Method and apparatus for removing duplicate syntax in merged data syntax

Abstract

A decoding method performed by a decoding device is provided. [Solution] The decoding method includes the steps of: determining the prediction mode of the current block based on prediction mode information obtained from a bitstream; constructing a merge candidate list based on the prediction mode; deriving motion information of the current block based on the merge candidate list; and generating a prediction sample of the current block based on the motion information, wherein the bitstream includes information on a CIIP availability flag indicating whether or not CIIP is available, and the determination step includes the step of obtaining a regular merge flag from the bitstream based on the CIIP availability flag.

Description

Technical Field

[0001] The present technology relates to a method and apparatus for removing duplicate syntax of merge data syntax in a video / video coding system.

Background Art

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

[0003] Also, in recent years, the interest and demand for immersive media such as VR (Virtual Reality), AR (Artificial Realtiy) content, and holograms have been increasing, and the broadcast of video / video having video characteristics different from real-world video, such as game video, has been increasing.

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

Summary of the Invention

Problems to be Solved by the Invention

[0005] The technical problem of this document is to provide a method and apparatus for improving video coding efficiency.

[0006] Another technical objective of this paper is to provide a method and apparatus for efficiently performing interpretation.

[0007] Another technical objective of this paper is to provide a method and apparatus for removing unnecessary signaling during interpretation.

[0008] Another technical challenge of this paper is to provide a method and apparatus for efficiently signaling information about merge mode during interpretation.

[0009] Another technical objective of this document is to provide a method and apparatus for removing duplicate syntax in merged data syntax. [Means for solving the problem]

[0010] According to one embodiment of this document, a decoding method performed by a decoding device includes the steps of: determining the prediction mode of the current block based on prediction mode information obtained from a bitstream; constructing a merge candidate list based on the prediction mode; deriving motion information of the current block based on the merge candidate list; and generating a prediction sample of the current block based on the motion information, wherein the bitstream includes information on a CIIP availability flag indicating whether or not CIIP (combined inter-picture merge and intra-picture prediction) is available, and the determination step includes the step of obtaining a regular merge flag from the bitstream based on the CIIP availability flag.

[0011] According to other embodiments of this document, an encoding method performed by an encoding device includes the steps of: determining the prediction mode of the current block; constructing a merge candidate list based on the prediction mode; deriving motion information of the current block based on the merge candidate list; deriving a prediction sample of the current block based on the motion information; deriving a residual sample based on the prediction sample; and encoding video information including information about the prediction mode generated based on the prediction mode and residual information generated based on the residual sample, wherein the video information includes information about a CIIP availability flag indicating whether CIIP is available or not, and the video information includes a regular merge flag based on the CIIP availability flag.

[0012] According to another embodiment of this document, a computer-readable digital storage medium includes information causing a decoding device to perform a decoding method, the decoding method comprising the steps of: determining the prediction mode of a current block based on prediction mode information obtained from a bitstream; constructing a merge candidate list based on the prediction mode; deriving motion information of the current block based on the merge candidate list; and generating a prediction sample of the current block based on the motion information, wherein the bitstream includes information on a CIIP availability flag indicating whether CIIP (combined inter-picture merge and intra-picture prediction) is available, and the determining step includes obtaining a regular merge flag from the bitstream based on the CIIP availability flag. [Effects of the Invention]

[0013] According to one embodiment of this document, the overall video compression efficiency can be improved.

[0014] According to one embodiment of this document, inter-prediction can be performed efficiently.

[0015] According to one embodiment of this document, unnecessary syntax signaling can be efficiently removed during interpretation.

[0016] According to one embodiment of this document, information regarding the merge mode can be efficiently signaled during inter-prediction.

[0017] According to one embodiment of this document, duplicate syntax can be removed in merged data syntax. [Brief explanation of the drawing]

[0018] [Figure 1] An example of a video / image coding system to which the embodiments described herein can be applied is outlined below. [Figure 2] This diagram schematically illustrates the configuration of a video / image encoding device to which the embodiments described in this document can be applied. [Figure 3] This figure schematically illustrates the configuration of a video / image decoding device to which the embodiments described herein can be applied. [Figure 4] This diagram schematically shows the interpretation prediction unit within the encoding device. [Figure 5] This diagram schematically shows the interpretation prediction unit within the decoding device. [Figure 6] This diagram illustrates spatial candidates that can be used for interpretation. [Figure 7] This diagram illustrates the temporal candidates that can be used for interpretation. [Figure 8] This diagram illustrates a subblock-based temporal motion vector prediction process that can be used during interpretation. [Figure 9]A diagram for explaining a partitioning mode applicable to inter prediction. [Figure 10] An example of a video / video encoding method and related components including an inter prediction method according to an embodiment of this document is schematically shown. [Figure 11] An example of a video / video encoding method and related components including an inter prediction method according to an embodiment of this document is schematically shown. [Figure 12] An example of a video / video decoding method and related components including an inter prediction method according to an embodiment of this document is schematically shown. [Figure 13] An example of a video / video decoding method and related components including an inter prediction method according to an embodiment of this document is schematically shown. [Figure 14] An example of a content streaming system to which the embodiments disclosed in this document can be applied is shown.

Mode for Carrying Out the Invention

[0019] The disclosure of this document can be modified in various ways and can have various embodiments. Therefore, specific embodiments will be illustrated in the drawings and described in detail. The terms used in this document are merely used to describe specific embodiments and are not intended to limit the technical idea of this document. Singular expressions include the expression "at least one" unless the context clearly has a different meaning. Terms such as "including" or "having" in this document are intended to specify the existence of features, numbers, steps, operations, components, parts, or combinations thereof described in the specification, and it should be understood that the existence or addition possibility of one or more other features, numbers, steps, operations, components, parts, or combinations thereof is not precluded in advance.

[0020] On the other hand, each configuration shown in the drawings described in this document is illustrated independently for the convenience of explaining its distinct characteristic functions, and does not mean that each configuration is implemented with separate hardware or separate software. For example, two or more of the configurations may be combined to form a single configuration, and one configuration may be divided into multiple configurations. Embodiments in which each configuration is integrated and / or separated are also included in the scope of disclosure in this document, as long as they do not deviate from the essence of the methods disclosed in this document.

[0021] In this document, the terms " / " and "," should be interpreted as "and / or." For example, "A / B" is interpreted as "A and / or B," and "A, B" is interpreted as "A and / or B." Additionally, "A / B / C" means "at least one of A, B, and / or C." Also, "A, B, C" means "at least one of A, B, and / or C."

[0022] Furthermore, in this document, "or" should be interpreted as "and / or". For example, "A or B" may mean 1) only "A", 2) only "B", or 3) both "A and B". In other words, "or" in this document may mean "additionally or alternatively".

[0023] This document relates to video / image coding. For example, the methods / embodiments disclosed in this document are applicable to the methods disclosed in the VVC (versatile video coding) standard. Furthermore, the methods / embodiments disclosed in this document are applicable to the methods disclosed in the EVC (essential video coding) standard, AV1 (AOMedia Video 1) standard, AVS2 (2nd generation of audio video coding standard), or next-generation video / image coding standards (e.g., H.267, H.268, etc.).

[0024] This document presents various embodiments of video / image coding, and unless otherwise noted, these embodiments may be combined with each other.

[0025] The embodiments described in this document will be explained in more detail below with reference to the attached drawings. Hereafter, the same reference numerals will be used for identical components in the drawings, and redundant descriptions of identical components will be omitted.

[0026] Figure 1 schematically shows an example of a video / image coding system to which the embodiments described in this document can be applied.

[0027] As shown in Figure 1, a video / image coding system may comprise a first device (source device) and a second device (receiving device). The source device can transmit encoded video / image information or data to the receiving device in file or streaming form via a digital storage medium or network.

[0028] The source device may comprise a video source, an encoding device, and a transmitter. The receiving device may comprise a receiver, a decoding device, and a renderer. The encoding device may be called a video / image encoding device, and the decoding device may be called a video / image decoding device. The transmitter may be provided in the encoding device. The receiver may be provided in the decoding device. The renderer may comprise a display unit, which may consist of a separate device or external component.

[0029] A video source can acquire video / images through processes such as video / image capture, synthesis, or generation. A video source may include video / image capture devices and / or video / image generation devices. Video / image capture devices may include, for example, one or more cameras, or video / image archives containing previously captured video / images. Video / image generation devices may include, for example, computers, tablets, and smartphones, and can generate video / images (electronically). For example, virtual video / images may be generated via a computer, in which case the video / image capture process may be replaced by the process of generating the associated data.

[0030] An encoding device can encode input video / image data. For compression and coding efficiency, the encoding device can perform a series of steps, including prediction, transformation, and quantization. The encoded data (encoded video / image information) can be output in bitstream format.

[0031] The transmitting unit can transmit encoded video / image information or data output in bitstream format to the receiving unit of a receiving device via a digital storage medium or network in file or streaming format. The digital storage medium can include various storage media such as USB, SD, CD, DVD, Blu-ray, HDD, SSD, etc. The transmitting unit may include elements for generating media files via a predetermined file format and may include elements for transmission via a broadcast / communication network. The receiving unit can receive / extract the bitstream and transmit it to a decoding device.

[0032] A decoding device can decode video / images by performing a series of steps, such as inverse quantization, inverse transformation, and prediction, corresponding to the operation of an encoding device.

[0033] The renderer can render the decoded video / image. The rendered video / image can be displayed via the display unit.

[0034] In this document, at least one of quantization / inverse quantization and / or transformation / inverse transformation may be omitted. If quantization / inverse quantization is omitted, the quantized transformation coefficients are called transformation coefficients. If transformation / inverse transformation is omitted, the transformation coefficients may be called coefficients or residual coefficients, or for consistency of expression, they may be called transformation coefficients.

[0035] In this document, quantized transformation coefficients and transformation coefficients may also be referred to as transformation coefficients and scaled transformation coefficients, respectively. In this case, residual information includes information about the transformation coefficients, which can be signaled via residual coding syntax. Based on the residual information (or information about the transformation coefficients), the transformation coefficients are derived, and the scaled transformation coefficients are derived by an inverse transformation (scaling) of the transformation coefficients. Based on an inverse transformation (transformation) of the scaled transformation coefficients, the residual samples are derived. This can be similarly applied / expressed in other parts of this document.

[0036] In this document, "video" can mean a collection of images over time. "Picture" generally refers to a unit representing a single image at a specific time point in time, and "slice" or "tile" is a unit that constitutes part of a picture in coding. A slice or tile may contain one or more CTUs (coding tree units). A single picture may consist of one or more slices or tiles. A single picture may consist of one or more tile groups. A tile group may contain one or more tiles. A brick may represent a rectangular region of CTU rows within a tile in a picture. A tile may be partitioned into multiple bricks, each of which consists of one or more CTU rows within the tile. A tile that is not partitioned into multiple bricks may also be referred to as a brick.A brick scan is a specific sequential ordering of CTUs partitioning a picture in which the CTUs are ordered consecutively in CTU raster scan in a brick, bricks within a tile are ordered consecutively in a raster scan of the bricks of the tile, and tiles in a picture are ordered consecutively in a raster scan of the tiles of the picture. A tile is a rectangular region of CTUs within a particular tile column and a particular tile row in a picture. The tile column is a rectangular region of CTUs having a height equal to the height of the picture and a width specified by syntax elements in the picture parameter set.The tile row is a rectangular region of CTUs having a height specified by syntax elements in the picture parameter set and a width equal to the width of the picture. A tile scan is a specific sequential ordering of CTUs partitioning a picture in which the CTUs are ordered consecutively in CTU raster scan in a tile whereas tiles in a picture are ordered consecutively in a raster scan of the tiles of the picture. A slice includes an integer number of bricks of a picture that may be exclusively contained in a single NAL unit. A slice may consist of either a number of complete tiles or only a consecutive sequence of complete bricks of one tile. In this document, the terms tile group and slice may be used interchangeably.For example, in this document, tile group / tile group header may also be called slice / slice header.

[0037] A pixel or pel can refer to the smallest unit that makes up a picture (or image). Alternatively, the term "sample" can be used as a counterpart to pixel. A sample can generally represent a pixel or a pixel value, and may represent only the luma component pixel / pixel value, or only the chroma component pixel / pixel value.

[0038] A unit represents a basic unit of image processing. A unit includes at least one of a specific region of a picture and information associated with that region. A unit may include one luma block and two chroma (e.g., cb, cr) blocks. The term unit may be used interchangeably with terms such as block or area. Generally, an M×N block may include a sample (or sample array) consisting of M columns and N rows, or a set (or array) of transform coefficients.

[0039] Figure 2 is a schematic diagram illustrating the configuration of a video / image encoding device to which the embodiments described in this document can be applied. Hereinafter, "video encoding device" includes image encoding devices.

[0040] As shown in Figure 2, the encoding device 200 can be configured to include an image partitioner 210, a predictor 220, a residual processor 230, an entropy encoder 240, an adder 250, a filter 260, and a memory 270. The predictor 220 may include an inter-predictor 221 and an intra-predictor 222. The residual processor 230 may include a transformer 232, a quantizer 233, a dequantizer 234, and an inverse transformer 235. The residual processor 230 may further include a subtractor 231. The adder 250 may be called a reconstructor or a reconstructed block generator. The aforementioned video splitting unit 210, prediction unit 220, residual processing unit 230, entropy encoding unit 240, addition unit 250, and filtering unit 260 can be configured by one or more hardware components (e.g., an encoder chipset or processor) depending on the embodiment. The memory 270 may also include a DPB (decoded picture buffer) and may be configured by a digital storage medium. The hardware components may further include the memory 270 as an internal / external component.

[0041] The video splitting unit 210 can split the input video (or picture, frame) input to the encoding device 200 into one or more processing units. For example, the processing units may be called coding units (CUs). In this case, the coding units can be recursively split from a coding tree unit (CTU) or the largest coding unit (LCU) by a QTBTTT (Quad-tree binary-tree ternary-tree) structure. For example, one coding unit can be split into multiple coding units of deeper depth based on a quad-tree structure, a binary-tree structure, and / or a ternary structure. In this case, for example, the quad-tree structure may be applied first, followed by the binary-tree structure and / or the ternary structure. Alternatively, the binary-tree structure may be applied first. The coding procedure according to this disclosure may be performed based on the final coding unit that is not further split. In this case, based on coding efficiency due to video characteristics, the largest coding unit can be used as the final coding unit, or, if necessary, the coding unit can be recursively divided into lower-depth coding units so that the optimally sized coding unit is used as the final coding unit. Here, the coding procedure may include procedures such as prediction, transformation, and restoration, which will be described later. As another example, the processing unit may further comprise a prediction unit (PU) or a transformation unit (TU). In this case, the prediction unit and the transformation unit can each be separated or partitioned from the final coding unit described above.The prediction unit may be a unit of sample prediction, and the conversion unit may be a unit for deriving conversion coefficients and / or a unit for deriving a residual signal from conversion coefficients.

[0042] The term "unit" can sometimes be used interchangeably with terms such as "block" or "area." Generally, an M×N block can represent a set of samples or transform coefficients consisting of M columns and N rows. A sample can generally represent a pixel or a pixel value, and may represent only the luminance (luma) component pixel / pixel value, or only the chroma component pixel / pixel value. A sample can be used as the term corresponding to a single picture (or image) pixel or pel.

[0043] The encoding device 200 can generate a residual signal (residual block, residual sample array) by subtracting the predicted signal (predicted block, predicted sample array) output from the inter-prediction unit 221 or intra-prediction unit 222 from the input video signal (original block, original sample array), and the generated residual signal is transmitted to the conversion unit 232. In this case, as shown in the figure, the unit that subtracts the predicted signal (predicted block, predicted sample array) from the input video signal (original block, original sample array) within the encoder 200 can be called the subtraction unit 231. The prediction unit can make predictions for the block to be processed (hereinafter referred to as the current block) and generate a predicted block that includes predicted samples for the current block. The prediction unit can determine whether intra-prediction or inter-prediction is applied on a current block or CU basis. The prediction unit can generate various information related to prediction, such as prediction mode information, and transmit it to the entropy encoding unit 240, as will be described later in the explanation of each prediction mode. Prediction information can be encoded by the entropy encoding unit 240 and output in bitstream format.

[0044] The intra-prediction unit 222 can predict the current block by referring to a sample in the current picture. The referenced sample can be located in the vicinity (neighbor) of the current block or at a distance, depending on the prediction mode. The prediction mode in intra-prediction can include multiple non-directional modes and multiple directional modes. Non-directional modes can include, for example, DC mode and planar mode. Directional modes can include, for example, 33 directional prediction modes or 65 directional prediction modes, depending on the degree of fineness of the prediction direction. However, this is illustrative, and more or fewer directional prediction modes may be used depending on the settings. The intra-prediction unit 222 can also determine the prediction mode to apply to the current block using the prediction modes applied to the surrounding blocks.

[0045] The interprediction unit 221 can derive a predicted block relative to the current block based on a reference block (reference sample array) identified by motion vectors on the reference picture. In this case, in order to reduce the amount of motion information transmitted in interprediction mode, motion information can be predicted in units of blocks, subblocks, or samples based on the correlation of motion information between the surrounding block and the current block. The motion information may include motion vectors and reference picture indices. The motion information may further include interprediction direction information (L0 prediction, L1 prediction, Bi prediction, etc.). In the case of interprediction, surrounding blocks may include spatial neighboring blocks present in the current picture and temporal neighboring blocks present in the reference picture. The reference picture containing the reference block and the reference picture containing the temporal neighboring block may be the same or different. The temporal neighboring block may be called a collocated reference block, col CU, etc., and the reference picture containing the temporal neighboring block may be called a collocated picture (colPic). For example, the interpretation unit 221 can construct a motion information candidate list based on surrounding blocks and generate information indicating which candidate is used to derive the motion vector and / or reference picture index of the current block. Interpretation can be performed based on various prediction modes; for example, in skip mode and merge mode, the interpretation unit 221 can use the motion information of surrounding blocks as the motion information of the current block. In skip mode, unlike merge mode, a residual signal may not be transmitted.In motion vector prediction (MVP) mode, the motion vector of the surrounding blocks is used as a motion vector predictor, and the motion vector difference is signaled to indicate the motion vector of the current block.

[0046] The prediction unit 220 can generate prediction signals based on various prediction methods described later. For example, the prediction unit can apply intra-prediction or inter-prediction for predictions on a single block, and can also apply intra-prediction and inter-prediction simultaneously. This can be called combined inter and intra prediction (CIIP). The prediction unit can also base its predictions on an intra-block copy (IBC) prediction mode or a palette mode for predictions on a block. The IBC prediction mode or palette mode can be used for content video / video coding such as in games, for example, in SCC (screen content coding). IBC basically performs predictions within the current picture, but can be performed similarly to inter-prediction in that it derives reference blocks within the current picture. That is, IBC can use at least one of the inter-prediction techniques described in this document. Palette mode can be considered an example of intra-coding or intra-prediction. When palette mode is applied, sample values ​​within the picture can be signaled based on information about the palette table and palette index.

[0047] The prediction signal generated via the prediction unit (including the inter-prediction unit 221 and / or the intra-prediction unit 222) can be used to generate a restored signal or to generate a residual signal.

[0048] The transformation unit 232 can apply transformation techniques to the residual signal to generate transformation coefficients. For example, the transformation technique may include at least one of DCT (Discrete Cosine Transform), DST (Discrete Sine Transform), GBT (Graph-Based Transform), or CNT (Conditionally Non-linear Transform). Here, GBT refers to a transformation obtained from a graph when relational information between pixels is represented by this graph. CNT refers to a transformation obtained by generating a prediction signal using all previously reconstructed pixels. Furthermore, the transformation process may be applied to pixel blocks of the same size and square shape, or to non-square blocks of variable size.

[0049] The quantization unit 233 quantizes the conversion coefficients and transmits them to the entropy encoding unit 240, which can encode the quantized signal (information about the quantized conversion coefficients) and output it as a bitstream. The information about the quantized conversion coefficients can be called residual information. The quantization unit 233 can rearrange the block-shaped quantized conversion coefficients into a one-dimensional vector form based on the coefficient scan order, and can also generate information about the quantized conversion coefficients based on the one-dimensional vector form of the quantized conversion coefficients.

[0050] The entropy encoding unit 240 can perform various encoding methods, such as exponential Golomb, CAVLC (context-adaptive variable length coding), and CABAC (context-adaptive binary arithmetic coding). In addition to the quantized conversion coefficients, the entropy encoding unit 240 can also encode information necessary for video / image reconstruction (e.g., values ​​of syntax elements) together with or separately. The encoded information (e.g., encoded video / image information) can be transmitted or stored in bitstream form in units of NAL (network abstraction layer) units. The video / image information may further include information about various parameter sets, such as the adaptation parameter set (APS), picture parameter set (PPS), sequence parameter set (SPS), or video parameter set (VPS). The video / image information may also further include general constraint information. In this document, information and / or syntax elements transmitted / signaled from an encoding device to a decoding device may be included in video / image information. The video / image information may be encoded via the encoding procedure described above and included in the bitstream. The bitstream may be transmitted over a network or stored in a digital storage medium. Here, the network may include broadcast networks and / or communication networks, and the digital storage medium may include various storage media such as USB, SD, CD, DVD, Blu-ray, HDD, SSD, etc.The signal output from the entropy encoding unit 240 can be transmitted by a transmitting unit (not shown) and / or stored by a storage unit (not shown) which can be configured as internal / external elements of the encoding device 200, or the transmitting unit may be included in the entropy encoding unit 240.

[0051] The quantized conversion coefficients output from the quantization unit 233 can be used to generate a prediction signal. For example, a residual signal (residual block or residual sample) can be reconstructed by applying inverse quantization and inverse transformation to the quantized conversion coefficients via the inverse quantization unit 234 and the inverse transformation unit 235. The adder 155 can generate a reconstructed signal (reconstructed picture, reconstructed block, reconstructed sample array) by adding the reconstructed residual signal to the prediction signal output from the inter-prediction unit 221 or the intra-prediction unit 222. If there is no residual for the block to be processed, such as when skip mode is applied, the predicted block can be used as the reconstructed block. The adder 250 can be called the reconstruction unit or reconstructed block generation unit. The generated reconstructed signal can be used for intra-prediction of the next block to be processed in the current picture, or, as described later, for inter-prediction of the next picture after filtering.

[0052] On the other hand, LMCS (luma mapping with chroma scaling) can also be applied during the picture encoding and / or restoration process.

[0053] The filtering unit 260 can improve subjective / objective image quality by applying filtering to the restored signal. For example, the filtering unit 260 can apply various filtering methods to the restored picture to generate a modified restored picture, and store the modified restored picture in the memory 270, specifically in the DPB of the memory 270. The various filtering methods can include, for example, deblocking filtering, sample adaptive offset, adaptive loop filter, and bilateral filter. The filtering unit 260 can generate various filtering-related information and transmit it to the entropy encoding unit 240, as will be described later in the explanation of each filtering method. The filtering-related information can be encoded by the entropy encoding unit 240 and output in bitstream format.

[0054] The corrected restored picture sent to memory 270 can be used as a reference picture in the interpretation unit 221. When interpretation is applied via this, the encoding device can avoid prediction mismatches between the encoding device 100 and the decoding device, and can also improve encoding efficiency.

[0055] The DPB in memory 270 can store the corrected restored picture for use as a reference picture in the inter-prediction unit 221. Memory 270 can store motion information of blocks from which motion information in the current picture has been derived (or encoded) and / or motion information of blocks in the picture that have already been restored. The stored motion information can be transmitted to the inter-prediction unit 221 for use as motion information of spatially surrounding blocks or motion information of temporally surrounding blocks. Memory 270 can store restored samples of restored blocks in the current picture and transmit them to the intra-prediction unit 222.

[0056] Figure 3 is a schematic diagram illustrating the configuration of a video / image decoding device to which the embodiments described in this document can be applied.

[0057] As shown in Figure 3, the decoding device 300 can be configured to include an entropy decoder 310, a residual processor 320, a predictor 330, an adder 340, a filter 350, and a memory 360. The predictor 330 may include an inter-prediction unit 331 and an intra-prediction unit 332. The residual processor 320 may include a dequantizer 321 and an inverse transformer 321. The aforementioned entropy decoder 310, residual processor 320, predictor 330, adder 340, and filtering unit 350 can be configured by a single hardware component (e.g., a decoder chipset or processor) depending on the embodiment. The memory 360 may include a decoded picture buffer (DPB) and may be configured by a digital storage medium. The aforementioned hardware component may also further include memory 360 as an internal / external component.

[0058] When a bitstream containing video / image information is input, the decoding device 300 can reconstruct the image in accordance with the process by which the video / image information was processed in the encoding device shown in Figure 3. For example, the decoding device 300 can derive units / blocks based on block division-related information obtained from the bitstream. The decoding device 300 can perform decoding using the processing units applied in the encoding device. Therefore, the decoding processing unit can be, for example, a coding unit, which can be divided from a coding tree unit or a maximum coding unit according to a quad-tree structure, a binary tree structure, and / or a terminally tree structure. One or more conversion units can be derived from the coding unit. The reconstructed video signal decoded and output via the decoding device 300 can then be played back via a playback device.

[0059] The decoding device 300 can receive the signal output from the encoding device shown in Figure 3 in bitstream form, and the received signal can be decoded via the entropy decoding unit 310. For example, the entropy decoding unit 310 can parse the bitstream to derive information necessary for video restoration (or picture restoration) (e.g., video / image information). The video / image information may further include information about various parameter sets, such as the adaptation parameter set (APS), picture parameter set (PPS), sequence parameter set (SPS), or video parameter set (VPS). The video / image information may also further include general constraint information. The decoding device can further decode the picture based on the parameter set information and / or the general constraint information. The signaling / received information and / or syntax elements described later in this document can be decoded via the decoding procedure and obtained from the bitstream. For example, the entropy decoding unit 310 can decode information in the bitstream based on a coding method such as exponential Golomb coding, CAVLC, or CABAC, and output the values ​​of syntax elements necessary for image restoration and the quantized values ​​of conversion coefficients related to the resistivity. More specifically, the CABAC entropy decoding method receives bins corresponding to each syntax element in the bitstream, determines a context model using the syntax element information to be decoded and the decoding information of the surrounding and decoded blocks or the symbol / bin information decoded in a previous step, predicts the probability of bin occurrence based on the determined context model, performs arithmetic decoding of the bins, and generates symbols corresponding to the values ​​of each syntax element.At this time, the CABAC entropy decoding method can update the context model after determining the context model by utilizing the decoded symbol / bin information for the context model of the next symbol / bin. Of the information decoded by the entropy decoding unit 310, the information related to prediction is provided to the prediction unit (inter-prediction unit 332 and intra-prediction unit 331), and the residual values ​​that have been entropy decoded by the entropy decoding unit 310, i.e., the quantized conversion coefficients and related parameter information, can be input to the residual processing unit 320.

[0060] The residual processing unit 320 can derive residual signals (residual blocks, residual samples, residual sample arrays). Furthermore, information related to filtering from the information decoded by the entropy decoding unit 310 can be provided to the filtering unit 350. Meanwhile, a receiving unit (not shown) that receives signals output from the encoding device can be further configured as an internal / external element of the decoding device 300, or the receiving unit can be a component of the entropy decoding unit 310. On the other hand, the decoding device relating to this document may be called a video / image / picture decoding device, and the decoding device can also be divided into an information decoder (video / image / picture information decoder) and a sample decoder (video / image / picture sample decoder). The information decoder may include the entropy decoding unit 310, and the sample decoder may include at least one of the inverse quantization unit 321, inverse transformation unit 322, addition unit 340, filtering unit 350, memory 360, inter-prediction unit 332, and intra-prediction unit 331.

[0061] The inverse quantization unit 321 can inverse quantize the quantized transformation coefficients and output the transformation coefficients. The inverse quantization unit 321 can rearrange the quantized transformation coefficients in a two-dimensional block form. In this case, the rearrangement can be performed based on the coefficient scan order performed by the encoding device. The inverse quantization unit 321 can perform inverse quantization on the quantized transformation coefficients using quantization parameters (e.g., quantization step size information) and obtain the transformation coefficients.

[0062] In the inverse conversion unit 322, the conversion coefficients are inversely converted to obtain a residual signal (residual block, residual sample array).

[0063] The prediction unit 330 can make predictions for the current block and generate a predicted block containing prediction samples for the current block. Based on the prediction information output from the entropy decoding unit 310, the prediction unit 330 can determine whether intra-prediction or inter-prediction is applied to the current block, and can determine a specific intra / inter-prediction mode.

[0064] The prediction unit 330 can generate prediction signals based on various prediction methods described later. For example, the prediction unit can apply intra-prediction or inter-prediction for prediction of a single block, and can also apply intra-prediction and inter-prediction simultaneously. This can be called combined inter and intra prediction (CIIP). The prediction unit can also base its prediction on an intra-block copy (IBC) prediction mode or on a palette mode for prediction of a block. The IBC prediction mode or palette mode can be used for content video / movie coding such as games, for example, as in SCC (screen content coding). IBC basically performs prediction within the current picture, but can be performed similarly to inter-prediction in that it derives a reference block within the current picture. That is, IBC can utilize at least one of the inter-prediction techniques described in this document. Palette mode can be considered an example of intra-coding or intra-prediction. When palette mode is applied, information about the palette table and palette index can be included in the video / movie information and signaled.

[0065] The intra-prediction unit 331 can predict the current block by referring to a sample in the current picture. The referenced sample can be located in the vicinity (neighbor) of the current block or at a distance from it, depending on the prediction mode. In intra-prediction, the prediction mode can include multiple non-directional modes and multiple directional modes. The intra-prediction unit 331 can also determine the prediction mode to be applied to the current block using the prediction modes applied to the surrounding blocks.

[0066] The interprediction unit 332 can derive a predicted block for the current block based on a reference block (reference sample array) identified by motion vectors on the reference picture. In this case, in order to reduce the amount of motion information transmitted in interprediction mode, motion information can be predicted in blocks, subblocks, or samples based on the correlation of motion information between neighboring blocks and the current block. The motion information may include motion vectors and reference picture indices. The motion information may further include interprediction direction information (L0 prediction, L1 prediction, Bi prediction, etc.). In the case of interprediction, neighboring blocks may include spatial neighboring blocks that exist in the current picture and temporal neighboring blocks that exist in the reference picture. For example, the interprediction unit 332 can construct a motion information candidate list based on neighboring blocks and derive the motion vector and / or reference picture index of the current block based on the received candidate selection information. Interprediction can be performed based on various prediction modes, and the prediction information may include information indicating the mode of interprediction for the current block.

[0067] The adder 340 can generate a restored signal (restored picture, restored block, restored sample array) by adding the acquired residual signal to the predicted signal (predicted block, predicted sample array) output from the prediction unit (which comprises an inter-prediction unit 332 and / or an intra-prediction unit 331). If there is no residual for the block to be processed, such as when skip mode is applied, the predicted block can be used as the restored block.

[0068] The summing unit 340 may be called the restoration unit or restoration block generation unit. The generated restoration signal can be used for intra-prediction of the next block to be processed in the current picture, and can be output after filtering as described later, or it can be used for intra-prediction of the next picture.

[0069] On the other hand, LMCS (luma mapping with chroma scaling) can also be applied during the picture decoding process.

[0070] The filtering unit 350 can apply filtering to the restored signal to improve subjective / objective image quality. For example, the filtering unit 350 can apply various filtering methods to the restored picture to generate a modified restored picture, and can transmit the modified restored picture to the memory 360, specifically to the DPB of the memory 360. The various filtering methods may include, for example, deblocking filtering, sample adaptive offset, adaptive loop filter, and bilateral filter.

[0071] The (modified) restored picture stored in the DPB of memory 360 can be used as a reference picture by the inter-prediction unit 332. Memory 360 can store motion information of blocks from which motion information in the current picture has been derived (or decoded) and / or motion information of blocks in the picture that have already been restored. The stored motion information can be transmitted to the inter-prediction unit 260 for use as motion information of spatially surrounding blocks or motion information of temporally surrounding blocks. Memory 360 can store restored samples of restored blocks in the current picture and transmit them to the intra-prediction unit 331.

[0072] In this specification, the embodiments described for the filtering unit 260, inter-prediction unit 221, and intra-prediction unit 222 of the encoding device 200 can be applied identically or in a corresponding manner to the filtering unit 350, inter-prediction unit 332, and intra-prediction unit 331 of the decoding device 300, respectively.

[0073] The video / image coding method described in this document is based on the following partitioning structure. Specifically, procedures such as prediction, residual processing (inverse transformation, inverse quantization, etc.), syntax element coding, and filtering, described later, can be performed based on the CTU, CU (and / or TU, PU) derived from the partitioning structure. The block partitioning procedure is performed in the video division unit 210 of the encoding device, and the partitioning-related information is processed (encoded) in the entropy encoding unit 240 and transmitted to the decoding device in bitstream form. The entropy decoding unit 310 of the decoding device derives the block partitioning structure of the current picture based on the partitioning-related information obtained from the bitstream, and can perform a series of procedures for video decoding (e.g., prediction, residual processing, block / picture restoration, in-loop filtering, etc.) based on this. The CU size and TU size may be the same, or there may be multiple TUs within the CU area. On the other hand, the CU size generally refers to the size of the luma component (sample) CB (coding block). The TU size generally refers to the luminous component (sample) TB (transform block) size. The chroma component (sample) CB or TB size can be derived based on the luminous component (sample) CB or TB size, depending on the component ratio of the picture / video color format (chroma format, e.g., 4:4:4, 4:2:2, 4:2:0, etc.). The TU size is derived based on maxTbSize. For example, if the CU size is larger than the maxTbSize, multiple TUs (TBs) of the maxTbSize can be derived from the CU, and transformation / inverse transformation can be performed in units of the TU (TB). Also, for example, when intra-prediction is applied, the intra-prediction mode / type is derived in units of the CU (or CB), and the peripheral reference sample derivation and prediction sample generation procedures can be performed in units of TU (or TB).In this case, one or more TUs (or TBs) exist within a single CU (or CB) region, and in this case, the multiple TUs (or TBs) can share the same intra-prediction mode / type.

[0074] Furthermore, in the video / image coding described in this document, the image processing units have a hierarchical structure. A single picture is divided into one or more tiles, bricks, slices, and / or tile groups. A single slice contains one or more bricks. A single brick contains one or more CTU rows within a tile. A slice contains an integer number of bricks in a picture. A single tile group contains one or more tiles. A single tile contains one or more CTUs. The CTU can be divided into one or more CUs. A tile is a rectangular region of CTUs within a particular tile column and a particular tile row in a picture. A tile group contains an integer number of tiles obtained by scanning the tiles in the picture. A slice header can carry information / parameters applicable to the slice (blocks within the slice). If the encoding / decoding device has a multicore processor, the encoding / decoding procedures for the tiles, slices, bricks, and / or tile groups are processed in parallel. In this document, slices and tile groups may be used interchangeably. That is, a tile group header may be called a slice header. Here, a slice has one of the following slice types: intra(I)slice, predictive(P)slice, and bI-predictive(B)slice. For blocks in an I slice, only intra prediction is used for prediction; inter-prediction is not used. Of course, even in this case, it is possible to code and signal the original sample values ​​without prediction. For blocks in a P slice, intra-prediction or inter-prediction is used, and if inter-prediction is used, only uni prediction is used. On the other hand, for blocks in a B slice, intra-prediction or inter-prediction is used, and if inter-prediction is used, up to bi-prediction may be used.

[0075] In an encoder, the tile / tile group, brick, slice, and maximum and minimum coding unit sizes are determined according to the characteristics of the video image (e.g., resolution) or considering coding efficiency or parallel processing, and information related to this or information that can guide these determinations is included in the bitstream.

[0076] The decoder can obtain information indicating whether the picture's tiles / tile groups, bricks, slices, and CTUs within a tile are divided into multiple coding units. Efficiency can be improved by ensuring that such information is only obtained (transmitted) under specific conditions.

[0077] The slice header (slice header syntax) includes information / parameters that can be applied in common to the slice. The APS (APS syntax) or PPS (PPS syntax) includes information / parameters that can be applied in common to one or more pictures. The SPS (SPS syntax) includes information / parameters that can be applied in common to one or more sequences. The VPS (VPS syntax) includes information / parameters that can be applied in common to multiple layers. The DPS (DPS syntax) includes information / parameters that can be applied in common to video in general. The DPS includes information / parameters related to the concatenation of the CVS (coded video sequence).

[0078] In this document, higher-level syntax includes at least one of the APS syntax, PPS syntax, SPS syntax, VPS syntax, DPS syntax, and slice header syntax.

[0079] Furthermore, information regarding the division and configuration of tiles / tile groups / bricks / slices, for example, is configured in the encoding stage via the higher-level syntax and transmitted to the decoding device in bitstream form.

[0080] In video coding, the pictures that make up the video are encoded / decoded according to a series of decoding orders. The picture order, which corresponds to the output order of the decoded pictures, may be set differently from the decoding order, and based on this, not only forward prediction but also reverse prediction can be performed during interpretation.

[0081] The picture decoding procedure generally includes a procedure for acquiring image / video information from a bitstream (by decoding), a picture restoration procedure, and an in-loop filtering procedure for the restored picture. The picture restoration procedure is performed based on predicted samples and residual samples obtained through the inter / intra prediction and residual processing (inverse quantization and inverse transformation of quantized transformation coefficients) processes described in this document. A modified restored picture is generated by the in-loop filtering procedure on the restored picture generated by the picture restoration procedure, and the modified restored picture is output as a decoded picture and can be stored in the decoding picture buffer or memory 360 of the decoding device and used as a reference picture in the inter-prediction procedure when decoding the picture. In some cases, the in-loop filtering procedure may be omitted, in which case the restored picture is output as a decoded picture and can be stored in the decoding picture buffer or memory 360 of the decoding device and used as a reference picture in the inter-prediction procedure when decoding the picture. The in-loop filtering procedure includes, as described above, a deblocking filtering procedure, a sample adaptive offset (SAO) procedure, an adaptive loop filter (ALF) procedure, and / or a bi-lateral filter procedure, and some or all of these may be omitted. Furthermore, one or part of the deblocking filtering procedure, the SAO procedure, the ALF procedure, and the bi-lateral filter procedure may be applied sequentially, or all of them may be applied sequentially. For example, the SAO procedure may be performed after the deblocking filtering procedure is applied to the restored picture. Alternatively, for example, the ALF procedure may be performed after the deblocking filtering procedure is applied to the restored picture. This is also done in the encoding device.

[0082] The picture encoding procedure may include not only a procedure for encoding information for picture reconstruction (e.g., prediction information, residual information, partitioning information, etc.) and outputting it in bitstream form, but also a procedure for generating a reconstruction picture for the current picture and a procedure for applying in-loop filtering to the reconstruction picture (optional). The encoding device can derive (corrected) residual samples from the quantized conversion coefficients via the inverse quantization unit 234 and the inverse conversion unit 235, and can generate a reconstruction picture based on the prediction samples and the (corrected) residual samples. The reconstruction picture thus generated may be identical to the reconstruction picture generated in the decoding device described above. A corrected reconstruction picture is generated via an in-loop filtering procedure on the reconstruction picture, which can be stored in the decoded picture buffer or memory 270, and, as in the case of the decoding device, can be used as a reference picture in the inter-prediction procedure when encoding pictures thereafter. As described above, in some cases, some or all of the loop filtering procedure may be omitted. When the enloop filtering procedure is performed, the (inloop) filtering-related information (parameters) can be encoded in the entropy encoding unit 240 and output in bitstream format, and the decoding device can perform the enloop filtering procedure in the same way as the encoding device based on the filtering-related information.

[0083] This in-loop filtering procedure can reduce noise that occurs during video coding, such as blocking artifacts and ringing artifacts, thereby improving subjective and objective visual quality. Furthermore, by performing the in-loop filtering procedure in both the encoding and decoding devices, the encoding and decoding devices can derive the same prediction results, increasing the reliability of picture coding and reducing the amount of data that needs to be transmitted for picture coding.

[0084] As mentioned above, picture restoration procedures can be performed not only in the decoding device but also in the encoding device. A restored block can be generated based on intra-prediction / inter-prediction for each block, and a restored picture containing the restored block can be generated. If the current picture / slice / tile group is an I picture / slice / tile group, the blocks included in the current picture / slice / tile group can be restored based only on intra-prediction. On the other hand, if the current picture / slice / tile group is a P or B picture / slice / tile group, the blocks included in the current picture / slice / tile group can be restored based on intra-prediction or inter-prediction. In this case, inter-prediction may be applied to some blocks in the current picture / slice / tile group, and intra-prediction may be applied to the remaining blocks. The color components of a picture may include luminous and chroma components, and unless explicitly limited in this document, the methods and embodiments proposed in this document can be applied to luminous and chroma components.

[0085] On the other hand, as mentioned above, predictions are made to improve compression efficiency when performing video coding. This makes it possible to generate a predicted block that includes predicted samples for the current block, which is the block to be coded. Here, the predicted block includes predicted samples in the spatial domain (or pixel domain). The predicted block is similarly derived in the encoding device and the decoding device, and the encoding device can improve video coding efficiency by signaling the decoding device not the original sample values ​​of the original block themselves, but information about the residual between the original block and the predicted block (residual information). The decoding device can derive a residual block that includes residual samples based on the residual information, combine the residual block and the predicted block to generate a restored block that includes restored samples, and generate a restored picture that includes the restored block.

[0086] The residual information is generated by a transformation and quantization procedure. For example, the encoding device derives a residual block between the original block and the predicted block, performs a transformation procedure on the residual samples (residual sample array) contained in the residual block to derive transformation coefficients, performs a quantization procedure on the transformation coefficients to derive quantized transformation coefficients, and signals the relevant residual information to the decoding device (via a bitstream). Here, the residual information may include information such as the value information, position information, transformation technique, transformation kernel, and quantization parameters of the quantized transformation coefficients. The decoding device can perform an inverse quantization / inverse transformation procedure based on the residual information to derive a residual sample (or residual block). The decoding device generates a reconstructed picture based on the predicted block and the residual block. The encoding device also subsequently inverse quantization / inverse transformation of the quantized transformation coefficients for reference for interpretation of the picture to derive a residual block, and generates a reconstructed picture based on this.

[0087] When inter-prediction is applied to the current block, the prediction unit of the encoding / decoding device performs inter-prediction on a block-by-block basis to derive predicted samples. Inter-prediction is a prediction derived in a manner that is dependent on data elements (e.g., sample values ​​or motion information) of picture(s) other than the current picture. When inter-prediction is applied to the current block, a predicted block (predicted sample array) for the current block can be derived based on a reference block (reference sample array) identified by motion vectors on the reference picture indicated by the reference picture index. At this time, in order to reduce the amount of motion information transmitted in inter-prediction mode, the motion information of the current block can be predicted on a block, sub-block, or sample basis based on the correlation of motion information between surrounding blocks and the current block. The motion information may include motion vectors and reference picture indexes. The motion information may further include inter-prediction type information (L0 prediction, L1 prediction, Bi prediction, etc.). When interpretation is applied, the surrounding block includes a spatial neighboring block currently present in the picture and a temporal neighboring block present in the reference picture. The reference picture containing the reference block and the reference picture containing the temporal neighboring block may be the same or different. The temporal neighboring block may be called a collocated reference block or colCU, and the reference picture containing the temporal neighboring block may be called a collocated picture (colPic).For example, a list of motion information candidates may be constructed based on the surrounding blocks of the current block, and a flag or index information may be signaled indicating which candidate is selected (used) to derive the motion vector and / or reference picture index of the current block. Interpretation can be performed based on various prediction modes; for example, in skip mode and (normal) merge mode, the motion information of the current block may be identical to the motion information of the selected surrounding blocks. In skip mode, unlike merge mode, a residual signal may not be transmitted. In motion vector prediction (MVP) mode, the motion vector of the selected surrounding block is used as a motion vector predictor, and the motion vector difference is signaled. In this case, the motion vector of the current block can be derived using the sum of the motion vector predictor and the motion vector difference.

[0088] Interpretation-based video / image encoding procedures can, in general, include, for example, the following:

[0089] Figure 4 is a schematic diagram showing the interpretation prediction unit within the encoding device.

[0090] As shown in Figure 4, the encoding device performs interpretation for the current block. The encoding device derives the interpretation mode and motion information of the current block and generates a prediction sample for the current block. Here, the interpretation mode determination, motion information derivation, and prediction sample generation procedures may be performed simultaneously, or one procedure may be performed before the others. For example, the interpretation unit 221 of the encoding device includes a prediction mode determination unit 221_1, a motion information derivation unit 221_2, and a prediction sample derivation unit 221_3. The prediction mode determination unit 221_1 determines the prediction mode for the current block, the motion information derivation unit 221_2 derives the motion information of the current block, and the prediction sample derivation unit 221_3 derives a prediction sample for the current block. For example, the interpretation unit 221 of the encoding device searches for blocks similar to the current block within a certain area (search area) of the reference picture by motion estimation and derives a reference block whose difference from the current block is the minimum or below a certain standard. Based on this, a reference picture index pointing to the reference picture in which the reference block is located is derived, and a motion vector is derived based on the positional difference between the reference block and the current block. The encoding device determines which of the various prediction modes is to be applied to the current block. The encoding device compares the rate-distortion (RD) costs for the various prediction modes and determines the optimal prediction mode for the current block.

[0091] For example, when skip mode or merge mode is applied to the current block, the encoding device can configure a merge candidate list, as described later, and derive a reference block from among the reference blocks indicated by the merge candidates included in the merge candidate list whose difference from the current block is the smallest or below a certain standard. In this case, a merge candidate related to the derived reference block is selected, and merge index information indicating the selected merge candidate is generated and signaled to the decoding device. The movement information of the current block can be derived using the movement information of the selected merge candidate.

[0092] As another example, when the (A)MVP mode is applied to the current block, the encoding device can configure the (A)MVP candidate list described later, and use the motion vector of the selected mvp candidate from among the mvp (motion vector predictor) candidates included in the (A)MVP candidate list as the mvp of the current block. In this case, for example, the motion vector indicating the reference block derived by the motion estimation described above can be used as the motion vector of the current block, and the mvp candidate having the motion vector with the smallest difference from the motion vector of the current block can become the selected mvp candidate. The MVD (motion vector difference), which is the difference obtained by subtracting the mvp from the motion vector of the current block, can be derived. In this case, information regarding the MVD is signaled to the decoding device. Also, when the (A)MVP mode is applied, the value of the reference picture index can be composed of reference picture index information and separately signaled to the decoding device.

[0093] The encoding device derives a residual sample based on the predicted sample. The encoding device derives the residual sample by comparing the original sample of the current block with the predicted sample.

[0094] The encoding device encodes video information including prediction information and residual information. The encoding device outputs the encoded video information in bitstream format. The prediction information is information related to the prediction procedure and includes prediction mode information (e.g., skip flag, merge flag, or mode index) and motion information. The motion information includes candidate selection information (e.g., merge index, mvp flag, or mvp index) which is information for deriving a motion vector. The motion information also includes the aforementioned MVD information and / or reference picture index information. The motion information also includes information indicating whether L0 prediction, L1 prediction, or bi prediction is applied. The residual information is information about the residual sample. The residual information includes information about the quantized conversion coefficients for the residual sample.

[0095] The output bitstream is stored in a (digital) storage medium and transmitted to a decoding device, or transmitted to a decoding device via a network.

[0096] On the other hand, as mentioned above, the encoding device can generate a reconstructed picture (including a reconstructed sample and a reconstructed block) based on the reference sample and the residual sample. This is because the encoding device can derive the same prediction results as those performed by the decoding device, thereby improving coding efficiency. Therefore, the encoding device stores the reconstructed picture (or reconstructed sample, reconstructed block) in memory and uses it as a reference picture for interpretation. As mentioned above, in-loop filtering procedures and the like can be further applied to the reconstructed picture.

[0097] The video / image decoding procedure based on interpretation broadly includes, for example, the following:

[0098] Figure 5 is a schematic diagram showing the interpretation prediction unit within the decoding device.

[0099] As shown in Figure 5, the decoding device performs operations corresponding to those performed by the encoding device. Based on the received prediction information, the decoding device makes a prediction for the current block and derives a prediction sample.

[0100] Specifically, the decoding device can determine the prediction mode for the current block based on the received prediction information. The decoding device can determine which interprediction mode is applied to the current block based on the prediction mode information within the prediction information.

[0101] For example, based on the merge flag, it can be determined whether the merge mode is applied to the current block or whether the (A)MVP mode is determined. Alternatively, one of several inter-prediction mode candidates can be selected based on the mode index. The inter-prediction mode candidates include skip mode, merge mode and / or (A)MVP mode, or include various inter-prediction modes as described below.

[0102] The decoding device derives motion information for the current block based on the determined inter prediction mode. For example, if a skip mode or merge mode is applied to the current block, the decoding device configures a merge candidate list, as described later, and selects one of the merge candidates included in the merge candidate list. This selection is made based on the selection information (merge index) described above. The motion information for the selected merge candidate can be used to derive motion information for the current block. The motion information for the selected merge candidate can be used as motion information for the current block.

[0103] As another example, when the (A)MVP mode is applied to the current block, the decoding device can configure the (A)MVP candidate list described below, and use the motion vector of the selected mvp candidate from among the mvp (motion vector predictor) candidates included in the (A)MVP candidate list as the mvp of the current block. The selection is made based on the selection information (mvp flag or mvp index) described above. In this case, the MVD of the current block can be derived based on the information regarding the MVD, and the motion vector of the current block can be derived based on the mvp of the current block and the MVD. Furthermore, 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 in the reference picture list for the current block can be derived as the reference picture referenced for interpretation of the current block.

[0104] On the other hand, as described later, the motion information of the current block can be derived without constructing a candidate list, in which case the motion information of the current block can be derived according to the procedure disclosed in the prediction mode described later. In this case, the candidate list configuration described above may be omitted.

[0105] The decoding device can generate predicted samples for the current block based on the motion information of the current block. In this case, the reference picture can be derived based on the reference picture index of the current block, and the predicted samples for the current block can be derived using the sample of the reference block pointed to by the motion vector of the current block on the reference picture. In this case, as described later, a further procedure of predictive sample filtering may be performed on all or some of the predicted samples for the current block.

[0106] For example, the interpretation unit 332 of the decoding device includes a prediction mode determination unit 332_1, a motion information derivation unit 332_2, and a prediction sample derivation unit 332_3. The prediction mode determination unit 332_1 determines the prediction mode for the current block based on the prediction mode information received, the motion information derivation unit 332_2 derives motion information (motion vectors and / or reference picture indexes, etc.) for the current block based on the motion information information received, and the prediction sample derivation unit 332_3 derives prediction samples for the current block.

[0107] The decoding device generates a residual sample for the current block based on the received residual information. The decoding device can generate a restored sample for the current block based on the predicted sample and the residual sample, and generate a restored picture based on this. As mentioned above, further procedures such as in-loop filtering can be applied to the restored picture thereafter.

[0108] As described above, the interpretation procedure includes an interpretation mode determination step, a motion information derivation step corresponding to the determined prediction mode, and a prediction execution (prediction sample generation) step based on the derived motion information. The interpretation procedure is performed by the encoding device and decoding device as described above. In this document, the coding device includes the encoding device and / or the decoding device.

[0109] Various interpretation modes are used to predict the current block within a picture. For example, various modes can be used, such as merge mode, skip mode, MVP (motion vector prediction) mode, affine mode, subblock merge mode, MMVD (merge with MVD) mode, and HMVP (historical motion vector prediction) mode. DMVR (decoder side motion vector refinement) mode, AMVR (adaptive motion vector resolution) mode, BCW (Bi-prediction with CU-level weight), and BDOF (Bi-directional optical flow) can be used as additional or alternative modes. The affine mode may also be called affine motion prediction mode. The MVP mode may also be called AMVP (advanced motion vector prediction) mode. In this document, motion information candidates derived from some modes and / or some modes may be included as one of the motion information related candidates for other modes. For example, an HMVP candidate may be added as a merge candidate in the merge / skip mode, or as an MVP candidate in the MVP mode.

[0110] Prediction mode information indicating the inter-prediction mode of the current block can be signaled from the encoding device to the decoding device. The prediction mode information can be included in the bitstream and received by the decoding device. The prediction mode information may include index information indicating one of a number of candidate modes. Alternatively, the inter-prediction mode may be indicated through hierarchical signaling of flag information. In this case, the prediction mode information may include one or more flags. For example, a skip flag may be signaled to indicate whether a skip mode is applicable, and if the skip mode is not applicable, a merge flag may be signaled to indicate whether a merge mode is applicable, and if the merge mode is not applicable, an MVP mode may be indicated, or further flags for additional distinctions may be signaled. Affine modes may be signaled as independent modes, or as modes dependent on merge modes or MVP modes, etc. For example, affine modes may include affine merge mode and affine MVP mode.

[0111] On the other hand, the current block is signaled with information indicating whether the aforementioned list0 (L0) prediction, list1 (L1) prediction, or bi-prediction is used in the current block (current coding unit). This information is called motion prediction direction information, inter-prediction direction information, or inter-prediction instruction information, and can be composed / encoded / signaled, for example, in the form of an inter_pred_idc syntax element. That is, the inter_pred_idc syntax element can indicate whether the aforementioned list0 (L0) prediction, list1 (L1) prediction, or bi-prediction is used in the current block (current coding unit). For the sake of explanation, in this document, the inter-prediction type (L0 prediction, L1 prediction, or BI prediction) indicated by the inter_pred_idc syntax element can be expressed as motion prediction direction. L0 prediction can also be expressed as pred_L0, L1 prediction as pred_L1, and bi-prediction as pred_BI. For example, depending on the value of the inter_pred_idc syntax element, the following prediction types can be indicated:

[0112] As mentioned above, a single picture can contain one or more slices. A slice can have one of the following slice types: I-slice (intra slice), P-slice (predictive slice), and B-slice (bi-predictive slice). The slice type can be indicated based on the slice type information. For blocks in an I-slice, only intra-prediction can be used for prediction, and inter-prediction is not used. Of course, even in this case, original sample values ​​may be coded and signaled without prediction. For blocks in a P-slice, intra-prediction or inter-prediction can be used, and if inter-prediction is used, only uni-prediction can be used. On the other hand, for blocks in a B-slice, intra-prediction or inter-prediction can be used, and if inter-prediction is used, up to the maximum bi-prediction can be used.

[0113] L0 and L1 contain reference pictures that were encoded / decoded prior to the current picture. For example, L0 may contain reference pictures that are earlier and / or later than the current picture in the POC order, and L1 may contain reference pictures that are later and / or earlier than the current picture in the POC order. In this case, L0 is assigned a reference picture index that is lower relative to the reference pictures that are earlier than the current picture in the POC order, and L1 is assigned a reference picture index that is lower relative to the reference pictures that are later than the current picture in the POC order. In the case of a B slice, biprediction may be applied, and in this case either unidirectional biprediction or bidirectional biprediction may be applied. Bidirectional biprediction may be called true biprediction.

[0114] Specifically, for example, information regarding the interprediction mode of a current block is coded and signaled at a level such as CU (CU syntax), or implicitly determined depending on the conditions. In this case, some modes are explicitly signaled, while the remaining modes are implicitly derived.

[0115] For example, the CU syntax can carry information about the (inter)predictive mode, as shown in Table 1 below.

[0116] [Table 1-1] [Table 1-2] [Table 1-3] [Table 1-4] [Table 1-5] [Table 1-6] [Table 1-7] [Table 1-8] [Table 1-9] [Table 1-10] [Table 1-11] [Table 1-12] [Table 1-13]

[0117] Here, cu_skip_flag indicates whether skip mode is currently applied to the block (CU).

[0118] A value of 0 for `pred_mode_flag` indicates that the current coding unit is coded in inter-prediction mode. A value of 1 for `pred_mode_flag` indicates that the current coding unit is coded in intra-prediction mode.

[0119] A value of 1 for `pred_mode_ibc_flag` indicates that the current coding unit is coded in IBC prediction mode. A value of 0 for `pred_mode_ibc_flag` indicates that the current coding unit is not coded in IBC prediction mode.

[0120] A value of 1 for pcm_flag[x0][y0] indicates that the pcm_sample() syntax structure exists and the transform_tree() syntax structure does not exist in the coding unit including the luma coding block at position (x0, y0). A value of 0 for pcm_flag[x0][y0] indicates that the pcm_sample() syntax structure does not exist. In other words, pcm_flag indicates whether or not PCM (pulse coding modulation) mode is applied to the current block. If PCM mode is applied to the current block, the values ​​of the original samples within the current block can be coded and signaled without the application of prediction, transformation, quantization, etc.

[0121] A value of 1 for intra_mip_flag[x0][y0] indicates that the intra prediction type for luma samples is matrix-based intra prediction (MIP). A value of 0 for intra_mip_flag[x0][y0] indicates that the intra prediction type for luma samples is not matrix-based intra prediction. In other words, intra_mip_flag indicates whether or not the MIP prediction mode (type) is applied to the current block (of luma samples).

[0122] intra_chroma_pred_mode[x0][y0] specifies the intra prediction mode for chroma samples in the current block.

[0123] `general_merge_flag[x0][y0]` indicates whether the inter prediction parameters for the current coding unit are inferred from a neighboring inter-predicted partition. Specifically, `general_merge_flag[x0][y0]` indicates that general merge is available, and a value of `general_merge_flag` of 1 means that regular merge mode, mmvd mode, and merge subblock mode (subblock merge mode) are available. For example, if `general_merge_flag` is 1, the merge data syntax is parsed from the encoded video / image information (or bitstream), and the merge data syntax is structured / coded to include information as shown in Table 2 below.

[0124] [Table 2-1] [Table 2-2] [Table 2-3]

[0125] Here, a value of regular_merge_flag[x0][y0] equal to 1 indicates that regular merge mode is used to generate the inter prediction parameters of the current coding unit. In other words, regular_merge_flag indicates whether or not the merge mode (regular merge mode) can be applied to the current block.

[0126] A value of 1 for mmvd_merge_flag[x0][y0] indicates that a merge mode with motion vector difference is used to generate the inter prediction parameters of the current coding unit. In other words, mmvd_merge_flag indicates whether MMVD is applied to the current block.

[0127] mmvd_cand_flag[x0][y0] indicates whether the first (0) or the second (1) candidate in the merging candidate list is used with the motion vector difference derived from mmvd_distance_idx[x0][y0] and mmvd_direction_idx[x0][y0].

[0128] mmvd_distance_idx[x0][y0] specifies the index used to derive MmvdDistance[x0][y0].

[0129] mmvd_direction_idx[x0][y0] specifies the index used to derive MmvdSign[x0][y0].

[0130] merge_subblock_flag[x0][y0] specifies whether the subblock-based inter prediction parameters for the current coding. In other words, merge_subblock_flag indicates whether subblock merge mode (or affine merge mode) is applied to the current block.

[0131] `merge_subblock_idx[x0][y0]` specifies the merging candidate index of the subblock-based merging candidate list.

[0132] ciip_flag[x0][y0] indicates whether the combined inter-picture merge and intra-picture prediction is applied for the current coding unit.

[0133] `merge_triangle_idx0[x0][y0]` specifies the first merging candidate index of the triangular shape-based motion compensation candidate list.

[0134] `merge_triangle_idx1[x0][y0]` specifies the second merging candidate index of the triangular shape-based motion compensation candidate list.

[0135] merge_idx[x0][y0] specifies the merging candidate index of the merging candidate list.

[0136] On the other hand, referring again to the CU syntax in Table 1, mvp_l0_flag[x0][y0] specifies the motion vector predictor index of list 0. That is, when MVP mode is applied, mvp_l0_flag indicates the candidate selected in MVP candidate list 0 for the MVP derivation of the current block.

[0137] mvp_l1_flag[x0][y0] has the same meaning as mvp_l0_flag, with l0, L0 and list 0 replaced by l1, L1 and list 1, respectively.

[0138] inter_pred_idc[x0][y0] indicates whether list0, list1, or bi-prediction is used for the current coding unit.

[0139] A value of sym_mvd_flag[x0][y0] equal to 1 indicates that the syntax elements ref_idx_l0[x0][y0] and ref_idx_l1[x0][y0] exist, and that the mvd_coding(x0, y0, refList ,cpIdx) syntax structure for refList equal to 1 does not exist. In other words, sym_mvd_flag indicates whether symmetric MVD is used in MVD coding.

[0140] ref_idx_l0[x0][y0] specifies the list 0 reference picture index for the current coding unit.

[0141] ref_idx_l1[x0][y0] has the same semantics as ref_idx_l0, with l0, L0 and list 0 replaced by l1, L1 and list 1, respectively.

[0142] A value of inter_affine_flag[x0][y0] equal to 1 indicates that for the current coding unit, when decoding a P or B slice, affine model-based motion compensation is used to generate the prediction samples of the current coding unit.

[0143] A value of cu_affine_type_flag[x0][y0] equal to 1 indicates that for the current coding unit, when decoding a P or B slice, 6-parameter affine model-based motion compensation is used to generate the prediction samples of the current coding unit. A value of cu_affine_type_flag[x0][y0] equal to 0 indicates that 4-parameter affine model-based motion compensation is used to generate the prediction samples of the current coding unit.

[0144] amvr_flag[x0][y0] indicates the resolution of the motion vector difference. The array indices x0 and y0 indicate the position (x0, y0) of the upper-left luma sample of the coding block considered relative to the upper-left luma sample of the picture. A value of 0 for amvr_flag[x0][y0] indicates that the resolution of the motion vector difference is 1 / 4 of the luma sample. A value of 1 for amvr_flag[x0][y0] indicates that the resolution of the motion vector difference is further specified by amvr_precision_flag[x0][y0]. The array indices x0, y0 specify the location (x0, y0) of the top-left luma sample of the considered coding block relative to the top-left luma sample of the picture. amvr_flag[x0][y0] equal to 0 specifies that the resolution of the motion vector difference is 1 / 4 of a luma sample. amvr_flag[x0][y0] equal to 1 specifies that the resolution of the motion vector difference is further specified by amvr_precision_flag[x0][y0].

[0145] If the value of amvr_precision_flag[x0][y0] is 0, and the value of inter_affine_flag[x0][y0] is 0, it indicates that the resolution of the motion vector difference is one integer luma sample; otherwise, it indicates that it is 1 / 16 of a luma sample. If the value of amvr_precision_flag[x0][y0] is 1, and the value of inter_affine_flag[x0][y0] is 0, it indicates that the resolution of the motion vector difference is four luma samples; otherwise, it indicates that it is one integer luma sample. The array indices x0 and y0 indicate the location (x0, y0) of the top-left luma sample of the considered coding block relative to the top-left luma sample of the picture. (amvr_precision_flag[x0][y0] equal to 0 specifies that the resolution of the motion vector difference is one integer luma sample if inter_affine_flag[x0][y0] is equal to 0, and 1 / 16 of a luma sample otherwise. amvr_precision_flag[x0][y0] equal to 1 specifies that the resolution of the motion vector difference is four luma samples if inter_affine_flag[x0][y0] is equal to 0, and one integer luma sample otherwise. The array indices x0 and y0 specify the location (x0, y0) of the top-left luma sample of the considered coding block relative to the top-left luma sample of the picture.)

[0146] bcw_idx[x0][y0] specifies the weight index of bi-prediction with CU weights.

[0147] The coding device performs interpretation using motion information of the current block. The encoding device can derive optimal motion information for the current block through a motion estimation procedure. For example, the encoding device can use the original block in the original picture for the current block to search for highly correlated similar reference blocks in fractional pixel units within a defined search range in the reference picture, thereby deriving motion information. Block similarity can be derived based on the difference in phase-based sample values. For example, block similarity is calculated based on the SAD between the current block (or the template of the current block) and the reference block (or the template of the reference block). In this case, motion information can be derived based on the reference block with the smallest SAD within the search area. The derived motion information is signaled to the decoding device in various ways based on the interpretation mode.

[0148] The coding device can derive predicted samples(s) for the current block based on the motion information. The current block containing the predicted samples may be called the predicted block.

[0149] The predicted block may include the predicted samples (predicted sample array) of the current block. If the motion vector of the current block is in fractional sample units, an interpolation procedure is performed, through which the predicted samples of the current block can be derived based on the reference samples in fractional sample units within the reference picture. When affine interpretation is applied to the current block, the coding device can generate predicted samples based on the motion vector (MV) in sample / subblock units. When biprediction is applied, predicted samples derived via a (phase-dependent) weighted sum or weighted average of predicted samples derived based on L0 prediction (i.e., prediction using the reference picture in reference picture list L0 and MVL0) and predicted samples derived based on L1 prediction (i.e., prediction using the reference picture in reference picture list L1 and MVL1) can be used as predicted samples of the current block. When biprediction is applied, if the reference picture used for L0 prediction and the reference picture used for L1 prediction are located in different temporal directions relative to the current picture (i.e., it is biprediction but corresponds to bidirectional prediction), this may be called true biprediction.

[0150] Based on the derived predicted samples, reconstructed samples and reconstructed pictures can be generated, after which procedures such as in-loop filtering are performed.

[0151] Figure 6 illustrates the spatial candidates that can be used for interpretation.

[0152] When merge mode is applied during interpretation, the movement information of the current block is not transmitted directly, but rather the movement information of the surrounding predicted blocks is used to guide the current block's movement information. Therefore, the encoding device can indicate the current block's movement information by transmitting flag information indicating that merge mode was used and a merge index indicating which surrounding predicted block is being used. This merge mode may also be called regular merge mode.

[0153] The coding device searches for merge candidate blocks to be used to guide the movement information of the current block in order to execute merge mode. For example, up to five merge candidate blocks may be available, but this embodiment is not limited to this. Information regarding the maximum number of merge candidate blocks can also be transmitted in the slice header or tile group header, but this embodiment is not limited to this. After finding the merge candidate blocks, the coding device generates a merge candidate list and can select the merge candidate block with the lowest cost among them as the final merge candidate block.

[0154] This document provides various embodiments for merge candidate blocks that constitute the merge candidate list.

[0155] The merge candidate list includes, for example, five merge candidate blocks. For example, four spatial merge candidates and one temporal merge candidate can be used. As a specific example, in the case of a spatial merge candidate, the blocks shown in Figure 6 (A0, A1, B0, B1, B2) can be used as spatial merge candidates. Hereinafter, the spatial merge candidates or spatial MVP candidates described later may be called SMVPs, and the temporal merge candidates or temporal MVP candidates described later may be called TMVPs.

[0156] The list of merge candidates for the current block is constructed, for example, based on the following procedure:

[0157] First, the coding device (encoding device / decoding device) can search for spatially surrounding blocks of the current block and insert the derived spatial merge candidates into the merge candidate list. For example, the spatially surrounding blocks include the block around the lower left corner (A0), the left side surrounding block (A1), the upper right corner surrounding block (B0), the upper side surrounding block (B1), and the upper left corner surrounding block (B2) of the current block. However, this is an example, and additional surrounding blocks such as the right side surrounding block, the lower side surrounding block, and the lower right side surrounding block can also be used as spatially surrounding blocks. The coding device can search for the spatially surrounding blocks based on priority to detect available blocks and derive the movement information of the detected blocks as the spatial merge candidates. For example, the encoding device and / or decoding device can search the five blocks shown in Figure 6 in the order A1, B1, B0, A0, B2, and sequentially index the available candidates to form a merge candidate list.

[0158] Furthermore, the coding device can search for temporally surrounding blocks of the current block and insert the derived temporal merge candidates into the merge candidate list. The temporally surrounding blocks can be located on a reference picture that is a different picture from the current picture on which the current block is located. The reference picture on which the temporally surrounding blocks are located may be called a collocated picture or col picture. The temporally surrounding blocks are searched for on the col picture in the order of the lower right corner surrounding block and the lower right center block of the co-located block relative to the current block.

[0159] On the other hand, the coding device can check whether the current number of merge candidates is less than the maximum number of merge candidates. The maximum number of merge candidates can be predefined or signaled from the encoding device to the decoding device. For example, the encoding device generates information about the maximum number of merge candidates, encodes it, and transmits it to the decoding device in bitstream form. Once the maximum number of merge candidates is filled, the process of adding candidates further may not be necessary.

[0160] If, as a result of the above check, the number of current merge candidates is less than the number of maximum merge candidates, the coding device may insert additional merge candidates into the merge candidate list. The additional merge candidates include, for example, at least one of the following: history-based merge candidate(s), pair-wise average merge candidate(s), ATMP, combined bi-predictive merge candidate(s) (if the slice / tile group type of the current slice / tile group is type B), and / or zero vector merge candidate(s).

[0161] If, as a result of the above check, the current number of merge candidates is not less than the maximum number of merge candidates, the coding device may terminate the configuration of the merge candidate list. In this case, the encoding device can select the optimal merge candidate from among the merge candidates constituting the merge candidate list based on the RD (rate-distortion) cost, and can signal selection information (e.g., merge index) pointing to the selected merge candidate to the decoding device. The decoding device can select the optimal merge candidate based on the merge candidate list and the selection information.

[0162] As previously stated, the motion information of the selected merge candidate can be used for the motion information of the current block, and based on the motion information of the current block, predicted samples of the current block can be derived. The encoding device can derive residual samples of the current block based on the predicted samples and signal residual information regarding the residual samples to the decoding device. As previously stated, the decoding device can generate restored samples based on the residual samples derived based on the residual information and the predicted samples, and based on these, can generate a restored picture.

[0163] When skip mode is applied during interpretation, the motion information of the current block can be derived in the same manner as when the merge mode described above is applied. However, when skip mode is applied, the residual signal for the block in question is omitted, and therefore, the predicted sample can be immediately used as the restored sample. The skip mode is applied, for example, when the value of the CU skip flag (cu_skip_flag) is 1.

[0164] Figure 7 illustrates the temporal candidates that can be used for interpretation.

[0165] Here, the temporal candidate refers to the aforementioned temporal merge candidate. Furthermore, the motion vectors included in the temporal candidate can also correspond to the temporal MVP candidate.

[0166] In this step, only one candidate is added to the candidate list. Particularly, in the derivation of this temporal merge candidate, a scaled motion vector is derived based on co-located CUs belonging to the collocated reference picture (may be referred to as colPic). The reference picture list to be used for derivation of the co-located CU is explicitly signaled in the slice header.The scaled motion vector for the temporal merge candidate is obtained as illustrated by the dotted line in Figure 7, which is scaled from the motion vector of the co-located CU using the POC (picture order count) distances, tb, and td, where tb is defined as the POC difference between the reference picture of the current picture and the current picture, and td is defined as the POC difference between the reference picture of the co-located picture and the co-located picture. The reference picture index of the temporal merge candidate is set to zero.

[0167] In addition to the merge mode, in which implicitly derived motion information is directly used for prediction sample generation of the current CU, a merge mode with motion vector differences (MMVD) is introduced to the VVC. Similar motion information derivation methods are used for the skip mode and the merge mode, so MMVD can be applied to the skip mode. An MMVD flag (e.g., mmvd_flag) is signaled immediately after sending a skip flag and a merge flag to indicate whether the MMVD mode is applied to the CU.

[0168] In MMVD, after a merge candidate is selected, it is further refined by the signaled MVD information. When an MMVD is applied to the current block (i.e., when the mmvd_flag is equal to 1), further information about the MMVD may be signaled.

[0169] The further information includes a merge candidate flag (e.g., mmvd_merge_flag) indicating whether the first (0) or the second (1) candidate in the merging candidate list is used with the motion vector difference, an index to specify motion magnitude (e.g., mmvd_distance_idx), and an index for indicating motion direction (e.g., mmvd_direction_idx). In MMVD mode, one for the first two candidates in the merge list is selected to be used as the MV basis. The merge candidate flag is signaled to specify which flag is used.

[0170] The distance index indicates motion magnitude information and shows a predetermined offset from the starting point.

[0171] The offset is added to either the horizontal or vertical component of the starting motion vector (MV). The relationship between the distance index and the predefined offset is shown in Table 3.

[0172] [Table 3]

[0173] Here, slice_fpel_mmvd_enabled_flag equal to 1 specifies that merge mode with motion vector difference uses integer sample precision in the current slice. slice_fpel_mmvd_enabled_flag equal to 0 specifies that merge mode with motion vector difference can use fractional sample precision in the current slice. When not present, the value of slice_fpel_mmvd_enabled_flag is inferred to be 0. The `slice_fpel_mmvd_enabled_flag` syntax element may be signaled through (or comprised in) a slice header.

[0174] The direction index indicates the direction of the MVD relative to the starting point. The direction index can represent four directions, as shown in Table 4. The meaning of the MVD sign can vary depending on the starting information of the MVs. When the starting MVs is an unprediction MV or biprediction MVs with both lists point to the same side of the current picture (e.g., the points of content (POCs) of two references are both larger than the POC of the current picture, or both are smaller than the POC of the current picture), the sign in Table 4 specifies the sign of the MV offset added to the starting MV.When the starting MVs are bi-prediction MVs with the two MVs pointing to the different sides of the current picture (i.e., the POC of one reference is larger than the POC of the current picture, and the POC of the other reference is smaller than the PCO of the current picture), the sign in Table 4 indicates the sign of the MV offset added to the list0 MV component of the starting MV, and the sign for the list1 MV has the opposite value.

[0175] [Table 4]

[0176] The two components of the merge plus MVD offset MmvdOffset[x0][y0] are derived as follows:

[0177]

number

[0178] Figure 8 illustrates a subblock-based temporal motion vector prediction process that can be used during interpretation.

[0179] Subblock-based temporal motion vector prediction (SbTMVP) method can be used for inter prediction. Similar to MVP (temporal motion vector prediction), SbTMVP uses the motion field in the collocated picture to improve motion vector prediction and merge mode for CUs in the current picture. The same collocated picture used by TMVP is used for SbTVMP. SbTMVP differs from TMVP in the following two main aspects.

[0180] 1. TMVP predicts motion at the CU level, while SbTMVP predicts motion at the sub-CU level.

[0181] 2. While TMVP fetches the temporal motion vectors from the collocated block in the collocated picture (the collocated block is the bottom-right or center (below-right center) block relative to the current CU), SbTMVP applies a motion shift before fetching the temporal motion information from the collocated picture (where the motion shift is obtained from the motion vector of one of the spatially neighboring blocks of the current CU).

[0182] Figure 8 shows the SbTMVP process. SbTMVP predicts the motion vectors of the sub-CUs within the current CU in two steps. In the first step, the spatial neighbor A1 is examined. If A1 has a motion vector that uses the collocated picture as its reference picture, this motion vector (may be referred to as a temporal MV (tempVM)) is selected as the motion shift to be applied. If no such motion is identified, then the motion shift is set to (0, 0).

[0183] In the second step, the motion shift identified in Step 1 is applied (i.e., added to the current block's coordinates) to obtain sub-CU-level motion information (motion vectors and reference indices) from the collocated picture as shown in Figure 8. The example in Figure 8 assumes the motion shift is set to block A1's motion. Then, for each sub-CU, the motion information of its corresponding block (the smallest motion grid that covers the center sample) in the collocated picture is used to derive the motion information for the sub-CU.The center sample (below right center sample) may correspond to a below-right sample among 4 central samples in the sub-CU when the sub-block has an even length, width, and height.

[0184] After the motion information of the collocated sub-CU is identified, it is converted to the motion vectors and reference indices of the current sub-CU in a manner similar to the TMVP process, where temporal motion scaling may be applied to align the reference pictures of the temporal motion vectors with the reference pictures of the current CU.

[0185] A combined sub-block based merge list containing both SbTVMP candidates and affine merge candidates can be used for signaling affine merge mode (may be referred to as sub-block (based) merge mode). The SbTVMP mode is enabled / disabled by a Sequence Parameter Set (SPS) flag. If the SbTMVP mode is enabled, the SbTMVP predictor is added as the first entry in the list of sub-block merge candidates, followed by the affine merge candidates. The maximum allowed size of the affine merge candidate list may be 5.

[0186] In SbTMVP, the sub-CU size is fixed to 8x8, and, as in affine merge mode, SbTMVP mode is only applicable to CUs where both width and height are greater than or equal to 8.

[0187] The encoding logic for the additional SbTMVP merge candidate is the same as for the other merge candidates; that is, for each CU in a P or B slice, an additional RD check may be performed to determine whether to use the SbTMVP candidate.

[0188] Figure 9 illustrates partitioning modes that can be applied to interpretation.

[0189] A triangle partition mode may be used for inter prediction. The triangle partition mode may only be applied to CUs that are 8x8 or larger. The triangle partition mode can be signaled using a CU-level flag as one kind of merge mode, with other merge modes including the regular merge mode, the MMVD mode, the CIIP mode, and the subblock merge mode.

[0190] When this mode is used, a CU may be split evenly into two triangle-shaped partitions, using either the diagonal split or the anti-diagonal split as shown in Figure 9. Each triangle partition in the CU is inter-predicted using its own motion; only uni-prediction is allowed for each partition, that is, each partition has one motion vector and one reference index. The uni-prediction motion constraint is applied to ensure that, same as the conventional bi-prediction, only two motion-compensated predictions are needed for each CU.

[0191] If triangle partition mode is used for the current CU, then a flag indicating the orientation of the triangle partition (diagonal or anti-diagonal) and two merge indices (one for each partition) are further signaled. The number of maximum TPM candidate sizes is signaled explicitly at the slice level and specifies syntax binarization for TPM merge indices. After predicting each of the triangle partitions, the sample values ​​along the diagonal or anti-diagonal edge are adjusted using a blending process with adaptive weights. This is the prediction signal for the whole CU, and the transform and quantization processes will be applied to the whole CU as in other prediction modes.Finally, the motion field of a CU predicted using the triangle partition mode is stored in 4x4 units. The triangle partition mode is not used in combination with SBT (subblock transform); that is, when the signaled triangle mode is equal to 1, the cu_sbt_flag is derived as 0 without signaling.

[0192] The uni-prediction candidate list is derived directly from the merge candidate list constructed as described above.

[0193] After predicting each triangle partition using its own motion, blending is applied to the two prediction signals to derive samples around the diagonal or anti-diagonal edge.

[0194] On the other hand, combined inter and intra prediction can be applied to a current block. An additional flag (e.g., ciip_flag) may be signaled to indicate whether the combined inter / intra prediction (CIIP) mode is applied to the current CU. For example, when a CU is coded in merge mode, if the CU contains at least 64 luma samples (that is, the product of the CU width and CU height is equal to or greater than 64 luma samples), and if both the CU width and CU height are less than 128 luma samples, the additional flag is signaled to indicate whether the combined inter / intra prediction (CIIP) mode is applied to the current CU. As its name indicates, the CIIP prediction combines an inter prediction signal with an intra prediction signal.The inter prediction signal in the CIIP mode P_inter is derived using the same inter prediction process applied to regular merge mode, and the intra prediction signal P_intra is derived following the regular intra prediction process with the planar mode. Then, the intra and inter prediction signals are combined using weighted averaging, where the weight value is calculated depending on the coding modes of the top and left neighboring blocks as follows.

[0195] If the top neighbor is available and intracoded, then set isIntraTop to 1; otherwise, set isIntraTop to 0.

[0196] If the left neighbor is available and intracoded, then set isIntraLeft to 1; otherwise, set isIntraLeft to 0.

[0197] If (isIntraLeft + isIntraLeft) is 2, then the weight value (wt) is set to 3.

[0198] Otherwise, if (isIntraLeft + isIntraLeft) is equal to 1, then wt is set to 2.

[0199] Otherwise, wt will be set to 1.

[0200] The CIIP prediction is formed as follows:

[0201]

number

[0202] On the other hand, in order to generate predictive blocks in the coding device, motion information can be induced based on the aforementioned regular merge mode, skip mode, SbTMVP mode, MMVD mode, triangle partition mode (partitioning mode), and / or CIIP mode. Each mode is enabled / disabled via an on / off flag for that mode included in the sequence parameter set (SPS). If the on / off flag for a particular mode is disabled, the encoding device will not signal the syntax to be sent explicitly for that predictive mode at the CU or PU level.

[0203] This document discloses a method for signaling syntax, taking into account the on / off and application methods of merge / skip modes, in order to remove redundant syntax signaling.

[0204] For example, in the case of the regular_merge_flag, under conditions where MMVD, subblock merge, CIIP merge, and triangle merge are not allowed, there are no other possible options besides the regular merge mode, so there is no need to signal the flag (e.g., the regular_merge_flag).

[0205] Additionally, mmvd-related flags (e.g., mmvd_merge_flag) do not need to be signaled under conditions where subblock merges, CIIP merges, and triangle merges are not permitted.

[0206] Subblock-related flags (e.g., merge_subblock_flag) do not need to be signaled under conditions where CIIP merges and triangle merges are not permitted.

[0207] For CIIP-related flags (e.g., ciip_flag), signaling is not necessary under conditions where triangle merging is not permitted.

[0208] Therefore, according to the merge data syntax in Table 2, if all or some of the specific modes for merge / skip modes are disabled, a problem arises where the on / off flag is signaled redundantly. Accordingly, in this document, the following method is used to prevent the same information (flags) from being signaled redundantly during the process of selecting the merge mode to be applied to the current block.

[0209] The following drawings were created to illustrate a specific example of this document. The names of specific devices and signals / information shown in the drawings are presented illustratively, and the technical features of this specification are not limited to the specific names used in the following drawings.

[0210] Figures 10 and 11 schematically illustrate an example of a video / image encoding method and related components, including an interpretation method according to the embodiments of this document.

[0211] The encoding method shown in Figure 10 is performed by the encoding device 200 disclosed in Figure 2. Specifically, for example, steps S1000 to S1030 in Figure 10 are performed by the prediction unit 220 of the encoding device 200, step S1040 is performed by the residual processing unit 230 of the encoding device 200, and step S1050 is performed by the entropy encoding unit 240 of the encoding device 200. The encoding method disclosed in Figure 10 includes the embodiments described above in this document.

[0212] Specifically, referring to Figures 10 and 11, the prediction unit of the encoding device determines the prediction mode for the current block (S1000). As an example, when interpretation is applied to the current block, the prediction unit of the encoding device can determine one of the following as the prediction mode for the current block: regular merge mode, skip mode, MMVD mode, subblock merge mode, partitioning mode, or CIIP mode.

[0213] Here, the regular merge mode is defined as a mode that uses motion information of surrounding blocks to guide the motion information of the current block. The skip mode is defined as a mode that uses the predicted block as the restored block. The MMVD mode is applied to the merge mode or the skip mode and is defined as a merge (or skip) mode that utilizes motion vector differences. The subblock merge mode is defined as a merge mode based on subblocks. The partitioning mode is defined as a mode that divides the current block into two partitions (diagonal or semi-diagonal) and performs prediction. The CIIP mode is defined as a mode that combines inter-picture merge and intra-picture prediction.

[0214] The prediction unit of the encoding device constructs a merge candidate list based on the prediction mode of the current block (S1010). For example, if the prediction mode for the current block is determined to be the (regular) merge mode, the prediction unit of the encoding device constructs a merge candidate list (or motion information candidate list) based on the spatially and temporally surrounding blocks of the current block, and generates motion information based on it.

[0215] The prediction unit of the encoding device derives motion information for the current block based on the merge candidate list (S1020). The motion information includes a motion vector and a reference picture index. For example, if the prediction mode for the current block is determined to be the (regular) merge mode, the prediction unit of the encoding device constructs a merge candidate list (or motion information candidate list) based on the spatially surrounding blocks and temporally surrounding blocks of the current block, and generates motion information based on it. Here, the prediction unit of the encoding device searches for blocks similar to the current block within a certain area (search area) of the reference picture by motion estimation, derives a reference block whose difference from the current block is the minimum or below a certain standard, and derives a reference picture index that points to the reference picture in which the reference block is located based on this. Then, it derives a motion vector based on the difference in position between the reference block and the current block.

[0216] The prediction unit of the encoding device derives a predicted sample (predicted block) of the current block based on the prediction mode of the current block and the motion information of the current block (S1030). It also generates information about the prediction mode based on the prediction mode. Here, the information about the prediction mode includes inter / intra prediction classification information, inter prediction mode information, etc., and includes various syntax elements related thereto.

[0217] The residual processing unit of the encoding device derives a residual sample based on the original sample (original block) for the current block and the predicted sample (predicted block) for the current block (S1040). Then, it derives information about the residual sample based on the residual sample.

[0218] The encoding unit of the encoding device encodes video information including information about the residual sample and information about the prediction mode (S1050). The video information includes partitioning-related information, information about the prediction mode, residual information, in-loop filtering-related information, and various syntax elements related thereto. The information encoded by the encoding unit of the encoding device is output in bitstream form. The bitstream is transmitted to the decoding device via a network or storage medium.

[0219] For example, the video information includes information about various parameter sets, such as the Adaptation Parameter Set (APS), Picture Parameter Set (PPS), Sequence Parameter Set (SPS), or Video Parameter Set (VPS). The video information also includes information about the prediction mode of the current block, such as the coding unit syntax and merge data syntax. Here, the sequence parameter set includes a CIIP (combined inter-picture merge and intra-picture prediction) enabled flag and an enable flag for the partitioning mode. The coding unit syntax includes a CU skip flag indicating whether or not a skip mode is applied to the current block.

[0220] According to one embodiment, as an example, the encoding device may apply some or all of the signaling conditions and associated semantics of the regular merge flag (regular_merge_flag), the signaling conditions and associated semantics of the MMVD merge flag (MMVD_merge_flag), the signaling conditions and associated semantics of the merge subblock flag (merge_subblock_flag), and / or the signaling conditions and associated semantics of the CIIP flag, based on the conditions under which MMVD (MMVD mode) is allowed (MMVDAllowed), the conditions under which merge subblock (subblock merge mode) is allowed (MergeCIIPAllowed), and / or the conditions under which merge triangle (partitioning mode) is allowed (MergeTriangleAllowed), so as to prevent duplicate transmission of the same syntax.

[0221] For this reason, the merge data syntax is structured as shown in Table 5 below, as an example.

[0222] [Table 5-1] [Table 5-2]

[0223] In Table 5, general_merge_flag[x0][y0] indicates whether the inter-prediction parameters for the current coding unit are inferred from a neighboring inter-predicted partition. The array indices x0, y0 specify the location (x0, y0) of the top-left luma sample of the considered coding block relative to the top-left luma sample of the picture.

[0224] If general_merge_flag[x0][y0] does not exist, it is inferred as follows:

[0225] -If the value of cu_skip_flag[x0][y0] is 1, general_merge_flag[x0][y0] is derived as 1.

[0226] -Otherwise, general_merge_flag[x0][y0] is inferred to be equal to 0.

[0227] In Table 5, the conditions under which MMVD (MMVD mode) is allowed (MMVDAllowed), the conditions under which MergeSubBlock (Subblock Merge mode) is allowed (MergeSubBlockAllowed), the conditions under which MergeCIIP (CIIP mode) is allowed (MergeCIIPAllowed), and the conditions under which MergeTriangle (Partitioning mode) is allowed (MergeTriangleAlowed) are derived according to the following conditions, respectively.

[0228] If all of the following conditions are true, the variable MMVDAllowed is set to true.

[0229] - The value of general_merge_flag[x0][y0] is 1 (general_merge_flag[x0][y0] is equal to 1)

[0230] - The value of sps_mmvd_enabled_flag is 1 (sps_mmvd_enabled_flag is equal to 1)

[0231] - The product of the current block's height and width is greater than 32 (cbWidth * cbHeight is greater than 32)

[0232] If all of the following conditions are true, the variable MMVDSubblockAllowed is set to true.

[0233] - The value of general_merge_flag[x0][y0] is 1 (general_merge_flag[x0][y0] is equal to 1)

[0234] - The maximum number of subblock merge candidates is greater than 0 (MaxNumSubblockMergeCand > 0)

[0235] - The block width is greater than or equal to 8 and the block height is greater than or equal to 8.

[0236] If all of the following conditions are true, the variable MergeCIIPAllowed is set equal to true.

[0237] - The value of general_merge_flag[x0][y0] is 1 (general_merge_flag[x0][y0] is equal to 1)

[0238] - The value of sps_ciip_enabled_Flag is 1 (sps_ciip_enabled_Flag is equal to 1)

[0239] - The value of cu_skip_flag[x0][y0] is 0 (cu_skip_flag[x0][y0] is equal to 0)

[0240] - The product of the current block's width and height is 64 or greater (cbWidth * cbHeight is greater than or equal to 64)

[0241] - The current block width is smaller than 128 and the current block height is smaller than 128.

[0242] If all of the following conditions are true, the variable MergeTriangleAllowed is set equal to true.

[0243] - The value of general_merge_flag[x0][y0] is 1 (general_merge_flag[x0][y0] is equal to 1)

[0244] - The value of sps_triangle_enalbed_Flag is 1 and the slice type is B.

[0245] - The maximum number of triangle merge candidates is 2 or greater (NaxNumTriangleMergeCand is greater than or equal to 2)

[0246] - The product of the current block's width and height is 64 or greater (cbWidth * cbHeight is greater than or equal to 64)

[0247] Of the above conditions, MMVDAllowed means that MMVD is permissible, and in this case, the condition based on block size is currently possible only when the blocks are not 4x8 and 8x4. However, if uni-prediction MMVD is permissible in 4x8 and / or 8x4 blocks, the compression efficiency can be improved, so the MMVDAllowed condition can be changed as follows.

[0248] If all of the following conditions are true, the variable MMVDAllowed is set to true.

[0249] -The value of general_merge_flag[x0][y0] is 1.

[0250] - The value of sps_mmvd_enabled_flag is 1 (sps_mmvd_enabled_flag is equal to 1)

[0251] On the other hand, a value of 1 for the regular_merge_flag[x0][y0] indicates that regular merge mode is used to generate the inter prediction parameters of the current coding unit (current block). The array indices x0, y0 specify the location (x0, y0) of the top-left luma sample of the considered coding block relative to the top-left luma sample of the picture.

[0252] Referring to Table 5, a regular merge plug is included in the video information and signaled in the form of a bitstream if at least one of the following conditions is 1: MMVD mode-based condition (MMVDAllowed), subblock merge mode-based condition (MergeSubBlockAllowed), CIIP mode-based condition (MergeCIIPAllowed), and partitioning mode-based condition (MergeTriangleAllowed).

[0253] For example, a regular merge plug can be included in the bitstream if CIIP is available. CIIP availability can be determined based on at least one of the general merge flag, the CIIP available flag, the current block size, and the CU skip flag. For example, the regular merge flag is included in the bitstream if the value of the general merge flag is 1, or the value of the CIIP available flag is 1, or the product of the current block height and the current block width is 64 or greater, or the current block height and the current block width are both less than 128, or the value of the skip flag is 0. Alternatively, the regular merge flag is included in the bitstream if all the conditions based on the general merge flag, the CIIP available flag, the current block size, and the CU skip flag are met.

[0254] As another example, the regular merge flag may be included in the bitstream if a partitioning mode is available. Whether a partitioning mode is available is determined based on at least one of the general merge flag, a partitioning mode availability flag indicating whether a partitioning mode is available, and information about the current block. For example, the regular merge flag is included in the bitstream if the value of the general merge flag is 1, or the value of the partitioning mode availability flag is 1, or the product of the height and width of the current block is 64 or greater, or the slice type of the current block is a B slice, or the maximum number of partitioning mode candidates is 2 or greater. Alternatively, the regular merge flag is included in the bitstream if all of the above conditions are met.

[0255] When regular_merge_flag[x0][y0] is not present in the merge data syntax, it is inferred as follows.

[0256] If all of the following conditions are true, regular_merge_flag[x0][y0] is inferred to be equal to 1.

[0257] - MMVDAllowed is equal to 0

[0258] - MergeSubBlockAllowed is equal to 0

[0259] - MergeCIIPAllowed is equal to 0

[0260] - MergeTriangleAllowed is equal to 0

[0261] - Otherwise, regular_merge_flag[x0][y0] is inferred to be equal to 0.

[0262] On the other hand, a value of 1 for the MMVD merge flag indicates that a merge mode with motion vector difference is used to generate the inter prediction parameters of the current coding unit (current block). The array indices x0 and y0 indicate the location (x0, y0) of the top-left luma sample of the coding block considered relative to the top-left luma sample of the picture.

[0263] Referring to Table 5, the MMVD merge flag is included in the video information and signaled in bitstream form if at least one of the following conditions is 1: MMVD mode-based condition (MMVDAllowed), subblock merge mode-based condition (MergeSubBlockAllowed), CIIP mode-based condition (MergeCIIPAllowed), and partitioning mode-based condition (MergeTriangleAllowed).

[0264] When mmvd_merge_flag[x0][y0] is not present in the merge data syntax, it is inferred as follows:

[0265] If all of the following conditions are true, the value of mmvd_merge_flag[x0][y0] is inferred to be equal to 1.

[0266] - The value of regular_merge_flag[x0][y0] is 0.

[0267] - The value of MMVDAllowed is 1 (MMVDAllowed is equal to 0).

[0268] - The value of MergeSubBlockAllowed is 0 (MergeSubBlockAllowed is equal to 0)

[0269] - The value of MergeCIIPAllowed is 0 (MergeCIIPAllowed is equal to 0)

[0270] - The value of MergeTriangleAllowed is 0 (MergeTriangleAllowed is equal to 0)

[0271] Otherwise, the value of the MMVD merge flag is derived as 0.

[0272] mmvd_cand_flag[x0][y0] indicates whether the first (0) or the second (1) candidate in the merging candidate list is used with the motion vector difference derived from mmvd_distance_idx[x0][y0] and mmvd_direction_idx[x0][y0]. The array indices x0 and y0 indicate the location (x0, y0) of the top-left luma sample of the coding block considered relative to the top-left luma sample of the picture. When mmvd_cand_flag[x0][y0] is not present, it is inferred to be equal to 0.

[0273] mmvd_distance_idx[x0][y0] specifies the index used to derive MMVDDistance[x0][y0] as specified in Table 3. The array indices x0, y0 specify the location (x0, y0) of the top-left luma sample of the considered coding block relative to the top-left luma sample of the picture.

[0274] mmvd_direction_idx[x0][y0] specifies the index used to derive MMVDSign[x0][y0] as specified in Table 4. The array indices x0, y0 specify the location (x0, y0) of the top-left luma sample of the considered coding block relative to the top-left luma sample of the picture.

[0275] The two components of the merge plus MVD offset MMVDOffset[x0][y0] are derived as shown in Equation 1.

[0276] On the other hand, the merge_subblock_flag[x0][y0] indicates whether the subblock-based inter prediction parameters for the current coding unit are inferred from neighboring blocks. The array indices x0, y0 specify the location (x0, y0) of the top-left luma sample of the considered coding block relative to the top-left luma sample of the picture.

[0277] Referring to Table 5, the merge subblock flag is included in the video information and signaled in bitstream form if at least one of the following conditions is 1: MergeSubBlockAllowed (based on subblock merging mode), MergeCIIPAllowed (based on CIIP mode), and MergeTriangleAllowed (based on partitioning mode).

[0278] When merge_subblock_flag[x0][y0] is not present in the merge data syntax, it is inferred as follow.

[0279] If all of the following conditions are true, merge_subblock_flag[x0][y0] is inferred to be equal to 1.

[0280] - regular_merge_flag[x0][y0] is equal to 0

[0281] - mmvd_merge_flag[x0][y0] is equal to 0

[0282] - MergeSubBlockAllowed is equal to 0

[0283] - MergeCIIPAllowed is equal to 0

[0284] - MergeTriangleAllowed is equal to 0

[0285] Otherwise, merge_subblock_flag[x0][y0] is inferred to be equal to 0.

[0286] `merge_subblock_idx[x0][y0]` specifies the merging candidate index of the subblock-based merging candidate list, where x0 and y0 specify the location (x0, y0) of the top-left luma sample of the considered coding block relative to the top-left luma sample of the picture.

[0287] If merge_subblock_idx[x0][y0] does not exist, it is inferred to bequal to 0.

[0288] On the other hand, ciip_flag[x0][y0] indicates whether the combined inter-picture merge and intra-picture merge is currently applied to the coding unit. The array indices x0 and y0 specify the location (x0, y0) of the top-left luma sample of the considered coding block relative to the top-left luma sample of the picture.

[0289] Referring to Table 5, the CIIP flag is included in the video information and signaled in the form of a bitstream if at least one of the conditions based on CIIP mode (MergeCIIPAllowed) and the condition based on partitioning mode (MergeTriangleAllowed) is 1.

[0290] For example, the CIIP flag may be included in the bitstream if a partitioning mode is available. Whether a partitioning mode is available can be determined based on at least one of the following: the general merge flag, the partitioning mode availability flag indicating whether a partitioning mode is available, and information about the current block. For example, the CIIP flag may be included in the bitstream if the value of the general merge flag is 1, or the value of the partitioning mode availability flag is 1, or the product of the height and width of the current block is 64 or greater, or the slice type of the current block is a B slice, or the maximum number of partitioning mode candidates is 2 or greater. Alternatively, the CIIP flag may be included in the bitstream if all of the above conditions are met.

[0291] If ciip_flag[x0][y0] is not present in the merge data syntax, it is inferred as follows:

[0292] If all the following conditions are true, the value of the CIIP flag is derived to be 1.

[0293] - The value of MergeCIIPAllowed is 0 (MergeCIIPAllowed is equal to 0)

[0294] - The value of MergeTriangleAllowed is 0 (MergeTriangleAllowed is equal to 0)

[0295] Otherwise, the value of the CIIP flag is derived as 0.

[0296] When ciip_flag[x0][y0] is equal to 1, the variable IntraPredModeY[x][y] with x = xCb + cbWidth - 1 and y = yCb + cbHeight - 1 is set to INTRA_PLANAR.

[0297] The variable MergeTriangleFlag[x0][y0] indicates whether triangular shape-based motion compensation is used to generate the prediction samples of the current coding unit when decoding a B slice, and is derived as follows.

[0298] If all the following conditions are true, the value of MergeTriangleFlag[x0][y0] is set to 1.

[0299] - The value of MergeTriangleAllowed is 1 (MergeTriangleAllowed is equal to 1)

[0300] - The value of regular_merge_flag[x0][y0] is 0 (regular_merge_flag[x0][y0] is equal to 0)

[0301] - The value of mmvd_merge_flag[x0][y0] is 0 (mmvd_merge_flag[x0][y0] is equal to 0)

[0302] - The value of merge_subblock_flag[x0][y0] is 0 (merge_subblock_flag[x0][y0] is equal to 0)

[0303] -The value of ciip_flag[x0][y0] is 0 (ciip_flag[x0][y0] is equal to 0)

[0304] Otherwise, the value of MergeTriangleFlag[x0][y0] is set to 0.

[0305] Figures 12 and 13 schematically illustrate an example of a video / image decoding method and related components, including an interpretation method according to the embodiments of this document.

[0306] The decoding method disclosed in Figure 12 is performed by the decoding device 300 disclosed in Figures 3 and 13. Specifically, for example, steps S1200 to S1230 in Figure 12 are performed by the prediction unit 330 of the decoding device 300. The decoding method disclosed in Figure 12 includes the embodiments described above in this document.

[0307] As shown in Figures 12 and 13, the decoding device obtains information regarding the prediction mode of the current block from the bitstream and determines the prediction mode of the current block based on this information (S1200). Specifically, the entropy decoding unit 310 of the decoding device derives residual information and information regarding the prediction mode from the signal received in bitstream form from the encoding device shown in Figure 2. Here, the information regarding the prediction mode may also be called prediction-related information. The information regarding the prediction mode includes inter / intra prediction classification information, inter prediction mode information, etc., and includes various syntax elements related thereto.

[0308] The bitstream includes video information containing information about various parameter sets, such as an adaptation parameter set (APS), a picture parameter set (PPS), a sequence parameter set (SPS), or a video parameter set (VPS). The video information may further include information about the prediction mode of the current block, such as a coding unit syntax and a merge data syntax. The sequence parameter set includes a CIIP availability flag and an availability flag for the partitioning mode. The coding unit syntax includes a CU skip flag indicating whether a skip mode is applied to the current block.

[0309] The prediction unit 320 of the decoding device constructs a list of motion information candidates (or merge candidate list) for the current block based on the prediction mode of the current block (S1210). It also selects a merge candidate from the motion information candidate list based on candidate selection information (merge index) obtained from the bitstream, and derives the motion information of the current block using the motion information of the selected merge candidate (S1220).

[0310] Once the motion information of the current block is derived, the prediction unit of the decoding device generates a predicted sample of the current block based on the motion information of the current block (S1230).

[0311] Meanwhile, the residual processing unit 320 of the decoding device generates residual samples based on the residual information obtained from the bitstream.

[0312] The addition unit 340 of the decoding device generates a reconstructed sample based on the predicted sample generated by the prediction unit 330 and the residual sample generated by the residual processing unit 320. The reconstructed picture is generated based on the reconstructed sample. Subsequently, in-loop filtering procedures such as deblocking filtering, SAO and / or ALF procedures can be applied to the reconstructed picture as needed to improve subjective / objective image quality.

[0313] In one embodiment, when determining the prediction mode of the current block, the prediction unit of the decoding device can obtain or parse a regular merge flag from the bitstream if at least one of the following conditions is 1: the condition based on the MMVD mode (MMVDAllowed), the condition based on the subblock merge mode (MergeSubBlockAllowed), the condition based on the CIIP mode (MergeCIIPAllowed), and the condition based on the partitioning mode (MergeTrrangleAllowed).

[0314] As an example, a decoding device can parse a regular merge plug from a bitstream if CIIP is available. CIIP availability can be determined based on at least one of the following: the general merge flag, the CIIP availability flag, the current block size, and the CU skip flag. For example, the decoding device determines that CIIP is available if the value of the general merge flag is 1, or the value of the CIIP availability flag is 1, or the product of the current block height and width is 64 or greater, or the current block height and width are both less than 128, or the value of the skip flag is 0. Alternatively, the decoding device determines that CIIP is available if all the conditions based on the general merge flag, the CIIP availability flag, the current block size, and the CU skip flag are met.

[0315] As another example, a decoding device may parse a regular merge flag from a bitstream if a partitioning mode is available. The availability of a partitioning mode is determined based on at least one of the general merge flag, a partitioning mode availability flag indicating whether or not a partitioning mode is available, and information about the current block. For example, the decoding device determines that a partitioning mode is available if the value of the general merge flag is 1, or the value of the partitioning mode availability flag is 1, or the product of the height and width of the current block is 64 or more, or the slice type of the current block is a B slice, or the maximum number of partitioning mode candidates is 2 or more. Alternatively, the decoding device determines that a partitioning mode is available if all of the above conditions are met.

[0316] On the other hand, in determining the prediction mode of the current block, the prediction unit of the decoding device may also obtain or parse the MMVD merge flag from the bitstream if at least one of the following conditions is 1: the condition based on the MMVD mode (MMVDAllowed), the condition based on the subblock merge mode (MergeSubBlockAllowed), the condition based on the CIIP mode (MergeCIIPAllowed), and the condition based on the partitioning mode (MerlgeTriangleAllowed).

[0317] Furthermore, in determining the prediction mode of the current block, the prediction unit of the decoding device can obtain or parse the merge subblock flag from the bitstream if at least one of the following conditions is 1: the condition based on the subblock merge mode (MergeSubBlockAllowed), the condition based on the CIIP mode (MergeCIIPAllowed), and the condition based on the partitioning mode (MergeTriangleAllowed).

[0318] Furthermore, in determining the prediction mode of the current block, the prediction unit of the decoding device can obtain or parse the CIIP flag from the bitstream if at least one of the conditions based on the CIIP mode (MergeCIIPAllowed) and the partitioning mode (MergeTriangleAllowed) is 1. For example, the decoding device can parse the CIIP flag from the bitstream if the partitioning mode is available. Whether the partitioning mode is available is determined based on at least one of the general merge flag, the partitioning mode availability flag indicating whether the partitioning mode is available or not, and information about the current block. For example, the decoding device determines that the partitioning mode is available if the value of the general merge flag is 1, or the value of the partitioning mode availability flag is 1, or the product of the height and width of the current block is 64 or more, or the slice type of the current block is a B slice, or the maximum number of partitioning mode candidates is 2 or more. Alternatively, the decoding device determines that partitioning mode is available if all of the above conditions are met.

[0319] In the embodiments described above, the method is explained based on a flowchart as a series of steps or blocks, but the embodiments are not limited to the order of the steps, and some steps may occur in a different order or simultaneously with other steps than those described above. Furthermore, those skilled in the art will understand that the steps shown in the flowchart are not exclusive, and that different steps may be included, or one or more steps in the flowchart may be omitted without affecting the scope of the embodiments described herein.

[0320] The methods according to the embodiments of this document described above can be implemented in software form, and the encoding and / or decoding devices relating to this document may be included in, for example, video processing devices such as TVs, computers, smartphones, set-top boxes, and display devices.

[0321] In this document, when embodiments are implemented in software, the methods described above can be implemented by modules (processes, functions, etc.) that perform the functions described above. These modules are stored in memory and can be executed by a processor. The memory may be internal or external to the processor and may be connected to the processor by various well-known means. The processor may include an ASIC (application-specific integrated circuit), other chipsets, logic circuits, and / or data processing devices. The memory may include ROM (read-only memory), RAM (random access memory), flash memory, memory cards, storage media, and / or other storage devices. That is, the embodiments described in this document may be implemented on a processor, microprocessor, controller, or chip. For example, the functional units shown in each drawing may be implemented on a computer, processor, microprocessor, controller, or chip. In this case, information on instructions or algorithms for implementation may be stored on a digital storage medium.

[0322] Furthermore, decoding and encoding devices to which the embodiments of this document apply may include multimedia broadcasting transceivers, mobile communication terminals, home cinema video equipment, digital cinema video equipment, surveillance cameras, video dialogue devices, real-time communication devices such as video communications, mobile streaming devices, storage media, camcorders, customized video (VoD) service providers, OTT video (Over the Top Video) devices, internet streaming service providers, 3D video devices, VR (virtual reality) devices, AR (argumente reality) devices, video telephone video devices, transportation terminals (e.g., vehicle terminals (including autonomous vehicles), airplane terminals, ship terminals, etc.), and medical video equipment, and may be used to process video signals or data signals. For example, OTT video (Over the Top Video) devices may include game consoles, Blu-ray players, internet access TVs, home theater systems, smartphones, tablet PCs, DVRs (Digital Video Recorders), etc.

[0323] Furthermore, the processing methods to which the embodiments(et) of this document apply can be produced in the form of programs executed on a computer and stored on a computer-readable recording medium. Multimedia data having data structures according to the embodiments of this document can also be stored on a computer-readable recording medium. The computer-readable recording medium includes all types of storage devices and distributed storage devices that store data to be read by a computer. The computer-readable recording medium may include, for example, Blu-ray discs (BDs), general-purpose serial buses (USBs), ROMs, PROMs, EPROMs, EEPROMs, RAMs, CD-ROMs, magnetic tapes, floppy disks, and optical data storage devices. The computer-readable recording medium also includes media embodied in the form of carrier waves (e.g., transmission over the Internet). Furthermore, a bitstream generated by an encoding method can be stored on a computer-readable recording medium or transmitted over a wired wireless network.

[0324] Furthermore, embodiments of this document can be embodied in computer program products comprising program code, and said program code can be executed on a computer according to the embodiments of this document. The said program code can be stored on a computer-readable carrier.

[0325] Figure 14 shows an example of a content streaming system to which the embodiments disclosed in this document can be applied.

[0326] As shown in Figure 14, the content streaming system to which the embodiments described in this document apply broadly includes an encoding server, a streaming server, a web server, a media storage facility, user equipment, and multimedia input devices.

[0327] The encoding server is responsible for compressing content input from multimedia input devices such as smartphones, cameras, and camcorders into digital data to generate a bitstream, and then transmitting this bitstream to the streaming server. As an alternative, if a multimedia input device such as a smartphone, camera, or camcorder directly generates the bitstream, the encoding server may be omitted.

[0328] The bitstream can be generated by an encoding method or bitstream generation method to which an embodiment of this document applies, and the streaming server can temporarily store the bitstream in the process of transmitting or receiving the bitstream.

[0329] The streaming server transmits multimedia data to user devices based on user requests via a web server, and the web server acts as an intermediary to inform users about available services. When a user requests a desired service from the web server, the web server transmits this to the streaming server, and the streaming server transmits multimedia data to the user. In this case, the content streaming system may include a separate control server, in which case the control server controls the commands and responses between the devices within the content streaming system.

[0330] The streaming server can receive content from a media storage and / or encoding server. For example, if it begins receiving content from the encoding server, it can receive the content in real time. In this case, in order to provide a smooth streaming service, the streaming server can store the bitstream for a certain period of time.

[0331] Examples of user devices include mobile phones, smartphones, laptop computers, digital broadcasting terminals, PDAs (personal digital assistants), PMPs (portable multimedia players), navigation systems, slate PCs, tablet PCs, ultrabooks, wearable devices (such as smartwatches, smart glasses, and HMDs), digital TVs, desktop computers, and digital signage.

[0332] Each server within the aforementioned content streaming system can be operated as a distributed server, in which case the data received by each server can be processed in a distributed manner.

Claims

1. In a decoding method performed by a decoding device, The steps include determining the prediction mode of the current block based on information about the prediction mode obtained from the bitstream, The steps include: constructing a merge candidate list based on the aforementioned prediction mode, The steps include: deriving the movement information of the current block based on the merge candidate list; The step of generating a predicted sample of the current block based on the motion information is included, The aforementioned bitstream is A CIIP availability flag indicating whether CIIP (combined inter-picture merge and intra-picture prediction) is available, A general merge flag indicating whether the interpretation parameters for the current block are derived from adjacent interpretation-predicted partitions, Includes a skip flag indicating whether the skip mode applies to the current block, The aforementioned decision-making step is: The following conditions, namely, The value of the aforementioned CIIP availability flag is equal to 1. The value of the aforementioned general merge flag is equal to 1. The value of the aforementioned skip flag is equal to 0. The product of the height of the current block and the width of the current block is 64 or more. The aforementioned height of the current block is less than 128, and The width of the aforementioned block is less than 128. A step of obtaining a regular merge flag from the bitstream based on the fact that all of the following are true, wherein the regular merge flag indicates whether the merge mode is applied to the current block, A method comprising the step of determining the regular merge mode as the prediction mode for the current block based on the value of the regular merge flag being equal to 1.

2. In an encoding method performed by an encoding device, The current block prediction mode is determined to be the regular merge mode, The steps include: constructing a merge candidate list based on the aforementioned prediction mode, The steps include: deriving the movement information of the current block based on the merge candidate list; The steps include: deriving a predicted sample of the current block based on the motion information; The steps include: deriving a residual sample based on the predicted sample; The step of encoding video information including information about the prediction mode generated based on the prediction mode and residual information generated based on the residual sample, The aforementioned video information is A CIIP availability flag indicating whether CIIP (combined inter-picture merge and intra-picture prediction) is available, A general merge flag indicating whether the interpretation parameters for the current block are derived from adjacent interpretation-predicted partitions, Includes a skip flag indicating whether the skip mode applies to the current block, The aforementioned video information is subject to the following conditions, namely: The value of the aforementioned CIIP availability flag is equal to 1. The value of the aforementioned general merge flag is equal to 1. The value of the aforementioned skip flag is equal to 0. The product of the height of the current block and the width of the current block is 64 or more. The aforementioned height of the current block is less than 128, and The width of the aforementioned block is less than 128. Based on the fact that all of the above are true, include a regular merge flag, which indicates whether the merge mode applies to the current block. A method indicating that the value of the regular merge flag is equal to 1, which determines that the regular merge mode is the predictive mode of the current block.

3. Regarding methods for transmitting video data, A step of obtaining a bitstream relating to the video, wherein the bitstream is The current block prediction mode is determined to be the regular merge mode, The steps include: constructing a merge candidate list based on the aforementioned prediction mode, The steps include: deriving the movement information of the current block based on the merge candidate list; The steps include: deriving a predicted sample of the current block based on the motion information; The steps include: deriving a residual sample based on the predicted sample; A step of generating a bitstream by encoding video information including information about the prediction mode generated based on the prediction mode and information about the residual sample generated based on the residual sample, The step of transmitting the data, which includes the bitstream, The aforementioned video information is A CIIP availability flag indicating whether CIIP (combined inter-picture merge and intra-picture prediction) is available, A general merge flag indicating whether the interpretation parameters for the current block are derived from adjacent interpretation-predicted partitions, Includes a skip flag indicating whether the skip mode applies to the current block, The aforementioned video information is subject to the following conditions, namely: The value of the aforementioned CIIP availability flag is equal to 1. The value of the aforementioned general merge flag is equal to 1. The value of the aforementioned skip flag is equal to 0. The product of the height of the current block and the width of the current block is 64 or more. The aforementioned height of the current block is less than 128, and The width of the aforementioned block is less than 128. Based on the fact that all of the above are true, include a regular merge flag, which indicates whether the merge mode applies to the current block. A transmission method in which the value of the regular merge flag being equal to 1 indicates that the regular merge mode is determined to be the predictive mode of the current block.

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