a codeword that indicates prefix information along the Y-axis may be determined to be 9 based on determining that the height of the low-frequency transform coefficient region is 32.

[166] In an example, the maximum binarized codeword value for the X-axis prefix information may be determined to be 111111111 based on determining that the width of the current block is greater than 32 and that the width of the low-frequency transform coefficient region is 32.

[167] In an example, the maximum binarized codeword value for the Y-axis prefix information may be determined to be 111111111 based on determining that the height of the current block is greater than 32 and that the height of the low-frequency transform coefficient region is 32.

[168] In an example, the maximum codeword length for X-axis prefix information may be determined based on Equation 5 below.

[169] Equation 5

[170] cMax _x =(log ₂ (min(W ₁ , W ₂ ))<<1)-1

[171] In Equation 5, cMax _x may be the maximum codeword length for X-axis prefix information; W ₁ may be the width of the current block; and W ₂ may be the width of the region of the low-frequency transform coefficients.

[172] In the example, the width of the region of low-frequency transform coefficients may be equal to 32, and the maximum codeword length for X-axis prefix information may be determined based on Equation 6 below.

[173] Equation 6

[174] cMax _x =(min(log ₂ W ₁ , 5))<<1)-1

[175] In Equation 6, cMax _x may be the maximum codeword length for X-axis prefix information, and W ₁ may be the width of the current block.

[176] In an example, the maximum codeword length for the Y-axis prefix information may be determined based on Equation 7 below.

[177] Equation 7

[178] cMax _y =(log ₂ (min(H ₁ , H ₂ ))<<1)-1

[179] In Equation 7, cMax _y may be the maximum codeword length for the Y-axis prefix information; H ₁ can be the height of the current block; and H ₂ may be the height of the region of low-frequency transform coefficients.

[180] In the example, the height of the low-frequency transform coefficient region may be 32, and the maximum codeword length for the Y-axis prefix information may be determined based on Equation 8 below.

[181] Equation 8

[182] cMax _y =(min(log ₂ H ₁ , 5))<<1)-1

[183] In Equation 8, cMax _y may be the maximum codeword length for X-axis prefix information, and H ₁ may be the height of the current block.

[184] In an example, the prefix codeword may be a truncated Rice code based on a truncated Rice code binarization process.

[185] In an example, the current block may be a square block or a non-square block. The width of the low pass transform coefficient region may be determined to be 32 based on determining that the current block width is 64, and the height of the low pass transform coefficient region may be determined to be 32 based on determining that the current block height is 64.

[186] In an example, the size of the low-frequency transform coefficient region may be one of 32×16, 16×32, 16×16, or 32×32.

[187] In an example, the size of the region of low-frequency transform coefficients may be determined based on the size of the current block.

[188] In an example, the residual information may include information regarding the size of the region of low-frequency transform coefficients.

[189] In the example, the size of the current block may be 64×64; the size of the region of low-frequency transform coefficients may be 32×32; and the maximum length of the prefix codeword may be 9.

[190] According to the decoding equipment and the operation method of the decoding equipment of FIG. 9 and 10, the decoding equipment may receive a bitstream including the residual information (S900), extract quantized transform coefficients for the current block based on the residual information included in the bitstream (S910), extract transform coefficients from the quantized transform coefficients based on a process dequantizing (S920), and extracting the residual samples for the current block by applying an inverse transform to the extracted transform coefficients (S930), and generating a reconstructed frame based on the residual samples for the current block (S940), wherein each of the transform coefficients for the current block can be associated with a high-frequency transform coefficient region consisting of a transform coefficient of 0, or with a low-frequency transform coefficient region including at least one significant transform coefficient, the residual information may include prefix information n last significant coefficient and last significant coefficient suffix information regarding the position of the last non-zero transform coefficient among the transform coefficients for the current block, the position of the last non-zero transform coefficient may be determined based on a prefix codeword that represents the last significant coefficient prefix information and the last significant coefficient suffix information, and the maximum length of the prefix codeword may be determined based on the size of the region of the low-frequency transform coefficients. Thus, according to the present disclosure, when high-frequency nulling is applied by performing binarization on a syntax element based on the size of the high-frequency nulling region (more correctly, the region to which high-frequency nulling is not applied), it is possible to perform encoding more efficiently and improve CABAC throughput. by reducing the number of context-encoded permission elements.

[191] In an example, the residual encoding process described above in FIG. 4-10 may be based on the contents of the English detailed description below.

[192] ABSTRACT

[193] In this proposal, the binarization of the position of the last significant coefficient is modified to reduce the maximum number of context-encoded bins. In particular, the number of context-coded bins for a large block (i.e. 64x64, 64xN, Nx64) in the worst-case scenario is reduced from 11 to 9. Experimental results show 0.01%, 0%- e and -0.02% reduction in BD-factor for components Y, Cb and Cr, respectively, compared to VTM3.0 in a fully internal configuration, and 0.01%-e, -0.01%- and - 0.01% reduction in BD ratio in random access configuration.

[194] 1. Introduction

[195] It is known that more block segmentation typically represents fewer residues, and the energy is more concentrated in the low frequency coefficients in the transform region. In VTM3.0 [1], high-frequency transform coefficients are reduced to zero for transform blocks with a size (width or height, or both width and height) equal to 64. Thus, for a WxH transform block, where W indicates the width of the block and H specifies the block height, only the top left (W==64?32:W)x(H==64?32:H) of the transform coefficients are kept.

[196] In [1], the prefix last_sig_coeff_x_prefix and last_sig_coeff_y_prefix are context-encoded using truncated Rice binarization with cMax=(log2TbSize<<1)-1. Here, if the syntax element to be parsed is last_sig_coeff_x_prefix, log2TbSize is set to log2TbWidth and otherwise, log2TbSize is set to log2TbHeight. Thus, the maximum possible absolute value is determined by the width or height of the transform block. In the worst-case scenario, the number of bins that use context modeling is 11. Table 7 shows the binarization for W=64 or H=64 in VTM3.0, with X meaning 0 or 1.

[197] Tab. 7

[198] 2. The proposed method

[199] This work is proposed in addition to JVET-M0250 [2]. In the proposed method, it is checked whether or not the current group of coefficients belongs to the high-frequency zeroing region. When using this information, optional coding based on the coded_sub_block_flag (CSBF) for the high frequency nulling region can be skipped.

[200] In one embodiment, a CSBF coding method considering a high frequency nulling region may be provided. If the first condition for the last or first coefficient group is satisfied, the CSBF value may be inferred to be 1. If the first condition for the last or first coefficient group is not satisfied, the second condition for the high frequency null region is checked. If the second condition for the high frequency nulling region is satisfied, no CSBF encoding is performed. If the second condition for high frequency nulling is not satisfied, the context index is retrieved and CSBF encoding is performed.

[201] The last position coding scheme is proposed for conversion with large block sizes. Compared to VTM3.0, the proposed encoding scheme uses fewer context-encoded bins in a worst-case scenario. The code word in the proposed scheme still begins with a truncated Rice code, followed by a fixed length code. After high-frequency zeroing, for the WxH transform block, only the upper left min(W, 32)xmin(H, 32) of the transform coefficients are stored. Thus, the maximum possible length of last_sig_coeff_x_prefix or last_sig_coeff_y_prefix prefix codewords is extracted as:

[202] cMax=(min(log ₂ TbSize, 5)<<1)-1.

[203] Table 8 shows the binarization for W=64 or H=64, with X meaning 0 or 1. Here, various parts are underlined.

[204] Tab. eight

[205] Tab. 9

[206] Table 9 shows a comparison of the length of prefix codewords (context-encoded bins) when W=64 or H=64 and VTM3.0. Context-encoded permission elements may be present up to 9 in the proposed method, while up to 11 permission elements are provided in VTM3.0. It should be noted that when the absolute value of the last position component is in the range of 24-31, the number of context-coded bins is reduced from 10 to 9.

[207] 3. Experimental results

[208] The proposed method is implemented in the VTM3.0 software. Simulations are performed according to the general test conditions specified in JVET-L1010 [3]. In each case, the binding is the VTM3.0 software. Encoding time and decoding time come from the results of cross-validation [4]. Table 10 shows the experimental results for the test condition for all indoor (AI) mode; the binding is VTM3.0.

[209] Tab. ten

Fully internal mode, profile Main10 Based on VTM3.0 Y U V Enct DecT Class A1 0.03% -0.07% 0.03% 100% 101% Class A2 0.02% 0.00% -0.03% 100% 100% Class B 0.01% 0.05% -0.02% 100% 102% Class C 0.00% 0.01% -0.03% 100% 101% Class E 0.02% -0.02% -0.03% 100% 99% Total 0.01% 0.00% -0.02% 100% 101% Class D 0.00% 0.01% -0.01% 100% 100% Class F -0.01% 0.03% 0.02% 100% 99%

[210] Table 11 shows the experimental results for the test condition for the random access (RA) mode; the binding is VTM3.0.

[211] Tab. eleven

Random access mode, profile Main10 Based on VTM3.0 Y U V Enct DecT Class A1 0.05% -0.09% 0.00% Class A2 0.01% 0.07% 0.03% Class B -0.01% -0.02% -0.04% 100% 100% Class C 0.00% 0.02% -0.01% 99% 100% Class E Total 0.01% -0.01% -0.01% Class D 0.00% 0.03% 0.06% 100% 100% Class F -0.01% -0.03% -0.07% 100% 99%

[212] 4. References

[213] [1] B. Bross et al. "Versatile Video Coding (Draft 3)", Joint Video Exploration Team (JVET) of ITU-T SG 16 WP 3 and ISO/IEC JTC1/SC 29/WG 11 JVET- L1001, 12th Conference, Macau, China, October 3-12, 2018.

[214] [2] J. Choi et al. "Non-CE7: Simplified CSBF coding for large block-size transforms", Joint Video Exploration Team (JVET) of ITU-T SG 16 WP 3 and ISO/IEC JTC1/SC 29/WG 11 JVET-M0250, 13th Conference, Marrakech, Morocco, January 9-18, 2019.

[215] [3] F. Bossen et al. "JVET common test conditions and software reference configurations for SDR video" Joint Video Exploration Team (JVET) of ITU-T SG 16 WP 3 and ISO/IEC JTC1/SC 29/WG 11 JVET-L1010, 12th Conference, Macau, China, October 3-12, 2018.

[216] [4] H. Schwarz "Crosscheck of JVET-M0251 (Non-CE7: Last position coding for large block-size transforms)", Joint Video Exploration Team (JVET) of ITU-T SG 16 WP 3 and ISO/ IEC JTC1/SC 29/WG 11 JVET-M0646, 13th Conference, Marrakesh, Morocco, January 9-18, 2019.

[217] 5. Patent Rights Statement

[218] LG Electronics Inc. may have current or pending patent rights related to the technology described in this work, and in accordance with the principle of reciprocity, is ready to grant licenses under reasonable and non-discriminatory conditions, if necessary, to implement the resulting ITU-T/ISO/IEC International Standard recommendation (according to section 2 of the ITU-T/ITU-R/ISO/IEC patent application and the license declaration form).

[219] 6. Specification

[220] Tab. 12

[221] last_sig_coeff_x_prefix indicates the prefix of the column position of the last significant coefficient in the scan order in the transform block. Last_sig_coeff_x_prefix values must be between 0 and (Min(log ₂ TbWidth, 5)<<1)-1, inclusive.

[222] last_sig_coeff_y_prefix indicates the prefix of the row position of the last significant coefficient in the scan order in the transform block. Last_sig_coeff_y_prefix values must be between 0 and (Min(log ₂ TbHeight, 5)<<1)-1, inclusive.

[223] Table 13 below shows the syntax elements and associated binarizations.

[224] Tab. 13

[225]

[226]

[227]

[228]

[229] In the above example, the methods are explained based on the flowchart by means of a sequence of steps or blocks, but the present disclosure is not limited to the order of the steps, and a certain step may occur in a different order or simultaneously with steps other than the steps described above. . Additionally, those skilled in the art will appreciate that the steps shown in the flowchart are not the only ones possible, and that another step may be included, or one or more steps in the flowchart may be removed without affecting scope of this disclosure.

[230] The above methods according to the disclosure may be implemented in software form, and the encoding equipment and/or decoding equipment according to the disclosure may be included in equipment to perform image processing, such as a TV, computer, smartphone, set-top box, and display device.

[231] In the disclosure, when the examples are implemented by software, the above methods can be implemented using modules (process, function, etc.) to perform the above functions. The modules may be stored in a storage device and may be executed by a processor. The storage device may be located inside or outside the processor and may be connected to the processor through various known means. The processor may include an application specific integrated circuit (ASIC), various chipsets, logic, and/or a data processor. The storage device may include Read Only Memory (ROM), Random Access Memory (RAM), flash memory, a memory card, storage media, and/or other storage device. Thus, the examples described in this disclosure may be implemented and executed in a processor, microprocessor, controller, or chip. For example, the functional modules shown in each figure may be implemented and executed in a processor, microprocessor, controller, or chip. In this case, the information or algorithm to be implemented (eg, information regarding the instruction) may be stored in the digital storage medium.

[232] Additionally, the decoding equipment and encoding equipment to which the present disclosure applies may be included in a broadcast multimedia transceiver, a mobile communication terminal, a home theater system video device, a digital cinema system video device, a surveillance camera, a video chat device, a communication device real-time, such as video communication, mobile streaming device, storage media, video recording camera, video-on-demand (VoD) service provider, video device over networks (OTT), Internet streaming service provider , a 3D video device, a virtual reality style device, an augmented reality (augmented reality) style device, a video telephony system video device, a terminal in a vehicle (for example, a terminal in a vehicle (including an autonomous vehicle). equipment), an aircraft terminal, a ship terminal, etc.) and a medical video device, and can be used to process a video signal or a data signal. For example, a video over network (OTT) device may include a game console, a Blu-ray player, an Internet access TV, a home theater system, a smartphone, a tablet PC, a digital video recorder (DVR), and the like.

[233] In addition, the processing method to which the present disclosure applies may be formed in the form of a program executable by a computer and stored in a computer-readable recording medium. Multimedia data having a data structure according to the present disclosure may also be stored on a computer-readable recording medium. The computer-readable recording medium includes all kinds of storage devices and distributed storage devices that store computer-readable data. The computer-readable recording medium may include, for example, a Blu-ray Disc (BD), Universal Serial Bus (USB), ROM, PROM, EPROM, EEPROM, RAM, CD-ROM, magnetic tape, floppy disk, and optical storage. . Additionally, the computer-readable recording medium also includes media implemented in the form of a carrier wave (eg, transmission over the Internet). In addition, the bitstream generated by the encoding method may be stored in a computer-readable recording medium or transmitted via a wired or wireless communication network.

[234] Additionally, examples of the present disclosure may be implemented as a computer program product by means of program codes, and the program codes may be executed on a computer by means of the examples of this disclosure. The program codes may be stored on a computer-readable medium; steps other than those described above. Additionally, it will be apparent to those skilled in the art that the steps shown in the flowchart are not the only ones possible, and that:

[235] FIG. 11 represents an example of a content streaming system to which the disclosure of this document may apply.

[236] Referring to FIG. 11, the content streaming system to which the embodiment(s) of the present document is applied may mainly include an encoding server, a streaming server, a web server, a media storage, a user device, and a media input device.

[237] The encoding server compresses content input from media input devices such as a smartphone, a camera, a camcorder, etc. into digital data in order to generate a bit stream and transmit the bit stream to the stream server. As another example, when media input devices such as smartphones, cameras, camcorder recorders, etc. directly generate a bitstream, the encoding server may be omitted.

[238] The bit stream may be generated by the encoding method or the bit stream generation method to which the embodiment(s) of the present document is applied, and the stream server may temporarily store the bit stream in the process of transmitting or receiving the bit stream.

[239] The streaming server transmits media data to the user device based on the user's request through the web server, and the web server serves as a medium for informing the user about the service. When a user requests a desired service from a web server, the web server delivers it to the streaming server, and the streaming server transmits media data to the user. In this case, the content streaming system may include a separate control server. In this case, the control server serves to manage the command/response between devices in the content streaming system.

[240] The streaming server may receive content from a media store and/or an encoding server. For example, when content is received from an encoding server, the content may be received in real time. In this case, in order to provide a smooth streaming service, the streaming server may keep the bitstream for a predetermined time.

[241] Examples of the user device may include a mobile phone, smartphone, laptop computer, digital broadcast terminal, personal digital assistant (PDA), portable media player (PMP), navigation device, stylus tablet PC, tablet PCs, ultrabooks, wearable devices (e.g., smart watches, smart glasses, head-mounted displays), digital TVs, desktop computers, digital signage system, etc. Each server in the content streaming system may operate as a distributed server, in which case the data received from each server may be distributed.

[242] Each of the servers in the content streaming system can operate as a distributed server, in which case, data received by each server can be distributed processed.

Claims (55)

1. An image decoding method performed by decoding equipment, the method comprising the steps of: receiving a bit stream including the residual information; obtaining transform coefficients for the current block based on the residual information; obtaining residual discrete samples for the current block by applying an inverse transform to the obtained transform coefficients; and a reconstructed frame is formed on the basis of residual discrete samples for the current block, while the current block includes a low-frequency transform coefficient region including at least one significant transform coefficient, and a region other than the low-frequency transform coefficient region including a zero transform coefficient, the residual information includes last significant coefficient prefix information and last significant coefficient suffix information regarding the position of the last non-zero transform coefficient among the transform coefficients for the current block, the position of the last non-zero transform coefficient is determined based on the prefix codeword and the suffix information of the last significant coefficient, wherein the prefix codeword is associated with the prefix information of the last significant coefficient, and the maximum length of the prefix codeword is determined based on the size of the region of low-frequency transform coefficients. 2. The image decoding method of claim 1, wherein the size of the low pass transform coefficient region is determined based on the width and height of the low pass transform coefficient region, and the last significant coefficient prefix information includes X-axis prefix information and Y-axis prefix information, and the prefix codeword is a codeword for the x-axis prefix information or a codeword for the y-axis prefix information. 3. The image decoding method according to claim 2, wherein the maximum length of a codeword that indicates prefix information along the X-axis is determined to be 9 based on the width of the region of low-frequency transform coefficients of 32, and the maximum length of a codeword that indicates prefix information on the Y-axis is determined to be 9 based on the height of the low-frequency transform coefficient region of 32. 4. The image decoding method of claim 3, wherein the maximum binarized codeword value for the X-axis prefix information is determined to be 111111111 based on a current block width greater than 32 and a low-pass transform coefficient region width of 32, and the maximum binarized codeword value for the Y-axis prefix information is determined to be 111111111 based on the height of the current block being greater than 32 and the height of the low-frequency transform coefficient region being 32. 5. The image decoding method according to claim 2, wherein the maximum codeword length for the x-axis prefix information is determined based on cMax _x , cMax _{x is} calculated based on the following equation: cMax _x =(log ₂ (min(W ₁ , W ₂ ))<<1)-1, where cMax _x is equal to the maximum codeword length for the X-axis prefix information, W ₁ is the width of the current block, and W ₂ is the width of the region of the low-frequency transform coefficients. 6. The image decoding method according to claim 5, wherein the width of the region of low-frequency transform coefficients is 32, and the maximum codeword length for the X-axis prefix information is determined based on cMax _x , wherein cMax _{x is} calculated based on the following equation: cMax _x =(min(log ₂ W ₁ , 5))<<1)-1, where cMax _x is equal to the maximum codeword length for x-axis prefix information, and W ₁ is the width of the current block. 7. The image decoding method according to claim 2, wherein the maximum codeword length for the Y-axis prefix information is determined based on cMax _y , wherein cMax _y is calculated based on the following equation: cMax _y =(log ₂ (min(H ₁ , H ₂ ))<<1)-1, where cMax _y is equal to the maximum codeword length for the y-axis prefix information, H ₁ is the height of the current block, and H ₂ is the height of the low-frequency transform coefficient region. 8. The image decoding method according to claim 7, wherein the height of the low-frequency transform coefficient region is 32, and the maximum codeword length for the Y-axis prefix information is determined based on Max _y , cMax _y is calculated based on the following equation: cMax _y =(min(log ₂ H ₁ , 5))<<1)-1, where cMax _y is equal to the maximum codeword length for prefix information along the y-axis, and H ₁ is the height of the current block. 9. The image decoding method according to claim 1, wherein the current block is a square block or a non-square block, the width of the region of low-frequency transform coefficients is determined to be 32 based on the current block width of 64, and the height of the low-frequency transform coefficient region is determined to be 32 based on the height of the current block being 64. 10. The image decoding method according to claim 1, wherein the size of the low-frequency transform coefficient region is one of 32˟16, 16˟32, 16˟16, and 32˟32. 11. The image decoding method of claim 1, wherein the size of the low-frequency transform coefficient region is determined based on the size of the current block. 12. The image decoding method according to claim 1, wherein the residual information includes information regarding the size of the low-frequency transform coefficient region. 13. The image decoding method according to claim 1, wherein the current block size is 64˟64, the size of the low-frequency transform coefficient region is 32˟32, and the maximum prefix codeword length is 9. 14. An image encoding method performed by encoding equipment, the method comprising the steps of: getting residual discrete samples for the current block; obtaining transform coefficients for the current block based on the residual discrete samples for the current block; and encode the residual information associated with the transformation coefficients, while the current block includes a low-frequency transform coefficient region including at least one significant transform coefficient, and a region other than the low-frequency transform coefficient region including a zero transform coefficient, the residual information includes last significant coefficient prefix information and last significant coefficient suffix information regarding the position of the last non-zero transform coefficient among the transform coefficients for the current block, the position of the last non-zero transform coefficient is based on the prefix codeword and the suffix information of the last significant coefficient, wherein the prefix codeword is associated with the prefix information of the last significant coefficient, and the maximum length of the prefix codeword is determined based on the size of the region of low-frequency transform coefficients. 15. A non-volatile computer-readable storage medium that stores instructions that, when executed by a computing device, instruct the computing device to carry out a method for generating a bit stream, the method comprising: obtaining residual discrete readings for the current block; obtaining transform coefficients for the current block based on the residual discrete samples for the current block; encoding the residual information associated with the transform coefficients to form a bitstream, wherein the current block includes a low-frequency transform coefficient region including at least one significant transform coefficient, and a region other than the low-frequency transform coefficient region including a zero transform coefficient, the residual information includes last significant coefficient prefix information and last significant coefficient suffix information regarding the position of the last non-zero transform coefficient among the transform coefficients for the current block, the position of the last non-zero transform coefficient is based on the prefix codeword and the suffix information of the last significant coefficient, wherein the prefix codeword is associated with the prefix information of the last significant coefficient, and the maximum length of the prefix codeword is determined based on the size of the region of low-frequency transform coefficients. 16. A method for transmitting data for image information, comprising the steps of: obtaining an image information bitstream including residual information, wherein the residual information is generated by obtaining residual discrete samples for the current block, obtaining transform coefficients for the current block based on the residual discrete samples for the current block, and encoding the residual information associated with the transform coefficients, to form a bitstream; and transmitting data containing an image information bit stream including residual information, wherein the current block includes a low-frequency transform coefficient region including at least one significant transform coefficient, and a region other than the low-frequency transform coefficient region including a zero transform coefficient, the residual information includes last significant coefficient prefix information and last significant coefficient suffix information regarding the position of the last non-zero transform coefficient among the transform coefficients for the current block, the position of the last non-zero transform coefficient is based on the prefix codeword and the suffix information of the last significant coefficient, wherein the prefix codeword is associated with the prefix information of the last significant coefficient, and the maximum length of the prefix codeword is determined based on the size of the region of low-frequency transform coefficients.

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