WO2023068840A1 - 비분리 1차 변환 설계 방법 및 장치 - Google Patents
비분리 1차 변환 설계 방법 및 장치 Download PDFInfo
- Publication number
- WO2023068840A1 WO2023068840A1 PCT/KR2022/016033 KR2022016033W WO2023068840A1 WO 2023068840 A1 WO2023068840 A1 WO 2023068840A1 KR 2022016033 W KR2022016033 W KR 2022016033W WO 2023068840 A1 WO2023068840 A1 WO 2023068840A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- transform
- separate
- kernels
- transformation
- kernel
- Prior art date
Links
- 238000000034 method Methods 0.000 title claims description 158
- 230000009466 transformation Effects 0.000 claims description 207
- 238000006243 chemical reaction Methods 0.000 claims description 43
- 238000000926 separation method Methods 0.000 claims description 30
- 230000005540 biological transmission Effects 0.000 claims description 14
- 238000012545 processing Methods 0.000 abstract description 20
- 230000011664 signaling Effects 0.000 abstract description 12
- 230000000694 effects Effects 0.000 abstract description 3
- 239000011159 matrix material Substances 0.000 description 84
- 230000008569 process Effects 0.000 description 45
- 239000013598 vector Substances 0.000 description 43
- 238000001914 filtration Methods 0.000 description 31
- 238000013139 quantization Methods 0.000 description 30
- 208000037170 Delayed Emergence from Anesthesia Diseases 0.000 description 25
- 239000000523 sample Substances 0.000 description 25
- 230000006870 function Effects 0.000 description 24
- 230000003044 adaptive effect Effects 0.000 description 12
- 230000002123 temporal effect Effects 0.000 description 7
- 230000001131 transforming effect Effects 0.000 description 7
- 238000004364 calculation method Methods 0.000 description 6
- 238000010586 diagram Methods 0.000 description 6
- 230000001965 increasing effect Effects 0.000 description 6
- 238000013507 mapping Methods 0.000 description 6
- 241000023320 Luma <angiosperm> Species 0.000 description 5
- 238000004891 communication Methods 0.000 description 5
- 230000006835 compression Effects 0.000 description 5
- 238000007906 compression Methods 0.000 description 5
- 230000001419 dependent effect Effects 0.000 description 5
- 230000014509 gene expression Effects 0.000 description 5
- OSWPMRLSEDHDFF-UHFFFAOYSA-N methyl salicylate Chemical compound COC(=O)C1=CC=CC=C1O OSWPMRLSEDHDFF-UHFFFAOYSA-N 0.000 description 5
- 238000000844 transformation Methods 0.000 description 5
- 230000006978 adaptation Effects 0.000 description 4
- 238000000638 solvent extraction Methods 0.000 description 4
- 230000009467 reduction Effects 0.000 description 3
- 241000209094 Oryza Species 0.000 description 2
- 235000007164 Oryza sativa Nutrition 0.000 description 2
- 230000002146 bilateral effect Effects 0.000 description 2
- 230000000295 complement effect Effects 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 239000013074 reference sample Substances 0.000 description 2
- 235000009566 rice Nutrition 0.000 description 2
- 238000012546 transfer Methods 0.000 description 2
- 238000011426 transformation method Methods 0.000 description 2
- 241000385654 Gymnothorax tile Species 0.000 description 1
- 238000004422 calculation algorithm Methods 0.000 description 1
- 238000004590 computer program Methods 0.000 description 1
- 238000013500 data storage Methods 0.000 description 1
- 101150089388 dct-5 gene Proteins 0.000 description 1
- 230000009977 dual effect Effects 0.000 description 1
- 238000003709 image segmentation Methods 0.000 description 1
- 230000001939 inductive effect Effects 0.000 description 1
- 238000010295 mobile communication Methods 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 238000003672 processing method Methods 0.000 description 1
- 230000008707 rearrangement Effects 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 239000010454 slate Substances 0.000 description 1
- 239000004984 smart glass Substances 0.000 description 1
- 230000000153 supplemental effect Effects 0.000 description 1
- 230000002194 synthesizing effect Effects 0.000 description 1
Images
Classifications
-
- 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
- H04N19/13—Adaptive entropy coding, e.g. adaptive variable length coding [AVLC] or context adaptive binary arithmetic coding [CABAC]
-
- 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
- H04N19/17—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding the unit being an image region, e.g. an object
- H04N19/176—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding the unit being an image region, e.g. an object the region being a block, e.g. a macroblock
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
- H04N19/10—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
-
- 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
- This document relates to video/image coding technology, and more particularly, to a method for effectively signaling transform-related information when performing non-separate primary transform in a video or video coding system.
- VR Virtual Reality
- AR Artificial Reality
- broadcasting is on the rise.
- a highly efficient video/image compression technology is required to effectively compress, transmit, store, and reproduce high-resolution and high-quality video/image information having various characteristics as described above.
- a method and apparatus for increasing video/image coding efficiency are provided.
- an image coding method and apparatus related to a first transform from a spatial domain to a frequency domain including a non-separate transform are provided.
- a method and apparatus for effectively signaling transform index information based on primary transform including separative transform and non-separate transform are provided.
- a method and apparatus for efficiently applying a primary transform and a secondary transform are provided.
- a method and apparatus for efficiently transmitting kernel-related information applied to a primary transform including a non-separate transform are provided.
- a video/image decoding method performed by a decoding device is provided.
- a decoding device for performing video/image decoding is provided.
- a video/video encoding method performed by an encoding device is provided.
- an encoding device for performing video/video encoding is provided.
- a computer-readable digital storage medium in which encoded video/image information generated according to the video/image encoding method disclosed in at least one of the embodiments of this document is stored is provided.
- encoded information or encoded video/image information causing a decoding device to perform a video/image decoding method disclosed in at least one of the embodiments of this document is stored in a computer readable digital Provide a storage medium.
- a method of transmitting video/image data including a bitstream generated based on the video/image encoding method disclosed in at least one of the embodiments of this document is provided.
- a transmission device for transmitting video/image data including a bitstream generated based on the video/image encoding method disclosed in at least one of the embodiments of this document is provided.
- FIG. 1 schematically shows an example of a video/image coding system to which embodiments of this document can be applied.
- FIG. 2 is a diagram schematically illustrating a configuration of a video/image encoding apparatus to which embodiments of the present document may be applied.
- FIG. 3 is a diagram schematically illustrating a configuration of a video/image decoding device to which embodiments of the present document may be applied.
- 5 illustratively shows intra-directional modes of 65 prediction directions.
- FIG. 7 is a diagram for explaining RST according to an embodiment of the present document.
- CABAC context-adaptive binary arithmetic coding
- FIGS. 9 and 10 schematically illustrate an example of a video/image encoding method and related components according to the embodiment(s) of this document.
- FIG. 11 and 12 schematically illustrate an example of a video/image decoding method and related components according to an embodiment of the present document.
- FIG. 13 shows an example of a content streaming system to which the embodiments disclosed in this document can be applied.
- each component in the drawings described in this document is shown independently for convenience of description of different characteristic functions, and does not mean that each component is implemented as separate hardware or separate software.
- two or more of the components 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 rights of this document as long as they do not deviate from the essence of this document.
- FIG. 1 schematically shows an example of a video/image coding system to which embodiments of this document can be applied.
- a video/image coding system may include a first device (source device) and a second device (receive device).
- the source device may transmit encoded video/image information or data to a receiving device in a file or streaming form through a digital storage medium or network.
- 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 device, and a renderer.
- the encoding device may be referred to as a video/image encoding device, and the decoding device may be referred to as a video/image decoding device.
- a transmitter may be included in an encoding device.
- a receiver may be included in a decoding device.
- the renderer may include a display unit, and the display unit may be configured as a separate device or an external component.
- a video source may acquire video/images through a process of capturing, synthesizing, or generating video/images.
- a video source may include a video/image capture device and/or a video/image generation device.
- a video/image capture device may include, for example, one or more cameras, a video/image archive containing previously captured video/images, and the like.
- Video/image generating devices may include, for example, computers, tablets and smart phones, etc., and may (electronically) generate video/images.
- 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.
- An encoding device may encode an input video/image.
- the encoding device may perform a series of procedures such as prediction, transformation, and quantization for compression and coding efficiency.
- Encoded data (encoded video/video information) may be output in the form of a bitstream.
- the transmission unit may transmit the encoded video/image information or data output in the form of a bit stream to the receiving unit of the receiving device in the form of a file or streaming through a digital storage medium or a network.
- Digital storage media may include various storage media such as USB, SD, CD, DVD, Blu-ray, HDD, and 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 broadcasting/communication network.
- the receiving unit may receive/extract the bitstream and transmit it to a decoding device.
- the decoding device may decode video/images by performing a series of procedures such as inverse quantization, inverse transformation, and prediction corresponding to operations of the encoding device.
- the renderer may render the decoded video/image.
- the rendered video/image may be displayed through the display unit.
- This document is about video/image coding.
- the method/embodiment disclosed in this document may be applied to a method disclosed in a versatile video coding (VVC) standard.
- the method/embodiment disclosed in this document is an essential video coding (EVC) standard, an AOMedia Video 1 (AV1) standard, a 2nd generation of audio video coding standard (AVS2), or a next-generation video/image coding standard (ex. H.267 or H.268, etc.).
- EVC essential video coding
- AV1 AOMedia Video 1
- AVS2 2nd generation of audio video coding standard
- next-generation video/image coding standard ex. H.267 or H.268, etc.
- a video may mean a set of a series of images over time.
- a picture generally means a unit representing one image in a specific time period
- a slice/tile is a unit constituting a part of a picture in coding.
- a slice/tile may include one or more coding tree units (CTUs).
- CTUs coding tree units
- One picture may consist of one or more slices/tiles.
- a tile is a rectangular region of CTUs within a particular tile column and a particular tile row in a picture.
- the tile column is a rectangular region of CTUs having the same height as the picture, and a width specified by syntax elements in a picture parameter set (The tile column is a rectangular region of CTUs having).
- the tile row is a rectangular region of CTUs, the rectangular region has a height specified by syntax elements in a picture parameter set, and a width equal to the width 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 may represent a specific sequential ordering of CTUs partitioning a picture, the CTUs may be ordered sequentially with a CTU raster scan within a tile, and tiles within a picture may be sequentially ordered 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 contain an integer number of complete tiles or an integer number of consecutive complete CTU rows within a tile of a picture, which may be contained exclusively in a single NAL unit. complete CTU rows within a tile of a picture that may be exclusively contained in a single NAL unit)
- one picture may be divided into two or more sub-pictures.
- a subpicture may be a rectangular region of one or more slices within a picture.
- a pixel or pel may mean a minimum unit constituting one picture (or image). Also, 'sample' may be used as a term corresponding to a pixel.
- a sample may generally represent a pixel or a pixel value, may represent only a pixel/pixel value of a luma component, or only a pixel/pixel value of a chroma component.
- a unit may represent a basic unit of image processing.
- a unit may include at least one of a specific region of a picture and information related to the region.
- One unit may include one luma block and two chroma (eg cb, cr) blocks. Unit may be used interchangeably with terms such as block or area depending on the case.
- an MxN block may include samples (or a sample array) or a set (or array) of transform coefficients consisting of M columns and N rows.
- a or B may mean “only A”, “only B” or “both A and B”.
- a or B in this document may be interpreted as “A and/or B”.
- A, B or C in this document means “only A”, “only B”, “only C”, or “any and all combinations of A, B and C ( any combination of A, B and C)”.
- a slash (/) or comma (comma) used in this document may mean “and/or”.
- A/B can mean “A and/or B”. Accordingly, “A/B” may mean “only A”, “only B”, or “both A and B”.
- A, B, C may mean “A, B or C”.
- At least one of A and B may mean “only A”, “only B”, or “both A and B”.
- the expression “at least one of A or B” or “at least one of A and/or B” means “at least one It can be interpreted the same as "A and B (at least one of A and B) of
- At least one of A, B and C means “only A”, “only B”, “only C”, or “A, B and C” It may mean “any combination of A, B and C”. Also, “at least one of A, B or C” or “at least one of A, B and/or C” means It can mean “at least one of A, B and C”.
- parentheses used in this document may mean “for example”. Specifically, when it is indicated as “prediction (intra prediction)”, “intra prediction” may be suggested as an example of “prediction”. In other words, “prediction” in this document is not limited to “intra prediction”, and “intra prediction” may be suggested as an example of “prediction”. Also, even when indicated as “prediction (ie, intra prediction)”, “intra prediction” may be suggested as an example of “prediction”.
- an encoding device may include a video encoding device and/or a video encoding device.
- the encoding device 200 includes an image partitioner 210, a predictor 220, a residual processor 230, an entropy encoder 240, It may include an adder 250, a filter 260, and a 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 called a reconstructor or a reconstructed block generator.
- the above-described image segmentation unit 210, prediction unit 220, residual processing unit 230, entropy encoding unit 240, adder 250, and filtering unit 260 may be 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) and 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 divider 210 may divide an input image (or picture or frame) input to the encoding device 200 into one or more processing units.
- the processing unit may be called a coding unit (CU).
- the coding unit may be partitioned recursively from a coding tree unit (CTU) or a largest coding unit (LCU) according to a quad-tree binary-tree ternary-tree (QTBTTT) structure.
- CTU coding tree unit
- LCU largest coding unit
- QTBTTT quad-tree binary-tree ternary-tree
- one coding unit may be divided into a plurality of coding units of 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 ternary structure may be applied later.
- a binary tree structure may be applied first.
- a coding procedure according to this document may be performed based on a final coding unit that is not further divided. In this case, based on the coding efficiency according to the image characteristics, the largest coding unit can be directly used as the final coding unit, or the coding unit is recursively divided into coding units of lower depth as needed to obtain an optimal A coding unit having a size of may 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 divided or partitioned from the above-described final coding unit.
- the prediction unit may be a unit of sample prediction
- the transform unit may be a unit for deriving transform coefficients and/or a unit for deriving a residual signal from transform coefficients.
- an MxN block may represent a set of samples or transform coefficients consisting of M columns and N rows.
- a sample may generally represent a pixel or a pixel value, may represent only a pixel/pixel value of a luma component, or only a pixel/pixel value of a chroma component.
- a sample may be used as a term corresponding to one picture (or image) to a pixel or a pel.
- the encoding device 200 subtracts the prediction signal (predicted block, prediction sample array) output from the inter prediction unit 221 or the intra prediction unit 222 from the input video signal (original block, original sample array) to obtain a residual A signal (residual signal, residual block, residual sample array) may be generated, and the generated residual signal is transmitted to the conversion unit 232 .
- a unit for subtracting a prediction signal (prediction block, prediction sample array) from an input video signal (original block, original sample array) in the encoder 200 may be called 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 or inter prediction is applied in units of current blocks or CUs. As will be described later in the description of each prediction mode, the prediction unit may generate and transmit various information related to prediction, such as prediction mode information, to the entropy encoding unit 240 . Prediction-related information may be encoded in the entropy encoding unit 240 and output in the form of a bitstream.
- the intra predictor 222 may predict a current block by referring to samples in the current picture.
- the referenced samples may be located in the neighborhood of the current block or may be located apart from each other according to 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.
- the directional modes 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 according to settings.
- the intra predictor 222 may determine a prediction mode applied to the current block by using a prediction mode applied to neighboring blocks.
- the inter-prediction unit 221 may derive a predicted block for a current block based on a reference block (reference sample array) specified by a motion vector on a reference picture.
- motion information may be predicted in units of blocks, subblocks, or samples based on correlation of motion information between neighboring blocks and the current block.
- the motion information may include a motion vector and a reference picture index.
- the motion information may further include inter prediction direction (L0 prediction, L1 prediction, Bi prediction, etc.) information.
- a neighboring block may include a spatial neighboring block present in the current picture and a temporal neighboring block present in the reference picture.
- a reference picture including the reference block and a reference picture including the temporal neighboring block may be the same or different.
- the temporal neighboring block may be called a collocated reference block, a collocated CU (colCU), and the like, 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 candidate is used to derive the motion vector and/or reference picture index of the current block. can create Inter prediction may be performed based on various prediction modes. For example, in the case of skip mode and 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 unlike the merge mode.
- MVP motion vector prediction
- the prediction unit 220 may generate a prediction signal based on various prediction methods described below.
- the predictor may apply intra-prediction or inter-prediction to predict one block, as well as apply intra-prediction and inter-prediction at the same time. This may 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 block prediction.
- IBC intra block copy
- the IBC prediction mode or the palette mode may be used for video/video coding of content such as a game, for example, screen content coding (SCC).
- SCC screen content coding
- IBC basically performs prediction within the current picture, but may be performed similarly to inter prediction in that a reference block is derived within the current picture. That is, IBC may use at least one of the inter prediction techniques described in this document.
- Palette mode can be viewed as an example of intra coding or intra prediction. When the palette mode is applied, a sample value within a picture may be signaled based on information
- a prediction signal generated through the prediction unit may be used to generate a restored signal or a residual signal.
- the transform unit 232 may generate transform coefficients by applying a transform technique to the residual signal.
- the transformation technique may include at least one of Discrete Cosine Transform (DCT), Discrete Sine Transform (DST), Graph-Based Transform (GBT), and Conditionally Non-linear Transform (CNT).
- DCT Discrete Cosine Transform
- DST Discrete Sine Transform
- GBT Graph-Based Transform
- CNT Conditionally Non-linear Transform
- GBT means a conversion obtained from the graph when relation information between pixels is expressed as a graph.
- CNT means a transformation obtained based on generating a prediction signal using all previously reconstructed pixels.
- the conversion process may be applied to square pixel blocks having the same size, or may be applied to non-square blocks of variable size.
- the quantization unit 233 quantizes the transform coefficients and transmits them to the entropy encoding unit 240, and the entropy encoding unit 240 may encode the quantized signal (information on the quantized transform coefficients) and output it as a bitstream. there is. 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 the quantized transform coefficients based on the one-dimensional vector form quantized transform coefficients. Information about transform coefficients may be generated.
- the entropy encoding unit 240 may perform various encoding methods such as exponential Golomb, context-adaptive variable length coding (CAVLC), and context-adaptive binary arithmetic coding (CABAC).
- the entropy encoding unit 240 may encode together or separately information necessary for video/image reconstruction (eg, values of syntax elements) in addition to quantized transform coefficients.
- Encoded information eg, encoded video/video information
- NAL network abstraction layer
- the video/video information may further include information on various parameter sets such as an adaptation parameter set (APS), a picture parameter set (PPS), a sequence parameter set (SPS), or a video parameter set (VPS).
- the video/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/image information.
- the video/image information may be encoded through the above-described encoding procedure and included in the bitstream.
- the bitstream may be transmitted through a network or stored in a digital storage medium.
- the network may include a broadcasting network and/or a communication network
- the digital storage medium may include various storage media such as USB, SD, CD, DVD, Blu-ray, HDD, and SSD.
- a transmission unit (not shown) for transmitting the signal output from the entropy encoding unit 240 and/or a storage unit (not shown) for storing may be configured as internal/external elements of the encoding device 200, or the transmission unit It may also 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 250 adds the reconstructed residual signal to the prediction signal output from the inter predictor 221 or the intra predictor 222 to obtain a reconstructed signal (reconstructed picture, reconstructed block, reconstructed sample array) can be created
- a predicted block may be used as a reconstruction block.
- the adder 250 may be called a restoration unit or a restoration block generation unit.
- the generated reconstruction signal may be used for intra prediction of the next processing target block in the current picture, or may be used for inter prediction of the next picture after filtering as described below.
- LMCS luma mapping with chroma scaling
- the filtering unit 260 may improve subjective/objective picture quality by applying filtering to the reconstructed signal.
- the filtering unit 260 may generate a modified reconstructed picture by applying various filtering methods to the reconstructed picture, and store the modified reconstructed picture in the memory 270, specifically the DPB of 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 filtering-related information and transmit them to the entropy encoding unit 240, as will be described later in the description of each filtering method. Filtering-related information may be encoded in 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 .
- the encoding device can avoid prediction mismatch between the encoding device 200 and the decoding device, and can also improve encoding efficiency.
- the DPB of the memory 270 may store the modified reconstructed picture to be used as a reference picture in the inter prediction unit 221 .
- the memory 270 may store motion information of a block in a current picture from which motion information is derived (or encoded) and/or motion information of blocks in a previously reconstructed picture.
- 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 reconstructed blocks in the current picture and transfer them to the intra predictor 222 .
- a decoding device may include an image decoding device and/or a video decoding device.
- the decoding device 300 includes an entropy decoder 310, a residual processor 320, a 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 dequantizer 321 and an inverse transformer 321 .
- the above-described entropy decoding unit 310, residual processing unit 320, prediction unit 330, adder 340, and filtering unit 350 may be configured as one hardware component (for example, a decoder chipset or processor) according to an embodiment. ) can be configured by Also, the memory 360 may include a decoded picture buffer (DPB) and may be configured by a digital storage medium.
- the hardware component may further include a memory 360 as an internal/external component.
- the decoding device 300 may restore an image corresponding to a process in which the video/image information is processed by the encoding device of FIG. 2 .
- the decoding device 300 may derive units/blocks based on block division related information obtained from the bitstream.
- the decoding device 300 may perform decoding using a processing unit applied in the encoding device.
- a processing unit of decoding may be a coding unit, for example, and a coding unit may be partitioned from a coding tree unit or a largest coding unit along a quad tree structure, a binary tree structure and/or a ternary tree structure.
- One or more transform units may be derived from a coding unit.
- the restored video signal decoded and output through the decoding device 300 may be reproduced through a playback device.
- the decoding device 300 may receive a signal output from the encoding device 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 restoration (or picture restoration).
- the video/video information may further include information on various parameter sets such as an adaptation parameter set (APS), a picture parameter set (PPS), a sequence parameter set (SPS), or a video parameter set (VPS).
- the video/image information may further include general constraint information.
- the decoding device may decode a picture further based on the information about the parameter set and/or the general restriction information.
- Signaled/received information and/or syntax elements described later in this document may be obtained from the bitstream by being decoded through the decoding procedure.
- the entropy decoding unit 310 decodes information in a bitstream based on a coding method such as exponential Golomb coding, CAVLC, or CABAC, and values of syntax elements required for image reconstruction and quantized values of transform coefficients related to residuals. can output them.
- the CABAC entropy decoding method receives bins corresponding to each syntax element in a bitstream, and converts syntax element information to be decoded and decoding information of neighboring and decoding object blocks or symbol/bin information decoded in a previous step.
- a symbol corresponding to the value of each syntax element can be generated by determining a context model, predicting the probability of occurrence of a bin according to the determined context model, and performing arithmetic decoding of the bin.
- the CABAC entropy decoding method may update the context model by using information of the decoded symbol/bin for the context model of the next symbol/bin after determining the context model.
- prediction-related information is provided to the prediction unit (inter prediction unit 332 and intra prediction unit 331), and entropy decoding is performed by the entropy decoding unit 310.
- Dual values that is, quantized transform coefficients and related parameter information may be input to the residual processing unit 320 .
- the residual processor 320 may derive a residual signal (residual block, residual samples, residual sample array). Also, among information decoded by the entropy decoding unit 310 , information about filtering 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 referred to as a video/video/picture decoding device, and the decoding device may be divided into an information decoder (video/video/picture information decoder) and a sample decoder (video/video/picture sample decoder).
- the information decoder may include the entropy decoding unit 310, and the sample decoder includes the inverse quantization unit 321, an inverse transform unit 322, an adder 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 inversely quantize the quantized transform coefficients and output transform coefficients.
- the inverse quantization unit 321 may rearrange the quantized transform coefficients in a 2D block form. In this case, the rearrangement may be performed based on a coefficient scanning order performed by the encoding device.
- the inverse quantization unit 321 may perform inverse quantization on quantized transform coefficients using a quantization parameter (eg, quantization step size information) and obtain transform coefficients.
- a quantization parameter eg, quantization step size information
- a residual signal (residual block, residual sample array) is obtained by inverse transforming the transform coefficients.
- the prediction unit 330 may perform prediction on a current block and generate a predicted block including predicted samples of the current block.
- the prediction unit 330 may determine whether intra prediction or inter prediction is applied to the current block based on the information about the prediction output from the entropy decoding unit 310, and determine a specific intra/inter prediction mode.
- the prediction unit 330 may generate a prediction signal based on various prediction methods described later. For example, the prediction unit 330 may apply intra-prediction or inter-prediction to predict one block, and may simultaneously apply intra-prediction and inter-prediction. This may be called combined inter and intra prediction (CIIP). Also, the prediction unit 330 may be based on an intra block copy (IBC) prediction mode or a palette mode for block prediction.
- IBC intra block copy
- the IBC prediction mode or the palette mode may be used for video/video coding of content such as a game, for example, screen content coding (SCC). IBC basically performs prediction within the current picture, but may be performed similarly to inter prediction in that a reference block is derived within the current picture. That is, IBC may use at least one of the inter prediction techniques described in this document.
- Palette mode can be viewed as an example of intra coding or intra prediction. When the palette mode is applied, information on a palette table and a palette index may be included in the video/image information and signaled.
- the intra predictor 331 may predict a current block by referring to samples in the current picture.
- the referenced samples may be located in the neighborhood of the current block or may be located apart from each other according to 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 by using a prediction mode applied to neighboring blocks.
- the inter prediction unit 332 may derive a predicted block for a current block based on a reference block (reference sample array) specified by a motion vector on a reference picture.
- motion information may be predicted in units of blocks, subblocks, or samples based on correlation of motion information between neighboring blocks and the current block.
- the motion information may include a motion vector and a reference picture index.
- the motion information may further include inter prediction direction (L0 prediction, L1 prediction, Bi prediction, etc.) information.
- a 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 predictor 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 the prediction information may include information indicating an inter prediction mode for the current block.
- the adder 340 restores 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). Signals (reconstructed picture, reconstructed block, reconstructed sample array) can be generated. When there is no residual for the block to be processed, such as when the skip mode is applied, a predicted block may be used as a reconstruction block.
- the adder 340 may be called a restoration unit or a restoration block generation unit.
- the generated reconstruction signal may be used for intra prediction of the next processing target block in the current picture, output after filtering as described later, or may be used for inter prediction of the next picture.
- LMCS luma mapping with chroma scaling
- the filtering unit 350 may improve subjective/objective picture 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 store the modified reconstructed picture in the memory 360, specifically the DPB of the memory 360.
- the various filtering methods may include, for example, deblocking filtering, sample adaptive offset, adaptive loop filter, bilateral filter, and the like.
- a (modified) 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 in the current picture from which motion information is derived (or decoded) and/or motion information of blocks in a previously reconstructed picture.
- the stored motion information may be transmitted to the inter prediction unit 332 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 reconstructed blocks in the current picture and transfer them 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 200 are the filtering unit 350 and the inter prediction of the decoding device 300, respectively.
- the same or corresponding may be applied to the unit 332 and the intra predictor 331.
- the predicted block includes prediction samples in the spatial domain (or pixel domain).
- the predicted block is identically derived from an encoding device and a decoding device, and the encoding device decodes residual information (residual information) between the original block and the predicted block, rather than the original sample value itself of the original block.
- Video coding efficiency can be increased by signaling to the device.
- the decoding device may derive a residual block including residual samples based on the residual information, generate a reconstructed block including reconstructed samples by combining the residual block and the predicted block, and reconstruct the reconstructed blocks. It is possible to create a reconstruction picture that contains
- the residual information may be generated through transformation and quantization procedures.
- the encoding apparatus derives a residual block between the original block and the predicted block, and derives transform coefficients by performing a transform procedure on residual samples (residual sample array) included in the residual block. And, by performing a quantization procedure on the transform coefficients, quantized transform coefficients may be derived, and related residual information may be signaled to the decoding device (through a bitstream).
- the residual information may include information such as value information of the quantized transform coefficients, location information, transform technique, transform kernel, and quantization parameter.
- the decoding device may perform an inverse quantization/inverse transform procedure based on the residual information and derive residual samples (or residual blocks).
- the decoding device may generate a reconstructed picture based on the predicted block and the residual block.
- the encoding device may also derive a residual block by inverse quantizing/inverse transforming the quantized transform coefficients for reference for inter prediction of a later picture, and generate a reconstructed picture based on the residual block.
- At least one of quantization/inverse quantization and/or transform/inverse transform may be omitted. If the quantization/inverse quantization is omitted, the quantized transform coefficient may be referred to as a transform coefficient. If the transform/inverse transform is omitted, the transform coefficients may be called coefficients or residual coefficients, or may still be called transform coefficients for unity of expression. Whether to omit the transform/inverse transform may be signaled based on a transform skip flag. For example, the transform skip flag may be a transform_skip_flag syntax element.
- quantized transform coefficients and transform coefficients may be referred to as transform coefficients and scaled transform coefficients, respectively.
- the residual information may include information on transform coefficient(s), and the information on the transform coefficient(s) may be signaled through residual coding syntax.
- Transform coefficients may be derived based on the residual information (or information about the transform coefficient(s)), and scaled transform coefficients may be derived through inverse transform (scaling) of the transform coefficients.
- Residual samples may be derived based on an inverse transform (transform) of the scaled transform coefficients. This may be applied/expressed in other parts of this document as well.
- the coded video/image includes a video coding layer (VCL) that handles video/image decoding and itself, a subsystem that transmits and stores coded information, and a VCL and subsystem. It can be divided into NAL (network abstraction layer), which exists in between and is in charge of network adaptation function.
- VCL video coding layer
- NAL network abstraction layer
- VCL data including compressed image data is generated, or a Picture Parameter Set (PPS), a Sequence Parameter Set (SPS), a video parameter set ( A parameter set including a video parameter set (VPS) or a Supplemental Enhancement Information (SEI) message additionally required for an image decoding process may be generated.
- PPS Picture Parameter Set
- SPS Sequence Parameter Set
- VCL video parameter set
- SEI Supplemental Enhancement Information
- a NAL unit may be generated by adding header information (NAL unit header) to a Raw Byte Sequence Payload (RBSP) generated in VCL.
- the RBSP may refer to slice data, parameter set, SEI message, and the like generated in the VCL.
- the NAL unit header may include NAL unit type information designated according to RBSP data included in the corresponding NAL unit.
- NAL units may be classified into VCL NAL units and non-VCL NAL units according to RBSPs generated in VCL.
- a VCL NAL unit may refer to a NAL unit including information about an image (slice data)
- a non-VCL NAL unit refers to a NAL unit including information (parameter set or SEI message) required for image decoding. can mean .
- VCL NAL unit and non-VCL NAL unit may be transmitted over a network by attaching header information according to a data standard of a subsystem.
- the NAL unit is a data format of a predetermined standard such as H.266 / VVC file format, real-time transport protocol (RTP), transport stream (TS), etc. data format) and can be transmitted through various networks.
- the NAL unit type may be designated according to the RBSP data structure included in the NAL unit, and information on the NAL unit type may be stored in the NAL unit header and signaled.
- a NAL unit may be classified into a VCL NAL unit type and a non-VCL NAL unit type according to whether or not it includes information about an image (slice data).
- VCL NAL unit types may be classified according to the nature and type of pictures included in the VCL NAL units, and non-VCL NAL unit types may be classified according to parameter set types.
- NAL unit types designated according to the type of parameter set included in the non-VCL NAL unit type.
- NAL unit type for NAL unit including DCI
- NAL unit Type for NAL unit including VPS
- NAL unit type for NAL unit including SPS
- NAL unit type for NAL unit including PPS
- NAL unit type for NAL unit including APS
- NAL unit type for NAL unit including PH
- the above-described NAL unit types may have syntax information for the NAL unit type, and the syntax information may be stored and signaled in a NAL unit header.
- the syntax information may be nal_unit_type, and the NAL unit type may be designated as a nal_unit_type value.
- one picture may include a plurality of slices, and each slice may include a slice header and slice data.
- one picture header may be added (embedded) for a plurality of slices (set of slice header and slice data).
- a picture header may include information/parameters commonly applicable to pictures.
- a slice header may include information/parameters commonly applicable to slices.
- APS APS syntax
- PPS PPS syntax
- SPS SPS syntax
- VPS syntax may include information/parameters commonly applicable to a plurality of layers.
- DPS may include information/parameters commonly applicable to all images.
- DCI may include information/parameters that can be commonly applied to overall video.
- DCI may include information/parameters related to decoding capability.
- High Level Syntax may include, for example, at least one of APS syntax, PPS syntax, SPS syntax, VPS syntax, DCI syntax, picture header syntax, and slice header syntax.
- the low level syntax is, for example, slice data (slice data) syntax, CTU (coding tree unit) syntax, CU (coding unit) syntax, TU (transform unit) syntax among may contain at least one.
- video/video information encoded from an encoding device to a decoding device and signaled in the form of a bitstream may include intra-picture partitioning related information, intra/inter prediction information, residual information, and in-loop filtering information.
- the image/video information may include slice header information, picture header information, APS information, PPS information, SPS information, VPS information, and/or DCI information.
- the image/video information may further include general constraint information and/or NAL unit header information.
- information and/or syntax elements transmitted/signaled from the encoding device to the decoding device are encoded through the above-described encoding procedure and included in the bitstream, and the information and/or syntax elements signaled/received are encoded as described above. It can be decoded through a decoding procedure and obtained from the bitstream.
- the decoding device performs parsing, which is an operation of reading bits for each information and/or syntax element from the bitstream in order to decode the signaled/received information and/or syntax elements. can do.
- each of the following coding descriptors may indicate a parsing process for a specific syntax element.
- -ae(v) A function that decodes a syntax element encoded with context-adaptive arithmetic entropy-coded syntax element (CABAC).
- CABAC context-adaptive arithmetic entropy-coded syntax element
- -b(8) A function that reads a byte (8 bits) having an arbitrary bit pattern.
- the parsing process for this descriptor can be specified by the return value of the read_bits(8) function. (byte having any pattern of bit string (8bits).
- the parsing process for this descriptor is specified by the return value of the function read_bits(8)).
- -i(n) A function that decodes a syntax element coded as a signed integer using n bits. If n is "v" in the syntax table, the number of bits may vary depending on the values of other syntax elements.
- the parsing process for this descriptor can be specified by the return value of the read_bits(n) function where the first most significant bit (MSB) written is interpreted as a two's complement integer representation. (signed integer using n bits. When n is "v” in the syntax table, the number of bits varies in a manner dependent on the value of other syntax elements.
- the parsing process for this descriptor is specified by the return value of the function read_bits(n) interpreted as a two's complement integer representation with the most significant bit written first).
- -se(v) a function that decodes a syntax element encoded with signed 0th order Exp-Golomb
- the parsing process for this descriptor can be specified with order k equal to 0. (signed integer 0-th order Exp-Golomb-coded syntax element with the left bit first.
- the parsing process for this descriptor is specified with the order k equal to 0).
- -st(v) A null-terminated bitstream encoded in UCS Transmission Format-8 (UTF-8) characters, as specified in ISO/IEC 10646, the parsing process for this descriptor may be specified as can For example, st(v) reads and returns a sequence of bytes from the bitstream, starting at the current position, up to the next byte-aligned byte, such as 0x00, and advancing the bitstream pointer by (stringLength + 1) * 8 bit positions. can make it Here, stringLength may be equal to the number of bytes returned. Also, here, the st(v) descriptor can be used only when the current position of the bitstream is a byte alignment position.
- st(v) begins at a byte-aligned position in the bitstream and reads and returns a series of bytes from the bitstream, beginning at the current position and continuing up to but not including the next byte-aligned byte that is equal to 0x00, and advances the bitstream pointer by ( stringLength + 1 ) * 8 bit positions, where stringLength is equal to the number of bytes returned.
- the st(v) syntax descriptor is only used in this Specification when the current position in the bitstream is a byte-aligned position.
- -tu(v) A function that decodes a syntax element encoded in truncated unary code (using up to maxVal bits with maxVal defined in the semantics of the symtax element).
- -u(n) A function that decodes a syntax element coded as an unsigned integer using n bits. If n is "v" in the syntax table, the corresponding number of bits may vary depending on the values of other syntax elements.
- the parsing process for this descriptor can be specified by the return value of the read_bits(n) function where the most significant bit (MSB) written first is interpreted as a binary representation of an unsigned integer. (unsigned integer using n bits. When n is "v” in the syntax table, the number of bits varies in a manner dependent on the value of other syntax elements.
- the parsing process for this descriptor is specified by the return value of the function read_bits( n ) interpreted as a binary representation of an unsigned integer with the most significant bit written first).
- -ue(v) a function that decodes a syntax element encoded with unsigned 0th order Exp-Golomb
- the parsing process for this descriptor can be specified with k order equal to 0. (unsigned integer 0-th order Exp-Golomb-coded syntax element with the left bit first.
- the parsing process for this descriptor is specified with the order k equal to 0).
- the intra prediction modes may include two non-directional intra prediction modes and 65 directional prediction modes.
- the non-directional intra prediction modes may include a planar intra prediction mode and a DC intra prediction mode, and the directional intra prediction modes may include intra prediction modes numbered 2 to 66.
- 5 exemplarily shows 65 directional intra prediction modes.
- intra prediction modes having horizontal directionality and intra prediction modes having vertical directionality can be distinguished centering on intra prediction mode 34 having an upward-left diagonal prediction direction. That is, intra prediction modes 2 to 33 have a horizontal direction, and intra prediction modes 34 to 66 have a vertical direction.
- the 18th intra prediction mode and the 50th intra prediction mode represent a horizontal intra prediction mode and a vertical intra prediction mode, respectively, and the second intra prediction mode is a downward-left diagonal intra prediction mode,
- the 34th intra prediction mode may represent an upper-left diagonal intra prediction mode, and the 66th intra prediction mode may represent an upper-left diagonal intra prediction mode.
- the non-directional intra prediction modes may include a planar intra prediction mode of number 0 and a DC intra prediction mode of number 1.
- the transform unit may correspond to the transform unit in the above-described encoding device of FIG. 2, and the inverse transform unit may correspond to the above-described inverse transform unit in the encoding apparatus of FIG. 2 or the inverse transform unit in the decoding apparatus of FIG. 3. .
- the transform unit may derive (primary) transform coefficients by performing a primary transform based on residual samples (residual sample array) in the residual block (S610).
- the primary transform may be referred to as a core transform.
- the primary transform may be based on adaptive multiple transform selection (MTS), and when adaptive multiple transform is applied as the primary transform, it will be referred to as an adaptive multiple core transform.
- MTS adaptive multiple transform selection
- the adaptive multi-core transform may represent a transform method by additionally using Discrete Cosine Transform (DCT) Type 2, Discrete Sine Transform (DST) Type 7, DCT Type 8, and/or DST Type 1. That is, the adaptive multicore transform converts a residual signal (or residual block) in the spatial domain based on a plurality of transform kernels selected from among the DCT type 2, the DST type 7, the DCT type 8, and the DST type 1.
- a transformation method for transforming into transform coefficients (or first-order transform coefficients) of the frequency domain may be indicated.
- DCT type 2, DST type 7, DCT type 8, and DST type 1 may be referred to as conversion types, conversion kernels, or conversion cores.
- These DCT/DST transform types may be defined based on basis functions, and the basis functions may be represented as shown in the following table.
- a vertical transform kernel and a horizontal transform kernel for the target block may be selected from among the transform kernels, and vertical transform for the target block is performed based on the vertical transform kernel.
- horizontal transformation of the target block may be performed based on the horizontal transformation kernel.
- the horizontal transformation may represent transformation of horizontal components of the target block
- the vertical transformation may represent transformation of vertical components of the target block.
- a vertical transformation or a horizontal transformation is performed, which basis functions are applied are combined to form a mapping relationship for a transformation kernel.
- a horizontal conversion kernel is denoted by trTypeHor and the vertical conversion kernel is denoted by trTypeVer
- a trTypeHor or trTypeVer value of 0 is set to DCT2
- a trTypeHor or trTypeVer value of 1 is set to DST7
- a trTypeHor or trTypeVer value of 2 may be set to DCT8.
- MTS index information may be encoded and signaled to the decoding device to indicate one of a plurality of conversion kernel sets. For example, if the MTS index is 0, it indicates that both trTypeHor and trTypeVer values are 0, if the MTS index is 1, it indicates that both trTypeHor and trTypeVer values are 1, and if the MTS index is 2, the trTypeHor value is 2 and the trTypeVer value indicates that trTypeHor is 1 and trTypeVer is 2 when the MTS index is 3, and trTypeHor and trTypeVer are both 2 when the MTS index is 4.
- a conversion kernel set according to MTS index information is shown in a table as follows.
- the transform unit may derive modified (secondary) transform coefficients by performing secondary transform on the basis of the (primary) transform coefficients (S620). If the first transform is a transform from the spatial domain to the frequency domain, the second transform can be regarded as a transform from the frequency domain to the frequency domain.
- the second-order transform means transforming into a more compressed expression by using a correlation existing between (first-order) transform coefficients.
- the secondary transform may include a non-separable transform. In this case, the secondary transform may be referred to as a non-separable secondary transform (NSST) or a mode-dependent non-separable secondary transform (MDNSST).
- the non-separable secondary transform is the modified transform coefficients for the residual signal by secondary transforming the (first-order) transform coefficients derived through the primary transform based on a non-separable transform matrix. (or quadratic transform coefficients).
- a non-separable transform matrix or quadratic transform coefficients.
- non-separate quadratic transformation rearranges two-dimensional signals (transform coefficients) into one-dimensional signals through a specific direction (eg, a row-first direction or a column-first direction), and then , modified transform coefficients (or secondary transform coefficients) may be derived based on matrix operation of the one-dimensional vector and the non-separate transform matrix.
- the row priority order is to arrange the 1st row, the 2nd row, ... , the Nth row for the MxN block
- the column priority order is the 1st column, the 2nd row for the MxN block.
- Column, ... to arrange them in a row in the order of the Mth column. That is, for the non-separate quadratic transformation, the transform coefficients derived through the primary transformation may be arranged in a 1-dimensional vector according to the row-major direction and then subjected to a matrix operation, or arranged in a 1-dimensional vector in the column-major direction. After that, matrix operations may be performed.
- the non-separate secondary transform may be applied to a top-left region of a block composed of (primary) transform coefficients (hereinafter referred to as a transform coefficient block or a transform block).
- a transform coefficient block or a transform block For example, when both the width (W) and the height (H) of the transform coefficient block are 8 or more, an 8x8 non-separate secondary transform may be applied to an 8x8 region at the upper left of the transform coefficient block.
- a 4 ⁇ 4 non-separate quadratic Transformation may be applied to the upper left min(8,W) ⁇ min(8,H) region of the transform coefficient block.
- the embodiment is not limited to this, and for example, even if only the condition that both the width (W) or the height (H) of the transform coefficient block are 4 or more is satisfied, a 4 ⁇ 4 non-separate secondary transform is applied to the upper left corner of the transform coefficient block. It may also be applied to the min(8,W) ⁇ min(8,H) region.
- a non-separate secondary transform may be applied to a 4x4 or 8x8 region at the upper left of the transform block according to the size of the transform block.
- a transformation for an upper left 4 ⁇ 4 area may be named a 4 ⁇ 4 transformation
- a transformation for an upper left 8 ⁇ 8 area may be referred to as an 8 ⁇ 8 transformation.
- the non-separate secondary transform may be performed as follows.
- the 4 ⁇ 4 input block X may be expressed as Equation 1 below.
- a vector may be equal to Equation 2 below.
- the second-order non-separate transform can be calculated as in Equation 3 below.
- T denotes a 16 ⁇ 16 (non-separate) transformation matrix, and means multiplication of a matrix and a vector.
- 16 ⁇ 1 conversion coefficient vector through Equation 3 above can be derived, and the may be re-organized into a 4 ⁇ 4 block through a scan order (horizontal, vertical, diagonal, etc.).
- HyGT Hypercube-Givens Transform
- the above-described calculation is an example, and HyGT (Hypercube-Givens Transform) may be used to calculate the non-separate quadratic transform in order to reduce the calculation complexity of the non-separate quadratic transform.
- a transform kernel (or transform core or transform type) may be selected in a mode dependent manner.
- the mode may include an intra prediction mode and/or an inter prediction mode.
- two non-separate quadratic transform kernels can be configured per transform set for non-separate quadratic transforms for both the 8x8 transform and the 4x4 transform, and the transform set is four.
- 4 transform sets may be configured for 8x8 transforms
- 4 transform sets may be configured for 4x4 transforms.
- each of the four transformation sets for the 8 ⁇ 8 transformation may include two 8 ⁇ 8 transformation kernels
- each of the four transformation sets for the 4 ⁇ 4 transformation may include two 4 ⁇ 4 transformation kernels.
- the size of the transform that is, the size of the region to which the transform is applied, may be a size other than 8 ⁇ 8 or 4 ⁇ 4 as an example, the number of sets is n, and the number of transform kernels in each set is k. It could be a dog.
- the transform set may be referred to as an NSST set or an LFNST set. Selection of a specific set among the transform sets may be performed, for example, based on the intra prediction mode of the current block (CU or subblock).
- a low-frequency non-separable transform (LFNST) may be an example of a simplified separable transform (RST) to be described later, and represents a non-separate transform for a low frequency component.
- mapping of four transform sets according to intra prediction modes may be represented as shown in Table 3 below, for example.
- intra prediction modes can be mapped to any one of four transform sets, that is, lfnstTrSetIdx from 0 to 3 or 4.
- one of k transform kernels in the specific set may be selected through a non-separate secondary transform index.
- the encoding device may derive a non-separable secondary transform index indicating a specific transform kernel based on a rate-distortion (RD) check, and may signal the non-separate secondary transform index to the decoder.
- the decoding device may select one of k transform kernels in a specific set based on the non-separate secondary transform index.
- lfnst index value 0 can point to the first non-separate quadratic transform kernel
- lfnst index value 1 can point to the second non-separate quadratic transform kernel
- lfnst index value 2 to the third non-separate quadratic transform kernel.
- the lfnst index value 0 may indicate that the first non-separate secondary transform is not applied to the target block
- the lfnst index values 1 to 3 may indicate the three transform kernels.
- the transform unit may perform the non-separate quadratic transform based on the selected transform kernels and obtain modified (secondary) transform coefficients.
- the modified transform coefficients may be derived as quantized transform coefficients through a quantization unit, encoded, and transmitted to a signaling device for signaling to a decoding device and an inverse quantization/inverse transformation unit within an encoding device.
- the (primary) transform coefficients that are outputs of the primary (separate) transform can be derived as quantized transform coefficients through the quantization unit as described above, and are encoded. It may be transmitted to the inverse quantization/inverse transform unit in the signaling and encoding device to the decoding device.
- the inverse transformation unit may perform a series of procedures in the reverse order of the procedures performed by the above-described transformation unit.
- the inverse transform unit receives the (inverse quantized) transform coefficients, performs a secondary (inverse) transform, derives (first) transform coefficients (S630), and performs a first (inverse) transform on the (primary) transform coefficients.
- Residual blocks may be obtained by performing transformation (S640).
- the primary transform coefficients may be referred to as modified transform coefficients from the point of view of the inverse transform unit.
- the encoding device and the decoding device may generate a reconstructed block based on the residual block and the predicted block and generate a reconstructed picture based on the residual block.
- the inverse transform unit applies a transform kernel matrix to the (inverse quantized) transform coefficients arranged in a specific order, for example, in a diagonal scan order (specifically, a diagonal scan order starting from the upper left corner of the transform block and proceeding in the lower right direction)
- a modified transform coefficient can be derived.
- the modified transform coefficients may be arranged in two dimensions in the upper left region of the transform block according to the direction in which the transform coefficients are read for the secondary transform in the transform unit, that is, the row-first direction or the column-first direction.
- the inverse transform unit may align the modified transform coefficients in the 4 ⁇ 4 area of the transform block in two dimensions, and when the transform unit performs the 8 ⁇ 8 transform, the inverse transform unit may arrange the transform coefficients of the transform block.
- the modified transform coefficients in the 8 ⁇ 8 area can be arranged in two dimensions.
- the secondary inverse transform may be NSST, reduced secondary transform (RST), or LFNST, and whether to apply the secondary inverse transform may be determined based on a secondary transform flag parsed from a bitstream. As another example, whether to apply the secondary inverse transform may be determined based on transform coefficients of the residual block.
- This second order inverse transform (i.e. transform kernel, transform matrix or transform kernel matrix) may be determined based on the set of LFNST (NSST or RST) transforms specified according to the intra prediction mode.
- the secondary transform determination method may be determined depending on the primary transform determination method. Depending on the intra prediction mode, various combinations of primary and secondary transforms may be determined. Also, for example, a region to which a secondary inverse transform is applied may be determined based on the size of the current block.
- a residual block (residual samples) may be obtained by receiving (inverse quantized) transform coefficients and performing the primary (separate) inverse transform.
- the encoding device and the decoding device may generate a reconstructed block based on the residual block and the predicted block and generate a reconstructed picture based on the residual block.
- a reduced secondary transform (RST) with a reduced size of a transformation matrix (kernel) can be applied in the concept of NSST in order to reduce the amount of computation and memory required for non-separate secondary transformation.
- RST reduced secondary transform
- kernel transformation matrix
- LFNST low-frequency non-separable transform
- LFNST may mean a transform performed on residual samples of a target block based on a transform matrix having a reduced size.
- the simplified transformation is performed, the amount of computation required for transformation may be reduced due to the reduction in the size of the transformation matrix. That is, LFNST can be used to solve the computational complexity issue that occurs when transforming large blocks or non-separate transforms.
- the inverse transform unit 235 of the encoding apparatus 200 and the inverse transform unit 322 of the decoding apparatus 300 modify transforms based on the inverse RST of transform coefficients. It may include an inverse RST unit for deriving coefficients, and an inverse primary transform unit for deriving residual samples for the target block based on inverse primary transform for modified transform coefficients.
- the inverse primary transform means an inverse transform of the primary transform applied to the residual.
- deriving a transform coefficient based on a transform may mean deriving a transform coefficient by applying a corresponding transform.
- FIG. 7 is a diagram for explaining RST or LFNST to which RST is applied according to an embodiment of the present document.
- a “target block” may mean a current block, residual block, or transform block on which coding is performed.
- a reduced transformation matrix may be determined by mapping an N dimensional vector to an R dimensional vector located in another space, where R is less than N.
- N may mean the square of the length of one side of a block to which a transform is applied or the total number of transform coefficients corresponding to a block to which a transform is applied
- the simplification factor may mean an R/N value.
- the simplification factor may be referred to by various terms such as reduced factor, reduction factor, reduced factor, reduction factor, simplified factor, and simple factor.
- R may be referred to as a reduced coefficient, but in some cases, a reduced factor may mean R.
- the simplification factor may mean an N/R value.
- the size of the simplified transform matrix according to an embodiment is RxN smaller than the size NxN of the normal transform matrix, and can be defined as in Equation 4 below.
- the matrix T in the reduced transform block shown in (a) of FIG. 7 may mean the matrix T RxN of Equation 4. As shown in (a) of FIG. 7 , when residual samples of the target block are multiplied by the simplified transform matrix T RxN , transform coefficients of the target block may be derived.
- the RST according to (a) of FIG. 7 is as follows It can be expressed as a matrix operation such as Equation 5. In this case, the memory and multiplication operation can be reduced to approximately 1/4 by the simplification factor.
- matrix operation can be understood as an operation that obtains a column vector by placing the matrix on the left of the column vector and multiplying the matrix by the column vector.
- r 1 to r 64 may represent residual samples of the target block, and more specifically, may be transform coefficients generated by applying a primary transform.
- transform coefficients c i for the target block may be derived, and the process of deriving c i may be the same as Equation 6.
- the size of the normal transformation matrix is 64x64 (NxN), but the size of the simplified transformation matrix is reduced to 16x64 (RxN).
- Memory usage can be reduced by R/N ratio.
- the number of multiplication operations can be reduced (RxN) at an R/N ratio when a simplified transformation matrix is used.
- the transform unit 232 of the encoding apparatus 200 may derive transform coefficients for the target block by performing a primary transform and an RST-based secondary transform on residual samples of the target block. These transform coefficients may be delivered to the inverse transform unit of the decoding device 300, and the inverse transform unit 322 of the decoding device 300 derives modified transform coefficients based on the inverse reduced secondary transform (RST) of the transform coefficients. and derive residual samples for the target block based on the inverse primary transform of the modified transform coefficients.
- RST inverse reduced secondary transform
- the size of the inverse RST matrix T NxR is NxR smaller than the size NxN of a normal inverse transform matrix, and has a transpose relationship with the simplified transform matrix T RxN shown in Equation 4.
- the matrix T t in the Transform block may mean an inverse RST matrix T RxN T (the superscript T means transpose).
- T means transpose
- modified transform coefficients of the target block or residual samples of the target block may be derived.
- the inverse RST matrix T RxN T may be expressed as (T RxN ) T NxR .
- modified transform coefficients for the target block may be derived when transform coefficients for the target block are multiplied by the inverse RST matrix T RxN T .
- an inverse RST may be applied as an inverse primary transform.
- residual samples of the target block may be derived by multiplying the transform coefficients of the target block by the inverse RST matrix T RxN T .
- the inverse RST according to (b) of FIG. 7 is It can be expressed as a matrix operation such as Equation 7 below.
- Equation 7 c 1 to c 16 may represent transform coefficients of the target block, that is, transform coefficients derived through residual coding.
- r i representing modified transform coefficients of the target block or residual samples of the target block may be derived, and the process of deriving r i may be the same as Equation 8.
- Equation 8 r 1 to r N representing modified transform coefficients of the target block or residual samples of the target block may be derived. Since N is 64 in Equation 7, 64 modified transform coefficients can be derived through Equation 8.
- the size of the normal inverse transformation matrix is 64x64 (NxN), but the size of the simplified inverse transformation matrix is reduced to 64x16 (NxR).
- memory usage can be reduced by R/N ratio.
- NxR the number of multiplication operations
- a simplified inverse transform matrix or inverse transform matrix may also be named a simplified transform matrix or a transform matrix if it is not confusing whether it is a transform or an inverse transform.
- a maximum of 16 x 48 transformation kernel is obtained by selecting only 48 data instead of a 16 x 64 transformation kernel matrix for 64 data constituting an 8 x 8 area. matrix can be applied.
- maximum means that the maximum value of m is 16 for an m x 48 transform kernel matrix capable of generating m coefficients.
- m coefficients can be generated by receiving 48 pieces of data.
- m 16 data are input and 16 coefficients are generated. That is, assuming that 48 pieces of data form a 48 x 1 vector, a 16 x 1 vector can be generated by sequentially multiplying a 16 x 48 matrix and a 48 x 1 vector.
- the column vectors of Equation 8 are r 1 to r 48
- the size of the transform matrix is 16x48
- 16 modified transform coefficients (c 1 to c 16 ) are derived through matrix operation.
- a 48 x 1 vector can be formed by appropriately arranging 48 pieces of data constituting an 8 x 8 area.
- a 48 x 1 vector may be constructed based on 48 pieces of data constituting an area excluding the 4 x 4 area at the bottom right of the 8 x 8 area.
- 16 modified transformation coefficients are generated.
- the 16 modified transformation coefficients can be arranged in the upper left 4 x 4 area according to the scanning order and the upper right area.
- the 4 x 4 area and the lower left 4 x 4 area can be filled with zeros.
- a transposed matrix of the transformation kernel matrix described above may be used. That is, when inverse RST or inverse LFNST is performed as an inverse transformation process performed by the decoding device, the input coefficient data to which inverse RST is applied is composed of a 1-dimensional vector according to a predetermined arrangement order (diagonal scanning order), and the 1-dimensional vector
- the modified coefficient vector obtained by multiplying the corresponding inverse RST matrix from the left side may be arranged in a two-dimensional block according to a predetermined arrangement order.
- the size of the transformation matrix of Equation 7 is 48 x 16
- the column vectors are c 1 to c 16
- the nx1 vector can be interpreted in the same sense as an nx1 matrix, it can also be expressed as an nx1 column vector.
- * means matrix multiplication operation.
- 48 modified transform coefficients can be derived, and the 48 modified transform coefficients can be arranged in the upper left, upper right, and lower left areas of the 8x8 area except for the lower right area.
- the encoding device is based on various coding methods such as exponential Golomb, context-adaptive variable length coding (CAVLC), or context-adaptive binary arithmetic coding (CABAC) to the value or residual of a syntax element.
- a bitstream may be derived by encoding quantized values of transform coefficients of
- the decoding device decodes the bitstream based on various coding methods such as exponential Golomb coding, CAVLC, or CABAC to derive values of syntax elements required for image reconstruction or quantized values of transform coefficients related to residuals. .
- the above-described coding methods may be performed as described below.
- CABAC context-adaptive binary arithmetic coding
- the encoding device may convert the input signal into a binary value by binarizing the value of the input signal.
- the input signal already has a binary value (ie, when the value of the input signal is a binary value)
- the input signal may be used as it is without performing binarization.
- each binary number 0 or 1 constituting the binary value may be referred to as a bin.
- each of 1, 1, and 0 may be represented as one bin.
- the bin(s) for one syntax element may represent the value of the syntax element.
- Such binarization may be based on various binarization methods such as a truncated rice binarization process or a fixed-length binarization process, and a binarization method for a target syntax element may be predefined.
- the binarization process may be performed by a binarization unit in an entropy encoding unit.
- the binarized bins of the syntax element may be input to a regular coding engine or a bypass coding engine.
- the regular coding engine of the encoding device may allocate a context model reflecting a probability value to a corresponding bin, and encode the corresponding bin based on the allocated context model.
- the regular coding engine of the encoding device may update a context model for a corresponding bin after performing coding for each bin. Bins coded as described above may be referred to as context-coded bins.
- binarized bins of the syntax element when binarized bins of the syntax element are input to the bypass coding engine, they may be coded as follows.
- the bypass coding engine of the encoding device may omit a process of estimating a probability for an input bin and a process of updating a probability model applied to the bin after coding.
- the encoding device may code input bins by applying a uniform probability distribution instead of allocating a context model, thereby improving encoding speed.
- a bin coded as described above may be referred to as a bypass bin.
- Entropy decoding may represent a process of performing the same process as the above-described entropy encoding in reverse order.
- a decoding device may decode encoded image/video information.
- the image/video information may include partitioning related information, prediction related information (eg, inter/intra prediction classification information, intra prediction mode information, inter prediction mode information, etc.), residual information or in-loop filtering related information, and the like. , or various syntax elements related thereto.
- the entropy coding may be performed in units of syntax elements.
- the decoding device may perform binarization on target syntax elements.
- the binarization may be based on various binarization methods such as a truncated rice binarization process or a fixed-length binarization process, and a binarization method for a target syntax element may be predefined.
- the decoding device may derive available empty strings (empty string candidates) for available values of target syntax elements through the binarization procedure.
- the binarization process may be performed by a binarization unit in an entropy decoding unit.
- the decoding device may compare the derived bin string with available bin strings for corresponding syntax elements while sequentially decoding or parsing bins for the target syntax elements from the input bit(s) in the bitstream. If the derived bin string is equal to one of the available bin strings, a value corresponding to the bin string is derived as the value of the corresponding syntax element. If not, the above-described procedure may be performed again after further parsing the next bit in the bitstream. Through this process, the corresponding information can be signaled using variable length bits without using a start bit or an end bit for specific information (or specific syntax element) in the bitstream. Through this, relatively fewer bits can be allocated for low values, and overall coding efficiency can be increased.
- the decoding device may perform context model-based or bypass-based decoding of each bin in the bin string from a bitstream based on an entropy coding technique such as CABAC or CAVLC.
- a decoding device may receive a bin corresponding to the syntax element through a bitstream, and may receive the syntax element and decoding information of a block to be decoded or a neighboring block or decoding in a previous step.
- a context model may be determined using information of the received symbol/bin, and an occurrence probability of the received bin may be predicted according to the determined context model, and arithmetic decoding of the bin may be performed to perform the bin arithmetic decoding. Values of syntax elements can be derived.
- a context model of a bin to be decoded next may be updated based on the determined context model.
- the context model may be allocated and updated for each bin that is context-coded (regular coding), and the context model may be indicated based on a context index (ctxIdx: context index) or a context index increment (ctxInc: context index increment).
- ctxIdx may be derived based on ctxInc.
- ctxIdx representing the context model for each of the normally coded bins may be derived as the sum of ctxInc and a context index offset (ctxIdxOffset).
- the ctxInc may be derived differently for each bin.
- the ctxIdxOffset may be represented by the lowest value of the ctxIdx.
- the ctxIdxOffset may be a value generally used to distinguish context models for other syntax elements, and a context model for one syntax element may be identified or derived based on ctxInc.
- Entropy decoding may perform the same process as entropy encoding in reverse order.
- the decoding device may receive a bin corresponding to the syntax element through a bitstream, and may decode the input bin by applying a uniform probability distribution. .
- the decoding device may omit a procedure of deriving a context model of a syntax element and a procedure of updating a context model applied to the bin after decoding.
- DCT type 2, DST type 7, and DCT type 8 are based on the residual signal (or residual block).
- First-order transform from the spatial domain to the frequency domain was applied to generate transform coefficients (or first-order transform coefficients).
- This adaptive multiple core transformation was a form of separation transformation in which one kernel was applied in the horizontal direction and one kernel was applied in the vertical direction.
- non-separation transformation provides higher coding efficiency than separation transformation (kernel). Accordingly, hereinafter, various embodiments related to a primary transform including a separative transform and a non-separate transform are proposed.
- the primary transform may include a non-separate transform.
- a DCT type 2 and a non-separate (first-order) transform kernel may be used for the first transform.
- a non-separate (first-order) transform kernel may be used in addition to existing DCT type 2, DST type 7, and DCT type 8.
- one or more kernels of DCT type 2, DST type 7, and DCT type 8 may be replaced with a non-separate (first-order) transform kernel.
- this is only an example and can be applied to other cases where the configuration of the existing conversion kernel described above is different. That is, it can be applied even when other types of DCT/DST or transform skip are included.
- the non-separate primary transform may generate transform coefficients for the residual signal by transforming residual signals based on a non-separate transform matrix. That is, unlike conventional transformation methods in which vertical transformation and horizontal transformation are separately applied (or horizontal and vertical transformation are independently applied), transformation can be performed at once using the non-separate transformation matrix.
- the non-separate primary transform may be performed in the same manner as the non-separate secondary transform method described above with reference to FIG. 6 .
- the 4x4 input block X when the non-separate primary transform is applied to a 4x4 input block, the 4x4 input block X may be equal to Equation 1 above.
- a vector May be the same as Equation 2 above.
- the first-order non-separate transform can be calculated as in Equation 3 above.
- 16x1 transform coefficient vector through Equation 3 above can be derived, and the may be reconstructed into a 4x4 block according to a scan order (ex. horizontal, vertical, diagonal, or predetermined/stored scan order).
- a scan order ex. horizontal, vertical, diagonal, or predetermined/stored scan order.
- the above calculation is only an example, and non-separate transform calculation methods optimized for reducing the calculation complexity of the non-separate primary transform may be used.
- the transform set and kernel for the non-separate primary transform are the mode (ex. intra prediction mode, inter prediction mode, etc.), the width of the input block, the height of the input block, and the number of pixels of the input block. , a sub-block location within a block, an explicitly signaled syntax element (syntax element), statistical characteristics of neighboring pixels, whether or not a secondary transform is used, and the like. That is, the transform set and transform kernel for the non-separate primary transform are the mode (ex. intra prediction mode, inter prediction mode, etc.), the width of the input block, the height of the input block, and the pixels of the input block. It may be selected based on at least one of the number, sub-block position within a block, explicitly signaled syntax elements, statistical characteristics of neighboring pixels, and whether secondary transform is used.
- n sets may be grouped based on intra prediction modes, and k transform kernels may be included in each set.
- the number and grouping method of intra prediction modes are not limited to specific values and specific methods.
- the non-separate primary transform set and kernel may be determined based on the width and/or height of the input block. For example, for a 4x4 input block, n 1 sets and k 1 transform kernels may be included in each set, and for a 4x8 block, n 2 sets and k 2 transform kernels may be included in each set. It can be.
- non-separate transformation according to the width and height of the block may not be used. That is, for example, the block is divided into small blocks (i.e., sub-blocks) in the spatial domain, and the non-separation primary transform is performed according to the width and height of the divided small blocks (i.e., sub-blocks).
- the non-separative transformation is performed on a 4x8 block
- the 4x8 block is divided into two 4x4 sub-blocks in the spatial domain
- the 4x4 block-based primary non-separate transformation can be performed on each 4x4 sub-block.
- an 8x16 block may be divided into two 8x8 sub-blocks in the spatial domain, and the 8x8 block-based primary non-separation transform may be performed on each 8x8 sub-block.
- the transform unit may perform the non-separate primary transform based on the selected transform kernel and obtain transform coefficients.
- the acquired transform coefficients may be derived as transform coefficients quantized by a quantization unit with or without performing secondary transform.
- the quantized transform coefficients may be encoded and signaled to a decoding device, and the quantized transform coefficients may be transmitted to an inverse quantization/inverse transform unit in the encoding device.
- the inverse transformation unit may perform a series of procedures in the reverse order of the procedures performed by the above-described transformation unit.
- the inverse transform unit may obtain a residual block (residual samples) by receiving the (inverse quantized) transform coefficients and performing a secondary transform, or by performing the primary inverse transform without performing the secondary transform.
- the encoding device and the decoding device may generate a reconstructed block based on the residual block and the predicted block, and generate a reconstructed picture based on the reconstructed block.
- the primary transform to include a non-separate transform as in the above embodiment, a higher encoding efficiency can be expected than a conventional primary transform including only a separate transform.
- the primary transform when the primary transform includes both separative transform and non-separate transform, information related to the primary transform can be effectively signaled as follows.
- DCT type 2, DST type 7, DCT type 8, DCT type 5, DST type 4, DST type 1, IDT (identity transform), or other non-separate transforms are used in the primary transform based on the separative transform.
- Non-transformations (ex: transform skip) may be included.
- transform skip In the case of a separative transformation, there are generally several selectable transforms, and in the case of a non-separate transformation, the number of non-separate transformations that can be selected may be one or more because the computational complexity or memory requirements may be relatively higher than that of the separable transformation. .
- transform index information for the primary transform may be signaled as follows.
- the value of transformation index information may have the same meaning as a transformation index.
- a transform index for a non-separative transform may be set to 0, and a transform index for a separative transform may start from 1. That is, the value of transform index information related to non-separate transform kernels may be set to 0, and the values of transform index information related to separate transform kernels may start from 1.
- the value of the transform index information related to the one non-separate transform kernel is 0, and , values of transformation index information related to the M separate transformation kernels may be 1 to M.
- M may be a positive integer greater than 1.
- transformation index 0 when there are 5 possible separation transformations, transformation index 0 may indicate non-separation transformation, and transformation indices 1 to 5 may indicate predefined separation transformations. That is, when the number of separative transformation kernels is 5, transformation index information having a value of 0 may indicate non-separate transformation, and transformation index information having values from 1 to 5 may indicate predefined separative transformations, respectively. Accordingly, a conversion index value of any one of 0 to 5 may be signaled from an encoding device (encoder) to a decoding device (decoder).
- the decoding device can know whether a non-separate transform or a separate transform is used through the decoded (decoded) transform index, and can determine which of a plurality of separate transforms (kernels) is used. .
- the transformation index for the non-separative transformation may be set to a predefined N
- the value of the transform index information related to the one non-separate transform kernel is N
- the M separate transform kernels are Values of transformation index information related to transformation kernels may be 0 to N-1 and M to N+1.
- M may be a positive integer greater than 1
- N may be a positive integer smaller than M.
- the transform indices for the separable transform are assigned in a predetermined order from 0 to 5, but 3 is skipped.
- N the transform index for the non-separate transform
- the transform indices for the separable transform are assigned in a predetermined order from 0 to 5, but 3 is skipped.
- the values of transformation index information related to the separation transformation kernel are allocated in a predetermined order from 0 to 5.
- 3 can be skipped and allocated. Accordingly, a conversion index value of any one of 0 to 5 may be signaled from an encoding device (encoder) to a decoding device (decoder).
- the decoding device can know whether a non-separate transform or a separate transform is used through the decoded (decoded) transform index, and can determine which of a plurality of separate transforms (kernels) is used. .
- a flag indicating whether non-separate transform is used may be signaled before transform index information for the primary transform is signaled. For example, when the value of the flag indicating whether to use the non-separate transform is 0, transform index information for the separate transform can be additionally signaled. For example, when the value of the flag is 1, the transform index information for the primary transform can be signaled according to the above-described examples applied when the number of non-separate transform kernels is one and the number of separate transform kernels is multiple. there is.
- the encoded information may include a flag indicating whether a non-separate transform kernel is applied to the primary transform.
- the value 0 of the flag may indicate that the non-separate transform kernel is not applied to the primary transform, and the value 1 of the flag may represent that the non-separate transform kernel is applied to the primary transform.
- the transform index information for the primary transform may be related only to a separate transform kernel. In other words, if the value of the flag is 0, it indicates that the non-separate transform kernel is not applied to the primary transform, and thus the transform index information for the primary transform can be related only to the separative transform kernel.
- a value of a flag indicating whether non-separate transformation may be coded by predicting a probability through a context coded bin. That is, the flag may be context coded based on a context model.
- a context model for probability prediction may be configured using the size of the current block, the shape of the current block, an intra prediction mode applied to the current block, and/or information on previously coded blocks.
- transform index (or transform index related to a separate transform kernel) information may be binarized based on a fixed length coding (FLC) or a truncated binary code (TBC).
- FLC fixed length coding
- TBC truncated binary code
- the transform index may be coded based on context coding (context coding), for example, the transform index information may be coded based on context coding or bypass coding.
- the transform index (or transform index related to the separate transform kernel) value for the primary transform may be binarized based on FLC or TBC, and may be coded by treating it as a context coded bin or bypass coding. It can be coded through (bypass coding, that is, coding treated as a bypass coded bin).
- transform index information for the primary transform may be binarized based on a truncated unary code (TU code).
- TU code truncated unary code
- the transform index information may be coded based on context coding or bypass coding.
- the transform index value for the primary transform may be expressed through TU binarization, coded by predicting an occurrence probability through context coding, or coded with the same probability through bypass coding.
- transform index information for the primary transform may be signaled as follows.
- the value of the transform index information may have the same meaning as the transform index.
- a flag indicating whether to use non-separate transform may be signaled before signaling the transform index information for the primary transform. For example, when the value of the flag indicating whether to use the non-separative transform is 1, transform index information related to the non-separate transform kernel may be additionally signaled, and when the value of the flag is 0, the value associated with the separative transform kernel Conversion index information may be additionally signaled.
- the encoded information may include a flag indicating whether a non-separate transform kernel is applied to the primary transform.
- a value of 0 of the flag may indicate that a non-separate transform kernel is not applied to the primary transform
- a value of 1 of the flag may indicate that a non-separate transform kernel is applied to the primary transform.
- the transform index information for the primary transform may be related to a separate transform kernel
- transform index information for the primary transform may be associated with a non-separate transformation kernel.
- transform index information for the primary transform may be related to a separate transform kernel, and the value of the flag is Since a value of 1 indicates that a non-separate transform kernel is applied to the primary transform, the transform index information for the primary transform may be related to the non-separate transform kernel.
- the transform index information may be associated with a non-separate transform kernel.
- L and M may be positive integers greater than 1.
- transform index information related to a non-separate transform kernel or transform index information related to a separable transform kernel may be binarized based on FLC or TBC and coded based on context coding or bypass coding.
- transform index information related to the non-separate transform kernel or transform index information related to the separative transform kernel may be binarized based on FLC or TBC, and may be coded by treating it as a context coded bin or bypassing the context coded bin. It can be coded through coding (bypass coding, that is, coding treated as a bypass coded bin).
- transform index information related to the non-separate transform kernel or transform index information related to the separative transform kernel may be binarized based on TU code and coded based on context coding or bypass coding.
- the transform index information related to the non-separate transform kernel or the transform index information related to the separate transform kernel may be expressed through TU binarization, coded by predicting an occurrence probability through context coding, or bypass coding can be coded with the same probability through
- the value of the flag indicating whether non-separate transformation may be coded by predicting a probability through a context coded bin, as described above. That is, the flag may be context coded based on a context model.
- a context model for probability prediction may be configured using the size of the current block, the shape of the current block, an intra prediction mode applied to the current block, and/or information on previously coded blocks.
- the transform index information for all transform kernels applied to the primary transform may be signaled at once without separately signaling a flag indicating whether to use the non-separate transform.
- transformation index values 0 to L-1 may respectively indicate predetermined L non-separate transformation kernels, and from transformation index values L to L+M-1 may represent M separate conversion kernels, each of which is predetermined. That is, for example, transformation index values 0 to L-1 may correspond to non-separate transformation kernels 0 to L-1, and transformation index values L to L+M-1 may correspond to separative transformation kernels 0 to M-1.
- the value of transform index information related to the L non-separate transform kernels. may be 0 to L-1, and values of transform index information related to the M separate transform kernels may be L to L+M-1.
- L and M may be positive integers greater than 1.
- a method of mapping the transform index of the primary transform to an available separative transform kernel and a non-separate transform kernel can be variously applied in a predefined form other than the above-described case.
- the transform indexes related to the separative transform convert the transforms applied in the horizontal and vertical directions according to a predetermined rule. It can be signaled by determining.
- a transform index related to a separate transform may be separately transmitted as a separate transform index for a horizontal direction and a separate transform index for a vertical direction, and a transform designated by each transform index may be applied to the corresponding direction. .
- the first transform and the second transform can be efficiently applied as follows.
- separation transformation and non-separation transformation may be applied to the primary transformation, and the primary transformation based on separation transformation is DCT type 2, DST type 7, DCT type 8, DCT type 5, and DST type 4 , DST type 1, identity transform (IDT), or other non-separate transforms (ex: transform skip).
- a separate non-separate transform different from the first transform may be applied to the second transform.
- the non-separate transform since the non-separate transform has a higher computational complexity or memory requirement than the separative transform, when the non-separate transform is applied to the primary transform, the worst case for the application of the primary transform and the secondary transform It is necessary to control the computational complexity of the worst case.
- the use of the secondary transform which is a non-separate transform
- the bitstream may be parsed by considering only the case of the other separative transform or transform skip without considering the part where the non-separate transform occurs in the primary transform.
- a method of parsing transformation index information for the primary transformation may be dependent on whether or not the secondary transformation is applied. That is, when the decoding device (decoder) system first parses the transform index information for the primary transform, whether or not the transform index information for the secondary transform is parsed depends on the value of the transform index information for the primary transform. can be done
- the secondary transform which is a non-separate transform
- the transform index information for the primary transform may be restricted from being performed.
- the transform index information for the primary transform may be limited to be associated with a separate transform kernel.
- the restriction on the use of the secondary transform as in the above-described example may be applied according to the size of the block. For example, for a block of 16 ⁇ 16 or less, a restriction on the use of a secondary transform is not applied, and both a non-separate primary transform and a non-separate secondary transform may be applied.
- whether to apply the non-separate primary transform and the non-separate secondary transform to an arbitrary block may be predefined in an encoding device (encoder) and/or a decoding device (decoder) system.
- whether to apply the non-separate primary transform and the non-separate secondary transform may be determined according to the direction of the intra prediction mode of the corresponding transform block in addition to the size and shape of the block.
- the transform index information for the primary transform is related to a separate transform kernel. may be limited.
- the non-separate primary transform and the non-separate secondary transform are obtained through a distribution of values of decoded neighboring pixels used for intra prediction. application can be determined. For example, when the variance of neighboring pixel values is small, the non-separate primary transform may not be applied. In the case where the distribution of neighboring pixel values is very constant, there is a low probability that applying the non-separate transform will make a more accurate prediction than applying the separative transform, so separate signaling for the non-separate primary transform may not be performed. . That is, more efficient compression performance can be obtained by reducing the signaling overhead of information additionally required for the non-separate primary transform.
- a kernel transmission method when the primary transform includes both separative transform and non-separate transform, whether or not the non-separate primary transform is applied in the system and a kernel transmission method may be as follows.
- the non-separate first transform needs to predict the statistical characteristics of the residual signal, unlike the non-separate second transform, a generalized kernel for the non-separate first transform is obtained through a predefined finite kernel. Acquiring may be inefficient to reflect the diversity of each content.
- the non-separate secondary transform predicts the statistical characteristics of the primary transform coefficients, it can be designed relatively simply.
- a kernel suitable for given content may be derived from a decoding device (decoder) and used.
- a method of inducing a corresponding kernel in an encoding device (encoder) and transmitting it to a decoding device (decoder) may be used.
- the size of a block to which the non-separate primary transform is applied, a non-separate transform set related to an intra prediction mode of a current block, the number of kernels per set, and coefficient values per kernel may be transmitted.
- the number of kernels to be defined in advance may be very large because the statistical characteristics of the residual signal must be predicted in the non-separate primary transform. In this case, many bits are consumed to signal transform index information of kernels for the non-separate primary transform, and compression performance may be degraded.
- the predefined kernels for the non-separate primary transformation are classified into a plurality of lists (categories), and whether or not the kernels included in the specific list are applied to the non-separate primary transformation.
- Category information may be signaled at a higher level or a lower level. That is, for example, the category information may indicate whether a kernel applied to the non-separate primary transformation among kernels included in the corresponding category is included.
- the upper level may include sequence parameter set (SPS), picture parameter set (PPS), video parameter set (VPS), picture header (PH), slice header (SH), and the like
- the lower level may include CTU. (coding tree unit), CU (coding unit), TU (transform unit), and the like.
- category information is transmitted at a higher level (ex: SPS, PPS, VPS, PH, or SH), and at a lower level (CTU, CU, or TU), conversion index information for kernels existing in the category can transmit.
- category information may be transmitted in units of one or more CTUs, and transformation index information for kernels within a corresponding category may be transmitted at a lower block level (one or more CUs or TUs).
- category information may be derived by analyzing coding information or statistical characteristics of a region (e.g. tile, slice, CTU, CU) to which the category information is applied.
- the size, shape, prediction mode e.g. prediction mode within a picture
- transformation information e.g. separative transform or non-separate transform, DCT-2/DCT-7/DCT Category information may be derived through -8/DCT-5/DST-4/DST-1, identity transform (IDT), etc.
- category information can be derived.
- the above-mentioned category information can of course be derived in the decoding device.
- the encoded information may include category information related to a category to which a transform kernel applied to the primary transform belongs among a plurality of categories into which a plurality of transform kernels are classified.
- the category information may be transmitted at a higher level
- the transformation index information for the primary transformation may be transmitted at a lower level.
- the upper level is one of Sequence Parameter Set (SPS), Picture Parameter Set (PPS), Video Parameter Set (VPS), Picture Header (PH), and Slice Header (SH)
- the lower level is CTU. It may be one of (Coding tree unit), Coding unit (CU), and Transform unit (TU).
- FIGS. 9 and 10 schematically illustrate an example of a video/image encoding method and related components according to the embodiment(s) of this document.
- the method disclosed in FIG. 9 may be performed by the encoding device disclosed in FIG. 2 .
- S900 to S930 of FIG. 9 may be performed by the residual processing unit 230 of the encoding device 200 of FIG. 2, and S940 of FIG. 9 is the entropy encoding unit of the encoding device 200 ( 240) can be performed.
- the method disclosed in FIG. 9 may include the embodiments described above in this document.
- the encoding apparatus 200 derives residual samples for a current block (S900). For example, the encoding apparatus 200 may derive prediction samples for the current block and derive residual samples for the current block based on the derived prediction samples.
- the encoding device 200 derives transform coefficients by performing a primary transform based on the transform kernel (S910).
- the encoding apparatus 200 may derive transform coefficients for the current block by performing a primary transform on the residual samples based on a transform kernel.
- the transform kernel may be a transform kernel applied to the primary transform among a plurality of transform kernels and may be referred to as a transform matrix.
- the transform kernel may be selected based on an intra prediction mode from among the plurality of transform kernels.
- the conversion kernel may be any one of a non-separation conversion kernel and a separation conversion kernel.
- the encoding device 200 generates transform index information related to the transform kernel (S920). For example, the encoding device 200 may generate transform index information related to the transform kernel among the plurality of transform kernels.
- the encoding device 200 generates residual information based on transform coefficients (S930). That is, for example, the encoding apparatus 200 may generate residual information based on the transform coefficients of the current block derived by performing the primary transform.
- S930 performs secondary transform, which is a non-separate transform, on the transform coefficients, thereby deriving modified transform coefficients for the current block and the It may include generating residual information based on the modified transform coefficients. That is, for example, when the transform index information is related to a separate transform kernel, the encoding device 200 derives modified transform coefficients for the current block by performing secondary transform, which is a non-separate transform, on the transform coefficients. and generate the residual information based on the modified transform coefficients.
- the encoding apparatus 200 may derive the transform coefficients by applying LFNST to the transform coefficients based on the LFNST matrix.
- the LFNST may be a quadratic transform, and may include a non-separate secondary transform in which the RST is reflected.
- the LFNST matrix applied to the secondary transformation may be a non-square matrix in which the number of rows is less than the number of columns.
- the encoding apparatus 200 may derive quantized transform coefficients by performing quantization on the modified transform coefficients, and generate residual information about the quantized transform coefficients.
- the residual information may include the above-described conversion-related information/syntax elements such as LFNST-related information.
- the encoding device 200 encodes image information (S940).
- the encoding device 200 may encode image information including the transform index information and the residual information.
- the image information may further include prediction-related information related to prediction samples of the current block.
- the video/image information may include various information according to an embodiment of the present document.
- the video/image information may include information for picture restoration.
- the information for picture reconstruction may include information related to prediction, information related to transformation, and information related to filtering.
- Encoded video/image information may be output in the form of a bitstream.
- the bitstream may be transmitted to a decoding device through a network or a storage medium.
- the plurality of transform kernels may include a separate transform kernel and a non-separate transform kernel.
- the plurality of transform kernels may include one non-separate transform kernel and M separate transform kernels.
- the value of the transform index information related to the one non-separate transform kernel is 0, the values of the transform index information related to the M separate transform kernels range from 1 to M, and M is a positive value greater than 1. can be an integer.
- the value of the transform index information associated with the one non-separate transform kernel is N
- the values of the transform index information associated with the M separate transform kernels are 0 to N-1 and N+1 to M
- M is a positive integer greater than 1
- N may be a positive integer smaller than M.
- the plurality of transform kernels may include L non-separate transform kernels and M separate transform kernels.
- the values of the transform index information related to the L non-separate transform kernels are 0 to L-1
- the values of the transform index information related to the M separate transform kernels are L to L+M-1
- L and M may be positive integers greater than 1.
- the image information may further include a flag indicating whether a non-separate transform kernel is applied to the primary transform.
- the transformation index information may be associated with a separation transformation kernel.
- the transform index information is the one non-separate transform kernel or the M It can be associated with any one of the separate transformation kernels.
- the transformation index information may be related to a separation transformation kernel.
- the plurality of transform kernels include L non-separate transform kernels and M separate transform kernels, and the value of the flag is 1, the transform index information may be related to the non-separate transform kernel.
- the flag may be context coded based on a context model.
- the context model may be determined based on the size of the current block, the shape of the current block, an intra prediction mode applied to the current block, and information on previously coded blocks.
- the transform index information may be binarized based on a fixed length coding (FLC) or a truncated binary code (TBC).
- FLC fixed length coding
- TBC truncated binary code
- the transform index information may be coded based on context coding or bypass coding.
- the transformation index information may be binarized based on a truncated unary code.
- the transform index information may be coded based on context coding or bypass coding.
- the secondary transform may be restricted not to be performed.
- the transform index information is a separate transform kernel. may be related to
- the image information may further include category information related to a category to which a transform kernel applied to the primary transform belongs among a plurality of categories into which the plurality of transform kernels are classified. .
- the category information may be transmitted at a higher level, and the conversion index information may be transmitted at a lower level.
- the upper level may be one of a sequence parameter set (SPS), a picture parameter set (PPS), a video parameter set (VPS), a picture header (PH), and a slice header (SH).
- the lower level may be one of a coding tree unit (CTU), a coding unit (CU), and a transform unit (TU).
- FIG. 11 and 12 schematically illustrate an example of a video/image decoding method and related components according to an embodiment of the present document.
- the method disclosed in FIG. 11 may be performed by the decoding device disclosed in FIG. 3 .
- S1100 of FIG. 11 may be performed by the entropy decoding unit 310 of the decoding device 300
- S1110 and S1120 may be performed by the residual processing unit 320 of the decoding device 300
- S1130 may be performed by the adder 340.
- the method disclosed in FIG. 11 may include the embodiments described above in this document.
- the decoding device 300 obtains image information through a bitstream (S1100).
- the decoding device 300 may receive/obtain video/image information through a bitstream.
- the video/image information may include residual information and transformation index information.
- the video/image information may further include prediction-related information.
- the video/image information may include various information according to an embodiment of the present document.
- the video/image information may include information for picture reconstruction.
- the information for picture reconstruction may include information related to prediction, information related to transformation, and information related to filtering.
- the decoding device 300 derives transform coefficients based on the residual information (S1110). For example, the decoding apparatus 300 may derive transform coefficients for the current block based on the residual information. For example, the decoding apparatus 300 may derive quantized transform coefficients for the current block from the residual information. Also, the decoding apparatus 300 may derive transform coefficients for the current block by performing inverse quantization on the quantized transform coefficients. Also, for example, the residual information may include the above-described conversion related information/syntax elements such as LFNST related information.
- the decoding device 300 derives residual samples by performing a primary transform using a transform kernel (S1120).
- the decoding apparatus 300 derives residual samples for the current block by performing a primary transform using a transform kernel related to the transform index information among a plurality of transform kernels based on the transform coefficients.
- the transform kernel may be a transform kernel applied to the primary transform among a plurality of transform kernels and may be referred to as a transform matrix.
- the transform kernel may be selected based on an intra prediction mode from among the plurality of transform kernels.
- the conversion kernel may be any one of a non-separation conversion kernel and a separation conversion kernel.
- the primary transform may be an inverse primary transform.
- S1120 may include deriving modified transform coefficients for the current block by performing secondary transform, which is a non-separate transform, on the transform coefficients and the transform index for the modified transform coefficients. and deriving residual samples for the current block by performing the primary transform using a transform kernel related to information.
- secondary transform which is a non-separate transform
- the decoding apparatus 300 may derive the modified transform coefficients by applying LFNST to the transform coefficients based on the LFNST matrix.
- the LFNST may be a quadratic (inverse) transform, and may include a non-separate quadratic (inverse) transform in which the RST is reflected.
- the LFNST matrix applied to the quadratic (inverse) transformation may be a non-square matrix in which the number of columns is less than the number of rows.
- the decoding device 300 generates reconstruction samples for the current block (S1130). For example, the decoding apparatus 300 may generate reconstruction samples for the current block based on the residual samples. Also, the decoding device 300 may generate a reconstructed picture including the reconstructed samples based on the residual samples. Also, the decoding device 300 may generate a modified reconstructed picture by applying various filtering methods to the reconstructed picture. The modified reconstructed picture may be stored as an output and/or decoded picture buffer or memory 360 as a decoded picture, and may be used as a reference picture in an inter prediction procedure when decoding a picture thereafter.
- the plurality of transform kernels may include a separate transform kernel and a non-separate transform kernel.
- the plurality of transform kernels may include one non-separate transform kernel and M separate transform kernels.
- the value of the transform index information related to the one non-separate transform kernel is 0, the values of the transform index information related to the M separate transform kernels range from 1 to M, and M is a positive value greater than 1. can be an integer.
- the value of the transform index information associated with the one non-separate transform kernel is N
- the values of the transform index information associated with the M separate transform kernels are 0 to N-1 and N+1 to M
- M is a positive integer greater than 1
- N may be a positive integer smaller than M.
- the plurality of transform kernels may include L non-separate transform kernels and M separate transform kernels.
- the values of the transform index information related to the L non-separate transform kernels are 0 to L-1
- the values of the transform index information related to the M separate transform kernels are L to L+M-1
- L and M may be positive integers greater than 1.
- the image information may further include a flag indicating whether a non-separate transform kernel is applied to the primary transform.
- the transformation index information may be associated with a separation transformation kernel.
- the transform index information is the one non-separate transform kernel or the M It can be associated with any one of the separate transformation kernels.
- the transformation index information may be related to a separation transformation kernel.
- the plurality of transform kernels include L non-separate transform kernels and M separate transform kernels, and the value of the flag is 1, the transform index information may be related to the non-separate transform kernel.
- the flag may be context coded based on a context model.
- the context model may be determined based on the size of the current block, the shape of the current block, an intra prediction mode applied to the current block, and information on previously coded blocks.
- the transform index information may be binarized based on a fixed length coding (FLC) or a truncated binary code (TBC).
- FLC fixed length coding
- TBC truncated binary code
- the transform index information may be coded based on context coding or bypass coding.
- the transformation index information may be binarized based on a truncated unary code.
- the transform index information may be coded based on context coding or bypass coding.
- the transformation index information may be limited to be associated with a separate transformation kernel.
- the transformation index information may be associated with a separate transformation kernel.
- the image information may further include category information related to a category to which a transform kernel applied to the primary transform belongs among a plurality of categories into which the plurality of transform kernels are classified. .
- the category information may be transmitted at a higher level, and the conversion index information may be transmitted at a lower level.
- the upper level may be one of a sequence parameter set (SPS), a picture parameter set (PPS), a video parameter set (VPS), a picture header (PH), and a slice header (SH).
- the lower level may be one of a coding tree unit (CTU), a coding unit (CU), and a transform unit (TU).
- the above-described method according to the embodiments of this document may be implemented in the form of software, and the encoding device and/or decoding device according to this document may be used to display images of, for example, a TV, computer, smartphone, set-top box, display device, etc. It can be included in the device that performs the processing.
- a module can be stored in memory and executed by a processor.
- the memory may be internal or external to the processor, and may be coupled with the processor in a variety of well-known means.
- a processor may include an application-specific integrated circuit (ASIC), other chipsets, logic circuits, and/or data processing devices.
- 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 this document may be implemented and performed on a processor, microprocessor, controller, or chip. For example, functional units shown in each drawing may be implemented and performed on a computer, processor, microprocessor, controller, or chip. In this case, information for implementation (eg, information on instructions) or an algorithm may be stored in a digital storage medium.
- a decoding device and an encoding device to which the embodiment (s) of this document are applied are multimedia broadcasting transceiving devices, mobile communication terminals, home cinema video devices, digital cinema video devices, surveillance cameras, video conversation devices, video communication devices, and the like.
- OTT over the top video
- video devices may include game consoles, Blu-ray players, Internet-connected TVs, home theater systems, smart phones, tablet PCs, digital video recorders (DVRs), and the like.
- the processing method to which the embodiment(s) of this document is applied may be produced in the form of a program executed by a computer and stored in a computer-readable recording medium.
- Multimedia data having a data structure according to the embodiment(s) of this document may also be stored in a computer-readable recording medium.
- the computer-readable recording medium includes all types 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 A data storage device may be included.
- the computer-readable recording medium includes media implemented in the form of a carrier wave (eg, transmission through 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.
- embodiment(s) of this document may be implemented as a computer program product using program codes, and the program code may be executed on a computer by the embodiment(s) of this document.
- the program code may be stored on a carrier readable by a computer.
- FIG. 13 shows an example of a content streaming system to which the embodiments disclosed in this document can be applied.
- a content streaming system to which embodiments of this document are 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 compresses content input from multimedia input devices such as smart phones, cameras, camcorders, etc. into digital data to generate a bitstream and transmits it to the streaming server.
- multimedia input devices such as smart phones, cameras, and camcorders directly generate bitstreams
- the encoding server may be omitted.
- the bitstream may be generated by an encoding method or a bitstream generation method to which the embodiments of this document are applied, and the streaming server may temporarily store the bitstream in a 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 a medium informing a user of what kind of service is available.
- the web server transmits the request to the streaming server, and the streaming server transmits multimedia data to the user.
- the content streaming system may include a separate control server, and in this 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 can be received in real time. In this case, in order to provide smooth streaming service, the streaming server may store the bitstream for a certain period of time.
- Examples of the user devices include mobile phones, smart phones, laptop computers, digital broadcasting terminals, personal digital assistants (PDAs), portable multimedia players (PMPs), navigation devices, slate PCs, Tablet PC, ultrabook, wearable device (e.g., smartwatch, smart glass, HMD (head mounted display)), digital TV, desktop There may be computers, digital signage, and the like.
- PDAs personal digital assistants
- PMPs portable multimedia players
- navigation devices slate PCs
- Tablet PC ultrabook
- wearable device e.g., smartwatch, smart glass, HMD (head mounted display)
- digital TV desktop There may be computers, digital signage, and the like.
- Each server in the content streaming system may be operated as a distributed server, and in this case, data received from each server may be distributed and processed.
Landscapes
- Engineering & Computer Science (AREA)
- Multimedia (AREA)
- Signal Processing (AREA)
- Compression Or Coding Systems Of Tv Signals (AREA)
Abstract
Description
Claims (20)
- 디코딩 장치에 의하여 수행되는 영상 디코딩 방법에 있어서,비트스트림을 통하여 영상 정보를 획득하되, 상기 영상 정보는 레지듀얼 정보 및 변환 인덱스 정보를 포함하는 단계;상기 레지듀얼 정보를 기반으로 현재 블록에 대한 변환 계수들을 도출하는 단계;상기 변환 계수들을 기반으로 복수의 변환 커널들 중 상기 변환 인덱스 정보와 관련된 변환 커널을 사용하여 1차 변환을 수행함으로써, 상기 현재 블록에 대한 레지듀얼 샘플들을 도출하는 단계; 및상기 레지듀얼 샘플들을 기반으로 상기 현재 블록에 대한 복원 샘플들을 생성하는 단계를 포함하되,상기 복수의 변환 커널들은 분리 변환 커널과 비분리 변환 커널을 포함하는 것을 특징으로 하는, 영상 디코딩 방법.
- 제1항에 있어서,상기 복수의 변환 커널들이 1개의 비분리 변환 커널과 M개의 분리 변환 커널들을 포함하는 것을 기반으로, 상기 1개의 비분리 변환 커널과 관련된 변환 인덱스 정보의 값은 0이고, 상기 M개의 분리 변환 커널들과 관련된 변환 인덱스 정보의 값들은 1부터 M이며,M은 1보다 큰 양의 정수인 것을 특징으로 하는, 영상 디코딩 방법.
- 제1항에 있어서,상기 복수의 변환 커널들이 1개의 비분리 변환 커널과 M개의 분리 변환 커널들을 포함하는 것을 기반으로, 상기 1개의 비분리 변환 커널과 관련된 변환 인덱스 정보의 값은 N이고, 상기 M개의 분리 변환 커널들과 관련된 변환 인덱스 정보의 값들은 0부터 N-1 및 N+1부터 M이며,M은 1보다 큰 양의 정수이고, N은 M보다 작은 양의 정수인 것을 특징으로 하는, 영상 디코딩 방법.
- 제1항에 있어서,상기 복수의 변환 커널들이 L개의 비분리 변환 커널들과 M개의 분리 변환 커널들을 포함하는 것을 기반으로, 상기 L개의 비분리 변환 커널들과 관련된 변환 인덱스 정보의 값들은 0부터 L-1이고, 상기 M개의 분리 변환 커널들과 관련된 변환 인덱스 정보의 값들은 L부터 L+M-1이며,L 및 M은 1보다 큰 양의 정수인 것을 특징으로 하는, 영상 디코딩 방법.
- 제1항에 있어서,상기 영상 정보는 상기 1차 변환에 비분리 변환 커널이 적용되는지 여부를 나타내는 플래그를 더 포함하고,상기 플래그의 값이 0인 것을 기반으로 상기 변환 인덱스 정보는 분리 변환 커널과 관련되는 것을 특징으로 하는, 영상 디코딩 방법
- 제5항에 있어서,상기 복수의 변환 커널들이 L개의 비분리 변환 커널들과 M개의 분리 변환 커널들을 포함하고, 상기 플래그의 값이 1인 것을 기반으로, 상기 변환 인덱스 정보는 비분리 변환 커널과 관련되고, L 및 M은 1보다 큰 양의 정수인 것을 특징으로 하는, 영상 디코딩 방법.
- 제5항에 있어서,상기 플래그는 컨텍스트 모델(Context model)을 기반으로 컨텍스트 코딩(Context coding)될 수 있고,상기 컨텍스트 모델은 상기 현재 블록의 크기, 상기 현재 블록의 모양, 상기 현재 블록에 적용되는 인트라 예측 모드 및 이전에 코딩된 블록들의 정보를 기반으로 결정되는 것을 특징으로 하는, 영상 디코딩 방법.
- 제1항에 있어서,상기 변환 인덱스 정보는 고정 길이 코드(Fixed Length Coding, FLC) 또는 트런케이티드 이항 코드(Truncated binary code, TBC)를 기반으로 이진화될 수 있고,상기 변환 인덱스 정보는 컨텍스트 코딩(Context coding) 또는 바이패스 코딩(Bypass coding)을 기반으로 코딩되는 것을 특징으로 하는, 영상 디코딩 방법.
- 제1항에 있어서,상기 변환 인덱스 정보는 트런케이티드 단항 코드(Truncated Unary code)를 기반으로 이진화될 수 있고,상기 변환 인덱스 정보는 컨텍스트 코딩(Context coding) 또는 바이패스 코딩(Bypass coding)을 기반으로 코딩되는 것을 특징으로 하는, 영상 디코딩 방법.
- 제1항에 있어서,상기 현재 블록에 대한 레지듀얼 샘플들을 도출하는 단계는상기 변환 계수들에 대해 비분리 변환인 2차 변환을 수행함으로써, 상기 현재 블록에 대한 수정된 변환 계수들을 도출하는 단계; 및상기 수정된 변환 계수들에 대해 상기 변환 인덱스 정보와 관련된 변환 커널을 사용하여 상기 1차 변환을 수행함으로써, 상기 현재 블록에 대한 레지듀얼 샘플들을 도출하는 단계를 포함하고,상기 2차 변환이 수행되는 것을 기반으로, 상기 변환 인덱스 정보는 분리 변환 커널과 관련되도록 제한되는 것을 특징으로 하는, 영상 디코딩 방법.
- 제10항에 있어서,상기 현재 블록의 가로 및 세로가 미리 정해진 크기를 초과하고, 상기 2차 변환이 수행되는 것을 기반으로, 상기 변환 인덱스 정보는 분리 변환 커널과 관련되도록 제한되는 것을 특징으로 하는, 영상 디코딩 방법.
- 제1항에 있어서,상기 영상 정보는 상기 복수의 변환 커널들이 분류된 복수의 카테고리들 중 상기 1차 변환에 적용되는 변환 커널이 속하는 카테고리와 관련된 카테고리 정보를 더 포함하는 것을 특징으로 하는, 영상 디코딩 방법.
- 제12항에 있어서,상기 카테고리 정보는 상위 레벨(level)에서 전송되고, 상기 변환 인덱스 정보는 하위 레벨에서 전송되며,상기 상위 레벨은 SPS(Sequence parameter set), PPS(Picture parameter set), VPS(Video parameter set), PH(Picture header), SH(Slice header) 중 하나이고, 상기 하위 레벨은 CTU(Coding tree unit), CU(Coding unit), TU(Transform unit) 중 하나인 것을 특징으로 하는, 영상 디코딩 방법.
- 인코딩 장치에 의하여 수행되는 영상 인코딩 방법에 있어서,현재 블록에 대한 레지듀얼 샘플들을 도출하는 단계;상기 레지듀얼 샘플들에 대해 변환 커널을 기반으로 1차 변환을 수행함으로써, 상기 현재 블록에 대한 변환 계수들을 도출하는 단계;복수의 변환 커널들 중 상기 변환 커널과 관련된 변환 인덱스 정보를 생성하는 단계;상기 변환 계수들을 기반으로 레지듀얼 정보를 생성하는 단계; 및상기 변환 인덱스 정보 및 상기 레지듀얼 정보를 포함하는 영상 정보를 인코딩하는 단계를 포함하되,상기 복수의 변환 커널들은 분리 변환 커널과 비분리 변환 커널을 포함하는 것을 특징으로 하는, 영상 인코딩 방법.
- 제14항에 있어서,상기 복수의 변환 커널들이 1개의 비분리 변환 커널과 M개의 분리 변환 커널들을 포함하는 것을 기반으로, 상기 1개의 비분리 변환 커널과 관련된 변환 인덱스 정보의 값은 0이고, 상기 M개의 분리 변환 커널들과 관련된 변환 인덱스 정보의 값들은 1부터 M이며,M은 1보다 큰 양의 정수인 것을 특징으로 하는, 영상 인코딩 방법.
- 제14항에 있어서,상기 복수의 변환 커널들이 1개의 비분리 변환 커널과 M개의 분리 변환 커널들을 포함하는 것을 기반으로, 상기 1개의 비분리 변환 커널과 관련된 변환 인덱스 정보의 값은 N이고, 상기 M개의 분리 변환 커널들과 관련된 변환 인덱스 정보의 값들은 0부터 N-1 및 N+1부터 M이며,M은 1보다 큰 양의 정수이고, N은 M보다 작은 양의 정수인 것을 특징으로 하는, 영상 인코딩 방법.
- 제14항에 있어서,상기 복수의 변환 커널들이 L개의 비분리 변환 커널들과 M개의 분리 변환 커널들을 포함하는 것을 기반으로, 상기 L개의 비분리 변환 커널들과 관련된 변환 인덱스 정보의 값들은 0부터 L-1이고, 상기 M개의 분리 변환 커널들과 관련된 변환 인덱스 정보의 값들은 L부터 L+M-1이며,L 및 M은 1보다 큰 양의 정수인 것을 특징으로 하는, 영상 인코딩 방법.
- 제14항에 있어서,상기 변환 인덱스 정보가 분리 변환 커널과 관련되는 것을 기반으로, 상기 레지듀얼 정보를 생성하는 단계는상기 변환 계수들에 대해 비분리 변환인 2차 변환을 수행함으로써, 상기 현재 블록에 대한 수정된 변환 계수들을 도출하는 단계; 및상기 수정된 변환 계수들을 기반으로 레지듀얼 정보를 생성하는 단계를 포함하고,상기 변환 인덱스 정보가 비분리 변환 커널과 관련되는 것을 기반으로, 상기 2차 변환은 수행되지 않도록 제한되는 것을 특징으로 하는, 영상 인코딩 방법.
- 제14항의 영상 인코딩 방법에 의해 생성된 비트스트림을 저장하는 컴퓨터 판독 가능한 디지털 저장 매체.
- 영상에 대한 데이터의 전송 방법에 있어서,상기 영상에 대한 비트스트림을 획득하되, 상기 비트스트림은 현재 블록에 대한 레지듀얼 샘플들을 도출하는 단계, 상기 레지듀얼 샘플들에 대해 변환 커널을 기반으로 1차 변환을 수행함으로써, 상기 현재 블록에 대한 변환 계수들을 도출하는 단계, 복수의 변환 커널들 중 상기 변환 커널과 관련된 변환 인덱스 정보를 생성하는 단계, 상기 변환 계수들을 기반으로 레지듀얼 정보를 생성하는 단계 및 상기 변환 인덱스 정보 및 상기 레지듀얼 정보를 포함하는 영상 정보를 인코딩하는 단계를 기반으로 생성되는 단계; 및상기 비트스트림을 포함하는 상기 데이터를 전송하는 단계를 포함하고,상기 복수의 변환 커널들은 분리 변환 커널과 비분리 변환 커널을 포함하는 것을 특징으로 하는, 전송 방법.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US202163270573P | 2021-10-22 | 2021-10-22 | |
US63/270,573 | 2021-10-22 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2023068840A1 true WO2023068840A1 (ko) | 2023-04-27 |
Family
ID=86059522
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/KR2022/016033 WO2023068840A1 (ko) | 2021-10-22 | 2022-10-20 | 비분리 1차 변환 설계 방법 및 장치 |
Country Status (1)
Country | Link |
---|---|
WO (1) | WO2023068840A1 (ko) |
Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20180103252A1 (en) * | 2016-10-12 | 2018-04-12 | Qualcomm Incorporated | Primary transform and secondary transform in video coding |
KR20200086734A (ko) * | 2018-09-02 | 2020-07-17 | 엘지전자 주식회사 | 비디오 신호의 부호화/복호화 방법 및 이를 위한 장치 |
WO2020213946A1 (ko) * | 2019-04-16 | 2020-10-22 | 엘지전자 주식회사 | 변환 인덱스를 이용하는 영상 코딩 |
WO2021136821A1 (en) * | 2019-12-30 | 2021-07-08 | Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. | Encoding and decoding of color components in pictures |
-
2022
- 2022-10-20 WO PCT/KR2022/016033 patent/WO2023068840A1/ko active Application Filing
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20180103252A1 (en) * | 2016-10-12 | 2018-04-12 | Qualcomm Incorporated | Primary transform and secondary transform in video coding |
KR20200086734A (ko) * | 2018-09-02 | 2020-07-17 | 엘지전자 주식회사 | 비디오 신호의 부호화/복호화 방법 및 이를 위한 장치 |
WO2020213946A1 (ko) * | 2019-04-16 | 2020-10-22 | 엘지전자 주식회사 | 변환 인덱스를 이용하는 영상 코딩 |
WO2021136821A1 (en) * | 2019-12-30 | 2021-07-08 | Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. | Encoding and decoding of color components in pictures |
Non-Patent Citations (1)
Title |
---|
B. RAY (QUALCOMM), L. KEROFSKY (QUALCOMM), M. COBAN (QUALCOMM), M. KARCZEWICZ, H. EGILMEZ, V. SEREGIN (QUALCOMM): "Enhanced Intra MTS and LFNST for compression beyond VVC", 22. JVET MEETING; 20210420 - 20210428; TELECONFERENCE; (THE JOINT VIDEO EXPLORATION TEAM OF ISO/IEC JTC1/SC29/WG11 AND ITU-T SG.16 ), no. JVET-V0116 ; m56530, 23 April 2021 (2021-04-23), XP030294293 * |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
WO2020009556A1 (ko) | 변환에 기반한 영상 코딩 방법 및 그 장치 | |
WO2020046091A1 (ko) | 다중 변환 선택에 기반한 영상 코딩 방법 및 그 장치 | |
WO2020213944A1 (ko) | 영상 코딩에서 매트릭스 기반의 인트라 예측을 위한 변환 | |
WO2020213946A1 (ko) | 변환 인덱스를 이용하는 영상 코딩 | |
WO2020231140A1 (ko) | 적응적 루프 필터 기반 비디오 또는 영상 코딩 | |
WO2020213945A1 (ko) | 인트라 예측 기반 영상 코딩에서의 변환 | |
WO2020116961A1 (ko) | 이차 변환에 기반한 영상 코딩 방법 및 그 장치 | |
WO2021096172A1 (ko) | 변환에 기반한 영상 코딩 방법 및 그 장치 | |
WO2020130661A1 (ko) | 이차 변환에 기반한 영상 코딩 방법 및 그 장치 | |
WO2021040492A1 (ko) | 비디오/영상 코딩 시스템에서 변환 계수 코딩 방법 및 장치 | |
WO2020167097A1 (ko) | 영상 코딩 시스템에서 인터 예측을 위한 인터 예측 타입 도출 | |
WO2021040319A1 (ko) | 비디오/영상 코딩 시스템에서 라이스 파라미터 도출 방법 및 장치 | |
WO2021040398A1 (ko) | 팔레트 이스케이프 코딩 기반 영상 또는 비디오 코딩 | |
WO2020197274A1 (ko) | 변환에 기반한 영상 코딩 방법 및 그 장치 | |
WO2021066618A1 (ko) | 변환 스킵 및 팔레트 코딩 관련 정보의 시그널링 기반 영상 또는 비디오 코딩 | |
WO2021040487A1 (ko) | 영상 코딩 시스템에서 레지듀얼 데이터 코딩에 대한 영상 디코딩 방법 및 그 장치 | |
WO2020256482A1 (ko) | 변환에 기반한 영상 코딩 방법 및 그 장치 | |
WO2021006700A1 (ko) | 영상 코딩 시스템에서 레지듀얼 코딩 방법에 대한 플래그를 사용하는 영상 디코딩 방법 및 그 장치 | |
WO2020130581A1 (ko) | 이차 변환에 기반한 영상 코딩 방법 및 그 장치 | |
WO2021158048A1 (ko) | Tsrc 가용 플래그의 시그널링 관련 영상 디코딩 방법 및 그 장치 | |
WO2021040407A1 (ko) | 영상 코딩 시스템에서 단순화된 레지듀얼 데이터 코딩을 사용하는 영상 디코딩 방법 및 그 장치 | |
WO2021025526A1 (ko) | 변환에 기반한 영상 코딩 방법 및 그 장치 | |
WO2020149594A1 (ko) | 영상 코딩 시스템에서 고주파 제로잉을 기반으로 레지듀얼 정보를 코딩하는 영상 디코딩 방법 및 그 장치 | |
WO2021034100A1 (ko) | 영상 코딩 시스템에서 무손실 코딩을 적용하는 영상 디코딩 방법 및 그 장치 | |
WO2020185005A1 (ko) | 변환에 기반한 영상 코딩 방법 및 그 장치 |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
121 | Ep: the epo has been informed by wipo that ep was designated in this application |
Ref document number: 22884062 Country of ref document: EP Kind code of ref document: A1 |
|
REG | Reference to national code |
Ref country code: BR Ref legal event code: B01A Ref document number: 112024007709 Country of ref document: BR |
|
WWE | Wipo information: entry into national phase |
Ref document number: 2022884062 Country of ref document: EP |
|
ENP | Entry into the national phase |
Ref document number: 2022884062 Country of ref document: EP Effective date: 20240522 |