WO2019117636A1 - 비분리 2차 변환에 기반한 영상 코딩 방법 및 그 장치 - Google Patents
비분리 2차 변환에 기반한 영상 코딩 방법 및 그 장치 Download PDFInfo
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Definitions
- the present invention relates to an image coding technique, and more particularly, to an image decoding method and apparatus according to a non-separating quadratic transformation in an image coding system.
- HD high definition
- UHD ultra high definition
- the present invention provides a method and apparatus for enhancing video coding efficiency.
- an image decoding method and apparatus for determining whether an NSST index is coded based on transform coefficients of a target block.
- an image decoding method performed by a decoding apparatus includes deriving transform coefficients of a target block from a bitstream, deriving a Non-Separable Secondary Transform (NSST) index for the target block, transforming the transform coefficients of the target block based on the NSST index Performing inversed transform on the residual samples to derive residual samples of the target block, and generating a reconstructed picture based on the residual samples.
- NSST Non-Separable Secondary Transform
- a decoding apparatus for performing image decoding.
- the decoding apparatus includes an entropy decoding unit for deriving transform coefficients of a target block from a bitstream and deriving a Non-Separable Secondary Transform (NSST) index for the target block, a transformation unit for transforming the transform coefficient And an adder for generating a reconstructed picture on the basis of the residual samples.
- the inverse transformer performs an inversed transform on the residual samples to derive residual samples of the target block.
- a video encoding method performed by an encoding apparatus.
- the method includes deriving residual samples of a target block, deriving transform coefficients of the target block by performing transform on the residual samples, determining whether to encode the NSST index for the target block, And encoding the information on the transform coefficients, wherein the step of determining whether to encode the NSST index comprises the steps of: R + 1-th to N-th transforms of the transform coefficients of the target block, And determining that the NSST index is not to be encoded if the non-zero transform coefficient is included in the (N + 1) th transform coefficients from the (R + 1) -th transform coefficient, Wherein R is a reduced coefficient, and R is smaller than N.
- a video encoding apparatus includes an adder for deriving residual samples of a target block, a transform unit for transforming the residual samples to derive transform coefficients of the target block, and a transform unit for transforming the NSST index
- the entropy encoding unit scans R + 1-th to N-th transform coefficients of the transform coefficients of the target block, and outputs the transform coefficients to the entropy encoding unit, And determines that the NSST index is not encoded when the non-zero transform coefficient is included in the (R + 1) th to Nth transform coefficients, wherein N is the number of samples of the upper left target region of the target block, R is a reduced coefficient, and R is smaller than N.
- the range of the NSST index can be derived based on the specific condition of the target block, thereby reducing the bit amount for the NSST index and improving the overall coding efficiency.
- the transmission of a syntax element for the NSST index can be determined based on the transform coefficients for the target block, thereby reducing the bit amount for the NSST index and improving the overall coding efficiency .
- FIG. 1 is a view for schematically explaining a configuration of a video encoding apparatus to which the present invention can be applied.
- FIG. 2 shows an example of an image encoding method performed by the video encoding apparatus.
- FIG. 3 is a view for schematically explaining a configuration of a video decoding apparatus to which the present invention can be applied.
- FIG. 4 shows an example of an image decoding method performed by a decoding apparatus.
- FIG. 6 exemplarily shows intra-directional modes of 65 prediction directions.
- FIGS. 7A and 7B are flowcharts illustrating a coding process of a transform coefficient according to an embodiment.
- FIG. 8 is a diagram for explaining the arrangement of transform coefficients based on a target block according to an embodiment of the present invention.
- FIG. 9 shows an example of scanning R + 1 to N conversion coefficients.
- 10A and 10B are flowcharts illustrating a coding process of an NSST index according to an embodiment.
- FIG. 11 shows an example of determining whether the NSST index is coded.
- FIG. 13 schematically shows an image encoding method by the encoding apparatus according to the present invention.
- FIG. 14 schematically shows an encoding apparatus for performing a video encoding method according to the present invention.
- FIG. 15 schematically shows a video decoding method by a decoding apparatus according to the present invention.
- FIG. 16 schematically shows a decoding apparatus for performing an image decoding method according to the present invention.
- the present invention relates to video / video coding.
- the method / embodiment disclosed herein may be applied to a method disclosed in the versatile video coding (VVC) standard or the next generation video / image coding standard.
- VVC versatile video coding
- a picture generally refers to a unit that represents one image in a specific time zone
- a slice is a unit that constitutes a part of a picture in coding.
- One picture may be composed of a plurality of slices, and pictures and slices may be used in combination if necessary.
- a pixel or a pel may mean a minimum unit of a picture (or image). Also, a 'sample' may be used as a term corresponding to a pixel.
- a sample may generally represent a pixel or pixel value and may only represent a pixel / pixel value of a luma component or only a pixel / pixel value of a chroma component.
- a unit represents a basic unit of image processing.
- a unit may include at least one of a specific area of a picture and information related to the area.
- the unit may be used in combination with terms such as a block or an area in some cases.
- an MxN block may represent a set of samples or transform coefficients consisting of M columns and N rows.
- FIG. 1 is a view for schematically explaining a configuration of a video encoding apparatus to which the present invention can be applied.
- the video encoding apparatus 100 includes a picture dividing unit 105, a predicting unit 110, a residual processing unit 120, an entropy encoding unit 130, an adding unit 140, a filter unit 150 And a memory 160.
- the residual processing unit 120 may include a subtracting unit 121, a transforming unit 122, a quantizing unit 123, a reordering unit 124, an inverse quantizing unit 125 and an inverse transforming unit 126.
- the picture dividing unit 105 may divide the inputted picture into at least one processing unit.
- the processing unit may be referred to as a coding unit (CU).
- the coding unit may be recursively partitioned according to a quad-tree binary-tree (QTBT) structure from the largest coding unit (LCU).
- QTBT quad-tree binary-tree
- LCU largest coding unit
- one coding unit may be divided into a plurality of coding units of deeper depth based on a quadtree structure and / or a binary tree structure.
- the quadtree structure is applied first and the binary tree structure can be applied later.
- a binary tree structure may be applied first.
- the coding procedure according to the present invention can be performed based on the final coding unit which is not further divided.
- the maximum coding unit may be directly used as the final coding unit based on the coding efficiency or the like depending on the image characteristics, or the coding unit may be recursively divided into lower-depth coding units Lt; / RTI > may be used as the final coding unit.
- the coding procedure may include a procedure such as prediction, conversion, and restoration, which will be described later.
- the processing unit may include a coding unit (CU) prediction unit (PU) or a transform unit (TU).
- the coding unit may be split from the largest coding unit (LCU) into coding units of deeper depth along the quad tree structure.
- LCU largest coding unit
- the maximum coding unit may be directly used as the final coding unit based on the coding efficiency or the like depending on the image characteristics, or the coding unit may be recursively divided into lower-depth coding units Lt; / RTI > may be used as the final coding unit.
- SCU smallest coding unit
- the coding unit can not be divided into smaller coding units than the minimum coding unit.
- the term " final coding unit " means a coding unit on which the prediction unit or the conversion unit is partitioned or divided.
- a prediction unit is a unit that is partitioned from a coding unit, and may be a unit of sample prediction. At this time, the prediction unit may be divided into sub-blocks.
- the conversion unit may be divided along the quad-tree structure from the coding unit, and may be a unit for deriving a conversion coefficient and / or a unit for deriving a residual signal from the conversion factor.
- the coding unit may be referred to as a coding block (CB)
- the prediction unit may be referred to as a prediction block (PB)
- the conversion unit may be referred to as a transform block (TB).
- the prediction block or prediction unit may refer to a specific area in the form of a block in a picture and may include an array of prediction samples.
- a transform block or transform unit may refer to a specific region in the form of a block within a picture, and may include an array of transform coefficients or residual samples.
- the prediction unit 110 may perform a prediction on a current block to be processed (hereinafter, referred to as a current block), and may generate a predicted block including prediction samples for the current block.
- the unit of prediction performed in the prediction unit 110 may be a coding block, a transform block, or a prediction block.
- the prediction unit 110 may determine whether intra prediction or inter prediction is applied to the current block. For example, the prediction unit 110 may determine whether intra prediction or inter prediction is applied in units of CU.
- the prediction unit 110 may derive a prediction sample for a current block based on a reference sample outside the current block in a picture to which the current block belongs (hereinafter referred to as a current picture). At this time, the prediction unit 110 may derive a prediction sample based on (i) an average or interpolation of neighboring reference samples of the current block, (ii) The prediction sample may be derived based on a reference sample existing in a specific (prediction) direction with respect to the prediction sample among the samples. (i) may be referred to as a non-directional mode or a non-angle mode, and (ii) may be referred to as a directional mode or an angular mode.
- the prediction mode may have, for example, 33 directional prediction modes and at least two non-directional modes.
- the non-directional mode may include a DC prediction mode and a planar mode (Planar mode).
- the prediction unit 110 may determine a prediction mode applied to a current block using a prediction mode applied to a neighboring block.
- the prediction unit 110 may derive a prediction sample for a current block based on a sample specified by a motion vector on a reference picture.
- the prediction unit 110 may derive a prediction sample for a current block by applying one of a skip mode, a merge mode, and a motion vector prediction (MVP) mode.
- the prediction unit 110 can use motion information of a neighboring block as motion information of a current block.
- difference residual between the predicted sample and the original sample is not transmitted unlike the merge mode.
- MVP mode a motion vector of a current block can be derived by using a motion vector of a neighboring block as a motion vector predictor to use as a motion vector predictor of a current block.
- a neighboring block may include a spatial neighboring block existing in a current picture and a temporal neighboring block existing in a reference picture.
- the reference picture including the temporal neighboring block may be referred to as a collocated picture (colPic).
- the motion information may include a motion vector and a reference picture index.
- Information such as prediction mode information and motion information may be (entropy) encoded and output in the form of a bit stream.
- the highest picture on the reference picture list may be used as a reference picture.
- the reference pictures included in the picture order count can be sorted on the basis of the picture order count (POC) difference between the current picture and the corresponding reference picture.
- POC picture order count
- the POC corresponds to the display order of the pictures and can be distinguished from the coding order.
- the subtraction unit 121 generates residual samples that are the difference between the original sample and the predicted sample. When the skip mode is applied, a residual sample may not be generated as described above.
- the transforming unit 122 transforms the residual samples on a transform block basis to generate a transform coefficient.
- the transforming unit 122 can perform the transform according to the size of the transform block and a prediction mode applied to the coding block or the prediction block spatially overlapping the transform block. For example, if intraprediction is applied to the coding block or the prediction block that overlaps the transform block and the transform block is a 4 ⁇ 4 residue array, the residual sample is transformed into a discrete sine transform (DST) In other cases, the residual samples can be converted using a DCT (Discrete Cosine Transform) conversion kernel.
- DST discrete sine transform
- the quantization unit 123 may quantize the transform coefficients to generate quantized transform coefficients.
- the reordering unit 124 rearranges the quantized transform coefficients.
- the reordering unit 124 may rearrange the block-shaped quantized transform coefficients into a one-dimensional vector form through a scanning method of coefficients.
- the reordering unit 124 may be a part of the quantization unit 123, although the reordering unit 124 is described as an alternative configuration.
- the entropy encoding unit 130 may perform entropy encoding on the quantized transform coefficients.
- Entropy encoding may include, for example, an encoding method such as exponential Golomb, context-adaptive variable length coding (CAVLC), context-adaptive binary arithmetic coding (CABAC)
- CAVLC context-adaptive variable length coding
- CABAC context-adaptive binary arithmetic coding
- the entropy encoding unit 130 may encode the information necessary for video restoration (such as the value of a syntax element) together with the quantized transform coefficient or separately.
- the entropy encoded information may be transmitted or stored in units of NAL (network abstraction layer) units in the form of a bit stream.
- NAL network abstraction layer
- the inverse quantization unit 125 inversely quantizes the quantized values (quantized transform coefficients) in the quantization unit 123 and the inverse transformation unit 126 inversely quantizes the inversely quantized values in the inverse quantization unit 125, .
- the adder 140 combines the residual sample and the predicted sample to reconstruct the picture.
- the residual samples and the prediction samples are added in units of blocks so that a reconstruction block can be generated.
- the adding unit 140 may be a part of the predicting unit 110, Meanwhile, the addition unit 140 may be referred to as a restoration unit or a restoration block generation unit.
- the filter unit 150 may apply a deblocking filter and / or a sample adaptive offset. Through deblocking filtering and / or sample adaptive offsets, artifacts in the block boundary in the reconstructed picture or distortion in the quantization process can be corrected.
- the sample adaptive offset can be applied on a sample-by-sample basis and can be applied after the process of deblocking filtering is complete.
- the filter unit 150 may apply an ALF (Adaptive Loop Filter) to the restored picture.
- the ALF may be applied to the reconstructed picture after the deblocking filter and / or sample adaptive offset is applied.
- the memory 160 may store restored pictures (decoded pictures) or information necessary for encoding / decoding.
- the reconstructed picture may be a reconstructed picture whose filtering procedure has been completed by the filter unit 150.
- the stored restored picture may be used as a reference picture for (inter) prediction of another picture.
- the memory 160 may store (reference) pictures used for inter prediction. At this time, the pictures used for inter prediction can be designated by a reference picture set or a reference picture list.
- the image encoding method may include intra / inter prediction, transform, quantization, and entropy encoding.
- a prediction block of the current block can be generated through intra / inter prediction, and a residual block of the current block can be generated through subtraction between the input block of the current block and the prediction block.
- the coefficients for the current block may be generated by transforming the residual block, that is, the coefficent block.
- the transform coefficients may be quantized and entropy encoded and stored in a bitstream.
- FIG. 3 is a view for schematically explaining a configuration of a video decoding apparatus to which the present invention can be applied.
- the video decoding apparatus 300 includes an entropy decoding unit 310, a residual processing unit 320, a predicting unit 330, an adding unit 340, a filter unit 350, and a memory 360 .
- the residual processing unit 320 may include a rearrangement unit 321, an inverse quantization unit 322, and an inverse transformation unit 323.
- the video decoding apparatus 300 can restore video in response to a process in which video information is processed in the video encoding apparatus.
- the video decoding apparatus 300 may perform video decoding using a processing unit applied in the video encoding apparatus.
- the processing unit block of video decoding may be, for example, a coding unit and, in another example, a coding unit, a prediction unit or a conversion unit.
- the coding unit may be partitioned along the quad tree structure and / or the binary tree structure from the maximum coding unit.
- a prediction unit and a conversion unit may be further used as the case may be, in which case the prediction block is a block derived or partitioned from the coding unit and may be a unit of sample prediction. At this time, the prediction unit may be divided into sub-blocks.
- the conversion unit may be divided along the quad tree structure from the coding unit and may be a unit that derives the conversion factor or a unit that derives the residual signal from the conversion factor.
- the entropy decoding unit 310 may parse the bitstream and output information necessary for video restoration or picture restoration. For example, the entropy decoding unit 310 decodes information in the bitstream based on a coding method such as exponential Golomb coding, CAVLC, or CABAC, and calculates a value of a syntax element necessary for video restoration, a quantized value Lt; / RTI >
- a coding method such as exponential Golomb coding, CAVLC, or CABAC
- the CABAC entropy decoding method includes receiving a bean corresponding to each syntax element in a bitstream, decoding decoding target information of the decoding target syntax element, decoding information of a surrounding and decoding target block, or information of a symbol / A context model is determined and an occurrence probability of a bin is predicted according to the determined context model to perform arithmetic decoding of the bean to generate a symbol corresponding to the value of each syntax element have.
- the CABAC entropy decoding method can update the context model using the information of the decoded symbol / bin for the context model of the next symbol / bean after determining the context model.
- Information regarding prediction in the information decoded by the entropy decoding unit 310 is provided to the predicting unit 330.
- the residual value in which the entropy decoding is performed in the entropy decoding unit 310 that is, the quantized transform coefficient, 321).
- the reordering unit 321 may rearrange the quantized transform coefficients into a two-dimensional block form.
- the reordering unit 321 can perform reordering in response to the coefficient scanning performed in the encoding apparatus.
- the rearrangement unit 321 may be a part of the dequantization unit 322, although the rearrangement unit 321 has been described as a separate structure.
- the inverse quantization unit 322 can dequantize the quantized transform coefficients based on the (inverse) quantization parameter, and output the transform coefficients. At this time, the information for deriving the quantization parameter may be signaled from the encoding device.
- the inverse transform unit 323 may invert the transform coefficients to derive the residual samples.
- the prediction unit 330 may predict a current block and may generate a predicted block including prediction samples for the current block.
- the unit of prediction performed in the prediction unit 330 may be a coding block, a transform block, or a prediction block.
- the predicting unit 330 may determine whether intra prediction or inter prediction is to be applied based on the prediction information.
- a unit for determining whether to apply intra prediction or inter prediction may differ from a unit for generating a prediction sample.
- units for generating prediction samples in inter prediction and intra prediction may also be different.
- whether inter prediction or intra prediction is to be applied can be determined in units of CU.
- the prediction mode may be determined in units of PU to generate prediction samples.
- a prediction mode may be determined in units of PU, and prediction samples may be generated in units of TU.
- the prediction unit 330 may derive a prediction sample for the current block based on the neighbor reference samples in the current picture.
- the prediction unit 330 may derive a prediction sample for the current block by applying a directional mode or a non-directional mode based on the neighbor reference samples of the current block.
- a prediction mode to be applied to the current block may be determined using the intra prediction mode of the neighboring block.
- the prediction unit 330 may derive a prediction sample for a current block based on a sample specified on a reference picture by a motion vector on the reference picture.
- the predicting unit 330 may apply a skip mode, a merge mode, or an MVP mode to derive a prediction sample for a current block.
- motion information necessary for inter-prediction of a current block provided in the video encoding apparatus for example, information on a motion vector, a reference picture index, and the like may be acquired or derived based on the prediction information
- motion information of a neighboring block can be used as motion information of the current block.
- the neighboring block may include a spatial neighboring block and a temporal neighboring block.
- the predicting unit 330 may construct a merge candidate list using the motion information of the available neighboring blocks and use the information indicated by the merge index on the merge candidate list as the motion vector of the current block.
- the merge index may be signaled from the encoding device.
- the motion information may include a motion vector and a reference picture. When the motion information of temporal neighboring blocks is used in the skip mode and the merge mode, the highest picture on the reference picture list can be used as a reference picture.
- the difference between the predicted sample and the original sample is not transmitted.
- a motion vector of a current block can be derived using a motion vector of a neighboring block as a motion vector predictor.
- the neighboring block may include a spatial neighboring block and a temporal neighboring block.
- a merge candidate list may be generated using a motion vector of the reconstructed spatial neighboring block and / or a motion vector corresponding to a Col block that is a temporally neighboring block.
- the motion vector of the candidate block selected in the merge candidate list is used as the motion vector of the current block.
- the prediction information may include a merge index indicating a candidate block having an optimal motion vector selected from the candidate blocks included in the merge candidate list.
- the predicting unit 330 can derive the motion vector of the current block using the merge index.
- a motion vector predictor candidate list is generated by using a motion vector of the reconstructed spatial neighboring block and / or a motion vector corresponding to a Col block which is a temporally neighboring block . That is, the motion vector of the reconstructed spatial neighboring block and / or the motion vector corresponding to the neighboring block Col may be used as a motion vector candidate.
- the information on the prediction may include a predicted motion vector index indicating an optimal motion vector selected from the motion vector candidates included in the list.
- the predicting unit 330 may use the motion vector index to select a predictive motion vector of the current block from the motion vector candidates included in the motion vector candidate list.
- the predicting unit of the encoding apparatus can obtain the motion vector difference (MVD) between the motion vector of the current block and the motion vector predictor, and can output it as a bit stream. That is, MVD can be obtained by subtracting the motion vector predictor from the motion vector of the current block.
- the predicting unit 330 may obtain the motion vector difference included in the information on the prediction, and may derive the motion vector of the current block through addition of the motion vector difference and the motion vector predictor.
- the prediction unit may also acquire or derive a reference picture index or the like indicating the reference picture from the information on the prediction.
- the adder 340 may add a residual sample and a prediction sample to reconstruct a current block or a current picture.
- the adder 340 may add the residual samples and the prediction samples on a block-by-block basis to reconstruct the current picture.
- the addition unit 340 is described as an alternative configuration, but the addition unit 340 may be a part of the prediction unit 330.
- the addition unit 340 may be referred to as a restoration unit or a restoration block generation unit.
- the filter unit 350 may apply deblocking filtering sample adaptive offsets, and / or ALF, etc. to the reconstructed pictures.
- the sample adaptive offset may be applied on a sample-by-sample basis and may be applied after deblocking filtering.
- the ALF may be applied after deblocking filtering and / or sample adaptive offsets.
- the memory 360 may store a reconstructed picture (decoded picture) or information necessary for decoding.
- the reconstructed picture may be a reconstructed picture in which the filtering procedure has been completed by the filter unit 350.
- the memory 360 may store pictures used for inter prediction.
- the pictures used for inter prediction may be designated by a reference picture set or a reference picture list.
- the reconstructed picture can be used as a reference picture for another picture.
- the memory 360 may output the restored picture according to the output order.
- the image decoding method may include entropy decoding, inverse quantization, inverse transform, and intra / inter prediction.
- an inverse process of the encoding method may be performed.
- quantized transform coefficients can be obtained through entropy decoding on a bitstream, and a coefficient block, i.e., transform coefficients, of the current block can be obtained through an inverse quantization process on the quantized transform coefficients.
- a residual block of the current block can be derived through an inverse transformation on the transform coefficients, and a predictive block of the current block derived through intra / inter prediction is added to the residual block of the current block, A reconstructed block can be derived.
- the transform coefficients of the lower frequency for the residual block of the current block can be derived through the above-described transform, and a zero tail can be derived at the end of the residual block.
- the transformation may be composed of two main processes, which may include a core transform and a secondary transform.
- the transform comprising the core transform and the quadratic transform may be referred to as multiple transform techniques.
- the transform unit may correspond to the transform unit in the encoding apparatus of FIG. 1 described above, and the inverse transform unit may correspond to the inverse transform unit in the encoding apparatus of FIG. 1 or the inverse transform unit in the decoding apparatus of FIG. .
- the transforming unit may perform a primary transform based on the residual samples (residual sample array) in the residual block to derive (primary) transform coefficients (S510).
- the first order transformation may comprise Adaptive Multiple Core Transform (AMT).
- AMT Adaptive Multiple Core Transform
- MTS Multiple Transform Set
- the adaptive multi-core transformation may represent a method of additionally using DCT (Discrete Cosine Transform) type 2, DST (Discrete Sine Transform) type 7, DCT type 8, and / or DST type 1. That is, the adaptive multi-core transform is a method of transforming a spatial domain residual signal (or a residual block) based on a plurality of transformation kernels selected from the DCT type 2, the DST type 7, the DCT type 8, and the DST type 1 (Or first order transform coefficients) in the frequency domain.
- the primary transform coefficients may be referred to as temporary transform coefficients in the transform unit.
- a transform from a spatial domain to a frequency domain for a residual signal (or a residual block) based on DCT type 2 can be applied to generate transform coefficients.
- the spatial domain for a residual signal (or residual block) based on DCT type 2, DST type 7, DCT type 8, and / or DST type 1 can be applied to generate the transform coefficients (or the primary transform coefficients).
- DCT type 2, DST type 7, DCT type 8, and DST type 1 and the like can be called a conversion type, a conversion kernel, or a conversion core.
- the DCT / DST conversion types can be defined based on basis functions, and the basis functions can be expressed as shown in the following table.
- a vertical conversion kernel and a horizontal conversion kernel for a target block among the conversion kernels may be selected, and a vertical conversion for the target block is performed based on the vertical conversion kernel ,
- the horizontal conversion of the target block may be performed based on the horizontal conversion kernel.
- the horizontal conversion may represent a conversion of horizontal components of the target block
- the vertical conversion may represent a conversion of vertical components of the target block.
- the vertical conversion kernel / horizontal conversion kernel may be adaptively determined based on a prediction mode of a target block (CU or sub-block) encompassing a residual block and / or a conversion index indicating a conversion subset.
- the adaptive multi-core transformation may be applied when both the width and the height of the target block are less than or equal to 64, and whether the adaptive multi-core transformation of the target block is applied May be determined based on the CU level flag.
- the existing conversion method described above can be applied. That is, when the CU level flag is 0, a transform from a spatial domain to a frequency domain is applied to a residual signal (or a residual block) based on the DCT type 2 to generate transform coefficients, The coefficients can be encoded.
- the target block may be a CU. If the CU level flag is 0, the adaptive multi-core transform can be applied to the target block.
- AMT_TU_vertical_flag (or EMT_TU_vertical_flag) may represent a syntax element of the AMT vertical flag.
- AMT_TU_horizontal_flag (or EMT_TU_horizontal_flag) may denote a syntax element of the AMT horizontal flag.
- the AMT vertical flag may indicate one of the transform kernel candidates included in the transform subset for the vertical transform kernel, and the transform kernel candidate indicated by the AMT vertical flag may be derived as a vertical transform kernel for the target block .
- the AMT horizontal flag may indicate one of the transform kernel candidates included in the transform subset for the horizontal transform kernel, and the transform kernel candidate pointed to by the AMT horizontal flag may include a horizontal transform kernel for the target block, . ≪ / RTI > Meanwhile, the AMT vertical flag may be referred to as an MTS vertical flag, and the AMT horizontal flag may be referred to as an MTS horizontal flag.
- three transform subsets may be predefined, and one of the transform subsets may be derived as a transform subsets for the vertically transformed kernel based on the intra prediction mode applied to the target block. Also, one of the transform subsets may be derived as a transformed subset for the horizontal transform kernel based on an intra prediction mode applied to the target block.
- the predetermined transform subsets may be derived as shown in the following table.
- a transform subset having an index value of 0 can represent a transform subset including DST type 7 and DCT type 8 as conversion candidate candidates
- a transform subset having an index value of 1 can represent DST type 7 and DST type 1 May represent the transform subsets included as candidate transform kernels
- the transform subsets with index value two may represent transform subsets that include DST type 7 and DCT type 8 as transform kernel candidates.
- the transformed subset for the vertically transformed kernel derived based on the intra prediction mode applied to the target block and the transformed subset for the transformed kernel can be derived as shown in the following table.
- V represents the transform subsets for the vertically transformed kernels and H represents the transform subsets for the horizontal transform kernels.
- the transformed subset for the vertically transformed kernel and the transformed subset for the transformed kernel based on the intra- A transform subset can be derived. Thereafter, the transformed kernel candidate pointed to by the AMT vertical flag of the target block among the transformed kernel candidates included in the transformed subset for the vertically transformed kernel may be derived as a vertically transformed kernel of the target block, The transform kernel candidate indicated by the AMT horizontal flag of the target block among the transform kernel candidates included in the transform subset may be derived as a horizontal transform kernel of the target block.
- the AMT flag may be referred to as an MTS flag.
- the intra-prediction mode includes two non-directional (non-angular) intra prediction modes and 65 directional (or angular) intra prediction modes Lt; / RTI >
- the non-directional intra-prediction modes may include a planar intra-prediction mode and a 1-DC intra-prediction mode, and the directional intra-prediction modes may include 65 intra-prediction modes 2 to 66 .
- the present invention can be applied to a case where the number of intra prediction modes is different.
- the intra prediction mode # 67 may be further used, and the intra prediction mode # 67 may be a linear mode (LM) mode.
- LM linear mode
- FIG. 6 exemplarily shows intra-directional modes of 65 prediction directions.
- an intra-prediction mode having horizontal directionality and an intra-prediction mode having vertical directionality can be distinguished from the intra-prediction mode # 34 having the left upward diagonal prediction direction.
- H and V in FIG. 6 indicate the horizontal direction and the vertical direction, respectively, and the numbers from -32 to 32 indicate displacements of 1/32 unit on the sample grid position.
- the intra-prediction modes 2 to 33 have a horizontal direction, and the intra-prediction modes # 34 to # 66 have a vertical direction.
- the intra prediction mode 18 and the intra prediction mode 50 respectively represent a horizontal intra prediction mode and a vertical intra prediction mode
- a second intra prediction mode is a left downward diagonal intra prediction mode
- the intra prediction mode 34 is referred to as a left upward diagonal intra prediction mode
- the intra prediction mode 66 is referred to as a right upward diagonal intra prediction mode.
- the transform unit may perform the quadratic transform based on the (primary) transform coefficients to derive the (secondary) transform coefficients (S520). If the first order transformation is a spatial domain to a frequency domain transformation, the second order transformation can be regarded as a frequency domain to frequency domain transformation.
- the quadratic transformation may include a non-separable transform. In this case, the quadratic transformation may be called a non-separable secondary transform (NSST) or a mode-dependent non-separable secondary transform (MDNSST).
- the non-separable quadratic transformation transforms the (primary) transform coefficients derived through the primary transformation on the basis of a non-separable transform matrix and transforms the transform coefficients for the residual signal Gt; < / RTI > second order transform coefficients).
- the non-separable quadratic transformation generates the transform coefficients (or the second-order transform coefficients) by transforming them together without separating the vertical component and the horizontal component of the (primary) transform coefficients based on the non- Can be represented.
- the non-isolated quadratic transformation can be applied to the top-left region of a block composed of (primary) transform coefficients (hereinafter referred to as a transform coefficient block or a target block).
- the 8 ⁇ 8 non-separable quadratic transform is applied to the upper left 8 ⁇ 8 region (hereinafter referred to as upper left target region) Lt; / RTI >
- upper left target region Lt
- RTI > the width W and the height H of the conversion coefficient block are both 4 or more and the width W or height H of the conversion coefficient block is smaller than 8
- the transform can be applied to the upper left corner min (8, W) x min (8, H) region of the transform coefficient block.
- the non-separating quadratic transformation can be performed as follows.
- the 4x4 input block X may be expressed as follows.
- the quadratic non-separable conversion can be calculated as follows.
- T represents a 16x16 (non-separating) transformation matrix
- the 16 ⁇ 1 transform coefficient vector Can be derived May be re-organized into 4x4 blocks through scan orders (horizontal, vertical, diagonal, etc.).
- the above calculation may be used for calculating the non-separating quadratic transformation, for example, HyperCube-Givens Transform (HyGT) to reduce the computational complexity of the non-separating quadratic transformation.
- HyGT HyperCube-Givens Transform
- the non-separation quadratic transformation may be a mode-dependent transform kernel (or a transform core, transform type).
- the mode may comprise an intra prediction mode and / or an inter prediction mode.
- the non-separable quadratic transformation can be performed based on the 8x8 transform or the 4x4 transform determined based on the width (W) and the height (H) of the transform coefficient block. That is, the non-separation secondary conversion may be performed based on an 8x8 sub-block size or a 4x4 sub-block size.
- the mode-based transform kernel selection 35 sets of three non-isolated quadratic transformation kernels for non-quadratic quadratic transforms for both the 8x8 subblock size and the 4x4 subblock size Lt; / RTI > That is, 35 transform sets are configured for an 8x8 sub-block size, and 35 transform sets for a 4x4 sub-block size.
- each of the 35 transform sets for the 8x8 sub-block size may include three 8x8 transform kernels, in which case each of the 35 transform sets for the 4x4 sub- 4 conversion kernels may be included.
- the transformed sub-block size, the number of sets and the number of transform kernels in the set may be, for example, a size other than 8x8 or 4x4, or n sets may be constructed, and k Conversion kernels may also be included.
- the transform set may be referred to as an NSST set, and the transform kernel in the NSST set may be referred to as an NSST kernel. Selection of a particular set of transform sets may be performed based on, for example, an intra prediction mode of a target block (CU or sub-block).
- mapping between the 35 transform sets and the intra prediction modes may be represented as shown in the following table, for example.
- the second transformation may not be applied to the target block.
- one of k transform kernels in the particular set may be selected via the non-separating quadratic transform index.
- the encoding apparatus can derive a non-separating quadratic conversion index indicating a specific conversion kernel based on a rate-distortion (RD) check, and signaling the non-separating quadratic conversion index to the decoding apparatus.
- the decoding device may select one of k transform kernels in a particular set based on the non-separating quadratic transform index.
- an NSST index value of 0 may indicate the first non-isolated secondary transformation kernel
- an NSST index value of 1 may point to a second non-isolated secondary transformation kernel
- an NSST index value of 2 may point to a third non- Lt; / RTI >
- an NSST index value of 0 may indicate that the first non-separating quadratic transformation is not applied to the target block
- the NSST index values 1 to 3 may indicate the three transform kernels.
- the transforming unit may perform the non-separating quadratic transform based on the selected transform kernels and obtain (second) transform coefficients.
- the transform coefficients may be derived as transform coefficients quantized through the quantizer as described above, encoded and transmitted to the inverse quantization / inverse transformer in the signaling and encoding device to the decoding device.
- the (primary) transform coefficients which are the outputs of the primary transform (separation) can be derived as the transform coefficients quantized through the quantization section as described above, To the inverse quantization / inverse transformer in the signaling and encoding apparatus.
- the inverse transform unit may perform a series of procedures in the reverse order of the procedure performed in the transform unit.
- the inverse transform unit receives the transform coefficients (dequantized), performs the quadratic transformation to derive the transform coefficients from the quadratic transform coefficients, Conversion can be performed to obtain a residual block (residual samples).
- the primary transform coefficients may be referred to as modified transform coefficients in the inverse transform unit.
- the encoding apparatus and the decoding apparatus generate the restored block based on the residual block and the predicted block, and generate the restored picture based on the restored block.
- the transform coefficients (inversely quantized) are received and the primary (decoupled) transform is performed to obtain the residual block (residual samples) .
- the encoding apparatus and the decoding apparatus generate the restored block based on the residual block and the predicted block, and generate the restored picture based on the restored block.
- the above-described non-separating quadratic transformation may not be applied to the block coded in the conversion skip mode.
- the non-segregated quadratic transformation may not be applied to the block coded in the transform skip mode in the target CU .
- the target CU including blocks of all the components luma component, chroma component, etc.
- the NSST index may not be signaled.
- the coding process of concrete transform coefficients is as follows.
- FIGS. 7A and 7B are flowcharts illustrating a coding process of a transform coefficient according to an embodiment.
- FIGS. 7A and 7B can be performed by the encoding apparatus 100 or the decoding apparatus 300 disclosed in FIGS. 1 and 3, and more specifically, the entropy encoding unit 130 and the entropy encoding unit 130 disclosed in FIG. May be performed by the entropy decoding unit 310 disclosed in FIG. Therefore, detailed description overlapping with the above-described contents in FIG. 1 or FIG. 3 will be omitted or simplified.
- FIG. 7A shows a process of encoding a transform coefficient.
- the encoding apparatus 100 may determine whether a flag indicating whether at least one non-zero transform coefficient among the transform coefficients for the target block exists indicates 1 (S700). When the flag indicating whether or not at least one non-zero transform coefficient exists among the transform coefficients for the target block indicates 1, at least one non-zero transform coefficient among the transform coefficients for the target block may exist. Conversely, when the flag indicating whether at least one non-zero transform coefficient among the transform coefficients for the target block exists indicates 0, the transform coefficients for the target block may represent all zeros.
- the flag indicating whether or not at least one non-zero conversion coefficient among the conversion coefficients for the target block is present may be represented by, for example, a cbf flag.
- the cbf flag may include cbf_luma [x0] [y0] [trafoDepth] for the luma block and cbf_cb [x0] [y0] [trafoDepth] and cbf_cr [x0] [y0] [trafoDepth] flags for the chroma block.
- the array indices x0 and y0 indicate the positions of the upper left luma / chroma samples of the target block with respect to the top-left luma / chroma samples of the current picture
- the array index trafoDepth indicates the positions of the left- It can mean divided levels.
- the blocks with the trafoDepth indicating 0 correspond to the coding blocks, and if the coding blocks and the transform blocks are defined identically, the trafoDepth can be regarded as 0.
- the encoding apparatus 100 sets the transform coefficients for the target block May be encoded (S710).
- the information on the transform coefficients for the target block includes, for example, information on the position of the last non-zero transform coefficient, group flag information indicating whether the non-zero transform coefficient is included in the subgroup of the target block, And information on the coefficient. A detailed description of each piece of information will be given later.
- the encoding apparatus 100 may determine whether it is a condition for performing NSST (S720). More specifically, the encoding apparatus 100 can determine whether or not it meets the condition for encoding the NSST index.
- the NSST index may be referred to as a transform index, for example.
- the encoding apparatus 100 may encode the NSST index (S730). More specifically, the encoding apparatus 100 can encode the NSST index if it is determined that the condition is satisfied to encode the NSST index.
- the encoding apparatus 100 performs the process of S710, S720, and S730 The operation can be omitted.
- the encoding apparatus 100 may skip operation in operation S730.
- FIG. 7B shows a decoding process of the transform coefficients.
- the decoding apparatus 300 may determine whether a flag indicating whether at least one non-zero transform coefficient among the transform coefficients for the target block exists indicates 1 (S740). When the flag indicating whether or not at least one non-zero transform coefficient exists among the transform coefficients for the target block indicates 1, at least one non-zero transform coefficient among the transform coefficients for the target block may exist. Conversely, when the flag indicating whether at least one non-zero transform coefficient among the transform coefficients for the target block exists indicates 0, the transform coefficients for the target block may represent all zeros.
- the decoding apparatus 300 calculates the transform coefficients (S750). ≪ / RTI >
- the decoding apparatus 300 can determine whether the condition for performing NSST is satisfied (S760). More specifically, the decoding apparatus 300 can determine whether the NSST index corresponds to a condition for decoding from the bitstream.
- step S760 If it is determined in step S760 that the condition for performing the NSST is satisfied, the decoding apparatus 300 according to the embodiment may decode the NSST index (step S770).
- the decoding apparatus 300 may perform the process of steps S750, S760, and S770 The operation can be omitted.
- step S760 if it is determined in step S760 that the condition for performing the NSST does not correspond to the condition for performing the NSST, the decoding apparatus 300 according to the embodiment may skip the operation according to step S770.
- the present invention proposes various NSST index coding methods.
- the NSST index range may be determined based on a specific condition.
- a range of values of the NSST index can be determined based on a specific condition.
- the maximum value of the NSST index can be determined based on the specific condition.
- the range of values of the NSST index can be determined based on the block size.
- the block size may be defined as a minimum (W, H).
- W may represent a width
- H may represent a height.
- the range of the value of the NSST index can be determined by comparing the width of the target block with the W, and comparing the height of the target block with the minimum H.
- the block size may be defined as (W * H) which is the number of samples of the block.
- the range of the value of the NSST index can be determined by comparing W * H, which is the number of samples of the target block, with a specific value.
- the range of the value of the NSST index can be determined based on, for example, a shape of a block, i.e., a block type.
- the block type may be defined as a square block or a non-square block.
- the range of values of the NSST index can be determined based on whether the target block is a square block or a non-square block.
- the block type can be defined as a ratio of a long side of the block (long side of the width and height) to a short side.
- the range of the value of the NSST index can be determined through comparison between the ratio of the long side and the short side of the target block and a preset threshold value (for example, 2 or 3).
- the ratio may represent a value obtained by dividing the long side by the short side.
- the range of values of the NSST index may be determined by comparing the width divided by the height and the predetermined threshold.
- the range of the value of the NSST index can be determined by comparing the value obtained by dividing the height by the width and the preset threshold value.
- a range of values of the NSST index can be determined based on an intra prediction mode applied to a block.
- the range of values of the NSST index may be determined based on whether the intra prediction mode applied to the target block is a non-directional intra prediction mode or a directional intra prediction mode.
- the range of the value of the NSST index may be determined based on whether the intra prediction mode applied to the target block is an intra prediction mode included in the category A (category A) or the category B (category B) .
- the category A may include a second intra prediction mode, a 10th intra prediction mode, an 18th intra prediction mode, a 26th intra prediction mode, a 34th intra prediction mode, a 42th intra prediction mode, , 58 intra prediction mode, and 66 intra prediction mode
- the category B may include intra prediction modes other than the intra prediction mode included in the category A.
- the intra prediction mode included in the category A may be preset, and the category A and the category B may be set to include an intra prediction mode different from the example described above.
- the range of values of the NSST index may be determined based on the AMT factor of the block.
- the AMT factor may be referred to as an MTS factor.
- the AMT factor may be defined by the AMT flag described above.
- the range of the value of the NSST index may be determined based on the value of the AMT flag of the target block.
- the AMT factor may be defined by the AMT vertical flag and / or the AMT horizontal flag described above.
- the range of the value of the NSST index may be determined based on the value of the AMT vertical flag and / or the AMT horizontal flag of the target block.
- the AMT factor may be defined as a transform kernel applied in a multi-core transform.
- the range of the value of the NSST index can be determined based on the transform kernel applied in the multi-core transform of the target block.
- the range of values of the NSST index may be determined based on the components of the block. For example, the range of the value of the NSST index for the luma block of the target block and the range of the value of the NSST index for the chroma block of the target block may be different from each other.
- the range of the value of the NSST index may be determined based on the combination of the above-described specific conditions.
- the range of the value of the NSST index determined based on the specific condition, that is, the maximum value of the NSST index may be variously set.
- the maximum value of the NSST index based on the specific condition may be determined as R1, R2, or R3. Specifically, when the specific condition corresponds to the category A, the maximum value of the NSST index may be derived as R1, and when the specific condition corresponds to the category B, the maximum value of the NSST index may be derived as R2 And if the specific condition corresponds to category C, the maximum value of the NSST index can be derived as R3.
- R1 for the category A, R2 for the category B, and R3 for the category C can be derived as shown in the following table.
- the R1, R2, and R3 may be pre-set.
- the relationship between R1, R2, and R3 may be derived as the following equation.
- R1 may be greater than or equal to 0, R2 may be greater than R1, and R3 may be greater than R2. Meanwhile, if R1 is 0 and the maximum value of the NSST index for the target block is determined as R1, the NSST index may not be signaled and the NSST index value may be inferred to be 0 .
- NSST when NSST is applied, the distribution of the non-zero transform coefficients among the transform coefficients can be changed.
- RST reduced secondary transform
- the RST may represent a quadratic transformation using a simplified transformation matrix as a non-separation transformation matrix
- the simplified transformation matrix may be an R-dimensional vector in which an N-dimensional vector is located in another space, , Where R is less than N.
- RTI ID 0.0 >
- the N may mean the length of one side of the block to which the transformation is applied or the total number of transform coefficients corresponding to the block to which the transformation is applied
- the simplification factor may mean an R / N value.
- the simplification factor may be referred to by various terms such as a reduced factor, a reduction factor, a reduced factor, a simplified factor, and a simple factor.
- R may be referred to as a reduced coefficient, but in some cases the simplification factor may also mean R. [ In some cases, the simplification factor may also mean an N / R value.
- the size of the simplified transformation matrix according to an embodiment is RxN smaller than the size NxN of the normal transformation matrix and can be defined as Equation (5) below.
- the transform coefficient of R + 1 to N can implicitly become 0 since the simplification transform matrix of RxN size is applied to the quadratic transform.
- the value of the transform coefficient from R + 1 to N may be zero.
- the transform coefficients from R + 1 to N may represent an Nth transform coefficient from the (R + 1) th transform coefficient among the transform coefficients.
- the arrangement of the transform coefficients of the target block can be described as follows.
- FIG. 8 is a diagram for explaining the arrangement of transform coefficients based on a target block according to an embodiment of the present invention.
- the description of the transform described below in Fig. 8 can be applied to the inverse transform as well.
- an NSST an example of a secondary transformation
- a simplified transformation can be performed.
- the 16x16 block shown in FIG. 8 represents the target block 800
- the 4x4 blocks labeled A through P may represent the subgroup of the target block 800.
- the primary transformation can be performed over the entire range of the object block 800 and after the primary transformation is performed, the NSST is applied to the 8x8 block (hereinafter referred to as the upper left target region) constituted by the subgroups A, B, E and F .
- the NSST based on the simplified transform is performed, only the NSST transform coefficients of R (where R represents the simplification coefficient and R is smaller than N) are derived, The transform coefficients may be determined to be 0, respectively.
- the primary transform coefficients on which the NSST is not performed based on the simplified transform are allocated to the respective blocks included in the subgroups C, D, G, H, I, J, K, L, M, N, .
- FIG. 9 shows an example of scanning R + 1 to N conversion coefficients.
- a 16x64 size simplified transformation matrix may be applied to the quadratic transformation of 64 samples of the upper left target region of the target block.
- the value of the conversion coefficient from 17 to 64 (N) should be zero.
- the RST is not applied and the value of the NSST index is derived as zero without additional signaling .
- the decoding apparatus can decode the transform coefficients of the target block, scan the transform coefficients from 17 to 64 among the transform coefficients, and when a non-zero transform coefficient is derived, The value of the NSST index can be derived as 0 without signaling the syntax element. On the other hand, if there is no non-zero transform coefficient among the transform coefficients from 17 to 64, the decoding apparatus can receive and decode the NSST index.
- 10A and 10B are flowcharts illustrating a coding process of an NSST index according to an embodiment.
- FIG. 10A shows an encoding process of the NSST index.
- the encoding apparatus can encode a transform coefficient for a target block (S1000).
- the encoding device may perform entropy encoding on the quantized transform coefficients.
- Entropy encoding may include, for example, an encoding method such as exponential Golomb, context-adaptive variable length coding (CAVLC), context-adaptive binary arithmetic coding (CABAC)
- the encoding apparatus can determine whether an (explicit) NSST index for the target block is coded (S1010).
- the explicit NSST index may represent an NSST index transmitted to the decoding apparatus. That is, the encoding apparatus can determine whether to generate the NSST index to be signaled. In other words, the encoding device can determine whether to allocate bits for a syntax element for the NSST index. If the decoding apparatus can derive the value of the NSST index even though the NSST index is not signaled as in the above-described embodiment, the encoding apparatus may not code the NSST index. A specific procedure for determining whether or not the NSST index is coded will be described later.
- the encoding apparatus can encode the NSST index (S1020).
- FIG. 10B shows a decoding process of the NSST index.
- the decoding apparatus may decode the transform coefficients for the target block (S1030).
- the decoding apparatus may determine whether an (explicit) NSST index for the target block is coded (S1040).
- the explicit NSST index may indicate an NSST index signaled from the encoding device.
- the NSST index may not be signaled from the encoding apparatus if the decoding apparatus can derive the value of the NSST index even though the NSST index is not signaled as in the above embodiment.
- a specific procedure for determining whether or not the NSST index is coded will be described later.
- the encoding apparatus may decode the NSST index (S1040).
- FIG. 11 shows an example of determining whether the NSST index is coded.
- the encoding apparatus / decoding apparatus can determine whether the condition for coding the NSST index for the target block is met (S1100). For example, when the cbf flag for the target block indicates 0, the encoding apparatus / decoding apparatus can determine that the NSST index for the target block is not coded. Alternatively, when the target block is coded in the conversion skip mode or when the number of non-zero transform coefficients among the transform coefficients for the target block is smaller than a predetermined threshold value, the encoding device / It can be determined that the NSST index is not coded.
- the predetermined threshold may be 2.
- the encoding / decoding apparatus may scan the transform coefficients R + 1 to N (S1110).
- the R + 1 to N transform coefficients may represent R + 1th to Nth transform coefficients in the scan order among the transform coefficients.
- the encoding apparatus / decoding apparatus can determine whether a non-zero transform coefficient among the transform coefficients from R + 1 to N is derived (S1120). When a non-zero transform coefficient among the transform coefficients from R + 1 to N is derived, the encoding apparatus / decoding apparatus can determine that the NSST index for the target block is not coded. In this case, the encoding apparatus / decoding apparatus can derive the value of the NSST index for the target block by zero. In other words, for example, if the NSST index with a value of 0 indicates that the NSST is not applied, the encoding device / decoding device may not perform the NSST on the upper left target area of the target block.
- the encoding apparatus can encode the NSST index of the target block, and the decoding apparatus can perform NSST The index can be decoded.
- a method of using the NSST index common to the components (luma component, chroma Cb component, chroma Cr component) of the target block may be proposed.
- the same NSST index may be used for the chroma Cb block of the target block and the chroma Cr block of the target block.
- the same NSST index may be used for the luma block of the target block, the chroma Cb block of the target block, and the chroma Cr block of the target block.
- the encoding apparatus calculates R + 1 to N transform coefficients of all components (luma block of the target block, chroma Cb block, chroma Cr block) If at least one non-zero transform coefficient is derived, the value of the NSST index can be derived as 0 without encoding the NSST index. Further, the decoding apparatus can scan R + 1 to N transform coefficients of all components (luma block, chroma Cb block, chroma Cr block of the target block), and when at least one non-zero transform coefficient is derived , It is possible to derive the value of the NSST index as 0 without decoding the NSST index.
- 12 shows the upper left target region of the luma block, the upper left target region of the chroma Cb block, and the upper left target region of the chroma Cr block. Therefore, a 16x64 size simplified transformation matrix may be applied to the quadratic transformation of 64 samples of each of the upper left target region of the luma block, the upper left target region of the chroma Cb block, and the upper left target region of the chroma Cr block.
- the values of the conversion coefficients from 17 to 64 (N) Should be zero.
- the RST is not applied and the value of the NSST index can be derived as zero without additional signaling have.
- the decoding apparatus can decode the transform coefficients for all components of the object block, scan the transform coefficients of the luma block, the chroma Cb block, and the chroma Cr block of the decoded transform coefficients from 17 to 64 , If a non-zero transform coefficient is derived, the value of the NSST index can be derived as 0 without signaling of a separate syntax element to the NSST index. On the other hand, if there is no non-zero transform coefficient among the transform coefficients from 17 to 64, the decoding apparatus can receive and decode the NSST index.
- the NSST index may be used as an index for the luma block, the chroma Cb block, and the chroma Cr block.
- the NSST_Idx_indicator may indicate a syntax element for the NSST index indicator.
- the NSST index indicator may be coded with a CTU (Coding Tree Unit) level, and the NSST index indicator may indicate whether NSST is applied to the target CTU. That is, the NSST index indicator may indicate whether NSST is available in the target CTU.
- the NSST index indicator for the target CTU is enabled (when the NSST is available in the target CTU), that is, when the value of the NSST index indicator is 1, the CU Or an NSST index for TU may be coded.
- the NSST index indicator for the target CTU When the NSST index indicator for the target CTU is not activated (when the NSST is not available in the target CTU), that is, when the value of the NSST index indicator is 0, the CU or TU included in the target CTU
- the NSST index may not be coded.
- the NSST index indicator may be coded at the CTU level as described above, or may be coded at a sample group level of any other size.
- the NSST index indicator may be coded with a CU (Coding Unit) level.
- FIG. 13 schematically shows an image encoding method by the encoding apparatus according to the present invention.
- the method disclosed in Fig. 13 can be performed by the encoding apparatus disclosed in Fig.
- S1300 of FIG. 13 may be performed by the subtraction unit of the encoding apparatus
- S1310 may be performed by the transform unit of the encoding apparatus
- S1320 through S1330 may be performed by the entropy encoding unit of the encoding apparatus.
- a process of deriving a prediction sample may be performed by the predicting unit of the encoding apparatus.
- the encoding apparatus derives residual samples of the target block (S1300). For example, the encoding apparatus can determine whether to perform inter prediction or intra prediction on a target block, and determine a specific inter prediction mode or a specific intra prediction mode based on the RD cost. According to the determined mode, the encoding apparatus can derive prediction samples for the target block, and derive the residual samples through addition of the original samples with respect to the target block and the prediction samples.
- the encoding apparatus converts the residual samples to derive transform coefficients of the target block (S1310).
- the encoding apparatus can determine whether NSST is applied to the target block.
- the encoding device can perform the core transformation on the residual samples to derive the modified transform coefficients, and based on the simplified transformation matrix,
- the transform coefficients of the target block may be derived by performing NSST on the transform coefficients.
- the modified transform coefficients other than the modified transform coefficients located in the left upper end region of the target block may be directly derived as the transform coefficients of the target block.
- the size of the simplified transformation matrix may be RxN, N may be a number of samples of the upper left target region, R may be a reduced coefficient, and R may be smaller than N.
- the core transformation of the residual samples may be performed as follows.
- the encoding apparatus may determine whether to apply adaptive multiple core transform (AMT) to the target block.
- AMT adaptive multiple core transform
- an AMT flag indicating whether or not the adaptive multi-core transform of the target block is applied may be generated. If the AMT is not applied to the target block, the encoding apparatus can derive DCT type 2 as a transform kernel for the target block, perform conversion on the residual samples based on the DCT type 2
- the modified transform coefficients can be derived.
- the encoding device may configure a transform subset for the horizontal transform kernel and a transform subset for the vertical transform kernel, and derive a horizontal transform kernel and a vertical transform kernel based on the transform subsets And may convert the residual samples based on the horizontal conversion kernel and the vertical conversion kernel to derive the modified conversion coefficients.
- the transformed subset for the horizontal transform kernel and the transformed subset for the vertically transformed kernel may include DCT type 2, DST type 7, DCT type 8, and / or DST type 1 as candidates.
- conversion index information may be generated, and the conversion index information may include an AMT horizontal flag indicating the horizontal conversion kernel and an AMT vertical flag indicating the vertical conversion kernel.
- the conversion kernel may be called a conversion type or a conversion core.
- the encoding device may perform a core transformation on the residual samples to derive the transform coefficients of the target block.
- the core transformation of the residual samples may be performed as follows.
- the encoding apparatus may determine whether to apply adaptive multiple core transform (AMT) to the target block.
- AMT adaptive multiple core transform
- an AMT flag indicating whether or not the adaptive multi-core transform of the target block is applied may be generated. If the AMT is not applied to the target block, the encoding apparatus can derive DCT type 2 as a transform kernel for the target block, perform conversion on the residual samples based on the DCT type 2
- the transform coefficients can be derived.
- the encoding device may configure a transform subset for the horizontal transform kernel and a transform subset for the vertical transform kernel, and derive a horizontal transform kernel and a vertical transform kernel based on the transform subsets And convert the residual samples based on the horizontal conversion kernel and the vertical conversion kernel to derive the transform coefficients.
- the transformed subset for the horizontal transform kernel and the transformed subset for the vertically transformed kernel may include DCT type 2, DST type 7, DCT type 8, and / or DST type 1 as candidates.
- conversion index information may be generated, and the conversion index information may include an AMT horizontal flag indicating the horizontal conversion kernel and an AMT vertical flag indicating the vertical conversion kernel.
- the conversion kernel may be called a conversion type or a conversion core.
- the encoding apparatus determines whether the NSST index is encoded (S1320).
- the encoding apparatus may scan the (R + 1) -th to N-th transform coefficients among the transform coefficients of the target block, and may include a non-zero transform coefficient in the (R + 1) , It can be determined not to encode the NSST index.
- N is the number of samples of the upper left target region
- R is a reduced coefficient
- R may be smaller than N.
- the N may be derived as a product of a width and a height of the upper left target region.
- the encoding apparatus may determine to encode the NSST index.
- the information on the transform coefficients may include a syntax element for the NSST index. That is, the syntax element for the NSST index may be encoded. In other words, a bit for a syntax element for the NSST index may be allocated.
- the encoding apparatus can determine whether the NSST can be performed, and if the NSST can be performed, the encoding apparatus can determine to encode the NSST index for the target block.
- an NSST index indicator for a target CTU including the target block may be generated from a bitstream, and the NSST index indicator may indicate whether NSST is applied to the target CTU. If the value of the NSST index indicator is 1, the encoding apparatus can determine to encode the NSST index for the target block. If the value of the NSST index indicator is 0, the decoding apparatus calculates the NSST index As shown in FIG.
- the NSST index indicator may be signaled to the CTU level, or the NSST index indicator may be signaled to the CU level or other higher level, as in the example described above.
- the NSST index may be used for a plurality of components of the target block.
- the NSST index may be used for transform coefficients of a luma block of the target block, transform coefficients of a chroma Cb block, and inverse transform coefficients of a chroma Cr block.
- R + 1 th to N th transform coefficients of the luma block, R + 1 th to N th transform coefficients of the chroma Cb block, and R + 1 th to N th transforms of the chroma Cr block If the coefficients can be scanned and the non-zero transform coefficient is included in the scanned transform coefficients, the NSST index can be determined to be unencoded.
- the NSST index may be determined to be encoded.
- the information on the transform coefficients may include a syntax element for the NSST index. That is, the syntax element for the NSST index may be encoded. In other words, a bit for a syntax element for the NSST index may be allocated.
- the NSST index may be used for transform coefficients of the luma block of the target block and the transform coefficients of the chroma Cb block.
- the (R + 1) th to Nth transform coefficients of the luma block and the (R + 1) th to Nth transform coefficients of the chroma Cb block may be scanned, If the transform coefficient is included, the NSST index may be determined to not be encoded. If the non-zero transform coefficient is not included in the scanned transform coefficients, the NSST index may be determined to be encoded.
- the information on the transform coefficients may include a syntax element for the NSST index. That is, the syntax element for the NSST index may be encoded. In other words, a bit for a syntax element for the NSST index may be allocated.
- the NSST index may be used for transform coefficients of the luma block of the target block and the transform coefficients of the chroma Cr block.
- the (R + 1) th to Nth transform coefficients of the luma block and the (R + 1) th to Nth transform coefficients of the chroma Cr block may be scanned, If the transform coefficient is included, the NSST index may be determined to not be encoded. If the non-zero transform coefficient is not included in the scanned transform coefficients, the NSST index may be determined to be encoded.
- the information on the transform coefficients may include a syntax element for the NSST index. That is, the syntax element for the NSST index may be encoded. In other words, a bit for a syntax element for the NSST index may be allocated.
- a range of NSST indices can be derived based on a specific condition.
- the maximum value of the NSST index may be derived based on the specific condition, and the range may be derived from 0 to the derived maximum value.
- the value of the derived NSST index may be included in the range.
- the range of the NSST index may be derived based on the size of the target block.
- the minimum width and the minimum height may be preset, and the range of the NSST index may be derived based on the width and the minimum width of the target block, the height of the target block, and the minimum height.
- the range of the NSST index can be derived based on the number of samples and the specific value of the target block. The number of samples may be a value obtained by multiplying a width of the target block by a height, and the specific value may be preset.
- the range of the NSST index may be derived based on the type of the target block. Specifically, the range of the NSST index can be derived based on whether the target block is a non-square block. Also, the range of the NSST index can be derived based on the ratio between the width and height of the target block and the specific value. The ratio between the width and height of the target block may be a value obtained by dividing the longer side of the width and height of the target block by the shorter side, and the specific value may be set in advance.
- the range of the NSST index can be derived based on the intra prediction mode of the target block. Specifically, the range of the NSST index can be derived based on whether the intra-prediction mode of the target block is a non-directional intra-prediction mode or a directional intra-prediction mode. In addition, the range of the NSST index may be derived based on whether the intra prediction mode of the target block is an intra prediction mode included in the category A (category A) or the category B (category B). Here, the intra-prediction mode included in the category A and the intra-prediction mode included in the category B may be preset.
- the category A may include a second intra prediction mode, a 10th intra prediction mode, an 18th intra prediction mode, a 26th intra prediction mode, a 34th intra prediction mode, a 42th intra prediction mode, An intra prediction mode and a 66th intra prediction mode
- the category B may include intra prediction modes other than the intra prediction mode included in the category A.
- the range of the NSST index may be derived based on information on a core transform of the target block.
- the range of the NSST index may be derived based on an AMT flag indicating whether Adaptive Multiple Core Transform (AMT) is applied.
- AMT Adaptive Multiple Core Transform
- the range of the NSST index can be derived based on the AMT horizontal flag indicating the horizontal conversion kernel and the AMT vertical flag indicating the vertical conversion kernel.
- the NSST index may indicate that the NSST is not applied to the target block.
- the encoding apparatus encodes information on the transform coefficients (S1330).
- the information on the transform coefficients may include information on the size, position, and the like of the transform coefficients.
- the information on the transform coefficients may further include the NSST index, the transform index information, and / or the AMT flag.
- the image information including information on the transform coefficients may be output in the form of a bit stream.
- the image information may further include the NSST index indicator and / or prediction information.
- the prediction information may include prediction mode information and information on motion information (e.g., when inter prediction is applied) as information related to the prediction procedure.
- the output bitstream may be transferred to a decoding device via a storage medium or a network.
- FIG. 14 schematically shows an encoding apparatus for performing a video encoding method according to the present invention.
- the method disclosed in Fig. 13 can be performed by the encoding apparatus disclosed in Fig.
- the adding unit of the encoding apparatus of FIG. 14 may perform S1300 of FIG. 13
- the converting unit of the encoding apparatus may perform S1310
- the entropy encoding unit of the encoding apparatus may perform S1320 of FIG. S1330 can be performed.
- a process of deriving a prediction sample may be performed by the predicting unit of the encoding apparatus.
- FIG. 15 schematically shows a video decoding method by a decoding apparatus according to the present invention.
- the method disclosed in Fig. 15 can be performed by the decoding apparatus disclosed in Fig.
- S15400 to S1510 in FIG. 15 may be performed by an entropy decoding unit of the decoding apparatus
- S1520 may be performed by an inverse transform unit of the decoding apparatus
- S1530 may be performed by an adding unit of the decoding apparatus.
- a process of deriving a predictive sample may be performed by a predicting unit of the decoding apparatus.
- the decoding apparatus derives transform coefficients of the target block from the bitstream (S1500).
- the decoding apparatus may derive transform coefficients of the target block by decoding information on transform coefficients of the target block received through the bitstream.
- the information on the transform coefficients of the received target block may be referred to as residual information.
- the transform coefficients of the target block may include transform coefficients of a luma block of the target block, transform coefficients of a chroma Cb block of the target block, and transform coefficients of a chroma Cr block of the target block.
- the decoding apparatus derives an NSST (Non-separable Secondary Transform) index for the target block (S1510).
- NSST Non-separable Secondary Transform
- the decoding apparatus may scan R + 1 th to N th transform coefficients among the transform coefficients of the target block, and a non-zero transform coefficient may be included in the R + 1 th to N th transform coefficients.
- the value of the NSST index can be derived as zero.
- N is the number of samples of the upper left target region of the target block
- R is a reduced coefficient
- R may be smaller than N.
- the N may be derived as a product of a width and a height of the upper left target region.
- the decoding apparatus parses the syntax element of the NSST index included in the bitstream, ) To derive the value of the NSST index. That is, when the non-zero transform coefficient is not included in the (R + 1) -th to N-th transform coefficients, the bitstream may include a syntax element for the NSST index, The value of the NSST index can be derived by parsing the received syntax element for the NSST index.
- the decoding apparatus can determine whether the NSST can be performed, and if the NSST can be performed, the decoding apparatus can derive an NSST index for the target block.
- an NSST index indicator for a target CTU including the target block may be signaled from a bitstream, and the NSST index indicator may indicate whether NSST is enabled in the target CTU . If the value of the NSST index indicator is 1, the decoding apparatus can derive an NSST index for the target block. If the value of the NSST index indicator is 0, the decoding apparatus derives an NSST index for the target block I can not.
- the NSST index indicator may be signaled to the CTU level, or the NSST index indicator may be signaled to the CU level or other higher level, as in the example described above.
- the NSST index may be used for a plurality of components of the target block.
- the NSST index may be used for transform coefficients of a luma block of the target block, transform coefficients of a chroma Cb block, and inverse transform coefficients of a chroma Cr block.
- R + 1 th to N th transform coefficients of the luma block, R + 1 th to N th transform coefficients of the chroma Cb block, and R + 1 th to N th transforms of the chroma Cr block Coefficients can be scanned, and when the non-zero transform coefficient is included in the scanned transform coefficients, the value of the NSST index can be derived as zero.
- the NSST index may be used for transform coefficients of the luma block of the target block and the transform coefficients of the chroma Cb block.
- the (R + 1) th to Nth transform coefficients of the luma block and the (R + 1) th to Nth transform coefficients of the chroma Cb block may be scanned, If the transform coefficient is included, the value of the NSST index can be derived as zero.
- the NSST index may be used for transform coefficients of the luma block of the target block and the transform coefficients of the chroma Cr block.
- the (R + 1) th to Nth transform coefficients of the luma block and the (R + 1) th to Nth transform coefficients of the chroma Cr block may be scanned, If the transform coefficient is included, the value of the NSST index can be derived as zero.
- a range of NSST indices can be derived based on a specific condition.
- the maximum value of the NSST index may be derived based on the specific condition, and the range may be derived from 0 to the derived maximum value.
- the value of the derived NSST index may be included in the range.
- the range of the NSST index may be derived based on the size of the target block.
- the minimum width and the minimum height may be preset, and the range of the NSST index may be derived based on the width and the minimum width of the target block, the height of the target block, and the minimum height.
- the range of the NSST index can be derived based on the number of samples and the specific value of the target block. The number of samples may be a value obtained by multiplying a width of the target block by a height, and the specific value may be preset.
- the range of the NSST index may be derived based on the type of the target block. Specifically, the range of the NSST index can be derived based on whether the target block is a non-square block. Also, the range of the NSST index can be derived based on the ratio between the width and height of the target block and the specific value. The ratio between the width and height of the target block may be a value obtained by dividing the longer side of the width and height of the target block by the shorter side, and the specific value may be set in advance.
- the range of the NSST index can be derived based on the intra prediction mode of the target block. Specifically, the range of the NSST index can be derived based on whether the intra-prediction mode of the target block is a non-directional intra-prediction mode or a directional intra-prediction mode. In addition, the range of the NSST index may be derived based on whether the intra prediction mode of the target block is an intra prediction mode included in the category A (category A) or the category B (category B). Here, the intra-prediction mode included in the category A and the intra-prediction mode included in the category B may be preset.
- the category A may include a second intra prediction mode, a 10th intra prediction mode, an 18th intra prediction mode, a 26th intra prediction mode, a 34th intra prediction mode, a 42th intra prediction mode, An intra prediction mode and a 66th intra prediction mode
- the category B may include intra prediction modes other than the intra prediction mode included in the category A.
- the range of the NSST index may be derived based on information on a core transform of the target block.
- the range of the NSST index may be derived based on an AMT flag indicating whether Adaptive Multiple Core Transform (AMT) is applied.
- AMT Adaptive Multiple Core Transform
- the range of the NSST index can be derived based on the AMT horizontal flag indicating the horizontal conversion kernel and the AMT vertical flag indicating the vertical conversion kernel.
- the NSST index may indicate that the NSST is not applied to the target block.
- the decoding apparatus performs an inversed transform on the transform coefficients of the target block based on the NSST index to derive residual samples of the target block in operation S1520.
- the decoding apparatus can derive the residual samples by performing a core transform on the transform coefficients of the target block.
- the decoding apparatus may obtain an AMT flag indicating whether or not an Adaptive Multiple Core Transform (AMT) is applied from the bit stream.
- AMT Adaptive Multiple Core Transform
- the decoding apparatus can derive DCT type 2 as a transform kernel for the target block, perform inverse transform on the transform coefficients based on the DCT type 2, Samples can be derived.
- the decoding apparatus can construct a conversion subset for the horizontal conversion kernel and a conversion subset for the vertical conversion kernel, and based on the conversion index information obtained from the bitstream,
- the horizontal conversion kernel and the vertical conversion kernel can be derived, and the residual samples can be derived by performing inverse conversion on the conversion coefficients based on the horizontal conversion kernel and the vertical conversion kernel.
- the transformed subset for the horizontal transform kernel and the transformed subset for the vertically transformed kernel may include DCT type 2, DST type 7, DCT type 8, and / or DST type 1 as candidates.
- the translation index information may also include an AMT vertical flag indicating one of the candidates included in the translation subset for the horizontal translation kernel and an AMT vertical flag indicating one of the candidates included in the translation subset for the vertical translation kernel.
- the conversion kernel may be called a conversion type or a conversion core.
- the decoding apparatus calculates NSST for the transform coefficients located in the upper left target region of the target block based on the reduced transform matrix indicated by the NSST index And derive the residual samples by performing a core transformation on the target block including the modified transform coefficients.
- the size of the simplified transformation matrix may be RxN, N may be a number of samples of the upper left target region, R may be a reduced coefficient, and R may be smaller than N.
- the core transformation for the target block may be performed as follows.
- the decoding apparatus may obtain an AMT flag indicating whether or not Adaptive Multiple Core Transform (AMT) is applied from the bitstream. If the value of the AMT flag is 0, the decoding apparatus obtains DCT type 2
- the transformed kernel can be derived as the transformed kernel of the target block, and the inverse transform of the target block including the transformed transform coefficients based on the DCT type 2 can be performed to derive the residual samples.
- the decoding apparatus can construct a conversion subset for the horizontal conversion kernel and a conversion subset for the vertical conversion kernel, and based on the conversion index information obtained from the bitstream, The horizontal conversion kernel and the vertical conversion kernel can be derived and the inverse conversion can be performed on the target block including the modified conversion coefficients based on the horizontal conversion kernel and the vertical conversion kernel to derive the residual samples have.
- the transformed subset for the horizontal transform kernel and the transformed subset for the vertically transformed kernel may include DCT type 2, DST type 7, DCT type 8, and / or DST type 1 as candidates.
- the translation index information may also include an AMT vertical flag indicating one of the candidates included in the translation subset for the horizontal translation kernel and an AMT vertical flag indicating one of the candidates included in the translation subset for the vertical translation kernel.
- the conversion kernel may be called a conversion type or a conversion core.
- the decoding apparatus generates a reconstructed picture based on the residual samples (S1530).
- the decoding apparatus may generate a reconstructed picture based on the residual samples.
- the decoding apparatus may perform inter prediction or intra prediction on a target block based on prediction information received through a bitstream, derive prediction samples, and add the prediction samples and the residual samples
- the reconstructed picture can be generated. Thereafter, an in-loop filtering procedure such as deblocking filtering, SAO and / or ALF procedures may be applied to the reconstructed picture to improve subjective / objective picture quality as required, as described above.
- FIG. 16 schematically shows a decoding apparatus for performing an image decoding method according to the present invention.
- the method disclosed in Fig. 15 can be performed by the decoding apparatus disclosed in Fig.
- the entropy decoding unit of the decoding apparatus of FIG. 16 may perform S1500 to S1510 of FIG. 15
- the inverse transform unit of the decoding apparatus of FIG. 16 may perform S1520 of FIG. 15
- the adder of the decoding apparatus can perform S1530 of FIG.
- the process of deriving the prediction sample may be performed by the predicting unit of the decoding apparatus of FIG.
- the range of the NSST index can be derived based on the specific condition of the target block, thereby reducing the bit amount for the NSST index and improving the overall coding efficiency.
- the transmission of the syntax element to the NSST index can be determined based on the transform coefficients for the target block, thereby reducing the bit amount for the NSST index and improving the overall coding efficiency.
- the above-described method according to the present invention can be implemented in software, and the encoding apparatus and / or decoding apparatus according to the present invention can perform image processing of, for example, a TV, a computer, a smart phone, a set- Device.
- the above-described method may be implemented by a module (a process, a function, and the like) that performs the above-described functions.
- the module is stored in memory and can be executed by the processor.
- the memory may be internal or external to the processor and may be coupled to the processor by any of a variety of well known means.
- the processor may comprise an application-specific integrated circuit (ASIC), other chipset, logic circuitry and / or a data processing device.
- the memory may include read-only memory (ROM), random access memory (RAM), flash memory, memory cards, storage media, and / or other storage devices. That is, the embodiments described in the present invention can be implemented and executed on a processor, a microprocessor, a controller, or a chip.
- the functional units depicted in the figures may be implemented and implemented on a computer, processor, microprocessor, controller, or chip.
- the decoding apparatus and encoding apparatus to which the present invention is applied include a multimedia broadcasting transmitting and receiving apparatus, a mobile communication terminal, a home cinema video apparatus, a digital cinema video apparatus, a surveillance camera, a video chatting apparatus, (3D) video device, a video telephone video device, a medical video device, and the like, for example, a device, a storage medium, a camcorder, a video-on-demand (VoD) service providing device, an OTT video over the top video device, And may be used to process video signals or data signals.
- the OTT video (Over the top video) device may include a game console, a Blu-ray player, an Internet access TV, a home theater system, a smart phone, a tablet PC, a DVR (Digital Video Recorder)
- the processing method to which the present invention is applied may be produced in the form of a computer-executed program, and may be stored in a computer-readable recording medium.
- the multimedia data having the data structure according to the present invention can also be stored in a computer-readable recording medium.
- the computer-readable recording medium includes all kinds of storage devices and distributed storage devices in which computer-readable data is stored.
- the computer-readable recording medium may be, for example, a Blu-ray Disc (BD), a Universal Serial Bus (USB), a ROM, a PROM, an EPROM, an EEPROM, a RAM, a CD- Data storage devices.
- the computer-readable recording medium includes media implemented in the form of a carrier wave (for example, transmission over the Internet).
- bit stream generated by the encoding method can be stored in a computer-readable recording medium or transmitted over a wired or wireless communication network.
- an embodiment of the present invention may be embodied as a computer program product by program code, and the program code may be executed in a computer according to an embodiment of the present invention.
- the program code may be stored on a carrier readable by a computer.
- the content streaming system to which the present invention is applied may include an encoding server, a streaming server, a web server, a media repository, a user device, and a multimedia input device.
- the encoding server compresses content input from multimedia input devices such as a smart phone, a camera, and a camcorder into digital data to generate a bit stream and transmit the bit stream to the streaming server.
- multimedia input devices such as a smart phone, a camera, a camcorder, or the like directly generates a bitstream
- the encoding server may be omitted.
- the bitstream may be generated by an encoding method or a bitstream generating method to which the present invention is applied, and the streaming server may temporarily store the bitstream in the process of transmitting or receiving the bitstream.
- the streaming server transmits multimedia data to a user device based on a user request through the web server, and the web server serves as a medium for informing the user of what services are available.
- the web server delivers it to the streaming server, and the streaming server transmits the multimedia data to the user.
- the content streaming system may include a separate control server. In this case, the control server controls commands / responses among the devices in the content streaming system.
- the streaming server may receive content from a media repository and / or an encoding server. For example, when receiving the content from the encoding server, the content can be received in real time. In this case, in order to provide a smooth streaming service, the streaming server can store the bit stream for a predetermined time.
- Examples of the user device include a mobile phone, a smart phone, a laptop computer, a digital broadcasting terminal, a personal digital assistant (PDA), a portable multimedia player (PMP), a navigation device, a slate PC, Such as tablet PCs, ultrabooks, wearable devices (e.g., smartwatches, smart glass, HMDs (head mounted displays)), digital TVs, desktops Computers, and digital signage.
- PDA personal digital assistant
- PMP portable multimedia player
- slate PC Such as tablet PCs, ultrabooks, wearable devices (e.g., smartwatches, smart glass, HMDs (head mounted displays)), digital TVs, desktops Computers, and digital signage.
- Each of the servers in the content streaming system can be operated as a distributed server. In this case, data received at each server can be distributed.
Abstract
Description
Claims (15)
- 디코딩 장치에 의하여 수행되는 영상 디코딩 방법에 있어서,비트스트림으로부터 대상 블록의 변환 계수들을 도출하는 단계;상기 대상 블록에 대한 NSST(Non-Separable Secondary Transform) 인덱스를 도출하는 단계;상기 NSST 인덱스를 기반으로 상기 대상 블록의 상기 변환 계수들에 대한 역변환(inversed transform)을 수행하여 상기 대상 블록의 레지듀얼 샘플들을 도출하는 단계; 및상기 레지듀얼 샘플들을 기반으로 복원 픽처를 생성하는 단계를 포함하는 것을 특징으로 하는 영상 디코딩 방법.
- 제1항에 있어서,상기 NSST 인덱스를 기반으로 상기 대상 블록의 상기 변환 계수들에 대한 역변환(inversed transform)를 수행하여 상기 대상 블록의 상기 레지듀얼 샘플들을 도출하는 단계는,상기 NSST 인덱스의 값이 0인 경우, 상기 대상 블록의 상기 변환 계수들에 대한 핵심 변환(core transform)을 수행하여 상기 레지듀얼 샘플들을 도출하는 단계; 및상기 NSST 인덱스의 값이 0이 아닌 경우, 상기 NSST 인덱스가 가리키는 간소화 변환 매트릭스(reduced transform matrix)를 기반으로 상기 대상 블록의 좌상단 대상 영역에 위치하는 변환 계수들에 대한 NSST 를 수행하여 수정된 변환 계수들을 도출하고, 상기 수정된 변환 계수들을 포함하는 상기 대상 블록에 대한 핵심 변환을 수행하여 상기 레지듀얼 샘플들을 도출하는 단계를 포함하는 것을 특징으로 하는 영상 디코딩 방법.
- 제2항에 있어서,상기 간소화 변환 매트릭스의 사이즈는 RxN 이고,상기 N은 상기 좌상단 대상 영역의 샘플수이고, 상기 R은 간소화 계수(reduced coefficient)이고, 상기 R은 상기 N 보다 작은 것을 특징으로 하는 영상 디코딩 방법.
- 제3항에 있어서,상기 대상 블록에 대한 상기 NSST 인덱스를 도출하는 단계는,상기 대상 블록의 변환 계수들 중 R+1번째부터 N번째의 변환 계수들을 스캔하는 단계; 및상기 R+1번째부터 N번째의 변환 계수들에 0이 아닌 변환 계수가 포함된 경우, 상기 NSST 인덱스의 값을 0으로 도출하는 단계를 포함하는 영상 디코딩 방법.
- 제3항에 있어서,상기 대상 블록에 대한 상기 NSST 인덱스를 도출하는 단계는,상기 R+1번째부터 N번째의 변환 계수들에 0이 아닌 변환 계수가 포함되지 않은 경우, 상기 비트스트림에 포함된 상기 NSST 인덱스에 대한 신텍스 요소(syntax element)를 파싱하여 상기 NSST 인덱스의 값을 도출하는 단계를 더 포함하는 것을 특징으로 하는 영상 디코딩 방법.
- 상기 제1항에 있어서,상기 대상 블록의 폭 및 최소 폭, 상기 대상 블록의 높이 및 최소 높이를 기반으로 상기 NSST 인덱스의 범위가 도출되고,상기 최소 폭 및 상기 최소 높이는 기설정되는 것을 특징으로 하는 영상 디코딩 방법.
- 제1항에 있어서,상기 대상 블록의 샘플수 및 특정값을 기반으로 상기 NSST 인덱스의 범위가 도출되고,상기 샘플수는 상기 대상 블록의 폭과 높이를 곱한 값이고, 상기 특정값은 기설정되는 것을 특징으로 하는 영상 디코딩 방법.
- 제1항에 있어서,상기 대상 블록이 비정방형(non-square) 블록인지 여부를 기반으로 상기 NSST 인덱스의 범위가 도출되는 것을 특징으로 하는 영상 디코딩 방법.
- 제3항에 있어서,상기 NSST 인덱스가 상기 대상 블록의 루마 블록의 변환 계수들, 크로마 Cb 블록의 변환 계수들 및 크로마 Cr 블록의 변환 계수들에 대한 역변환에 사용되는 경우, 상기 루마 블록의 R+1번째부터 N번째의 변환 계수들, 상기 크로마 Cb 블록의 R+1번째부터 N번째의 변환 계수들 및 상기 크로마 Cr 블록의 R+1번째부터 N번째의 변환 계수들이 스캔되고,상기 스캔된 변환 계수들에 0이 아닌 변환 계수가 포함된 경우, 상기 NSST 인덱스의 값은 0으로 도출되는 것을 특징으로 하는 영상 디코딩 방법.
- 제1항에 있어서,비트스트림으로부터 상기 대상 블록을 포함하는 대상 CTU 에 대한 NSST 인덱스 인디케이터(indicator)가 시그널링되고,상기 NSST 인덱스 인디케이터는 상기 대상 CTU 에 NSST 가 가용한지(enabled) 여부를 나타내는 것을 특징으로 하는 영상 디코딩 방법.
- 영상 디코딩 장치에 있어서,비트스트림으로부터 대상 블록의 변환 계수들을 도출하고, 상기 대상 블록에 대한 NSST(Non-Separable Secondary Transform) 인덱스를 도출하는 엔트로피 디코딩부;상기 NSST 인덱스를 기반으로 상기 대상 블록의 상기 변환 계수들에 대한 역변환(inversed transform)을 수행하여 상기 대상 블록의 레지듀얼 샘플들을 도출하는 역변환부; 및상기 레지듀얼 샘플들을 기반으로 복원 픽처를 생성하는 가산부를 포함하는 것을 특징으로 하는 영상 디코딩 장치.
- 인코딩 장치에 의하여 수행되는 영상 인코딩 방법에 있어서,대상 블록의 레지듀얼 샘플들을 도출하는 단계;상기 레지듀얼 샘플들에 대한 변환(transform)을 수행하여 상기 대상 블록의 변환 계수들을 도출하는 단계;상기 대상 블록에 대한 NSST 인덱스의 인코딩 여부를 결정하는 단계; 및상기 변환 계수들에 대한 정보를 인코딩하는 단계를 포함하되,상기 NSST 인덱스의 인코딩 여부를 결정하는 단계는,상기 대상 블록의 상기 변환 계수들 중 R+1번째부터 N번째의 변환 계수들을 스캔하는 단계; 및상기 R+1번째부터 N번째의 변환 계수들에 0이 아닌 변환 계수가 포함된 경우, 상기 NSST 인덱스를 인코딩하지 않는 것으로 결정하는 단계를 포함하고,상기 N은 상기 대상 블록의 좌상단 대상 영역의 샘플수이고, 상기 R은 간소화 계수(reduced coefficient)이고, 상기 R은 상기 N 보다 작은 것을 특징으로 하는 영상 인코딩 방법.
- 제12항에 있어서,상기 NSST 인덱스의 인코딩 여부를 결정하는 단계는,상기 R+1번째부터 N번째의 변환 계수들에 0이 아닌 변환 계수가 포함되지 않은 경우, 상기 NSST 인덱스를 인코딩하는 것으로 결정하는 단계를 더 포함하고,상기 R+1번째부터 N번째의 변환 계수들에 0이 아닌 변환 계수가 포함되지 않은 경우, 상기 변환 계수들에 대한 정보는 상기 NSST 인덱스에 대한 신텍스 요소(syntax element)를 포함하는 것을 특징으로 하는 영상 인코딩 방법.
- 제12항에 있어서,상기 레지듀얼 샘플들에 대한 변환을 수행하여 상기 대상 블록의 상기 변환 계수들을 도출하는 단계는,상기 대상 블록에 대한 NSST 적용 여부를 결정하는 단계;상기 대상 블록에 대하여 상기 NSST 가 적용되는 경우, 상기 레지듀얼 샘플들에 대한 핵심 변환을 수행하여 수정된 변환 계수들을 도출하고, 간소화 변환 매트릭스를 기반으로 상기 좌상단 대상 영역에 위치하는 수정된 변환 계수들에 대한 NSST 를 수행하여 상기 대상 블록의 상기 변환 계수들을 도출하는 단계; 및상기 대상 블록에 대하여 상기 NSST 가 적용되지 않는 경우, 상기 레지듀얼 샘플들에 대한 핵심 변환을 수행하여 상기 대상 블록의 상기 변환 계수들을 도출하는 단계를 포함하는 것을 특징으로 하는 영상 인코딩 방법.
- 제12항에 있어서,상기 대상 블록의 폭 및 최소 폭, 상기 대상 블록의 높이 및 최소 높이를 기반으로 상기 NSST 인덱스의 범위가 도출되고,상기 최소 폭 및 상기 최소 높이는 기설정되는 것을 특징으로 하는 영상 인코딩 방법.
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