Signaling based picture or video coding of transform skip and palette coding related information

Abstract

The present invention relates to image or video coding based on signaling of transform skip and palette coding related information.SOLUTION: According to the disclosure of the present document, transform skip availability information and palette availability information may be signaled through a SequenceParameterSet (SPS), and transform skip and / or palette coding related information may be effectively parsed / signaled based on at least one of the transform skip availability information and the palette availability information. Accordingly, bits to be signaled for video / image coding can be saved and coding efficiency can be improved.SELECTED DRAWING: Figure 12

Description

[Technical Field]

[0001] The present technology relates to video or image coding, for example, to signaling-based image or video coding techniques for transform skip and palette coding related information. [Background technology]

[0002] In recent years, demand for high-resolution, high-quality images / videos, such as 4K or 8K or higher UHD (Ultra High Definition) images / videos, has been increasing in various fields. As the resolution and quality of image / video data increases, the amount of information or bits to be transmitted increases relatively compared to existing image / video data. Therefore, when transmitting image data using existing media such as wired or wireless broadband lines or storing image / video data using existing storage media, transmission costs and storage costs increase.

[0003] In addition, interest and demand for immersive media such as VR (Virtual Reality), AR (Artificial Reality) content and holograms has been increasing in recent years, and the broadcast of images / videos with image characteristics different from real images, such as images, has been increasing.

[0004] Therefore, there is a need for highly efficient image / video compression technology to effectively compress and transmit, store, and play back high-resolution, high-quality image / video information having the above-mentioned various characteristics.

[0005] In addition, a method is needed to improve the overall efficiency of image / video coding by efficiently determining whether to code related information depending on the dependency and non-terminal attributes of information that is essential or used auxiliary in performing transform skip and palette coding. Summary of the Invention [Problem to be solved by the invention]

[0006] The technical problem of this document is to provide a method and apparatus for improving video / image coding efficiency.

[0007] Another technical problem of this document is to provide a method and apparatus for efficiently parsing / signaling transform skip and / or palette coding related information.

[0008] Another technical object of the present invention is to provide a method and apparatus for efficiently determining whether to perform coding depending on the dependency and / or non-terminal attribute of information used in transform skip and / or palette coding.

[0009] Another technical problem of this document is to provide a method and apparatus for defining a dependency condition for effectively parsing a syntax element that is dependent on a high-level syntax element related to transform skipping and / or palette coding, and for determining whether to perform parsing based on the dependency condition. [Means for solving the problem]

[0010] According to an embodiment of the present document, transform skip availability information and palette availability information are signaled via a Sequence Parameter Set (SPS), and it is possible to determine whether to parse / signal minimum quantization parameter information regarding a minimum allowed quantization parameter for a transform skip mode based on at least one of the transform skip availability information and the palette availability information. For example, the minimum quantization parameter information may be parsed / signaled in the SPS based on a condition that the value of the transform skip availability information is 1 or the value of the palette coding availability information is 1.

[0011] According to an embodiment of the present document, there is provided a video / image decoding method performed by a decoding device, the video / image decoding method including the methods disclosed in the embodiments of the present document.

[0012] According to an embodiment of the present document, there is provided a decoding device for performing video / image decoding, the decoding device performing the method disclosed in the embodiment of the present document.

[0013] According to an embodiment of the present document, there is provided a video / image encoding method performed by an encoding device, which includes the methods disclosed in the embodiments of the present document.

[0014] According to an embodiment of the present document, there is provided an encoding device for performing video / image encoding, which performs the method disclosed in the embodiment of the present document.

[0015] According to one embodiment of the present document, a computer-readable digital storage medium is provided that stores encoded video / image information generated by the video / image encoding method disclosed in at least one of the embodiments of the present document.

[0016] According to one embodiment of the present document, a computer-readable digital storage medium is provided that stores encoded information or encoded video / image information that enables a decoding device to perform the video / image decoding method disclosed in at least one of the embodiments of the present document. [Effects of the Invention]

[0017] This document may have various advantages. For example, according to an embodiment of this document, overall image / video compression efficiency may be improved. According to an embodiment of this document, information related to transform skip and / or palette coding may be efficiently parsed / signaled. According to an embodiment of this document, whether to code information used in transform skip and / or palette coding may be effectively determined based on its dependency and / or non-terminal attributes. According to an embodiment of this document, a dependency condition for effectively parsing a syntax element that is dependent on a high-level syntax element related to transform skip and / or palette coding may be defined, and whether to parse the element may be determined based on the dependency condition, thereby enabling efficient coding. According to an embodiment of this document, whether to parse a high-level syntax element related to transform skip and / or palette coding may be determined based on the dependency condition, thereby saving transmitted bits.

[0018] The effects that can be obtained through a specific example of this document are not limited to the effects listed above. For example, there may be various technical effects that a person having ordinary skill in the related art can understand or derive from this document. Therefore, the specific effects of this document are not limited to those explicitly described in this document, but may include various effects that can be understood or derive from the technical features of this document. [Brief explanation of the drawings]

[0019] [Figure 1] 1 illustrates a schematic diagram of an example video / image coding system that can be applied to embodiments of the present document. [Figure 2]1 is a diagram illustrating the configuration of a video / image encoding device to which an embodiment of this document can be applied. [Figure 3] 1 is a diagram illustrating the configuration of a video / image decoding device to which an embodiment of this document can be applied. [Figure 4] 1 shows an example of a general video / image encoding method to which the embodiments of this document can be applied. [Figure 5] 1 shows an example of a general video / image decoding method to which the embodiments of this document can be applied. [Figure 6] 1 illustrates a schematic diagram of an example of an entropy encoding method to which embodiments of the present document can be applied. [Figure 7] 1 illustrates a schematic diagram of an entropy encoding unit in an encoding device. [Figure 8] 1 illustrates a schematic diagram of an example of an entropy decoding method to which embodiments of the present document can be applied. [Figure 9] 1 illustrates a schematic diagram of an entropy decoding unit in a decoding device. [Figure 10] 1 illustrates an example of a video / image encoding method and associated components according to embodiment(s) of the present document; [Figure 11] 1 illustrates an example of a video / image encoding method and associated components according to embodiment(s) of the present document; [Figure 12] 1 illustrates an example of a video / image decoding method and associated components according to embodiment(s) of the present document; [Figure 13] 1 illustrates an example of a video / image decoding method and associated components according to embodiment(s) of the present document; [Figure 14] 1 illustrates an example of a content streaming system to which the embodiments disclosed herein may be applied. DETAILED DESCRIPTION OF THE INVENTION

[0020] This document may be modified in various ways and may have various embodiments. Specific embodiments will be illustrated in the drawings and described in detail. However, this is not intended to limit this document to the specific embodiments. Common terms used in this document are used merely to describe specific embodiments and are not intended to limit the technical ideas of this document. A singular expression includes a plural expression unless the context clearly dictates otherwise. In this specification, the terms "comprise" or "have" are intended to specify the presence of a feature, number, step, operation, component, part, or combination thereof described in the specification, and should be understood not to preclude the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0021] Meanwhile, each component in the drawings described in this document is illustrated independently for the convenience of explaining the different characteristic functions, and does not mean that each component is realized by separate hardware or software. For example, two or more components may be combined to form a single component, or a single component may be divided into multiple components. Embodiments in which each component is integrated and / or separated are also included within the scope of this document as long as they do not deviate from the essence of this document.

[0022] In this document, "A or B" can mean "only A," "only B," or "both A and B." In other words, in this document, "A or B" can be interpreted as "A and / or B." For example, in this specification, "A, B or C" can mean "only A," "only B," "only C," or "any combination of A, B, and C."

[0023] As used herein, a slash ( / ) or a comma can mean "and / or." For example, "A / B" can mean "A and / or B." Thus, "A / B" can mean "only A," "only B," or "both A and B." For example, "A, B, C" can mean "A, B, or C."

[0024] As used herein, "at least one of A and B" can mean "only A," "only B," or "both A and B." Furthermore, as used herein, the expressions "at least one of A or B" and "at least one of A and / or B" can be interpreted as "at least one of A and B."

[0025] Furthermore, in this specification, "at least one of A, B, and C" can mean "only A," "only B," "only C," or "any combination of A, B, and C." Furthermore, "at least one of A, B, or C" or "at least one of A, B, and / or C" can mean "at least one of A, B, and C."

[0026] Furthermore, parentheses used herein may mean "for example." Specifically, when "prediction (intra prediction)" is used, "intra prediction" may be suggested as an example of "prediction." In other words, "prediction" in this specification is not limited to "intra prediction," and "intra prediction" may be suggested as an example of "prediction." Furthermore, when "prediction (i.e., intra prediction)" is used, "intra prediction" may be suggested as an example of "prediction."

[0027] This document relates to video / image coding. For example, the methods / embodiments disclosed in this document may be applied to methods disclosed in the versatile video coding (VVC) standard. Also, the methods / embodiments disclosed in this document may be applied to methods disclosed in the essential video coding (EVC) standard, the AOMedia Video 1 (AV1) standard, the second generation audio video coding standard (AVS2), or next-generation video / image coding standards (e.g., H.267 or H.268).

[0028] This document presents various embodiments relating to video / image coding, and unless otherwise stated, the embodiments may be implemented in combination with each other.

[0029] In this document, video may refer to a collection of a series of images over time. A picture generally refers to a unit that shows one image at a specific time, and a slice / tile is a unit that constitutes part of a picture in coding. A slice / tile may include one or more coding tree units (CTUs). A picture may be composed of one or more slices / tiles. A picture may be composed of one or more tile groups. A tile is a rectangular region of CTUs within a particular tile column and a particular tile row in a picture. The tile column is a rectangular region of CTUs, and the rectangular region has a height equal to the height of the picture and a width specified by syntax elements in the picture parameter set. The tile row is a rectangular region of CTUs having a height specified by syntax elements in the picture parameter set and a width equal to the width of the picture.A tile scan indicates a specific sequential ordering of CTUs partitioning a picture in which the CTUs are ordered consecutively in CTU raster scan in a tile, whereas tiles in a picture are ordered consecutively in a raster scan of the tiles of the picture. A slice includes an integer number of complete tiles or an integer number of consecutive complete CTU rows within a tile of a picture that may be exclusively contained in a single NAL unit.

[0030] On the other hand, a picture is divided into two or more sub-pictures, each of which is a rectangular region of one or more slices within a picture.

[0031] A pixel or a pel may refer to the smallest unit constituting a picture (or image). A "sample" may also be used as a term corresponding to a pixel. A sample may generally refer to a pixel or a pixel value, may refer to only a pixel / pixel value of a luma component, or may refer to only a pixel / pixel value of a chroma component. Alternatively, a sample may refer to a pixel value in the spatial domain, or, when such a pixel value is transformed into the frequency domain, may refer to a transform coefficient in the frequency domain.

[0032] A unit may refer to a basic unit of image processing. A unit may include at least one of a specific region of a picture and information related to the region. One unit may include one luma block and two chroma (e.g., cb, cr) blocks. The term unit may be used interchangeably with terms such as block or area. In general, an M×N block may include samples (or a sample array) consisting of M columns and N rows, or a set (or an array) of transform coefficients.

[0033] In this document, at least one of quantization / dequantization and / or transform / inverse transform may be omitted. If the quantization / dequantization is omitted, the quantized transform coefficients may be referred to as transform coefficients. If the transform / inverse transform is omitted, the transform coefficients may be referred to as coefficients or residual coefficients, or may still be referred to as transform coefficients for uniformity of expression.

[0034] In this document, quantized transform coefficients and transform coefficients may be referred to as transform coefficients and scaled transform coefficients, respectively. In this case, residual information includes information about the transform coefficient(s), and the information about the transform coefficient(s) can be signaled via residual coding syntax. Transform coefficients are derived based on the residual information (or information about the transform coefficient(s)), and scaled transform coefficients are derived by inverse transform (scaling) of the transform coefficients. Residual samples are derived based on inverse transform (transform) of the scaled transform coefficients. This can be similarly applied / expressed in other parts of this document.

[0035] Technical features individually described in one drawing in this document may be implemented individually or simultaneously.

[0036] Hereinafter, preferred embodiments of the present invention will be described in more detail with reference to the accompanying drawings. Hereinafter, the same reference numerals will be used to refer to the same components in the drawings, and duplicated descriptions of the same components will be omitted.

[0037] FIG. 1 illustrates a schematic diagram of an example video / image coding system that can be applied to embodiments of this document.

[0038] As shown in Figure 1, a video / image coding system includes a first device (source device) and a second device (receiving device). The source device can transmit encoded video / image information or data to the receiving device in file or streaming form via a digital storage medium or a network.

[0039] The source device may include a video source, an encoding device, and a transmitting unit. The receiving device may include a receiving unit, a decoding device, and a renderer. The encoding device may be referred to as a video / video encoding device, and the decoding device may be referred to as a video / video decoding device. The transmitter may be included in the encoding device. The receiver may be included in the decoding device. The renderer may include a display unit, which may be a separate device or an external component.

[0040] A video source can acquire video / images through a video / image capture, synthesis, or generation process. A video source can include a video / image capture device and / or a video / image generation device. A video / image capture device can include, for example, one or more cameras, a video / image archive containing previously captured video / images, etc. A video / image generation device can include, for example, a computer, a tablet, a smartphone, etc., and can (electronically) generate video / images. For example, a virtual video / image can be generated via a computer, etc., in which case the video / image capture process can be replaced with a process in which related data is generated.

[0041] An encoding device can encode input video / images. The encoding device can perform a series of procedures such as prediction, transformation, and quantization for compression and coding efficiency. The encoded data (encoded video / image information) can be output in the form of a bitstream.

[0042] The transmitter can transmit the encoded video / image information or data output in the form of a bitstream to a receiver of a receiving device via a digital storage medium or a network in the form of a file or streaming. The digital storage medium can include various storage media such as USB, SD, CD, DVD, Blu-ray, HDD, SSD, etc. The transmitter can include elements for generating a media file in a predetermined file format and elements for transmission via a broadcasting / communication network. The receiver can receive / extract the bitstream and transmit it to a decoding device.

[0043] The decoding device can decode the video / image by performing a series of steps such as inverse quantization, inverse transform, and prediction, which correspond to the operations of the encoding device.

[0044] The renderer can render the decoded video / image, and the rendered video / image can be displayed via a display unit.

[0045] 2 is a diagram illustrating the configuration of a video / image encoding device to which the embodiments of this document can be applied. Hereinafter, the encoding device includes an image encoding device and / or a video encoding device.

[0046] As shown in FIG. 2, the encoding apparatus 200 may include an image partitioner 210, a predictor 220, a residual processor 230, an entropy encoder 240, an adder 250, a filter 260, and a memory 270. The predictor 220 may include an inter predictor 221 and an intra predictor 222. The residual processor 230 may include a transformer 232, a quantizer 233, a dequantizer 234, and an inverse transformer 235. The residual processor 230 may further include a subtractor 231. The adder 250 may be referred to as a reconstructor or a reconstructed block generator. The image dividing unit 210, the predicting unit 220, the residual processing unit 230, the entropy encoding unit 240, the adding unit 250, and the filtering unit 260 may be configured by one or more hardware components (e.g., an encoder chipset or a processor) depending on the embodiment. Also, the memory 270 may include a decoded picture buffer (DPB) or may be configured by a digital storage medium. The hardware components may further include the memory 270 as an internal / external component.

[0047] The image division unit 210 may divide an input image (or picture, frame) input to the encoding device 200 into one or more processing units. For example, the processing units may be called coding units (CUs). In this case, the coding units may be recursively divided from a coding tree unit (CTU) or a largest coding unit (LCU) using a quad-tree, binary-tree, ternary-tree (QTBTTT) structure. For example, one coding unit may be divided into multiple coding units of deeper depths based on a quad-tree structure, a binary tree structure, and / or a ternary structure. In this case, for example, the quad-tree structure may be applied first, and then the binary tree structure and / or the ternary structure may be applied. Alternatively, the binary tree structure may be applied first. The coding procedure according to the present disclosure may be performed based on a final coding unit that is not further divided. In this case, the largest coding unit may be used as the final coding unit based on coding efficiency according to image characteristics, or the coding unit may be recursively divided into coding units of lower depths as needed, and a coding unit of an optimal size may be used as the final coding unit. Here, the coding procedure may include procedures such as prediction, transformation, and restoration, which will be described later. As another example, the processing unit may further include a prediction unit (PU) or a transform unit (TU). In this case, the prediction unit and the transform unit may each be divided or partitioned from the final coding unit.The prediction unit may be a unit of sample prediction, and the transform unit may be a unit for deriving transform coefficients and / or a unit for deriving a residual signal from the transform coefficients.

[0048] The term "unit" may be used interchangeably with terms such as "block" or "area." In general, an MxN block can refer to a set of samples or transform coefficients consisting of M columns and N rows. A sample generally refers to a pixel or pixel value, and can refer to only a pixel / pixel value of a luma component or only a pixel / pixel value of a chroma component. A sample can also be used as a term corresponding to one pixel or pel of a picture (or image).

[0049] The encoding apparatus 200 subtracts a prediction signal (predicted block, prediction sample array) output from the inter prediction unit 221 or the intra prediction unit 222 from an input video signal (original block, original sample array) to generate a residual signal (residual block, residual sample array), and the generated residual signal is transmitted to the conversion unit 232. In this case, as shown in the figure, a unit in the encoder 200 that subtracts the prediction signal (predicted block, prediction sample array) from the input video signal (original block, original sample array) may be referred to as the subtraction unit 231. The prediction unit performs prediction on a current block (hereinafter, referred to as a current block) and generates a predicted block including prediction samples for the current block. The prediction unit may determine whether intra prediction or inter prediction is to be applied on a current block or CU basis. The prediction unit generates various information related to prediction, such as prediction mode information, and transmits the information to the entropy encoding unit 240, as will be described later in the description of each prediction mode. The prediction information is encoded in the entropy encoding unit 240 and output in the form of a bitstream.

[0050] The intra prediction unit 222 may predict the current block by referring to samples in the current picture. The referenced samples may be located neighboring or distant from the current block depending on the prediction mode. Prediction modes in intra prediction may include a plurality of non-directional modes and a plurality of directional modes. The non-directional modes may include, for example, DC mode and planar mode. The directional modes may include, for example, 33 directional prediction modes or 65 directional prediction modes depending on the granularity of the prediction direction. However, this is merely an example, and more or less directional prediction modes may be used depending on the settings. The intra prediction unit 222 may also determine the prediction mode to be applied to the current block using the prediction modes applied to neighboring blocks.

[0051] The inter prediction unit 221 may derive a predicted block for a current block based on a reference block (reference sample array) identified by a motion vector on a reference picture. To reduce the amount of motion information transmitted in inter prediction mode, the motion information may be predicted in units of blocks, sub-blocks, or samples based on the correlation of motion information between neighboring blocks and the current block. The motion information may include a motion vector and a reference picture index. The motion information may further include information on an inter prediction direction (such as L0 prediction, L1 prediction, or Bi prediction). In the case of inter prediction, the neighboring blocks may include spatial neighboring blocks in the current picture and temporal neighboring blocks in the reference picture. The reference picture including the reference block and the reference picture including the temporal neighboring block may be the same or different. The temporal neighboring block may be called a collocated reference block, a collocated CU (col CU), or the like, and the reference picture including the temporal neighboring block may be called a collocated picture (colPic). For example, the inter predictor 221 may construct a motion information candidate list based on neighboring blocks and generate information indicating which candidate is used to derive a motion vector and / or a reference picture index for the current block. Inter prediction may be performed based on various prediction modes, and for example, in the case of a skip mode or a merge mode, the inter predictor 221 may use motion information of neighboring blocks as motion information of the current block. In the case of the skip mode, unlike the merge mode, a residual signal may not be transmitted.In the case of motion vector prediction (MVP) mode, the motion vector of the neighboring block can be used as a motion vector predictor, and the motion vector of the current block can be indicated by signaling the motion vector difference.

[0052] The prediction unit 220 generates a prediction signal based on various prediction methods, which will be described later. For example, the prediction unit may apply intra prediction or inter prediction for predicting a block, or may simultaneously apply intra prediction and inter prediction. This may be referred to as combined inter and intra prediction (CIIP). The prediction unit may also use intra block copy (IBC) prediction mode or palette mode for predicting a block. The IBC prediction mode or palette mode is used for content image / video coding, such as games, such as screen content coding (SCC). IBC basically performs prediction within a current picture, but is similar to inter prediction in that it derives a reference block within the current picture. That is, IBC can use at least one of the inter prediction techniques described in this document. Palette mode may be considered an example of intra coding or intra prediction. When palette mode is applied, sample values ​​within a picture are signaled based on information about a palette table and a palette index.

[0053] The prediction signal generated by the prediction unit (including the inter prediction unit 221 and / or the intra prediction unit 222) is used to generate a reconstructed signal or a residual signal. The transform unit 232 generates transform coefficients by applying a transform technique to the residual signal. For example, the transform technique may include at least one of a discrete cosine transform (DCT), a discrete sine transform (DST), a Karhunen-Loeve transform (KLT), a graph-based transform (GBT), or a conditionally non-linear transform (CNT). Here, GBT refers to a transform obtained from a graph representing inter-pixel relationship information. CNT refers to a transform obtained based on a prediction signal generated using all previously reconstructed pixels. The transform process may be applied to pixel blocks having the same square size or non-square blocks of variable sizes.

[0054] The quantization unit 233 quantizes the transform coefficients and transmits them to the entropy encoding unit 240. The entropy encoding unit 240 encodes the quantized signal (information about the quantized transform coefficients) and outputs it as a bitstream. The information about the quantized transform coefficients may be referred to as residual information. The quantization unit 233 may rearrange the quantized transform coefficients in a block form into a one-dimensional vector form based on a coefficient scan order, and may generate information about the quantized transform coefficients based on the quantized transform coefficients in the one-dimensional vector form. The entropy encoding unit 240 may perform various encoding methods, such as exponential Golomb, context-adaptive variable length coding (CAVLC), and context-adaptive binary arithmetic coding (CABAC). In addition to the quantized transform coefficients, the entropy encoding unit 240 may also encode information required for video / image restoration (e.g., values ​​of syntax elements) together with or separately from the quantized transform coefficients. The encoded information (e.g., encoded video / picture information) may be transmitted or stored in the form of a bitstream in units of network abstraction layer (NAL) units. The video / picture information may further include information on various parameter sets, such as an adaptation parameter set (APS), a picture parameter set (PPS), a sequence parameter set (SPS), or a video parameter set (VPS). The video / picture information may also include general constraint information. In this document, information and / or syntax elements transmitted / signaled from an encoding device to a decoding device are included in the video / picture information. The video / picture information is encoded according to the encoding procedure described above and included in the bitstream.The bitstream can be transmitted via a network or stored in a digital storage medium. Here, the network can include a broadcasting network and / or a communication network, and the digital storage medium can include various storage media such as a USB, SD, CD, DVD, Blu-ray, HDD, SSD, etc. A transmitter (not shown) for transmitting and / or a storage unit (not shown) for storing the signal output from the entropy encoding unit 240 can be configured as an internal / external element of the encoding apparatus 200, or the transmitter can be included in the entropy encoding unit 240.

[0055] The quantized transform coefficients output from the quantization unit 233 may be used to generate a prediction signal. For example, a residual signal (residual block or residual sample) may be reconstructed by applying inverse quantization and inverse transform to the quantized transform coefficients via the inverse quantization unit 234 and the inverse transform unit 235. The adder 155 generates a reconstructed signal (reconstructed picture, reconstructed block, reconstructed sample array) by adding the reconstructed residual signal to the prediction signal output from the inter prediction unit 221 or the intra prediction unit 222. When there is no residual for the current block, such as when skip mode is applied, a predicted block may be used as the reconstructed block. The adder 250 may also be referred to as a reconstruction unit or a reconstructed block generator. The generated reconstructed signal may be used for intra prediction of the next block to be processed in the current picture, or may be used for inter prediction of the next picture after filtering, as described below.

[0056] Meanwhile, luma mapping with chrominance scaling (LMCS) can be applied during picture encoding and / or restoration.

[0057] The filtering unit 260 may apply filtering to the reconstructed signal to improve subjective / objective image quality. For example, the filtering unit 260 may apply various filtering methods to the reconstructed picture to generate a modified reconstructed picture and store the modified reconstructed picture in the memory 270, specifically, in the DPB of the memory 270. The various filtering methods may include, for example, deblocking filtering, sample adaptive offset (SAO), an adaptive loop filter, a bilateral filter, etc. The filtering unit 260 may generate various information related to filtering and transmit it to the entropy encoding unit 290, as will be described later in the description of each filtering method. The filtering information may be encoded by the entropy encoding unit 290 and output in the form of a bitstream.

[0058] The modified reconstructed picture transmitted to the memory 270 can be used as a reference picture in the inter prediction unit 280. When inter prediction is applied through this, the encoding apparatus can avoid prediction mismatch between the encoding apparatus 200 and the decoding apparatus, and can also improve coding efficiency.

[0059] The DPB of the memory 270 may store a modified reconstructed picture to be used as a reference picture in the inter predictor 221. The memory 270 may store motion information of a block from which motion information in the current picture is derived (or encoded) and / or motion information of a block in an already reconstructed picture. The stored motion information may be transmitted to the inter predictor 221 to be used as motion information of a spatially neighboring block or a temporally neighboring block. The memory 270 may store reconstructed samples of reconstructed blocks in the current picture and transmit them to the intra predictor 222.

[0060] 3 is a diagram illustrating the configuration of a video / image decoding device to which the embodiments of this document can be applied. Hereinafter, the decoding device includes an image decoding device and / or a video decoding device.

[0061] As shown in FIG. 3, the decoding device 300 may include an entropy decoder 310, a residual processor 320, a predictor 330, an adder 340, a filter 350, and a memory 360. The predictor 330 may include an inter predictor 332 and an intra predictor 331. The residual processor 320 may include a dequantizer 321 and an inverse transformer 321. Depending on the embodiment, the entropy decoding unit 310, the residual processor 320, the predictor 330, the adder 340, and the filter 350 may be implemented as a single hardware component (e.g., a decoder chipset or processor). The memory 360 may include a decoded picture buffer (DPB) or may be implemented as a digital storage medium. The hardware components may further include a memory 360 as an internal / external component.

[0062] When a bitstream including video / image information is input, the decoding apparatus 300 can reconstruct an image corresponding to the process in which the video / image information was processed by the encoding apparatus of FIG. 3. For example, the decoding apparatus 300 can derive units / blocks based on block division-related information obtained from the bitstream. The decoding apparatus 300 can perform decoding using a processing unit applied by the encoding apparatus. Accordingly, the processing unit for decoding can be, for example, a coding unit, and the coding unit can be divided from a coding tree unit or a maximal coding unit according to a quad tree structure, a binary tree structure, and / or a ternary tree structure. One or more transform units can be derived from the coding unit. The reconstructed image signal decoded and output by the decoding apparatus 300 can be reproduced via a reproduction device.

[0063] The decoding apparatus 300 receives a signal output from the encoding apparatus of FIG. 2 in the form of a bitstream, and the received signal is decoded via the entropy decoding unit 310. For example, the entropy decoding unit 310 may parse the bitstream to derive information (e.g., video / video information) necessary for image restoration (or picture restoration). The video / video information may further include information on various parameter sets, such as an adaptation parameter set (APS), a picture parameter set (PPS), a sequence parameter set (SPS), or a video parameter set (VPS). The video / video information may also include general constraint information. The decoding apparatus may further decode pictures based on the information on the parameter sets and / or the general constraint information. Signaled / received information and / or syntax elements, which will be described later in this document, may be decoded via the decoding procedure and obtained from the bitstream. For example, the entropy decoding unit 310 may decode information in a bitstream based on a coding method such as Exponential Golomb coding, CAVLC, or CABAC, and output values ​​of syntax elements required for image restoration and quantized values ​​of transform coefficients related to residuals. More specifically, the CABAC entropy decoding method receives bins corresponding to each syntax element in the bitstream, determines a context model using information on the syntax element to be decoded and decoding information on neighboring and current blocks or information on symbols / bins decoded in previous steps, predicts the occurrence probability of the bins based on the determined context model, and performs arithmetic decoding of the bins to generate symbols corresponding to the values ​​of each syntax element.In this case, after determining a context model, the CABAC entropy decoding method can update the context model using information on the decoded symbol / bin for the context model of the next symbol / bin. Prediction information from the information decoded by the entropy decoding unit 310 is provided to a prediction unit (inter prediction unit 332 and intra prediction unit 331), and residual values ​​entropy decoded by the entropy decoding unit 310, i.e., quantized transform coefficients and related parameter information, are input to the residual processing unit 320. The residual processing unit 320 can derive residual signals (residual blocks, residual samples, residual sample arrays). In addition, filtering information from the information decoded by the entropy decoding unit 310 is provided to the filtering unit 350. Meanwhile, a receiving unit (not shown) for receiving a signal output from the encoding apparatus may be further configured as an internal / external element of the decoding apparatus 300, or the receiving unit may be a component of the entropy decoding unit 310. Meanwhile, the decoding apparatus according to this document may be called a video / image / picture decoding apparatus, and the decoding apparatus may be divided into an information decoder (video / image / picture information decoder) and a sample decoder (video / image / picture sample decoder). The information decoder may include the entropy decoding unit 310, and the sample decoder may include at least one of the inverse quantization unit 321, the inverse transform unit 322, the addition unit 340, the filtering unit 350, the memory 360, the inter prediction unit 332, and the intra prediction unit 331.

[0064] The inverse quantization unit 321 may inverse quantize the quantized transform coefficients and output the transform coefficients. The inverse quantization unit 321 may rearrange the quantized transform coefficients in a two-dimensional block format. In this case, the rearrangement may be performed based on the coefficient scanning order performed in the encoding apparatus. The inverse quantization unit 321 may inverse quantize the quantized transform coefficients using a quantization parameter (e.g., quantization step size information) to obtain transform coefficients.

[0065] The inverse transform unit 322 performs inverse transform on the transform coefficients to obtain a residual signal (residual block, residual sample array).

[0066] The prediction unit may perform prediction on a current block and generate a predicted block including prediction samples for the current block. The prediction unit may determine whether intra prediction or inter prediction is applied to the current block based on information about the prediction output from the entropy decoding unit 310, and may determine a specific intra / inter prediction mode.

[0067] The predictor 320 may generate a prediction signal based on various prediction methods, which will be described later. For example, the predictor may apply intra prediction or inter prediction for predicting a block, or may simultaneously apply intra prediction and inter prediction. This may be referred to as combined inter and intra prediction (CIIP). The predictor may also use an intra block copy (IBC) prediction mode or a palette mode for predicting a block. The IBC prediction mode or palette mode may be used for content video / movie coding, such as games, such as screen content coding (SCC). IBC basically performs prediction within a current picture, but may be similar to inter prediction in that it derives a reference block within the current picture. That is, IBC may use at least one of the inter prediction techniques described in this document. The palette mode may be considered an example of intra coding or intra prediction. When the palette mode is applied, information regarding a palette table and a palette index is included in the video / picture information and signaled.

[0068] The intra prediction unit 331 may predict a current block by referring to samples in a current picture. The referenced samples may be located adjacent to or distant from the current block depending on the prediction mode. In intra prediction, prediction modes may include a plurality of non-directional modes and a plurality of directional modes. The intra prediction unit 331 may also determine a prediction mode to be applied to the current block by using prediction modes applied to neighboring blocks.

[0069] The inter prediction unit 332 may derive a predicted block for the current block based on a reference block (reference sample array) identified by a motion vector on a reference picture. To reduce the amount of motion information transmitted in inter prediction mode, the motion information may be predicted in units of blocks, sub-blocks, or samples based on the correlation of motion information between neighboring blocks and the current block. The motion information may include a motion vector and a reference picture index. The motion information may further include information on the inter prediction direction (e.g., L0 prediction, L1 prediction, Bi prediction, etc.). In the case of inter prediction, the neighboring blocks may include spatial neighboring blocks in the current picture and temporal neighboring blocks in the reference picture. For example, the inter prediction unit 332 may construct a motion information candidate list based on the neighboring blocks and derive a motion vector and / or a reference picture index for the current block based on received candidate selection information. Inter prediction may be performed based on various prediction modes, and the prediction information may include information indicating the inter prediction mode for the current block.

[0070] The adder 340 may generate a reconstructed signal (reconstructed picture, reconstructed block, reconstructed sample array) by adding the acquired residual signal to the predicted signal (predicted block, predicted sample array) output from the predictor 330. When there is no residual for the current block, such as when a skip mode is applied, the predicted block may be used as the reconstructed block.

[0071] The adder 340 may be referred to as a reconstruction unit or a reconstruction block generator. The generated reconstruction signal may be used for intra prediction of a next block to be processed in the current picture, may be output after filtering as described below, or may be used for inter prediction of a next picture.

[0072] Meanwhile, LMCS (luma mapping with chroma scaling) can be applied during picture decoding.

[0073] The filtering unit 350 may apply filtering to the reconstructed signal to improve subjective / objective image quality. For example, the filtering unit 350 may apply various filtering methods to the reconstructed picture to generate a modified reconstructed picture, and may transmit the modified reconstructed picture to the memory 60, specifically, to the DPB of the memory 360. The various filtering methods may include, for example, deblocking filtering, sample adaptive offset, an adaptive loop filter, a bilateral filter, etc.

[0074] The (modified) reconstructed picture stored in the DPB of the memory 360 can be used as a reference picture in the inter predictor 332. The memory 360 can store motion information of a block from which motion information in the current picture is derived (or decoded) and / or motion information of a block in an already reconstructed picture. The stored motion information can be transmitted to the inter predictor 332 to be used as motion information of a spatially neighboring block or a temporally neighboring block. The memory 360 can store reconstructed samples of reconstructed blocks in the current picture and transmit them to the intra predictor 331.

[0075] In this document, the embodiments described for the filtering unit 260, inter prediction unit 221 and intra prediction unit 222 of the encoding device 200 are also applied identically or correspondingly to the filtering unit 350, inter prediction unit 332 and intra prediction unit 331 of the decoding device 300, respectively.

[0076] As described above, prediction is performed to improve compression efficiency during video coding. Accordingly, a predicted block including predicted samples for a current block, which is a block to be coded, can be generated. Here, the predicted block includes predicted samples in the spatial domain (or pixel domain). The predicted block is derived in the same way by an encoding device and a decoding device. The encoding device can improve image coding efficiency by signaling to a decoding device information (residual information) regarding the residual between the original block and the predicted block, rather than the original sample values ​​of the original block themselves. The decoding device can derive a residual block including residual samples based on the residual information, add the residual block and the predicted block to generate a reconstructed block including reconstructed samples, and generate a reconstructed picture including the reconstructed block.

[0077] The residual information may be generated through a transform and quantization procedure. For example, an encoding apparatus may derive a residual block between the original block and the predicted block, perform a transform procedure on residual samples (residual sample array) included in the residual block to derive transform coefficients, and perform a quantization procedure on the transform coefficients to derive quantized transform coefficients, and then signal the related residual information (via a bitstream) to a decoding apparatus. Here, the residual information may include information such as value information, position information, transform technique, transform kernel, and quantization parameter of the quantized transform coefficients. The decoding apparatus may derive residual samples (or residual blocks) by performing an inverse quantization / inverse transform procedure based on the residual information. The decoding apparatus may generate a reconstructed picture based on the predicted block and the residual block. The encoding apparatus may also derive a residual block by inverse quantizing / inverse transforming the quantized transform coefficients for reference for inter-prediction of a future picture, and generate a reconstructed picture based on the residual block.

[0078] The following drawings are created to illustrate a specific example of the present document. The names of specific devices or specific terms or names (e.g., syntax names, etc.) shown in the drawings are for illustrative purposes only, and the technical features of the present document are not limited to the specific names used in the following drawings.

[0079] FIG. 4 shows an example of a general video / image encoding method to which the embodiments of this document can be applied.

[0080] The method disclosed in Fig. 4 may be performed by the encoding apparatus 200 of Fig. 2. Specifically, S400 is performed by the inter prediction unit 221 or the intra prediction unit 222 of the encoding apparatus 200, and S410, S420, S430, and S440 are performed by the subtraction unit 231, the transformation unit 232, the quantization unit 233, and the entropy encoding unit 240 of the encoding apparatus 200, respectively.

[0081] As shown in Fig. 4, an encoding apparatus derives prediction samples by predicting a current block (S400). The encoding apparatus determines whether to perform inter prediction or intra prediction on the current block, and determines a specific inter prediction mode or a specific intra prediction mode based on the RD cost. The encoding apparatus derives prediction samples for the current block according to the determined mode.

[0082] The encoding apparatus derives residual samples by comparing the original samples and predicted samples for the current block (S410).

[0083] The encoding apparatus derives transform coefficients through a transform procedure on the residual samples (S420), and quantizes the derived transform coefficients to derive quantized transform coefficients (S430).

[0084] Quantization is performed based on a quantization parameter. The transform step and / or the quantization step may be omitted. When the transform step is omitted, the (quantized) (residual) coefficients for the residual samples are coded according to the residual coding technique described below. For the sake of terminology consistency, the (quantized) (residual) coefficients may also be called (quantized) transform coefficients.

[0085] The encoding device encodes video information including prediction information and residual information and outputs the encoded video information in the form of a bitstream (S440). The prediction information is information related to a prediction procedure, including prediction mode information and motion information (e.g., when inter-prediction is applied). The residual information includes information related to quantized transform coefficients. The residual information may be entropy coded. Alternatively, the residual information may include information related to (quantized) (residual) coefficients.

[0086] The output bitstream is transmitted to a decoding device via a storage medium or a network.

[0087] FIG. 5 shows an example of a general video / image decoding method to which the embodiments of this document can be applied.

[0088] The method disclosed in Figure 5 may be performed by the decoding apparatus 300 of Figure 3. Specifically, step S500 is performed by the inter predictor 332 or the intra predictor 331 of the decoding apparatus 300. In step S500, the procedure of decoding prediction information included in the bitstream and deriving values ​​of related syntax elements is performed by the entropy decoding unit 310 of the decoding apparatus 300. Steps S510, S520, S530, and S540 are performed by the entropy decoding unit 310, the inverse quantizer 321, the inverse transformer 322, and the adder 340 of the decoding apparatus 300, respectively.

[0089] As shown in Figure 5, the decoding apparatus performs operations corresponding to those performed by the encoding apparatus. The decoding apparatus performs inter-prediction or intra-prediction on a current block based on received prediction information to derive prediction samples (S500).

[0090] The decoding apparatus derives quantized transform coefficients for the current block based on the received residual information (S510). The decoding apparatus derives the quantized transform coefficients from the residual information by entropy decoding.

[0091] The decoding apparatus dequantizes the quantized transform coefficients to derive transform coefficients (S520). The dequantization is performed based on the quantization parameter.

[0092] The decoding apparatus derives residual samples by performing an inverse transform procedure on the transform coefficients (S530).

[0093] The inverse transform and / or inverse quantization steps may be omitted. If the inverse transform steps are omitted, the (quantized) (residual) coefficients can be derived from the residual information, and the residual samples can be derived based on the (quantized) coefficients.

[0094] The decoding apparatus generates reconstructed samples for the current block based on the predicted samples and the residual samples, and generates a reconstructed picture based on the reconstructed samples (S540). Thereafter, the in-loop filtering procedure can be further applied to the reconstructed picture, as described above.

[0095] As described above, the encoding device performs entropy encoding based on various encoding methods, such as exponential Golomb coding, CAVLC (context-adaptive variable length coding), CABAC (context-adaptive binary arithmetic coding), etc. The decoding device performs entropy decoding based on a coding method, such as exponential Golomb coding, CAVLC, or CABAC. The entropy encoding / decoding procedure will now be described.

[0096] Figure 6 illustrates an example of an entropy encoding method to which the embodiments of the present document can be applied, and Figure 7 illustrates an entropy encoding unit in an encoding device. The entropy encoding unit in the encoding device of Figure 7 can be applied to the entropy encoding unit 240 of the encoding device 200 of Figure 2 in an identical or corresponding manner.

[0097] As shown in Figures 6 and 7, an encoding apparatus (entropy encoding unit) performs an entropy coding procedure on image / video information. The image / video information includes partitioning-related information, prediction-related information (e.g., inter / intra prediction classification information, intra prediction mode information, inter prediction mode information, etc.), residual information, in-loop filtering-related information, etc., or various syntax elements related thereto. Entropy coding is performed on a syntax element basis. S600 to S610 may be performed by the entropy encoding unit 240 of the encoding apparatus 200 of Figure 2 described above.

[0098] The encoding device binarizes the target syntax element (S600). Here, the binarization is performed based on various binarization methods such as a truncated rice binarization process or a fixed-length binarization process, and the binarization method for the target syntax element can be predefined. The binarization procedure is performed by a binarization unit 242 in an entropy encoding unit 240.

[0099] The encoding device performs entropy encoding on the target syntax element (S610). The encoding device can perform normal coding-based (context-based) or bypass coding-based encoding on the bin string of the target syntax element based on an entropy coding technique such as CABAC (context-adaptive arithmetic coding) or CAVLC (context-adaptive variable length coding), and the output is included in the bitstream. The entropy encoding procedure is performed by the entropy encoding processing unit 243 in the entropy encoding unit 240. As mentioned above, the bitstream can be transmitted to the decoding device via a (digital) storage medium or a network.

[0100] Figure 8 shows an example of an entropy decoding method to which the embodiments of the present document can be applied, and Figure 9 shows an entropy decoding unit in a decoding device. The entropy decoding unit in the decoding device of Figure 9 can be applied in the same or corresponding manner to the entropy decoding unit 310 of the decoding device 300 of Figure 3 described above.

[0101] As shown in Figures 8 and 9, a decoding apparatus (entropy decoding unit) decodes encoded image / video information. The image / video information includes partitioning-related information, prediction-related information (e.g., inter / intra prediction classification information, intra prediction mode information, inter prediction mode information, etc.), residual information, in-loop filtering-related information, etc., or various syntax elements related thereto. Entropy coding is performed in units of syntax elements. Steps S800 to S810 may be performed by the entropy decoding unit 310 of the decoding apparatus 300 of Figure 3 described above.

[0102] The decoding device performs binarization on the target syntax element (S800). Here, the binarization is performed based on various binarization methods, such as a truncated rice binarization process or a fixed-length binarization process, and the binarization method for the target syntax element can be predefined. The decoding device derives available bin strings (bin string candidates) for the available values ​​of the target syntax element through the binarization procedure. The binarization procedure can be performed by the binarization unit 312 in the entropy decoding unit 310.

[0103] The decoding device performs entropy decoding on the target syntax element (S810). The decoding device sequentially decodes and parses each bin for the target syntax element from the input bit(s) in the bitstream, and compares the derived bin string with the available bin string for the syntax element. If the derived bin string is identical to one of the available bin strings, the value corresponding to that bin string can be derived as the value of the syntax element. If not, the next bit in the bitstream is further parsed, and the above procedure is repeated. This process allows specific information (specific syntax element) to be signaled using variable-length bits without using start or end bits for the specific information in the bitstream. This allows relatively fewer bits to be allocated to low values, improving overall coding efficiency.

[0104] The decoding device can perform context-based or bypass-based decoding on each bin in the bin string from the bitstream based on an entropy coding technique such as CABAC or CAVLC. Here, the bitstream includes various information for image / video decoding as described above. As described above, the bitstream can be transmitted to the decoding device via a (digital) storage medium or a network.

[0105] In this document, a table containing syntax elements (syntax table) is used to indicate the signaling of information from an encoding device to a decoding device. The order of syntax elements in the syntax table used in this document indicates the parsing order of the syntax elements from the bitstream. The encoding device can configure and encode the syntax table so that the syntax elements are parsed in the parsing order in the decoding device, and the decoding device can parse and decode the syntax elements of the syntax table from the bitstream according to the parsing order to obtain the values ​​of the syntax elements.

[0106] Meanwhile, as described above, residual samples are derived as quantized transform coefficients through a transform and quantization process. The quantized transform coefficients may also be referred to as transform coefficients. In this case, the transform coefficients within a block may be signaled in the form of residual information. The residual information includes a residual coding syntax. That is, an encoding device constructs a residual coding syntax using the residual information, encodes it, and outputs it in the form of a bitstream, and a decoding device decodes the residual coding syntax from the bitstream to derive residual (quantized) transform coefficients. The residual coding syntax includes syntax elements indicating whether a transform has been applied to the block, the position of the last significant transform coefficient within the block, whether significant transform coefficients exist within a sub-block, and the size / sign of the significant transform coefficients, as described below.

[0107] For example, (quantized) transform coefficients can be encoded and / or decoded based on syntax elements such as last_sig_coeff_x_prefix, last_sig_coeff_y_prefix, last_sig_coeff_x_suffix, last_sig_coeff_y_suffix, coded_sub_block_flag, sig_coeff_flag, par_level_flag, abs_level_gtX_flag, abs_remainder, coeff_sign_flag, and dec_abs_level included in the residual information. This is also called residual (data) coding or (transform) coefficient coding. In this case, the transform / quantization process may be omitted. In this case, the values ​​of the residual samples can be coded and signaled according to a predetermined method. Syntax elements related to residual data encoding / decoding are shown in Table 1 below.

[0108] Table 1-1

[0109] Table 1-2

[0110] Table 1-3

[0111] Table 1-4

[0112] Referring to Table 1, last_sig_coeff_x_prefix, last_sig_coeff_y_prefix, last_sig_coeff_x_suffix, and last_sig_coeff_y_suffix are syntax elements that encode (x, y) position information of the last non-zero coefficient in an associated block. The associated block may be a coding block (CB) or a transform block (TB). CB and TB may be mixed in the transform (and quantization) and residual coding procedures. For example, as described above, residual samples are derived for the CB, and (quantized) transform coefficients can be derived by transforming and quantizing the residual samples. Information (or syntax elements) that efficiently indicate (the position, size, sign, etc.) of the (quantized) transform coefficients may be generated and signaled by the residual coding procedure. Quantized transform coefficients may be simply referred to as transform coefficients. Generally, if CB is not larger than the maximum TB, the size of CB may be the same as the size of TB, in which case the target block to be transformed (and quantized) and residually coded may be referred to as CB or TB. Alternatively, if CB is larger than the maximum TB, the target block to be transformed (and quantized) and residually coded may be referred to as TB. Hereinafter, it will be described that syntax elements related to residual coding are signaled in units of transform block (TB), but this is merely an example, and as mentioned above, TB can be used interchangeably with coding block (CB).

[0113] Meanwhile, different residual coding schemes are applied depending on whether a transform skip is applied for residual coding. As an example, whether a transform skip is applied is indicated using a transform skip flag syntax element, and residual coding can be branched according to the value of the transform skip flag syntax element, transform_skip_flag. That is, different syntax elements are used for residual coding depending on the value of the transform skip flag (depending on whether a transform skip is applied). Residual coding used when a transform skip is not applied (i.e., when a transform is applied) is called Regular Residual Coding (RRC), and residual coding when a transform skip is not applied (i.e., when a transform is not applied) is called Transform Skip Residual Coding (TSRC).

[0114] Table 2 below shows how residual coding is branched based on the syntax element of the transform skip flag.

[0115] [Table 2]

[0116] Referring to Table 2 above, if transform skip is not applied (e.g., the value of transform_skip_flag is 0), regular residual coding is performed based on the syntax elements disclosed in Table 1 above. Alternatively, if transform skip is applied (e.g., the value of transform_skip_flag is 1), transform skip residual coding is performed based on the syntax elements disclosed in Table 3 below.

[0117] Table 3 below shows the syntax elements for transform skip residual coding.

[0118] [Table 3-1]

[0119] [Table 3-2]

[0120] For example, a transform skip flag indicating whether or not a transform block is to be skipped is parsed to determine whether the transform skip flag is 1. If the value of the transform skip flag is 1, the syntax elements sig_coeff_flag, coeff_sign_flag, abs_level_gtx_flag, par_level_flag, and / or abs_remainder related to the residual coefficients of the transform block are parsed as shown in Table 3, and the residual coefficients are derived based on the syntax elements. In this case, the syntax elements may be parsed sequentially, or the parsing order may be changed. Here, abs_level_gtx_flag may indicate abs_level_gt1_flag, abs_level_gt3_flag, abs_level_gt5_flag, abs_level_gt7_flag, and / or abs_level_gt9_flag. For example, abs_level_gtx_flag[n][j] may be a flag indicating whether the absolute value of the transform coefficient level (or the value obtained by shifting the transform coefficient level by 1 to the right) at scanning position n is greater than (j<<1)+1. The (j<<1)+1 may be replaced with a predetermined critical value such as a first critical value or a second critical value, depending on the case.

[0121] Also, when the value of the transform skip flag is 0, the syntax elements sig_coeff_flag, abs_level_gtx_flag, par_level_flag, abs_remainder, dec_abs_level, and coeff_sign_flag related to the residual coefficients of the transform block are parsed, and the residual coefficients are derived based on the syntax elements, as shown in Table 1. In this case, the syntax elements may be parsed sequentially, or the parsing order may be changed. Here, abs_level_gtx_flag may indicate abs_level_gt1_flag and / or abs_level_gt3_flag.

[0122] As described above, an encoding apparatus derives residual blocks (residual samples) based on blocks (prediction samples) predicted by intra / inter / IBC / palette prediction, etc., and applies transform and quantization to the derived residual samples to derive quantized transform coefficients. Information about the quantized transform coefficients (residual information) is included in a residual coding syntax and is output in the form of a bitstream after encoding. A decoding apparatus obtains information about the quantized transform coefficients (residual information) from the bitstream and decodes the information to derive quantized transform coefficients. The decoding apparatus derives residual samples through inverse quantization / inverse transform based on the quantized transform coefficients. As described above, at least one of the quantization / inverse quantization and / or transform / inverse transform may be omitted. If the transform / inverse transform is omitted, the transform coefficients may be called coefficients or residual coefficients, or may still be called transform coefficients for consistency of expression. Whether the transform / inverse transform is omitted is signaled based on the transform_skip_flag. For example, if the value of transform_skip_flag is 1, it indicates that the transform / inverse transform is omitted, and this is called a transform skip mode.

[0123] Generally, in video / image coding, the quantization rate can be changed, and the compression rate can be adjusted using the changed quantization rate. From the viewpoint of implementation, a quantization parameter (QP) can be used instead of directly using the quantization rate, considering the complexity. For example, a quantization parameter having an integer value ranging from 0 to 63 can be used, and each quantization parameter value corresponds to an actual quantization rate. Also, for example, the quantization parameter (QP) for a luma component (luma sample) can be Y ) and the quantization parameter (QP C ) can be set differently.

[0124] The quantization process takes the transform coefficients (C) as input and calculates the quantization rate (Q step ), and a quantized transform coefficient C' is obtained based on this. In this case, taking into consideration the computational complexity, the quantization rate is multiplied by a scale to convert it into an integer, and a shift operation is performed by the value corresponding to the scale value. The quantization scale can be derived based on the product of the quantization rate and the scale value. That is, the quantization scale is derived based on the QP. For example, the quantization scale can be applied to the transform coefficient C, and the quantized transform coefficient C' can be derived based on this.

[0125] The inverse quantization process is the reverse of the quantization process, and applies the quantization rate (Q step ) and reconstructed transform coefficients (C'') are obtained based on the quantization parameter. In this case, a level scale is derived based on the quantization parameter, and the level scale is applied to the quantized transform coefficients (C') to derive reconstructed transform coefficients (C''). The reconstructed transform coefficients (C'') may differ slightly from the original transform coefficients (C) due to losses in the transform and / or quantization process. Therefore, the encoding device also performs inverse quantization, just like the decoding device.

[0126] Prediction may also be based on palette coding. Palette coding is a useful technique for representing blocks containing a small number of unique color values. Instead of applying prediction and transformation to the block, palette mode signals an index to indicate the value of each sample. Palette mode is useful for saving video memory buffer space. Blocks can be coded using palette mode (e.g., MODE_PLT). To decode a block encoded in this way, the decoder must decode the palette entries and indices. Palette entries are indicated by a palette table and encoded by a palette table coding tool.

[0127] Palette coding is also called (intra) palette mode or (intra) palette coding mode. The current block can be reconstructed using palette coding or palette mode. Palette coding is an example of intra coding or an intra prediction method. However, similar to the skip mode described above, a separate residual value for the block may not be signaled.

[0128] For example, when the palette mode is selected, information about the palette table may be signaled. The palette table includes an index corresponding to each pixel. The palette table may be used to construct a palette prediction table from pixel values ​​used in a previous block. For example, previously used pixel values ​​are stored in a specific buffer (palette predictor), and palette predictor information (palette_predictor_run) for constructing the current palette is received from this buffer. That is, the palette predictor includes data indicating an index for at least a portion of the palette index map of the current block. If the palette prediction entries constructed from the palette predictor are not sufficient to represent the current block, pixel information about the current palette entries is transmitted separately.

[0129] Palette mode is signaled at the CU level and can generally be used when most of the pixels in a CU can be represented as a set of representative pixel values. That is, palette mode allows samples in a CU to be expressed as a set of representative pixel values. Such a set may be called a palette. For samples with values ​​close to pixel values ​​in the palette, a palette index (palette_idx_idc) or information pointing to an index (run_copy_flag, copy_above_indices_flag) corresponding to the pixel value in the palette may be signaled. For samples with pixel values ​​other than palette entries, the sample may be represented as an escape symbol, and the quantized sample value may be directly signaled. In this document, pixels or pixel values ​​may be referred to as samples or sample values.

[0130] To decode a block coded in palette mode, the decoder needs palette entry information and palette index information. If the palette index corresponds to an escape symbol, the (quantized) escape value is signaled in an additional component. In addition, the encoder must derive the appropriate palette for the CU and transmit it to the decoder.

[0131] For efficient coding of palette entries, a palette predictor is maintained. The palette predictor and the maximum palette size can be signaled in the SPS. Alternatively, the palette predictor and the maximum palette size can be predefined. For example, the palette predictor and the maximum palette size are defined as 31 and 15, respectively, depending on whether the current block is single-tree or dual-tree. In the VVC standard, the sps_palette_enabled_flag can be transmitted to indicate whether palette mode is enabled. Then, the pred_mode_plt_coding flag is transmitted to indicate whether the current coding unit is coded in palette mode. The palette predictor is initialized at the beginning of each brick or slice.

[0132] For each entry in the palette predictor, a reuse flag can be signaled to indicate whether it is currently part of the palette. The reuse flag can be transmitted using a run-length coding of 0. The number of new palette entries is then increased by 0. thThe new palette entry can be signaled using exponential Golomb coding of the current order. Finally, the component values ​​for the new palette entry can be signaled. After encoding the current CU, the palette predictor is updated with the current palette, and entries of the previous palette predictor that are not reused in the current palette can be added to the end of the new palette predictor (palette stuffing) until the maximum allowed size is reached.

[0133] To code the palette index map, the index can be coded using horizontal and vertical traverse scans. The scan order can be explicitly signaled from the bitstream using flag information (e.g., palette_transpose_flag).

[0134] Meanwhile, palette indices are coded using two palette sample modes, for example, 'INDEX' mode and 'COPY_ABOVE' mode. The palette mode can be signaled using a flag indicating whether it is 'INDEX' mode or 'COPY_ABOVE' mode. In this case, the escape symbol is signaled in 'INDEX' mode and assigned the same index as the current palette size. For example, if the current palette size is 10, indexes 0 to 9 represent entry indexes within the palette, and index 10 represents the index for the escape symbol. When horizontal scanning is used, the flag can be signaled excluding the top row. When vertical scanning is used or the previous mode is 'COPY_ABOVE' mode, the flag can be signaled excluding the first column. In 'COPY_ABOVE' mode, the palette index of the sample in the row above is copied. In 'INDEX' mode, the palette index is explicitly signaled. For both "INDEX" and "COPY_ABOVE" modes, a run value is signaled indicating the number of next samples to be coded using the same mode. If an escape symbol is part of a run in "INDEX" or "COPY_ABOVE" mode, an escape component value can be signaled for each escape symbol.

[0135] Coding for palette indices is as follows: First, the number of indices for a CU is signaled. Then, the actual indices for the entire CU are signaled using fixed length coding. The index number and index are coded in bypass mode, which allows index-related bypass bins to be grouped together. Next, the palette sample mode (copy_above_palette_indices_flag) and runs are signaled in an interleaved manner. Finally, the component escape values ​​corresponding to the escape samples for the entire CU are grouped together and coded in bypass mode.

[0136] Table 4 below shows an example of a syntax structure including syntax elements related to palette mode based coding for a coding unit, and Table 5 below shows the semantics for the syntax elements of Table 4.

[0137] [Table 4-1]

[0138] [Table 4-2]

[0139] [Table 4-3]

[0140] [Table 5-1]

[0141] [Table 5-2]

[0142] [Table 5-3]

[0143] [Table 5-4]

[0144] [Table 5-5]

[0145] Referring to Tables 4 and 5, when the palette mode is applied to the current block (i.e., the current coding unit), the palette coding syntax (e.g., palette_coding()) shown in Table 4 is parsed / signaled.

[0146] For example, a palette table can be configured based on palette entry information, which includes syntax elements such as palette_predictor_run, num_signalled_palette_entries, and new_palette_entries.

[0147] Also, a palette index map for the current block can be constructed based on the palette index information. The palette index information includes syntax elements such as num_palette_indices_minus1, palette_idx_idc, palette_transpose_flag, etc. Based on the palette index information, a palette index (e.g., PaletteIndexIdc) can be derived for samples in the current block while traversing along the traverse scan direction (vertical or horizontal) to construct a palette index map (e.g., PaletteIndexMap).

[0148] Also, sample values ​​for palette entries in a palette table can be derived based on the palette index map, and reconstructed samples of the current block can be generated based on the sample values ​​mapped to the palette entries.

[0149] Also, if there is a sample with an escape value in the current block (i.e., the value of palette_escape_val_present_flag is 1), an escape value for the current block is derived based on the escape information. The escape information includes syntax elements such as palette_escape_val_present_flag and palette_escape_val. For example, an escape value for an escape-coded sample in the current block is derived based on quantized escape value information (e.g., palette_escape_val). A reconstructed sample of the current block can be generated based on the escape value.

[0150] Meanwhile, in the encoding / decoding process, a block differential pulse coded modulation (BDPCM) technique is used. BDPCM may also be called quantized residual block-based delta pulse code modulation (RDPCM).

[0151] When predicting a block using BDPCM, reconstructed samples can be used to predict rows or columns of the block line-by-line. In this case, the reference samples used can be unfiltered samples. The BDPCM direction indicates whether vertical or horizontal prediction is used. That is, when BDPCM is applied, the vertical or horizontal direction is selected as the BDPCM direction, and prediction can be performed in the BDPCM direction. A prediction error is quantized in the spatial domain, and samples are reconstructed by adding the dequantized prediction error to the prediction (i.e., the prediction sample). The prediction error refers to a residual. As an alternative to BDPCM, quantized residual-domain BDPCM can be proposed, and the prediction direction and signaling can be the same as those of BDPCM applied to the spatial domain. That is, through quantized residual-domain BDPCM, the quantized coefficients themselves can be stacked like DPCM (Delta Pulse Code Modulation), and then the residual can be reconstructed by dequantization. Therefore, the term "quantized residual domain BDPCM" can be used to mean applying DPCM in the residual coding stage. Hereinafter, the term "quantized residual domain" refers to a domain of quantized residual samples, in which residuals derived based on prediction are quantized without transform. For example, the quantized residual domain includes quantized residuals (or quantized residual coefficients) to which a transform skip is applied, i.e., the transform is skipped but quantization is applied to the residual samples. Alternatively, for example, the quantized residual domain includes quantized transform coefficients.

[0152] As described above, BDPCM can be applied to the quantized residual domain, which includes quantized residuals (or quantized residual coefficients), with transform skip applied to the residuals. That is, when BDPCM is applied, transform is skipped and quantization is applied to residual samples. Alternatively, the quantized residual domain can include quantized transform coefficients. A flag indicating whether BDPCM is applicable is signaled at the sequence level (SPS), and such a flag can be signaled only if transform skip mode is signaled as possible in the SPS. This flag may be called a BDPCM available flag or an SPS BDPCM available flag.

[0153] When BDPCM is applied, intra prediction is performed on the entire block by sample copying in a prediction direction similar to the intra prediction direction (e.g., vertical prediction or horizontal prediction). The residual, which is the difference between the original and predicted block, is quantized without being transformed, and the delta value between the quantized residual and the predictor for the horizontal or vertical direction (i.e., the quantized residual for the horizontal or vertical direction), i.e., the difference value, is coded.

[0154] If BDPCM is applicable, and the CU size is smaller than or equal to MaxTsSize (maximum transform skip block size) for luma samples and the CU is coded using intra prediction, flag information may be transmitted at the CU level. The flag information may be referred to as a BDPCM flag. Here, MaxTsSize may refer to the maximum block size for which transform skip mode is allowed. The flag information may indicate whether normal intra coding or BDPCM is applied. If BDPCM is applied, a BDPCM prediction direction flag indicating whether the prediction direction is horizontal or vertical may be transmitted. The BDPCM prediction direction flag is also referred to as a BDPCM direction flag. Thereafter, the block may be predicted through a normal horizontal or vertical intra prediction process using unfiltered reference samples. Furthermore, residuals are quantized, and a difference value between each quantized residual and its predictor, e.g., an already quantized residual at a neighboring position in the horizontal or vertical direction, according to the BDPCM prediction direction, may be coded.

[0155] Meanwhile, as described above, the information (syntax elements) in the syntax table disclosed in this document is included in image / video information, constructed / encoded in an encoding device, and transmitted to a decoding device in the form of a bitstream. The decoding device parses / decodes the information (syntax elements) in the syntax table. The decoding device can perform a decoding procedure (prediction, (transform skip-based) residual processing, BDPCM, palette coding, etc.) for the current block based on the decoded information.

[0156] Hereinafter, this document proposes an efficient method for parsing / signaling dependent syntax elements for transform skip-related high-level syntax elements and / or palette coding-related high-level syntax elements. That is, according to the embodiment of this document, it is possible to distinguish whether coding is possible or not depending on the dependency or non-dependency of information that is essential or used auxiliary in performing transform skip and / or palette coding during video / image coding, thereby enabling efficient coding.

[0157] In video coding, coding tool switches can be defined within a specific high-level syntax (HLS). In the case of conventional VVC, flag information for each coding tool can be defined in the SPS. Furthermore, VVC standardization has been promoted with the aim of maintaining independence between high-level syntax sets (e.g., video parameter set (VPS), sequence parameter set (SPS), picture parameter set (PPS), adaptation parameter set (APS), decoding parameter set (DPS), slice header, etc.). Therefore, within the high-level syntax set where coding tool flags exist, there are many syntax elements with dependencies. In one or more embodiments of this document, we propose a method for parsing / signaling dependent high-level syntax elements using transform skipping and / or palette coding.

[0158] As an example, this document proposes a method for saving transmitted bits by determining whether to parse / signal a syntax element that is dependent on a high-level syntax element related to conversion skip according to the dependent condition. As an example, this document proposes a method for parsing a high-level syntax element that has a dependency according to whether conversion skip is available or not according to a conversion skip (available) flag.

[0159] For example, syntax elements dependent on transform skip-based coding include a transform skip (enabled) flag (e.g., sps_transform_skip_enabled_flag), minimum quantization parameter information for transform skip (e.g., min_qp_prime_ts_minus4), information on whether BDPCM is applicable (e.g., sps_bdpcm_enabled_flag), etc. For example, if the value of the transform skip (enabled) flag is defined as 1, the related flag or information syntax element must be transmitted, but if the value of the transform skip (enabled) flag is defined as 0, the syntax elements except for the transform skip (enabled) flag syntax element may not be transmitted.

[0160] That is, when transform skip is performed according to the value of a transform skip (available) flag in a high-level syntax HLS (e.g., VPS, SPS, PPS, APS, DPS, Slice header, etc.), a method is proposed for transmitting high-level syntax elements dependent on whether transform skip is performed, such as minimum quantization parameter information for a transform skip block, whether BDPCM is applied, etc. Also, the proposed method is not limited to only the syntax elements mentioned in this embodiment, but may include all high-level syntax elements defined in a high-level syntax set including a transform skip (available) flag, which have dependency depending on whether transform skip is performed.

[0161] As mentioned above, syntax elements related to transform skip-based coding can be defined in a high-level syntax set and can be defined within a sequence parameter set (SPS) as in the example of Table 6 below.

[0162] [Table 6]

[0163] Furthermore, for example, the semantics of the syntax elements of the SPS syntax related to the above-mentioned embodiment can be shown as in Table 7 below.

[0164] [Table 7]

[0165] Referring to Tables 6 and 7, syntax elements related to transform skipping can be defined in SPS, including sps_transform_skip_enabled_flag, sps_bdpcm_enabled_flag, and min_qp_prime_ts_minus4 syntax elements.

[0166] The sps_transform_skip_enabled_flag syntax element indicates whether transform skipping is enabled based on whether its value is 0 or 1. For example, if the value of sps_transform_skip_enabled_flag is 1, it indicates that transform skipping is enabled, and in this case, transform_skip_flag can be parsed / signaled via the transform unit syntax. Here, the transform_skip_flag syntax element indicates whether a transform can be applied to the associated transform block. If the value of sps_transform_skip_enabled_flag is 0, it indicates that transform skipping is not enabled, and in this case, transform_skip_flag is not parsed / signaled in the transform unit syntax. In other words, it is possible to indicate whether transform_skip_flag is present in the transform unit syntax based on the transform skip enable flag sps_transform_skip_enabled_flag.

[0167] The sps_bdpcm_enabled_flag syntax element may indicate whether BDPCM is enabled based on whether its value is 0 or 1. For example, a value of sps_bdpcm_enabled_flag of 1 indicates that BDPCM is enabled, and in this case, intra_bdpcm_flag (or intra_bdpcm_luma_flag and intra_bdpcm_chroma_flag) may be parsed / signaled via coding unit syntax for an intra-coding unit. Here, the intra_bdpcm_flag syntax element indicates whether BDPCM is applied to the current coding block. If the value of sps_bdpcm_enabled_flag is 0, it indicates that BDPCM is not enabled, and in this case, intra_bdpcm_flag (or intra_bdpcm_luma_flag and intra_bdpcm_chroma_flag) are not parsed / signaled in the coding unit syntax for the intra coding unit. In other words, it is possible to indicate whether intra_bdpcm_flag (or intra_bdpcm_luma_flag and intra_bdpcm_chroma_flag) are present in the coding unit syntax based on the BDPCM enable flag sps_bdpcm_enabled_flag.

[0168] The min_qp_prime_ts_minus4 syntax element indicates the minimum allowed quantization parameter for the transform skip mode. For example, a minimum quantization parameter value (e.g., QpPrimeTsMin) in the transform skip mode is derived based on the min_qp_prime_ts_minus4 syntax element. A quantization parameter used in a scaling process (dequantization process) is derived based on the minimum quantization parameter in the transform skip mode. In addition, a scaling process (dequantization process) is performed on the current block based on the quantization parameter to derive scaled transform coefficients (dequantized transform coefficients), and residual samples of the current block can be derived based on the scaled transform coefficients.

[0169] Furthermore, in the SPS, among the syntax elements related to the transform skip, syntax elements that are dependent on the transform skip enable flag syntax element (e.g., sps_transform_skip_enabled_flag) may be defined. For example, as shown in Tables 6 and 7, in the SPS, the min_qp_prime_ts_minus4 syntax element indicating minimum quantization parameter information for a transform skip block in the transform skip mode and the sps_bdpcm_enabled_flag syntax element indicating whether BDPCM is enabled may be dependent on the value of the transform skip enable flag (e.g., sps_transform_skip_enabled_flag). For example, when the value of the transform skip enable flag (e.g., sps_transform_skip_enabled_flag) is 1, the min_qp_prime_ts_minus4 syntax element and the sps_bdpcm_enabled_flag syntax element may be parsed / signaled. Alternatively, if the value of the transform skip enabled flag (e.g., sps_transform_skip_enabled_flag) is 0, the min_qp_prime_ts_minus4 syntax element and the sps_bdpcm_enabled_flag syntax element are not parsed / signaled.

[0170] In addition, as an embodiment, this document proposes a method for saving transmitted bits by determining whether to parse / signal a syntax element that is dependent on a high-level syntax element related to conversion skip according to the dependent condition. As an example, a method for parsing a high-level syntax element that has a dependency depending on whether conversion skip is available or not according to a conversion skip (available) flag is proposed.

[0171] For example, syntax elements dependent on transform skip-based coding include a transform skip (enabled) flag (e.g., sps_transform_skip_enabled_flag), information on the transform skip application size (e.g., log2_transform_skip_max_size_minus2), minimum quantization parameter information for transform skip (e.g., min_qp_prime_ts_minus4), BDPCM applicability information (e.g., sps_bdpcm_enabled_flag), etc. For example, if the value of the transform skip (enabled) flag is defined as 1, the related flag or information syntax element must be transmitted, whereas if the value of the transform skip (enabled) flag is defined as 0, the above syntax elements except for the transform skip (enabled) flag syntax element are not transmitted.

[0172] That is, a method is proposed for transmitting high level syntax elements that depend on whether or not a transform skip is performed, such as information on the maximum size to which a transform skip can be applied, information on the minimum quantization parameter when a transform skip is performed, and whether or not BDPCM can be applied, depending on the value of a transform skip (available) flag in a high level syntax HLS (e.g., VPS, SPS, PPS, APS, DPS, Slice header, etc.). Furthermore, the proposed method is not limited to only the syntax elements mentioned in this embodiment, but includes all high level syntax elements defined in a high level syntax set that include a transform skip (available) flag and that have a dependency on whether or not a transform skip is performed.

[0173] As described above, syntax elements related to transform skip-based coding can be defined in a high-level syntax set, and can be defined within an SPS (sequence parameter set) as in the example of Table 8. However, maximum block size information for transform skip, which has conventionally been defined in a PPS (picture parameter set), can be newly defined in the SPS to overcome dependencies between HLSs, as shown in Table 8.

[0174] [Table 8]

[0175] Furthermore, for example, the semantics of the syntax elements of the SPS syntax related to the above-mentioned embodiment can be shown as in Table 9 below.

[0176] [Table 9]

[0177] Referring to Tables 8 and 9, syntax elements related to transform skipping can be defined in SPS, including sps_transform_skip_enabled_flag, sps_bdpcm_enabled_flag, min_qp_prime_ts_minus4, and log2_transform_skip_max_size_minus2 syntax elements.

[0178] Here, the sps_transform_skip_enabled_flag, sps_bdpcm_enabled_flag, and min_qp_prime_ts_minus4 syntax elements are described in detail in Tables 6 and 7, and therefore, for the sake of convenience, detailed description thereof will be omitted in this embodiment.

[0179] The log2_transform_skip_max_size_minus2 syntax element indicates the maximum block size used in the transform skip mode. At this time, the log2_transform_skip_max_size_minus2 syntax element can be in the range of 0 to 3. For example, as disclosed in Table 9, the maximum block size (e.g., MaxTsSize) used in the transform skip mode is derived based on a calculation such as 1<<(log2_transform_skip_max_size_minus2+2).

[0180] Furthermore, in the SPS, among the syntax elements related to the transform skip, syntax elements that are dependent on the transform skip enable flag syntax element (e.g., sps_transform_skip_enabled_flag) may be defined. For example, as shown in Tables 8 and 9, the following may be dependent on the value of the transform skip enable flag (e.g., sps_transform_skip_enabled_flag) in the SPS: the sps_bdpcm_enabled_flag syntax element indicating whether BDPCM is enabled, the min_qp_prime_ts_minus4 syntax element indicating minimum quantization parameter information for a transform skip block in the transform skip mode, and the log2_transform_skip_max_size_minus2 syntax element indicating the maximum block size used in the transform skip mode. As an example, if the value of the transform skip enable flag (e.g., sps_transform_skip_enabled_flag) is 1, the sps_bdpcm_enabled_flag, min_qp_prime_ts_minus4, and log2_transform_skip_max_size_minus2 syntax elements may be parsed / signaled. Alternatively, if the value of the transform skip enable flag (e.g., sps_transform_skip_enabled_flag) is 0, the sps_bdpcm_enabled_flag, min_qp_prime_ts_minus4, and log2_transform_skip_max_size_minus2 syntax elements are not parsed / signaled.

[0181] In addition, as an embodiment, this document proposes a method for saving transmitted bits by determining whether to parse / signal syntax elements that are dependent on transform skip-related high-level syntax elements and palette coding-related high-level syntax elements according to the dependency conditions. As an example, this document proposes a method for parsing high-level syntax elements that are dependent on transform skip (available) flags and / or palette coding (available) flags.

[0182] For example, syntax elements dependent on transform skip-based coding include a transform skip (enabled) flag (e.g., sps_transform_skip_enabled_flag), information on the transform skip application size (e.g., log2_transform_skip_max_size_minus2), minimum quantization parameter information for transform skip (e.g., min_qp_prime_ts_minus4), and BDPCM applicability information (e.g., sps_bdpcm_enabled_flag). Also, as described above, since escape values ​​are not converted during palette coding, minimum quantization parameter information for transform skip can be used in quantization. Therefore, a palette coding (enabled) flag (e.g., sps_palette_enabled_flag) and minimum quantization parameter information for transform skip (e.g., min_qp_prime_ts_minus4) can be dependent on palette mode-based coding. As an example, if the value of the transform skip (available) flag or the palette coding (available) flag is defined as 1, the related flag or information syntax element must be transmitted, but if the value of the transform skip (available) flag or the palette coding (available) flag is defined as 0, the above syntax elements except for each flag syntax element are not transmitted.

[0183] That is, we propose a method of transmitting high-level syntax elements dependent on whether transform skip or palette coding is possible, such as information on the maximum size to apply transform skip, information on the minimum quantization parameter when transform skipping, and whether BDPCM is applicable, depending on the value of the transform skip (available) flag and / or palette coding (available) flag in the high-level syntax (e.g., VPS, SPS, PPS, APS, DPS, Slice header, etc.).

[0184] For example, (i) when the transformation skip (available) flag and the palette coding (available) flag are all defined to 1, syntax elements corresponding to the union of syntax elements dependent on the transformation skip (available) flag and the palette coding (available) flag can be parsed. (ii) when the transformation skip (available) flag is defined to 1 and the palette coding (available) flag is 0, syntax elements dependent on the transformation skip (available) flag can be parsed. (iii) when the transformation skip (available) flag is defined to 0 and the palette coding (available) flag is 1, syntax elements dependent on the palette coding (available) flag can be parsed. (iv) when the transformation skip (available) flag and the palette coding (available) flag are all defined to 0, other high-level syntax elements dependent on the two coding tools are not parsed.

[0185] The parsing order of the syntax elements mentioned in this embodiment is not limited to a specific one, and if parsing is determined depending on the dependency between the syntax elements, they are considered to be consistent. Also, the proposed method is not limited to only the syntax elements mentioned in this embodiment, but includes all high-level syntax elements defined in the high-level syntax set that have dependency depending on whether conversion skip or palette coding is possible and include a conversion skip (available) flag and a palette coding (available) flag.

[0186] As mentioned above, syntax elements related to transform skip-based coding and / or palette mode-based coding can be defined in a high-level syntax set and can be defined within an SPS (sequence parameter set) as in the example of Table 10 below.

[0187] [Table 10]

[0188] Furthermore, for example, the semantics of the syntax elements of the SPS syntax related to the above-mentioned embodiment can be shown as in Table 11 below.

[0189] [Table 11]

[0190] Referring to Tables 10 and 11, syntax elements related to transform skip and / or palette coding can be defined in SPS, including sps_transform_skip_enabled_flag, sps_bdpcm_enabled_flag, sps_palette_enabled_flag, and min_qp_prime_ts_minus4 syntax elements.

[0191] Here, the sps_transform_skip_enabled_flag, sps_bdpcm_enabled_flag, and min_qp_prime_ts_minus4 syntax elements are described in detail in Tables 6 to 9, and therefore, for the sake of convenience, detailed description thereof will be omitted in this embodiment.

[0192] The sps_palette_enabled_flag syntax element indicates whether palette coding (i.e., palette prediction mode) is available based on whether its value is 0 or 1. For example, if the value of sps_palette_enabled_flag is 1, it indicates that palette coding is available, and in this case, pred_mode_plt_flag is parsed / signaled via the coding unit syntax. Here, the pred_mode_plt_flag syntax element indicates whether palette mode is available for the current coding unit. If the value of sps_palette_enabled_flag is 0, it indicates that palette coding is not available, and in this case, pred_mode_plt_flag is not parsed / signaled in the coding unit syntax. In other words, it indicates whether pred_mode_plt_flag is present in the coding unit syntax based on the palette coding availability flag sps_palette_enabled_flag.

[0193] Furthermore, in the SPS, among syntax elements related to transform skip and / or palette coding, syntax elements that are dependent on the transform skip enable flag syntax element (e.g., sps_transform_skip_enabled_flag) may be defined. For example, as disclosed in Tables 10 and 11, the sps_bdpcm_enabled_flag syntax element, which indicates whether BDPCM is enabled, may be dependent on the value of the transform skip enable flag (e.g., sps_transform_skip_enabled_flag) in the SPS. For example, if the transform skip enable flag (e.g., sps_transform_skip_enabled_flag) has a value of 1, the sps_bdpcm_enabled_flag syntax element is parsed / signaled. Alternatively, if the transform skip enable flag (e.g., sps_transform_skip_enabled_flag) has a value of 0, the sps_bdpcm_enabled_flag syntax element is not parsed / signaled.

[0194] In addition, in the SPS, a dependent condition can be defined in relation to a palette coding enable flag syntax element (e.g., sps_palette_enabled_flag) among syntax elements related to transform skip and / or palette coding. For example, as disclosed in Tables 10 and 11, in the SPS, a palette coding enable flag syntax element (e.g., sps_palette_enabled_flag) can be parsed / signaled based on the chroma_format_idc syntax element (described later). As an example, if the value of the chroma_format_idc syntax element is 3, the sps_palette_enabled_flag syntax element is parsed / signaled.

[0195] Furthermore, in the SPS, among the syntax elements related to the transform skip and / or palette coding, a syntax element that is dependent on the transform skip enable flag syntax element (e.g., sps_transform_skip_enabled_flag) and / or the palette coding enable flag syntax element (e.g., sps_palette_enabled_flag) may be defined. For example, as shown in Tables 10 and 11, in the SPS, the min_qp_prime_ts_minus4 syntax element indicating minimum quantization parameter information for the transform skip mode may be dependent on the value of the transform skip enable flag (e.g., sps_transform_skip_enabled_flag) and / or the palette coding enable flag syntax element (e.g., sps_palette_enabled_flag). As an example, if the transform skip enabled flag (e.g., sps_transform_skip_enabled_flag) has a value of 1 or the palette coding enabled flag (e.g., sps_palette_enabled_flag) has a value of 1, the min_qp_prime_ts_minus4 syntax element is parsed / signaled.

[0196] Also, as described above, syntax elements related to transform skip-based coding and / or palette mode-based coding can be defined in a high-level syntax set, and can be defined within an SPS (sequence parameter set) as in the example of Table 12. However, maximum block size information for transform skip, which has conventionally been defined in a PPS (picture parameter set), can be newly defined in the SPS to resolve dependencies between HLSs, as shown in Table 12.

[0197] [Table 12]

[0198] Also, for example, the semantics of the syntax elements of the SPS syntax for the above-mentioned embodiments can be shown as in Table 13 below.

[0199] [Table 13]

[0200] Referring to Tables 12 and 13 above, syntax elements related to transform skipping and / or palette coding can be defined in SPS, including sps_transform_skip_enabled_flag, sps_bdpcm_enabled_flag, log2_transform_skip_max_size_minus2, sps_palette_enabled_flag, and min_qp_prime_ts_minus4 syntax elements.

[0201] Here, the sps_transform_skip_enabled_flag, sps_bdpcm_enabled_flag, log2_transform_skip_max_size_minus2, sps_palette_enabled_flag, and min_qp_prime_ts_minus4 syntax elements are described in detail in Tables 6 to 11, and therefore, for the sake of convenience, detailed description thereof will be omitted in this embodiment.

[0202] As disclosed in the embodiments of Tables 12 and 13, in the SPS, syntax elements that are dependent on the transform skip enable flag syntax element (e.g., sps_transform_skip_enabled_flag) among syntax elements related to transform skip and / or palette coding may be defined. For example, as disclosed in Tables 12 and 13, in the SPS, the sps_bdpcm_enabled_flag syntax element indicating whether BDPCM is enabled based on the value of the transform skip enable flag (e.g., sps_transform_skip_enabled_flag) and the log2_transform_skip_max_size_minus2 syntax element indicating the maximum block size used in the transform skip mode may have a dependency. As an example, when the transform skip enable flag (e.g., sps_transform_skip_enabled_flag) is 1, the sps_bdpcm_enabled_flag and log2_transform_skip_max_size_minus2 syntax elements are parsed / signaled. Alternatively, if the value of the transform skip enable flag (e.g., sps_transform_skip_enabled_flag) is 0, the sps_bdpcm_enabled_flag and log2_transform_skip_max_size_minus2 syntax elements are not parsed / signaled.

[0203] Furthermore, in the SPS, among the syntax elements related to the transform skip and / or palette coding, a syntax element that is dependent on the transform skip enable flag syntax element (e.g., sps_transform_skip_enabled_flag) and / or the palette coding enable flag syntax element (e.g., sps_palette_enabled_flag) may be defined. For example, as shown in Tables 12 and 13, in the SPS, the min_qp_prime_ts_minus4 syntax element indicating minimum quantization parameter information for the transform skip mode may be dependent on the value of the transform skip enable flag (e.g., sps_transform_skip_enabled_flag) and / or the palette coding enable flag syntax element (e.g., sps_palette_enabled_flag). As an example, if the transform skip enabled flag (e.g., sps_transform_skip_enabled_flag) has a value of 1 or the palette coding enabled flag (e.g., sps_palette_enabled_flag) has a value of 1, the min_qp_prime_ts_minus4 syntax element is parsed / signaled.

[0204] Meanwhile, a source or coded picture / image includes a luma component array and may also include two chroma component (cb, cr) arrays, i.e., one pixel of the picture / image includes a luma sample and a chroma sample (cb, cr).

[0205] The color format indicates the configuration format of the luma component and the chroma component (cb, cr), and may be called a chroma format. The color format (or chroma format) may be predetermined or may be adaptively signaled. For example, the chroma format may be signaled based on at least one of chroma_format_idc and separate_colour_plane_flag, as shown in Table 14 below.

[0206] [Table 14]

[0207] Referring to Table 14 above, in monochrome sampling there is only one sample array, which is nominally considered the luma array.

[0208] In 4:2:0 sampling, each of the two chroma arrays has half the height and half the width of the luma array.

[0209] In 4:2:2 sampling, each of the two chroma arrays has the same height and half the width of the luma array.

[0210] For 4:4:4 sampling, the following applies depending on the value of separate_colour_plane_flag:

[0211] - If the value of separate_colour_plane_flag is 0, each of the two chroma arrays has the same height and width as the luma array.

[0212] Otherwise, if the value of separate_colour_plane_flag is 1, the three colour planes are processed separately into monochrome sampled pictures.

[0213] SubWidthC and SubHeightC may indicate the ratio between luma samples and chroma samples. For example, if chroma_format_idc is 3, the chroma format is 4:4:4. In this case, if the width of the luma sample block is 16, the width of the chroma sample block may be 16 / SubWidthC. In general, chroma sample-related syntax and bitstreams are parsed only if the chroma array type (e.g., chromaArrayType) is not 0.

[0214] In addition, as an embodiment, this document proposes a method for saving transmitted bits by determining whether syntax elements that have dependencies on transform skip-related high-level syntax elements and palette coding-related high-level syntax elements are parsed / signaled according to the dependency conditions. As an example, this document proposes a method for parsing high-level syntax elements that have dependencies based on the transform skip (available) flag and / or the palette coding (available) flag.

[0215] For example, syntax elements dependent on transform skip-based coding include a transform skip (enabled) flag (e.g., sps_transform_skip_enabled_flag), information on the transform skip application size (e.g., log2_transform_skip_max_size_minus2), minimum quantization parameter information during transform skip (e.g., min_qp_prime_ts_minus4), BDPCM applicability information (e.g., sps_bdpcm_enabled_flag), etc. Also, as described above, since escape values ​​are not converted during palette coding, minimum quantization parameter information for transform skip can be used in performing quantization.

[0216] As described in the above embodiment, when the value of the transform skip (available) flag or the palette coding (available) flag is defined as 1, the related flag or information syntax element must be transmitted, but when the value of the transform skip (available) flag or the palette coding (available) flag is defined as 0, the syntax elements except for each flag syntax element may not be transmitted. That is, a method is proposed for transmitting high-level syntax elements dependent on whether transform skip or palette coding is available, such as minimum quantization parameter information for transform skip or palette coding, whether BDPCM is applicable, etc., according to the values ​​of the transform skip (available) flag and the palette coding (available) flag in a high-level syntax (e.g., VPS, SPS, PPS, APS, DPS, Slice header, etc.).

[0217] For example, (i) when the transformation skip (available) flag and the palette coding (available) flag are all defined to 1, syntax elements corresponding to the union of syntax elements dependent on the transformation skip (available) flag and the palette coding (available) flag can be parsed. (ii) when the transformation skip (available) flag is defined to 1 and the palette coding (available) flag is 0, syntax elements dependent on the transformation skip (available) flag can be parsed. (iii) when the transformation skip (available) flag is defined to 0 and the palette coding (available) flag is 1, syntax elements dependent on the palette coding (available) flag can be parsed. (iv) when the transformation skip (available) flag and the palette coding (available) flag are all defined to 0, other high-level syntax elements dependent on the two coding tools may not be parsed.

[0218] The parsing order of the syntax elements mentioned in this embodiment is not limited to a specific one, and if parsing is determined depending on the dependency between the syntax elements, they are considered to be consistent. In addition, the proposed method is not limited to only the syntax elements mentioned in this embodiment, and can include all high-level syntax elements defined in the high-level syntax set that have dependency depending on whether transformation skip or palette coding is possible and include a transformation skip (available) flag and a palette coding (available) flag.

[0219] As mentioned above, syntax elements related to transform skip-based coding and / or palette mode-based coding can be defined in a high-level syntax set and can be defined within an SPS (sequence parameter set) as in the example of Table 15 below.

[0220] [Table 15]

[0221] Furthermore, for example, the semantics of the syntax elements of the SPS syntax related to the above-mentioned embodiment are shown in Table 16 below.

[0222] [Table 16]

[0223] Referring to Tables 15 and 16, syntax elements related to transform skip and / or palette coding can be defined in SPS, including sps_transform_skip_enabled_flag, sps_bdpcm_enabled_flag, sps_palette_enabled_flag, min_qp_prime_ts_luma_minus4, and min_qp_prime_ts_chroma_minus4 syntax elements.

[0224] Here, the sps_transform_skip_enabled_flag, sps_bdpcm_enabled_flag, and sps_palette_enabled_flag syntax elements have been described in detail in Tables 6 to 11, and therefore, for the sake of convenience, detailed description thereof will be omitted in this embodiment.

[0225] As disclosed in the embodiments of Tables 15 and 16, in the SPS, syntax elements that are dependent on the transform skip enable flag syntax element (e.g., sps_transform_skip_enabled_flag) among syntax elements related to transform skip and / or palette coding may be defined. For example, as disclosed in Tables 15 and 16, in the SPS, the sps_bdpcm_enabled_flag syntax element indicating whether BDPCM is enabled may be dependent on the value of the transform skip enable flag (e.g., sps_transform_skip_enabled_flag). As an example, if the value of the transform skip enable flag (e.g., sps_transform_skip_enabled_flag) is 1, the sps_bdpcm_enabled_flag syntax element is parsed / signaled. Alternatively, if the value of the transform skip enabled flag (e.g., sps_transform_skip_enabled_flag) is 0, the sps_bdpcm_enabled_flag syntax element is not parsed / signaled.

[0226] Furthermore, in the SPS, among syntax elements related to transform skip and / or palette coding, syntax elements that are dependent on a palette coding enable flag syntax element (e.g., sps_palette_enabled_flag) may be defined. For example, as disclosed in Tables 15 and 16, in the SPS, the min_qp_prime_ts_chroma_minus4 syntax element indicating minimum quantization parameter information in the transform skip mode for a chroma component may be dependent on the value of the palette coding enable flag (e.g., sps_palette_enabled_flag). For example, when the value of the palette coding enable flag (e.g., sps_palette_enabled_flag) is 1, the min_qp_prime_ts_chroma_minus4 syntax element is parsed / signaled. Alternatively, if the value of the palette coding enabled flag (e.g., sps_palette_enabled_flag) is 0, the min_qp_prime_ts_chroma_minus4 syntax element is not parsed / signaled.

[0227] Furthermore, in the SPS, among the syntax elements related to transform skip and / or palette coding, a syntax element that is dependent on a transform skip enable flag syntax element (e.g., sps_transform_skip_enabled_flag) and / or a palette coding enable flag syntax element (e.g., sps_palette_enabled_flag) may be defined. For example, as shown in Tables 15 and 16, in the SPS, the min_qp_prime_ts_luma_minus4 syntax element indicating minimum quantization parameter information in a transform skip mode for a luma component may be dependent on the value of the transform skip enable flag (e.g., sps_transform_skip_enabled_flag) and / or the palette coding enable flag syntax element (e.g., sps_palette_enabled_flag). As an example, if the transform skip enabled flag (e.g., sps_transform_skip_enabled_flag) has a value of 1 or the palette coding enabled flag (e.g., sps_palette_enabled_flag) has a value of 1, the min_qp_prime_ts_luma_minus4 syntax element is parsed / signaled.

[0228] In addition, as an embodiment, this document proposes a method for saving transmitted bits by determining whether to parse / signal syntax elements that have dependencies on transform skip-related high-level syntax elements and palette coding-related high-level syntax elements according to the dependency conditions. As an example, this document proposes a method for parsing high-level syntax elements that have dependencies based on the transform skip (available) flag and / or the palette coding (available) flag.

[0229] For example, syntax elements dependent on transform skip-based coding include a transform skip (enabled) flag (e.g., sps_transform_skip_enabled_flag), information on the transform skip application size (e.g., log2_transform_skip_max_size_minus2), minimum quantization parameter information during transform skip (e.g., min_qp_prime_ts_minus4), BDPCM applicability information (e.g., sps_bdpcm_enabled_flag), etc. Also, as described above, since escape values ​​are not converted during palette coding, minimum quantization parameter information for transform skip can be used in performing quantization.

[0230] As described in the above embodiment, when the value of the transform skip (available) flag or the palette coding (available) flag is defined as 1, the related flag or information syntax element must be transmitted, but when the value of the transform skip (available) flag or the palette coding (available) flag is defined as 0, the syntax elements other than the respective flag syntax elements are not transmitted. That is, a method is proposed for transmitting high-level syntax elements dependent on whether transform skip or palette coding is available, such as information on the maximum size to apply transform skip, at least quantization parameter information in transform skip or palette coding, and whether BDPCM is applicable, according to the values ​​of the transform skip (available) flag and the palette coding (available) flag in a high-level syntax (e.g., VPS, SPS, PPS, APS, DPS, Slice header, etc.).

[0231] For example, (i) when the transformation skip (available) flag and the palette coding (available) flag are all defined to 1, syntax elements corresponding to the union of syntax elements dependent on the transformation skip (available) flag and the palette coding (available) flag can be parsed. (ii) when the transformation skip (available) flag is defined to 1 and the palette coding (available) flag is 0, syntax elements dependent on the transformation skip (available) flag are parsed. (iii) when the transformation skip (available) flag is defined to 0 and the palette coding (available) flag is 1, syntax elements dependent on the palette coding (available) flag are parsed. (iv) when the transformation skip (available) flag and the palette coding (available) flag are all defined to 0, other high-level syntax elements dependent on the two coding tools are not parsed.

[0232] The parsing order of the syntax elements mentioned in this embodiment is not limited to a specific one, and if partitioning is determined according to the dependency between the syntax elements, they are considered to be consistent. Also, the proposed method is not limited to only the syntax elements mentioned in this embodiment, but includes all high-level syntax elements defined in the high-level syntax set that have dependency depending on whether transformation skip or palette coding is possible and include a transformation skip (available) flag and a palette coding (available) flag.

[0233] As described above, syntax elements related to transform skip-based coding and / or palette mode-based coding can be defined in a high-level syntax set, and can be defined within an SPS (sequence parameter set) as in the example of Table 17. In this example, information on the transform skip maximum size conventionally defined in a PPS (picture parameter set) can be newly defined in an SPS to overcome dependencies between HLSs, and a method is proposed in which parsing / signaling is performed based on the dependencies of existing syntax elements related to transform skip and palette mode coding.

[0234] [Table 17]

[0235] Furthermore, for example, the semantics of the syntax elements of the SPS syntax related to the above-mentioned embodiment are shown in Table 18 below.

[0236] [Table 18-1]

[0237] [Table 18-2]

[0238] Referring to Tables 17 and 18, syntax elements related to transform skip and / or palette coding can be defined in SPS, including sps_transform_skip_enabled_flag, sps_bdpcm_enabled_flag, log2_transform_skip_max_size_minus2, sps_palette_enabled_flag, min_qp_prime_ts_luma_minus4, and min_qp_prime_ts_chroma_minus4 syntax elements.

[0239] Here, the sps_transform_skip_enabled_flag, sps_bdpcm_enabled_flag, log2_transform_skip_max_size_minus2, sps_palette_enabled_flag, min_qp_prime_ts_luma_minus4, and min_qp_prime_ts_chroma_minus4 syntax elements are described in detail in Tables 6 to 11, so in this embodiment, detailed description will be omitted for convenience of explanation.

[0240] As disclosed in the embodiments of Tables 17 and 18, in the SPS, syntax elements that are dependent on the transform skip enable flag syntax element (e.g., sps_transform_skip_enabled_flag) among syntax elements related to transform skip and / or palette coding may be defined. For example, as disclosed in Tables 17 and 18, in the SPS, the sps_bdpcm_enabled_flag syntax element indicating whether BDPCM is enabled or disabled and the log2_transform_skip_max_size_minus2 syntax element indicating the maximum block size used in the transform skip mode may be dependent based on the value of the transform skip enable flag (e.g., sps_transform_skip_enabled_flag). For example, when the value of the transform skip enable flag (e.g., sps_transform_skip_enabled_flag) is 1, the sps_bdpcm_enabled_flag and log2_transform_skip_max_size_minus2 syntax elements are parsed / signaled. Alternatively, if the value of the transform skip enable flag (e.g., sps_transform_skip_enabled_flag) is 0, the sps_bdpcm_enabled_flag and log2_transform_skip_max_size_minus2 syntax elements are not parsed / signaled. Furthermore, in the SPS, syntax elements that are dependent on the palette coding enable flag syntax element (e.g., sps_palette_enabled_flag) among syntax elements related to transform skip and / or palette coding may be defined. For example, as shown in Tables 17 and 18, the min_qp_prime_ts_chroma_minus4 syntax element indicating minimum quantization parameter information in the transform skip mode for a chroma component may be dependent on the value of the palette coding enable flag (e.g., sps_palette_enabled_flag) in the SPS.As an example, if the value of the palette coding enabled flag (e.g., sps_palette_enabled_flag) is 1, the min_qp_prime_ts_chroma_minus4 syntax element is parsed / signaled, or if the value of the palette coding enabled flag (e.g., sps_palette_enabled_flag) is 0, the min_qp_prime_ts_chroma_minus4 syntax element is not parsed / signaled.

[0241] Furthermore, in the SPS, among the syntax elements related to transform skip and / or palette coding, syntax elements that are dependent on the transform skip enable flag syntax element (e.g., sps_transform_skip_enabled_flag) and / or the palette coding enable flag syntax element (e.g., sps_palette_enabled_flag) may be defined. For example, as shown in Tables 17 and 18, in the SPS, the min_qp_prime_ts_luma_minus4 syntax element indicating minimum quantization parameter information in the transform skip mode for the luma component may be dependent on the value of the transform skip enable flag (e.g., sps_transform_skip_enabled_flag) and / or the palette coding enable flag syntax element (e.g., sps_palette_enabled_flag). As an example, if the value of the transform skip enable flag (e.g., sps_transform_skip_enabled_flag) is 1 or the value of the palette coding enable flag (e.g., sps_palette_enabled_flag) is 1, the min_qp_prime_ts_luma_minus4 syntax element can be parsed / signaled.

[0242] The following drawings are created to illustrate a specific example of the present document. The names of specific devices and specific terms and names (e.g., names of syntax / syntax elements) shown in the drawings are provided for illustrative purposes only, and the technical features of the present document are not limited to the specific names used in the following drawings.

[0243] 10 and 11 illustrate an example of a video / image encoding method and associated components according to embodiment(s) of the present document.

[0244] The method disclosed in FIG. 10 may be performed by the encoding apparatus 200 disclosed in FIG. 2 or FIG. 11. Here, the encoding apparatus 200 disclosed in FIG. 11 is a simplified version of the encoding apparatus 200 disclosed in FIG. 2. Specifically, steps S1000 to S1010 of FIG. 10 are performed by the residual processing unit 230 disclosed in FIG. 2, and step S1020 of FIG. 10 is performed by the entropy encoding unit 240 disclosed in FIG. 2. Also, although not shown, a process of deriving a prediction sample is performed by the prediction unit 220 of the encoding apparatus 200, a process of generating a reconstructed sample and a reconstructed picture for the current block based on the residual sample and the prediction sample for the current block is performed by the adder 250 of the encoding apparatus 200, and a process of encoding prediction information for the current block is performed by the entropy encoding unit 240 of the encoding apparatus 200. 10 is also implemented in the above-described embodiments in this document, so in FIG. 10, detailed descriptions of the contents overlapping with the above-described embodiments will be omitted or simplified.

[0245] As shown in FIG. 10, the encoding apparatus determines whether to apply a transform to a current block based on the transform skip availability information (S1000).

[0246] In one embodiment, an encoding apparatus first determines a prediction mode for a current block and derives prediction samples. For example, the encoding apparatus may determine whether to perform inter prediction or intra prediction on the current block, and may determine a specific inter prediction mode or a specific intra prediction mode based on an RD cost. Alternatively, the encoding apparatus may determine whether to perform prediction on the current block based on a CIIP mode, an IBC mode, a BDPCM mode, a palette mode, or the like. The encoding apparatus may perform prediction according to the determined prediction mode and derive prediction samples for the current block. In this case, various prediction methods disclosed herein, such as inter prediction or intra prediction, may be applied. The encoding apparatus may also generate and encode information (e.g., prediction mode information) related to the prediction applied to the current block.

[0247] The encoding apparatus may derive residual samples by comparing original samples and predicted samples for the current block. The encoding apparatus may derive transform coefficients through a transform process for the residual samples. At this time, the encoding apparatus may determine whether to apply transform to the current block in consideration of coding efficiency. That is, the encoding apparatus may determine whether to apply transform to the residual samples of the current block.

[0248] For example, the encoding apparatus determines whether to apply a transform or a transform skip mode to the current block (residual sample) based on the transform skip availability information.

[0249] As described above, the transform skip availability information is information regarding whether transform skip is available, and can be indicated by the sps_transform_skip_enabled_flag syntax element as disclosed in Tables 6 to 18. For example, if the value of sps_transform_skip_enabled_flag is 1, it indicates that transform skip is available, and in this case, transform_skip_flag is parsed / signaled via the transform unit syntax. Here, the transform_skip_flag syntax element indicates whether a transform can be applied to the associated transform block. If the value of sps_transform_skip_enabled_flag is 0, it indicates that transform skip is not available, and in this case, transform_skip_flag is not parsed / signaled in the transform unit syntax. The transform skip availability information (e.g., sps_transform_skip_enabled_flag) can be included in the SPS and signaled to a decoding device. That is, the transform unit syntax includes a transform skip flag (e.g., transform_skip_flag) based on the transform skip availability information (e.g., sps_transform_skip_enabled_flag) included in the SPS being set to 1. At this time, if the transform skip flag (e.g., transform_skip_flag) included in the transform unit syntax is set to 1, a mode in which no transform is applied to the current block (transform skip mode) is executed. Alternatively, if the transform skip flag (e.g., transform_skip_flag) included in the transform unit syntax is set to 0, a transform is applied to the current block.

[0250] For example, if the value of the transform skip availability information is 1 (i.e., the transform skip availability information indicates that a transform skip is available), the encoding device may determine whether to apply a transform to the current block. That is, the encoding device may generate information (a transform skip flag) regarding whether to apply a transform to the current block based on the value of the transform skip availability information being 1, and signal the transform skip flag via the transform unit syntax. In this case, if a transform is not to be applied to the current block (i.e., in the transform skip mode), the encoding device may generate a transform skip flag with a value of 1 and include it in the transform unit syntax. Alternatively, if a transform is to be applied to the current block, the encoding device may generate a transform skip flag with a value of 0 and include it in the transform unit syntax.

[0251] The encoding device generates residual information for the current block based on whether or not a transformation is applied (S1010).

[0252] In one embodiment, the encoding apparatus derives residual samples of a current block and generates residual information by applying a transform or a transform skip to the residual samples of the current block depending on whether a transform is applied. For example, the encoding apparatus may apply a transform skip mode to residual samples of the current block whose transform skip flag has a value of 1. In this case, the encoding apparatus may derive the residual samples of the current block as transform coefficients. Alternatively, the encoding apparatus may perform a transform on residual samples of the current block whose transform skip flag has a value of 0 to derive transform coefficients. The encoding apparatus may perform a quantization process on the transform coefficients derived by the transform skip or the transform to derive quantized transform coefficients. The encoding apparatus may generate residual information based on the quantized transform coefficients.

[0253] Here, the residual information is information about quantized transform coefficients as information generated by the transform and / or quantization procedures, and includes, for example, value information, position information, transform technique, transform kernel, quantization parameter, etc. of the quantized transform coefficients.

[0254] The encoding device encodes the image information (or video information) (S1020).

[0255] Here, the video information includes the residual information, information about the prediction used to derive the prediction samples (e.g., prediction mode information), and information about the transform skip, e.g., transform skip availability information and transform skip flag information. That is, the video information includes various information derived during the encoding process and is encoded including such various information.

[0256] In addition, the video information includes various information according to the embodiments described above in this document, including information disclosed in at least one of Table 1 through FIG.

[0257] For example, the video information includes a Sequence Parameter Set (SPS). The SPS includes transform skip-related information, palette coding-related information, etc. For example, the transform skip-related information includes transform skip availability information (e.g., sps_transform_skip_enabled_flag), BDPCM availability information (e.g., sps_bdpcm_enabled_flag), information about the maximum block size used in the transform skip mode (e.g., log2_transform_skip_max_size_minus2), minimum quantization parameter information related to the minimum allowed quantization parameter for the transform skip mode (e.g., min_qp_prime_ts_minus4), etc. Also, for example, information about palette coding includes palette coding availability information (e.g., sps_palette_enabled_flag), minimum quantization parameter information related to the minimum allowed quantization parameter for the transform skip mode (e.g., min_qp_prime_ts_minus4), etc.

[0258] Also, for example, among the information regarding the transform skip and / or palette coding included in the SPS as described above, information that is dependent on the transform skip availability information (e.g., sps_transform_skip_enabled_flag) can be defined.

[0259] As an example, the SPS may be configured to parse / signal BDPCM availability flag information (e.g., sps_bdpcm_enabled_flag) regarding whether BDPCM is available based on the value of transform skip availability information (e.g., sps_transform_skip_enabled_flag). In this case, if the value of the transform skip availability flag information (e.g., sps_transform_skip_enabled_flag) is 1, the BDPCM availability flag information (e.g., sps_bdpcm_enabled_flag) is included in the SPS, and the information (e.g., sps_bdpcm_enabled_flag) may be parsed / signaled from the SPS. Alternatively, if the value of the transform skip availability flag information (e.g., sps_transform_skip_enabled_flag) is 0, the BDPCM availability flag information (e.g., sps_bdpcm_enabled_flag) is not parsed / signaled from the SPS.

[0260] Furthermore, BDPCM flag information (e.g., intra_bdpcm_flag) regarding whether BDPCM is applied to the current block can be parsed / signaled via the coding unit syntax based on the value of BDPCM availability flag information (e.g., sps_bdpcm_enabled_flag) in the SPS. In this case, if the value of the BDPCM availability flag information (e.g., sps_bdpcm_enabled_flag) is 1, the BDPCM flag information (e.g., intra_bdpcm_flag) is included in the coding unit syntax, and the information (e.g., intra_bdpcm_flag) is parsed / signaled from the coding unit syntax. Alternatively, if the value of the BDPCM availability flag information (e.g., sps_bdpcm_enabled_flag) is 0, the BDPCM flag information (e.g., intra_bdpcm_flag) is not parsed / signaled from the coding unit syntax.

[0261] Alternatively, as an example, the SPS may be configured to parse / signal information (e.g., log2_transform_skip_max_size_minus2) regarding the maximum block size used in the transform skip mode based on the value of transform skip availability information (e.g., sps_transform_skip_enabled_flag). In this case, if the value of the transform skip availability flag information (e.g., sps_transform_skip_enabled_flag) is 1, information (e.g., log2_transform_skip_max_size_minus2) regarding the maximum block size used in the transform skip mode is included in the SPS, and the information (e.g., log2_transform_skip_max_size_minus2) is parsed / signaled from the SPS. Alternatively, if the value of the transform skip enable flag information (e.g., sps_transform_skip_enabled_flag) is 0, information about the maximum block size used in transform skip mode (e.g., log2_transform_skip_max_size_minus2) is not parsed / signaled from the SPS.

[0262] Alternatively, as an example, transform skip flag information (e.g., transform_skip_flag) regarding whether to apply a transform skip to a current block may be parsed / signaled via the transform unit syntax based on the value of transform skip enable flag information (e.g., sps_transform_skip_enabled_flag) defined in the SPS. In this case, if the value of the transform skip enable flag information (e.g., sps_transform_skip_enabled_flag) is 1, the transform skip flag information (e.g., transform_skip_flag) is included in the transform unit syntax, and the information (e.g., transform_skip_flag) is parsed / signaled from the transform unit syntax. Alternatively, if the value of the transform skip enable flag information (e.g., sps_transform_skip_enabled_flag) is 0, the transform skip flag information (e.g., transform_skip_flag) is not parsed / signaled from the transform unit syntax.

[0263] Also, for example, as described above, information related to transform skip and / or palette coding included in the SPS may be defined as information that is dependent on palette coding availability information (e.g., sps_palette_enabled_flag) indicating whether palette coding is available. As an example, palette prediction mode flag information (e.g., pred_mode_plt_flag) indicating whether palette coding (palette prediction mode) is applied to a current block may be parsed / signaled via a coding unit syntax based on the value of the palette coding availability information (e.g., sps_palette_enabled_flag) defined in the SPS. In this case, if the value of the palette coding availability information (e.g., sps_palette_enabled_flag) is 1, palette prediction mode flag information (e.g., pred_mode_plt_flag) is included in the coding unit syntax, and the information (e.g., pred_mode_plt_flag) is parsed / signaled from the coding unit syntax. Alternatively, if the value of palette coding enable information (e.g., sps_palette_enabled_flag) is 0, the palette prediction mode flag information (e.g., pred_mode_plt_flag) is not parsed / signaled from the coding unit syntax.

[0264] In addition, for example, among the information regarding transform skip and / or palette coding included in the SPS as described above, it is possible to define information that is dependent on transform skip availability information (e.g., sps_transform_skip_enabled_flag) and / or palette coding availability information (e.g., sps_palette_enabled_flag).

[0265] For example, minimum quantization parameter information (e.g., min_qp_prime_ts_minus4) associated with the minimum allowable quantization parameter for a transform skip mode may be parsed / signaled based on at least one of transform skip availability information (e.g., sps_transform_skip_enabled_flag) and / or palette coding availability information (e.g., sps_palette_enabled_flag) in the SPS. In other words, minimum quantization parameter information (e.g., min_qp_prime_ts_minus4) is included in the SPS based on the condition that the value of the transform skip availability information (e.g., sps_transform_skip_enabled_flag) is 1 or the value of the palette coding availability information (e.g., sps_palette_enabled_flag) is 1, and minimum quantization parameter information (e.g., min_qp_prime_ts_minus4) may be parsed / signaled only if the above condition is satisfied.

[0266] Here, the minimum quantization parameter information (eg, min_qp_prime_ts_minus4) is information on the minimum allowable quantization parameter for the transform skip mode as described above, and the quantization parameter for the current block can be derived based on this information.

[0267] For example, when a transform skip mode is applied to the current block, a quantization parameter for the current block can be derived based on at least quantization parameter information (e.g., min_qp_prime_ts_minus4), and a quantization process can be performed based on the quantization parameter to derive quantized transform coefficients.

[0268] Alternatively, for example, when a palette coding mode is applied to the current block, a quantization parameter for the escape value of the current block can be derived based on minimum quantization parameter information (e.g., min_qp_prime_ts_minus4). In this case, a quantized escape value (e.g., palette_escape_val) can be derived by applying the quantization parameter to the escape value of the current block. The process of applying the palette coding mode is performed as disclosed in Tables 4 and 5.

[0269] Video information including the various information described above is encoded and output in the form of a bitstream. The bitstream is transmitted to a decoding device via a network or a (digital) storage medium. Here, the network includes a broadcasting network and / or a communication network, and the digital storage medium includes various storage media such as USB, SD, CD, DVD, Blu-ray, HDD, SSD, etc.

[0270] 12 and 13 show an example of a video / image decoding method and associated components according to embodiment(s) of the present document.

[0271] The method disclosed in FIG. 12 may be performed by the decoding apparatus 300 disclosed in FIG. 3 or FIG. 13. Here, the decoding apparatus 300 disclosed in FIG. 13 is a simplified version of the decoding apparatus 300 disclosed in FIG. 3. Specifically, step S1200 of FIG. 12 is performed by the entropy decoding unit 310 disclosed in FIG. 3, steps S1210 to S1220 of FIG. 12 are performed by the residual processing unit 320 disclosed in FIG. 3, and step S1230 of FIG. 12 is performed by the adder 340 disclosed in FIG. 3. Also, although not shown, the process of receiving prediction information for the current block is performed by the entropy decoding unit 310 of the decoding apparatus 300, and the process of deriving prediction samples for the current block is performed by the prediction unit 330 of the decoding apparatus 300. Also, the method disclosed in FIG. 12 may be performed including the embodiments described above in this document. Therefore, in FIG. 12, detailed explanations of the contents that overlap with the above-described embodiment will be omitted or simplified.

[0272] As shown in FIG. 12, a decoding device receives image information (or video information) from a bitstream (S1200).

[0273] In one embodiment, a decoding device parses a bitstream to derive information (e.g., video / image information) necessary for image restoration (or picture restoration). The image information includes residual information, such as value information of quantized transform coefficients, position information, a transform technique, a transform kernel, and a quantization parameter. The image information also includes prediction information (e.g., prediction mode information). The image information also includes information about the transform skip, such as transform skip availability information and transform skip flag information. That is, the image information includes various information necessary for the decoding process and can be decoded based on a coding method such as Exponential-Golomb coding, CAVLC, or CABAC.

[0274] Additionally, the video information may include various information according to the embodiment(s) previously described herein, including information disclosed in at least one of Table 1 through FIG. 18 previously described.

[0275] For example, the video information includes a Sequence Parameter Set (SPS). The SPS includes transform skip-related information, palette coding-related information, etc. For example, the transform skip-related information includes transform skip availability information (e.g., sps_transform_skip_enabled_flag), BDPCM availability information (e.g., sps_bdpcm_enabled_flag), information on the maximum block size used in the transform skip mode (e.g., log2_transform_skip_max_size_minus2), minimum quantization parameter information related to the minimum allowable quantization parameter for the transform skip mode (e.g., min_qp_prime_ts_minus4), etc. Also, for example, the palette coding-related information includes palette coding availability information (e.g., sps_palette_enabled_flag), minimum quantization parameter information related to the minimum allowable quantization parameter for the transform skip mode (e.g., min_qp_prime_ts_minus4), etc.

[0276] Also, for example, as described above, among the information regarding the transform skip and / or palette coding included in the SPS, information that is dependent on the transform skip availability information (e.g., sps_transform_skip_enabled_flag) can be defined.

[0277] As an example, the SPS may be configured to parse / signal BDPCM availability flag information (e.g., sps_bdpcm_enabled_flag) indicating whether BDPCM is available based on the value of transform skip availability information (e.g., sps_transform_skip_enabled_flag). In this case, if the value of the transform skip availability flag information (e.g., sps_transform_skip_enabled_flag) is 1, the BDPCM availability flag information (e.g., sps_bdpcm_enabled_flag) is included in the SPS, and the information (e.g., sps_bdpcm_enabled_flag) is parsed / signaled from the SPS. Alternatively, if the value of the transform skip availability flag information (e.g., sps_transform_skip_enabled_flag) is 0, the BDPCM availability flag information (e.g., sps_bdpcm_enabled_flag) is not parsed / signaled from the SPS.

[0278] Furthermore, BDPCM flag information (e.g., intra_bdpcm_flag) regarding whether BDPCM is applied to the current block can be parsed / signaled via the coding unit syntax based on the value of BDPCM availability flag information (e.g., sps_bdpcm_enabled_flag) in the SPS. In this case, if the value of the BDPCM availability flag information (e.g., sps_bdpcm_enabled_flag) is 1, the BDPCM flag information (e.g., intra_bdpcm_flag) is included in the coding unit syntax, and the information (e.g., intra_bdpcm_flag) is parsed / signaled from the coding unit syntax. Alternatively, if the value of the BDPCM availability flag information (e.g., sps_bdpcm_enabled_flag) is 0, the BDPCM flag information (e.g., intra_bdpcm_flag) is not parsed / signaled from the coding unit syntax.

[0279] Alternatively, as an example, the SPS may be configured to parse / signal information (e.g., log2_transform_skip_max_size_minus2) regarding the maximum block size used in the transform skip mode based on the value of transform skip availability information (e.g., sps_transform_skip_enabled_flag). In this case, if the value of the transform skip availability flag information (e.g., sps_transform_skip_enabled_flag) is 1, information (e.g., log2_transform_skip_max_size_minus2) regarding the maximum block size used in the transform skip mode is included in the SPS, and the information (e.g., log2_transform_skip_max_size_minus2) is parsed / signaled from the SPS. Alternatively, if the value of the transform skip enable flag information (e.g., sps_transform_skip_enabled_flag) is 0, information about the maximum block size used in transform skip mode (e.g., log2_transform_skip_max_size_minus2) is not parsed / signaled from the SPS.

[0280] Alternatively, as an example, transform skip flag information (e.g., transform_skip_flag) regarding whether to apply a transform skip to a current block may be parsed / signaled via the transform unit syntax based on the value of transform skip enable flag information (e.g., sps_transform_skip_enabled_flag) defined in the SPS. In this case, if the value of the transform skip enable flag information (e.g., sps_transform_skip_enabled_flag) is 1, the transform skip flag information (e.g., transform_skip_flag) is included in the transform unit syntax, and the information (e.g., transform_skip_flag) is parsed / signaled from the transform unit syntax. Alternatively, if the value of the transform skip enable flag information (e.g., sps_transform_skip_enabled_flag) is 0, the transform skip flag information (e.g., transform_skip_flag) is not parsed / signaled from the transform unit syntax.

[0281] Also, for example, as described above, information related to transform skip and / or palette coding included in the SPS may be defined that is dependent on palette coding availability information (e.g., sps_palette_enabled_flag) regarding whether palette coding is available. As an example, palette prediction mode flag information (e.g., pred_mode_plt_flag) regarding whether palette coding (palette prediction mode) is applied to a current block may be parsed / signaled via a coding unit syntax based on the value of the palette coding availability information (e.g., sps_palette_enabled_flag) defined in the SPS. In this case, if the value of the palette coding availability information (e.g., sps_palette_enabled_flag) is 1, palette prediction mode flag information (e.g., pred_mode_plt_flag) is included in the coding unit syntax, and the information (e.g., pred_mode_plt_flag) is parsed / signaled from the coding unit syntax. Alternatively, if the value of palette coding enable information (e.g., sps_palette_enabled_flag) is 0, the palette prediction mode flag information (e.g., pred_mode_plt_flag) is not parsed / signaled from the coding unit syntax.

[0282] Also, for example, as described above, among the information regarding transform skip and / or palette coding included in the SPS, it is possible to define information that is dependent on transform skip availability information (e.g., sps_transform_skip_enabled_flag) and / or palette coding availability information (e.g., sps_palette_enabled_flag).

[0283] As an example, minimum quantization parameter information (e.g., min_qp_prime_ts_minus4) regarding the minimum allowed quantization parameter for the transform skip mode may be parsed / signaled based on at least one of transform skip availability information (e.g., sps_transform_skip_enabled_flag) and / or palette coding availability information (e.g., sps_palette_enabled_flag) in the SPS. That is, based on the condition that the value of the transform skip availability information (e.g., sps_transform_skip_enabled_flag) is 1 or the value of the palette coding availability information (e.g., sps_palette_enabled_flag) is 1, the minimum quantization parameter information (e.g., min_qp_prime_ts_minus4) is included in the SPS and only if the above condition is satisfied, the minimum quantization parameter information (e.g., min_qp_prime_ts_minus4) may be parsed / signaled.

[0284] Here, the minimum quantization parameter information (eg, min_qp_prime_ts_minus4) is information about the minimum allowable quantization parameter for the transform skip mode as described above, and the quantization parameter for the current block can be derived based on this information.

[0285] For example, when a transform skip mode is applied to a current block, a quantization parameter for the current block is derived based on minimum quantization parameter information (e.g., min_qp_prime_ts_minus4), and a dequantization process (scaling process) is performed based on the quantization parameter to derive dequantized transform coefficients (scaled transform coefficients). Residual samples of the current block can be derived based on the dequantized transform coefficients.

[0286] Alternatively, for example, when a palette coding mode is applied to the current block, a quantization parameter for the escape value of the current block can be derived based on minimum quantization parameter information (e.g., min_qp_prime_ts_minus4). In this case, an escape value of the current block can be derived by performing inverse quantization (scaling process) based on the quantization parameter. A reconstructed sample of the current block can be generated based on the escape value. The process of applying the palette coding mode is performed as disclosed in Tables 4 and 5.

[0287] The decoding device determines whether to apply a transform to the current block based on the transform skip availability information (S1210).

[0288] In one embodiment, when receiving video information including transform skip availability information, the decoding device determines whether to apply a transform or a transform skip mode to a current block based on the transform skip availability information.

[0289] As described above, the transform skip availability information is information regarding whether transform skip is available, and can be indicated by the sps_transform_skip_enabled_flag syntax element as disclosed in Tables 6 to 18. For example, if the value of sps_transform_skip_enabled_flag is 1, it indicates that transform skip is available, and in this case, transform_skip_flag is parsed / signaled via the transform unit syntax. Here, the transform_skip_flag syntax element indicates whether a transform can be applied to the associated transform block. If the value of sps_transform_skip_enabled_flag is 0, it indicates that transform skip is not available, and in this case, transform_skip_flag is not parsed / signaled in the transform unit syntax. The transform skip availability information (e.g., sps_transform_skip_enabled_flag) is included in the SPS and signaled from the encoding device to the decoding device. That is, the transform unit syntax includes a transform skip flag (e.g., transform_skip_flag) based on the transform skip availability information (e.g., sps_transform_skip_enabled_flag) included in the SPS being set to 1. At this time, if the transform skip flag (e.g., transform_skip_flag) included in the transform unit syntax is set to 1, a mode in which no transform is applied to the current block (transform skip mode) is performed. Alternatively, if the transform skip flag (e.g., transform_skip_flag) included in the transform unit syntax is set to 0, a transform is applied to the current block.

[0290] For example, if the value of the transform skip availability information is 1 (ie, for the transform skip availability information indicating that the transform skip is available), the decoding device can determine whether to apply the transform to the current block.

[0291] The decoding apparatus derives residual samples based on the transform applicability and residual information (S1220).

[0292] For example, a decoding device receives video information including residual information. The residual information includes, as described above, information such as value information, position information, transform technique, transform kernel, and quantization parameter of quantized transform coefficients. The decoding device may derive quantized transform coefficients for a current block based on the quantized transform coefficient information included in the residual information, derive transform coefficients based on the quantized transform coefficients, and derive residual samples based on the transform coefficients.

[0293] For example, if the value of the transform skip availability information is 1 (i.e., for the transform skip availability information indicating that a transform skip is available), the decoding device may obtain information (transform skip flag) regarding whether to apply a transform to the current block from the transform unit syntax. In this case, the decoding device may derive residual samples based on the transform skip flag information. For example, a transform skip mode may be applied to a current block whose transform skip flag value is 1, in which case the decoding device may derive transform coefficients as residual samples of the current block. Alternatively, a transform may be applied to a current block whose transform skip flag value is 0, in which case the decoding device may perform an inverse transform on the transform coefficients to derive residual samples of the current block.

[0294] Furthermore, for a current block whose transform skip flag value is 1 (i.e., transform skip mode), the decoding device may derive a quantization parameter used in the inverse quantization process based on the minimum quantization parameter information, perform an inverse quantization process based on the quantization parameter, derive inverse quantized transform coefficients, and derive residual samples based on the inverse quantized transform coefficients.

[0295] Here, as described above, the minimum quantization parameter information is information regarding the minimum allowable quantization parameter for the transform skip mode, and is included in the video information (e.g., SPS) based on at least one of the transform skip availability information (e.g., sps_transform_skip_enabled_flag) and / or the palette coding availability information (e.g., sps_palette_enabled_flag). For example, the minimum quantization parameter information (e.g., min_qp_prime_ts_minus4) is included in the SPS based on the condition that the transform skip availability information (e.g., sps_transform_skip_enabled_flag) has a value of 1 or the palette coding availability information (e.g., sps_palette_enabled_flag) has a value of 1. That is, the minimum quantization parameter information (e.g., min_qp_prime_ts_minus4) can be parsed / signaled only when the above conditions are satisfied.

[0296] The decoding device generates reconstruction samples based on the residual samples (S1230).

[0297] In one embodiment, a decoding apparatus may determine whether to perform inter-prediction or intra-prediction on a current block based on prediction information (e.g., prediction mode information) included in video information, and derive a predicted sample for the current block by performing prediction based on the determination. The decoding apparatus then generates a reconstructed sample based on the predicted sample and the residual sample. In this case, the decoding apparatus may directly use the predicted sample as a reconstructed sample depending on the prediction mode, or may generate a reconstructed sample by adding the residual sample to the predicted sample. Furthermore, a reconstructed block or a reconstructed picture may be derived based on the reconstructed sample. As described above, the decoding apparatus may then apply in-loop filtering procedures, such as deblocking filtering and / or SAO procedures, to the reconstructed picture to improve subjective / objective image quality as needed.

[0298] In the above-described embodiments, the methods are described with reference to flow charts as a series of steps or blocks, but the embodiments are not limited to the order of the steps, and certain steps may occur in a different order or simultaneously with other steps than those described. Furthermore, those skilled in the art will understand that the steps shown in the flow charts are not exclusive, and other steps may be included, or one or more steps in the flow charts may be deleted without affecting the scope of the embodiments herein.

[0299] The methods according to the embodiments of the present document described above can be implemented in software form, and the encoding device and / or decoding device according to the present document can be included in devices that perform video processing, such as TVs, computers, smartphones, set-top boxes, and display devices.

[0300] In this document, when an embodiment is implemented in software, the method described above may be implemented with modules (processes, functions, etc.) that perform the functions described above. The modules may be stored in memory and executed by a processor. The memory may be internal or external to the processor and may be coupled to the processor in various well-known ways. The processor may include an application-specific integrated circuit (ASIC), other chipsets, logic circuits, and / or data processing devices. The memory may include read-only memory (ROM), random access memory (RAM), flash memory, a memory card, a storage medium, and / or other storage devices. That is, the embodiments described herein may be implemented and executed on a processor, microprocessor, controller, or chip. For example, the functional units illustrated in each drawing may be implemented and executed on a computer, processor, microprocessor, controller, or chip. In this case, information (e.g., information on instructions) or algorithms for implementation may be stored on a digital storage medium.

[0301] In addition, the decoding device and encoding device to which this document is applied may be included in a multimedia broadcast transmitting / receiving device, a mobile communication terminal, a home cinema video device, a digital cinema video device, a surveillance camera, a video interaction device, a real-time communication device such as video communication, a mobile streaming device, a storage medium, a camcorder, a custom video (VoD) service providing device, an over-the-top (OTT) video (over-the-top) device, an internet streaming service providing device, a three-dimensional (3D) video device, a virtual reality (VR) device, an augmented reality (AR) device, an image telephone video device, a vehicle terminal (e.g., a vehicle terminal (including an autonomous vehicle), an airplane terminal, a ship terminal, etc.), a medical video device, etc., and may be used to process a video signal or a data signal. For example, over-the-top (OTT) video (over-the-top) device may include a console, a Blu-ray player, an internet-connected TV, a home theater system, a smartphone, a tablet PC, a digital video recorder (DVR), etc.

[0302] In addition, a processing method to which the embodiment(s) of this document is applied may be produced in the form of a computer-executable program and stored in a computer-readable recording medium. Multimedia data having a data structure according to the embodiment(s) of this document may also be stored in a computer-readable recording medium. The computer-readable recording medium includes all types of storage devices and distributed storage devices in which computer-readable data is stored. Examples of the computer-readable recording medium include Blu-ray Discs (BDs), Universal Serial Buses (USBs), ROMs, PROMs, EPROMs, EEPROMs, RAMs, CD-ROMs, magnetic tapes, floppy disks, and optical data storage devices. The computer-readable recording medium also includes media embodied in the form of carrier waves (e.g., transmission via the Internet). A bitstream generated by the encoding method may be stored in a computer-readable recording medium or transmitted via a wired or wireless communication network.

[0303] Furthermore, the embodiment(s) of this document may be embodied in a computer program product by program code, which may be executed by a computer in accordance with the embodiment(s) of this document, and which may be stored on a computer-readable carrier.

[0304] FIG. 14 illustrates an example of a content streaming system to which the embodiments disclosed herein can be applied.

[0305] As shown in FIG. 14, the content streaming system applied to the embodiment of this document mainly includes an encoding server, a streaming server, a web server, a media repository, a user device, and a multimedia input device.

[0306] The encoding server compresses content input from a multimedia input device such as a smartphone, camera, camcorder, etc. into digital data to generate a bitstream and transmits the bitstream to the streaming server. As another example, if a multimedia input device such as a smartphone, camera, camcorder, etc. directly generates a bitstream, the encoding server may be omitted.

[0307] The bitstream may be generated by an encoding method or a bitstream generation method applied to an embodiment of this document, and the streaming server may temporarily store the bitstream during the process of transmitting or receiving the bitstream.

[0308] The streaming server transmits multimedia data to a user device based on a user request via a web server, and the web server acts as an intermediary to inform the user of available services. When a user requests a desired service from the web server, the web server transmits the request to the streaming server, which then transmits the multimedia data to the user. In this case, the content streaming system may include a separate control server, which controls commands and responses between devices in the content streaming system.

[0309] The streaming server can receive content from a media repository and / or an encoding server. For example, if content is received from the encoding server, the content can be received in real time. In this case, the streaming server can store the bitstream for a certain period of time to provide a smooth streaming service.

[0310] Examples of the user devices include mobile phones, smartphones, laptop computers, digital broadcasting terminals, personal digital assistants (PDAs), portable multimedia players (PMPs), navigation systems, slate PCs, tablet PCs, ultrabooks, wearable devices (e.g., smartwatches, smart glasses, head-mounted displays (HMDs)), digital TVs, desktop computers, and digital signs.

[0311] Each server in the content streaming system can be operated as a distributed server, in which case data received by each server can be processed in a distributed manner.

[0312] The claims described herein may be combined in various ways. For example, the technical features of the method claims herein may be combined and embodied in an apparatus, and the technical features of the apparatus claims herein may be combined and embodied in a method. Furthermore, the technical features of the method claims herein and the technical features of the apparatus claims herein may be combined and embodied in an apparatus, and the technical features of the method claims herein and the technical features of the apparatus claims herein may be combined and embodied in a method.

Claims

1. A video decoding method performed by a decoding device, obtaining video information including prediction mode information, residual information, and transform skip availability information from a bitstream; obtaining a transformation skip flag based on the value of the transformation skip availability information; deriving a prediction sample for a current block based on the prediction mode information; deriving a residual sample for the current block based on the transform skip flag and the residual information; generating reconstructed samples based on the predicted samples and the residual samples; The image information includes palette coding availability information, The video information further includes minimum quantization parameter information related to a minimum allowed quantization parameter for a transform skip mode based on at least one of the transform skip availability information and the palette coding availability information; the minimum quantization parameter information is included in the video information under a condition that the value of the transform skip availability information is 1 or the value of the palette coding availability information is 1; The minimum quantization parameter information is not included in the video information under a condition that the value of the transform skip availability information and the value of the palette coding availability information are both 0; a value of the transform skip flag equal to 1 is associated with the transform skip mode, which indicates that no transform is applied to the current block; deriving a quantization parameter for the current block based on the minimum quantization parameter information based on the value of the transform skip flag being equal to 1; and deriving the residual sample based on the quantization parameter; A method comprising: deriving a quantization parameter for the current block based on the minimum quantization parameter information; and deriving an escape value based on the quantization parameter based on if a palette mode is applied to the current block.

2. A video encoding method performed by an encoding device, deriving a prediction mode for a current block; generating information about the prediction mode; generating a transform skip flag based on the transform skip availability information; generating residual information based on the transformation skip flag; encoding video information including the information on the prediction mode, the transform skip flag, the transform skip availability information, and the residual information; The image information includes palette coding availability information, The video information further includes minimum quantization parameter information related to a minimum allowed quantization parameter for a transform skip mode based on at least one of the transform skip availability information and the palette coding availability information; the minimum quantization parameter information is included in the video information under a condition that the value of the transform skip availability information is 1 or the value of the palette coding availability information is 1; The minimum quantization parameter information is not included in the video information under a condition that the value of the transform skip availability information and the value of the palette coding availability information are both 0; a quantization parameter for the current block is derived based on the minimum quantization parameter information based on whether the transform skip mode is applied to the current block or whether a palette mode is applied to the current block; a value of the transform skip flag equal to 1 is associated with the transform skip mode, which indicates that no transform is applied to the current block; A method, wherein based on the value of the transform skip flag being equal to 1, the residual information is generated for the current block to which the transform is not applied.

3. A method for transmitting data for video, comprising: obtaining a bitstream, The bitstream comprises: deriving a prediction mode for a current block; generating information about the prediction mode; generating a transform skip flag based on the transform skip availability information; generating residual information based on the transformation skip flag; encoding video information including the information regarding the prediction mode, the transform skip flag, the transform skip availability information, and the residual information; transmitting the data including the bitstream; The image information includes palette coding availability information, The video information further includes minimum quantization parameter information related to a minimum allowed quantization parameter for a transform skip mode based on at least one of the transform skip availability information and the palette coding availability information; the minimum quantization parameter information is included in the video information under a condition that the value of the transform skip availability information is 1 or the value of the palette coding availability information is 1; The minimum quantization parameter information is not included in the video information under a condition that the value of the transform skip availability information and the value of the palette coding availability information are both 0; a quantization parameter for the current block is derived based on the minimum quantization parameter information based on whether the transform skip mode is applied to the current block or whether a palette mode is applied to the current block; a value of the transform skip flag equal to 1 is associated with the transform skip mode, which indicates that no transform is applied to the current block; A transmission method, wherein, based on the value of the transform skip flag being equal to 1, the residual information is generated for the current block to which the transform is not applied.

Images