Decoding and encoding apparatus and apparatus for transmitting data for image

Abstract

A decoding and encoding apparatus and an apparatus for transmitting data for an image are disclosed. According to the present disclosure, a method for decoding an image by a decoding device may signal picture segmentation-related information based on a flag indicating whether sub-picture information exists and a flag indicating whether sub-pictures each contain a single slice.

Description

[0001] This application is a divisional application of the invention patent application with the original application number 202080093823.7 (International application number: PCT / KR2020 / 017035, application date: November 27, 2020, invention name: Image decoding method and device therefor). Technical Field

[0002] The present disclosure relates to an image decoding method and a device used therefor. Background Art

[0003] Recently, in various fields, the demand for high-resolution, high-quality images such as high-definition (HD) images and ultra-high-definition (UHD) images is growing. Because image data has high resolution and high quality, the amount of information or bits to be transmitted increases relative to conventional image data. Therefore, when image data is transmitted using a medium such as a conventional wired / wireless broadband line or stored using an existing storage medium, its transmission cost and storage cost increase.

[0004] Therefore, there is a need for efficient image compression technology that can effectively transmit, store and reproduce information of high-resolution and high-quality images. Summary of the invention

[0005] Technical issues

[0006] The present disclosure provides a method and an apparatus for improving image coding efficiency.

[0007] The present disclosure also provides a method and apparatus for signaling segmentation information of a picture.

[0008] The present disclosure also provides a method and device for decoding a current picture based on segmentation information of the current picture.

[0009] Technical Solution

[0010] On the one hand, a method for image decoding performed by a decoding device is provided. The method includes: obtaining image information including segmentation information and residual information of a current picture from a bitstream; deriving a segmentation structure of the current picture including at least one slice based on the segmentation information of the current picture; and decoding the current picture based on the segmentation structure, wherein decoding the current picture includes deriving residual samples of the current block based on residual information of the current block included in the at least one slice; and reconstructing the current picture based on the residual samples, wherein the segmentation information includes a first flag related to the presence of sub-picture information and a second flag related to whether each sub-picture in the current picture includes only one slice, and wherein the value of the first flag is equal to 0, and the value of the second flag is equal to 1.

[0011] On the other hand, an image encoding method performed by an encoding device is provided. The method includes: dividing a current picture into at least one slice; generating segmentation information of the current picture based on the at least one slice; deriving residual samples of a current block included in the at least one slice; generating residual information of the current block based on the residual samples; and encoding image information of the current picture including the segmentation information and the residual information, wherein the segmentation information includes a first flag related to the presence of sub-picture information and a second flag related to whether each sub-picture in the current picture includes only one slice, and wherein the value of the first flag is equal to 0, and the value of the second flag is equal to 1.

[0012] In another aspect, a non-transitory computer-readable storage medium storing a bitstream is provided, the bitstream including image information causing an image decoding method to be performed. The image decoding method includes: obtaining image information including segmentation information and residual information of a current picture from a bitstream; deriving a segmentation structure of a current picture including at least one slice based on the segmentation information of the current picture; and decoding the current picture based on the segmentation structure, wherein decoding the current picture includes deriving residual samples of the current block based on residual information of the current block included in the at least one slice; and reconstructing the current picture based on the residual samples, wherein the segmentation information includes a first flag related to the presence of sub-picture information and a second flag related to whether each sub-picture in the current picture includes only one slice, and wherein the value of the first flag is equal to 0, and the value of the second flag is equal to 1.

[0013] Beneficial effects

[0014] According to the present disclosure, the overall image / video compression efficiency can be improved.

[0015] According to the present disclosure, segmentation efficiency can be improved.

[0016] According to the present disclosure, segmentation efficiency can be improved based on segmentation information of the current picture. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 An example of a video / image encoding system to which embodiments of this document can be applied is schematically illustrated.

[0018] Figure 2 is a schematic diagram illustrating a configuration of a video / image encoding device to which an embodiment of this document can be applied.

[0019] Figure 3 is a schematic diagram illustrating a configuration of a video / image decoding device to which an embodiment of this document can be applied.

[0020] Figure 4An example of a video / image encoding method based on inter-frame prediction is shown.

[0021] Figure 5 FIG. 2 schematically shows an example of an inter-frame predictor in an encoding device.

[0022] Figure 6 An example of a video / image decoding method based on inter-frame prediction is shown.

[0023] Figure 7 An example schematically illustrating an inter-frame predictor in a decoding device is shown.

[0024] Figure 8 An exemplary hierarchy of encoded data is shown.

[0025] Fig. 9 is a diagram showing an example of dividing a picture.

[0026] Fig.10 is a flowchart illustrating a picture encoding process according to an embodiment.

[0027] Fig.11 is a flowchart illustrating a picture decoding process according to an embodiment.

[0028] Fig.12 is a block diagram showing the configuration of an encoding device according to an embodiment.

[0029] Fig.13 is a block diagram showing the configuration of a decoding device according to an embodiment.

[0030] Fig.14 is a flowchart illustrating the operation of an encoding device according to an embodiment.

[0031] Fig.15 is a block diagram showing the configuration of an encoding device according to an embodiment.

[0032] Fig.16 is a flowchart illustrating the operation of a decoding device according to an embodiment.

[0033] Fig.17 is a block diagram showing the configuration of a decoding device according to an embodiment.

[0034] Fig.18 An example of a content streaming system to which the embodiments disclosed in this document can be applied is shown. DETAILED DESCRIPTION

[0035] This document can be modified in various ways and has various embodiments, and specific embodiments will be described in detail and illustrated in the drawings. However, this is not intended to limit this document to specific embodiments. The commonly used terms in this specification are only used to describe specific embodiments, rather than to limit the technical spirit of this document. Singular expressions include plural expressions unless the context clearly indicates otherwise. Terms such as "including" and "having" in this specification should be understood to indicate the presence of characteristics, numbers, steps, operations, elements, parts or combinations thereof described in the specification, and do not exclude the possibility of the presence or addition of one or more other characteristics, numbers, steps, operations, elements, parts or combinations thereof.

[0036] In addition, the elements in the drawings described in this document are independently illustrated for the convenience of describing the different characteristic functions. This does not mean that each element is implemented as different hardware or different software. For example, at least two of the elements can be combined to form a single element, and a single element can also be divided into multiple elements. Without departing from the main purpose of this document, the embodiment in which the elements are combined and / or separated is also included in the scope of the rights of this document.

[0037] In the present disclosure, "A or B" may mean "only A", "only B", or "both A and B". In other words, in the present disclosure, "A or B" may be interpreted as "A and / or B". For example, in the present disclosure, "A, B or C" may mean "only A", "only B", "only C", or "any combination of A, B, C".

[0038] A slash ( / ) or a comma used in the present disclosure may mean "and / or". For example, "A / B" may mean "A and / or B". Thus, "A / B" may mean "only A", "only B", or "both A and B". For example, "A, B, C" may mean "A, B, or C".

[0039] In the present disclosure, "at least one of A and B" may mean "only A", "only B", or "both A and B". In addition, in the present specification, the expression "at least one of A or B" or "at least one of A and / or B" may be interpreted as "at least one of A and B".

[0040] In addition, in the present disclosure, "at least one of A, B, and C" may mean "only A", "only B", "only C", or "any combination of A, B, and C". In addition, "at least one of A, B, or C" or "at least one of A, B and / or C" may mean "at least one of A, B, and C".

[0041] In addition, the brackets used in the present disclosure may mean "for example". Specifically, when indicated as "prediction (intra-frame prediction)", it may mean that "intra-frame prediction" is proposed as an example of "prediction". In other words, the "prediction" of the present disclosure is not limited to "intra-frame prediction", and "intra-frame prediction" may be proposed as an example of "prediction". In addition, when indicated as "prediction (i.e., intra-frame prediction)", it may also mean that "intra-frame prediction" is proposed as an example of "prediction".

[0042] In the present disclosure, technical features separately described in one drawing may be implemented separately or may be implemented simultaneously.

[0043] Hereinafter, preferred embodiments of the present document are described in more detail with reference to the accompanying drawings. Hereinafter, in the accompanying drawings, the same reference numerals are used for the same elements, and redundant descriptions of the same elements may be omitted.

[0044] Figure 1 An example of a video / image encoding system to which embodiments of this document can be applied is schematically illustrated.

[0045] Reference Figure 1 The video / image coding system may include a first device (source device) and a second device (receiving device). The source device may transmit the coded video / image information or data in the form of a file or stream transmission to the receiving device via a digital storage medium or a network.

[0046] The source device may include a video source, an encoding device, and a transmitter. The receiving device may include a receiver, a decoding device, and a renderer. The encoding device may be referred to as a video / image encoding device, and the decoding device may be referred to as a video / image 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, and the display may be configured as a separate device or an external component.

[0047] The video source may acquire the video / image by capturing, synthesizing or generating a video / image process. The video source may include a video / image capturing device, and / or a video / image generating device. For example, the video / image capturing device may include one or more cameras, a video / image archive including previously captured videos / images, etc. For example, the video / image generating device may include a computer, a tablet computer, and a smart phone, and may generate the video / image (electronically). For example, a virtual video / image may be generated by a computer, etc. In this case, the video / image capturing process may be replaced by a process that generates relevant data.

[0048] The encoding device can encode the input video / image. For compression and encoding efficiency, the encoding device can perform a series of processes such as prediction, transformation and quantization. The encoded data (encoded video / image information) can be output in the form of a bit stream.

[0049] The transmitter may transmit the encoded image / image information or data output in the form of a bit stream to a receiver of a receiving device in the form of a file or stream via a digital storage medium or a network. The digital storage medium may include various storage media such as USB, SD, CD, DVD, Blu-ray, HDD, SSD, etc. The transmitter may include an element for generating a media file in a predetermined file format, and may include an element for transmission via a broadcast / communication network. The receiver may receive / extract a bit stream and transmit the received bit stream to a decoding device.

[0050] The decoding device may decode a video / image by performing a series of processes corresponding to the operations of the encoding device, such as inverse quantization, inverse transformation, and prediction.

[0051] The renderer may render the decoded video / image. The rendered video / image may be displayed through a display.

[0052] This document relates to video / image coding. For example, the methods / implementations disclosed in this document can be applied to methods disclosed in the Versatile Video Coding (VVC), EVC (Basic Video Coding) standard, AOMedia Video 1 (AV1) standard, the second generation audio video coding standard (AVS2), or the next generation video / image coding standard (e.g., H.267 or H.268, etc.).

[0053] This document proposes various embodiments of video / image coding, and unless otherwise mentioned, these embodiments may be performed in combination with each other.

[0054] In the present disclosure, a video may mean a collection of a series of images over time. Generally, a picture means a unit of an image representing a specific time region, and a slice / tile is a unit constituting a portion of a picture. A slice / tile may include one or more coding tree units (CTUs). A picture may include one or more slices / tiles.

[0055] A tile is a rectangular area of ​​a CTU within a specific tile column and a specific tile row in a picture. A tile column is a rectangular area of ​​a CTU whose height is equal to the height of the picture and whose width is specified by a syntax element in a picture parameter set. A tile row is a rectangular area of ​​a CTU whose height is specified by a syntax element in a picture parameter set and whose width is equal to the width of the picture. Tile scanning is a specific sequential ordering of CTUs of a partitioned picture as follows: CTUs are continuously ordered by a CTU raster scan in a tile, and tiles in a picture are continuously ordered by a raster scan of tiles of a picture. A slice may include multiple intact tiles or multiple consecutive CTU columns in a tile of a picture that may be included in one NAL unit. In the present disclosure, tile groups may be used interchangeably with slices. For example, in the present disclosure, a tile group / tile group header may be referred to as a slice / slice header.

[0056] In addition, a picture can be divided into two or more sub-pictures. A sub-picture can be a rectangular area of ​​one or more slices within a picture.

[0057] A pixel or a pel may refer to the smallest unit constituting a picture (or image). In addition, a "sample" may be used as a term corresponding to a pixel. A sample may generally represent a pixel or a value of a pixel, and may represent only a pixel / pixel value of a luminance component or a pixel / pixel value of a chrominance component.

[0058] A unit may represent a basic unit of image processing. A unit may include at least one of a specific area of ​​a picture and information related to the area. A unit may include a luminance block and two chrominance (e.g., cb, cr) blocks. In some cases, a unit may be used interchangeably with terms such as a block or an area. In general, an M×N block may include M columns and N rows of samples (or sample arrays) or a set (or array) of transform coefficients.

[0059] Figure 2 is a diagram schematically illustrating a configuration of a video / image encoding device to which an embodiment of the present document can be applied. Hereinafter, the video encoding device may include an image encoding device.

[0060] Reference Figure 2, the encoding device 200 includes an image segmenter 210, a predictor 220, a residual processor 230 and an entropy encoder 240, an adder 250, a filter 260 and a memory 270. The predictor 220 may include an inter-frame predictor 221 and an intra-frame predictor 222. The residual processor 230 may include a transformer 232, a quantizer 233, an inverse quantizer 234 and an inverse transformer 235. The residual processor 230 may also include a subtractor 231. The adder 250 may be referred to as a reconstructor or a reconstructed block generator. According to an embodiment, the image segmenter 210, the predictor 220, the residual processor 230, the entropy encoder 240, the adder 250 and the filter 260 may be configured by at least one hardware component (e.g., an encoder chipset or processor). In addition, the memory 270 may include a decoded picture buffer (DPB), or may be configured by a digital storage medium. The hardware component may also include the memory 270 as an internal / external component.

[0061] The image divider 210 may divide the input image (or picture or frame) input to the encoding device 200 into one or more processors. For example, the processor may be referred to as a coding unit (CU). In this case, the coding unit may be recursively divided from a coding tree unit (CTU) or a maximum coding unit (LCU) according to a quadtree binary tree ternary tree (QTBTTT) structure. For example, one coding unit may be divided into a plurality of coding units with a deeper depth based on a quadtree structure, a binary tree structure, and / or a ternary structure. In this case, for example, a quadtree structure may be applied first, and a binary tree structure and / or a ternary structure may be applied later. Alternatively, a binary tree structure may be applied first. The encoding process according to the present disclosure may be performed based on a final coding unit that is no longer divided. In this case, the maximum coding unit may be used as the final coding unit based on coding efficiency, etc. according to image characteristics, or if necessary, the coding unit may be recursively divided into coding units with a deeper depth and a coding unit with an optimal size may be used as the final coding unit. Here, the encoding process may include a process of prediction, transformation, and reconstruction (to be described later). As another example, the processor may further include a prediction unit (PU) or a transform unit (TU). In this case, the prediction unit and the transform unit may be split or divided from the above-mentioned final coding unit. The prediction unit may be a unit for sample prediction, and the transform unit may be a unit for deriving a transform coefficient and / or a unit for deriving a residual signal from the transform coefficient.

[0062] In some cases, a unit may be used interchangeably with terms such as a block or region. In general, an M×N block may represent a set of samples or transform coefficients consisting of M columns and N rows. A sample may generally represent a pixel or a pixel value, and may represent only a pixel / pixel value of a luma component or only a pixel / pixel value of a chroma component. A sample may be used as a term corresponding to one picture (or image) of a pixel or picture element.

[0063] In the encoding device 200, a prediction signal (prediction block, prediction sample array) output from the inter predictor 221 or the intra predictor 222 is subtracted from the input image signal (original block, original sample array) to generate a residual signal (residual block, residual sample array), and the generated residual signal is sent to the transformer 232. In this case, as shown, the part of the encoding device 200 that subtracts the prediction signal (prediction block, prediction sample array) from the input image signal (original block, original sample array) can be referred to as a subtractor 231. The predictor may perform prediction on a block to be processed (hereinafter, referred to as a current block) and generate a prediction block including prediction samples of the current block. The predictor may determine whether to apply intra prediction or inter prediction based on the current block or CU. As described later in the description of each prediction mode, the predictor may generate various information related to prediction such as prediction mode information, and send the generated information to the entropy encoder 240. Information about the prediction may be encoded in the entropy encoder 240 and output in the form of a bitstream.

[0064] The intra-frame predictor 222 can predict the current block by referring to samples in the current picture. Depending on the prediction mode, the referenced samples may be located near the current block or may be separated. In intra-frame prediction, the prediction mode may include multiple non-directional modes and multiple directional modes. For example, the non-directional mode may include a DC mode and a plane mode. For example, depending on the level of detail of the prediction direction, the directional mode may include 33 directional prediction modes or 65 directional prediction modes. However, this is only an example, and more or fewer directional prediction modes may be used according to the settings. The intra-frame predictor 222 may use the prediction mode applied to the neighboring blocks to determine the prediction mode applied to the current block.

[0065] The inter-frame predictor 221 may derive a prediction block of the current block based on a reference block (reference sample array) specified by a motion vector on a reference picture. Here, in order to reduce the amount of motion information sent in the inter-frame 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 also include inter-frame prediction direction (L0 prediction, L1 prediction, Bi prediction, etc.) information. In the case of inter-frame prediction, the neighboring blocks may include spatial neighboring blocks present in the current picture and temporal neighboring blocks present 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 referred to as a collocated reference block, a collocated CU (colCU), etc., and the reference picture including the temporal neighboring block may be referred to as a collocated picture (colPic). For example, the inter-frame predictor 221 may configure a motion information candidate list based on the neighboring blocks and generate information indicating which candidate is used to derive the motion vector and / or reference picture index of the current block. Inter-frame prediction may be performed based on various prediction modes. For example, in the case of skip mode and merge mode, the inter-frame predictor 221 may use the motion information of the neighboring block as the motion information of the current block. In the skip mode, unlike the merge mode, the residual signal may not be transmitted. In the case of the motion vector prediction (MVP) mode, the motion vector of the neighboring block may be used as a motion vector predictor, and the motion vector of the current block may be indicated by signaling the motion vector difference.

[0066] The predictor 220 can generate a prediction signal based on various prediction methods described below. For example, the predictor can not only apply intra prediction or inter prediction to predict a block, but also apply both intra prediction and inter prediction at the same time. This can be called a combination of inter and intra prediction (CIIP). In addition, the predictor can predict blocks based on an intra-block copy (IBC) prediction mode or a palette mode. The IBC prediction mode or the palette mode can be used for content image / video encoding of games, etc., such as screen content coding (SCC). IBC basically performs prediction in the current picture, but can be performed similarly to inter prediction in terms of deriving a reference block in the current picture. That is, IBC can use at least one of the inter prediction techniques described in this document. The palette mode can be regarded as an example of intra coding or intra prediction. When the palette mode is applied, the sample values ​​within the picture can be signaled based on information about the palette table and the palette index.

[0067] The prediction signal generated by the predictor (including the inter-frame predictor 221 and / or the intra-frame predictor 222) can be used to generate a reconstruction signal or to generate a residual signal. The transformer 232 can generate a transform coefficient 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-loève transform (KLT), a graph-based transform (GBT), or a conditional nonlinear transform (CNT). Here, GBT means a transform obtained from a graph when the relationship information between pixels is represented by a graph. CNT refers to a transform generated based on a prediction signal generated using all previously reconstructed pixels. In addition, the transform process can be applied to square pixel blocks of the same size, or can be applied to blocks of variable size rather than square.

[0068] The quantizer 233 may quantize the transform coefficients and send them to the entropy encoder 240, and the entropy encoder 240 may encode the quantized signal (information about the quantized transform coefficients) and output a bitstream. The information about the quantized transform coefficients may be referred to as residual information. The quantizer 233 may rearrange the quantized transform coefficients of the block type into a one-dimensional vector form based on the coefficient scanning order, and generate information about the quantized transform coefficients based on the quantized transform coefficients in the one-dimensional vector form. Information about the transform coefficients may be generated. The entropy encoder 240 may perform various encoding methods such as (for example) exponential Golomb, context adaptive variable length coding (CAVLC), context adaptive binary arithmetic coding (CABAC), etc. The entropy encoder 240 may encode information necessary for video / image reconstruction other than the quantized transform coefficients (for example, the values ​​of syntax elements, etc.) together or separately. The encoded information (for example, the encoded video / image information) may be transmitted or stored in units of NAL (Network Abstraction Layer) in the form of a bitstream. The video / image information may also include information about various parameter sets such as an adaptive parameter set (APS), a picture parameter set (PPS), a sequence parameter set (SPS), or a video parameter set (VPS). In addition, the video / image information may also include conventional constraint information. In this document, information and / or syntax elements sent / signaled to a decoding device from an encoding device may be included in the video / image information. The video / image information may be encoded and included in a bitstream by the above-mentioned encoding process. The bitstream may be transmitted over a network, or may be stored in a digital storage medium. The network may include a broadcast network and / or a communication network, and the digital storage medium may include various storage media such as USB, SD, CD, DVD, Blu-ray, HDD, SSD, etc. A transmitter (not shown) that sends a signal output from the entropy encoder 240 or a storage (not shown) that stores the signal may be included as an internal / external element of the encoding device 200, and alternatively, the transmitter may be included in the entropy encoder 240.

[0069] The quantized transform coefficients output from the quantizer 233 can be used to generate a prediction signal. For example, the residual signal (residual block or residual sample) can be reconstructed by applying inverse quantization and inverse transformation to the quantized transform coefficients via the inverse quantizer 234 and the inverse transformer 235. The adder 250 adds the reconstructed residual signal to the prediction signal output from the inter-frame predictor 221 or the intra-frame predictor 222 to generate a reconstructed signal (reconstructed picture, reconstructed block, reconstructed sample array). If there is no residual of the block to be processed (such as, when the skip mode is applied), the prediction block can be used as a reconstructed block. The adder 250 can be referred to as a reconstructor or a reconstructed block generator. The generated reconstructed signal can be used for intra-frame prediction of the next block to be processed in the current picture, and as described below, can be used for inter-frame prediction of the next picture through filtering.

[0070] Furthermore, luma mapping with chroma scaling (LMCS) may be applied during the picture encoding and / or reconstruction process.

[0071] The filter 260 can improve the subjective / objective image quality by applying filtering to the reconstructed signal. For example, the filter 260 can generate a modified reconstructed picture by applying various filtering methods to the reconstructed picture, and store the modified reconstructed picture in the memory 270, specifically, in the DPB of the memory 270. Various filtering methods may include, for example, deblocking filtering, sample adaptive offset (SAO), adaptive loop filter, bilateral filter, etc. The filter 260 can generate various types of information related to filtering, and transmit the generated information to the entropy encoder 290, as described in the subsequent description of each filtering method. The information related to filtering can be encoded by the entropy encoder 290 and output in the form of a bit stream.

[0072] The modified reconstructed picture transmitted to the memory 270 may be used as a reference picture in the inter predictor 221. When inter prediction is applied by the encoding device, prediction mismatch between the encoding device 200 and the decoding device may be avoided, and encoding efficiency may be improved.

[0073] The DPB of the memory 270 may store the modified reconstructed picture for use as a reference picture in the inter-frame predictor 221. The memory 270 may store the motion information of the block from which the motion information in the current picture is derived (or encoded) and / or the motion information of the block in the reconstructed picture. The stored motion information may be transmitted to the inter-frame predictor 221 to be used as the motion information of the spatial neighboring block or the motion information of the temporal neighboring block. The memory 270 may store the reconstructed samples of the reconstructed block in the current picture and may transmit the reconstructed samples to the intra-frame predictor 222.

[0074] In addition, in the present disclosure, at least one of quantization / dequantization and / or transform / inverse transform may be omitted. When quantization / dequantization is omitted, the quantized transform coefficient may be referred to as a transform coefficient. When transform / inverse transform is omitted, the transform coefficient may be referred to as a coefficient or a residual coefficient, or may still be referred to as a transform coefficient for consistency of expression.

[0075] In addition, in the present disclosure, the quantized transform coefficient and the transform coefficient may be referred to as a transform coefficient and a scaled transform coefficient, respectively. In this case, the residual information may include information about the transform coefficient, and the information of the transform coefficient may be signaled by a residual coding syntax. The transform coefficient may be derived based on the residual information (or the information of the transform coefficient), and the scaled transform coefficient may be derived by an inverse transform (scaling) of the transform coefficient. The residual sample may be derived based on an inverse transform (transform) of the scaled transform coefficient. This may be applied / expressed in the same manner in other parts of the present disclosure.

[0076] Figure 3 is a diagram schematically illustrating a configuration of a video / image decoding device to which the disclosure of this document can be applied.

[0077] Reference Figure 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-frame predictor 332 and an intra-frame predictor 331. The residual processor 320 may include an inverse quantizer 321 and an inverse transformer 322. According to an embodiment, the entropy decoder 310, the residual processor 320, the predictor 330, the adder 340, and the filter 350 may be configured by a hardware component (e.g., a decoder chipset or a processor). In addition, the memory 360 may include a decoded picture buffer (DPB) or may be configured by a digital storage medium. The hardware component may also include a memory 360 as an internal / external component.

[0078] When a bit stream including video / image information is input, the decoding device 300 can reconstruct the bit stream corresponding to the bit stream in the video / image format. Figure 2 The image corresponding to the processing of the video / image information in the encoding device. For example, the decoding device 300 may derive the unit / block based on the block segmentation related information obtained from the bit stream. The decoding device 300 may use a processor applied in the encoding device to perform decoding. Therefore, for example, the decoding processor may be a coding unit, and the coding unit may be divided from a coding tree unit or a maximum coding unit according to a quadtree structure, a binary tree structure and / or a ternary tree structure. One or more transform units may be derived from the coding unit. The reconstructed image signal decoded and output by the decoding device 300 may be reproduced by a reproduction device.

[0079] The decoding device 300 may receive the Figure 2 The received signal can be decoded by the entropy decoder 310. For example, the entropy decoder 310 can parse the bitstream to derive information (e.g., video / image information) necessary for image reconstruction (or picture reconstruction). The video / image information may also include information about various parameter sets such as an adaptive parameter set (APS), a picture parameter set (PPS), a sequence parameter set (SPS), or a video parameter set (VPS). In addition, the video / image information may also include conventional constraint information. The decoding device may also decode the picture based on information about the parameter set and / or conventional constraint information. The signaled / received information and / or syntax elements subsequently described in this document may be decoded by a decoding process and obtained from the bitstream. For example, the entropy decoder 310 may decode the information in the bitstream based on a coding method such as exponential Golomb coding, CABAC, or CAVLC, and output syntax elements required for image reconstruction and quantized values ​​of transform coefficients for the residual. More specifically, the CABAC entropy decoding method can receive the bin corresponding to each syntax element in the bitstream, use the decoding target syntax element information, the decoding information of the decoding target block, or the information of the symbol / bin decoded in the previous stage to determine the context model, and perform arithmetic decoding on the bin by predicting the probability of occurrence of the bin according to the determined context model, and generate a symbol corresponding to the value of each syntax element. In this case, the CABAC entropy decoding method can update the context model by using the information of the decoded symbol / bin for the context model of the next symbol / bin after determining the context model. The information related to prediction among the information decoded by the entropy decoder 310 can be provided to the predictor (inter-frame predictor 332 and intra-frame predictor 331), and the residual value (ie, the quantized transform coefficient and related parameter information) entropy decoded in the entropy decoder 310 can be input to the residual processor 320. The residual processor 320 can derive a residual signal (residual block, residual sample, residual sample array). In addition, the information about filtering among the information decoded by the entropy decoder 310 can be provided to the filter 350. In addition, a receiver (not shown) for receiving a signal output from the encoding device may be additionally configured as an internal / external element of the decoding device 300, or the receiver may be a component of the entropy decoder 310. In addition, the decoding device according to the present document may be referred to as a video / image / picture decoding device, and the decoding device may be classified 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 decoder 310, and the sample decoder may include at least one of the inverse quantizer 321, the inverse transformer 322, the adder 340, the filter 350, the memory 360, the inter-frame predictor 332, and the intra-frame predictor 331.

[0080] The dequantizer 321 may dequantize the quantized transform coefficient and output the transform coefficient. The dequantizer 321 may rearrange the quantized transform coefficient in a two-dimensional block form. In this case, the rearrangement may be performed based on the coefficient scanning order performed in the encoding device. The dequantizer 321 may perform dequantization on the quantized transform coefficient using a quantization parameter (e.g., quantization step size information) and obtain the transform coefficient.

[0081] The inverse transformer 322 inversely transforms the transform coefficients to obtain a residual signal (residual block, residual sample array).

[0082] The predictor may perform prediction on the current block and generate a prediction block including prediction samples of the current block. The predictor may determine whether to apply intra prediction or inter prediction to the current block based on information on prediction output from the entropy decoder 310 and may determine a specific intra / inter prediction mode.

[0083] The predictor can generate a prediction signal based on various prediction methods described below. For example, the predictor can not only apply intra prediction or inter prediction to predict a block, but also apply intra prediction and inter prediction at the same time. This can be called inter and intra prediction combination (CIIP). In addition, the predictor can predict blocks based on intra-block copy (IBC) prediction mode or palette mode. IBC prediction mode or palette mode can be used for content image / video encoding of games, etc., for example, screen content coding (SCC). IBC basically performs prediction in the current picture, but can be performed similarly to inter prediction in terms of deriving reference blocks in the current picture. That is, IBC can use at least one of the inter prediction techniques described in this document. The palette mode can be regarded as an example of intra coding or intra prediction. When the palette mode is applied, the sample values ​​within the picture can be signaled based on information about the palette table and the palette index.

[0084] The intra-frame predictor 331 can predict the current block by referring to samples in the current picture. Depending on the prediction mode, the referenced samples can be located near the current block, or can be located separately. In intra-frame prediction, the prediction mode can include multiple non-directional modes and multiple directional modes. The intra-frame predictor 331 can determine the prediction mode applied to the current block by using the prediction mode applied to the neighboring blocks.

[0085] The inter-frame predictor 332 may derive a prediction block of the current block based on a reference block (reference sample array) specified by a motion vector on a reference picture. In this case, in order to reduce the amount of motion information sent in the inter-frame prediction mode, the motion information may be predicted in units of blocks, sub-blocks, or samples based on the correlation of the motion information between the neighboring blocks and the current block. The motion information may include a motion vector and a reference picture index. The motion information may also include inter-frame prediction direction (L0 prediction, L1 prediction, Bi prediction, etc.) information. In the case of inter-frame prediction, the neighboring blocks may include spatial neighboring blocks present in the current picture and temporal neighboring blocks present in the reference picture. For example, the inter-frame predictor 332 may configure a motion information candidate list based on neighboring blocks, and derive a motion vector and / or reference picture index of the current block based on the received candidate selection information. Inter-frame prediction may be performed based on various prediction modes, and information about the prediction may include information indicating a mode of inter-frame prediction for the current block.

[0086] The adder 340 may generate a reconstructed signal (reconstructed picture, reconstructed block, or reconstructed sample array) by adding the obtained residual signal to the prediction signal (prediction block or prediction sample array) output from the predictor 330. If there is no residual of the processing target block (such as the case where the skip mode is applied), the prediction block may be used as the reconstructed block.

[0087] The adder 340 may be referred to as a reconstructor 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, and as described later, may also be output through filtering or may also be used for inter prediction of the next picture.

[0088] In addition, luminance mapping with chroma scaling (LMCS) can also be applied to the picture decoding process.

[0089] The filter 350 can improve the subjective / objective image quality by applying filtering to the reconstructed signal. For example, the filter 350 can generate a modified reconstructed picture by applying various filtering methods to the reconstructed picture, and store the modified reconstructed picture in the memory 360, specifically, in the DPB of the memory 360. The various filtering methods may include, for example, deblocking filtering, sample adaptive offset, adaptive loop filter, bilateral filter, etc.

[0090] The (modified) reconstructed picture stored in the DPB of the memory 360 may be used as a reference picture in the inter-frame predictor 332. The memory 360 may store the motion information of the block from which the motion information in the current picture is derived (or decoded) and / or the motion information of the block in the reconstructed picture. The stored motion information may be transmitted to the inter-frame predictor 332 so as to be used as the motion information of the spatial neighboring block or the motion information of the temporal neighboring block. The memory 360 may store the reconstructed samples of the reconstructed block in the current picture and transmit the reconstructed samples to the intra-frame predictor 331.

[0091] In the present disclosure, the embodiments described in the filter 260, the inter-frame predictor 221, and the intra-frame predictor 222 of the encoding device 200 may be the same as the filter 350, the inter-frame predictor 332, and the intra-frame predictor 331 of the decoding device 300 or may be respectively applied to correspond to the filter 350, the inter-frame predictor 332, and the intra-frame predictor 331 of the decoding device 300. This may also be applicable to the inter-frame predictor 332 and the intra-frame predictor 331.

[0092] As described above, when performing video encoding, prediction is performed to enhance compression efficiency. A prediction block including prediction samples of a current block (ie, a target coding block) may be generated by prediction. In this case, the prediction block includes prediction samples in a spatial domain (or a pixel domain). The prediction block is derived identically in the encoding device and the decoding device. The encoding device may enhance image coding efficiency by signaling information (residual information) about the residual between the original block (rather than the original sample value of the original block itself) and the prediction block to the decoding device. The decoding device may derive a residual block including residual samples based on the residual information, may generate a reconstructed block including reconstructed samples by adding the residual block and the prediction block, and may generate a reconstructed picture including the reconstructed block.

[0093] The residual information may be generated through a transformation process and a quantization process. For example, the encoding device may derive a residual block between the original block and the prediction block, may derive a transform coefficient by performing a transformation process on the residual samples (residual sample array) included in the residual block, may derive a quantized transform coefficient by performing a quantization process on the transform coefficient, and may signal the relevant residual information (through a bitstream) to the decoding device. In this case, the residual information may include value information of the quantized transform coefficient, position information, transform scheme, transform kernel, and quantization parameter, etc. The decoding device may perform an inverse quantization / inverse transform process based on the residual information and may derive a residual sample (or residual block). The decoding device may generate a reconstructed picture based on the prediction block and the residual block. In addition, for the inter-frame prediction reference of subsequent pictures, the encoding device may derive a residual block by inverse quantizing / inverse transforming the quantized transform coefficient, and may generate a reconstructed picture.

[0094] Figure 4 An example of a video / image encoding method based on inter-frame prediction is shown, and Figure 5 FIG. 2 schematically shows an example of an inter-frame predictor in an encoding device. Figure 5 The inter-frame predictor in the encoding device can also be applied as Figure 2 The same as or corresponding to the inter-frame predictor 221 of the encoding device 200.

[0095] Reference Figure 4 and Figure 5 , the encoding device performs inter prediction on the current block (S400). The encoding device may derive the inter prediction mode and motion information of the current block and generate a prediction sample of the current block. Here, the inter prediction mode determination process, the motion information derivation process, and the prediction sample generation process may be performed simultaneously, and any one process may be performed earlier than the other processes.

[0096] For example, the inter-frame predictor 221 of the encoding device may include a prediction mode determiner 221_1, a motion information deriver 221_2, and a prediction sample deriver 221_3, and the prediction mode determiner 221_1 may determine the prediction mode of the current block, the motion information deriver 221_2 may derive the motion information of the current block, and the prediction sample deriver 221_3 may derive the prediction sample of the current block. For example, the inter-frame predictor 221 of the encoding device may search for a block similar to the current block in a predetermined area (search area) of a reference picture through motion estimation, and derive a reference block in which the difference with the current block is the smallest or equal to or less than a predetermined standard. Based on this, a reference picture index indicating the reference picture where the reference block is located may be derived, and a motion vector may be derived based on the position difference between the reference block and the current block. The encoding device may determine a mode applied to the current block among various prediction modes. The encoding device may compare the RD costs of various prediction modes and determine the best prediction mode for the current block.

[0097] For example, when the skip mode or merge mode is applied to the current block, the encoding device may configure a merge candidate list to be described below, and derive a reference block indicated by a merge candidate included in the merge candidate list, which has the smallest difference from the current block or is equal to or less than a predetermined standard. In this case, a merge candidate associated with the derived reference block may be selected, and merge index information indicating the selected merge candidate may be generated and signaled to the decoding device. The motion information of the current block may be derived by using the motion information of the selected merge candidate.

[0098] As another example, when the (A)MVP mode is applied to the current block, the encoding device may configure the (A)MVP candidate list and use the motion vector of the selected MVP candidate among the motion vector predictor (MVP) candidates included in the (A)MVP candidate list as the MVP of the current block. In this case, for example, the motion vector indicating the reference block derived by motion estimation may be used as the motion vector of the current block, and the MVP candidate having the motion vector with the smallest difference from the motion vector of the current block among the MVP candidates may become the selected MVP candidate. A motion vector difference (MVD) may be derived, which is the difference obtained by subtracting the MVP from the motion vector of the current block. In this case, information about the MVD may be signaled to the decoding device. In addition, when the (A)MVP mode is applied, the value of the reference picture index may be configured as reference picture index information and signaled separately to the decoding device.

[0099] The encoding apparatus may induce residual samples based on the prediction samples (S410). The encoding apparatus may induce residual samples by comparing original samples and prediction samples of the current block.

[0100] The encoding device encodes the image information including prediction information and residual information (S420). The encoding device can output the encoded image information in the form of a bitstream. The prediction information may include information about prediction mode information (e.g., a skip flag, a merge flag, or a mode index, etc.) and information about motion information as information related to the prediction process. The information about the motion information may include candidate selection information (e.g., a merge index) as information for deriving a motion vector. In addition, the information about the motion information may include information indicating whether L0 prediction, L1 prediction, or bidirectional prediction is applied. The residual information is information about residual samples. The residual information may include information about quantized transform coefficients of the residual samples.

[0101] The output bitstream may be stored in a (digital) storage medium and transmitted to a decoding device or transmitted to a decoding device via a network.

[0102] In addition, as described above, the encoding device may generate a reconstructed picture (including a reconstructed sample and a reconstructed block) based on the reference sample and the residual sample. This is to derive the same prediction result as the prediction result performed by the decoding device, and as a result, the encoding efficiency can be improved. Therefore, the encoding device may store the reconstructed picture (or the reconstructed sample or the reconstructed block) in a memory and use the reconstructed picture as a reference picture. The loop filtering process can be further applied to the reconstructed picture as described above.

[0103] Figure 6 An example of a video / image decoding method based on inter-frame prediction is shown, and Figure 7 FIG. 1 schematically shows an example of an inter-frame predictor in a decoding device. Figure 7 The inter-frame predictor in the decoding device can also be applied as Figure 3 The same as or corresponds to the inter-frame predictor 332 of the decoding device 300.

[0104] Reference Figure 6 and Figure 7 The decoding device may perform an operation corresponding to the operation performed by the encoding device. The decoding device may perform prediction on the current block based on the received prediction information and derive a prediction sample.

[0105] Specifically, the decoding apparatus may determine a prediction mode of the current block based on the received prediction information (S600). The decoding apparatus may determine which inter prediction mode to apply to the current block based on prediction mode information in the prediction information.

[0106] The inter prediction mode candidates may include a skip mode, a merge mode, and / or an (A)MVP mode or may include various inter prediction modes.

[0107] The decoding device derives motion information of the current block based on the determined inter-frame prediction mode (S610). For example, when the skip mode or the merge mode is applied to the current block, the decoding device may configure a merge candidate list and select a merge candidate from the merge candidates included in the merge candidate list. Here, the selection may be performed based on the selection information (merge index). The motion information of the current block may be derived using the motion information of the selected merge candidate. The motion information of the selected merge candidate may be used as the motion information of the current block.

[0108] As another example, when the (A)MVP mode is applied to the current block, the decoding device may configure the (A)MVP candidate list and use the motion vector of the selected MVP candidate among the motion vector predictor (MVP) candidates included in the (A)MVP candidate list as the MVP of the current block. Here, the selection may be performed based on the selection information (MVP flag or MVP index). In this case, the MVD of the current block may be derived based on the information about the MVD, and the motion vector of the current block may be derived based on the MVP and MVD of the current block. In addition, the reference picture index of the current block may be derived based on the reference picture index information. The picture indicated by the reference picture index in the reference picture list of the current block may be derived as the reference picture of the inter-frame prediction reference of the current block.

[0109] In addition, the motion information of the current block may be derived without the candidate list configuration, and in this case, the motion information of the current block may be derived according to the process disclosed in the prediction mode. In this case, the candidate list configuration may be omitted.

[0110] The decoding device may generate a prediction sample of the current block based on the motion information of the current block (S620). In this case, the reference picture may be derived based on the reference picture index of the current block, and the prediction sample of the current block may be derived by using a sample of the reference block indicated by the motion vector of the current block on the reference picture. In this case, in some cases, a prediction sample filtering process for all or some prediction samples of the current block may be further performed.

[0111] For example, the inter-frame predictor 332 of the decoding device may include a prediction mode determiner 332_1, a motion information deriver 332_2 and a prediction sample deriver 332_3, and the prediction mode determiner 332_1 may determine the prediction mode of the current block based on the received prediction mode information, the motion information deriver 332_2 may derive the motion information (motion vector and / or reference picture index) of the current block based on the information about the received motion information, and the prediction sample deriver 332_3 may derive the prediction sample of the current block.

[0112] The decoding device generates a residual sample of the current block based on the received residual information (S630). The decoding device may generate a reconstructed sample of the current block based on the predicted sample and the residual sample, and generate a reconstructed picture based on the generated reconstructed sample (S640). Thereafter, the loop filtering process may be further applied to the reconstructed picture as described above.

[0113] As described above, the inter-frame prediction process may include an inter-frame prediction mode determination step, a motion information derivation step depending on the determined prediction mode, and a prediction execution (prediction sample generation) step based on the derived motion information. The inter-frame prediction process may be performed by the encoding device and the decoding device as described above.

[0114] In addition, when deriving the motion information of the current block, motion information candidates can be derived based on spatial neighboring blocks and temporal neighboring blocks, and the motion information candidate of the current block can be selected based on the derived motion information candidate. At this time, the selected motion information candidate can be used as the motion information of the current block.

[0115] Figure 8 An exemplary hierarchy of encoded data is shown.

[0116] Reference Figure 8 , the encoded data can be divided into a video coding layer (VCL) that manipulates the encoding process of the video / image and the video / image itself, and a network abstraction layer (NAL) that stores and transmits the encoded video / image data and is located between the video coding layer (VCL) and lower systems.

[0117] The VCL may generate a Supplemental Enhancement Information (SEI) message that is supplemented in the encoding process corresponding to the header of the sequence and the picture and the parameter set of the video / image (Picture Parameter Set (PPS), Sequence Parameter Set (SPS), Video Parameter Set (VPS), etc.). The SEI message is separated from the information (slice data) for the video / image. The VCL including the information for the video / image includes slice data and a slice header. In addition, the slice header may be referred to as a tile group header, and the slice data may be referred to as a tile group data.

[0118] In NAL, a NAL unit can be generated by adding header information (NAL unit header) to a raw byte sequence payload (RBSP) generated in a VCL. In this case, RBSP is referred to as slice data, parameter sets, SEI messages, etc. generated in a VCL. The NAL unit header may include NAL unit type information specified according to the RBSP data included in the NAL unit.

[0119] The NAL unit, which is a basic unit of NAL, performs a function of mapping a coded image to a bit sequence of a lower system such as a file format, a real-time transport protocol (RTP), a transport stream (TS), etc. according to a predetermined specification.

[0120] As shown in the figure, according to the RBSP generated in the VCL, the NAL unit can be divided into a VCL NAL unit and a non-VCL NAL unit. The VCL NAL unit may mean a NAL unit including information (slice data) for an image, and the non-VCL NAL unit may mean a NAL unit including information required for decoding an image (parameter set or SEI message).

[0121] The above-mentioned VCL NAL unit and non-VCL NAL unit can be sent through the network by attaching header information according to the data specification of the lower system. For example, the NAL unit can be converted into a predetermined standardized data format such as H.266 / VVC file format, RTP (Real-time Transport Protocol), TS (Transport Stream), etc.

[0122] As described above, for a NAL unit, a NAL unit type may be specified according to an RBSP data structure included in the NAL unit, and information of the NAL unit type may be stored in a NAL unit header and signaled.

[0123] For example, NAL units can be classified into VCL NAL unit types and non-VCL NAL unit types according to whether the NAL unit includes information (slice data) for an image. VCL NAL unit types can be classified according to the nature and type of the picture included in the VCL NAL unit, and non-VCL NAL unit types can be classified according to the type of parameter set.

[0124] An example of a NAL unit type specified according to the type of parameter set included in a non-VCL NAL unit type is described below. The NAL unit type may be specified according to the type of parameter set. For example, the NAL unit type may be specified as one of an APS (adaptive parameter set) NAL unit (including the type of NAL unit of the APS), a DPS (decoding parameter set) NAL unit (including the type of NAL unit of the DPS), a VPS (video parameter set) NAL unit (including the type of NAL unit of the VPS), an SPS (sequence parameter set) NAL unit (including the type of NAL unit of the SPS), and a PPS (picture parameter set) NAL unit (including the type of NAL unit of the PPS).

[0125] The above-mentioned NAL unit type may have syntax information for the NAL unit type, and the syntax information may be stored in the NAL unit header and signaled. For example, the syntax information may be nal_unit_type, and the NAL unit type may be specified as a nal_unit_type value.

[0126] In addition, as described above, a picture may have multiple slices, and a slice may include a slice header and slice data. In this case, in addition to multiple slices (a set of slice headers and slice data), a picture header may be added to a picture. The picture header (picture header syntax) may include information / parameters that may be commonly applied to the picture. The slice header (slice header syntax) may include information / parameters that may be commonly applied to the slice. APS (APS syntax) or PPS (PPS syntax) may include information / parameters that may be commonly applied to one or more slices or pictures. SPS (SPS syntax) may include information / parameters that may be commonly applied to one or more sequences. VPS (VPS syntax) may include information / parameters that may be commonly applied to multiple layers. DPS (DPS syntax) may include information / parameters that may be commonly applied to the entire video. DPS may include information / parameters related to the concatenation of CVS (coded video sequence). In the present disclosure, the high-level syntax (HLS) may include at least one of APS syntax, PPS syntax, SPS syntax, VPS syntax, DPS syntax, picture header syntax, or slice header syntax.

[0127] In the present disclosure, the image / video information encoded from the encoding device to the decoding device and signaled in a bitstream format may include information included in a slice header, information included in a picture header, information included in an APS, information included in a PPS, information included in an SPS, information included in a VPS, and / or information included in a DPS, as well as information related to segmentation in a picture, intra / inter prediction information, residual information, loop filtering information, etc. In addition, the image / video information may also include information in a NAL unit header.

[0128] Fig. 9 is a diagram showing an example of dividing a picture.

[0129] A picture may be partitioned into coding tree units (CTUs), and a CTU may correspond to a coding tree block (CTB). A CTU may include a coding tree block of luma samples and corresponding two coding tree blocks of chroma samples. In addition, the maximum available size of a CTU for encoding and prediction may be different from the maximum available size of a CTU for transform.

[0130] A tile may correspond to a series of CTUs covering a rectangular area, and one picture may be partitioned into one or more tile rows and one or more tile columns.

[0131] In addition, a slice may include an integer number of intact tiles or an integer number of consecutive intact CTU columns. In this case, two types of slice modes may be supported, including a raster scan slice mode and a rectangular slice mode.

[0132] In raster scan slicing mode, a slice may include a series of intact tiles in a tile raster scan of a picture. In rectangular slicing mode, a slice may include multiple intact tiles that together form a rectangular area of ​​a picture. Alternatively, in rectangular slicing mode, a slice may include multiple consecutive CTU columns in tiles that together form a rectangular area of ​​a picture. Tiles in a rectangular slice may be scanned in a tile raster scan order in a rectangular area corresponding to the corresponding slice.

[0133] Furthermore, a sub-picture may include one or more slices covering a rectangular area of ​​a picture.

[0134] Fig. 9 (a) is a diagram showing an example of dividing a picture into raster scan slices. For example, the picture can be divided into 12 tiles and 3 raster scan slices.

[0135] also, Fig. 9 (b) is a diagram showing an example of dividing a picture into rectangular slices. For example, the picture can be divided into 24 tiles (6 tile rows and 4 tile columns) and 9 rectangular slices.

[0136] also, Fig. 9 (c) is a diagram showing an example of dividing a picture into tiles and rectangular slices. For example, a picture can be divided into 24 tiles (2 tile rows and 2 tile columns) and 4 rectangular slices.

[0137] Fig.10 is a flowchart illustrating a picture encoding process according to an embodiment.

[0138] In one embodiment, picture segmentation may be performed by the image segmentor 210 of the encoding device (step S1000 ), and picture encoding may be performed by the entropy encoder 240 of the encoding device (step S1010 ).

[0139] The encoding device according to the embodiment may derive the slices and / or tiles included in the current picture (step S1000). For example, the encoding device may perform picture segmentation to encode the input current picture. For example, the encoding device may derive the slices and / or tiles included in the current picture. The encoding device may segment the picture in various formats by considering the image properties and encoding efficiency of the current picture, and generate information indicating the segmentation format with the best encoding efficiency, and then signal the information to the decoding device.

[0140] The encoding device according to the embodiment may perform encoding on the current picture based on the derived slice and / or tile (step S1010). For example, the encoding device may encode the video / image information including the information of the slice and / or tile, and output the information in a bitstream format. The output bitstream may be forwarded to the decoding device via a digital storage medium or a network.

[0141] Fig.11 is a flowchart illustrating a picture decoding process according to an embodiment.

[0142] In one embodiment, the step of obtaining video / image information from a bitstream (step S710) and the step of deriving slices and / or tiles in the current picture (step S720) may be performed by the entropy decoder 310 of the decoding device, and the step of reconstructing the current picture based on the slices and / or tiles may be performed by the adder 340 of the decoding device.

[0143] The decoding device according to the embodiment may obtain video / image information from the received bit stream (step S1110). The video / image information may include HLS, and the HLS may include slice information or tile information. The slice information may include information for specifying one or more slices in the current picture, and the tile information may include information for specifying one or more tiles in the current picture. The slice information or tile information may be obtained through various parameter sets, picture headers, and / or slice headers.

[0144] Furthermore, the current picture may include a tile including one or more slices or a slice including one or more tiles.

[0145] The decoding device according to an embodiment may derive a slice and / or a tile in the current picture based on video / image information including information of the slice and / or the tile (step S1120).

[0146] The decoding apparatus according to the embodiment may reconstruct (decode) the current picture based on slices and / or tiles (step S1130 ).

[0147] Fig.12 is a block diagram showing a configuration of an encoding device according to an embodiment, and Fig.13 is a block diagram showing the configuration of a decoding device according to an embodiment.

[0148] Fig.12 An example of a block diagram of an encoding device is shown. Fig.12 The encoding device 1200 shown includes a segmenter 1210 and an entropy encoder 1220. The segmenter 1210 may perform the same Figure 2 The image segmentation device 210 of the encoding device shown in FIG. 1 may perform the same and / or similar operations as the image segmentation device 210 of the encoding device shown in FIG. 1 , and the entropy encoder 1220 may perform the same and / or similar operations as the image segmentation device 210 of the encoding device shown in FIG. 1 . Figure 2 The encoding device 1200 may perform the same and / or similar operations as the entropy encoder 240 of the encoding device shown in the figure. For example, the segmenter 1210 may derive at least one slice and / or at least one tile included in the current picture. For example, the encoding device may perform picture segmentation for encoding of the input current picture. The input video may be segmented in the segmenter 1210 and may be encoded in the entropy encoder 1220. After encoding, the encoded video may be output from the encoding device 1200.

[0149] Fig.13 An example of a block diagram of a decoding device is shown. Fig.13 The decoding device 1300 shown includes an entropy decoder 1310 and a reconstruction processor 1320. The entropy decoder 1310 can perform the same Figure 3 The reconstruction processor 1320 may include, in addition to the above-mentioned Figure 3 At least one component other than the entropy decoder 310 shown. The entropy decoder 1310 may decode the input received from the encoding device 800 and derive information of the tile. The processing unit may be determined based on the decoded information, and the reconstruction processor 13 may perform decoding based on the processing unit and may generate a reconstructed sample.

[0150] In addition, as described above, a picture can be divided into sub-pictures, tiles, and slices. The information of sub-pictures can be signaled by SPS, and the information of tiles and rectangular slices can be signaled by PPS. In addition, the information of raster scan slices can be signaled by slice heads.

[0151] For example, the SPS syntax including sub-picture information may be represented as shown in the following table.

[0152] [Table 1]

[0153]

[0154] For example, the PPS syntax including information of tiles and rectangular slices may be represented as shown in the following table.

[0155] [Table 2]

[0156]

[0157] In addition, for example, the syntax of the slice header including information of the raster scan slice can be expressed as in the following table.

[0158] [Table 3]

[0159]

[0160] In addition, the information of the slices in the current picture and the information of the tiles may include a flag related to whether each sub-picture in the current picture includes a single slice. The flag may be referred to as single_slice_per_subpic_flag or pps_single_slice_per_subpic_flag, but may not be limited thereto. In addition, the information of the sub-picture may include a flag related to the presence of sub-picture information, and the flag may be referred to as subpics_present_flag or sps_subpic_info_present_flag, but may not be limited thereto. For example, the information of the sub-picture may be included in a parameter set. For example, the information of the sub-picture may be included in an SPS.

[0161] Conventionally, in the case where the value of the flag related to the presence of sub-picture information is zero, the value of the flag is limited so that the value of the flag related to whether the sub-picture includes only one slice becomes zero. That is, in the case where the value of the flag related to the presence of sub-picture information is zero, the sub-picture is determined to be unavailable, and the value of the flag related to whether the sub-picture includes only one slice is limited to zero. However, this condition is very strict. For example, even in the absence of sub-picture information, the current picture can be divided into two or more tiles, and all tiles can be included in a single slice. In this case, the current picture includes only one slice.

[0162] Therefore, an embodiment of the present disclosure proposes a method for eliminating the restriction that the value of a flag related to whether a sub-picture includes only one slice becomes zero when the value of a flag related to the presence of sub-picture information is zero. In this case, the flag related to whether a sub-picture includes only one slice can indicate a case where the current picture includes only one slice even when there is no sub-picture information.

[0163] For example, according to an embodiment, even if there is no sub-picture information in the coding layer video sequence (CLVS), there may be a flag related to whether the sub-picture includes only one slice. That is, even if there is no sub-picture information in the CLVS, the flag related to whether the sub-picture includes only one slice may have a value of zero or 1.

[0164] For example, in the case where the value of the flag related to the presence of sub-picture information is zero and the value of the flag related to whether the sub-picture includes only one slice is 1, the current picture may include only one slice. That is, in the case where there is no signaled sub-picture and the value of the flag related to whether the sub-picture includes only one slice is 1, the number of slices in the picture may be inferred to be 1.

[0165] In addition, when the value of the flag related to the existence of sub-picture information is zero, the number of sub-pictures in the current picture may be 1. For example, when the value of the flag related to the existence of sub-picture information is zero, the number of sub-pictures present in each of all pictures of the SPS of the reference image information may be 1.

[0166] In addition, a flag related to the number of slices included in the current picture may be included in the PPS of the image information. The flag related to the number of slices included in the current picture may be referred to as num_slices_in_pic_minus1 or pps_num_slices_in_pic_minus1, but may not be limited thereto. In addition, a flag related to the number of sub-pictures included in the current picture may be included in the SPS of the image information. The flag related to the number of sub-pictures included in the current picture may be referred to as sps_num_subpics_minus1, but may not be limited thereto.

[0167] In the case where there is no sub-picture information and the value of the flag related to whether the sub-picture includes only one slice is 1, the flag related to the number of slices included in the current picture may be inferred to have a value of 0. In addition, in the case where there is no sub-picture information and the value of the flag related to whether the sub-picture includes only one slice is 1, the flag related to the number of slices included in the current picture and the flag related to the number of sub-pictures included in the current picture may be inferred to have the same value.

[0168] In addition, in the case where the value of the flag related to whether the sub-picture includes only one slice is 1, all CTUs in the picture may belong to only one slice included in the picture.

[0169] The semantics of the syntax element including a flag related to whether a sub-picture includes only one slice and a flag related to the number of slices included in the current picture can be represented as in the following table.

[0170] [Table 4]

[0171]

[0172] Referring to the above table, in the case where the value of single_slice_per_subpic_flag corresponding to the flag related to whether the sub-picture includes only one slice is 1, each sub-picture may include a single rectangular slice. In addition, in the case where the value of single_slice_per_subpic_flag is zero, each sub-picture may include one or more rectangular slices. In the case where the value of single_slice_per_subpic_flag is 1, the value of num_slices_in_pic_minus1 corresponding to the flag related to the number of slices included in the current picture may be inferred to have a value of sps_num_subpics_minus1 corresponding to the flag related to the number of sub-pictures included in the current picture.

[0173] Also, in the case where a value of single_slice_per_subpic_flag is 1 and a value of subpics_present_flag corresponding to a flag related to the presence of sub-picture information is zero, a picture referring to the PPS may have a single slice per picture.

[0174] In addition, the scanning process, which is the order in which tiles in a picture are decoded, can be determined according to the following table.

[0175] [Table 5]

[0176]

[0177]

[0178] Fig.14 is a flowchart showing the operation of an encoding device according to an embodiment, and Fig.15 is a block diagram showing the configuration of an encoding device according to an embodiment.

[0179] Fig.14 The method shown can be Figure 2 or Fig.15 The encoding device shown performs. Fig.14 Steps S1410 and S1420 shown in FIG. 14 can be performed by Figure 2 The image segmenter 210 shown in FIG. 1 is executed, and steps S1430 and S1440 may be performed by Figure 2 The residual processor 230 shown in FIG. 1 is executed. In addition, Fig.14 Step S1450 shown can be performed by Figure 2 The entropy encoder 240 shown performs. In addition, although Fig.14 Not shown, but the prediction samples or prediction related information can be obtained by Fig.15 In addition, the operations according to steps S1410 to S1450 are based on the reference Figures 1 to 13 Therefore, the description and reference are omitted or briefly described. Figures 1 to 13 The description of the specification overlaps the detailed description.

[0180] Reference Fig.14 According to an embodiment, the encoding device may divide the current picture into at least one slice (step S1410). For example, the encoding device may divide the current picture into at least one sub-picture, at least one slice and / or at least one tile. For example, the encoding device may perform picture segmentation to encode the input current picture.

[0181] According to an embodiment, the encoding device may generate segmentation information of the current picture based on at least one slice (step S1420). For example, the image segmentor 210 of the encoding device may generate segmentation information of the current picture based on at least one sub-picture, at least one slice and / or at least one tile.

[0182] The encoding device according to the embodiment may derive the residual sample of the current block included in the at least one slice (step S1430). For example, the residual processor 230 of the encoding device may derive the residual sample of the current block included in one slice of the at least one slice. For example, the encoding device may derive the residual sample based on the predicted sample and the original sample. For example, the encoding device may generate residual information representing the quantized transform coefficient of the residual sample. Various encoding methods such as exponential Golomb, CAVLC, CABAC, etc. may be used to generate the residual information.

[0183] The encoding apparatus according to an embodiment may generate residual information of the current block based on the residual sample (step S1440 ).

[0184] The encoding device according to the embodiment may encode the image information including the segmentation information and the residual information (step S1450). For example, the image information may include at least one of the segmentation information of the current picture or the residual information of the current block. Alternatively, the image information may include prediction information generated from the prediction sample in the predictor 220 of the encoding device. The prediction information may include information for the inter-frame prediction mode or the intra-frame prediction mode performed in the current picture.

[0185] For example, the image information may include a first flag related to the presence of sub-picture information and a second flag related to whether the sub-picture includes only one slice. For example, based on the first flag and the second flag, the number of slices included in the current picture may be derived to be equal to 1.

[0186] For example, in a case where a value of a first flag related to the presence of sub-picture information is 0 and a value of a second flag is 1, the number of slices included in the current picture may be derived to be equal to 1.

[0187] For example, the first flag related to the presence of the sub-picture information may be included in the SPS (Sequence Parameter Set) of the image information.

[0188] For example, the second flag related to whether the sub-picture includes only one slice may be included in the PPS (Picture Parameter Set) of the image information.

[0189] For example, the image information may include a third flag related to the number of slices included in the current picture, and the third flag may be included in the PPS of the image information.

[0190] In addition, for example, the image information may include a fourth flag related to the number of sub-pictures included in the current picture, and the fourth flag may be included in the SPS of the image information.

[0191] In addition, for example, in the case where the value of the first flag is zero, the number of sub-pictures present in each of all pictures of the SPS of the reference image information can be derived to be equal to 1.

[0192] In addition, the image information may include prediction information of the current picture. The prediction information may include information of an inter-frame prediction mode or an intra-frame prediction mode performed in the current picture. The encoding device may generate the prediction information of the current picture and encode it.

[0193] In addition, the bitstream can be sent to the decoding device via a network or a (digital) storage medium. Here, the network can include a broadcast network and / or a communication network. The digital storage medium can include various storage media such as USB, SD, CD, DVD, Blu-ray, HDD, SSD, etc.

[0194] Fig.16 is a flowchart showing the operation of a decoding device according to an embodiment, Fig.17 is a block diagram showing the configuration of a decoding device according to an embodiment.

[0195] Fig.16 The method shown can be Figure 3 or Fig.17 The decoding device shown in FIG. 16 is executed. Steps S1610 and S1620 may be performed by Figure 3 The entropy decoder 310 shown in FIG. 16 is executed. In addition, step S1630 may be performed by Figure 3 The entropy adder 340 shown in FIG. 1 is executed. In addition, the operations according to steps S1610 to S1630 are based on the reference Figures 1 to 13 Therefore, the description and reference are omitted or briefly described. Figures 1 to 13 The description of the specification overlaps the detailed description.

[0196] The decoding device according to the embodiment may obtain image information including segmentation information and residual information of the current picture from the bitstream (step S1610). For example, the segmentation information may include sub-picture information, slice information and / or tile information of the current picture. The sub-picture information may include information of at least one sub-picture included in the current picture, and the slice information may include at least one slice included in the current picture. In addition, the tile information may include at least one tile included in the current picture. In addition, the image information may include residual information, and the residual information may represent the quantized transform coefficients of the residual samples. In addition, the image information may include prediction information, and the prediction information may include information for an inter-prediction mode or an intra-prediction mode performed in the current picture.

[0197] The decoding device according to the embodiment may derive a partition structure of the current picture including at least one slice (step S1620). For example, the entropy decoder 310 of the decoding device may derive at least one sub-picture included in the current picture based on the sub-picture information included in the partition information. For example, the entropy decoder 310 of the decoding device may derive at least one slice included in the current picture based on the slice information included in the partition information. For example, the entropy decoder 310 of the decoding device may derive the partition structure of the current picture based on the sub-picture information and the slice information of the current picture.

[0198] The decoding device according to the embodiment may decode the current picture based on the partition structure (step S1630). For example, the entropy decoder 310 of the decoding device may generate a reconstructed block or a reconstructed picture based on at least one slice. For example, the residual processor 320 of the decoding device may derive the residual sample of the current block based on the residual information of the current block included in the at least one slice. Alternatively, the predictor 330 of the decoding device may derive the prediction sample by performing an inter-frame prediction mode or an intra-frame prediction mode on the current picture based on the prediction information received through the bitstream. The adder 340 of the decoding device may generate a reconstructed block by adding the prediction sample and the residual sample. Alternatively, the adder 340 of the decoding device may reconstruct the current picture based on the residual sample.

[0199] For example, the image information may include a first flag related to the presence of sub-picture information and a second flag related to whether the sub-picture includes only one slice. For example, the value of the first flag may correspond to zero, and the value of the second flag may correspond to 1.

[0200] For example, in a case where the value of the first flag is zero and the value of the second flag is 1, the number of slices included in the current picture may be derived to be equal to 1.

[0201] For example, the first flag related to the presence of the sub-picture information may be included in the SPS (Sequence Parameter Set) of the image information.

[0202] For example, the second flag related to whether the sub-picture includes only one slice may be included in the PPS (Picture Parameter Set) of the image information.

[0203] For example, the image information may include a third flag related to the number of slices included in the current picture, and the third flag may be included in the PPS of the image information.

[0204] In addition, for example, the image information may include a fourth flag related to the number of sub-pictures included in the current picture, and the flag related to the number of sub-pictures included in the current picture may be included in the SPS of the image information.

[0205] In addition, for example, in the case where the value of the first flag is zero, the number of sub-pictures present in each of all pictures of the SPS of the reference image information can be derived to be equal to 1.

[0206] Although the method has been described based on a flowchart that lists steps or blocks in sequence in the above-mentioned embodiments, the steps of this document are not limited to a specific order, and specific steps can be performed in different steps or in a different order or simultaneously relative to the above-mentioned steps. In addition, it will be understood by a person of ordinary skill in the art that the steps in the flowchart are not exclusive, and another step may be included therein, or one or more steps in the flowchart may be deleted without affecting the scope of the present disclosure.

[0207] The above-mentioned method according to the present disclosure may be in the form of software, and the encoding device and / or decoding device according to the present disclosure may be included in a device for performing image processing (e.g., TV, computer, smart phone, set-top box, display device, etc.).

[0208] When the embodiments of the present disclosure are implemented by software, the above-mentioned methods can be implemented by modules (processing or functions) that perform the above-mentioned functions. The module can be stored in a memory and executed by a processor. The memory can be installed inside or outside the processor and can be connected to the processor via various well-known devices. The processor may include an application-specific integrated circuit (ASIC), other chipsets, logic circuits and / or data processing devices. The memory may include a read-only memory (ROM), a random access memory (RAM), a flash memory, a memory card, a storage medium and / or other storage devices. In other words, according to the embodiments of the present disclosure, it can be implemented and executed on a processor, a microprocessor, a controller or a chip. For example, the functional units illustrated in the corresponding figures can be implemented and executed on a computer, a processor, a microprocessor, a controller or a chip. In this case, information about the implementation (e.g., information about instructions) or an algorithm can be stored in a digital storage medium.

[0209] In addition, the decoding device and the encoding device of the embodiment of the present document can be included in a multimedia broadcast transceiver, a mobile communication terminal, a home theater video device, a digital theater video device, a surveillance camera, a video chat device, a real-time communication device such as video communication, a mobile streaming device, a storage medium, a camera, a video on demand (VoD) service provider, an over-the-top (OTT) video device, an Internet streaming service provider, a 3D video device, a virtual reality (VR) device, an augmented reality (AR) device, an image phone video device, a vehicle terminal (e.g., a vehicle (including an autonomous vehicle) terminal, an aircraft terminal or a ship terminal) and a medical video device; and can be used to process image signals or data. For example, an OTT video device can include a game console, a Blueray player, a networked TV, a home theater system, a smart phone, a tablet PC, and a digital video recorder (DVR).

[0210] In addition, the processing method of the application of this document can be generated in the form of a program executed by a computer and can be stored in a computer-readable recording medium. The multimedia data with a data structure according to this document can also be stored in a computer-readable recording medium. The computer-readable recording medium includes all types of storage devices and distributed storage devices storing computer-readable data. The computer-readable recording medium may include, for example, a blue disc (BD), a universal serial bus (USB), a ROM, a PROM, an EPROM, an EEPROM, a RAM, a CD-ROM, a magnetic tape, a floppy disk, and an optical data storage device. The computer-readable recording medium also includes a medium implemented in the form of a carrier wave (e.g., transmission on the Internet). In addition, the bit stream generated by the encoding method can be stored in a computer-readable recording medium, or can be transmitted through a wired or wireless communication network.

[0211] In addition, the embodiments of the present document may be implemented as a computer program product using a program code, and the program code may be executed by a computer according to the embodiments of the present document. The program code may be stored on a computer readable carrier.

[0212] Fig.18 An example of a content streaming system to which the embodiments disclosed in this document can be applied is shown.

[0213] Reference Fig.18 The content streaming system to which the embodiments of this document are applied may basically include an encoding server, a streaming server, a network server, a media storage, a user device, and a multimedia input device.

[0214] The encoding server is used to compress the content input from the multimedia input device such as a smart phone, a camera, a camcorder, etc. into digital data, generate a bit stream, and transmit it to the streaming server. As another example, in the case where the multimedia input device such as a smart phone, a camera, a camcorder, etc. directly generates a bit stream, the encoding server can be omitted.

[0215] The bitstream may be generated by the encoding method or the bitstream generating method to which the embodiments of this document are applied, and the streaming server may temporarily store the bitstream during the process of transmitting or receiving the bitstream.

[0216] The streaming server transmits multimedia data to the user device based on the user's request through the network server, which acts as a tool to inform the user of what services exist. When the user requests the service the user wants, the network server transfers the request to the streaming server, and the streaming server transmits the multimedia data to the user. In this regard, the content streaming system may include a separate control server, and in this case, the control server is used to control the commands / responses between the various devices in the content streaming system.

[0217] The streaming server may receive content from a media storage and / or an encoding server. For example, in the case where content is received from an encoding server, the content may be received in real time. In this case, the streaming server may store the bitstream for a predetermined period of time to smoothly provide a streaming service.

[0218] For example, user devices may include mobile phones, smart phones, laptop computers, digital broadcast terminals, personal digital assistants (PDAs), portable multimedia players (PMPs), navigation, tablet PCs, tablet PCs, ultrabooks, wearable devices (e.g., watch-type terminals (smart watches), glasses-type terminals (smart glasses), head-mounted displays (HMDs)), digital TVs, desktop computers, digital signage, etc.

[0219] Each server in the content streaming system may be operated as a distributed server, and in this case, data received by each server may be processed in a distributed manner.

[0220] The claims of the present disclosure may be combined in various ways. For example, the technical features in the method claims of the present disclosure may be combined to be implemented or performed in a device, and the technical features in the device claims may be combined to be implemented or performed in a method. Furthermore, the technical features in the method claims and the device claims may be combined to be implemented or performed in a device. Furthermore, the technical features in the method claims and the device claims may be combined to be implemented or performed in a method.

Claims

1. A decoding device for image decoding, the decoding device comprising: Memory; as well as at least one processor, the at least one processor connected to the memory, the at least one processor configured to: Obtaining segmentation information and residual information for a current picture through a bitstream, wherein the segmentation information includes a first flag related to the existence of sub-picture information and a second flag related to whether each sub-picture in the current picture includes only one slice; deriving a segmentation structure of the current picture; and Decoding the current picture based on the segmentation structure, The segmentation structure of the current picture is derived based on the following operations: deriving at least one slice included in the current picture based on the segmentation information for the current picture, and A plurality of coding units CU are derived from each of the coding tree units CTU included in the current picture, wherein the CU is related to the current block to be decoded, The current picture is decoded based on the following operations: deriving residual samples for the current block based on the residual information for the current block included in the at least one slice, and reconstructing the current picture based on the residual samples, Wherein, based on the value of the first flag being equal to 0 and the value of the second flag being equal to 1, all CTUs in the current picture are included in one slice.

2. A coding device for image coding, the coding device comprising: Memory; as well as at least one processor, the at least one processor connected to the memory, the at least one processor configured to: Split the current image into at least one slice; deriving a plurality of coding units CU from each of the coding tree units CTU included in the current picture, wherein the CU is related to a current block to be decoded; Generating segmentation information of the current picture based on the at least one slice; deriving residual samples for the current block included in the at least one slice; generating residual information for the current block based on the residual samples; and encoding the image information for the current picture including the segmentation information and the residual information, The segmentation information includes a first flag related to the existence of sub-picture information and a second flag related to whether each sub-picture in the current picture includes only one slice, and Wherein, based on the value of the first flag being equal to 0 and the value of the second flag being equal to 1, all CTUs in the current picture are included in one slice.

3. A device for transmitting data for an image, the device comprising: at least one processor configured to obtain a bitstream for the image, wherein the bitstream is generated based on the following operations: partitioning a current picture into at least one slice, deriving a plurality of coding units CU from each of coding tree units CTU included in the current picture, wherein the CU is related to a current block to be decoded, generating partition information of the current picture based on the at least one slice, deriving residual samples for the current block included in the at least one slice, generating residual information for the current block based on the residual samples, and generating the bitstream by encoding image information for the current picture including the partition information and the residual information; and a transmitter configured to transmit the data including the bit stream, The segmentation information includes a first flag related to the existence of sub-picture information and a second flag related to whether each sub-picture in the current picture includes only one slice, and Wherein, based on the value of the first flag being equal to 0 and the value of the second flag being equal to 1, all CTUs in the current picture are included in one slice.

Images