Image / video compiling method and device

Abstract

The invention relates to an image / video coding method and device. A video decoding method performed by a video decoding device according to the present document may comprise the steps of: parsing, from a bitstream, number information on the number of slices having a height specifically signaled within a tile of a current picture; parsing, on the basis of the digital information, height information on the height of a slice having a height specifically signaled from the bitstream; deriving a number of slices within the tile based on the number information and the height information; generating a prediction sample by performing at least one of intra prediction and inter prediction on a current block of the current picture based on the slices within the tile; and generating a reconstructed sample based on the prediction sample.

Description

[0001] This application is a divisional application of the patent application with the application number 202080091857.2 (international application number PCT / KR2020 / 016884), the international filing date of which is November 26, 2020, and the invention title of which is "Image / Video Compilation Method and Apparatus", and was filed on July 5, 2022. Technical Field

[0002] The present disclosure relates to a method and apparatus for compiling an image / video. Background Art

[0003] Recently, the demand for high-resolution, high-quality images / videos such as 4K or 8K or higher ultra-high definition (UHD) images / videos has been increasing in various fields. As the resolution or quality of images / videos becomes higher, a relatively larger amount of information or bits is sent compared to conventional image / video data. Therefore, if image / video data is transmitted via a medium such as an existing wired / wireless broadband line or stored in a conventional storage medium, it is easy to increase the costs for transmission and storage.

[0004] In addition, the interest and demand for virtual reality (VR) and artificial reality (AR) content and immersive media such as holograms are increasing day by day; and the broadcasting of images / videos (e.g., game images / videos) that exhibit image / video characteristics different from actual images / videos is also increasing.

[0005] Therefore, highly efficient image / video compression technologies are needed to effectively compress, transmit, store, or play high-resolution, high-quality images / videos that exhibit various characteristics as described above. Summary of the Invention

[0006] Technical Problem

[0007] The technical objective of the present disclosure is to provide a method and device for increasing the compilation efficiency of an image / video.

[0008] Another technical objective of the present disclosure is to provide a method and device for effectively signaling information about slices within a tile.

[0009] Yet another technical objective of the present disclosure is to provide a method and device for reducing signaling overhead when delivering (or transmitting) information about slices within a tile.

[0010] Yet another technical objective of the present disclosure is to provide a method and device for effectively delivering (or transmitting) information related to the number and height of slices within a tile.

[0011] Another technical object of the present disclosure is to provide a method and apparatus for more effectively signaling information related to the height of corresponding slices when two or more slices have the same height within a tile.

[0012] Technical solution

[0013] According to an embodiment of the present disclosure, there is provided a video decoding method performed by a video decoding apparatus. The method may include the following steps: parsing, from a bitstream, quantity information related to the number of slices within a tile of a current picture that have their height signaled explicitly; deriving the number of slices within the tile based on the quantity information and height information; generating a prediction sample by performing at least one of intra prediction or inter prediction on a current block of the current picture based on the slices within the tile; and generating a reconstructed sample based on the prediction sample, wherein the height information may include the same number of syntax elements as the value of the quantity information, wherein based on the quantity information value being equal to n, the height of the 0th slice to the (n - 1)th slice within the tile may be derived based on the syntax elements, wherein the height of the nth slice within the tile may be derived based on the height of the (n - 1)th slice, and wherein the height of the last slice within the tile may be derived based on the remaining height after subtracting the heights of the other slices within the tile from the height of the tile.

[0014] According to another embodiment of the present disclosure, there is provided a video encoding method performed by a video encoding apparatus. The method may include the following steps: deriving slices within a tile of a current picture; generating prediction related information and a prediction sample by performing at least one of intra prediction or inter prediction based on the derived slices; generating residual information based on the prediction sample; generating quantity information related to the number of slices within the tile that have their height signaled explicitly and height information related to the height of each slice that has its height signaled explicitly based on the derived slices; and encoding picture information including the prediction related information, the residual information, the quantity information, and the height information, wherein based on the quantity information value being equal to n, the height information may indicate the height of the 0th slice to the (n - 1)th slice within the tile, wherein the height of the nth slice within the tile is derived based on the height of the (n - 1)th slice, and wherein the height of the last slice within the tile may be derived based on the remaining height after subtracting the heights of the other slices within the tile from the height of the tile.

[0015] According to another embodiment of the present disclosure, there is provided a computer-readable digital recording medium having information stored therein that causes a video decoding method to be performed by a video decoding device. The video decoding method may include the steps of: parsing, from image information, quantity information related to the number of slices each of which has its height explicitly signaled within a tile of a current picture; parsing, based on the quantity information, from the image information, height information related to the height of each slice having its height explicitly signaled; deriving the number of slices within the tile based on the quantity information and the height information; generating a prediction sample for a current block of the current picture by performing at least one of intra prediction or inter prediction based on the slices within the tile; and generating a reconstructed sample based on the prediction sample, wherein the height information may include the same number of syntax elements as the value of the quantity information, wherein based on the value of the quantity information being equal to n, the height of the 0th slice to the (n - 1)th slice within the tile may be derived based on the syntax elements, wherein the height of the nth slice within the tile may be derived based on the height of the (n - 1)th slice, and wherein the height of the last slice within the tile may be derived based on the remaining height after subtracting the heights of the other slices within the tile from the height of the tile.

[0016] Effects of the present invention

[0017] According to an embodiment of the present disclosure, the overall compression efficiency of an image / video can be enhanced.

[0018] According to an embodiment of the present disclosure, information regarding slices within a tile can be signaled effectively.

[0019] According to an embodiment of the present disclosure, signaling overhead can be reduced when delivering (or transmitting) information regarding slices within a tile.

[0020] According to an embodiment of the present disclosure, information related to the number and height of slices within a tile can be signaled effectively.

[0021] According to an embodiment of the present disclosure, when two or more slices have the same height within a tile, signaling for the slices having the same height can be skipped. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Schematically shows an example of a video / image compiling system to which an embodiment of the present disclosure can be applied.

[0023] Figure 2 Is a diagram schematically illustrating the configuration of a video / image encoding device to which an embodiment of the present disclosure can be applied.

[0024] Figure 3 Is a diagram schematically illustrating the configuration of a video / image decoding device to which an embodiment of the present disclosure can be applied.

[0025] Figure 4 An example of a video / image encoding method based on intra prediction is shown.

[0026] Figure 5 An example of a video / image decoding method based on intra prediction is shown.

[0027] Figure 6 An example of a video / image encoding method based on inter prediction is shown.

[0028] Figure 7 An example of a video / image decoding method based on inter prediction is shown.

[0029] Figure 8 and Figure 9 respectively show general examples of a video / image encoding method and related components according to an embodiment of the present disclosure.

[0030] Figure 10 and Figure 11 respectively show general examples of a video / image decoding method and related components according to an embodiment of the present disclosure.

[0031] Figure 12 An example of a content streaming system to which an embodiment of the present disclosure can be applied is shown. Detailed Description

[0032] The disclosure of the present disclosure can be modified in various forms, and its specific embodiments will be described and illustrated in the drawings. The terms used in the present disclosure are only used to describe specific embodiments and are not intended to limit the methods disclosed in the present disclosure. Singular expressions include the expression of "at least one" as long as it is clearly interpreted differently. Terms such as "including" and "having" are intended to indicate the presence of features, quantities, steps, operations, elements, components or combinations thereof used in the document, and thus it should be understood that the possibility of the presence or addition of one or more different features, quantities, steps, operations, elements, components or combinations thereof is not excluded.

[0033] This document relates to video / image compilation. For example, the methods / embodiments disclosed in this document can be applied to the methods disclosed in the general video compilation (VVC) standard. In addition, the methods / embodiments disclosed in this document can be applied to the basic video compilation (EVC) standard, the AOMedia Video 1 (AV1) standard, the second-generation audio-visual compilation standard (AVS2), or the next-generation video / image compilation standard (e.g., H.267, H.268, etc.).

[0034] Various embodiments related to video / image compilation are presented in this document, and the embodiments can be combined with each other unless otherwise specified.

[0035] In addition, each configuration of the drawings described in this document is an independent illustration for explaining the functions of features that are different from each other, and does not mean that each configuration is implemented by mutually different hardware or different software. For example, two or more configurations can be combined to form one configuration, and one configuration can also be divided into multiple configurations. Embodiments of combining and / or separating configurations are included within the scope of the disclosure of this disclosure without departing from the gist of the disclosed method of this disclosure.

[0036] In this document, the terms " / " and "," should be interpreted as indicating "and / or". For example, the expression "A / B" can mean "A and / or B". In addition, "A, B" can mean "A and / or B". In addition, "A / B / C" can mean "at least one of A, B, and / or C". In addition, "A / B / C" can mean "at least one of A, B, and / or C".

[0037] In addition, in the document, the term "or" should be interpreted as indicating "and / or". For example, the expression "A or B" can include 1) only A, 2) only B, and / or 3) both A and B. In other words, the term "or" in this document should be interpreted as indicating "additionally or alternatively".

[0038] In addition, the parentheses used in this specification can mean "for example". Specifically, in the case of the expression "prediction (intra prediction)", it can indicate that "intra prediction" is presented as an example of "prediction". In other words, the term "prediction" in this specification is not limited to "intra prediction", and can indicate that "intra prediction" is presented as an example of "prediction". In addition, even in the case of the expression "prediction (i.e., intra prediction)", it can also indicate that "intra prediction" is presented as an example of "prediction".

[0039] In this document, the technical features separately explained in one drawing can be implemented separately or simultaneously.

[0040] Hereinafter, embodiments of this document will be described in detail with reference to the drawings. In addition, in all the drawings, the same reference numerals can be used to indicate the same elements, and the same description of the same elements will be omitted.

[0041] Figure 1 An example of a video / image compilation system to which embodiments of this disclosure can be applied is illustrated.

[0042] Refer to Figure 1 , the video / image compilation system can include a first device (source device) and a second device (receiving device). The source device can send the encoded video / image information or data in the form of a file or a stream to the receiving device through a digital storage medium or a network.

[0043] 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.

[0044] The video source may obtain video / images through processes such as capturing, synthesizing, or generating video / images. 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 video / images, etc. For example, the video / image generating device may include a computer, a tablet computer, and a smart phone, and may (electronically) generate video / images. For example, virtual video / images may be generated by a computer or the like. In this case, the video / image capturing process may be replaced by a process of generating relevant data.

[0045] The encoding device may encode the input video / images. For compression and compilation efficiency, the encoding device may perform a series of processes such as prediction, transformation, and quantization. The encoded data (encoded video / image information) may be output in the form of a bitstream.

[0046] The transmitter may send the encoded image / image information or data output in the form of a bitstream to the receiver of the receiving device in the form of a file or a stream through 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 elements for generating a media file in a predetermined file format and may include elements for transmission through a broadcast / communication network. The receiver may receive / extract the bitstream and send the received bitstream to the decoding device.

[0047] The decoding device may decode the video / images by performing a series of processes such as dequantization, inverse transformation, and prediction corresponding to the operations of the encoding device.

[0048] The renderer may render the decoded video / images. The rendered video / images may be displayed through the display.

[0049] In this document, video may refer to a series of images over a period of time. A picture typically refers to a unit representing an image at a specific time frame, and a slice / tile refers to a unit that forms part of a picture in terms of compilation. A slice / tile can include one or more Compilation Tree Units (CTUs). A picture can be composed of one or more slices / tiles. A picture can be composed of one or more tile groups. A tile group can include one or more tiles. A brick can represent a rectangular region of CTU rows within a tile in a picture. A tile can be partitioned into multiple bricks, each consisting of one or more CTU rows within that tile. A tile that is not partitioned into multiple bricks can also be referred to as a brick. Tile scanning is a specific sequential ordering of the CTUs of a partitioned picture, where the CTUs are sequentially ordered in the CTU raster scan of a tile, the tiles within a tile are sequentially ordered in the tile raster scan of the tile, and the tiles in a picture are sequentially ordered in the tile raster scan of the picture. A tile is a rectangular region of CTUs within a specific tile column and a specific tile row in a picture. A tile column is a rectangular region of CTUs, whose height is equal to the height of the picture and whose width is specified by a syntax element in the picture parameter set. A tile row is a rectangular region of CTUs, whose height is specified by a syntax element in the picture parameter set and whose width is equal to the width of the picture. Tile scanning is a specific sequential ordering of the CTUs of a partitioned picture, where the CTUs are sequentially ordered in the CTU raster scan of a tile, and the tiles in a picture are sequentially ordered in the tile raster scan of the picture. A slice includes an integer number of tiles of a picture, which can be exclusively contained in a single NAL unit. A slice can be composed of multiple complete tiles, or only of a consecutive sequence of complete tiles of a single tile. In this document, tile groups and slices can be used interchangeably. For example, in this document, a tile group / tile group header can be referred to as a slice / slice header.

[0050] A pixel or pel can mean the smallest unit that makes up a picture (or image). Additionally, "sample" can be used as a term corresponding to a pixel. A sample typically can represent a pixel or a pixel value, and can represent only the pixel / pixel value of the luminance component or only the pixel / pixel value of the chrominance component.

[0051] A unit may represent a basic unit of image processing. A unit may include at least one of a specific region of a picture and information related to the region. 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 a region. In general, an M×N block may include a set (or array) of samples (or sample array) or transform coefficients having M columns and N rows. Alternatively, a sample may mean a pixel value in the spatial domain, and when such a pixel value is transformed into the frequency domain, it may mean a transform coefficient in the frequency domain.

[0052] In some cases, a unit may be used interchangeably with terms such as a block or a 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 generally may represent a pixel or a pixel value, which may be a pixel / pixel value representing only a luminance component or a pixel / pixel value representing only a chrominance component. A sample may be used as a term corresponding to a pixel or a picture element of a picture (or an image).

[0053] Figure 2 is a diagram schematically illustrating a configuration of a video / image encoding device to which embodiments of the present disclosure may be applied. Hereinafter, a device referred to as a video encoding device may include an image encoding device.

[0054] Referring to Figure 2 , the encoding device 200 includes an image partitioner 210, a predictor 220, a residual processor 230, an entropy encoder 240, an adder 250, a filter 260, and a memory 270. The predictor 220 may include an inter-frame predictor 221 and an intra-frame predictor 222. The residual processor 230 may include a transformer 232, a quantizer 233, a dequantizer 234, and an inverse transformer 235. The residual processor 230 may further include a subtractor 231. The adder 250 may be referred to as a reconstructor or a reconstructed block generator. According to an embodiment, the image partitioner 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 a processor). Additionally, the memory 270 may include a decoded picture buffer (DPB), or may be configured by a digital storage medium. The hardware component may further include the memory 270 as an internal / external component.

[0055] The image partitioner 210 may partition an input image (or picture or frame) input to the encoding device 200 into one or more processing units. For example, the processing unit may be referred to as a coding unit (CU). In this case, the coding unit may be recursively partitioned from a coding tree unit (CTU) or a largest coding unit (LCU) according to a quadtree binary tree ternary tree (QTBTTT) structure. For example, a coding unit may be partitioned into multiple coding units with deeper depths based on a quadtree structure, a binary tree structure, and / or a ternary structure. In this case, for example, the quadtree structure may be applied first, and later the binary tree structure and / or the ternary structure may be applied. Alternatively, the binary tree structure may be applied first. The coding process according to the present disclosure may be performed based on the final coding unit that is no longer partitioned. In this case, depending on the image characteristics and coding efficiency, etc., the largest coding unit may be used as the final coding unit, or if necessary, the coding unit may be recursively partitioned into coding units with deeper depths and the coding unit with an optimal size may be used as the final coding unit. Here, the coding process may include processes of prediction, transformation, and reconstruction (to be described later). As another example, the processing unit may further include a prediction unit (PU) or a transformation unit (TU). In this case, each of the prediction unit and the transformation unit may be partitioned or divided from the above-mentioned final coding unit. The prediction unit may be a unit for sample prediction, and the transformation unit may be a unit for deriving transformation coefficients and / or a unit for deriving a residual signal from the transformation coefficients.

[0056] The encoding device 200 may subtract a prediction signal (prediction block, prediction sample array) output from the inter-frame predictor 221 or the intra-frame predictor 222 from an 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 unit that subtracts the prediction signal (prediction block, prediction sample array) from the input image signal (original block, original sample array) in the encoder 200 may be referred to as the subtractor 231. The predictor may perform prediction on a processing target block (hereinafter, referred to as the current block) and generate a prediction block including the prediction samples of the current block. The predictor may determine whether to apply intra-frame prediction or inter-frame prediction in units of the current block or CU. As will be described later in the description of each prediction mode, the predictor may generate various types of information about the prediction (e.g., prediction mode information) and send the generated information to the entropy encoder 240. The information about the prediction may be encoded by the entropy encoder 240 and output in the form of a bitstream.

[0057] The intra predictor 222 may predict a current block by referring to samples in the current picture. Depending on the prediction mode, the samples referred to may be located near the current block or may be positioned far from the current block. In intra prediction, the prediction mode may include a plurality of non - directional modes and a plurality of directional modes. For example, the non - directional modes may include the DC mode and the planar mode. For example, depending on the level of detail of the prediction direction, the directional modes 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 settings. The intra predictor 222 may use the prediction mode applied to neighboring blocks to determine the prediction mode applied to the current block.

[0058] The inter predictor 221 may derive a predicted block of a 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 transmitted in the inter - prediction mode, the motion information may be predicted in units of blocks, sub - blocks, or samples based on the correlation of the motion information between 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 - prediction direction (L0 prediction, L1 prediction, Bi prediction, etc.) information. In the case of inter - prediction, 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 predictor 221 may configure a motion information candidate list based on 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 - prediction may be performed based on various prediction modes. For example, in the skip mode and the merge mode, the inter predictor 221 may use the motion information of neighboring blocks as the motion information of the current block. In the skip mode, different from the merge mode, a residual signal may not be sent. The motion vector prediction (MVP) mode may indicate the motion vector of the current block by using the motion vector of a neighboring block as a motion vector predictor and signaling the motion vector difference.

[0059] Predictor 220 may generate a prediction signal based on various prediction methods described later. For example, predictor 220 may apply intra prediction or inter prediction to predict a block, and may apply intra prediction and inter prediction simultaneously. This may be referred to as combined inter and intra prediction (CIIP). Additionally, the predictor may be based on the intra block copy (IBC) prediction mode or the palette mode for predicting the block. The IBC prediction mode or the palette mode may be used for image / video compilation of content such as games, e.g., screen content compilation (SCC). IBC basically performs prediction in the current picture, but it may perform similarly to inter prediction in that it derives a reference block in the current picture. That is, IBC may use at least one of the inter prediction techniques described in this document. The palette mode may be regarded as an example of intra compilation or intra prediction. When the palette mode is applied, the sample values in the picture may be signaled based on the information about the palette table and the palette index.

[0060] The prediction signal generated by the predictor (including inter predictor 221 and / or intra predictor 222) may be used to generate a reconstructed signal or may be used to generate a residual signal.

[0061] Transformer 232 may generate transform coefficients by applying a transform technique to the residual signal. For example, the transform technique may include at least one of the following: discrete cosine transform (DCT), discrete sine transform (DST), graph-based transform (GBT), or conditional non-linear transform (CNT). Here, when the relationship information between pixels is illustrated as a graph, GBT means a transform obtained from the graph. CNT means a transform obtained based on a prediction signal generated by using all previously reconstructed pixels. Additionally, the transform process may also be applied to a square pixel block of the same size, or may also be applied to a variable-size block that is not square.

[0062] Quantizer 233 quantizes the transform coefficients and sends the quantized transform coefficients to entropy encoder 240, and entropy encoder 240 encodes the quantized signal (information about the quantized transform coefficients) and outputs the encoded signal as a bitstream. The information about the quantized transform coefficients may be referred to as residual information. Quantizer 233 may rearrange the quantized transform coefficients in block form into a one-dimensional vector form based on the coefficient scan order, and also generate information about the quantized transform coefficients based on the quantized transform coefficients in one-dimensional vector form.

[0063] Entropy encoder 240 may perform various encoding methods such as, for example, Exponential Golomb, Context Adaptive Variable Length Coding (CAVLC), and Context Adaptive Binary Arithmetic Coding (CABAC). Entropy encoder 240 may also encode, either together or separately, information necessary for video / image reconstruction other than the quantized transform coefficients (e.g., values of syntax elements, etc.). The encoded information (e.g., encoded video / image information) may be sent or stored in the form of a bitstream in units of Network Abstraction Layer (NAL). The video / image information may also include information about various parameter sets, such as Adaptation Parameter Set (APS), Picture Parameter Set (PPS), Sequence Parameter Set (SPS), or Video Parameter Set (VPS). Additionally, the video / image information may also include general constraint information. In this document, information signaled / sent from an encoding device to a decoding device and / or syntax elements may be included in the video / image information. The video / image information may be encoded through the aforementioned encoding process and thus included in the bitstream. The bitstream may be sent over a network or may be stored in a digital storage medium. Here, 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 transmission unit (not shown) for sending the signal output from entropy encoder 240 and / or a storage unit (not shown) for storing the signal may be configured as internal / external elements of encoding device 200, or the transmission unit may also be included in entropy encoder 240.

[0064] The quantized transform coefficients output from quantizer 233 may be used to generate a prediction signal. For example, an inverse quantization and inverse transform may be applied to the quantized transform coefficients by inverse quantizer 234 and inverse transform unit 235 to reconstruct a residual signal (residual block or residual samples). Adder 250 may add the reconstructed residual signal to the prediction signal output from inter-frame predictor 221 or intra-frame predictor 222 to generate a reconstructed signal (reconstructed picture, reconstructed block, reconstructed sample array). For example, when applying the skip mode, when there is no residual for the processing target block, the prediction block may be used as the reconstructed block. Adder 250 may be referred to as a restorer or a reconstructed block generator. The generated reconstructed signal may be used for intra-frame prediction of the next processing target block within the current picture, and may also be used for inter-frame prediction of the next picture after filtering, as described below.

[0065] Meanwhile, Luminance Mapping and Chrominance Scaling (LMCS) may also be applied during picture encoding and / or reconstruction processing.

[0066] Filter 260 may improve subjective / objective image quality by applying filtering to the reconstructed signal. For example, filter 260 may generate a modified reconstructed picture by applying various filtering methods to the reconstructed picture and store the modified reconstructed picture in memory 270 (specifically, the DPB of memory 270). For example, the various filtering methods may include deblocking filtering, sample adaptive offset, adaptive loop filter, bilateral filter, etc. Filter 260 may generate various types of information related to the filtering and transmit the generated information to entropy encoder 240, as will be described later in the description of each filtering method. The information related to the filtering may be encoded by entropy encoder 240 and output in the form of a bitstream.

[0067] The modified reconstructed picture sent to memory 270 may be used as a reference picture in inter-frame predictor 221. When inter-frame prediction is applied by the encoding device, prediction mismatch between encoding device 200 and the decoding device may be avoided and encoding efficiency may be improved.

[0068] The DPB of memory 270 may store the corrected reconstructed picture to be used as a reference picture in inter-frame predictor 221. Memory 270 may store the motion information of the blocks from which the motion information in the current picture is derived (or encoded) and / or the motion information of the blocks in the already reconstructed pictures. The stored motion information may be transmitted to inter-frame predictor 221 to be used as the motion information of spatially neighboring blocks or temporally neighboring blocks. Memory 270 may store the reconstructed samples of the reconstructed blocks in the current picture and may transmit the reconstructed samples to intra-frame predictor 222.

[0069] Figure 3 is a diagram for schematically explaining the configuration of a video / image decoding device to which embodiments of the present disclosure may be applied.

[0070] Referring to Figure 3 , decoding device 300 may include entropy decoder 310, residual processor 320, predictor 330, adder 340, filter 350, and memory 360. Predictor 330 may include inter-frame predictor 331 and intra-frame predictor 332. Residual processor 320 may include dequantizer 321 and inverse transformer 321. According to an embodiment, entropy decoding 310, residual processor 320, predictor 330, adder 340, and filter 350 may be configured by hardware components (e.g., a decoder chipset or a processor). Additionally, memory 360 may include a decoded picture buffer (DPB) or may be configured by a digital storage medium. The hardware components may also include memory 360 as an internal / external component.

[0071] When a bitstream including video / image information is input, decoding device 300 may respond to the Figure 2Reconstruct an image according to the process of processing video / image information in the encoding device shown. For example, the decoding device 300 may derive units / blocks based on the block partition related information obtained from the bitstream. The decoding device 300 may perform decoding using the processing units applied to the encoding device. Thus, for example, the processing units for decoding may be compilation units, and the compilation units may be split from the compilation tree units or the largest compilation units 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 compilation units. In addition, the reconstructed image signal decoded and output by the decoding device 300 may be reproduced by a reproduction device.

[0072] The decoding device 300 may receive the signal output from the Figure 2 encoding device in the form of a bitstream, and may decode the received signal by the entropy decoder 310. For example, the entropy decoder 310 may parse the bitstream to derive the information (e.g., video / image information) required for image reconstruction (or picture reconstruction). The video / image information may also include information about various parameter sets, such as the adaptation parameter set (APS), the picture parameter set (PPS), the sequence parameter set (SPS), or the video parameter set (VPS). In addition, the video / image information may also include general constraint information. The decoding device may also decode a picture based on the information about the parameter sets and / or the general constraint information. The information and / or syntax elements signaled / received described later in this document may be decoded through the decoding process and obtained from the bitstream. For example, the entropy decoder 310 may decode the information in the bitstream based on a compilation method such as exponential Golomb compilation, context-adaptive variable length compilation (CAVLC), or context-adaptive binary arithmetic compilation (CABAC), and output the syntax elements required for image reconstruction and the quantization values of the transform coefficients for the residuals. More specifically, the CABAC entropy decoding method may receive the bins corresponding to each syntax element in the bitstream, determine the context model by using the decoding target syntax element information, the decoding information of the decoding target block, or the information of the symbols / bins decoded in the previous stage, and perform arithmetic decoding on the bins by predicting the probability of the appearance of the bins according to the determined context model, and generate symbols corresponding to the values of each syntax element. In this case, the CABAC entropy decoding method may update the context model by using the information of the decoded symbols / bins 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 may be provided to the predictors (the inter-frame predictor 332 and the intra-frame predictor 331), and the residual values (i.e., the quantized transform coefficients and the related parameter information) for which the entropy decoder 310 has performed entropy decoding may be input to the residual processor 320.

[0073] The residual processor 320 may derive a residual signal (residual block, residual sample, residual sample array). Additionally, information regarding filtering among the information decoded by the entropy decoder 310 may be provided to the filter 350. Meanwhile, a receiver (not shown) for receiving a signal output from the encoding device may also be configured as an internal / external component of the decoding device 300, or the receiver may be a component of the entropy decoder 310. Meanwhile, the decoding device according to this 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 following: dequantizer 321, inverse transformer 322, adder 340, filter 350, memory 360, inter-predictor 332, and intra-predictor 331.

[0074] The dequantizer 321 may dequantize the quantized transform coefficients and output the transform coefficients. The dequantizer 321 may rearrange the quantized transform coefficients in a two-dimensional block form. In this case, the rearrangement may be performed based on the coefficient scan order executed in the encoding device. The dequantizer 321 may perform dequantization on the quantized transform coefficients using a quantization parameter (e.g., quantization step information) and obtain the transform coefficients.

[0075] The inverse transformer 322 inversely transforms the transform coefficients to obtain a residual signal (residual block, residual sample array).

[0076] In this document, at least one of quantization / dequantization and / or transformation / inverse transformation may be omitted. When quantization / dequantization is omitted, the quantized transform coefficients may be referred to as transform coefficients. When transformation / inverse transformation is omitted, the transform coefficients may be referred to as coefficients or residual coefficients, or for the sake of consistency in expression, may still be referred to as transform coefficients.

[0077] In this document, the quantized transform coefficients and the transform coefficients may be referred to as transform coefficients and scaled transform coefficients, respectively. In this case, the residual information may include information regarding the transform coefficients, and the information regarding the transform coefficients may be signaled by the residual coding syntax. The transform coefficients may be derived based on the residual information (or information regarding the transform coefficients), and the scaled transform coefficients may be derived by inverse-transforming (scaling) the transform coefficients. The residual samples may be derived based on the inverse-transform (transformation) of the scaled transform coefficients. This may also be applied / expressed in other parts of this document.

[0078] The predictor 330 can perform prediction on the current block and generate a predicted block including the predicted samples of the current block. The predictor can determine whether to apply intra prediction or inter prediction to the current block and determine a specific intra / inter prediction mode based on the information about the prediction output from the entropy decoder 310.

[0079] The predictor 330 can generate a prediction signal based on the following various prediction methods. For example, the predictor can apply intra prediction or inter prediction for predicting a block, and can also apply intra prediction and inter prediction simultaneously. This can be referred to as combined inter and intra prediction (CIIP). Additionally, the predictor can predict a block based on the intra block copy (IBC) prediction mode or the palette mode. The IBC prediction mode or the palette mode can be used for image / video compilation of content such as games, for example, screen content compilation (SCC). IBC can basically perform prediction within the current picture, but can be performed similarly to inter prediction so that a reference block is derived within 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 compilation or intra prediction. When the palette mode is applied, information about the palette table and palette index can be included in the video / image information and signaled.

[0080] The intra predictor 331 can predict the current block by referring to the samples in the current picture. Depending on the prediction mode, the samples referred to can be located near the current block or can be separated from the current block. In intra prediction, the prediction mode can include a plurality of non - directional modes and a plurality of directional modes. The intra predictor 331 can determine the prediction mode applied to the current block by using the prediction mode applied to the adjacent blocks.

[0081] The inter predictor 332 can derive the predicted block of the current block based on the reference block (reference sample array) specified by the motion vector on the reference picture. In this case, in order to reduce the amount of motion information sent in the inter prediction mode, the motion information can be predicted in units of blocks, sub - blocks, or samples based on the correlation of the motion information between the adjacent blocks and the current block. The motion information can include a motion vector and a reference picture index. The motion information can also include information about the inter prediction direction (L0 prediction, L1 prediction, Bi prediction, etc.). In the case of inter prediction, the adjacent blocks can include spatially adjacent blocks existing in the current picture and temporally adjacent blocks existing in the reference picture. For example, the inter predictor 332 can construct a motion information candidate list based on the adjacent blocks and derive the motion vector and / or reference picture index of the current block based on the received candidate selection information. Inter prediction can be performed based on various prediction modes, and the information about the prediction can include information indicating the inter prediction mode used for the current block.

[0082] The adder 340 can generate a reconstructed signal (reconstructed picture, reconstructed block, reconstructed sample array) by adding the obtained residual signal to the prediction signal (prediction block, prediction sample array) output from a predictor (including the inter-frame predictor 332 and / or the intra-frame predictor 331). If there is no residual for the target block to be processed, for example, in the case of applying the skip mode, the prediction block can be used as the reconstructed block.

[0083] The adder 340 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 will be described subsequently, can also be output through filtering or can also be used for inter-frame prediction of the next picture.

[0084] In addition, a luminance mapping with chroma scaling (LMCS) can also be applied to the picture decoding process.

[0085] 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 corrected reconstructed picture by applying various filtering methods to the reconstructed picture, and store the corrected reconstructed picture in the memory 360, specifically, in the DPB of the memory 360. The various filtering methods can include, for example, deblocking filtering, sample adaptive offset, adaptive loop filter, bilateral filter, etc.

[0086] The (modified) reconstructed picture stored in the DPB of the memory 360 can be used as a reference picture in the inter-frame predictor 332. The memory 360 can store the motion information of the blocks from which the motion information within the current picture is derived (decoded) and / or the motion information of the blocks within the already reconstructed pictures. The stored motion information can be transmitted to the inter-frame predictor 260 to be used as the motion information of spatially adjacent blocks or temporally adjacent blocks. The memory 360 can store the reconstructed samples of the reconstructed blocks within the current picture, and transmit the reconstructed samples to the intra-frame predictor 331.

[0087] In this document, the embodiments described in the filter 260, the inter-frame predictor 221, and the intra-frame predictor 222 of the encoding device 200 can be equally applied to or correspond to the filter 350, the inter-frame predictor 332, and the intra-frame predictor 331.

[0088] Meanwhile, the video / image compilation method according to this document can be executed based on the following partitioning structure. Specifically, the above processes of prediction, residual processing ((inverse) transformation and (de)quantization), syntax element compilation, and filtering can be executed according to the CTUs and CUs (and / or TUs and PUs) derived from the partitioning structure. The block partitioning process can be executed by the image partitioner 210 of the above encoding device, and the partitioning-related information can be processed (encoded) by the entropy encoder 240 and can be transmitted to the decoding device in the form of a bitstream. The entropy decoder 310 of the decoding device can derive the block partitioning structure of the current picture based on the partitioning-related information obtained from the bitstream, and based on this, a series of processes for image decoding (e.g., prediction, residual processing, block / picture reconstruction, loop filtering, etc.) can be executed. The CU size and the TU size can be equal to each other, or multiple TUs can exist within the CU region. Meanwhile, the CU size can generally represent the luminance component (sample) compilation block (CB) size. The TU size can generally represent the luminance component (sample) transform block (TB) size. The chrominance component (sample) CB or TB size can be derived based on the luminance component (sample) CB or TB size according to the component ratio according to the color format (chrominance format, e.g., 4:4:4, 4:2:2, 4:2:0, etc.) of the picture / image. The TU size can be derived based on maxTbSize. For example, if the CU size is larger than maxTbSize, multiple TUs (TBs) of maxTbSize can be derived from the CU, and the transformation / inverse transformation can be executed in units of TU (TB). In addition, for example, in the case of applying intra prediction, the intra prediction mode / type can be derived in units of CU (or CB), and the process of deriving neighboring reference samples and generating prediction samples can be executed in units of TU (or TB). In this case, one or more TUs (or TBs) can exist in one CU (or CB) region, and in this case, multiple TUs (or TBs) can share the same intra prediction mode / type.

[0089] In addition, in the video / image compilation according to this document, the image processing unit may have a hierarchical structure. A picture can be partitioned into one or more tiles, blocks, slices, and / or tile groups. A slice may include one or more blocks. A block may include one or more CTU rows within a tile. A slice may include an integer number of blocks of a picture. A tile group may include one or more tiles. A tile may include one or more CTUs. A CTU may be partitioned into one or more CUs. A tile represents a rectangular region of CTUs within a specific tile column and a specific tile row in a picture. According to the raster scan of tiles in a picture, a tile group may include an integer number of tiles. A slice header may carry information / parameters that can be applied to the corresponding slice (blocks in the slice). In the case where the encoding / decoding device has a multi-core processor, the encoding / decoding processes of tiles, slices, blocks, and / or tile groups can be processed in parallel. In this document, a slice or a tile group may be used interchangeably. That is, a tile group header may be referred to as a slice header. Here, a slice may have one of the slice types, including an intra (I) slice, a predictive (P) slice, and a bi-predictive (B) slice. When predicting blocks in an I slice, inter-frame prediction may not be used, and only intra-frame prediction may be used. Of course, even in this case, signaling may be performed by compiling the original sample values without prediction. Regarding blocks in a P slice, intra-frame prediction or inter-frame prediction may be used, and in the case of using inter-frame prediction, only one-way prediction may be used. Meanwhile, regarding blocks in a B slice, intra-frame prediction or inter-frame prediction may be used, and in the case of using inter-frame prediction, bi-prediction can be used to the maximum extent possible.

[0090] The encoding device may determine the tile / tile group, block, slice, and the maximum and minimum compilation unit sizes considering compilation efficiency or parallel processing, or according to the characteristics of the video image (e.g., resolution), and information about them or information that can induce them may be included in the bitstream.

[0091] The decoding device may obtain information representing the tile / tile group, block, and slice of the current picture and whether the CTUs in the tile have been partitioned into multiple compilation units. By obtaining (sending) such information only under specific conditions, efficiency can be enhanced.

[0092] Meanwhile, as described above, an image may include multiple slices, and a slice may include a slice header and slice data. In this case, an image header may be further added for a plurality of slices (a set of slice headers and slice data) in an image. The image header (image header syntax) may include information / parameters that can be commonly applied to the image. The slice header (slice header syntax) may include information / parameters that can be commonly applied to the slices. An Adaptive Parameter Set (APS) or a Picture Parameter Set (PPS) may include information / parameters that can be commonly applied to one or more images. A Sequence Parameter Set (SPS) may include information / parameters that can be commonly applied to one or more sequences. A Video Parameter Set (VPS) may include information / parameters that can be commonly applied to multiple layers. A Decoding Parameter Set (DPS) may include information / parameters that can be commonly applied to the entire video. The DPS may include information / parameters related to the concatenation of a Compiled Video Sequence (CVS).

[0093] In this document, the high-level syntax may include at least one of the APS syntax, PPS syntax, SPS syntax, VPS syntax, DPS syntax, image header syntax, and slice header syntax.

[0094] In addition, for example, information such as the partitioning and configuration of tiles / tile groups / tuples / slices can be configured in an encoding device based on the high-level syntax and then can be delivered (or transmitted) to a decoding device in bitstream format.

[0095] An image may be partitioned into one or more tile rows and one or more tile columns. A tile is a sequence of CTUs that cover a rectangular area of the image. A tile may be partitioned into one or more tuples, and each tuple may be configured by multiple CTU rows. A tile that is not partitioned into multiple tuples may also be referred to as a tuple. However, a tuple that is a subset of a tile is not referred to as a tile. A slice may include multiple tiles or multiple tuples of a tile.

[0096] A video / image encoding process based on inter-frame prediction may generally include, for example, the following.

[0097] Figure 4 An example of a video / image encoding method based on inter-frame prediction is shown.

[0098] Reference Figure 4, S400 can be performed by the intra predictor 222 of the encoding device, and S410 to S430 can be performed by the residual processor 230 of the encoding device. More specifically, S410 can be performed by the subtractor 231 of the encoding device, S420 can be performed by the transformer 232 and quantizer 233 of the encoding device, and S430 can be performed by the dequantizer 234 and inverse transformer 235 of the encoding device. In S400, the prediction information can be derived by the intra predictor 222 and encoded by the entropy encoder 240. The residual information can be derived through S410 and S420, and then the residual information can be encoded by the entropy encoder 240. The residual information is information related to the residual samples. The residual information can include information related to the quantized transform coefficients of the residual samples. As described above, the residual samples can be derived as transform coefficients by the transformer 232 of the encoding device, and the transform coefficients can be derived as quantized transform coefficients by the quantizer 233. The information related to the quantized transform coefficients can be encoded in the entropy encoder 240 through the residual encoding process.

[0099] The encoding device performs intra prediction on the current block (S400). The encoding device derives the intra prediction mode of the current block, and can derive the neighboring reference samples of the current block, and then, the encoding device generates the prediction samples within the current block based on the intra prediction mode and the neighboring reference samples. Here, the processes of determining the intra prediction mode, deriving the neighboring reference samples, and generating the prediction samples can all be performed simultaneously, or any one of the above-mentioned processes can be performed before the other processes. For example, the intra predictor 222 of the encoding device can include a prediction mode / type determination unit, a reference sample derivation unit, and a prediction sample derivation unit. The prediction mode / type determination unit can determine the intra prediction mode / type of the current block, the reference sample derivation unit can derive the neighboring reference samples of the current block, and the prediction sample derivation unit can derive the motion samples of the current block. At the same time, when performing the prediction sample filtering process to be described below, the intra predictor 222 can further include a prediction sample filter. The encoding device can determine the mode applied to the current block among multiple intra prediction modes. The encoding device can compare the rate-distortion (RD) costs for the intra prediction modes and determine the best intra prediction mode for the current block.

[0100] At the same time, the encoding device can perform the prediction sample filtering process. The prediction sample filtering can also be referred to as post-filtering. Among the prediction samples, some or all of the prediction samples can be filtered through the prediction sample filtering process. In some cases, the prediction sample filtering process can be skipped.

[0101] The encoding device derives residual samples for the current block based on prediction samples (S410). The encoding device performs a phase-based comparison of the prediction samples of the original samples from the current block, and then, the encoding device can derive the residual samples.

[0102] The encoding device can derive quantized transform coefficients by performing transform / quantization on the residual samples (S420). Thereafter, the encoding device can derive (modified) residual samples by performing dequantization / inverse transform processing on the quantized transform coefficients again (S430). As described above, the reason for performing dequantization / inverse transform again after performing transform / quantization is to derive the same residual samples as those derived in the decoding device.

[0103] The encoding device can generate a reconstructed block including reconstructed samples for the current block based on the prediction samples and the (modified) residual samples (S440). A reconstructed picture for the current picture can be generated based on the reconstructed block.

[0104] As described above, the encoding device can encode image information including prediction information related to intra prediction (e.g., prediction mode information indicating a prediction mode) and residual information related to intra / residual samples, and then, output the encoded image information in a bitstream format. The residual information can include residual coding syntax. The encoding device can derive quantized transform coefficients by performing transform / quantization on the residual samples. The residual information can include information about the quantized transform coefficients.

[0105] The video / image decoding process based on intra prediction generally can include, for example, the following.

[0106] Figure 5 An example of a video / image decoding method based on intra prediction is shown.

[0107] The decoding device can perform operations corresponding to those performed by the encoding device.

[0108] Reference Figure 5 , S500 to S510 can be performed by the intra predictor 331 of the decoding device, and the prediction information of S500 and the residual information of S530 can be obtained by the entropy decoder 310 of the decoding device from the bitstream. The residual processor 320 of the decoding device can derive residual samples for the current block based on the residual information. More specifically, the dequantizer 321 of the residual processor 320 can derive transform coefficients by performing dequantization based on the quantized transform coefficients derived according to the residual information. And, the inverse transformer 322 of the residual processor can derive residual samples for the current block by performing an inverse transform on the transform coefficients. S540 can be performed by the adder 340 or the reconstructor of the decoding device.

[0109] More specifically, the decoding device may derive an intra prediction mode for the current block based on the received prediction information (S500). The decoding device may derive neighboring reference samples for the current block (S510). The decoding device may generate prediction samples within the current block by performing intra prediction based on the intra prediction mode and the neighboring reference samples (S520). In this case, the decoding device may perform a prediction sample filtering process. Prediction sample filtering may be referred to as post-filtering. Among the prediction samples, some or all of the prediction samples may be filtered through the prediction sample filtering process. In some cases, the prediction sample filtering process may be skipped.

[0110] The decoding device generates residual samples for the current block based on the received residual information (S530). The decoding device may generate reconstructed samples for the current block based on the prediction samples and the residual samples, and may derive a reconstructed block including the reconstructed samples (S540). A reconstructed picture for the current picture may be generated based on the reconstructed block.

[0111] Here, the intra predictor 331 of the decoding device may include a prediction mode / type determination unit, a reference sample derivation unit, and a prediction sample derivation unit. The prediction mode / type determination unit may determine the intra prediction mode for the current block based on the prediction mode information obtained by the entropy decoder 310 of the decoding device, the reference sample derivation unit may derive neighboring reference samples for the current block, and the prediction sample derivation unit may derive prediction samples for the current block. Meanwhile, when performing the above prediction sample filtering process, the intra predictor 331 may further include a prediction sample filter.

[0112] The prediction information may include intra prediction mode information and / or intra prediction type information. The intra prediction mode information may include, for example, flag information (e.g., intra_luma_mpm_flag) indicating whether the most probable mode (MPM) is applied to the current block or whether the remaining mode is applied to the current block. And when the MPM is applied to the current block, the prediction mode information may further include index information (e.g., intra_luma_mpm_idx) indicating one of the intra prediction mode candidates (MPM candidates). The intra prediction mode candidates (MPM candidates) may be configured by an MPM candidate list or an MPM list. Additionally, when the MPM is not applied to the current block, the intra prediction mode information may further include remaining mode information (e.g., intra_luma_mpm_remainder) indicating one of the remaining intra prediction modes that do not include the intra prediction mode candidates (MPM candidates). The decoding device may determine the intra prediction mode for the current block based on the intra prediction mode information. For the above MIP, a separate MPM list may be configured.

[0113] In addition, the intra prediction type information can be implemented in various formats. For example, the intra prediction type information may include intra prediction type index information indicating one of the intra prediction types. As another example, the intra prediction type information may include at least one of the following: reference sample row information (e.g., intra_luma_ref_idx), which indicates whether the MRL is applied to the current block and which nth reference sample row is being applied when the MRL is applied to the current block; ISP flag information (e.g., intra_subpartitions_mode_flag), which indicates whether the ISP is applied to the current block; ISP type information (e.g., intra_subpartitions_split_flag), which indicates the split (or partition) type of the subpartitions when the ISP is applied to the current block; flag information indicating whether PDCP is applied or flag information indicating whether LIP is applied. In addition, the intra prediction type information may include an MIP flag indicating whether MIP is applied to the current block.

[0114] The intra prediction mode information and / or the intra prediction type information can be encoded / decoded using the encoding / decoding methods described in this specification. For example, the intra prediction mode information and / or the intra prediction type information can be encoded / decoded by using entropy encoding (e.g., CABAC, CAVLC) based on truncated (Rice) binary codes.

[0115] Meanwhile, a video / image encoding process based on inter prediction generally may include, for example, the following.

[0116] Figure 6 An example of a video / image encoding method based on inter prediction is shown.

[0117] Reference Figure 6, the encoding device performs inter prediction on the current block (S600). The encoding device may derive an inter prediction mode and motion information of the current block and generate a prediction sample of the current block. Here, the processes of determining the inter prediction mode, deriving the motion information, and generating the prediction sample may all be performed simultaneously, or any one of the above-mentioned processes may be performed before other processes. For example, the inter predictor of the encoding device may include a prediction mode determination unit, a motion information derivation unit, and a prediction sample derivation unit. The prediction mode determination unit may determine a prediction mode for the current block, the motion information derivation unit may derive the motion information of the current block, and the prediction sample derivation unit may derive the prediction sample of the current block. For example, the inter predictor of the encoding device may search for a block similar to the current block within a predetermined area (search area) of a reference picture by motion estimation, and then, the inter predictor of the encoding device may derive a reference block having the smallest difference from the current block or a difference equal to or lower than a predetermined reference criterion from the current block. Based on this difference, a reference picture index indicating the reference picture in which 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 to be applied to the current block among various prediction modes. The encoding device may compare the rate distortion (RD) costs for various prediction modes and determine the best prediction mode for the current block.

[0118] For example, when applying the skip mode or the merge mode to the current block, the encoding device configures a merge candidate list, and among the reference blocks indicated by the merge candidates included in the merge candidate list, a reference block having the smallest difference from the current block or a difference equal to or lower than a predetermined reference criterion from the current block may be derived. 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 then 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.

[0119] As another example, when the (A)MVP mode is applied to the current block, the encoding device configures an (A)MVP candidate list, and a motion vector of a selected motion vector prediction value (mvp) candidate selected from the mvp candidates included in the (A)MVP candidate list can be used as the mvp of the current block. In this case, for example, a motion vector indicating a reference block derived by the above motion estimation can be used as the motion vector of the current block, and among the mvp candidates, the mvp candidate having the smallest difference from the motion vector of the current block can be the selected mvp candidate. A motion vector difference (MVD) can be derived, which is the difference obtained by subtracting the mvp from the motion vector of the current block. In this case, information related to the MVD can be signaled to the decoding device. Additionally, when the (A)MVP mode is applied, the value of the reference picture index can be configured by reference picture index information and can be signaled to the decoding device separately.

[0120] The encoding device can derive a residual sample based on a prediction sample (S610). The encoding device can derive the residual sample by comparing the prediction sample with the original sample of the current block.

[0121] The encoding device encodes image information including prediction information and residual information (S620). The encoding device can output the encoded image information in a bitstream format. The prediction information can be information related to the prediction process, which can include prediction mode information (e.g., skip flag, merge flag, or mode index, etc.) and information related to motion information. The information related to motion information can include candidate selection information (e.g., merge index, mvp flag, or mvp index), which is information for deriving a motion vector. Additionally, the information related to motion information can include the above information about the MVD and / or reference picture index information. Additionally, the information related to motion information can include information indicating whether L0 prediction, L1 prediction, or bi-directional prediction is applied. The residual information is information related to the residual sample. The residual information can include information related to transform coefficients for quantization of the residual sample.

[0122] The output bitstream can be stored in a (digital) storage medium and then delivered to the decoding device, or the output bitstream can be delivered to the decoding device through a network.

[0123] Meanwhile, the above-mentioned encoding device can generate a reconstructed picture (including reconstructed samples and reconstructed blocks) based on a reference sample and a residual sample. Performing this operation enables the encoding device to derive the same prediction result as the prediction result obtained through the prediction process performed in the decoding device, and also because the compilation efficiency can be enhanced accordingly. Therefore, the encoding device can store the reconstructed picture (or reconstructed sample, reconstructed block) in the memory, and can use the stored picture as a reference picture for inter-frame prediction. As described above, processes such as loop filtering can be further applied to the reconstructed picture.

[0124] The video / image decoding process based on inter-frame prediction generally can include, for example, the following.

[0125] Figure 7 An example of a video / image decoding method based on inter-frame prediction is shown.

[0126] The decoding device can perform operations corresponding to the operations performed by the encoding device. The decoding device can perform prediction on the current block based on the received prediction information and can derive a prediction sample.

[0127] More specifically, referring to Figure 7 , the decoding device can determine a prediction mode for the current block (S700) based on the prediction information received from the bitstream. The decoding device can determine which inter-frame prediction mode to apply to the current block based on the prediction mode information within the prediction information.

[0128] For example, it can be determined based on the merge flag whether to apply the merge mode to the current block or whether to determine the (A)MVP mode. Alternatively, an inter-frame prediction mode candidate can be selected from various inter-frame prediction mode candidates based on the merge index. The inter-frame prediction mode candidates can include various inter-frame prediction modes such as skip mode, merge mode, and / or (A)MVP mode, etc.

[0129] The decoding device derives the motion information of the current block based on the determined inter-frame prediction mode (S710). For example, when applying the skip mode or merge mode to the current block, the decoding device configures a merge candidate list that will be described in detail later, and can select a merge candidate from the merge candidates included in the merge candidate list. The selection can be performed based on the above-mentioned merge index. The motion information of the current block can be derived by using the motion information of the selected merge candidate. The motion information of the selected merge candidate can be used as the motion information of the current block.

[0130] As another example, when the (A) MVP mode is applied to the current block, the decoding device configures the (A) MVP candidate list and the motion vector of the selected motion vector prediction value (mvp) candidate selected from the mvp candidates included in the (A) MVP candidate list can be used as the mvp of the current block. The selection can be performed based on the above selection information (mvp flag or mvp index). And, in this case, the MVD of the current block can be derived based on the information about the MVD, and the motion vector of the current block can be derived based on the mvp and MVD of the current block. Additionally, the reference picture index of the current block can be derived based on the reference picture index information. The picture indicated by the reference picture index within the reference picture list related to the current block can be derived as the reference picture, which is referred to for the inter prediction of the current block.

[0131] Meanwhile, the motion information of the current block can be derived without configuring any candidate list, and in this case, the above candidate list configuration can be skipped.

[0132] The decoding device can generate a prediction sample for the current block based on the motion information of the current block (S720). In this case, the decoding device can derive the reference picture based on the reference picture index of the current block, and then, the decoding device can derive the prediction sample of the current block by using the samples of the reference block indicated by the motion vector of the current block within the reference picture. In this case, among the prediction samples of the current block, a prediction sample filtering process can be further performed on all or part of the prediction samples of the current block, which will be described in more detail later.

[0133] For example, the inter predictor of the decoding device can include a prediction mode determination unit, a motion information derivation unit, and a prediction sample derivation unit. The prediction mode determination unit can determine the prediction mode for the current block based on the received prediction mode information, the motion information derivation unit can derive the motion information (motion vector and / or reference picture index, etc.) of the current block based on the received motion information, and the prediction sample derivation unit can derive the prediction sample of the current block.

[0134] The decoding device generates a residual sample for the current block based on the received residual information (S730). The decoding device can generate a reconstructed sample of the current block based on the prediction sample and the residual sample, and generate a reconstructed picture based on the generated reconstructed sample (S740). Thereafter, as described above, a loop filtering process or the like can be further applied to the reconstructed picture.

[0135] Meanwhile, as described above, high-level syntax (HLS) can be compiled / signaled for video / image compilation. The compiled picture can be configured by one or more slices. The parameters describing the compiled picture are signaled within the picture header, and the parameters describing the slice are signaled within the slice header. The picture header is carried in its own NAL unit format. Also, the slice header exists at the start (or beginning) of the NAL unit that includes the payload of the slice (i.e., the slice data).

[0136] Each picture is associated with a picture header. The picture can be configured by different types of slices (intra-compiled slices (i.e., I slices) and inter-compiled slices (i.e., P slices and B slices)). Thus, the picture header can include the syntax elements required for the intra slices of the picture and the inter slices of the picture.

[0137] The picture can be partitioned (or divided) into sub-pictures, tiles, and / or slices. The sub-picture signaling can exist in the sequence parameter set (SPS). Also, the tile and square slice signaling can exist in the picture parameter set (PPS). The raster scan slice signaling can exist in the slice header.

[0138] For example, regarding the partitioning of the picture, the syntax elements shown in Table 1 below can be included in the SPS syntax.

[0139] [Table 1]

[0140]

[0141] The syntax elements shown in Table 2 below can be included in the PPS syntax.

[0142] [Table 2]

[0143]

[0144]

[0145] In Table 2, num_slices_in_tile_minus1[i] + 1 indicates the number of slices within the current tile when the i-th slice includes a subset of CTU rows in a single tile. The value of num_slices_in_tile_minus1[i] should be in the range including 0 to RowHeight[tileY] - 1. Here, tileY is the index of the tile row that includes the i-th slice. When num_slices_in_tile_minus1[i] does not exist in the PPS, the value of num_slices_in_tile_minus1[i] is derived as 0.

[0146] slice_height_in_ctu_minus1[i] + 1 indicates the height of the i-th rectangular slice in CTU rows when the i-th slice includes a subset of CTU rows in a single tile. The value of slice_height_in_ctu_minus1[i] should be in the range including 0 to RowHeight[tileY] - 1. Here, tileY is the index of the tile row including the i-th slice.

[0147] The syntax elements shown in Table 3 below can be included in the slice header syntax.

[0148] [Table 3]

[0149]

[0150] Referring to Tables 1 to 3, in the current tile and slice design, a rectangular slice can include one or more tiles. Alternatively, a rectangular slice can include an integer number (or whole number) of CTU rows within a single tile.

[0151] When a rectangular slice includes an integer (or whole number) of CTU rows within a single tile (which corresponds to the case where a tile is partitioned into two or more slices), in the current signaling, the height of each slice is explicitly signaled. However, this type of signaling is not the best signaling method.

[0152] The layout of slices within a tile can include the case where the height of slices within the tile is uniform except for the last slice, and the case where the height of slices within the tile is non-uniform. When the height of slices within the tile is uniform except for the last slice, since the height of all slices within the tile excluding the last slice is the same, the height of only one slice can be signaled without explicitly signaling the height of each slice. When the height of slices within the tile is non-uniform, the height of each slice within the tile needs to be signaled.

[0153] The following drawings are illustrated to describe detailed examples of this specification. The detailed terms of the devices (or equipment) specified in the drawings or the detailed terms of signals / information are only exemplary. Therefore, the technical features of this specification will not be limited only to the detailed terms used in the following drawings.

[0154] This specification provides the following methods to facilitate solving the above problems. The items of each method can be applied individually or can be applied in combination.

[0155] For example, when a tile includes two or more slices, the heights of multiple slices that are explicitly signaled within a CTU row can be signaled. This can be referred to as the syntax element num_exp_slice_in_tile. In this case, the syntax elements (array of slice_row_height_minus1) for indices from 0 to num_exp_slice_in_tile - 1 can be signaled. This can be signaled as ue(v) or u(v), and the number of bits for signaling such syntax elements can vary according to the number of CTU rows within the tile. Here, ue(v) represents the syntax element coded with 0th order exponential Golomb, and u(v) indicates using v bits, where the value of v varies according to the values of other syntax elements.

[0156] The height of each slice from the first slice to the nth slice within the tile is respectively given the value of slice_row_height_minus1 + 1 from 0 to num_exp_slice_in_tile - 1. Here, n is equal to the number of slices within the tile that are explicitly signaled (num_exp_slice_in_tile).

[0157] Although there are always remaining CTU rows within the tile that are greater than num_exp_slice_in_tile_minus1 + 1 and are finally (explicitly) signaled, new slices are defined within the tile. In other words, there are slices within the tile that are not explicitly signaled. The height of the last slice may be equal to or less than the last signaled num_exp_slice_in_tile_minus1 + 1.

[0158] As another example, when a tile includes two or more slices, the multiple slices included in the tile can be signaled. In this case, a flag indicating whether the heights of each slice within the tile are uniform can be signaled. When the heights of each slice within the tile are uniform, only one slice height can be signaled according to the CTU rows. The height of each slice within the tile can be derived based on the signaled slice height. And when the heights of each slice within the tile are not uniform, the heights of each slice within the tile excluding the last slice can be explicitly signaled.

[0159] In this specification, information about slices and / or tiles may include the information and / or syntax elements disclosed in Tables 1 to 3. Image / video information may include the High-Level Syntax (HLS) disclosed in Tables 1 to 3, and the High-Level Syntax (HLS) may include information related to slices and / or information related to tiles. Information related to slices may include information indicating one or more slices within the current picture, and information related to tiles may include information indicating one or more tiles within the current picture. Tiles including one or more slices and slices including one or more tiles may exist in the picture.

[0160] As an example, in order to represent the partitioning structure of a picture, the syntax shown in Table 4 and the semantics shown in Table 5 may be used for PPS.

[0161] [Table 4]

[0162]

[0163] [Table 5]

[0164]

[0165] Referring to Tables 4 and 5, num_exp_slices_in_tile[i] + 1 represents the number of exp_slice_height_in_ctu_minus1[j] present in the PPS. When num_exp_slices_in_tile[i] does not exist in the PPS, the value of num_exp_slices_in_tile_minus1[i] is derived as 0.

[0166] exp_slice_height_in_ctu_minus1[j] + 1 indicates the height of the j-th rectangular slice explicitly signaled in CTU rows when the i-th slice includes a subset of CTU rows in a single tile. The value of exp_slice_height_in_ctu_minus1[j] should be in the range including 0 to RowHeight[tileY] - 1. Here, tileY is the index of the tile row including the slice.

[0167] That is to say, num_exp_slices_in_tile[i] may be referred to as information (quantity information) about the number of slices whose height is explicitly signaled within the tile of the current picture. And exp_slice_height_in_ctu_minus1[j] may be referred to as information (height information) about the height of each slice whose height is explicitly signaled.

[0168] The quantity information and the height information may be syntax elements compiled by Exponential Golomb.

[0169] The quantity information may be parsed based on information about the width and height of the slices including the tiles. When the tile includes the i-th slice, the width information of the slice including the tile may correspond to the syntax element slice_width_in_tiles_minus1[i], and the height information of the slice including the tile may correspond to the syntax element slice_height_in_tiles_minus1[i]. The i-th slice may be a rectangular slice, and the slices within the tile may also be partitioned into rectangular slices.

[0170] For example, an encoding device may generate the quantity information and the height information based on information about the slices of the current picture. The quantity information and the height information may be included in the picture information and signaled to a decoding device in a bitstream format.

[0171] When parsing the quantity information from the PPS, as shown in Table 4, the decoding device may parse the height information from the PPS based on the quantity information. For example, when the value of the quantity information is equal to n (where n is an integer equal to or greater than 0), the decoding device may parse the height information about n slices (starting from the 0-th slice to the (n - 1)-th slice within the tile) from the PPS. The height information may indicate each of the heights of the 0-th slice to the (n - 1)-th slice in the CTU rows.

[0172] Thereafter, the decoding device may derive the heights of the remaining slices within the tile based on the height of the (n - 1)-th slice. More specifically, the decoding device may derive the heights of the remaining slices within the tile excluding the last slice starting from the n-th slice within the tile as being equal to the height of the (n - 1)-th slice. To this end, the decoding device may compare the remaining height of the tile, which is calculated by subtracting the sum of the heights of the slices from the 0-th slice to the (n - 1)-th slice from the total height of the tile, in order to determine whether the remaining height is equal to or greater than the uniform slice height. Here, the uniform slice may mean a slice having a uniform height (the same height) within the tile. That is, the height of the uniform slice may be the same as the height of the (n - 1)-th slice.

[0173] When the remaining height of the tile is equal to or greater than the height of the unified slice, the height of the n-th slice can be derived as the height of the unified slice. And when the remaining height of the tile is less than the height of the unified slice, the height of the n-th slice can be derived as the remaining height. Additionally, when the remaining height of the tile is equal to or greater than the height of the unified slice, the updated remaining height can be derived by subtracting the height of the n-th slice from the remaining height. And when the updated remaining height is equal to or greater than the height of the unified slice, the decoding device can derive the height of the (n + 1)-th slice as the height of the unified slice. When the updated remaining height is less than the height of the unified slice, the decoding device can derive the height of the (n + 1)-th slice as the updated remaining height. That is, excluding the last slice within the tile, the height of the slices from the n-th slice to the last slice can be derived as the unified height. The height of the last slice can be equal to or less than the height of each unified slice (from the (n - 1)-th slice to the slice immediately before the last slice).

[0174] For example, when a tile includes 5 slices and when the quantity information indicates 3, the height information of the first slice to the third slice within the tile can be parsed from the PPS, and the height of the fourth slice within the tile can be derived to have the same height as the third slice. In this case, the height of the fifth slice can be greater than or less than the height of the fourth slice.

[0175] The decoding device can derive the number of slices within the tile by performing the above scanning process. When the value of the quantity information is greater than 0, the process of deriving the information about the height of each slice within the tile and the information about the number of slices within the tile can be indicated as shown in Table 5 below.

[0176] [Table 6]

[0177]

[0178] In the case of rectangular slices, the list NumCtuInSlice[i] including i in the range from 0 to num_slices_in_pic_minus1 can indicate the number of CTUs within the i-th slice, and the matrix CtbAddrInSlice[i][j] including i in the range from 0 to num_slices_in_pic_minus1 and j in the range from 0 to NumCtuInSlice[i] - 1 indicates the picture raster scan addressing of the j-th CTB within the i-th slice, and can be derived as shown in Table 7 below.

[0179] [Table 7]

[0180]

[0181] As another example, to represent the partitioning structure of a picture, the syntax shown in Table 8 and the semantics shown in Table 9 may be used for PPS.

[0182] [Table 8]

[0183]

[0184] [Table 9]

[0185]

[0186] Referring to Table 8 and Table 9, if the value of uniform_slice_spacing_flag[i] is equal to 1, this indicates that the CTU rows are evenly distributed (or dispersed) across the entire tile and are signaled by using the syntax element uniform_slice_height_in_ctu_minus1[i]. If the value of uniform_slice_spacing_flag[i] is equal to 0, this indicates that the CTU rows may or may not be evenly distributed (or dispersed) across the entire tile and are signaled by using the syntax elements num_slices_in_tile_minus1[i] and slice_height_in_ctu_minus1[i].

[0187] When the value of uniform_slice_spacing_flag[i] is equal to 1, slice_rows_height_in_ctu_minus1[i]+1 indicates the height of the slice excluding the last slice of the tile in terms of CTB. The value of slice_height_in_ctu_minus1[i] should be in the range including 0 to RowHeight[tileY]-1. Here, tileY is the index of the tile row including the slice.

[0188] num_slices_in_tile_minus1[i] + 1 indicates the number of slices within the current slice when the i-th slice includes a subset of CTU rows in a single tile and when the value of uniform_slice_spacing_flag[i] is equal to 0. The value of num_slices_in_tile_minus1[i] should be in the range including 0 to RowHeight[tileY]-1. Here, tileY is the index of the tile row including the i-th slice. When num_slices_in_tile_minus1[i] does not exist, the value of num_slices_in_tile_minus1[i] is derived as 0.

[0189] slice_height_in_ctu_minus1[i] + 1 indicates the height of the i-th rectangular slice in CTU rows when the i-th slice includes a subset of CTU rows in a single tile. The value of slice_height_in_ctu_minus1[i] should be in the range including 0 to RowHeight[tileY] - 1. Here, tileY is the index of the tile row including the i-th slice.

[0190] For example, the encoding device may generate at least one of uniform_slice_spacing_flag, slice_rows_height_in_ctu_minus1, num_slices_in_tile_minus1, and slice_height_in_ctu_minus1 based on information about slices of the current picture.

[0191] When parsing uniform_slice_spacing_flag from the PPS, as shown in Table 8, the decoding device may parse slice_rows_height_in_ctu_minus1 or num_slices_in_tile_minus1 from the PPS based on the value of uniform_slice_spacing_flag. For example, if the value of uniform_slice_spacing_flag is equal to 1, the decoding device may parse slice_rows_height_in_ctu_minus1 from the PPS, and then may export the parsing result as the height of the remaining slices excluding the last slice within the tile based on the value of slice_rows_height_in_ctu_minus1. If the value of uniform_slice_spacing_flag is equal to 0, the decoding device may parse num_slices_in_tile_minus1 and slice_height_in_ctu_minus1 from the PPS, and may export the slices within the tile based on the parsed results.

[0192] For example, variables NumSlicesInTileMinus1[i] and SliceHeightInCtuMinus1[i + k] related to the number information and height information of slices within a tile may be derived as follows. Here, k may be in the range including 0 to NumSlicesInTileMinus1[i].

[0193] [Table 10]

[0194]

[0195] In the case of rectangular slices, the list NumCtuInSlice[i] for i ranging from 0 to num_slices_in_pic_minus1 can indicate the number of CTUs within the i-th slice, and the matrix CtbAddrInSlice[i][j] for i ranging from 0 to num_slices_in_pic_minus1 and j ranging from 0 to NumCtuInSlice[i]-1 indicates the picture raster scan addressing of the j-th CTB within the i-th slice, and can be derived as shown in Table 11 below.

[0196] [Table 11]

[0197]

[0198] Figure 8 and Figure 9 respectively show general examples of a video / image encoding method and related components according to an embodiment of the present disclosure.

[0199] Figure 8 The video / image encoding method disclosed in Figure 2 and Figure 9 can be executed by the (video / image) encoding device 200 disclosed in Figure 8 More specifically, for example, S800 of Figure 8 can be executed by the image partitioner 210 of the encoding device 200, and S810 can be executed by the predictor 220 of the encoding device 200. S820 can be executed by the residual processor 230 of the encoding device 200. And, S830 and S840 can be executed by the entropy encoder 240 of the encoding device 200.

[0200] More specifically, referring to Figure 8 and Figure 9, the image partitioner 210 of the encoding device may derive slices within the tiles of the current picture (S800). For example, the image partitioner 210 may partition the input image (or picture, frame) into one or more CUs. The input image may include one or more pictures. A picture may be partitioned into one or more tiles, blocks, slices, and / or tile groups. A slice may include one or more blocks, tiles, and / or tile groups. A block may include one or more CTU rows. A tile group may include one or more tiles. A tile may include one or more CTUs. A CTU may be partitioned into one or more CUs. When a specific slice within the current picture is a rectangular slice, the image partitioner 210 may partition the rectangular slice into multiple tiles, and among the multiple tiles, the image partitioner 210 may partition at least one tile, and then derive multiple rectangular slices.

[0201] The predictor 220 of the encoding device may perform at least one of intra prediction or inter prediction on the current block based on the slices derived in the image partitioner 210, and then may generate a prediction sample (predicted block) and prediction-related information of the current block (S810). The predictor 220 may determine whether intra prediction is being applied, or whether inter prediction is being applied in the current block or CU unit. The predictor 220 may deliver various information related to prediction (prediction-related information) to the entropy encoder 240. Here, the prediction-related information may include information related to the inter prediction mode and information related to the intra prediction mode. When the prediction mode of the current block is the inter prediction mode, the prediction sample may be generated in the inter predictor 221 of the predictor 220. And when the prediction mode of the current block is the intra prediction mode, the prediction sample may be generated in the intra predictor 222 of the predictor 220.

[0202] The residual processor 230 of the encoding device may generate residual samples and residual information based on the prediction samples generated by the predictor 220 and the original picture (original block, original sample) (S820). Here, the residual information is information related to the residual samples, and the residual information may include information related to the (quantized) transform coefficients for the residual samples.

[0203] The adder (or reconstructor) of the encoding device may generate reconstructed samples (reconstructed picture, reconstructed block, reconstructed sample array) by adding the prediction samples generated in the residual processor 230 to the prediction samples generated in the inter predictor 221 or the intra predictor 222.

[0204] The entropy encoder 240 of the encoding apparatus may generate information related to a partition based on the partition structure derived in the image partitioner 210. The partition-related information may include information on the number of slices each of which has its height explicitly signaled within a tile (number information) and information on the height of each slice each of which has its height explicitly signaled (height information). For example, the entropy encoder 240 may generate number information related to the number of slices each of which has its height explicitly signaled (provided) within a tile and height information related to the height of each slice each of which has its height explicitly signaled based on the slices derived in the image partitioner 210 (S830). Here, the number information may include the above-described syntax elements num_exp_slices_in_tile and / or num_slices_in_tile_minus1. The height information may include the above-described syntax elements exp_slice_height_in_ctu_minus1, slice_rows_height_in_ctu_minus1, and / or slice_height_in_ctu_minus1.

[0205] The entropy encoder 240 may encode the image information including the partition-related information, which includes the number information and the height information, prediction-related information generated in the predictor 220, and / or residual information generated in the residual processor 230 (S840). The information encoded in the entropy encoder 240 can be output in a bitstream format. The bitstream may be sent to the decoding apparatus via a network or a storage medium.

[0206] For example, the entropy encoder 240 may include image information that includes the syntax element num_exp_slices_in_tile as the number information and the syntax element exp_slice_height_in_ctu_minus1 as the height information based on the above Tables 4 and 5. The height information may indicate the height of each slice each of which has its height explicitly signaled within a tile in units of CTU rows, and for this purpose, the height information may include syntax elements for each slice each of which has its height explicitly signaled. The number of syntax elements included in the image information may be the same as the number information value.

[0207] As another example, entropy encoder 240 may encode picture information including syntax elements uniform_slice_spacing_flag, num_slices_in_tile_minus1, slice_rows_height_in_ctu_minus1, and / or slice_height_in_ctu_minus1 based on Tables 8 and 9 above. The syntax elements num_slices_in_tile_minus1, slice_rows_height_in_ctu_minus1, and slice_height_in_ctu_minus1 may or may not be included in the picture information based on the value of uniform_slice_spacing_flag.

[0208] Entropy encoder 240 may signal the quantity information and height information via a picture parameter set (PPS) within the picture information. In this case, entropy encoder 240 may include the quantity information and / or height information by using the exponential Golomb method.

[0209] Figure 10 and Figure 11 respectively illustrate general examples of a video / image decoding method and related components according to embodiments of the present disclosure.

[0210] Figure 10 The video / image decoding method disclosed in Figure 3 and Figure 11 may be performed by the (video / image) decoding apparatus 300 disclosed in Figure 10 More specifically, for example, S1000 to S1020 of Figure 10 may be performed by the entropy decoder 310 of the decoding apparatus. Figure 10 S1030 of Figure 10 may be performed by the predictor 330 of the decoding apparatus. And,

[0211] Referring to Figure 10 and Figure 11 , the entropy decoder 310 of the decoding apparatus may obtain partition-related information, residual information, prediction-related information (inter / intra prediction difference information, intra prediction mode information, inter prediction mode information, etc.), loop filter-related information, etc. from the bitstream. Here, the partition-related information may include information (quantity information) about the number of each slice that explicitly signals its height among the slices within a tile of the current picture, information (height information) about the height of each slice that explicitly signals its height, etc.

[0212] For example, the entropy decoder 310 may parse, from the bitstream, information (quantity information) related to the number of slices that are each explicitly signaled in height among the slices within a tile of the current picture (S1000), and may parse, from the bitstream based on the quantity information, information (height information) related to the height of each slice that is explicitly signaled in height (S1010). More specifically, the entropy decoder 310 may parse the quantity information and the height information from the picture parameter set (PPS) of the bitstream based on Table 4 above. Here, the quantity information may be parsed based on information regarding the width and height of the slice including the tile. At this time, the slice including the tile and / or the slice within the tile may be a rectangular slice. The quantity information and the height information may be syntax elements encoded in exponential Golomb. The height information may include the syntax elements of each slice that is explicitly signaled in height. The number of syntax elements may be the same as the quantity information value.

[0213] For example, the entropy decoder 310 may parse the syntax elements slice_width_in_tiles_minus1 and slice_height_in_tiles_minus1 from the picture parameter set (PPS) based on Table 4, and the entropy decoder 310 may parse the syntax element num_exp_slices_in_tile from the picture parameter set (PPS) based on the values of the syntax elements slice_width_in_tiles_minus1 and slice_height_in_tiles_minus1. Further, the entropy decoder 310 may parse the number of exp_slice_height_in_ctu_minus1 equivalent to the value of the syntax element num_exp_slices_in_tile from the picture parameter set (PPS).

[0214] When the value of the quantity information is equal to n, the entropy decoder 310 may derive the heights of the 0th slice to the (n - 1)th slice within the tile based on the height information. And the entropy decoder 310 may derive the height of the nth slice within the tile based on the height of the (n - 1)th slice. That is, the height of the nth slice may be derived to be the same as the height of the (n - 1)th slice. Here, the nth slice may not be the last slice within the tile. In other words, the entropy decoder 310 may derive the heights of the remaining slices (slices not explicitly signaled) within the tile excluding the last slice within the tile to have the same height as the (n - 1)th slice. Therefore, except for the last slice within the tile, the heights of the slices from the nth slice to the last slice within the tile may be uniform. The entropy decoder 310 may derive the height of the last slice within the tile based on the remaining height after subtracting the heights of the other slices within the tile from the height of the tile. When deriving the heights of all the slices within the tile, the entropy decoder 310 may derive the number of slices within the tile (S1020). Here, the number of slices within the tile may correspond to the number of slices from the 0th slice to the last slice within the tile.

[0215] The decoding device 300 may decode the current picture based on the quantity information, height information, etc. More specifically, the residual processor 320 of the decoding device may generate residual samples based on the residual information obtained from the entropy decoder 310. The predictor 330 of the decoding device may perform inter prediction and / or intra prediction on the current block in the slice in the picture based on the prediction-related information obtained from the entropy decoder 310 to generate prediction samples (S1030). The adder 340 of the decoding device may generate reconstructed samples based on the prediction samples generated in the predictor 330 and the residual samples generated in the residual processor 320 (S1040). And the adder 340 of the decoding device may generate a reconstructed picture (reconstructed block) based on the reconstructed samples.

[0216] Thereafter, loop filtering processes such as deblocking filtering, SAO, and / or ALF processes may be applied to the reconstructed picture as needed to enhance the subjective / objective picture quality.

[0217] Meanwhile, as another example, the entropy decoder 310 may parse the syntax elements slice_width_in_tiles_minus1 and slice_height_in_tiles_minus1 from the picture parameter set (PPS) of the bitstream based on Table 8, and the entropy decoder 310 may parse the syntax element uniform_slice_spacing_flag from the picture parameter set (PPS) based on the values of the syntax elements slice_width_in_tiles_minus1 and slice_height_in_tiles_minus1. In this case, the entropy decoder 310 may parse the syntax element slice_rows_height_in_ctu_minus1 or parse the syntax element num_slices_in_tile_minus1 from the picture parameter set (PPS) based on the value of the syntax element uniform_slice_spacing_flag. When the value of the syntax element uniform_slice_spacing_flag is equal to 1, the syntax element slice_rows_height_in_ctu_minus1 may be parsed, and when the value of the syntax element uniform_slice_spacing_flag is equal to 0, the syntax element num_slices_in_tile_minus1 may be parsed.

[0218] When the syntax element slice_rows_height_in_ctu_minus1 is parsed, the entropy decoder 310 may derive the height of the remaining slices in the tile excluding the last slice as the value of slice_rows_height_in_ctu_minus1.

[0219] When parsing the syntax element num_slices_in_tile_minus1, the entropy decoder 310 may parse a plurality of syntax elements slice_height_in_ctu_minus1 corresponding to the value of the syntax element num_slices_in_tile_minus1, and may derive these values respectively as the height of each slice in the tile.

[0220] Although the method has been described in the above embodiments based on a flowchart listing steps or blocks in sequence, the steps of the present disclosure are not limited to a specific order, and a certain step may be performed in different steps or in a different order or simultaneously with respect to the above order. In addition, those of ordinary skill in the art should understand 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.

[0221] 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.).

[0222] When implementing the embodiments of the present disclosure in software, the above-mentioned method may be implemented by modules (processes or functions) that execute the above-mentioned functions. The modules may be stored in a memory and executed by a processor. The memory may be installed inside or outside the processor and may be connected to the processor via various well-known devices. The processor may include an application specific integrated circuit (ASIC), other chip sets, 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, the embodiments according to the present disclosure may be implemented and executed on a processor, a microprocessor, a controller, or a chip. For example, the functional units illustrated in the corresponding figures may 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 algorithms may be stored in a digital storage medium.

[0223] In addition, the decoding device and the encoding device applying the embodiments of the present disclosure may be included in a multimedia broadcast transceiver, a mobile communication terminal, a home theater video device, a digital cinema 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 portable 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, an in-vehicle terminal (e.g., a vehicle (including an autonomous vehicle) in-vehicle terminal, an aircraft terminal, or a ship terminal), and a medical video device; and may be used to process image signals or data. For example, the OTT video device may include a game console, a Blueray player, an Internet-connected TV, a home theater system, a smart phone, a tablet PC, and a digital video recorder (DVR).

[0224] In addition, the processing method according to the embodiments of the present disclosure can be generated in the form of a program executable by a computer and can be stored in a computer-readable recording medium. Multimedia data having a data structure according to the embodiments of the present disclosure can also be stored in a computer-readable recording medium. The computer-readable recording medium includes all kinds of storage devices and distributed storage devices storing computer-readable data. The computer-readable recording medium can include, for example, Blu-ray Disc (BD), Universal Serial Bus (USB), ROM, PROM, EPROM, EEPROM, RAM, CD-ROM, magnetic tape, floppy disk, and optical data storage devices. 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 bitstream generated by an encoding method can be stored in a computer-readable recording medium or can be transmitted through a wired or wireless communication network.

[0225] In addition, the embodiments of the present disclosure can be implemented as a computer program product based on program code, and the program code can be executed on a computer according to the embodiments of this document. The program code can be stored on a computer-readable carrier.

[0226] Figure 12 An example of a content streaming system to which the embodiments of this document can be applied is shown.

[0227] Reference Figure 12 , a content streaming system to which the embodiments of this document are applied generally can include an encoding server, a streaming server, a web server, a media storage, a user device, and a multimedia input device.

[0228] The encoding server is used to compress the content input from a multimedia input device such as a smart phone, a camera, a portable video camera, etc. into digital data, generate a bitstream, and transmit it to the streaming server. As another example, in the case where a multimedia input device such as a smart phone, a camera, a portable video camera, etc. directly generates a bitstream, the encoding server can be omitted.

[0229] The bitstream can be generated by an encoding method or a bitstream generation method to which the embodiments of the present disclosure can be applied. And the streaming server can temporarily store the bitstream during the process of sending or receiving the bitstream.

[0230] The streaming server transmits multimedia data to the user device via the web server based on the user's request, and the web server serves as a tool to notify the user of what services are available. When the user requests a service that the user wants, the web 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 such a case, the control server is used to control commands / responses between various devices in the content streaming system.

[0231] The streaming server may receive content from a media storage and / or an encoding server. For example, in the case of receiving content from the 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 the streaming service.

[0232] For example, the user device may include a mobile phone, a smartphone, a laptop computer, a digital broadcast terminal, a personal digital assistant (PDA), a portable multimedia player (PMP), a navigation device, a slate PC, a tablet PC, an ultrabook, a wearable device (e.g., a watch-type terminal (smartwatch), a glasses-type terminal (smart glasses), a head-mounted display (HMD)), a digital TV, a desktop computer, a digital signage, etc.

[0233] Each server in the content streaming system may be operated as a distributed server, and in such a case, the data received by each server may be processed in a distributed manner.

Claims

1. A video decoding apparatus, comprising: a memory, and at least one processor, the at least one processor being connected to the memory, the at least one processor being configured to: parse, from a bitstream, quantity information related to the number of specific slices each of which has its height explicitly signaled within a tile of a current picture; parse, based on the quantity information, height information related to the height of each specific slice having its height explicitly signaled, from the bitstream; derive the number of slices within the tile based on the quantity information and the height information; generate prediction samples by performing at least one of intra prediction or inter prediction on a current block of the current picture based on at least one of the slices within the tile; and generate reconstructed samples based on the prediction samples; wherein the height information includes the same number of syntax elements as the number of the specific slices, wherein, based on the number of the specific slices being equal to n, the heights of the 0th slice to the (n-1)th slice within the tile are derived based on the syntax elements, wherein the height of the nth slice within the tile is derived based on the height of the (n-1)th slice, wherein the height of the last slice within the tile is derived based on the remaining height after subtracting the heights of other slices within the tile from the height of the tile, and wherein the syntax elements in the height information represent the height of one of the specific slices in units of CTU rows.

2. The video decoding device according to claim 1, wherein, The number of slices within the tile is equal to the number of slices from the 0th slice to the last slice.

3. The video decoding device according to claim 1, wherein The height of the nth slice is derived to be the same as the height of the (n-1)th slice.

4. The video decoding device according to claim 1, wherein, The heights of the slices within the tile from the nth slice to the slice immediately before the last slice are uniform.

5. The video decoding apparatus according to claim 4, wherein The height of the last slice is less than or equal to the height of the (n-1)th slice.

6. The video decoding apparatus according to claim 1, Among them, wherein the at least one processor is further configured to: compare the remaining height of the tile calculated by subtracting the sum of the heights of the slices from the 0th slice to the (n-1)th slice from the total height of the tile with the height of a uniform slice to determine whether the remaining height is equal to or greater than the height of the uniform slice, wherein the height of the uniform slice is the same as the height of the (n-1)th slice, wherein, based on the remaining height of the tile calculated by subtracting the sum of the heights of the slices from the 0th slice to the (n-1)th slice from the total height of the tile being equal to or greater than the height of the uniform slice, the nth slice having the height of the uniform slice is derived, and wherein, based on the remaining height of the tile calculated by subtracting the sum of the heights of the slices from the 0th slice to the (n-1)th slice from the total height of the tile being less than the height of the uniform slice, the nth slice having the remaining height is derived.

7. The video decoding device according to claim 6, wherein, Based on the remaining height being equal to or greater than the height of the unified slice, an updated remaining height is derived, where the updated remaining height is updated by subtracting the height of the nth slice from the remaining height of the tile, and the remaining height of the tile is calculated by subtracting the sum of the heights of the slices from the 0th slice to the (n - 1)th slice from the total height of the tile. wherein, based on the updated remaining height being equal to or greater than the height of the unified slice, a slice of the (n + 1)th slice having the height of the unified slice is derived, and wherein, based on the updated remaining height being less than the height of the unified slice, a slice of the (n + 1)th slice having the updated remaining height is derived.

8. The video decoding device according to claim 1, wherein, The quantity information and the height information include syntax elements compiled by exponential Golomb.

9. The video decoding device according to claim 1, wherein, The quantity information includes the syntax element num_exp_slices_in_tile, and wherein, the height information includes the syntax element exp_slice_height_in_ctu_minus1.

10. The video decoding device according to claim 1, wherein, The slices within the tile are rectangular slices.

11. The video decoding device according to claim 1, wherein, The quantity information is parsed based on information related to the width and height of the slices including the tile.

12. A video coding apparatus, comprising: a memory, and at least one processor, the at least one processor being connected to the memory, the at least one processor being configured to: derive slices within a tile of a current picture; generate prediction-related information and prediction samples by performing at least one of intra prediction or inter prediction based on at least one of the derived slices; generate residual information based on the prediction samples; generate quantity information related to the quantity of each specific slice within the tile that signals its height explicitly and height information related to the height of each specific slice that signals its height explicitly; and encode image information including the prediction-related information, the residual information, the quantity information, and the height information, wherein, the height information includes the same number of syntax elements as the quantity of the specific slices, wherein, based on the quantity of the specific slices being equal to n, the syntax elements in the height information indicate the heights of the 0th slice to the (n - 1)th slice within the tile, wherein, the height of the nth slice within the tile is represented based on the height of the (n - 1)th slice, wherein, the height of the last slice within the tile is represented based on the remaining height after subtracting the heights of other slices within the tile from the height of the tile, and wherein, the syntax elements in the height information represent the height of one of the specific slices in units of CTU rows.

13. A device for transmitting data for video, the device comprising: a memory; and at least one processor, the at least one processor being connected to the memory, the at least one processor being configured to: Obtain a bitstream for the video, where the bitstream is generated based on: deriving slices within a tile of a current picture, generating prediction-related information and prediction samples by performing at least one of intra prediction or inter prediction based on at least one of the derived slices, generating residual information based on the prediction samples, generating quantity information related to the number of each specific slice whose height is explicitly signaled within the tile and height information related to the height of each of the specific slices whose height is explicitly signaled, and encoding picture information, the picture information including the prediction-related information, the residual information, the quantity information, and the height information; And Transmit the data including the bitstream, where, based on the number of the specific slices being equal to n, the syntax element in the height information indicates the heights of the 0th slice to the (n - 1)th slice within the tile, where the height of the nth slice within the tile is represented based on the height of the (n - 1)th slice, where the height of the last slice within the tile is represented based on the remaining height after subtracting the heights of other slices within the tile from the height of the tile, and where the syntax element in the height information represents the height of one of the specific slices in units of CTU rows.

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