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WO2020184990A1 - Procédé et appareil de codage/décodage d'images utilisant la prédiction ibc, et procédé de transmission d'un flux binaire - Google Patents

Procédé et appareil de codage/décodage d'images utilisant la prédiction ibc, et procédé de transmission d'un flux binaire Download PDF

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WO2020184990A1
WO2020184990A1 PCT/KR2020/003409 KR2020003409W WO2020184990A1 WO 2020184990 A1 WO2020184990 A1 WO 2020184990A1 KR 2020003409 W KR2020003409 W KR 2020003409W WO 2020184990 A1 WO2020184990 A1 WO 2020184990A1
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motion vector
current block
block
prediction
candidate
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English (en)
Korean (ko)
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장형문
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LG Electronics Inc
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LG Electronics Inc
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
    • H04N19/102—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the element, parameter or selection affected or controlled by the adaptive coding
    • H04N19/103—Selection of coding mode or of prediction mode
    • H04N19/105—Selection of the reference unit for prediction within a chosen coding or prediction mode, e.g. adaptive choice of position and number of pixels used for prediction
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
    • H04N19/102—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the element, parameter or selection affected or controlled by the adaptive coding
    • H04N19/103—Selection of coding mode or of prediction mode
    • H04N19/11—Selection of coding mode or of prediction mode among a plurality of spatial predictive coding modes
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
    • H04N19/134—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the element, parameter or criterion affecting or controlling the adaptive coding
    • H04N19/136—Incoming video signal characteristics or properties
    • H04N19/137—Motion inside a coding unit, e.g. average field, frame or block difference
    • H04N19/139—Analysis of motion vectors, e.g. their magnitude, direction, variance or reliability
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
    • H04N19/169—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding
    • H04N19/17—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding the unit being an image region, e.g. an object
    • H04N19/176—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding the unit being an image region, e.g. an object the region being a block, e.g. a macroblock
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/50—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using predictive coding
    • H04N19/593—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using predictive coding involving spatial prediction techniques

Definitions

  • the present disclosure relates to an image encoding/decoding method and apparatus, and more particularly, a method and apparatus for encoding/decoding an image using IBC prediction, and transmitting a bitstream generated by the image encoding method/apparatus of the present disclosure. It's about how to do it.
  • An object of the present disclosure is to provide an image encoding/decoding method and apparatus with improved encoding/decoding efficiency.
  • an object of the present disclosure is to provide a method and apparatus for encoding/decoding an image using IBC prediction.
  • the present disclosure is to provide an image encoding/decoding method and apparatus for performing IBC prediction by using a block of a reconstructed region as a prediction block when a prediction block overlaps a current block and thus cannot be used as a prediction block during IBC prediction. The purpose.
  • an object of the present disclosure is to provide a method for transmitting a bitstream generated by an image encoding method or apparatus according to the present disclosure.
  • an object of the present disclosure is to provide a recording medium storing a bitstream generated by an image encoding method or apparatus according to the present disclosure.
  • an object of the present disclosure is to provide a recording medium storing a bitstream that is received and decoded by an image decoding apparatus according to the present disclosure and used for image restoration.
  • An image decoding method includes an image decoding method performed by an image decoding apparatus, comprising: determining a prediction mode of the current block based on prediction mode information of the current block obtained from a bitstream; When the prediction mode of the current block is an intra block copy (IBC) mode, determining a motion vector of the current block based on a motion vector candidate derived from a neighboring block of the current block; Determining a prediction block of the current block based on the motion vector; And generating a reconstructed block of the current block by using the prediction block.
  • the motion vector of the current block may be determined based on the motion vector candidate and information on the size of the current block.
  • the motion vector of the current block may be determined based on an x component of the motion vector candidate, a y component of the motion vector candidate, a width of the current block, and a height of the current block.
  • the determining of the motion vector of the current block may include, if the absolute value of the x component of the motion vector candidate is less than the width of the current block, and the absolute value of the y component of the motion vector candidate is less than the height of the current block, the Modifying the motion vector candidate; And determining a motion vector of the current block based on the modified motion vector candidate.
  • the step of modifying the motion vector candidate may be performed based on at least one of a height and a width of the current block.
  • the step of modifying the motion vector candidate is performed by replacing the absolute value of the x component of the motion vector candidate with a predetermined value equal to or greater than the width of the current block, or the absolute value of the y component of the motion vector candidate is the current block.
  • the absolute value of the x component of the motion vector candidate is replaced with a predetermined value equal to or greater than the width of the current block, and the absolute value of the y component of the motion vector candidate is the height of the current block. This can be done by substituting the above predetermined values.
  • the step of modifying the motion vector candidate is performed by applying the same scaling factor to the x component and the y component of the motion vector candidate, and the scaling factor is an absolute value of the x component of the modified motion vector candidate. It may be set to have a value equal to or greater than the width of the current block or an absolute value of the y component of the modified motion vector candidate equal to or greater than the height of the current block.
  • the sum of the upper left x coordinate of the candidate reference block indicated by the motion vector candidate and the width of the current block is greater than the upper left x coordinate of the current block, and the If the sum of the upper left y-coordinate of the candidate reference block and the height of the current block is greater than the upper-left y-coordinate of the current block, modifying the motion vector candidate; And determining a motion vector of the current block based on the modified motion vector candidate.
  • the determining of the motion vector of the current block may include constructing a motion vector candidate list using the motion vector candidate; And for each of the motion vector candidates included in the motion vector candidate list, modifying the motion vector candidate based on information about the motion vector candidate and the size of the current block.
  • the determining of the motion vector of the current block may include: modifying the motion vector candidate based on information on the motion vector candidate and the size of the current block; Constructing a motion vector candidate list using the modified motion vector candidate; And determining a motion vector of the current block based on the motion vector candidate list.
  • the modified motion vector candidate may be included in the motion vector candidate list.
  • an image decoding apparatus including a memory and at least one processor, wherein the at least one processor includes the current block based on prediction mode information of the current block obtained from a bitstream.
  • a prediction mode of is determined, and when the prediction mode of the current block is an Intra Block Copy (IBC) mode, a motion vector of the current block is determined based on a motion vector candidate derived from a neighboring block of the current block, and the A prediction block of the current block is determined based on a motion vector, and a reconstructed block of the current block is generated using the prediction block, wherein the motion vector of the current block is the motion vector candidate and the size of the current block. It can be determined based on information.
  • IBC Intra Block Copy
  • an image encoding method performed by an image encoding apparatus may include selecting a prediction mode of a current block; When the prediction mode of the current block is an Inter Block Copy (IBC) mode, generating a motion vector of the current block and a prediction block of the current block; And encoding the current block based on the prediction block, and encoding a motion vector of the current block based on a motion vector candidate derived from a neighboring block of the current block, wherein the motion vector of the current block is It may be encoded based on the motion vector candidate and information on the size of the current block.
  • IBC Inter Block Copy
  • a transmission method may transmit a bitstream generated by the image encoding apparatus or image encoding method of the present disclosure.
  • a computer-readable recording medium may store a bitstream generated by the image encoding method or image encoding apparatus of the present disclosure.
  • an image encoding/decoding method and apparatus with improved encoding/decoding efficiency may be provided.
  • a method and apparatus for encoding/decoding an image by using a block of a reconstructed region as a prediction block when a prediction block overlaps a current block and cannot be used as a prediction block during IBC prediction can be provided.
  • a method for transmitting a bitstream generated by an image encoding method or apparatus according to the present disclosure may be provided.
  • a recording medium storing a bitstream generated by an image encoding method or apparatus according to the present disclosure may be provided.
  • a recording medium may be provided that stores a bitstream that is received and decoded by the image decoding apparatus according to the present disclosure and used for image restoration.
  • FIG. 1 is a diagram schematically illustrating a video coding system to which an embodiment according to the present disclosure can be applied.
  • FIG. 2 is a diagram schematically illustrating an image encoding apparatus to which an embodiment according to the present disclosure can be applied.
  • FIG. 3 is a diagram schematically illustrating an image decoding apparatus to which an embodiment according to the present disclosure can be applied.
  • FIG. 4 is a diagram showing a block division type according to a multi-type tree structure.
  • FIG. 5 is a diagram illustrating a signaling mechanism of partitioning information of a quadtree with nested multi-type tree structure according to the present disclosure.
  • FIG. 6 is a flowchart illustrating a video/video encoding method based on inter prediction.
  • FIG. 7 is a diagram illustrating a configuration of an inter prediction unit 180 according to the present disclosure.
  • FIG. 8 is a flowchart illustrating a video/video decoding method based on inter prediction.
  • FIG. 9 is a diagram illustrating an exemplary configuration of an inter prediction unit 260 according to the present disclosure.
  • FIG. 10 is a diagram illustrating neighboring blocks that can be used as spatial merge candidates.
  • FIG. 11 is a diagram schematically illustrating a method of constructing a merge candidate list according to an example of the present disclosure.
  • FIG. 12 is a diagram schematically illustrating a method of constructing a motion vector predictor candidate list according to an example of the present disclosure.
  • FIG. 13 is a diagram illustrating a syntax structure for transmitting MVD from an image encoding device to an image decoding device according to an example of the present disclosure.
  • FIG. 14 is a flowchart illustrating an IBC-based video/video encoding method.
  • 15 is a diagram illustrating a configuration of a prediction unit that performs an IBC-based video/video encoding method according to the present disclosure.
  • 16 is a flowchart illustrating an IBC-based video/video decoding method.
  • 17 is a diagram illustrating a configuration of a prediction unit that performs an IBC-based video/video decoding method according to the present disclosure.
  • 18 is a diagram illustrating an example of a current block and a candidate reference block, which are decoding target blocks.
  • FIG. 19 is a diagram illustrating an embodiment in which a motion vector candidate of a current block is modified.
  • FIG. 20 is a diagram illustrating a method of performing decoding by updating a candidate reference block by a decoding apparatus according to an embodiment.
  • 21 is a flowchart illustrating a method of determining availability of a candidate reference block by comparing a lower right position of a candidate reference block and an upper left position of a current block, by a decoding apparatus according to an embodiment.
  • FIG. 22 is a flowchart illustrating a method of determining the availability of a candidate reference block based on information about a motion vector candidate and a size of a current block, by a decoding apparatus according to an embodiment.
  • FIG. 23 is a diagram illustrating an embodiment of updating a candidate reference block in a horizontal direction.
  • 24 is a diagram illustrating an embodiment of updating a candidate reference block in a vertical direction.
  • 25 is a diagram illustrating an embodiment of updating a candidate reference block in a diagonal direction.
  • 26 and 27 are diagrams for explaining an embodiment of updating a candidate reference block in a direction indicated by a motion vector candidate.
  • 28 is a diagram illustrating an embodiment of performing decoding by applying an update of a motion vector candidate.
  • 29 is a flowchart illustrating a method of constructing a motion vector candidate list by determining availability of a motion vector candidate by a decoding apparatus according to an embodiment.
  • FIG. 30 is a flowchart illustrating a method of updating a motion vector candidate list by determining availability of a motion vector candidate included in the motion vector candidate list by the decoding apparatus according to an embodiment.
  • FIG. 31 is a diagram illustrating a method of encoding an image using updating of a candidate reference block or a motion vector candidate by an encoding apparatus according to an embodiment.
  • FIG. 32 is a diagram illustrating a content streaming system to which an embodiment of the present disclosure can be applied.
  • first and second are used only for the purpose of distinguishing one component from other components, and do not limit the order or importance of the components unless otherwise stated. Accordingly, within the scope of the present disclosure, a first component in one embodiment may be referred to as a second component in another embodiment, and similarly, a second component in one embodiment is a first component in another embodiment. It can also be called.
  • components that are distinguished from each other are intended to clearly describe each feature, and do not necessarily mean that the components are separated. That is, a plurality of components may be integrated to be formed in one hardware or software unit, or one component may be distributed in a plurality of hardware or software units. Therefore, even if not stated otherwise, such integrated or distributed embodiments are also included in the scope of the present disclosure.
  • the components described in various embodiments do not necessarily mean essential components, and some may be optional components. Accordingly, an embodiment consisting of a subset of components described in an embodiment is also included in the scope of the present disclosure. In addition, embodiments including other elements in addition to the elements described in the various embodiments are included in the scope of the present disclosure.
  • the present disclosure relates to encoding and decoding of an image, and terms used in the present disclosure may have a common meaning commonly used in the technical field to which the present disclosure belongs unless newly defined in the present disclosure.
  • a “picture” generally refers to a unit representing one image in a specific time period
  • a slice/tile is a coding unit constituting a part of a picture
  • one picture is one It may be composed of more than one slice/tile.
  • a slice/tile may include one or more coding tree units (CTU).
  • pixel or "pel” may mean a minimum unit constituting one picture (or image).
  • sample may be used as a term corresponding to a pixel.
  • a sample may generally represent a pixel or a value of a pixel, may represent only a pixel/pixel value of a luma component, or may represent only a pixel/pixel value of a chroma component.
  • unit may represent a basic unit of image processing.
  • the unit may include at least one of a specific area of a picture and information related to the corresponding area.
  • the unit may be used interchangeably with terms such as “sample array”, “block”, or “area” depending on the case.
  • the MxN block may include samples (or sample arrays) consisting of M columns and N rows, or a set (or array) of transform coefficients.
  • current block may mean one of “current coding block”, “current coding unit”, “coding object block”, “decoding object block”, or “processing object block”.
  • current block may mean “current prediction block” or “prediction target block”.
  • transformation inverse transformation
  • quantization inverse quantization
  • current block may mean “current transform block” or “transform target block”.
  • filtering is performed, “current block” may mean “block to be filtered”.
  • current block may mean “a luma block of the current block” unless explicitly stated as a chroma block.
  • the "chroma block of the current block” may be expressed by including an explicit description of a chroma block, such as “chroma block” or "current chroma block”.
  • FIG. 1 shows a video coding system according to this disclosure.
  • a video coding system may include an encoding device 10 and a decoding device 20.
  • the encoding device 10 may transmit the encoded video and/or image information or data in a file or streaming format to the decoding device 20 through a digital storage medium or a network.
  • the encoding apparatus 10 may include a video source generator 11, an encoder 12, and a transmission unit 13.
  • the decoding apparatus 20 may include a receiving unit 21, a decoding unit 22, and a rendering unit 23.
  • the encoder 12 may be referred to as a video/image encoder, and the decoder 22 may be referred to as a video/image decoder.
  • the transmission unit 13 may be included in the encoding unit 12.
  • the receiving unit 21 may be included in the decoding unit 22.
  • the rendering unit 23 may include a display unit, and the display unit may be configured as a separate device or an external component.
  • the video source generator 11 may acquire a video/image through a process of capturing, synthesizing, or generating a video/image.
  • the video source generator 11 may include a video/image capturing device and/or a video/image generating device.
  • the video/image capture device may include, for example, one or more cameras, a video/image archive including previously captured video/images, and the like.
  • the video/image generating device may include, for example, a computer, a tablet and a smartphone, and may (electronically) generate a video/image.
  • a virtual video/image may be generated through a computer or the like, and in this case, a video/image capturing process may be substituted as a process of generating related data.
  • the encoder 12 may encode an input video/image.
  • the encoder 12 may perform a series of procedures such as prediction, transformation, and quantization for compression and encoding efficiency.
  • the encoder 12 may output encoded data (coded video/image information) in a bitstream format.
  • the transmission unit 13 may transmit the encoded video/image information or data output in the form of a bitstream to the receiving unit 21 of the decoding apparatus 20 through a digital storage medium or a network in a file or streaming form.
  • Digital storage media may include various storage media such as USB, SD, CD, DVD, Blu-ray, HDD, and SSD.
  • the transmission unit 13 may include an element for generating a media file through a predetermined file format, and may include an element for transmission through a broadcast/communication network.
  • the receiving unit 21 may extract/receive the bitstream from the storage medium or network and transmit it to the decoding unit 22.
  • the decoder 22 may decode the video/image by performing a series of procedures such as inverse quantization, inverse transformation, and prediction corresponding to the operation of the encoder 12.
  • the rendering unit 23 may render the decoded video/image.
  • the rendered video/image may be displayed through the display unit.
  • FIG. 2 is a diagram schematically illustrating an image encoding apparatus to which an embodiment according to the present disclosure can be applied.
  • the image encoding apparatus 100 includes an image segmentation unit 110, a subtraction unit 115, a transform unit 120, a quantization unit 130, an inverse quantization unit 140, and an inverse transform unit ( 150), an addition unit 155, a filtering unit 160, a memory 170, an inter prediction unit 180, an intra prediction unit 185, and an entropy encoding unit 190.
  • the inter prediction unit 180 and the intra prediction unit 185 may be collectively referred to as a “prediction unit”.
  • the transform unit 120, the quantization unit 130, the inverse quantization unit 140, and the inverse transform unit 150 may be included in a residual processing unit.
  • the residual processing unit may further include a subtraction unit 115.
  • All or at least some of the plurality of constituent units constituting the image encoding apparatus 100 may be implemented as one hardware component (eg, an encoder or a processor) according to embodiments.
  • the memory 170 may include a decoded picture buffer (DPB), and may be implemented by a digital storage medium.
  • DPB decoded picture buffer
  • the image dividing unit 110 may divide an input image (or picture, frame) input to the image encoding apparatus 100 into one or more processing units.
  • the processing unit may be referred to as a coding unit (CU).
  • the coding unit is a coding tree unit (CTU) or a largest coding unit (LCU) recursively according to a QT/BT/TT (Quad-tree/binary-tree/ternary-tree) structure ( It can be obtained by dividing recursively.
  • one coding unit may be divided into a plurality of coding units of a deeper depth based on a quad tree structure, a binary tree structure, and/or a ternary tree structure.
  • a quad tree structure may be applied first, and a binary tree structure and/or a ternary tree structure may be applied later.
  • the coding procedure according to the present disclosure may be performed based on the final coding unit that is no longer divided.
  • the largest coding unit may be directly used as the final coding unit, or a coding unit of a lower depth obtained by dividing the largest coding unit may be used as the final cornet unit.
  • the coding procedure may include a procedure such as prediction, transformation, and/or restoration described later.
  • the processing unit of the coding procedure may be a prediction unit (PU) or a transform unit (TU).
  • Each of the prediction unit and the transform unit may be divided or partitioned from the final coding unit.
  • the prediction unit may be a unit of sample prediction
  • the transform unit may be a unit for inducing a transform coefficient and/or a unit for inducing a residual signal from the transform coefficient.
  • the prediction unit (inter prediction unit 180 or intra prediction unit 185) performs prediction on a block to be processed (current block), and generates a predicted block including prediction samples for the current block. Can be generated.
  • the prediction unit may determine whether intra prediction or inter prediction is applied in units of the current block or CU.
  • the prediction unit may generate various information on prediction of the current block and transmit it to the entropy encoding unit 190.
  • the information on prediction may be encoded by the entropy encoding unit 190 and output in the form of a bitstream.
  • the intra prediction unit 185 may predict the current block by referring to samples in the current picture.
  • the referenced samples may be located in a neighborhood of the current block or may be located away from each other according to an intra prediction mode and/or an intra prediction technique.
  • the intra prediction modes may include a plurality of non-directional modes and a plurality of directional modes.
  • the non-directional mode may include, for example, a DC mode and a planar mode (Planar mode).
  • the directional mode may include, for example, 33 directional prediction modes or 65 directional prediction modes, depending on the degree of detail of the prediction direction. However, this is an example, and more or less directional prediction modes may be used depending on the setting.
  • the intra prediction unit 185 may determine a prediction mode applied to the current block by using the prediction mode applied to the neighboring block.
  • the inter prediction unit 180 may derive a predicted block for the current block based on a reference block (reference sample array) specified by a motion vector on the reference picture.
  • motion information may be predicted in units of blocks, subblocks, or samples based on a correlation between motion information between a neighboring block and a current block.
  • the motion information may include a motion vector and a reference picture index.
  • the motion information may further include inter prediction direction (L0 prediction, L1 prediction, Bi prediction, etc.) information.
  • the neighboring block may include a spatial neighboring block existing in the current picture and a temporal neighboring block existing in the reference picture.
  • the reference picture including the reference block and the reference picture including the temporal neighboring block may be the same or different from each other.
  • the temporal neighboring block may be referred to as a collocated reference block, a collocated CU (colCU), or the like.
  • a reference picture including the temporal neighboring block may be referred to as a collocated picture (colPic).
  • the inter prediction unit 180 constructs a motion information candidate list based on neighboring blocks, and provides information indicating which candidate is used to derive a motion vector and/or a reference picture index of the current block. Can be generated. Inter prediction may be performed based on various prediction modes.
  • the inter prediction unit 180 may use motion information of a neighboring block as motion information of a current block.
  • a residual signal may not be transmitted.
  • motion vector prediction (MVP) mode motion vectors of neighboring blocks are used as motion vector predictors, and indicators for motion vector difference and motion vector predictors ( indicator) to signal the motion vector of the current block.
  • the motion vector difference may mean a difference between a motion vector of a current block and a motion vector predictor.
  • the prediction unit may generate a prediction signal based on various prediction methods and/or prediction techniques to be described later. For example, the prediction unit may apply intra prediction or inter prediction for prediction of the current block, and may simultaneously apply intra prediction and inter prediction. A prediction method in which intra prediction and inter prediction are applied simultaneously for prediction of a current block may be called combined inter and intra prediction (CIIP). Also, the prediction unit may perform intra block copy (IBC) for prediction of the current block. The intra block copy may be used for content image/movie coding such as games, such as, for example, screen content coding (SCC). IBC is a method of predicting a current block by using a reference block in a current picture at a distance from the current block by a predetermined distance.
  • CIIP combined inter and intra prediction
  • IBC intra block copy
  • the intra block copy may be used for content image/movie coding such as games, such as, for example, screen content coding (SCC).
  • IBC is a method of predicting a current block by using a reference
  • the position of the reference block in the current picture may be encoded as a vector (block vector) corresponding to the predetermined distance.
  • IBC basically performs prediction in the current picture, but may be performed similarly to inter prediction in that it derives a reference block in the current picture. That is, the IBC may use at least one of the inter prediction techniques described in this disclosure.
  • the prediction signal generated through the prediction unit may be used to generate a reconstructed signal or may be used to generate a residual signal.
  • the subtraction unit 115 subtracts the prediction signal (predicted block, prediction sample array) output from the prediction unit from the input image signal (original block, original sample array), and subtracts a residual signal (remaining block, residual sample array). ) Can be created.
  • the generated residual signal may be transmitted to the converter 120.
  • the transform unit 120 may generate transform coefficients by applying a transform technique to the residual signal.
  • the transformation technique uses at least one of DCT (Discrete Cosine Transform), DST (Discrete Sine Transform), KLT (Karhunen-Loeve Transform), GBT (Graph-Based Transform), or CNT (Conditionally Non-linear Transform).
  • DCT Discrete Cosine Transform
  • DST Discrete Sine Transform
  • KLT Kerhunen-Loeve Transform
  • GBT Graph-Based Transform
  • CNT Conditionally Non-linear Transform
  • GBT refers to the transformation obtained from this graph when the relationship information between pixels is expressed in a graph.
  • CNT refers to a transformation obtained based on generating a prediction signal using all previously reconstructed pixels.
  • the conversion process may be applied to a block of pixels having the same size of a square, or may be applied to a block of a variable size other than a square.
  • the quantization unit 130 may quantize the transform coefficients and transmit the quantization to the entropy encoding unit 190.
  • the entropy encoding unit 190 may encode a quantized signal (information on quantized transform coefficients) and output it as a bitstream.
  • the information on the quantized transform coefficients may be called residual information.
  • the quantization unit 130 may rearrange the quantized transform coefficients in the form of a block into a one-dimensional vector form based on a coefficient scan order, and the quantized transform coefficients in the form of the one-dimensional vector It is also possible to generate information about transform coefficients.
  • the entropy encoding unit 190 may perform various encoding methods such as exponential Golomb, context-adaptive variable length coding (CAVLC), and context-adaptive binary arithmetic coding (CABAC).
  • the entropy encoding unit 190 may encode together or separately information necessary for video/image restoration (eg, values of syntax elements) in addition to quantized transform coefficients.
  • the encoded information (eg, encoded video/video information) may be transmitted or stored in a bitstream format in units of network abstraction layer (NAL) units.
  • the video/video information may further include information on various parameter sets, such as an adaptation parameter set (APS), a picture parameter set (PPS), a sequence parameter set (SPS), or a video parameter set (VPS).
  • the video/video information may further include general constraint information.
  • the signaling information, transmitted information, and/or syntax elements mentioned in the present disclosure may be encoded through the above-described encoding procedure and included in the bitstream.
  • the bitstream may be transmitted through a network or may be stored in a digital storage medium.
  • the network may include a broadcasting network and/or a communication network
  • the digital storage medium may include various storage media such as USB, SD, CD, DVD, Blu-ray, HDD, and SSD.
  • a transmission unit (not shown) for transmitting the signal output from the entropy encoding unit 190 and/or a storage unit (not shown) for storing may be provided as an inner/outer element of the image encoding apparatus 100, or transmission The unit may be provided as a component of the entropy encoding unit 190.
  • the quantized transform coefficients output from the quantization unit 130 may be used to generate a residual signal.
  • a residual signal residual block or residual samples
  • inverse quantization and inverse transform residual transforms
  • the addition unit 155 adds the reconstructed residual signal to the prediction signal output from the inter prediction unit 180 or the intra prediction unit 185 to obtain a reconstructed signal (a reconstructed picture, a reconstructed block, and a reconstructed sample array). Can be generated.
  • a reconstructed signal (a reconstructed picture, a reconstructed block, and a reconstructed sample array).
  • the predicted block may be used as a reconstructed block.
  • the addition unit 155 may be referred to as a restoration unit or a restoration block generation unit.
  • the generated reconstructed signal may be used for intra prediction of the next processing target block in the current picture, and may be used for inter prediction of the next picture through filtering as described later.
  • the filtering unit 160 may apply filtering to the reconstructed signal to improve subjective/objective image quality.
  • the filtering unit 160 may generate a modified reconstructed picture by applying various filtering methods to the reconstructed picture, and the modified reconstructed picture may be converted to the memory 170, specifically, the DPB of the memory 170. Can be saved on.
  • the various filtering methods may include, for example, deblocking filtering, sample adaptive offset, adaptive loop filter, bilateral filter, and the like.
  • the filtering unit 160 may generate a variety of filtering information and transmit it to the entropy encoding unit 190 as described later in the description of each filtering method.
  • the filtering information may be encoded by the entropy encoding unit 190 and output in the form of a bitstream.
  • the modified reconstructed picture transmitted to the memory 170 may be used as a reference picture in the inter prediction unit 180.
  • the image encoding apparatus 100 may avoid prediction mismatch between the image encoding apparatus 100 and the image decoding apparatus, and may improve encoding efficiency.
  • the DPB in the memory 170 may store a reconstructed picture modified to be used as a reference picture in the inter prediction unit 180.
  • the memory 170 may store motion information of a block from which motion information in a current picture is derived (or encoded) and/or motion information of blocks in a picture that have already been reconstructed.
  • the stored motion information may be transmitted to the inter prediction unit 180 to be used as motion information of spatial neighboring blocks or motion information of temporal neighboring blocks.
  • the memory 170 may store reconstructed samples of reconstructed blocks in the current picture, and may transmit the reconstructed samples to the intra prediction unit 185.
  • FIG. 3 is a diagram schematically illustrating an image decoding apparatus to which an embodiment according to the present disclosure can be applied.
  • the image decoding apparatus 200 includes an entropy decoding unit 210, an inverse quantization unit 220, an inverse transform unit 230, an addition unit 235, a filtering unit 240, and a memory 250. ), an inter prediction unit 260 and an intra prediction unit 265 may be included.
  • the inter prediction unit 260 and the intra prediction unit 265 may be collectively referred to as a “prediction unit”.
  • the inverse quantization unit 220 and the inverse transform unit 230 may be included in the residual processing unit.
  • All or at least some of the plurality of constituent units constituting the image decoding apparatus 200 may be implemented as one hardware component (eg, a decoder or a processor) according to embodiments.
  • the memory 170 may include a DPB and may be implemented by a digital storage medium.
  • the image decoding apparatus 200 having received a bitstream including video/image information may reconstruct an image by performing a process corresponding to the process performed by the image encoding apparatus 100 of FIG. 2.
  • the image decoding apparatus 200 may perform decoding using a processing unit applied in the image encoding apparatus.
  • the processing unit of decoding may be, for example, a coding unit.
  • the coding unit may be a coding tree unit or may be obtained by dividing the largest coding unit.
  • the reconstructed image signal decoded and output through the image decoding apparatus 200 may be reproduced through a reproduction device (not shown).
  • the image decoding apparatus 200 may receive a signal output from the image encoding apparatus of FIG. 2 in the form of a bitstream.
  • the received signal may be decoded through the entropy decoding unit 210.
  • the entropy decoding unit 210 may parse the bitstream to derive information (eg, video/video information) necessary for image restoration (or picture restoration).
  • the video/video information may further include information on various parameter sets, such as an adaptation parameter set (APS), a picture parameter set (PPS), a sequence parameter set (SPS), or a video parameter set (VPS).
  • the video/video information may further include general constraint information.
  • the image decoding apparatus may additionally use information on the parameter set and/or the general restriction information to decode an image.
  • the signaling information, received information and/or syntax elements mentioned in the present disclosure may be obtained from the bitstream by being decoded through the decoding procedure.
  • the entropy decoding unit 210 decodes information in the bitstream based on a coding method such as exponential Golomb coding, CAVLC, or CABAC, and a value of a syntax element required for image restoration, a quantized value of a transform coefficient related to a residual. Can be printed.
  • the CABAC entropy decoding method receives a bin corresponding to each syntax element in a bitstream, and includes information on the syntax element to be decoded, information on decoding information of a neighboring block and a block to be decoded, or information on a symbol/bin decoded in a previous step
  • the context model is determined by using and, according to the determined context model, the probability of occurrence of bins is predicted to perform arithmetic decoding of bins to generate symbols corresponding to the values of each syntax element. I can.
  • the CABAC entropy decoding method may update the context model using information of the decoded symbol/bin for the context model of the next symbol/bin after the context model is determined.
  • the entropy decoding unit 210 Among the information decoded by the entropy decoding unit 210, information on prediction is provided to the prediction unit (inter prediction unit 260 and intra prediction unit 265), and the register on which entropy decoding is performed by the entropy decoding unit 210 Dual values, that is, quantized transform coefficients and related parameter information may be input to the inverse quantization unit 220. In addition, information about filtering among information decoded by the entropy decoding unit 210 may be provided to the filtering unit 240.
  • a receiving unit for receiving a signal output from the image encoding device may be additionally provided as an inner/outer element of the image decoding device 200, or the receiving unit is provided as a component of the entropy decoding unit 210 It could be.
  • the video decoding apparatus may include an information decoder (video/video/picture information decoder) and/or a sample decoder (video/video/picture sample decoder).
  • the information decoder may include an entropy decoding unit 210, and the sample decoder includes an inverse quantization unit 220, an inverse transform unit 230, an addition unit 235, a filtering unit 240, a memory 250, It may include at least one of the inter prediction unit 260 and the intra prediction unit 265.
  • the inverse quantization unit 220 may inverse quantize the quantized transform coefficients and output transform coefficients.
  • the inverse quantization unit 220 may rearrange the quantized transform coefficients into a two-dimensional block shape. In this case, the rearrangement may be performed based on a coefficient scan order performed by the image encoding apparatus.
  • the inverse quantization unit 220 may perform inverse quantization on quantized transform coefficients by using a quantization parameter (eg, quantization step size information) and obtain transform coefficients.
  • a quantization parameter eg, quantization step size information
  • the inverse transform unit 230 may inversely transform transform coefficients to obtain a residual signal (residual block, residual sample array).
  • the prediction unit may perform prediction on the current block and generate a predicted block including prediction samples for the current block.
  • the prediction unit may determine whether intra prediction or inter prediction is applied to the current block based on the prediction information output from the entropy decoding unit 210, and determine a specific intra/inter prediction mode (prediction technique). I can.
  • the prediction unit can generate the prediction signal based on various prediction methods (techniques) described later.
  • the intra prediction unit 265 may predict the current block by referring to samples in the current picture.
  • the description of the intra prediction unit 185 may be equally applied to the intra prediction unit 265.
  • the inter prediction unit 260 may derive a predicted block for the current block based on a reference block (reference sample array) specified by a motion vector on the reference picture.
  • motion information may be predicted in units of blocks, subblocks, or samples based on a correlation between motion information between a neighboring block and a current block.
  • the motion information may include a motion vector and a reference picture index.
  • the motion information may further include inter prediction direction (L0 prediction, L1 prediction, Bi prediction, etc.) information.
  • the neighboring block may include a spatial neighboring block existing in the current picture and a temporal neighboring block existing in the reference picture.
  • the inter prediction unit 260 may construct a motion information candidate list based on neighboring blocks, and derive a motion vector and/or a reference picture index of the current block based on the received candidate selection information.
  • Inter prediction may be performed based on various prediction modes (techniques), and the information about the prediction may include information indicating a mode (technique) of inter prediction for the current block.
  • the addition unit 235 is reconstructed by adding the obtained residual signal to the prediction signal (predicted block, prediction sample array) output from the prediction unit (including the inter prediction unit 260 and/or the intra prediction unit 265). Signals (restored pictures, reconstructed blocks, reconstructed sample arrays) can be generated. When there is no residual for a block to be processed, such as when the skip mode is applied, the predicted block may be used as a reconstructed block.
  • the description of the addition unit 155 may be equally applied to the addition unit 235.
  • the addition unit 235 may be referred to as a restoration unit or a restoration block generation unit.
  • the generated reconstructed signal may be used for intra prediction of the next processing target block in the current picture, and may be used for inter prediction of the next picture through filtering as described later.
  • the filtering unit 240 may apply filtering to the reconstructed signal to improve subjective/objective image quality.
  • the filtering unit 240 may generate a modified reconstructed picture by applying various filtering methods to the reconstructed picture, and the modified reconstructed picture may be converted to the memory 250, specifically the DPB of the memory 250. Can be saved on.
  • the various filtering methods may include, for example, deblocking filtering, sample adaptive offset, adaptive loop filter, bilateral filter, and the like.
  • the (modified) reconstructed picture stored in the DPB of the memory 250 may be used as a reference picture in the inter prediction unit 260.
  • the memory 250 may store motion information of a block from which motion information in a current picture is derived (or decoded) and/or motion information of blocks in a picture that have already been reconstructed.
  • the stored motion information may be transmitted to the inter prediction unit 260 to be used as motion information of a spatial neighboring block or motion information of a temporal neighboring block.
  • the memory 250 may store reconstructed samples of reconstructed blocks in the current picture, and may be transmitted to the intra prediction unit 265.
  • embodiments described in the filtering unit 160, the inter prediction unit 180, and the intra prediction unit 185 of the image encoding apparatus 100 are respectively the filtering unit 240 of the image decoding apparatus 200, The same or corresponding to the inter prediction unit 260 and the intra prediction unit 265 may be applied.
  • the coding unit is obtained by recursively dividing a coding tree unit (CTU) or a maximum coding unit (LCU) according to a QT/BT/TT (Quad-tree/binary-tree/ternary-tree) structure.
  • CTU coding tree unit
  • LCU maximum coding unit
  • QT/BT/TT Quad-tree/binary-tree/ternary-tree
  • the CTU may be first divided into a quadtree structure. Thereafter, leaf nodes of a quadtree structure may be further divided by a multitype tree structure.
  • the division according to the quadtree means division in which the current CU (or CTU) is divided into four. By partitioning according to the quadtree, the current CU can be divided into four CUs having the same width and the same height.
  • the current CU corresponds to a leaf node of the quadtree structure.
  • the CU corresponding to the leaf node of the quadtree structure is no longer divided and may be used as the above-described final coding unit.
  • a CU corresponding to a leaf node of a quadtree structure may be further divided by a multitype tree structure.
  • the division according to the multi-type tree structure may include two divisions according to a binary tree structure and two divisions according to a ternary tree structure.
  • the two divisions according to the binary tree structure may include vertical binary splitting (SPLIT_BT_VER) and horizontal binary splitting (SPLIT_BT_HOR).
  • the vertical binary division (SPLIT_BT_VER) means division in which the current CU is divided into two in the vertical direction. As shown in FIG. 4, two CUs having a height equal to the height of the current CU and a width of half the width of the current CU may be generated by vertical binary division.
  • the horizontal binary division means division in which the current CU is divided into two in the horizontal direction. As shown in FIG. 4, two CUs having a height of half the height of the current CU and a width equal to the width of the current CU may be generated by horizontal binary division.
  • the two divisions according to the ternary tree structure may include vertical ternary splitting (SPLIT_TT_VER) and horizontal ternary splitting (hotizontal ternary splitting, SPLIT_TT_HOR).
  • Vertical ternary division (SPLIT_TT_VER) divides the current CU in a vertical direction at a ratio of 1:2:1. As shown in FIG. 4, by vertical ternary division, two CUs having a height equal to the height of the current CU and a width of 1/4 of the width of the current CU, and a current CU having a height equal to the height of the current CU A CU with a width of half the width of can be created.
  • the horizontal ternary division divides the current CU horizontally at a ratio of 1:2:1. As shown in FIG. 4, by horizontal ternary division, two CUs having a height of 1/4 of the height of the current CU and having the same width as the width of the current CU and a height of half the height of the current CU One CU can be created with a width equal to the width of the CU.
  • FIG. 5 is a diagram illustrating a signaling mechanism of partitioning information of a quadtree with nested multi-type tree structure according to the present disclosure.
  • the CTU is treated as the root node of a quadtree, and is first partitioned into a quadtree structure.
  • Information eg, qt_split_flag
  • qt_split_flag a first value (eg, “1”)
  • the current CU may be quadtree split.
  • qt_split_flag is a second value (eg, "0")
  • the current CU is not divided into a quadtree, but becomes a leaf node (QT_leaf_node) of the quadtree.
  • the leaf nodes of each quadtree can then be further partitioned into a multitype tree structure. That is, a leaf node of a quad tree may be a node (MTT_node) of a multi-type tree.
  • a first flag eg, mtt_split_cu_flag
  • a second flag (ex.mtt_split_cu_verticla_flag) may be signaled to indicate the splitting direction.
  • the division direction may be a vertical direction
  • the second flag is 0, the division direction may be a horizontal direction.
  • a third flag (eg, mtt_split_cu_binary_flag) may be signaled to indicate whether the division type is a binary division type or a ternary division type.
  • the division type may be a binary division type
  • the third flag when the third flag is 0, the division type may be a ternary division type.
  • Nodes of a multitype tree obtained by binary division or ternary division may be further partitioned into a multitype tree structure.
  • nodes of a multitype tree cannot be partitioned into a quadtree structure.
  • the first flag is 0, the corresponding node of the multitype tree is no longer divided and becomes a leaf node (MTT_leaf_node) of the multitype tree.
  • the CU corresponding to the leaf node of the multitype tree may be used as the above-described final coding unit.
  • a multi-type tree splitting mode (MttSplitMode) of the CU may be derived as shown in Table 1.
  • One CTU may include a coding block of luma samples (hereinafter, referred to as a “luma block”) and two coding blocks of chroma samples corresponding thereto (hereinafter referred to as a “chroma block”).
  • the above-described coding tree scheme may be applied equally to the luma block and the chroma block of the current CU, or may be applied separately.
  • a luma block and a chroma block in one CTU may be divided into the same block tree structure, and the tree structure in this case may be represented as a single tree (SINGLE_TREE).
  • a luma block and a chroma block in one CTU may be divided into individual block tree structures, and the tree structure in this case may be represented as a dual tree (DUAL_TREE). That is, when the CTU is divided into a dual tree, a block tree structure for a luma block and a block tree structure for a chroma block may exist separately.
  • the block tree structure for the luma block may be referred to as a dual tree luma (DUAL_TREE_LUMA)
  • the block tree structure for the chroma block may be referred to as a dual tree chroma (DUAL_TREE_CHROMA).
  • luma blocks and chroma blocks in one CTU may be limited to have the same coding tree structure.
  • luma blocks and chroma blocks may have separate block tree structures from each other. If an individual block tree structure is applied, a luma coding tree block (CTB) may be divided into CUs based on a specific coding tree structure, and the chroma CTB may be divided into chroma CUs based on a different coding tree structure.
  • CTB luma coding tree block
  • a CU in an I slice/tile group to which an individual block tree structure is applied is composed of a coding block of a luma component or coding blocks of two chroma components
  • a CU of a P or B slice/tile group has three color components (luma component And it may mean that it may be composed of blocks of two chroma components).
  • the structure in which the CU is divided is not limited thereto.
  • the BT structure and the TT structure may be interpreted as a concept included in the Multiple Partitioning Tree (MPT) structure, and the CU may be interpreted as being divided through the QT structure and the MPT structure.
  • MPT Multiple Partitioning Tree
  • a syntax element e.g., MPT_split_type
  • MPT_split_mode a syntax element including information on which direction of splitting between horizontal and horizontal.
  • the CU may be divided in a different way from the QT structure, BT structure, or TT structure. That is, according to the QT structure, the CU of the lower depth is divided into 1/4 size of the CU of the upper depth, or the CU of the lower depth is divided into 1/2 of the CU of the upper depth according to the BT structure, or according to the TT structure. Unlike CUs of lower depth are divided into 1/4 or 1/2 of CUs of higher depth, CUs of lower depth are 1/5, 1/3, 3/8, 3 of CUs of higher depth depending on the case. It may be divided into /5, 2/3, or 5/8 size, and the method of dividing the CU is not limited thereto.
  • the prediction unit of the video encoding apparatus/video decoding apparatus may derive a prediction sample by performing inter prediction in block units.
  • Inter prediction may represent prediction derived by a method dependent on data elements (e.g. sample values, motion information, etc.) of a picture(s) other than the current picture.
  • motion information of the current block may be predicted in units of blocks, subblocks, or samples based on correlation between motion information between neighboring blocks and the current block.
  • the motion information may include a motion vector and a reference picture index.
  • the motion information may further include inter prediction type (L0 prediction, L1 prediction, Bi prediction, etc.) information.
  • the neighboring block may include a spatial neighboring block existing in the current picture and a temporal neighboring block existing in the reference picture.
  • the reference picture including the reference block and the reference picture including the temporal neighboring block may be the same or different.
  • the temporal neighboring block may be called a collocated reference block, a collocated CU (colCU), a collocated block, and the like, and a reference picture including the temporal neighboring block is a collocated picture. It may be called by a name such as picture, colPic), or colPicture.
  • a motion information candidate list may be constructed based on neighboring blocks of the current block, and a flag indicating which candidate is selected (used) to derive a motion vector and/or a reference picture index of the current block Alternatively, index information may be signaled.
  • Inter prediction may be performed based on various prediction modes.
  • motion information of a current block may be the same as motion information of a selected neighboring block.
  • a residual signal may not be transmitted.
  • MVP motion vector prediction
  • a motion vector of a selected neighboring block is used as a motion vector predictor, and a motion vector difference may be signaled.
  • the motion vector of the current block may be derived by using the sum of the motion vector predictor and the motion vector difference.
  • the MVP mode may have the same meaning as AMVP (Advanced Motion Vector Prediction).
  • the motion information may include L0 motion information and/or L1 motion information according to an inter prediction type (L0 prediction, L1 prediction, Bi prediction, etc.).
  • the motion vector in the L0 direction may be referred to as an L0 motion vector or MVL0
  • the motion vector in the L1 direction may be referred to as an L1 motion vector or MVL1.
  • the prediction based on the L0 motion vector may be referred to as L0 prediction
  • the prediction based on the L1 motion vector may be referred to as the L1 prediction
  • the prediction based on both the L0 motion vector and the L1 motion vector may be referred to as a pair (Bi) prediction.
  • I can.
  • the motion vector L0 may represent a motion vector associated with the reference picture list L0 (L0), and the motion vector L1 may represent a motion vector associated with the reference picture list L1 (L1).
  • the reference picture list L0 may include pictures prior to the current picture in output order as reference pictures, and the reference picture list L1 may include pictures after the current picture in output order.
  • the previous pictures may be referred to as forward (reference) pictures, and the subsequent pictures may be referred to as reverse (reference) pictures.
  • the reference picture list L0 may further include pictures later in output order than the current picture as reference pictures. In this case, the previous pictures in the reference picture list L0 may be indexed first, and the subsequent pictures may be indexed next.
  • the reference picture list L1 may further include pictures preceding the current picture in an output order as reference pictures.
  • the subsequent pictures may be indexed first, and the previous pictures may be indexed next.
  • the output order may correspond to a picture order count (POC) order.
  • POC picture order count
  • FIG. 6 is a flowchart illustrating a video/video encoding method based on inter prediction.
  • FIG. 7 is a diagram illustrating a configuration of an inter prediction unit 180 according to the present disclosure.
  • the encoding method of FIG. 6 may be performed by the video encoding apparatus of FIG. 2. Specifically, step S610 may be performed by the inter prediction unit 180, and step S620 may be performed by the residual processing unit. Specifically, step S620 may be performed by the subtraction unit 115. Step S630 may be performed by the entropy encoding unit 190.
  • the prediction information of step S630 may be derived by the inter prediction unit 180, and the residual information of step S630 may be derived by the residual processing unit.
  • the residual information is information on the residual samples.
  • the residual information may include information on quantized transform coefficients for the residual samples.
  • the residual samples may be derived as transform coefficients through the transform unit 120 of the image encoding apparatus, and the transform coefficients may be derived as quantized transform coefficients through the quantization unit 130.
  • Information about the quantized transform coefficients may be encoded by the entropy encoding unit 190 through a residual coding procedure.
  • the image encoding apparatus may perform inter prediction on the current block (S610).
  • the image encoding apparatus may derive the inter prediction mode and motion information of the current block and generate prediction samples of the current block.
  • the procedure of determining the inter prediction mode, deriving motion information, and generating prediction samples may be performed simultaneously, or one procedure may be performed before the other procedure.
  • the inter prediction unit 180 of the image encoding apparatus may include a prediction mode determination unit 181, a motion information derivation unit 182, and a prediction sample derivation unit 183. have.
  • a prediction mode determination unit 181 determines a prediction mode for the current block
  • a motion information derivation unit 182 derives motion information of the current block
  • a prediction sample derivation unit 183 predicts the current block Samples can be derived.
  • the inter prediction unit 180 of the video encoding apparatus searches for a block similar to the current block within a predetermined area (search area) of reference pictures through motion estimation, and a difference between the current block and the current block. It is possible to derive a reference block that is less than the minimum or a certain criterion. Based on this, a reference picture index indicating a reference picture in which the reference block is located may be derived, and a motion vector may be derived based on a position difference between the reference block and the current block.
  • the image encoding apparatus may determine a mode applied to the current block from among various prediction modes.
  • the image encoding apparatus may compare rate-distortion (RD) costs for the various prediction modes and determine an optimal prediction mode for the current block.
  • RD rate-distortion
  • the method of determining the prediction mode for the current block by the image encoding apparatus is not limited to the above example, and various methods may be used.
  • the video encoding apparatus may derive merge candidates from neighboring blocks of the current block and construct a merge candidate list using the derived merge candidates.
  • the apparatus for encoding an image may derive a reference block in which a difference from a current block is a minimum or a predetermined reference or less among reference blocks indicated by merge candidates included in the merge candidate list.
  • a merge candidate associated with the derived reference block is selected, and merge index information indicating the selected merge candidate may be generated and signaled to the image decoding apparatus.
  • Motion information of the current block may be derived using motion information of the selected merge candidate.
  • the video encoding apparatus when the MVP mode is applied to the current block, the video encoding apparatus derives motion vector predictor (mvp) candidates from neighboring blocks of the current block, and constructs an mvp candidate list using the derived mvp candidates.
  • the image encoding apparatus may use a motion vector of an mvp candidate selected from among mvp candidates included in the mvp candidate list as the mvp of the current block.
  • a motion vector indicating a reference block derived by motion estimation described above may be used as a motion vector of the current block, and the difference between the motion vector of the current block among the mvp candidates is the smallest.
  • An mvp candidate having a motion vector may be the selected mvp candidate.
  • a motion vector difference (MVD) which is a difference obtained by subtracting the mvp from the motion vector of the current block may be derived.
  • index information indicating the selected mvp candidate and information about the MVD may be signaled to the video decoding apparatus.
  • the value of the reference picture index may be composed of reference picture index information and may be separately signaled to the video decoding apparatus.
  • the image encoding apparatus may derive residual samples based on the prediction samples (S620).
  • the image encoding apparatus may derive the residual samples by comparing the original samples of the current block with the prediction samples. For example, the residual sample may be derived by subtracting a corresponding prediction sample from an original sample.
  • the image encoding apparatus may encode image information including prediction information and residual information (S630).
  • the image encoding apparatus may output the encoded image information in the form of a bitstream.
  • the prediction information is information related to the prediction procedure and may include information on prediction mode information (eg, skip flag, merge flag or mode index) and motion information.
  • the skip flag is information indicating whether the skip mode is applied to the current block
  • the merge flag is information indicating whether the merge mode is applied to the current block.
  • the prediction mode information may be information indicating one of a plurality of prediction modes, such as a mode index. When the skip flag and the merge flag are each 0, it may be determined that the MVP mode is applied to the current block.
  • the information on the motion information may include candidate selection information (eg, merge index, mvp flag or mvp index) that is information for deriving a motion vector.
  • the merge index may be signaled when a merge mode is applied to the current block, and may be information for selecting one of merge candidates included in the merge candidate list.
  • the mvp flag or mvp index may be signaled when the MVP mode is applied to the current block, and may be information for selecting one of mvp candidates included in the mvp candidate list.
  • the information on the motion information may include information on the MVD and/or reference picture index information described above.
  • the information on the motion information may include information indicating whether L0 prediction, L1 prediction, or pair (Bi) prediction is applied.
  • the residual information is information on the residual samples.
  • the residual information may include information on quantized transform coefficients for the residual samples.
  • the output bitstream may be stored in a (digital) storage medium and transmitted to an image decoding device, or may be transmitted to an image decoding device through a network.
  • the image encoding apparatus may generate a reconstructed picture (a picture including reconstructed samples and a reconstructed block) based on the reference samples and the residual samples. This is because the video encoding apparatus derives the same prediction result as that performed by the video decoding apparatus, and coding efficiency can be improved through this. Accordingly, the apparatus for encoding an image may store a reconstructed picture (or reconstructed samples, and a reconstructed block) in a memory and use it as a reference picture for inter prediction. As described above, an in-loop filtering procedure or the like may be further applied to the reconstructed picture.
  • FIG. 8 is a flowchart illustrating a video/video decoding method based on inter prediction.
  • FIG. 9 is a diagram illustrating an exemplary configuration of an inter prediction unit 260 according to the present disclosure.
  • the image decoding apparatus may perform an operation corresponding to an operation performed by the image encoding apparatus.
  • the video decoding apparatus may perform prediction on the current block and derive prediction samples based on the received prediction information.
  • the decoding method of FIG. 8 may be performed by the video decoding apparatus of FIG. 3.
  • Dean systems S810 to S830 may be performed by the inter prediction unit 260, and the prediction information of step S810 and the residual information of step S840 may be obtained from the bitstream by the entropy decoding unit 210.
  • the residual processing unit of the image decoding apparatus may derive residual samples for the current block based on the residual information (S840).
  • the inverse quantization unit 220 of the residual processing unit derives transform coefficients by performing inverse quantization based on the quantized transform coefficients derived based on the residual information
  • the inverse transform unit of the residual processing unit ( 230) may derive residual samples for the current block by performing inverse transform on the transform coefficients.
  • Step S850 may be performed by the addition unit 235 or the restoration unit.
  • the image decoding apparatus may determine a prediction mode for the current block based on the received prediction information (S810).
  • the video decoding apparatus may determine which inter prediction mode is applied to the current block based on prediction mode information in the prediction information.
  • the skip mode may be applied to the current block based on the skip flag.
  • one of various inter prediction mode candidates may be selected based on the mode index.
  • the inter prediction mode candidates may include a skip mode, a merge mode and/or an MVP mode, or may include various inter prediction modes to be described later.
  • the video decoding apparatus may derive motion information of the current block based on the determined inter prediction mode (S820). For example, when a skip mode or a merge mode is applied to the current block, the video decoding apparatus may configure a merge candidate list to be described later, and select one merge candidate from among merge candidates included in the merge candidate list. The selection may be performed based on the aforementioned candidate selection information (merge index). Motion information of the current block may be derived using motion information of the selected merge candidate. For example, motion information of the selected merge candidate may be used as motion information of the current block.
  • the video decoding apparatus may configure an mvp candidate list and use a motion vector of an mvp candidate selected from among mvp candidates included in the mvp candidate list as the mvp of the current block. have.
  • the selection may be performed based on the aforementioned candidate selection information (mvp flag or mvp index).
  • the MVD of the current block may be derived based on the information on the MVD
  • a motion vector of the current block may be derived based on the mvp of the current block and the MVD.
  • a reference picture index of the current block may be derived based on the reference picture index information.
  • a picture indicated by the reference picture index in the reference picture list for the current block may be derived as a reference picture referenced for inter prediction of the current block.
  • the image decoding apparatus may generate prediction samples for the current block based on the motion information of the current block (S830).
  • the reference picture may be derived based on the reference picture index of the current block, and prediction samples of the current block may be derived using samples of a reference block indicated on the reference picture by the motion vector of the current block.
  • a prediction sample filtering procedure may be further performed on all or part of the prediction samples of the current block.
  • the inter prediction unit 260 of the image decoding apparatus may include a prediction mode determination unit 261, a motion information derivation unit 262, and a prediction sample derivation unit 263. have.
  • the inter prediction unit 260 of the video decoding apparatus determines a prediction mode for the current block based on the prediction mode information received from the prediction mode determination unit 261, and motion information received from the motion information derivation unit 262
  • the motion information (motion vector and/or reference picture index, etc.) of the current block may be derived based on the information about, and prediction samples of the current block may be derived by the prediction sample deriving unit 263.
  • the image decoding apparatus may generate residual samples for the current block based on the received residual information (S840).
  • the image decoding apparatus may generate reconstructed samples for the current block based on the prediction samples and the residual samples, and generate a reconstructed picture based on the prediction samples (S850). Thereafter, as described above, an in-loop filtering procedure or the like may be further applied to the reconstructed picture.
  • the inter prediction procedure may include determining an inter prediction mode, deriving motion information according to the determined prediction mode, and performing prediction based on the derived motion information (generating a prediction sample).
  • the inter prediction procedure may be performed in an image encoding apparatus and an image decoding apparatus.
  • inter prediction may be performed using motion information of a current block.
  • the video encoding apparatus may derive optimal motion information for the current block through a motion estimation procedure. For example, the image encoding apparatus may search for a similar reference block with high correlation using the original block in the original picture for the current block in units of fractional pixels within a predetermined search range within the reference picture, and derive motion information through this. can do.
  • the similarity of blocks can be calculated based on the sum of absolute differences (SAD) between the current block and the reference block.
  • SAD sum of absolute differences
  • motion information may be derived based on the reference block having the smallest SAD in the search area.
  • the derived motion information may be signaled to the video decoding apparatus according to various methods based on the inter prediction mode.
  • motion information of the current block is not directly transmitted, and motion information of the current block is derived using motion information of neighboring blocks. Accordingly, motion information of the current prediction block may be indicated by transmitting flag information indicating that the merge mode has been used and candidate selection information indicating which neighboring blocks are used as merge candidates (eg, merge index).
  • candidate selection information indicating which neighboring blocks are used as merge candidates (eg, merge index).
  • the current block since the current block is a unit for performing prediction, the current block is used in the same meaning as the current prediction block, and the neighboring block may be used in the same meaning as the neighboring prediction block.
  • the video encoding apparatus may search for a merge candidate block used to induce motion information of a current block. For example, up to five merge candidate blocks may be used, but the number of merge candidate blocks is not limited thereto. The maximum number of merge candidate blocks may be transmitted in a slice header or a tile group header, but is not limited thereto.
  • the image encoding apparatus may generate a merge candidate list, and among them, a merge candidate block having the smallest RD cost may be selected as a final merge candidate block.
  • the present disclosure provides various embodiments of a merge candidate block constituting the merge candidate list.
  • the merge candidate list may use, for example, five merge candidate blocks.
  • four spatial merge candidates and one temporal merge candidate can be used.
  • FIG. 10 is a diagram illustrating neighboring blocks that can be used as spatial merge candidates.
  • FIG. 11 is a diagram schematically illustrating a method of constructing a merge candidate list according to an example of the present disclosure.
  • the image encoding apparatus/image decoding apparatus may insert spatial merge candidates derived by searching for spatial neighboring blocks of the current block into the merge candidate list (S1110).
  • the spatial neighboring blocks are a block around the lower left corner of the current block (A 0 ), a neighboring block on the left (A 1 ), a block around the upper right corner (B 0 ), as shown in FIG. It may include a neighboring block B 1 and a neighboring block B 2 of the upper left corner.
  • additional neighboring blocks such as a right peripheral block, a lower peripheral block, and a right lower peripheral block may be further used as the spatial neighboring blocks.
  • the image encoding apparatus/image decoding apparatus may detect available blocks by searching for the spatial neighboring blocks based on priority, and derive motion information of the detected blocks as the spatial merge candidates. For example, the video encoding apparatus/video decoding apparatus searches the five blocks shown in FIG. 10 in the order of A 1 , B 1 , B 0 , A 0 , and B 2 and sequentially indexes the available candidates. You can build a list.
  • the image encoding apparatus/image decoding apparatus may insert a temporal merge candidate derived by searching for a temporal neighboring block of the current block into the merge candidate list (S1120).
  • the temporal neighboring block may be located on a reference picture that is a picture different from the current picture in which the current block is located.
  • the reference picture in which the temporal neighboring block is located may be referred to as a collocated picture or a col picture.
  • the temporal neighboring block may be searched in the order of a lower-right corner neighboring block and a lower-right center block of a co-located block with respect to the current block on the col picture. Meanwhile, when motion data compression is applied to reduce the memory load, specific motion information for the col picture may be stored as representative motion information for each predetermined storage unit.
  • the predetermined storage unit may be previously determined as, for example, a 16x16 sample unit or an 8x8 sample unit, or size information on the predetermined storage unit may be signaled from an image encoding apparatus to an image decoding apparatus.
  • motion information of the temporal neighboring block may be replaced with representative motion information of the predetermined storage unit in which the temporal neighboring block is located.
  • the temporal merge candidate may be derived based on motion information of a covered prediction block.
  • the coordinates of the temporally neighboring blocks (xTnb, yTnb) If la, the ((xTnb >> n) ⁇ n ) the modified position, ( Motion information of a prediction block located at yTnb>>n) ⁇ n)) may be used for the temporal merge candidate.
  • the predetermined storage unit is a 16x16 sample unit
  • the modified positions ((xTnb>>4) ⁇ 4), (yTnb The motion information of the prediction block located at >>4) ⁇ 4)) may be used for the temporal merge candidate.
  • the predetermined storage unit is an 8x8 sample unit
  • the coordinates of the temporal neighboring block are (xTnb, yTnb)
  • the modified positions ((xTnb>>3) ⁇ 3), (yTnb> Motion information of the prediction block located at >3) ⁇ 3)) may be used for the temporal merge candidate.
  • the image encoding apparatus/image decoding apparatus may check whether the number of current merge candidates is smaller than the number of maximum merge candidates (S1130).
  • the number of the maximum merge candidates may be defined in advance or may be signaled from the image encoding apparatus to the image decoding apparatus.
  • the image encoding apparatus may generate information on the number of the maximum merge candidates, encode, and transmit the information to the image decoding apparatus in the form of a bitstream.
  • a subsequent candidate addition process (S1140) may not proceed.
  • step S1130 if the number of the current merge candidates is smaller than the number of the maximum merge candidates, the video encoding apparatus/video decoding apparatus may derive an additional merge candidate according to a predetermined method and then insert it into the merge candidate list. Yes (S1140).
  • the image encoding apparatus/video decoding apparatus may terminate the construction of the merge candidate list.
  • the image encoding apparatus may select an optimal merge candidate among merge candidates constituting the merge candidate list based on RD cost, and signals candidate selection information (ex. merge index) indicating the selected merge candidate to the image decoding apparatus. can do.
  • the video decoding apparatus may select the optimal merge candidate based on the merge candidate list and the candidate selection information.
  • motion information of the selected merge candidate may be used as motion information of the current block, and prediction samples of the current block may be derived based on the motion information of the current block.
  • the image encoding apparatus may derive residual samples of the current block based on the prediction samples, and may signal residual information about the residual samples to the image decoding apparatus.
  • the image decoding apparatus may generate reconstructed samples based on the residual samples derived based on the residual information and the prediction samples, and generate a reconstructed picture based on the residual samples.
  • motion information of the current block may be derived in the same manner as previously applied to the merge mode.
  • the skip mode is applied, the residual signal for the corresponding block is omitted, and thus prediction samples can be directly used as reconstructed samples.
  • a motion vector of a reconstructed spatial neighboring block eg, a neighboring block shown in FIG. 10
  • a motion vector corresponding to a temporal neighboring block or Col block
  • a motion vector predictor (mvp) candidate list may be generated. That is, a motion vector of the reconstructed spatial neighboring block and/or a motion vector corresponding to the temporal neighboring block may be used as a motion vector predictor candidate of the current block.
  • an mvp candidate list for deriving L0 motion information and an mvp candidate list for deriving L1 motion information may be separately generated and used.
  • Prediction information (or information on prediction) for the current block is candidate selection information indicating an optimal motion vector predictor candidate selected from among motion vector predictor candidates included in the mvp candidate list (ex. MVP flag or MVP index) It may include.
  • the prediction unit may select a motion vector predictor of the current block from among the motion vector predictor candidates included in the mvp candidate list using the candidate selection information.
  • the predictor of the video encoding apparatus may obtain a motion vector difference (MVD) between the motion vector of the current block and the motion vector predictor, encode the motion vector, and output it in the form of a bitstream. That is, MVD may be obtained by subtracting the motion vector predictor from the motion vector of the current block.
  • MVD motion vector difference
  • the prediction unit of the image decoding apparatus may obtain a motion vector difference included in the prediction information, and derive the motion vector of the current block by adding the motion vector difference and the motion vector predictor.
  • the prediction unit of the video decoding apparatus may obtain or derive a reference picture index indicating a reference picture from the prediction information.
  • FIG. 12 is a diagram schematically illustrating a method of constructing a motion vector predictor candidate list according to an example of the present disclosure.
  • a spatial candidate block of the current block may be searched and an available candidate block may be inserted into the mvp candidate list (S1210). Thereafter, it is determined whether there are less than two mvp candidates included in the mvp candidate list (S1220), and if there are two, the construction of the mvp candidate list may be completed.
  • step S1220 when there are less than two available spatial candidate blocks, a temporal candidate block of the current block may be searched and an available candidate block may be inserted into the mvp candidate list (S1230).
  • the construction of the mvp candidate list may be completed by inserting a zero motion vector into the mvp candidate list (S1240).
  • a reference picture index may be explicitly signaled.
  • a reference picture index (refidxL0) for L0 prediction and a reference picture index (refidxL1) for L1 prediction may be classified and signaled.
  • refidxL0 when the MVP mode is applied and BI prediction is applied, both information on refidxL0 and information on refidxL1 may be signaled.
  • information on MVD derived from the video encoding apparatus may be signaled to the video decoding apparatus.
  • the information on the MVD may include, for example, information indicating the absolute value of the MVD and the x and y components of the sign. In this case, information indicating whether the absolute MVD value is greater than 0 and greater than 1, and the rest of the MVD may be signaled in stages. For example, information indicating whether the absolute MVD value is greater than 1 may be signaled only when a value of flag information indicating whether the absolute MVD value is greater than 0 is 1.
  • FIG. 13 is a diagram illustrating a syntax structure for transmitting MVD from an image encoding device to an image decoding device according to an example of the present disclosure.
  • abs_mvd_greater0_flag[0] indicates whether the absolute value of the x component of MVD is greater than 0
  • abs_mvd_greater0_flag[1] indicates whether the absolute value of the y component of MVD is greater than 0.
  • abs_mvd_greater1_flag[0] indicates whether the absolute value of the x component of MVD is greater than 1
  • abs_mvd_greater1_flag[1] indicates whether the absolute value of the y component of MVD is greater than 1.
  • abs_mvd_greater1_flag can be transmitted only when abs_mvd_greater0_flag is 1.
  • abs_mvd_minus2 represents a value obtained by subtracting 2 from the absolute value of MVD
  • mvd_sign_flag represents whether the sign of the MVD is positive or negative.
  • MVD[compIdx] abs_mvd_greater0_flag[compIdx] *(abs_mvd_minus2[compIdx] + 2)*(1-2 * mvd_sign_flag[compIdx])
  • MVD (MVDL0) for L0 prediction and MVD (MVDL1) for L1 prediction may be differentiated and signaled, and the information on MVD may include information on MVDL0 and/or information on MVDL1.
  • the MVP mode is applied to the current block and BI prediction is applied, both the information on the MVDL0 and the information on the MVDL1 may be signaled.
  • the IBC prediction may be performed by a prediction unit of an image encoding apparatus/image decoding apparatus.
  • the IBC prediction can be simply called IBC.
  • the IBC may be used for content image/movie coding such as games, such as, for example, screen content coding (SCC).
  • SCC screen content coding
  • the IBC basically performs prediction in the current picture, but may be performed similarly to inter prediction in that it derives a reference block in the current picture. That is, the IBC may use at least one of the inter prediction techniques described in this disclosure. For example, in IBC, at least one of the aforementioned methods of deriving motion information (motion vector) may be used. At least one of the inter prediction techniques may be partially modified and used in consideration of the IBC prediction.
  • the IBC may refer to the current picture, and thus may be referred to as CPR (current picture referencing).
  • the video encoding apparatus may derive an optimal block vector (or motion vector) for a current block (ex. CU) by performing block matching (BM).
  • the derived block vector (or motion vector) may be signaled to an image decoding apparatus through a bitstream using a method similar to signaling of motion information (motion vector) in the above-described inter prediction.
  • the video decoding apparatus may derive a reference block for the current block in the current picture through the signaled block vector (motion vector), and through this, a prediction signal (predicted block or prediction samples) for the current block.
  • the block vector (or motion vector) may represent a displacement from a current block to a reference block located in an already reconstructed area in the current picture.
  • the block vector (or motion vector) may be called a displacement vector.
  • the motion vector may correspond to the block vector or the displacement vector.
  • the motion vector of the current block may include a motion vector for a luma component (a luma motion vector) or a motion vector for a chroma component (a chroma motion vector).
  • the luma motion vector for the IBC coded CU may be in integer sample units (ie, integer precision).
  • the chroma motion vector can also be clipped in units of integer samples.
  • the IBC may use at least one of inter prediction techniques, and for example, the luma motion vector may be encoded/decoded using the merge mode or the MVP mode described above.
  • the merge candidate list for the luma IBC block may be configured similarly to the merge candidate list in the inter mode described with reference to FIG. 11.
  • a temporal neighboring block may not be used as a merge candidate.
  • the mvp candidate list for the luma IBC block may be configured similarly to the mvp candidate list in the inter mode described with reference to FIG. 12. However, in the case of a luma IBC block, a temporal candidate block may not be used as an mvp candidate.
  • the IBC derives a reference block from an already reconstructed area in the current picture.
  • a predefined area among the reconstructed areas in the current picture may be referenced.
  • the predefined area may include a current CTU including a current block.
  • An image encoding apparatus performing IBC may search for the predefined area to determine a reference block having the smallest RD cost, and derive a motion vector (block vector) based on the positions of the reference block and the current block.
  • IBC performance information Whether to apply IBC to the current block may be signaled as IBC performance information at the CU level.
  • Information on a signaling method (IBC MVP mode or IBC skip/merge mode) of the motion vector of the current block may be signaled.
  • the IBC performance information may be used to determine the prediction mode of the current block. Accordingly, the IBC performance information may be included in the information on the prediction mode of the current block.
  • a merge candidate index may be signaled and used to indicate a block vector to be used for prediction of a current luma block among block vectors included in the merge candidate list.
  • the merge candidate list may include neighboring blocks encoded with IBC.
  • the merge candidate list may include a spatial merge candidate and may be configured not to include a temporal merge candidate.
  • the merge candidate list may additionally include a history-based motion vector predictor (HMVP) candidate and/or a pairwise candidate.
  • HMVP history-based motion vector predictor
  • the block vector difference value may be encoded in the same manner as the motion vector difference value of the aforementioned inter mode.
  • the block vector prediction method may construct and use an mvp candidate list including two candidates as predictors, similar to the MVP mode of the inter mode.
  • One of the two candidates may be derived from a left neighboring block, and the other one may be derived from an upper neighboring block.
  • a candidate can be derived from the neighboring block only when the left or upper neighboring block is encoded by IBC. If the left or upper neighboring block is not available, for example, if it is not encoded by IBC, a default block vector may be included in the mvp candidate list as a predictor.
  • the mvp candidate list may include an HMVP candidate and/or a zero motion vector as a default block vector.
  • the HMVP candidate may be referred to as a history-based MVP candidate, and the MVP candidate, merge candidate, or block vector candidate used before encoding/decoding of the current block may be stored in the HMVP list as the HMVP candidate. Thereafter, when the merge candidate list or mvp candidate list of the current block does not include the maximum number of candidates, the candidates stored in the HMVP list may be added to the merge candidate list or mvp candidate list of the current block as HMVP candidates.
  • the pairwise candidate refers to a candidate derived by selecting two candidates according to a predetermined order among candidates already included in the merge candidate list of the current block and averaging the selected two candidates.
  • FIG. 14 is a flowchart illustrating an IBC-based video/video encoding method.
  • 15 is a diagram illustrating a configuration of a prediction unit that performs an IBC-based video/video encoding method according to the present disclosure.
  • the encoding method of FIG. 14 may be performed by the video encoding apparatus of FIG. 2. Specifically, step S1410 may be performed by the prediction unit, and step S1420 may be performed by the residual processing unit. Specifically, step S1420 may be performed by the subtraction unit 115. Step S1430 may be performed by the entropy encoding unit 190.
  • the prediction information of step S1430 may be derived by the prediction unit, and the residual information of step S1430 may be derived by the residual processing unit.
  • the residual information is information on the residual samples.
  • the residual information may include information on quantized transform coefficients for the residual samples.
  • the residual samples may be derived as transform coefficients through the transform unit 120 of the image encoding apparatus, and the transform coefficients may be derived as quantized transform coefficients through the quantization unit 130.
  • Information about the quantized transform coefficients may be encoded by the entropy encoding unit 190 through a residual coding procedure.
  • the image encoding apparatus may perform IBC prediction (IBC-based prediction) on the current block (S1410).
  • the image encoding apparatus may derive a prediction mode and a motion vector (block vector) of the current block, and generate prediction samples of the current block.
  • the prediction mode may include at least one of the aforementioned inter prediction modes.
  • a procedure for determining a prediction mode, deriving a motion vector, and generating prediction samples may be performed simultaneously, or one procedure may be performed prior to another procedure.
  • a prediction unit of an image encoding apparatus that performs an IBC-based video/image encoding method may include a prediction mode determination unit, a motion vector derivation unit, and a prediction sample derivation unit.
  • a prediction mode determination unit may determine a prediction mode for the current block, a motion vector derivation unit may derive a motion vector of the current block, and a prediction sample derivation unit may derive prediction samples of the current block.
  • the prediction unit of the video encoding apparatus searches for a block similar to the current block within the reconstructed area (or a certain area (search area) of the reconstructed area) of the current picture, and the difference from the current block is minimal or Reference blocks below a certain standard can be derived.
  • the image encoding apparatus may derive a motion vector based on a difference in displacement between the reference block and the current block.
  • the image encoding apparatus may determine a mode applied to the current block from among various prediction modes.
  • the video encoding apparatus may compare rate-distortion costs for the various prediction modes and determine an optimal prediction mode for the current block.
  • the method of determining the prediction mode for the current block by the image encoding apparatus is not limited to the above example, and various methods may be used.
  • the video encoding apparatus may derive merge candidates from neighboring blocks of the current block and construct a merge candidate list using the derived merge candidates.
  • the image encoding apparatus may derive a reference block in which a difference between the current block and the current block among reference blocks indicated by merge candidates included in the merge candidate list is a minimum or less than a predetermined reference.
  • a merge candidate associated with the derived reference block is selected, and merge index information indicating the selected merge candidate may be generated and signaled to the image decoding apparatus.
  • the motion vector of the current block may be derived by using the motion vector of the selected merge candidate.
  • the video encoding apparatus when the MVP mode is applied to the current block, the video encoding apparatus derives motion vector predictor (mvp) candidates from neighboring blocks of the current block, and constructs an mvp candidate list using the derived mvp candidates.
  • the image encoding apparatus may use a motion vector of an mvp candidate selected from among mvp candidates included in the mvp candidate list as the mvp of the current block.
  • a motion vector indicating a reference block derived by motion estimation described above may be used as a motion vector of the current block, and the difference between the motion vector of the current block among the mvp candidates is the smallest.
  • An mvp candidate having a motion vector may be the selected mvp candidate.
  • a motion vector difference (MVD) which is a difference obtained by subtracting the mvp from the motion vector of the current block may be derived.
  • index information indicating the selected mvp candidate and information about the MVD may be signaled to the video decoding apparatus.
  • the image encoding apparatus may derive residual samples based on the prediction samples (S1420).
  • the image encoding apparatus may derive the residual samples by comparing the original samples of the current block with the prediction samples. For example, the residual sample may be derived by subtracting a corresponding prediction sample from an original sample.
  • the image encoding apparatus may encode image information including prediction information and residual information (S1430).
  • the image encoding apparatus may output the encoded image information in the form of a bitstream.
  • the prediction information is information related to the prediction procedure and may include prediction mode information (eg, skip flag, merge flag or mode index, etc.) and information on a motion vector.
  • the prediction mode information e.g, skip flag, merge flag or mode index, etc.
  • the skip flag is information indicating whether the skip mode is applied to the current block
  • the merge flag is information indicating whether the merge mode is applied to the current block.
  • the prediction mode information may be information indicating one of a plurality of prediction modes, such as a mode index. When the skip flag and the merge flag are each 0, it may be determined that the MVP mode is applied to the current block.
  • the information on the motion vector may include candidate selection information (eg, merge index, mvp flag or mvp index) that is information for deriving a motion vector.
  • candidate selection information eg, merge index, mvp flag or mvp index
  • the merge index may be signaled when a merge mode is applied to the current block, and may be information for selecting one of merge candidates included in the merge candidate list.
  • the mvp flag or mvp index may be signaled when the MVP mode is applied to the current block, and may be information for selecting one of mvp candidates included in the mvp candidate list.
  • the information on the motion vector may include information on the above-described MVD.
  • the information on the motion vector may include information indicating whether L0 prediction, L1 prediction, or bi prediction is applied.
  • the residual information is information on the residual samples.
  • the residual information may include information on quantized transform coefficients for the residual samples.
  • the output bitstream may be stored in a (digital) storage medium and transmitted to an image decoding device, or may be transmitted to an image decoding device through a network.
  • the image encoding apparatus may generate a reconstructed picture (a picture including reconstructed samples and a reconstructed block) based on the reference samples and the residual samples. This is because the video encoding apparatus derives the same prediction result as that performed by the video decoding apparatus, and coding efficiency can be improved through this. Accordingly, the apparatus for encoding an image may store a reconstructed picture (or reconstructed samples, and a reconstructed block) in a memory and use it as a reference picture for inter prediction. As described above, an in-loop filtering procedure or the like may be further applied to the reconstructed picture.
  • 16 is a flowchart illustrating an IBC-based video/video decoding method.
  • 17 is a diagram illustrating a configuration of a prediction unit that performs an IBC-based video/video decoding method according to the present disclosure.
  • the image decoding apparatus may perform an operation corresponding to an operation performed by the image encoding apparatus.
  • the image decoding apparatus may perform IBC prediction on the current block and derive prediction samples based on the received prediction information.
  • the decoding method of FIG. 16 may be performed by the video decoding apparatus of FIG. 3.
  • Dean systems S1610 to S1630 may be performed by the prediction unit, and the prediction information of step S1610 and the residual information of step S1640 may be obtained from the bitstream by the entropy decoding unit 210.
  • the residual processing unit of the image decoding apparatus may derive residual samples for the current block based on the residual information (S1640).
  • the inverse quantization unit 220 of the residual processing unit derives transform coefficients by performing inverse quantization based on the quantized transform coefficients derived based on the residual information
  • the inverse transform unit of the residual processing unit ( 230) may derive residual samples for the current block by performing inverse transform on the transform coefficients.
  • Step S1650 may be performed by the addition unit 235 or the restoration unit.
  • the image decoding apparatus may determine a prediction mode for the current block based on the received prediction information (S1610).
  • the video decoding apparatus may determine which prediction mode is applied to the current block based on prediction mode information in the prediction information.
  • the prediction mode candidates may include a skip mode, a merge mode and/or an MVP mode, or may include the aforementioned various inter prediction modes.
  • the image decoding apparatus may derive a motion vector of the current block based on the determined prediction mode (S1620). For example, when a skip mode or a merge mode is applied to the current block, the video decoding apparatus may configure the above-described merge candidate list and select one merge candidate from among merge candidates included in the merge candidate list. The selection may be performed based on the aforementioned candidate selection information (merge index).
  • the motion vector of the current block may be derived by using the motion vector of the selected merge candidate. For example, the motion vector of the selected merge candidate may be used as the motion vector of the current block.
  • the video decoding apparatus may configure an mvp candidate list and use a motion vector of an mvp candidate selected from among mvp candidates included in the mvp candidate list as the mvp of the current block. have.
  • the selection may be performed based on the aforementioned candidate selection information (mvp flag or mvp index).
  • the MVD of the current block may be derived based on the information on the MVD, and a motion vector of the current block may be derived based on the mvp of the current block and the MVD.
  • the image decoding apparatus may generate prediction samples for the current block based on the motion vector of the current block (S1630). Predictive samples of the current block may be derived using samples of a reference block indicated by the motion vector of the current block on the current picture. In some cases, a prediction sample filtering procedure may be further performed on all or part of the prediction samples of the current block.
  • a prediction unit of an image decoding apparatus may include a prediction mode determination unit, a motion vector derivation unit, and a prediction sample derivation unit.
  • the prediction unit of the video decoding apparatus determines a prediction mode for the current block based on the prediction mode information received from the prediction mode determination unit, and moves the current block based on the information on the motion vector received from the motion vector derivation unit.
  • a vector may be derived, and a prediction sample deriving unit may derive prediction samples of the current block.
  • the image decoding apparatus may generate residual samples for the current block based on the received residual information (S1640).
  • the image decoding apparatus may generate reconstructed samples for the current block based on the prediction samples and the residual samples, and generate a reconstructed picture based on the prediction samples. (S1650). Thereafter, as described above, an in-loop filtering procedure or the like may be further applied to the reconstructed picture.
  • one unit may include a luma block (a luma coding block (CB)) and a chroma block (chroma CB).
  • the luma block and the corresponding chroma block may have the same motion information (eg, a motion vector) or different motion information.
  • the motion information of the chroma block is derived based on the motion information of the luma block, so that the luma block and the corresponding chroma block may have the same motion information.
  • the encoding apparatus can encode a motion vector for a prediction block similarly to the operation of the decoding apparatus described later, the following decoding apparatus will be mainly described, and then the description of the encoding apparatus will be described later.
  • the candidate reference block 1820 is a diagram illustrating a current block 1810 and a candidate reference block 1820 which are decoding target blocks.
  • the candidate reference block 1820 may be indicated by a motion vector candidate 1811 derived from a neighboring block of the current block 1810.
  • the candidate reference block 1820 is located in the same picture as the current block 1810.
  • an overlapping region 1822 in which a portion of the candidate reference block 1820 overlaps the current block 1810 may exist.
  • the overlapping area is shown by hatching in FIG. 18.
  • the sample values of the candidate reference block 1820 may not be reconstructed with respect to the overlapping area 1822. Accordingly, there occurs a problem that the current block 1810 cannot be reconstructed using the candidate reference block 1820.
  • the motion vector candidate 1911 of the current block may be modified.
  • 19 is a diagram illustrating an embodiment in which a motion vector candidate 1911 of a current block is modified.
  • the motion vector candidate 1911 may be modified to refer to the candidate reference block 1910 located in the designated area.
  • the decoding apparatus may update the candidate reference block 1910 as follows. This will be described with reference to FIG. 20.
  • the decoding apparatus may determine the availability of a candidate reference block indicated by the motion vector candidate of the current block (S2010).
  • the decoding apparatus may determine the availability of the candidate reference block according to whether all samples of the candidate reference block have already been reconstructed.
  • the decoding apparatus may determine the candidate reference block as a block usable for prediction and determine that it is available. have. If at least one sample value of the candidate reference blocks has not been restored or is not stored in the memory, the decoding apparatus may determine that the candidate reference block is a block that cannot be used for prediction and determines that the candidate reference block is not available.
  • the decoding apparatus may determine that the candidate reference block can be used for prediction. For example, the decoding apparatus may determine the availability of a corresponding candidate reference block based on a lower right position of the candidate reference block and an upper left position of the current block. Alternatively, the decoding apparatus may determine the availability of the corresponding candidate reference block based on the motion vector candidate and the size of the current block.
  • the decoding apparatus may update the candidate reference block (S2020).
  • the decoding apparatus may update the candidate reference block with the selected block 1910 from among the reconstructed regions in the current picture.
  • the decoding apparatus may update the candidate reference block 1910 by modifying the motion vector candidate 1911.
  • the decoding apparatus may perform prediction of the current block by using the updated candidate reference block (S2030).
  • the decoding apparatus may reconstruct the current block by using the prediction block generated as a result of prediction of the current block and the residual block obtained from the bitstream.
  • the example of the current block 1810 and the candidate reference block 1820 shown in FIG. 18 is an example of a condition in which the candidate reference block is not available, and the current block 1810 and the candidate reference block 1910 shown in FIG.
  • a method for determining availability of a candidate reference block will be described below by taking an example as an example of a condition in which the candidate reference block is available.
  • the corresponding candidate reference block 1820 when the lower right position of the candidate reference block 1820 is located lower right than the upper left position of the current block 1810, the corresponding candidate reference block 1820 is not available. It can be decided not. Meanwhile, as shown in FIG. 19, when the lower right position of the candidate reference block 1910 is positioned above the upper left position of the current block 1810 or positioned to the left of the upper left position, the corresponding candidate reference block ( 1910) can be judged as available.
  • 21 is a flowchart illustrating a method of determining availability of a candidate reference block by comparing a lower right position of a candidate reference block and an upper left position of a current block, by a decoding apparatus according to an embodiment.
  • the decoding apparatus may determine whether the x-coordinate value of the lower-right sample of the candidate reference block is smaller than the x-coordinate value of the upper-left sample of the current block (S2110). In such a case, the decoding apparatus may determine that the candidate reference block is available (S2120).
  • the decoding apparatus may determine whether the y-coordinate value of the lower-right sample of the candidate reference block is smaller than the y-coordinate value of the upper-left sample of the current block (S2130). In such a case, the decoding apparatus may determine that the candidate reference block is available (S2120). Meanwhile, if not, the decoding apparatus may determine that the corresponding candidate reference block is not available (S2140). In this embodiment, the decoding apparatus may perform the steps S2110 and S2130 by changing the order.
  • the decoding apparatus may determine the availability of the candidate reference block based on the motion vector candidate of the current block and the size of the current block.
  • the absolute value of the x component of the motion vector candidate 1811 is smaller than the width of the current block 1810, and the absolute value of the y component of the motion vector candidate 1811 is the current block. If it is smaller than the height of (1810), it may be determined that the candidate reference block 1820 indicated by the motion vector candidate 1811 is not available. Meanwhile, as illustrated in FIG.
  • the absolute value of the x component of the motion vector candidate 1911 is equal to or greater than the width of the current block 1810, or the absolute value of the y component of the motion vector candidate 1911 is the current block 1810. If it is equal to or greater than the height of, the candidate reference block 1910 indicated by the corresponding motion vector candidate 1911 may be determined to be available.
  • the decoding apparatus may determine whether the absolute value of the x component of the motion vector candidate is greater than or equal to the width of the current block (S2210). In such a case, the decoding apparatus may determine that the candidate reference block is available (S2220). Meanwhile, if not, the decoding apparatus may determine whether the absolute value of the y component of the motion vector candidate is equal to or greater than the height of the current block (S2230). In such a case, the decoding apparatus may determine that the candidate reference block is available (S2220). Meanwhile, if not, the decoding apparatus may determine that the corresponding candidate reference block is not available (S2240). Even in this embodiment, the decoding apparatus may perform the steps S2210 and S2230 by changing the order.
  • 23 is a diagram for describing a method of updating a candidate reference block in a horizontal direction.
  • the current candidate reference block 1820 as shown in FIG. 23 A candidate reference block of the current block 1810 may be updated with a candidate reference block 2310 located in the horizontal direction of and not overlapping with the current block 1810.
  • the decoding apparatus sets the x-coordinate of an upper-left sample used when specifying a candidate reference block to a value obtained by subtracting the width of the current block from the x-coordinate of the upper-left sample of the current block, as shown in FIG.
  • the reference block 2310 may be updated.
  • the decoding apparatus may update the candidate reference block to a block further spaced apart from the current block by increasing a value subtracted from the x-coordinate of the upper left sample of the current block. In this case, the subtracted value may be limited so that one area of the candidate reference block does not deviate from the current picture.
  • the decoding apparatus sets the x component of the motion vector candidate of the current block as a value of the width of the current block, and maintains the sign of the x component as it is, thereby indicating the updated candidate reference block.
  • the decoding apparatus may update the candidate reference block to a block further spaced apart from the current block by setting the x component of the motion vector candidate to a value larger than the width of the current block. In this case, the subtracted value may be limited so that one area of the candidate reference block does not deviate from the current picture.
  • 24 is a diagram illustrating a method of updating a candidate reference block in a vertical direction.
  • the decoding apparatus when a region of the current candidate reference block 1820 overlaps with a region of the current block 1810 as shown in FIG. 18, the vertical direction of the current candidate reference block 1820 as shown in FIG.
  • the candidate reference block may be updated with the candidate reference block 2410 located at and not overlapping with the current block.
  • the decoding apparatus sets the y-coordinate of the upper-left sample used when specifying the candidate reference block to a value obtained by subtracting the height of the current block 1810 from the y-coordinate of the upper-left sample of the current block 1810. , As shown in FIG. 24, the candidate reference block 2410 may be updated. Also, the decoding apparatus according to an embodiment may update a candidate reference block to a block further spaced apart from the current block by increasing a value subtracted from the y-coordinate of the upper left sample of the current block. In this case, the subtracted value may be limited so that one area of the candidate reference block does not deviate from the current picture.
  • the decoding apparatus sets the y component of the motion vector candidate as a value of the height of the current block 1810 and maintains the sign of the y component to indicate the updated candidate reference block 2410. It is also possible to update the motion vector candidate. Also, the decoding apparatus according to an embodiment may update the candidate reference block to a block further separated from the current block by setting the y component of the motion vector candidate of the current block to a value greater than the height of the current block. In this case, the subtracted value may be limited so that one area of the candidate reference block does not deviate from the current picture.
  • 25 is a diagram illustrating a method of updating a candidate reference block in a diagonal direction.
  • the decoding apparatus when an area of the candidate reference block 1820 overlaps with an area of the current block 1810 as shown in FIG. 18, the decoding apparatus is located in a diagonal direction of the current block 1810, as shown in FIG. , The candidate reference block may be updated with a candidate reference block 2510 that does not overlap with the current block 1810.
  • the decoding apparatus sets the x-coordinate of the upper-left sample used when specifying the candidate reference block as a value obtained by subtracting the width of the current block from the x-coordinate of the upper-left sample of the current block 1810, and refers to the candidate.
  • the candidate reference block 2510 is updated as shown in FIG. 25 by setting the y-coordinate of the upper-left sample used when specifying the block to a value obtained by subtracting the height of the current block from the y-coordinate of the upper-left sample of the current block 1810. can do.
  • the decoding apparatus may update the candidate reference block to a block further spaced apart from the current block by increasing values subtracted from the x-coordinate and y-coordinate of the upper left sample of the current block.
  • the subtracted value may be limited so that one area of the candidate reference block does not deviate from the current picture.
  • the decoding apparatus sets the x component of the motion vector candidate as a value of the width of the current block 1810, maintains the sign of the x component, and sets the y component of the motion vector candidate to the current block 1810. ), and by maintaining the sign of the y component as it is, the motion vector candidate may be updated to indicate the updated candidate reference block 2510.
  • the decoding apparatus sets the x and y components of the motion vector candidate of the current block 1810 to a value larger than the width and height of the current block 1810 to refer to the candidate as a block further spaced apart from the current block. Blocks can also be updated. In this case, the set value may be limited so that a region of the candidate reference block does not deviate from the current picture.
  • 26 is a diagram for describing a method of updating a candidate reference block in a direction indicated by a motion vector candidate.
  • the decoding apparatus according to an embodiment is positioned in the direction indicated by the motion vector candidate 2611 as shown in FIG. 26 when a region of the candidate reference block 1820 overlaps the region of the current block 1810 as shown in FIG.
  • the candidate reference block may be updated with the candidate reference block 2610 that does not overlap the current block 1810.
  • the decoding apparatus may update the candidate reference block 2610 as shown in FIG. 26 by scaling the x and y components of the motion vector candidate 2611.
  • the decoding apparatus may update the candidate reference block 2610 by multiplying the x component and the y component by the same scaling factor.
  • the absolute value of the x component of the scaled motion vector candidate 2611 is greater than or equal to the width of the current block, or the absolute value of the y component of the scaled motion vector candidate is greater than the height of the current block.
  • the decoding apparatus may update the candidate reference block to a block adjacent to the current block 1810 and one side of the upper or left side. 26 shows a candidate reference block 2610 in contact with the left side of the current block 1810.
  • the decoding apparatus may update the candidate reference block with a block further separated from the current block by selecting a scaling factor having a larger value. In this case, the value of the scaling factor may be limited so that a region of the candidate reference block does not deviate from the current picture.
  • a scale factor is added to the values of the x and y components of the motion vector candidate of the current block or the x and y coordinates of the upper left sample of the candidate reference block.
  • the candidate reference block 2710 may be updated.
  • the decoding apparatus may update a motion vector candidate or a candidate reference block by adding a scale motion vector 2711 composed of a scale coefficient to the motion vector candidate 2611 as shown in FIG. 27.
  • the horizontal scale coefficient added to the x component (x coordinate) and the vertical scale coefficient added to the y component (y coordinate) may be set to the same value as shown in FIG. 27 or different values.
  • the ratio between the horizontal scale factor and the vertical scale factor may follow the ratio of the width and height of the current block.
  • the decoding apparatus may update the candidate reference block to a block further spaced apart from the current block by selecting a value of the scaling factor having a larger value.
  • the value of the scaling factor may be limited so that a region of the candidate reference block does not deviate from the current picture.
  • the above-described update of the candidate reference block or the motion vector candidate may be applied to the merge mode for the IBC mode and the AMVP mode.
  • the decoding apparatus may perform the above-described motion vector candidate update to construct a merge candidate list for an IBC mode or an MVP candidate list for an AMVP mode.
  • the motion vector candidate list may include a merge candidate list and/or an MVP candidate list. Both the merge candidate list and the MVP candidate list are in the form of a list, and may include a motion vector of a block adjacent to the current block as a motion vector candidate for determining a motion vector of the current block.
  • a method of performing decoding by applying the above-described motion vector candidate update to the merge candidate and the MVP candidate will be described.
  • the decoding apparatus may determine a prediction mode of the current block based on prediction mode information of the current block obtained from a bitstream (S2810).
  • the prediction mode of the current block is the Intra Block Copy (IBC) mode
  • the decoding apparatus may determine a motion vector of the current block based on a motion vector candidate derived from a neighboring block of the current block (S2820).
  • the decoding apparatus may generate a motion vector candidate list based on whether a block indicated by a motion vector candidate overlaps a current block.
  • the decoding apparatus may determine a motion vector of the current block based on the motion vector candidate selected from the motion vector candidate list. Next, the decoding apparatus may determine a prediction block of the current block based on the determined motion vector (S2830). Next, the decoding apparatus may generate a reconstructed block of the current block by using the prediction block (S2840).
  • the decoding apparatus may construct a motion vector candidate list by applying the above-described motion vector candidate update.
  • 29 is a flowchart illustrating a method of constructing a motion vector candidate list by determining availability of a motion vector candidate by a decoding apparatus according to an embodiment.
  • the decoding apparatus may determine whether a current motion vector candidate is available (S2910). As described above with reference to FIGS. 18 to 22, the decoding apparatus may determine whether a current motion vector candidate is available. If the current motion vector candidate is available, the decoding apparatus may add it to the motion vector candidate list (S2920).
  • the decoding apparatus may determine the corrected motion vector candidate as described above with reference to FIGS. 23 to 27. Next, the decoding apparatus may determine whether the modified motion vector candidate exists in the motion vector candidate list (S2930). If the modified motion vector candidate exists in the list, the decoding apparatus may discard the current motion vector candidate without adding it to the list (S2940). Meanwhile, when the modified motion vector candidate does not exist in the list, the decoding apparatus may add the modified motion vector candidate to the list.
  • the decoding apparatus may update a motion vector candidate included in a previously constructed motion vector candidate list based on whether or not they overlap with a current block.
  • the decoding apparatus may generate a motion vector candidate list by using a motion vector of a block adjacent to the current block (S3010).
  • the decoding apparatus may determine whether there is a motion vector candidate that is not available in the motion vector candidate list (S3020). As described above with reference to FIGS. 18 to 22, the decoding apparatus may determine whether there is a motion vector candidate that is not available in the motion vector candidate list. If there is no motion vector candidate that is not available, the decoding apparatus may maintain the current list without modification (S3030).
  • the decoding apparatus may determine the corrected motion vector candidate as described above with reference to FIGS. 23 to 27. In addition, the decoding apparatus may determine whether the modified motion vector candidate exists in the motion vector candidate list (S3040). When the modified motion vector candidate exists in the motion vector candidate list, the decoding apparatus may remove an unavailable motion vector candidate from the motion vector candidate list (S3050). For example, the decoding apparatus may update an unavailable motion vector candidate with a preset additional motion vector candidate such as a zero vector as described above. Meanwhile, when the modified motion vector candidate does not exist in the motion vector candidate list, the decoding apparatus may update a motion vector candidate that is not available in the motion vector candidate list to the modified motion vector candidate (S3060). For example, the decoding apparatus may update a value of a motion vector candidate that is not available in the list to a value of the modified motion vector candidate.
  • FIG. 31 is a diagram illustrating a method of encoding an image using updating of a candidate reference block or a motion vector candidate by an encoding apparatus according to an embodiment.
  • the encoding apparatus according to an embodiment may predict a current block in a plurality of prediction modes and perform encoding to find an optimal encoding method for the current block.
  • the encoding apparatus may select an IBC mode as a prediction mode of the current block (S3110).
  • the encoding apparatus may generate a prediction block of the current block in the current picture and generate a motion vector indicating this (S3120). Further, the encoding apparatus may encode the current block based on the prediction block, and may encode the motion vector of the current block based on a motion vector candidate derived from a neighboring block of the current block (S3130).
  • the encoding apparatus may use a merge mode or an AMVP mode to encode a motion vector of a current block.
  • the encoding apparatus may determine whether the merge candidate or the candidate reference block indicated by the MVP candidate is available by using the above-described motion vector candidate availability determination method.
  • the encoding apparatus may update the merge candidate or the MVP candidate based on the availability determination result, and may generate a merge candidate list or an MVP candidate list based on this, or update a previously generated list. Accordingly, the encoding apparatus may encode the motion vector of the current block based on the merge candidate list or the MVP candidate list to which the above-described motion vector update method is applied.
  • Exemplary methods of the present disclosure are expressed as a series of operations for clarity of explanation, but this is not intended to limit the order in which steps are performed, and each step may be performed simultaneously or in a different order if necessary.
  • the illustrative steps may include additional steps, other steps may be included excluding some steps, or may include additional other steps excluding some steps.
  • an image encoding apparatus or an image decoding apparatus performing a predetermined operation may perform an operation (step) of confirming an execution condition or situation of the operation (step). For example, when it is described that a predetermined operation is performed when a predetermined condition is satisfied, the video encoding apparatus or the video decoding apparatus performs an operation to check whether the predetermined condition is satisfied, and then performs the predetermined operation. I can.
  • various embodiments of the present disclosure may be implemented by hardware, firmware, software, or a combination thereof.
  • one or more ASICs Application Specific Integrated Circuits
  • DSPs Digital Signal Processors
  • DSPDs Digital Signal Processing Devices
  • PLDs Programmable Logic Devices
  • FPGAs Field Programmable Gate Arrays
  • general purpose It may be implemented by a processor (general processor), a controller, a microcontroller, a microprocessor, or the like.
  • the image decoding device and the image encoding device to which the embodiment of the present disclosure is applied include a multimedia broadcasting transmission/reception device, a mobile communication terminal, a home cinema video device, a digital cinema video device, a surveillance camera, a video chat device, and a real-time communication device such as video communication.
  • Mobile streaming devices storage media, camcorders, video-on-demand (VoD) service providers, OTT video (Over the top video) devices, Internet streaming service providers, three-dimensional (3D) video devices, video telephony video devices, and medical use. It may be included in a video device or the like, and may be used to process a video signal or a data signal.
  • an OTT video (Over the top video) device may include a game console, a Blu-ray player, an Internet-connected TV, a home theater system, a smartphone, a tablet PC, and a digital video recorder (DVR).
  • DVR digital video recorder
  • FIG. 32 is a diagram illustrating a content streaming system to which an embodiment of the present disclosure can be applied.
  • the content streaming system to which the embodiment of the present disclosure is applied may largely include an encoding server, a streaming server, a web server, a media storage device, a user device, and a multimedia input device.
  • the encoding server serves to generate a bitstream by compressing content input from multimedia input devices such as smartphones, cameras, camcorders, etc. into digital data, and transmits it to the streaming server.
  • multimedia input devices such as smartphones, cameras, camcorders, etc. directly generate bitstreams
  • the encoding server may be omitted.
  • the bitstream may be generated by an image encoding method and/or an image encoding apparatus to which an embodiment of the present disclosure is applied, and the streaming server may temporarily store the bitstream in a process of transmitting or receiving the bitstream.
  • the streaming server may transmit multimedia data to a user device based on a user request through a web server, and the web server may serve as an intermediary for notifying the user of a service.
  • the web server transmits the request to the streaming server, and the streaming server may transmit multimedia data to the user.
  • the content streaming system may include a separate control server, and in this case, the control server may play a role of controlling a command/response between devices in the content streaming system.
  • the streaming server may receive content from a media storage and/or encoding server. For example, when content is received from the encoding server, the content may be received in real time. In this case, in order to provide a smooth streaming service, the streaming server may store the bitstream for a predetermined time.
  • Examples of the user device include a mobile phone, a smart phone, a laptop computer, a digital broadcasting terminal, a personal digital assistant (PDA), a portable multimedia player (PMP), a navigation system, a slate PC, and Tablet PC, ultrabook, wearable device, for example, smartwatch, smart glass, head mounted display (HMD)), digital TV, desktop There may be computers, digital signage, etc.
  • PDA personal digital assistant
  • PMP portable multimedia player
  • HMD head mounted display
  • TV desktop
  • desktop There may be computers, digital signage, etc.
  • Each server in the content streaming system may be operated as a distributed server, and in this case, data received from each server may be distributedly processed.
  • the scope of the present disclosure is software or machine-executable instructions (e.g., operating systems, applications, firmware, programs, etc.) that cause an operation according to the method of various embodiments to be executed on a device or computer, and such software or It includes a non-transitory computer-readable medium (non-transitory computer-readable medium) which stores instructions and the like and is executable on a device or a computer.
  • a non-transitory computer-readable medium non-transitory computer-readable medium
  • An embodiment according to the present disclosure may be used to encode/decode an image.

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Abstract

L'invention concerne un procédé et un appareil de codage/décodage d'images. Un procédé de décodage d'image selon l'invention comprend les étapes consistant à : déterminer un mode de prédiction d'un bloc actuel sur la base d'informations de mode de prédiction concernant le bloc actuel acquises à partir d'un flux binaire ; déterminer un vecteur de mouvement du bloc actuel sur la base d'un candidat de vecteur de mouvement dérivé d'un bloc périphérique du bloc actuel lorsque le mode de prédiction du bloc actuel est un mode de copie intra-bloc (IBC) ; déterminer un bloc de prédiction du bloc actuel sur la base du vecteur de mouvement ; et générer un bloc de restauration du bloc actuel en utilisant le bloc de prédiction. Le vecteur de mouvement du bloc actuel peut être déterminé sur la base des informations concernant le candidat de vecteur de mouvement et la taille du bloc actuel.
PCT/KR2020/003409 2019-03-11 2020-03-11 Procédé et appareil de codage/décodage d'images utilisant la prédiction ibc, et procédé de transmission d'un flux binaire Ceased WO2020184990A1 (fr)

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