WO2020130705A1 - Procédé et appareil pour coder des niveaux de coefficients de transformée de coefficients de transformée - Google Patents

Procédé et appareil pour coder des niveaux de coefficients de transformée de coefficients de transformée Download PDF

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WO2020130705A1
WO2020130705A1 PCT/KR2019/018177 KR2019018177W WO2020130705A1 WO 2020130705 A1 WO2020130705 A1 WO 2020130705A1 KR 2019018177 W KR2019018177 W KR 2019018177W WO 2020130705 A1 WO2020130705 A1 WO 2020130705A1
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Prior art keywords
transform coefficient
transform
flag
level
level flag
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PCT/KR2019/018177
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English (en)
Korean (ko)
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최정아
임재현
김승환
허진
유선미
최장원
이령
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엘지전자 주식회사
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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
    • H04N19/12—Selection from among a plurality of transforms or standards, e.g. selection between discrete cosine transform [DCT] and sub-band transform or selection between H.263 and H.264
    • H04N19/122—Selection of transform size, e.g. 8x8 or 2x4x8 DCT; Selection of sub-band transforms of varying structure or type
    • 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
    • H04N19/124—Quantisation
    • 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
    • H04N19/132—Sampling, masking or truncation of coding units, e.g. adaptive resampling, frame skipping, frame interpolation or high-frequency transform coefficient masking
    • 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
    • H04N19/18—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 a set of transform coefficients
    • 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
    • H04N19/60—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using transform coding
    • H04N19/61—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using transform coding in combination with predictive coding
    • 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
    • H04N19/70—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals characterised by syntax aspects related to video coding, e.g. related to compression standards

Definitions

  • the present disclosure relates to image coding technology, and more particularly, to a method and apparatus for coding a transform coefficient level of transform coefficients in an image coding system.
  • VR Virtual Reality
  • AR Artificial Realtiy
  • holograms video/video having a video characteristic different from a real video such as a game video
  • video/video having a video characteristic different from a real video such as a game video
  • the broadcast for is increasing.
  • a high-efficiency video/video compression technology is required to effectively compress, transmit, store, and reproduce information of a high-resolution, high-quality video/video having various characteristics as described above.
  • the technical problem of the present disclosure is to provide a method and apparatus for improving image coding efficiency.
  • Another technical problem of the present disclosure is to provide a method and apparatus for increasing the efficiency of residual coding.
  • Another technical problem of the present disclosure is to provide a method and apparatus for improving coding efficiency of a transform coefficient level of transform coefficients.
  • Another technical problem of the present disclosure relates to a parity level flag for a parity of a transform coefficient level, a second transform coefficient level flag indicating whether a transform coefficient level is greater than a second threshold in syntax structure with respect to a specific transform coefficient.
  • a method and apparatus for reducing coding complexity and reducing delay by being coded in a pass such as a first transform coefficient level flag indicating whether a transform coefficient level is greater than a first threshold.
  • Another technical problem of the present disclosure is the number of valid coefficient flags for transform coefficients for the current block, indicating whether the transform coefficient level of each of the transform coefficients for the current block is a non-zero valid coefficient, the first transform coefficient level Disclosed is a method and apparatus for reducing coding complexity and reducing delay by limiting the sum of the number of flags, the number of second transform coefficient level flags, and the number of parity level flags to a predetermined threshold or less.
  • an image decoding method performed by a decoding apparatus comprises: receiving a bitstream including residual information, deriving quantized transform coefficients for a current block based on the residual information included in the bitstream, an inverse quantization process Deriving transform coefficients for the current block from the quantized transform coefficients based on ), and applying residual inverse transform to the derived transform coefficients to derive residual samples for the current block And generating a reconstructed picture based on the residual sample for the current block, wherein the transform coefficients for the current block are a first transform coefficient and a second transform coded after the first transform coefficient.
  • a coefficient, and the residual information includes: a first transform coefficient level flag for the first transform coefficient indicating whether the transform coefficient level of the first transform coefficient is greater than a first threshold, a conversion of the first transform coefficient A second transform coefficient level flag for the first transform coefficient indicating whether a coefficient level is greater than a second threshold, a second transform coefficient indicating whether the transform coefficient level of the second transform coefficient is greater than the first threshold A first transform coefficient level flag for the second transform coefficient level flag for the second transform coefficient indicating whether the transform coefficient level of the second transform coefficient is greater than the second threshold value, and wherein the second threshold value is
  • the step of deriving the quantized transform coefficients for the current block greater than a first threshold includes: the first transform coefficient level flag for the first transform coefficient, and the second transform coefficient level for the first transform coefficient Parsing the flag, the first transform coefficient level flag for the second transform coefficient and the second transform coefficient level flag for the second transform coefficient, and deriving the transform coefficients for the current block Step 1, the first transformation The first transform coefficient level flag for the coefficient, the second transform coefficient
  • a decoding apparatus for performing image decoding.
  • the decoding apparatus receives an bitstream including residual information, and an entropy decoding unit for deriving quantized transform coefficients for a current block based on the residual information included in the bitstream, an inverse quantization process (inverse an inverse quantization unit that derives transform coefficients for the current block from the quantized transform coefficients based on a quantization process, and applies a inverse transform to the derived transform coefficients, resulting in a residual sample for the current block An inverse transform unit for deriving them and an adder for generating a reconstructed picture based on the residual sample for the current block, wherein the transform coefficients for the current block are later than the first transform coefficient and the first transform coefficient.
  • a second transform coefficient to be coded comprising: a first transform coefficient level flag for the first transform coefficient indicating whether a transform coefficient level of the first transform coefficient is greater than a first threshold, the first A second transform coefficient level flag for the first transform coefficient indicating whether the transform coefficient level of one transform coefficient is greater than a second threshold, the transform coefficient level of the second transform coefficient is greater than the first threshold, A first transform coefficient level flag for a second transform coefficient and a second transform coefficient level flag for the second transform coefficient indicating whether the transform coefficient level of the second transform coefficient is greater than the second threshold, and wherein The second threshold is greater than the first threshold, and deriving the quantized transform coefficients for the current block performed by the entropy decoding unit includes: the first transform coefficient level flag for the first transform coefficient, Parsing the second transform coefficient level flag for the first transform coefficient, the first transform coefficient level flag for the second transform coefficient and the second transform coefficient level flag for the second transform coefficient.
  • the step of deriving the transform coefficients for the current block performed by the processor may include: the first transform coefficient level flag for the first transform coefficient, the second transform coefficient level flag for the first transform coefficient, and the And deriving the transform coefficients for the current block based on the first transform coefficient level flag for the second transform coefficient and the second transform coefficient level flag for the second transform coefficient, wherein the first transform coefficient is The second transform coefficient level flag for the transform coefficient is parsed before the first transform coefficient level flag for the second transform coefficient.
  • a video encoding method performed by an encoding device comprises: deriving residual samples for the current block, transforming the residual samples for the current block to derive transform coefficients for the current block, from the transform coefficients based on a quantization process Deriving quantized transform coefficients and encoding residual information including information about the quantized transform coefficients, wherein the transform coefficients for the current block include a first transform coefficient and the first transform coefficient.
  • a second transform coefficient that is coded later than a transform coefficient, and the residual information is a first transform coefficient level for the first transform coefficient indicating whether the transform coefficient level of the first transform coefficient is greater than a first threshold Flag, a second transform coefficient level flag for the first transform coefficient indicating whether the transform coefficient level of the first transform coefficient is greater than a second threshold, whether a transform coefficient level of the second transform coefficient is greater than the first threshold
  • a first transform coefficient level flag for the second transform coefficient indicating whether and a second transform coefficient level flag for the second transform coefficient indicating whether the transform coefficient level of the second transform coefficient is greater than the second threshold
  • the second threshold is greater than the first threshold, and encoding the residual information, based on the transform coefficients for the current block, the first transform coefficient level for the first transform coefficient Encoding a flag, the second transform coefficient level flag for the first transform coefficient, the first transform coefficient level flag for the second transform coefficient, and the second transform coefficient level flag for the second transform coefficient.
  • the second transform coefficient level flag for the first transform coefficient is encoded before the first transform coefficient
  • an encoding apparatus for performing video encoding.
  • the encoding apparatus includes a subtraction unit for deriving residual samples for the current block, a transformation unit for transforming the residual samples for the current block to derive transform coefficients for the current block, and the transformation based on a quantization process
  • a first transform coefficient level flag, a second transform coefficient level flag for the first transform coefficient indicating whether the transform coefficient level of the first transform coefficient is greater than a second threshold, and a transform coefficient level of the second transform coefficient are A first transform coefficient level flag for the second transform coefficient indicating whether it is greater than a first threshold
  • a decoder readable storage medium stores information about instructions that cause a video decoding apparatus to perform decoding methods according to some embodiments.
  • a decoder readable storage medium that stores information on instructions that cause a video decoding apparatus to perform a decoding method according to an embodiment.
  • the decoding method according to the embodiment may include receiving a bitstream including residual information, and deriving quantized transform coefficients for a current block based on the residual information included in the bitstream, inverse Deriving transform coefficients for the current block from the quantized transform coefficients based on an inverse quantization process, and applying an inverse transform to the derived transform coefficients to register the current block Deriving dual samples and generating a reconstructed picture based on the residual sample for the current block, wherein the transform coefficients for the current block are greater than the first transform coefficient and the first transform coefficient.
  • a second transform coefficient that is coded later, and the residual information includes: a first transform coefficient level flag for the first transform coefficient indicating whether the transform coefficient level of the first transform coefficient is greater than a first threshold, the A second transform coefficient level flag for the first transform coefficient indicating whether the transform coefficient level of the first transform coefficient is greater than a second threshold, and whether the transform coefficient level of the second transform coefficient is greater than the first threshold
  • the second threshold is greater than the first threshold
  • deriving the quantized transform coefficients for the current block includes: the first transform coefficient level flag for the first transform coefficient, and the first transform coefficient for the first transform coefficient.
  • the steps include: the first transform coefficient level flag for the first transform coefficient, the second transform coefficient level flag for the first transform coefficient, the first transform coefficient level flag for the second transform coefficient, and the first And deriving the transform coefficients for the current block based on the second transform coefficient level flag for the second transform coefficient, wherein the second transform coefficient level flag for the first transform coefficient is the second transform. It is characterized in that it is parsed before the first transform coefficient level flag for the coefficient.
  • the efficiency of residual coding can be increased.
  • coding efficiency of a transform coefficient level of transform coefficients can be increased.
  • a second transform coefficient level flag indicating whether a transform coefficient level is greater than a second threshold in syntax structure includes a parity level flag and a transform coefficient level for parity of the transform coefficient level. It is possible to reduce coding complexity and reduce delay by being coded in a pass such as a first transform coefficient level flag indicating whether it is greater than a first threshold.
  • the number of valid coefficient flags for transform coefficients for the current block the number of first transform coefficient level flags, indicating whether the transform coefficient level of each of the transform coefficients for the current block is a non-zero valid coefficient,
  • FIG. 1 schematically shows an example of a video/image coding system to which the present disclosure can be applied.
  • FIG. 2 is a diagram schematically illustrating a configuration of a video/video encoding apparatus to which the present disclosure can be applied.
  • FIG. 3 is a diagram schematically illustrating a configuration of a video/video decoding apparatus to which the present disclosure can be applied.
  • FIG. 4 is a block diagram of a CABAC encoding system according to an embodiment.
  • FIG. 5 is a diagram showing an example of transform coefficients in a 4x4 block.
  • FIG. 6 is a flowchart illustrating an operation of an encoding apparatus according to an embodiment.
  • FIG. 7 is a block diagram showing the configuration of an encoding apparatus according to an embodiment.
  • FIG. 8 is a flowchart illustrating an operation of a decoding apparatus according to an embodiment.
  • FIG. 9 is a block diagram showing the configuration of a decoding apparatus according to an embodiment.
  • FIG. 10 shows an example of a content streaming system to which the invention disclosed in this document can be applied.
  • an image decoding method performed by a decoding apparatus comprises: receiving a bitstream including residual information, deriving quantized transform coefficients for a current block based on the residual information included in the bitstream, an inverse quantization process Deriving transform coefficients for the current block from the quantized transform coefficients based on ), and applying residual inverse transform to the derived transform coefficients to derive residual samples for the current block And generating a reconstructed picture based on the residual sample for the current block, wherein the transform coefficients for the current block are a first transform coefficient and a second transform coded after the first transform coefficient.
  • a coefficient, and the residual information includes: a first transform coefficient level flag for the first transform coefficient indicating whether the transform coefficient level of the first transform coefficient is greater than a first threshold, a conversion of the first transform coefficient A second transform coefficient level flag for the first transform coefficient indicating whether a coefficient level is greater than a second threshold, a second transform coefficient indicating whether the transform coefficient level of the second transform coefficient is greater than the first threshold A first transform coefficient level flag for the second transform coefficient level flag for the second transform coefficient indicating whether the transform coefficient level of the second transform coefficient is greater than the second threshold value, and wherein the second threshold value is
  • the step of deriving the quantized transform coefficients for the current block greater than a first threshold includes: the first transform coefficient level flag for the first transform coefficient, and the second transform coefficient level for the first transform coefficient Parsing the flag, the first transform coefficient level flag for the second transform coefficient and the second transform coefficient level flag for the second transform coefficient, and deriving the transform coefficients for the current block Step 1, the first transformation The first transform coefficient level flag for the coefficient, the second transform coefficient
  • each configuration in the drawings described in the present disclosure is independently illustrated for convenience of description of different characteristic functions, and does not mean that each configuration is implemented with separate hardware or separate software.
  • two or more components of each component may be combined to form one component, or one component may be divided into a plurality of components.
  • Embodiments in which each configuration is integrated and/or separated are also included in the scope of the present disclosure without departing from the essence of the present disclosure.
  • FIG. 1 schematically shows an example of a video/image coding system to which the present disclosure can be applied.
  • VVC versatile video coding
  • EVC essential video coding
  • AV1 AOMedia Video 1
  • AVS2 2nd generation of audio video coding standard
  • next-generation video it can be applied to the method disclosed in the video coding standard (ex. H.267 or H.268, etc.).
  • video may refer to a set of images over time.
  • a picture generally refers to a unit representing one image in a specific time period, and a slice/tile is a unit constituting a part of a picture in coding.
  • the slice/tile may include one or more coding tree units (CTUs).
  • CTUs coding tree units
  • One picture may be composed of one or more slices/tiles.
  • One picture may be composed of one or more tile groups.
  • One tile group may include one or more tiles.
  • the brick may represent a rectangular region of CTU rows within a tile in a picture. Tiles can be partitioned into multiple bricks, and each brick can be composed of one or more CTU rows in the tile (A tile may be partitioned into multiple bricks, each of which consisting of one or more CTU rows within the tile ).
  • a tile that is not partitioned into multiple bricks may be also referred to as a brick.
  • a brick scan can indicate a specific sequential ordering of CTUs partitioning a picture, the CTUs can be aligned with a CTU raster scan within a brick, and bricks in a tile can be aligned sequentially with a raster scan of the bricks of the tile.
  • A, and tiles in a picture can be sequentially aligned with a raster scan of the tiles of the picture
  • a brick scan is a specific sequential ordering of CTUs partitioning a picture in which the CTUs are ordered consecutively in CTU raster scan in a brick , bricks within a tile are ordered consecutively in a raster scan of the bricks of the tile, and tiles in a picture are ordered consecutively in a raster scan of the tiles of the picture).
  • a tile is a rectangular region of CTUs within a particular tile column and a particular tile row in a picture.
  • the tile column is a rectangular area of CTUs, the rectangular area has a height equal to the height of the picture, and the width can be specified by syntax elements in a picture parameter set (The tile column is a rectangular region of CTUs having a height equal to the height of the picture and a width specified by syntax elements in the picture parameter set).
  • the tile row is a rectangular region of CTUs, the rectangular region has a width specified by syntax elements in a picture parameter set, and the height can be the same as the height of the picture (The tile row is a rectangular region of CTUs having a height specified by syntax elements in the picture parameter set and a width equal to the width of the picture).
  • a tile scan can indicate a specific sequential ordering of CTUs partitioning a picture, the CTUs can be successively aligned with a CTU raster scan in a tile, and the tiles in a picture can be successively aligned with a raster scan of the tiles of the picture.
  • a tile scan is a specific sequential ordering of CTUs partitioning a picture in which the CTUs are ordered consecutively in CTU raster scan in a tile whereas tiles in a picture are ordered consecutively in a raster scan of the tiles of the picture).
  • a slice may include an integer number of bricks of a picture, and the integer number of bricks may be included in one NAL unit (A slice includes an integer number of bricks of a picture that may be exclusively contained in a single NAL unit). A slice may consist of either a number of complete tiles or only a consecutive sequence of complete bricks of one tile ).
  • Tile groups and slices are used interchangeably in this document. For example, the tile group/tile group header in this document may be referred to as a slice/slice header.
  • a pixel or pel may mean a minimum unit constituting one picture (or image).
  • sample' may be used as a term corresponding to a pixel.
  • the sample may generally represent a pixel or a pixel value, may represent only a pixel/pixel value of a luma component, or may represent only a pixel/pixel value of a chroma component.
  • the unit may represent a basic unit of image processing.
  • the unit may include at least one of a specific region of a picture and information related to the region.
  • One unit may include one luma block and two chroma (ex. cb, cr) blocks.
  • the unit may be used interchangeably with terms such as a block or area depending on the case.
  • the MxN block may include samples (or sample arrays) of M columns and N rows or a set (or array) of transform coefficients.
  • a video/image coding system may include a first device (source device) and a second device (receiving device).
  • the source device may transmit the encoded video/image information or data to a receiving device through a digital storage medium or network in the form of a file or streaming.
  • the source device may include a video source, an encoding device, and a transmission unit.
  • the receiving device may include a receiving unit, a decoding apparatus, and a renderer.
  • the encoding device may be called a video/video encoding device, and the decoding device may be called a video/video decoding device.
  • the transmitter can be included in the encoding device.
  • the receiver may be included in the decoding device.
  • the renderer may include a display unit, and the display unit may be configured as a separate device or an external component.
  • the video source may acquire a video/image through a capture, synthesis, or generation process of the video/image.
  • the video source may include a video/image capture device and/or a video/image generation 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 capture process may be replaced by a process of generating related data.
  • the encoding device can encode the input video/video.
  • the encoding apparatus may perform a series of procedures such as prediction, transformation, and quantization for compression and coding efficiency.
  • the encoded data (encoded video/image information) may be output in the form of a bitstream.
  • the transmitting unit may transmit the encoded video/video information or data output in the form of a bitstream to a receiving unit of a receiving device through a digital storage medium or a network in a file or streaming format.
  • the digital storage media may include various storage media such as USB, SD, CD, DVD, Blu-ray, HDD, SSD.
  • the transmission unit 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 receiver may receive/extract the bitstream and deliver it to a decoding device.
  • the decoding apparatus 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 encoding apparatus.
  • the renderer can render the decoded video/image.
  • the rendered video/image may be displayed through the display unit.
  • the video encoding device may include a video encoding device.
  • the encoding apparatus 200 includes an image partitioner 210, a predictor 220, a residual processor 230, and an entropy encoder 240. It may be configured to include an adder (250), a filtering unit (filter, 260) and a memory (memory, 270).
  • the prediction unit 220 may include an inter prediction unit 221 and an intra prediction unit 222.
  • the residual processing unit 230 may include a transformer 232, a quantizer 233, a dequantizer 234, and an inverse transformer 235.
  • the residual processing unit 230 may further include a subtractor 231.
  • the adder 250 may be referred to as a reconstructor or a recontructged block generator.
  • the above-described image segmentation unit 210, prediction unit 220, residual processing unit 230, entropy encoding unit 240, adding unit 250, and filtering unit 260 may include one or more hardware components (for example, it may be configured by an encoder chipset or processor). Also, the memory 270 may include a decoded picture buffer (DPB), or may be configured by a digital storage medium. The hardware component may further include a memory 270 as an internal/external component.
  • DPB decoded picture buffer
  • the image division unit 210 may divide an input image (or picture, frame) input to the encoding apparatus 200 into one or more processing units.
  • the processing unit may be called a coding unit (CU).
  • the coding unit is recursively divided according to a quad-tree binary-tree ternary-tree (QTBTTT) structure from a coding tree unit (CTU) or a largest coding unit (LCU).
  • QTBTTT quad-tree binary-tree ternary-tree
  • CTU coding tree unit
  • LCU largest coding unit
  • 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 structure.
  • a quad tree structure may be applied first, and a binary tree structure and/or a ternary structure may be applied later.
  • a binary tree structure may be applied first.
  • the coding procedure according to the present disclosure can be performed based on the final coding unit that is no longer split.
  • the maximum coding unit may be directly used as a final coding unit based on coding efficiency according to image characteristics, or the coding unit may be recursively divided into coding units having a lower depth than optimal, if necessary.
  • the coding unit of the size of can be used as the final coding unit.
  • the coding procedure may include procedures such as prediction, transformation, and reconstruction, which will be described later.
  • the processing unit may further include a prediction unit (PU) or a transform unit (TU).
  • the prediction unit and the transform unit may be partitioned or partitioned from the above-described final coding unit, respectively.
  • the prediction unit may be a unit of sample prediction
  • the transformation unit may be a unit for deriving a transform coefficient and/or a unit for deriving a residual signal from the transform coefficient.
  • the unit may be used interchangeably with terms such as a block or area depending on the case.
  • the MxN block may represent samples of M columns and N rows or a set of transform coefficients.
  • the sample may generally represent a pixel or a pixel value, and may indicate only a pixel/pixel value of a luma component or only a pixel/pixel value of a saturation component.
  • the sample may be used as a term for one picture (or image) corresponding to a pixel or pel.
  • the encoding device 200 subtracts a prediction signal (a predicted block, a prediction sample array) output from the inter prediction unit 221 or the intra prediction unit 222 from the input image signal (original block, original sample array).
  • a signal residual signal, residual block, residual sample array
  • the generated residual signal is transmitted to the conversion unit 232.
  • a unit for subtracting a prediction signal (a prediction block, a prediction sample array) from an input image signal (original block, original sample array) in the encoder 200 may be referred to as a subtraction unit 231.
  • the prediction unit may perform prediction on a block to be processed (hereinafter, referred to as a current block) and generate a predicted block including prediction samples for the current block.
  • the prediction unit may determine whether intra prediction is applied to the current block or CU or inter prediction is applied. As described later in the description of each prediction mode, the prediction unit may generate various information about prediction, such as prediction mode information, and transmit it to the entropy encoding unit 240.
  • the prediction information may be encoded by the entropy encoding unit 240 and output in the form of a bitstream.
  • the intra prediction unit 222 may predict the current block by referring to samples in the current picture.
  • the referenced samples may be located in the neighbor of the current block or may be located apart depending on a prediction mode.
  • 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 according to 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 222 may determine a prediction mode applied to the current block using a prediction mode applied to neighboring blocks.
  • the inter prediction unit 221 may derive the 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 the correlation of 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 present in the current picture and a temporal neighboring block present in the reference picture.
  • the reference picture including the reference block and the reference picture including the temporal neighboring block may be the same or different.
  • the temporal neighboring block may be referred to by a name such as a collocated reference block or a colCU, and a reference picture including the temporal neighboring block may be called a collocated picture (colPic).
  • the inter prediction unit 221 constructs a motion information candidate list based on neighboring blocks, and provides information indicating which candidates are used to derive the motion vector and/or reference picture index of the current block. Can be created. Inter prediction may be performed based on various prediction modes. For example, in the case of the skip mode and the merge mode, the inter prediction unit 221 may use motion information of neighboring blocks as motion information of the current block.
  • the residual signal may not be transmitted.
  • the motion vector of the current block is obtained by using the motion vector of the neighboring block as a motion vector predictor and signaling a motion vector difference. I can order.
  • the prediction unit 220 may generate a prediction signal based on various prediction methods described below.
  • the prediction unit may apply intra prediction or inter prediction as well as intra prediction and inter prediction at the same time for prediction for one block. This can be called combined inter and intra prediction (CIIP).
  • the prediction unit may be based on an intra block copy (IBC) prediction mode or a palette mode for prediction of a block.
  • the IBC prediction mode or palette mode may be used for content video/video coding such as a game, such as screen content coding (SCC).
  • SCC screen content coding
  • IBC basically performs prediction in the current picture, but can be performed similarly to inter prediction in that a reference block is derived in the current picture. That is, the IBC can use at least one of the inter prediction techniques described in this document.
  • the palette mode can be regarded as an example of intra coding or intra prediction. When the palette mode is applied, a sample value in a picture may be signaled based on information on the palette table and palette index.
  • 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 transform unit 232 may generate transform coefficients by applying a transform technique to the residual signal. For example, at least one of a DCT (Discrete Cosine Transform), DST (Discrete Sine Transform), KLT (Karhunen-Loeve Transform), GBT (Graph-Based Transform), or CNT (Conditionally Non-linear Transform) It can contain.
  • GBT refers to a transformation obtained from this graph when it is said to graphically represent relationship information between pixels.
  • CNT means a transform obtained by generating a prediction signal using all previously reconstructed pixels and based on it.
  • the transform process may be applied to pixel blocks having the same size of a square, or may be applied to blocks of variable sizes other than squares.
  • the quantization unit 233 quantizes the transform coefficients and transmits them to the entropy encoding unit 240, and the entropy encoding unit 240 encodes a quantized signal (information about quantized transform coefficients) and outputs it as a bitstream. have. Information about the quantized transform coefficients may be referred to as residual information.
  • the quantization unit 233 may rearrange block-type quantized transform coefficients into a one-dimensional vector form based on a coefficient scan order, and quantize the quantized transform coefficients based on the one-dimensional vector form. Information regarding transform coefficients may be generated.
  • the entropy encoding unit 240 may perform various encoding methods such as exponential Golomb (CAVLC), context-adaptive variable length coding (CAVLC), and context-adaptive binary arithmetic coding (CABAC).
  • CAVLC exponential Golomb
  • CAVLC context-adaptive variable length coding
  • CABAC context-adaptive binary arithmetic coding
  • the entropy encoding unit 240 may encode information necessary for video/image reconstruction (eg, a value of syntax elements, etc.) together with the quantized transform coefficients together or separately.
  • the encoded information (ex. encoded video/video information) may be transmitted or stored in units of network abstraction layer (NAL) units in the form of a bitstream.
  • NAL network abstraction layer
  • the video/image information may further include information regarding 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/image information may further include general constraint information.
  • information and/or syntax elements transmitted/signaled from an encoding device to a decoding device may be included in video/video information.
  • the video/video information may be encoded through the above-described encoding procedure and included in the bitstream.
  • the bitstream can be transmitted over a network or stored on 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, SSD.
  • the signal output from the entropy encoding unit 240 may be configured as an internal/external element of the encoding device 200 by a transmitting unit (not shown) and/or a storing unit (not shown) for storing, or the transmitting unit It may be included in the entropy encoding unit 240.
  • the quantized transform coefficients output from the quantization unit 233 may be used to generate a prediction signal.
  • a residual signal residual block or residual samples
  • the adder 155 adds the reconstructed residual signal to the predicted signal output from the inter predictor 221 or the intra predictor 222, so that the reconstructed signal (restored picture, reconstructed block, reconstructed sample array) Can be generated. If there is no residual for the block to be processed, such as when the skip mode is applied, the predicted block may be used as a reconstructed block.
  • the adder 250 may be called a restoration unit or a restoration block generation unit.
  • the generated reconstructed signal may be used for intra prediction of a next processing target block in a current picture, or may be used for inter prediction of a next picture through filtering as described below.
  • LMCS luma mapping with chroma scaling
  • the filtering unit 260 may apply subjective/objective filtering to improve subjective/objective image quality.
  • the filtering unit 260 may generate a modified restoration picture by applying various filtering methods to the restoration picture, and the modified restoration picture may be a DPB of the memory 270, specifically, the memory 270. Can be stored in.
  • the various filtering methods may include, for example, deblocking filtering, sample adaptive offset, adaptive loop filter, bilateral filter, and the like.
  • the filtering unit 260 may generate various information regarding filtering as described later in the description of each filtering method, and transmit the generated information to the entropy encoding unit 240.
  • the filtering information may be encoded by the entropy encoding unit 240 and output in the form of a bitstream.
  • the modified reconstructed picture transmitted to the memory 270 may be used as a reference picture in the inter prediction unit 221.
  • inter prediction When the inter prediction is applied through the encoding apparatus, prediction mismatch between the encoding apparatus 100 and the decoding apparatus can be avoided, and encoding efficiency can be improved.
  • the memory 270 DPB may store the modified reconstructed picture for use as a reference picture in the inter prediction unit 221.
  • the memory 270 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 has already been reconstructed.
  • the stored motion information may be transmitted to the inter prediction unit 221 to be used as motion information of a spatial neighboring block or motion information of a temporal neighboring block.
  • the memory 270 may store reconstructed samples of blocks reconstructed in the current picture, and may transmit the reconstructed samples to the intra prediction unit 222.
  • FIG. 3 is a diagram schematically illustrating a configuration of a video/video decoding apparatus to which the present disclosure can be applied.
  • the decoding apparatus 300 includes an entropy decoder (310), a residual processor (320), a prediction unit (predictor, 330), an adder (340), and a filtering unit (filter, 350) and memory (memoery, 360).
  • the prediction unit 330 may include an inter prediction unit 331 and an intra prediction unit 332.
  • the residual processing unit 320 may include a deequantizer (321) and an inverse transformer (321).
  • the entropy decoding unit 310, the residual processing unit 320, the prediction unit 330, the adding unit 340, and the filtering unit 350 described above may include one hardware component (eg, a decoder chipset or processor) according to an embodiment. ).
  • the memory 360 may include a decoded picture buffer (DPB), or may be configured by a digital storage medium.
  • the hardware component may further include a memory 360 as an internal/external component.
  • the decoding apparatus 300 may restore an image corresponding to a process in which the video/image information is processed in the encoding apparatus of FIG. 2.
  • the decoding apparatus 300 may derive units/blocks based on block partitioning related information obtained from the bitstream.
  • the decoding apparatus 300 may perform decoding using a processing unit applied in the encoding apparatus.
  • the processing unit of decoding may be, for example, a coding unit, and the coding unit may be divided along a quad tree structure, a binary tree structure and/or a ternary tree structure from a coding tree unit or a largest coding unit.
  • One or more transform units can be derived from the coding unit. Then, the decoded video signal decoded and output through the decoding device 300 may be reproduced through the reproduction device.
  • the decoding apparatus 300 may receive the signal output from the encoding apparatus of FIG. 2 in the form of a bitstream, and the received signal may be decoded through the entropy decoding unit 310.
  • the entropy decoding unit 310 may parse the bitstream to derive information (eg, video/image information) necessary for image reconstruction (or picture reconstruction).
  • the video/image information may further include information regarding 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/image information may further include general constraint information.
  • the decoding apparatus may decode a picture further based on the information on the parameter set and/or the general restriction information.
  • Signaling/receiving information and/or syntax elements described later in this document may be decoded through the decoding procedure and obtained from the bitstream.
  • the entropy decoding unit 310 decodes information in a bitstream based on a coding method such as exponential Golomb coding, CAVLC, or CABAC, and quantizes a value of a syntax element required for image reconstruction and a transform coefficient for residual.
  • a coding method such as exponential Golomb coding, CAVLC, or CABAC
  • the CABAC entropy decoding method receives bins corresponding to each syntax element in a bitstream, and decodes syntax element information to be decoded and decoding information of neighboring and decoded blocks or symbol/bin information decoded in the previous step.
  • the context model is determined by using, and the probability of occurrence of the bin is predicted according to the determined context model, and arithmetic decoding of the bin is performed to generate a symbol corresponding to the value of each syntax element. have.
  • the CABAC entropy decoding method may update the context model using the decoded symbol/bin information for the next symbol/bin context model after determining the context model.
  • prediction information is provided to a prediction unit (inter prediction unit 332 and intra prediction unit 331), and the entropy decoding unit 310 performs entropy decoding.
  • the dual value, that is, quantized transform coefficients and related parameter information may be input to the residual processor 320.
  • the residual processing unit 320 may derive a residual signal (residual block, residual samples, residual sample array). Also, information related to filtering among information decoded by the entropy decoding unit 310 may be provided to the filtering unit 350. Meanwhile, a receiving unit (not shown) receiving a signal output from the encoding device may be further configured as an internal/external element of the decoding device 300, or the receiving unit may be a component of the entropy decoding unit 310.
  • the decoding device may be called a video/picture/picture decoding device, and the decoding device may be classified into an information decoder (video/picture/picture information decoder) and a sample decoder (video/picture/picture sample decoder). It might be.
  • the information decoder may include the entropy decoding unit 310, and the sample decoder may include the inverse quantization unit 321, an inverse transformation unit 322, an addition unit 340, a filtering unit 350, and a memory 360 ), at least one of an inter prediction unit 332 and an intra prediction unit 331.
  • the inverse quantization unit 321 may inverse quantize the quantized transform coefficients to output transform coefficients.
  • the inverse quantization unit 321 may rearrange the quantized transform coefficients in a two-dimensional block form. In this case, the reordering may be performed based on the coefficient scan order performed by the encoding device.
  • the inverse quantization unit 321 may perform inverse quantization on the quantized transform coefficients by using a quantization parameter (for example, quantization step size information), and obtain transform coefficients.
  • a quantization parameter for example, quantization step size information
  • the inverse transform unit 322 inversely transforms the 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 information about the prediction output from the entropy decoding unit 310, and may determine a specific intra/inter prediction mode.
  • the prediction unit 320 may generate a prediction signal based on various prediction methods described below.
  • the prediction unit may apply intra prediction or inter prediction as well as intra prediction and inter prediction at the same time for prediction for one block. This can be called combined inter and intra prediction (CIIP).
  • the prediction unit may be based on an intra block copy (IBC) prediction mode or a palette mode for prediction of a block.
  • the IBC prediction mode or palette mode may be used for content video/video coding such as a game, such as screen content coding (SCC).
  • SCC screen content coding
  • IBC basically performs prediction in the current picture, but can be performed similarly to inter prediction in that a reference block is derived in the current picture. That is, the IBC can use at least one of the inter prediction techniques described in this document.
  • the palette mode can be regarded as an example of intra coding or intra prediction. When the pallet mode is applied, information on the pallet table and pallet index may be included in the video/image information and signaled.
  • the intra prediction unit 331 may predict the current block by referring to samples in the current picture.
  • the referenced samples may be located in the neighbor of the current block or may be located apart depending on a prediction mode.
  • prediction modes may include a plurality of non-directional modes and a plurality of directional modes.
  • the intra prediction unit 331 may determine a prediction mode applied to the current block using a prediction mode applied to neighboring blocks.
  • the inter prediction unit 332 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 the correlation of 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 present in the current picture and a temporal neighboring block present in the reference picture.
  • the inter prediction unit 332 may construct a motion information candidate list based on neighboring blocks, and derive a motion vector and/or reference picture index of the current block based on the received candidate selection information.
  • Inter prediction may be performed based on various prediction modes, and information on the prediction may include information indicating a mode of inter prediction for the current block.
  • the adding unit 340 reconstructs the obtained residual signal by adding it to the prediction signal (predicted block, prediction sample array) output from the prediction unit (including the inter prediction unit 332 and/or the intra prediction unit 331).
  • a signal (restored picture, reconstructed block, reconstructed sample array) can be generated. If there is no residual for the block to be processed, such as when the skip mode is applied, the predicted block may be used as a reconstructed block.
  • the adding unit 340 may be called a restoration unit or a restoration block generation unit.
  • the generated reconstructed signal may be used for intra prediction of a next processing target block in a current picture, may be output through filtering as described below, or may be used for inter prediction of a next picture.
  • LMCS luma mapping with chroma scaling
  • the filtering unit 350 may improve subjective/objective image quality by applying filtering to the reconstructed signal.
  • the filtering unit 350 may generate a modified reconstructed picture by applying various filtering methods to the reconstructed picture, and the modified reconstructed picture may be a DPB of the memory 360, specifically, the memory 360 Can be transferred to.
  • the various filtering methods may include, for example, deblocking filtering, sample adaptive offset, adaptive loop filter, bilateral filter, and the like.
  • the (corrected) reconstructed picture stored in the DPB of the memory 360 may be used as a reference picture in the inter prediction unit 332.
  • the memory 360 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 has 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 360 may store reconstructed samples of blocks reconstructed in the current picture, and may transmit the reconstructed samples to the intra prediction unit 331.
  • the embodiments described in the filtering unit 260, the inter prediction unit 221, and the intra prediction unit 222 of the encoding device 100 are respectively the filtering unit 350 and the inter prediction of the decoding device 300.
  • the unit 332 and the intra prediction unit 331 may be applied to the same or corresponding.
  • a predicted block including prediction samples for a current block which is a block to be coded
  • the predicted block includes prediction samples in a spatial domain (or pixel domain).
  • the predicted block is derived equally from an encoding device and a decoding device, and the encoding device decodes information (residual information) about the residual between the original block and the predicted block, not the original sample value itself of the original block. Signaling to the device can improve video coding efficiency.
  • the decoding apparatus may derive a residual block including residual samples based on the residual information, and combine the residual block and the predicted block to generate a reconstructed block including reconstructed samples, and reconstruct the reconstructed blocks. It is possible to generate a reconstructed picture that includes.
  • the residual information may be generated through transformation and quantization procedures.
  • the encoding device derives a residual block between the original block and the predicted block, and derives transformation coefficients by performing a transformation procedure on residual samples (residual sample array) included in the residual block And, by performing a quantization procedure on the transform coefficients, the quantized transform coefficients are derived to signal related residual information (via a bitstream) to a decoding apparatus.
  • the residual information may include information such as value information of the quantized transform coefficients, location information, a transform technique, a transform kernel, and quantization parameters.
  • the decoding apparatus may perform an inverse quantization/inverse transformation procedure based on the residual information and derive residual samples (or residual blocks).
  • the decoding apparatus may generate a reconstructed picture based on the predicted block and the residual block.
  • the encoding device may also dequantize/inverse transform quantized transform coefficients for reference for inter prediction of a picture to derive a residual block, and generate a reconstructed picture based thereon.
  • FIG. 4 is a block diagram of a CABAC encoding system according to an embodiment.
  • CABAC CABAC for encoding a single syntax element.
  • the input signal when the input signal is a syntax element rather than a binary value, the input signal may be converted to a binary value through binarization. If the input signal is already binary, it can be bypassed without going through binarization.
  • each binary 0 or 1 constituting a binary value may be referred to as a bin.
  • each of 1, 1, and 0 when the binary string after binarization is 110, each of 1, 1, and 0 may be referred to as one bin.
  • Binary bins may be input to a regular encoding engine or a bypass encoding engine.
  • the regular encoding engine may allocate a context model (or context model) reflecting a probability value for the bin, and encode the bin based on the assigned context model.
  • the probability model for the bin can be updated.
  • These encoded bins are called context-coded bins.
  • the bypass encoding engine may omit the procedure of estimating the probability of the input bin and the procedure of updating the probability model applied to the bin after encoding. Instead of allocating context, it is possible to improve the encoding speed by encoding the input bin by applying a uniform probability distribution.
  • the bins thus coded may be referred to as bypass bins.
  • Entropy encoding may determine whether to perform encoding through a regular encoding engine or to perform encoding through a bypass encoding engine, and may switch encoding paths. Entropy decoding can be performed in the same order as encoding.
  • the (quantized) transformation coefficients are coded based on the syntax elements such as transform_skip_flag, last_sig_coeff_x_prefix, last_sig_coeff_y_prefix, last_sig_coeff_x_suffix, last_sig_coeff_y_suffix, coded_sub_block_flag, sig_coeff_flag, par_level_flag, rem_abs_gt1_flag, rem_abs_gt2_flag, abs_remainder, coeff_sign_flag, mts_idx (syntax elements) And/or decrypted. Table 1 below shows syntax elements related to residual data encoding.
  • transform_skip_flag indicates whether transform is omitted in an associated block.
  • the associated block may be a coding block (CB) or a transform block (TB).
  • CB and TB can be mixed.
  • residual samples are derived for CB, and (quantized) transform coefficients can be derived through transformation and quantization of the residual samples, through the residual coding procedure.
  • Information eg, syntax elements
  • the quantized transform coefficients can simply be called transform coefficients.
  • the size of the CB may be the same as the size of the TB, and in this case, the target block to be transformed (and quantized) and residual coded may be called CB or TB.
  • the target block to be transformed (and quantized) and residual coded may be called TB.
  • syntax elements related to residual coding are described as being signaled in units of a transform block (TB), but as an example, the TB may be mixed with a coding block (CB) as described above.
  • (x, y) position information of the last non-zero transform coefficient in a transform block may be encoded based on the syntax elements last_sig_coeff_x_prefix, last_sig_coeff_y_prefix, last_sig_coeff_x_suffix, and last_sig_coeff_y_suffix.
  • last_sig_coeff_x_prefix represents the prefix of the column position of the last significant coefficient in the scan order in the transform block
  • last_sig_coeff_y_prefix is the scan in the transform block
  • the prefix of the row position of the last significant coefficient in the scanning order, and last_sig_coeff_x_suffix is the last in the scanning order in the transform block
  • last_sig_coeff_y_suffix is the row of the last significant coefficient in the scanning order in the transform block Represents the suffix of the row position.
  • the effective coefficient may represent the non-zero coefficient.
  • the scan order may be a diagonal upward scan order.
  • the scan order may be a horizontal scan order or a vertical scan order.
  • the scan order may be determined based on whether intra/inter prediction is applied to a target block (CB or CB including TB) and/or a specific intra/inter prediction mode.
  • a 1-bit syntax element coded_sub_block_flag for each 4x4 sub-block may be used to indicate whether a non-zero coefficient exists in the current sub-block.
  • coded_sub_block_flag If the value of coded_sub_block_flag is 0, since there is no more information to transmit, the encoding process for the current subblock can be ended. Conversely, if the value of coded_sub_block_flag is 1, the encoding process for sig_coeff_flag can be continuously performed. Since the subblock containing the last non-zero coefficient does not require encoding for coded_sub_block_flag, and the subblock containing the DC information of the transform block has a high probability of including the nonzero coefficient, coded_sub_block_flag is not encoded and its value This can be assumed to be 1.
  • sig_coeff_flag having a binary value may be encoded according to the reversed order.
  • a 1-bit syntax element sig_coeff_flag can be encoded for each coefficient according to the scan order. If the value of the transform coefficient at the current scan position is not 0, the value of sig_coeff_flag may be 1.
  • the encoding process for the sub-block may be omitted.
  • Level information encoding can be performed only when sig_coeff_flag is 1, and four syntax elements can be used in the level information encoding process. More specifically, each sig_coeff_flag[xC][yC] may indicate whether the level (value) of the corresponding transform coefficient at each transform coefficient position (xC, yC) in the current TB is non-zero. In one embodiment, sig_coeff_flag may correspond to an example of a valid coefficient flag indicating whether the quantized transform coefficient is a valid coefficient other than 0.
  • Equation 1 The remaining level value after encoding for sig_coeff_flag may be equal to Equation 1 below. That is, the syntax element remAbsLevel indicating the level value to be encoded may be equal to Equation 1 below.
  • coeff means the actual transform coefficient value.
  • par_level_flag As shown in Equation 2 below, a least significant coefficient (LSB) value of remAbsLevel described in Equation 1 may be encoded.
  • par_level_flag[n] may indicate parity of the transform coefficient level (value) at the scanning position n.
  • the transform coefficient level value remAbsLevel to be encoded may be updated as shown in Equation 3 below.
  • par_level_flag remAbsLevel & 1
  • rem_abs_gt1_flag may indicate whether remAbsLevel' at the corresponding scanning position n is greater than 1
  • rem_abs_gt2_flag indicates whether remAbsLevel' at the corresponding scanning position n is greater than 2.
  • the encoding for abs_remainder can be performed only when rem_abs_gt2_flag is 1.
  • the sign of each coefficient can be coded using a 1-bit symbol coeff_sign_flag.
  • represents the transform coefficient level (value), and may be expressed as AbsLevel for the transform coefficient.
  • the par_level_flag represents an example of a parity level flag indicating the parity of the transform coefficient level of the transform coefficient
  • the rem_abs_gt1_flag is the first transform coefficient for whether the transform coefficient level of the transform coefficient is greater than a first threshold
  • An example of the level flag is shown, and the rem_abs_gt2_flag or rem_abs_gt3_flag may represent an example of the second transform coefficient level flag as to whether the transform coefficient level of the transform coefficient is greater than a second threshold.
  • the first transform coefficient level flag may be represented by abs_level_gt1_flag
  • the second transform coefficient level flag may be represented by abs_level_gt3_flag or abs_level_gt2_flag.
  • rem_abs_gt1_flag and rem_abs_gt2_flag may appear based on abs_level_gtx_flag[n][j].
  • abs_level_gtx_flag[n][j] may be a flag indicating whether an absolute value of a transform coefficient level (or a value obtained by shifting the transform coefficient level by 1 to the right) at scanning position n is greater than (j ⁇ 1)+1. .
  • the rem_abs_gt1_flag may perform the same and/or similar functions as abs_level_gtx_flag[n][0], and the rem_abs_gt2_flag may perform the same and/or similar functions as abs_level_gtx_flag[n][1]. That is, the abs_level_gtx_flag[n][0] may correspond to an example of the first transform coefficient level flag, and the abs_level_gtx_flag[n][1] may correspond to an example of the second transform coefficient level flag. have. In some cases, (j ⁇ 1)+1 may be replaced with a predetermined threshold, such as a first threshold and a second threshold.
  • FIG. 5 is a diagram showing an example of transform coefficients in a 4x4 block.
  • the 4x4 block of FIG. 5 shows an example of quantized coefficients.
  • the block illustrated in FIG. 5 may be a 4x4 transform block or a 4x4 subblock of 8x8, 16x16, 32x32, and 64x64 transform blocks.
  • the 4x4 block of FIG. 5 may represent a luminance block or a color difference block.
  • the encoding result of the inverse diagonally scanned coefficients of FIG. 5 may be as shown in Table 3, for example.
  • scan_pos indicates the position of the coefficient according to the inverse diagonal scan.
  • scan_pos 15 is the coefficient of the bottom right corner that is scanned first in the 4x4 block
  • scan_pos 0 represents the coefficient of the top left corner that is scanned last.
  • the scan_pos may be referred to as a scan position.
  • scan_pos 0 may be referred to as scan position 0.
  • 4x4 sub-block unit main syntax elements may include sig_coeff_flag, par_level_flag, rem_abs_gt1_flag, rem_abs_gt2_flag, abs_remainder, coeff_sign_flag, and the like.
  • sig_coeff_flag, par_level_flag, rem_abs_gt1_flag, and rem_abs_gt2_flag can represent context encoding bins that are encoded using a regular encoding engine (that is, context-based coding is applied), and abs_remainder and coeff_sign_flag are bypass encoding engines. Can be used to indicate the bypass bin to be encoded.
  • a valid coefficient flag eg, sig_coeff_flag
  • a first transform coefficient level flag eg, abs_level_gt1_flag or abs_level_gtx_flag[n) based on a repetition statement (eg, for statement, etc.) ][0], where n is an integer
  • the second transform coefficient level flag for example, abs_level_gt3_flag or abs_level_gtx_flag[n][1], where n is an integer
  • up to 28 bins may be allocated for a 4x4 sub-block, and up to 6 bins may be allocated for a 2x2 sub-block.
  • up to 4 bins may be allocated for a 4x4 sub-block, and up to 2 bins may be allocated for a 2x2 sub-block.
  • Bypass bins may be derived based on bypass coding in relation to the third for statement and the fourth for statement.
  • the first transform coefficient level flags, the parity level flags and the second transform coefficient level flags may be included in one for statement in syntax to form one pass. have. Examples for this embodiment may be as shown in Table 6 or Table 7 below.
  • up to K bins may be allocated for a 4x4 sub-block, and up to L bins may be allocated for a 2x2 sub-block.
  • Context-encoded bins can exhibit high data dependencies because they use the updated probability state and range while processing the previous bins. That is, parallel encoding may be difficult for the context-encoded bean since encoding/decoding of the current bin can be performed after encoding/decoding of the current bin is performed. In addition, it may take a long time to read the probability interval and determine the current state. Accordingly, in one embodiment, a method of improving CABAC throughput by reducing the number of context-encoding bins and increasing the number of bypass bins may be proposed.
  • coefficient level information may be encoded in an inverse scan order. That is, it can be encoded after being scanned in the upper left direction starting from the coefficients in the lower right of the unit block.
  • the count level that is first scanned in the reverse scan order may indicate a small value.
  • signaling par_level_flag, rem_abs_gt1_flag, and rem_abs_gt2_flag may not help to improve compression performance.
  • par_level_flag, rem_abs_gt1_flag, and rem_abs_gt2_flag may decrease encoding efficiency.
  • the context encoding bins are quickly switched to the abs_remainder syntax element encoded by the bypass encoding engine, that is, encoded by the bypass encoding engine (par_level_flag, rem_abs_gt1_flag, rem_abs_gt2_flag).
  • the number can be reduced.
  • K may have a value of 0 to 48.
  • rem_abs_gt2_flag may also not be encoded.
  • Table 9 shows an example when K is determined to be 30.
  • a method of limiting the sum of the numbers of sig_coeff_flag, par_level_flag, and rem_abs_gt1_flag and a method of limiting the number of rem_abs_gt2_flag described above may be combined.
  • K may have a value from 0 to 48
  • N may have a value from 0 to 16.
  • Table 10 shows a case in which K is limited to 30 and N is limited to 2.
  • K may vary according to the size of the subblock. .
  • K can have an integer value of one of the integers from 0 to 64, and when the size of the sub-block is 2x2, K is one of the integers from 0 to 16 It can have an integer value of. Table 11 below shows another example of the case where the K is determined as 30 in the encoding process for the 4x4 sub-block as shown in FIG.
  • FIG. 6 is a flowchart illustrating an operation of an encoding device according to an embodiment
  • FIG. 7 is a block diagram showing a configuration of an encoding device according to an embodiment.
  • the encoding device according to FIGS. 6 and 7 may perform operations corresponding to the decoding device according to FIGS. 8 and 9. Accordingly, the operations of the decoding device to be described later in FIGS. 8 and 9 can be applied to the encoding device according to FIGS. 6 and 7 as well.
  • Each step disclosed in FIG. 6 may be performed by the encoding apparatus 200 disclosed in FIG. 2. More specifically, S600 may be performed by the subtraction unit 231 illustrated in FIG. 2, S610 may be performed by the conversion unit 232 illustrated in FIG. 2, and S620 may be performed by the quantization unit 233 illustrated in FIG. 2. ), and S630 may be performed by the entropy encoding unit 240 illustrated in FIG. 2.
  • the operations according to S600 to S630 are based on some of the contents described in FIGS. 4 and 5. Accordingly, detailed descriptions that overlap with those described above in FIGS. 2, 4, and 5 will be omitted or simplified.
  • the encoding apparatus may include a subtraction unit 231, a conversion unit 232, a quantization unit 233, and an entropy encoding unit 240.
  • the encoding device may be implemented by more or less components than those shown in FIG. 7.
  • the subtraction unit 231, the conversion unit 232, the quantization unit 233, and the entropy encoding unit 240 may be implemented as separate chips, or at least two or more components may be used. It can also be implemented through a single chip.
  • the encoding apparatus may derive residual samples for the current block (S600). More specifically, the subtraction unit 231 of the encoding device may derive residual samples for the current block.
  • the encoding apparatus may transform the residual samples for the current block to derive transform coefficients for the current block (S610). More specifically, the conversion unit 232 of the encoding device may convert the residual samples for the current block to derive conversion coefficients for the current block.
  • the encoding apparatus may derive quantized transform coefficients from the transform coefficients based on a quantization process (S620). More specifically, the quantization unit 233 of the encoding apparatus may derive quantized transform coefficients from the transform coefficients based on a quantization process.
  • the encoding apparatus may encode residual information including information about the quantized transform coefficients (S630). More specifically, the entropy encoding unit 240 of the encoding device may encode residual information including information about the quantized transform coefficients.
  • the transform coefficients for the current block may include a first transform coefficient and a second transform coefficient coded later than the first transform coefficient.
  • the residual information includes a first transform coefficient level flag for the first transform coefficient indicating whether the transform coefficient level of the first transform coefficient is greater than a first threshold, and a transform coefficient level of the first transform coefficient is second.
  • a level flag and a second transform coefficient level flag for the second transform coefficient indicating whether the transform coefficient level of the second transform coefficient is greater than the second threshold may be included.
  • the second threshold may be greater than the first threshold.
  • Encoding apparatus encoding the residual information, the first transform coefficient level flag for the first transform coefficient, the first transform coefficient based on the transform coefficients for the current block And encoding the second transform coefficient level flag for, the first transform coefficient level flag for the second transform coefficient, and the second transform coefficient level flag for the second transform coefficient.
  • the second transform coefficient level flag for the first transform coefficient may be encoded before the first transform coefficient level flag for the second transform coefficient.
  • the residual information includes a parity level flag for the first transform coefficient indicating the parity of the transform coefficient level of the first transform coefficient and the transform coefficient level of the second transform coefficient.
  • a parity level flag for the second transform coefficient indicating parity may be further included.
  • the second transform coefficient level flag for the first transform coefficient may be encoded before the parity level flag for the second transform coefficient.
  • the second transform coefficient level flag for the first transform coefficient is encoded before the first transform coefficient level flag for the second transform coefficient, and the first transform for the second transform coefficient
  • the coefficient level flag may be encoded before the parity level flag for the second transform coefficient.
  • the first transform coefficient level flag for the first transform coefficient is encoded before the parity level flag for the first transform coefficient, and the parity level flag for the first transform coefficient is the first transform coefficient.
  • the first transform coefficient level flag for the first transform coefficient is encoded before the second transform coefficient level flag for the first transform coefficient, and the second transform coefficient level flag for the first transform coefficient is encoded before the first transform coefficient level flag for the second transform coefficient.
  • the first transform coefficient level flag for the second transform coefficient is encoded before the parity level flag for the second transform coefficient, and the parity level flag for the second transform coefficient is assigned to the second transform coefficient. For the second transform coefficient level flag.
  • the residual information comprises: the transform for the current block including the first transform coefficient level flag for the first transform coefficient and the first transform coefficient level flag for the second transform coefficient.
  • the second transform coefficient level flags for the transform coefficients for, the transform for the current block including the parity level flag for the first transform coefficient and the parity level flag for the second transform coefficient A validity coefficient flag for the transform coefficients for the current block, including parity level flags for the coefficients, and indicating whether the transform coefficient level of each of the transform coefficients for the current block is a non-zero valid coefficient.
  • the sum of the number of first transform coefficient level flags, the number of second transform coefficient level flags, the number of parity level flags, and the number of valid coefficient flags may be less than or equal to a predetermined threshold.
  • the predetermined threshold is determined as a first threshold, and based on the determination that the size of the current block is a 2x2 block size, the predetermined The threshold may be determined as a second threshold.
  • context-based coding may be applied to the first transform coefficient level flags, the second transform coefficient level flags, the parity level flags, and the effective coefficient flags.
  • the encoding apparatus derives residual samples for the current block (S600), converts the residual samples for the current block, and converts the residual samples to the current block.
  • the second transform coefficient level flag for the second transform coefficient indicating whether the second threshold value is greater than or equal to the second threshold value, wherein the second threshold value is greater than the first threshold value, and encoding the residual information includes: Based on the transform coefficients
  • coding efficiency of a transform coefficient level of transform coefficients can be increased.
  • a parity level flag and a transform coefficient for a parity of a transform coefficient level include a second transform coefficient level flag indicating whether a transform coefficient level is greater than a second threshold in syntax structure. Coding complexity and delay can be reduced by having the level coded in the same pass as the first transform coefficient level flag indicating whether the level is greater than the first threshold.
  • the number of valid coefficient flags for transform coefficients for the current block indicating whether the transform coefficient level of each of the transform coefficients for the current block is a non-zero valid coefficient
  • the first transform coefficient level flags By limiting the sum of the number, the number of second transform coefficient level flags, and the number of parity level flags to a predetermined threshold or less, coding complexity and delay can be reduced.
  • FIG. 8 is a flowchart illustrating an operation of a decoding apparatus according to an embodiment
  • FIG. 9 is a block diagram showing a configuration of a decoding apparatus according to an embodiment.
  • Each step disclosed in FIG. 8 may be performed by the decoding apparatus 300 disclosed in FIG. 3. More specifically, S800 and S810 may be performed by the entropy decoding unit 310 disclosed in FIG. 3, S820 may be performed by the inverse quantization unit 321 illustrated in FIG. 3, and S830 disclosed by FIG. 3 It may be performed by the inverse transform unit 322, S840 may be performed by the adder 340 disclosed in FIG. In addition, the operations according to S800 to S840 are based on some of the contents described in FIGS. 4 to 5. Therefore, detailed descriptions that overlap with those described above in FIGS. 3 to 5 will be omitted or simplified.
  • the decoding apparatus may include an entropy decoding unit 310, an inverse quantization unit 321, an inverse transformation unit 322, and an addition unit 340.
  • the decoding apparatus may be implemented by more or fewer components than those illustrated in FIG. 9.
  • the entropy decoding unit 310, the inverse quantization unit 321, the inverse conversion unit 322, and the addition unit 340 are each implemented as separate chips, or at least two or more components May be implemented through a single chip.
  • the decoding apparatus may receive a bitstream including residual information (S800). More specifically, the entropy decoding unit 310 of the decoding apparatus may receive a bitstream including residual information.
  • the decoding apparatus may derive quantized transform coefficients for the current block based on the residual information included in the bitstream (S810). More specifically, the entropy decoding unit 310 of the decoding apparatus may derive quantized transform coefficients for the current block based on the residual information included in the bitstream.
  • the decoding apparatus may derive transform coefficients for the current block from the quantized transform coefficients based on an inverse quantization process (S820). More specifically, the inverse quantization unit 321 of the decoding apparatus may derive transform coefficients for the current block from the quantized transform coefficients based on an inverse quantization process.
  • the decoding apparatus may derive residual samples for the current block by applying an inverse transform to the derived transform coefficients (S830). More specifically, the inverse transform unit 322 of the decoding apparatus may derive residual samples for the current block by applying an inverse transform to the derived transform coefficients.
  • the decoding apparatus may generate a reconstructed picture based on the residual sample for the current block (S840). More specifically, the adder 340 of the decoding apparatus may generate a reconstructed picture based on the residual sample for the current block.
  • the transform coefficients for the current block may include a first transform coefficient and a second transform coefficient coded later than the first transform coefficient.
  • the residual information includes a first transform coefficient level flag for the first transform coefficient indicating whether the transform coefficient level of the first transform coefficient is greater than a first threshold, and a transform coefficient level of the first transform coefficient is second.
  • a level flag and a second transform coefficient level flag for the second transform coefficient indicating whether the transform coefficient level of the second transform coefficient is greater than the second threshold may be included.
  • the second threshold may be greater than the first threshold.
  • the first transform to the first transform coefficient The coefficient level flag is represented by abs_level_gt1_flag[z]
  • the second transform coefficient level flag for the first transform coefficient is abs_level_gt3_flag[z]
  • the first transform coefficient level flag for the second transform coefficient is abs_level_gt1_flag[ z+1]
  • the second transform coefficient level flag for the second transform coefficient may be represented by abs_level_gt3_flag[z+1].
  • the first transform coefficient is relative to the first transform coefficient.
  • the transform coefficient level flag is represented by abs_level_gtx_flag[z][0]
  • the second transform coefficient level flag for the first transform coefficient is abs_level_gtx_flag[z][1]
  • the first for the second transform coefficient The transform coefficient level flag is represented by abs_level_gtx_flag[z+1][0]
  • the second transform coefficient level flag for the second transform coefficient can be represented by abs_level_gtx_flag[z+1][1].
  • the first threshold may be determined as 1 and the second threshold may be 2.
  • the decoding apparatus deriving the quantized transform coefficients for the current block includes: the first transform coefficient level flag for the first transform coefficient and the second transform for the first transform coefficient And parsing a coefficient level flag, the first transform coefficient level flag for the second transform coefficient, and the second transform coefficient level flag for the second transform coefficient.
  • the decoding apparatus deriving the transform coefficients for the current block includes: the first transform coefficient level flag for the first transform coefficient, and the second transform coefficient level for the first transform coefficient Deriving the transform coefficients for the current block based on a flag, the first transform coefficient level flag for the second transform coefficient, and the second transform coefficient level flag for the second transform coefficient. have.
  • the second transform coefficient level flag for the first transform coefficient may be parsed before the first transform coefficient level flag for the second transform coefficient.
  • abs_level_gtx_flag[z][1] may be parsed before abs_level_gtx_flag[z+1][0].
  • the residual information includes a parity level flag for the first transform coefficient indicating the parity of the transform coefficient level of the first transform coefficient and the transform coefficient level of the second transform coefficient.
  • a parity level flag for the second transform coefficient indicating parity may be further included.
  • the second transform coefficient level flag for the first transform coefficient may be parsed before the parity level flag for the second transform coefficient.
  • the parity level flag for the first transform coefficient is represented by par_level_flag[z]
  • the parity level flag for the second transform coefficient may be represented by par_level_flag[z+1].
  • the second transform coefficient level flag for the first transform coefficient is parsed before the first transform coefficient level flag for the second transform coefficient, and the first transform for the second transform coefficient
  • the coefficient level flag may be parsed before the parity level flag for the second transform coefficient
  • the first transform coefficient level flag for the first transform coefficient is parsed before the parity level flag for the first transform coefficient
  • the parity level flag for the first transform coefficient is the first transform coefficient.
  • the second transform coefficient level flag for the first transform coefficient is parsed before the second transform coefficient level flag for the first transform coefficient
  • the second transform coefficient level flag for the first transform coefficient is parsed before the first transform coefficient level flag for the second transform coefficient
  • the first transform coefficient level flag for the second transform coefficient is parsed before the parity level flag for the second transform coefficient
  • the parity level flag for the second transform coefficient is assigned to the second transform coefficient. May be parsed before the second transform coefficient level flag.
  • the residual information comprises: the transform for the current block including the first transform coefficient level flag for the first transform coefficient and the first transform coefficient level flag for the second transform coefficient.
  • the second transform coefficient level flags for the transform coefficients for, the transform for the current block including the parity level flag for the first transform coefficient and the parity level flag for the second transform coefficient A validity coefficient flag for the transform coefficients for the current block, including parity level flags for the coefficients, and indicating whether the transform coefficient level of each of the transform coefficients for the current block is a non-zero valid coefficient.
  • the sum of the number of first transform coefficient level flags, the number of second transform coefficient level flags, the number of parity level flags, and the number of valid coefficient flags may be less than or equal to a predetermined threshold.
  • the predetermined threshold is determined as a first threshold, and based on the determination that the size of the current block is a 2x2 block size, the predetermined The threshold may be determined as a second threshold.
  • context-based coding may be applied to the first transform coefficient level flags, the second transform coefficient level flags, the parity level flags, and the effective coefficient flags.
  • the first transform coefficient level flags, the parity level flags and the second transform coefficient level flags may be included in one for statement in syntax to form one pass. have.
  • the syntax elements When the syntax elements are included in one for statement, all three syntax elements are parsed with respect to one transform coefficient, and then the next transform coefficient is considered, thereby reducing coding complexity and reducing coding delay. have.
  • Table 12 below The syntax structure described in can be used. Table 12 below may be the same and/or similar to Table 7 above.
  • sig_coeff_flag[k] represents an example of valid coefficient flags
  • abs_level_gtx_flag[k][0] represents an example of the first transform coefficient level flags
  • par_level_flag[k] represents one of the parity level flags.
  • An example is illustrated, and abs_level_gtx_flag[k][1] represents an example of the second transform coefficient level flags.
  • the decoding apparatus receives a bitstream including residual information (S800), and is currently based on the residual information included in the bitstream.
  • Derive quantized transform coefficients for the block S810), derive transform coefficients for the current block from the quantized transform coefficients based on an inverse quantization process (S820), and inverse transform the derived transform coefficients Apply to derive residual samples for the current block (S830), and may generate a reconstructed picture based on the residual sample for the current block (S840), wherein the transform coefficients for the current block are , A first transform coefficient and a second transform coefficient coded later than the first transform coefficient, and the residual information indicates whether the transform coefficient level of the first transform coefficient is greater than a first threshold value.
  • a second transform coefficient level flag for, wherein the second threshold is greater than the first threshold, and deriving the quantized transform coefficients for the current block includes: the first transform coefficient for the first transform coefficient; A transform coefficient level flag, the second transform coefficient level flag for the first transform coefficient, the first transform coefficient level flag for the second transform coefficient, and the second transform coefficient level flag for the second transform coefficient Parsing, and deriving the transform coefficients for the current block, The first transform coefficient level flag for the first transform coefficient, the second transform coefficient level flag for the first transform coefficient, the first transform coefficient level flag for the second transform coefficient, and the second transform coefficient And deriving the
  • coding efficiency of a transform coefficient level of transform coefficients can be increased.
  • a parity level flag and a transform coefficient for a parity of a transform coefficient level include a second transform coefficient level flag indicating whether a transform coefficient level is greater than a second threshold in syntax structure. Coding complexity and delay can be reduced by having the level coded in the same pass as the first transform coefficient level flag indicating whether the level is greater than the first threshold.
  • the number of valid coefficient flags for transform coefficients for the current block indicating whether the transform coefficient level of each of the transform coefficients for the current block is a non-zero valid coefficient
  • the first transform coefficient level flags By limiting the sum of the number, the number of second transform coefficient level flags, and the number of parity level flags to a predetermined threshold or less, coding complexity and delay can be reduced.
  • the above-described method according to the present disclosure may be implemented in software form, and the encoding device and/or the decoding device according to the present disclosure may perform image processing, such as a TV, computer, smartphone, set-top box, display device, etc. Device.
  • the above-described method may be implemented as a module (process, function, etc.) performing the above-described function.
  • Modules are stored in memory and can be executed by a processor.
  • the memory may be internal or external to the processor, and may be connected to the processor by various well-known means.
  • the processor may include an application-specific integrated circuit (ASIC), other chipsets, logic circuits, and/or data processing devices.
  • the memory may include read-only memory (ROM), random access memory (RAM), flash memory, memory cards, storage media and/or other storage devices. That is, the embodiments described in the present disclosure may be implemented and implemented on a processor, microprocessor, controller, or chip.
  • the functional units shown in each figure may be implemented and implemented on a computer, processor, microprocessor, controller, or chip. In this case, information for implementation (ex. information on instructions) or an algorithm may be stored in a digital storage medium.
  • the decoding device and encoding device to which the present disclosure is applied include a multimedia broadcast transmission/reception device, a mobile communication terminal, a home cinema video device, a digital cinema video device, a surveillance camera, a video communication device, 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, 3D (3D) video devices, VR (virtual reality) devices, AR (argumente) reality) devices, video telephony video devices, transportation terminal (ex.
  • a multimedia broadcast transmission/reception device a mobile communication terminal, a home cinema video device, a digital cinema video device, a surveillance camera, a video communication device, 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, 3D (3D) video devices,
  • the 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, or a digital video recorder (DVR).
  • a game console a Blu-ray player
  • an Internet-connected TV a home theater system
  • a smartphone a tablet PC
  • DVR digital video recorder
  • the processing method to which the present disclosure is applied can be produced in the form of a computer-implemented program and stored in a computer-readable recording medium.
  • Multimedia data having a data structure according to the present disclosure can also be stored in a computer-readable recording medium.
  • the computer-readable recording medium includes all kinds of storage devices and distributed storage devices in which computer-readable data is stored.
  • the computer-readable recording medium includes, for example, Blu-ray Disc (BD), Universal Serial Bus (USB), ROM, PROM, EPROM, EEPROM, RAM, CD-ROM, magnetic tape, floppy disk and optical. It may include a data storage device.
  • the computer-readable recording medium includes media implemented in the form of a carrier wave (for example, transmission via the Internet).
  • the bitstream generated by the encoding method may be stored in a computer-readable recording medium or transmitted through a wired or wireless communication network.
  • embodiments of the present disclosure may be implemented as computer program products using program codes, and the program codes may be executed on a computer by embodiments of the present disclosure.
  • the program code can be stored on a computer readable carrier.
  • FIG. 10 shows an example of a content streaming system to which the invention disclosed in this document can be applied.
  • a content streaming system to which the present disclosure is applied may largely include an encoding server, a streaming server, a web server, a media storage, a user device, and a multimedia input device.
  • the encoding server serves to compress a content input from multimedia input devices such as a smart phone, a camera, and a camcorder into digital data to generate a bitstream and transmit it to the streaming server.
  • multimedia input devices such as a smart phone, a camera, and a camcorder directly generate a bitstream
  • the encoding server may be omitted.
  • the bitstream may be generated by an encoding method or a bitstream generation method to which the present disclosure is applied, and the streaming server may temporarily store the bitstream in the process of transmitting or receiving the bitstream.
  • the streaming server transmits multimedia data to a user device based on a user request through a web server, and the web server serves as an intermediary to inform the user of the service.
  • the web server delivers it to the streaming server, and the streaming server transmits multimedia data to the user.
  • the content streaming system may include a separate control server, in which case the control server serves to control commands/responses 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 terminal for digital broadcasting, a personal digital assistants (PDA), a portable multimedia player (PMP), navigation, a slate PC, Tablet PC, ultrabook, wearable device (e.g., smartwatch, smart glass, head mounted display (HMD)), digital TV, desktop Computers, digital signage, and the like.
  • PDA personal digital assistants
  • PMP portable multimedia player
  • slate PC slate PC
  • Tablet PC tablet
  • ultrabook ultrabook
  • wearable device e.g., smartwatch, smart glass, head mounted display (HMD)
  • digital TV desktop Computers, digital signage, and the like.
  • Each server in the content streaming system can be operated as a distributed server, and in this case, data received from each server can be distributed.

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Abstract

La présente invention concerne un procédé de décodage d'image, qui est exécuté par un dispositif de décodage, ledit procédé de décodage d'image étant caractérisé en ce qu'il comprend: une étape consistant à recevoir un train de bits comportant des informations résiduelles; une étape consistant à dériver des coefficients de transformée quantifiés pour un bloc actuel sur la base des informations résiduelles incluses dans le train de bits; une étape consistant à dériver des coefficients de transformée à partir des coefficients de transformée quantifiés sur la base d'un procédé de déquantification inverse; une étape consistant à dériver des échantillons résiduels pour le bloc actuel par application d'une transformée inverse aux coefficients de transformée dérivés; et une étape consistant à générer une image reconstruite sur la base de l'échantillon résiduel pour le bloc actuel.
PCT/KR2019/018177 2018-12-20 2019-12-20 Procédé et appareil pour coder des niveaux de coefficients de transformée de coefficients de transformée WO2020130705A1 (fr)

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