WO2018128228A1 - Procédé et dispositif de décodage d'image dans un système de codage d'image - Google Patents

Procédé et dispositif de décodage d'image dans un système de codage d'image Download PDF

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WO2018128228A1
WO2018128228A1 PCT/KR2017/005671 KR2017005671W WO2018128228A1 WO 2018128228 A1 WO2018128228 A1 WO 2018128228A1 KR 2017005671 W KR2017005671 W KR 2017005671W WO 2018128228 A1 WO2018128228 A1 WO 2018128228A1
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index
reference picture
mvpl0
mvpl1
motion information
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PCT/KR2017/005671
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English (en)
Korean (ko)
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남정학
박내리
서정동
임재현
장형문
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엘지전자 주식회사
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
    • H04N19/102—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the element, parameter or selection affected or controlled by the adaptive coding
    • H04N19/103—Selection of coding mode or of prediction mode
    • H04N19/105—Selection of the reference unit for prediction within a chosen coding or prediction mode, e.g. adaptive choice of position and number of pixels used for prediction
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
    • H04N19/134—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the element, parameter or criterion affecting or controlling the adaptive coding
    • H04N19/136—Incoming video signal characteristics or properties
    • H04N19/137—Motion inside a coding unit, e.g. average field, frame or block difference
    • H04N19/139—Analysis of motion vectors, e.g. their magnitude, direction, variance or reliability
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
    • H04N19/169—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding
    • H04N19/17—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding the unit being an image region, e.g. an object
    • H04N19/176—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding the unit being an image region, e.g. an object the region being a block, e.g. a macroblock
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/70—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals characterised by syntax aspects related to video coding, e.g. related to compression standards

Definitions

  • the present invention relates to an image coding technique, and more particularly, to an image decoding method and apparatus in an image coding system.
  • the demand for high resolution and high quality images such as high definition (HD) images and ultra high definition (UHD) images is increasing in various fields.
  • the higher the resolution and the higher quality of the image data the more information or bit rate is transmitted than the existing image data. Therefore, the image data can be transmitted by using a medium such as a conventional wired / wireless broadband line or by using a conventional storage medium. In the case of storage, the transmission cost and the storage cost are increased.
  • a high efficiency image compression technique is required to effectively transmit, store, and reproduce high resolution, high quality image information.
  • An object of the present invention is to provide a method and apparatus for improving image coding efficiency.
  • Another object of the present invention is to provide an inter prediction method and apparatus for receiving a syntax element representing L0 motion information and L1 motion information for a current block.
  • Another technical problem of the present invention is to provide an inter prediction method and apparatus for receiving an index indicating a first reference picture and a second reference picture of a current block.
  • Another technical problem of the present invention is to provide an inter prediction method and apparatus for receiving an index indicating an MVPL0 and an MVPL1 of a current block.
  • Another object of the present invention is to provide an inter prediction method and apparatus for receiving an index indicating a first reference picture, a second reference picture, MVPL0, and MVPL1 of a current block.
  • an image decoding method performed by a decoding apparatus.
  • the method includes deriving a reference picture list 0 (List 0, L0) and a reference picture list 1 (List 1, L1), and a syntax element representing L0 motion information and L1 motion information for the current block through a bitstream. an element), deriving the L0 motion information and the L1 motion information for the current block based on the syntax element, and predicting the current block based on the L0 motion information and the L1 motion information.
  • the L0 motion information comprises at least one of an index of a first reference picture of the current block included in the L0 and a motion vector predictor L0 (MVL0).
  • the L1 motion information includes an index of a second reference picture of the current block included in the L1 and a motion vector predictor L1 (MVL1). It characterized in that it comprises at least one of.
  • a decoding apparatus for performing image decoding.
  • the decoding apparatus may include an entropy decoding unit configured to receive a syntax element indicating L0 motion information and L1 motion information for a current block through a bitstream, a reference picture list 0 (List 0, L0), and a reference picture list 1.
  • Derive (List 1, L1), derive the L0 motion information and the L1 motion information for the current block based on the syntax element, and determine the current block based on the L0 motion information and the L1 motion information.
  • a prediction unit for generating a prediction sample wherein the L0 motion information includes at least one of a first reference picture of a current block included in the L0 and a motion vector predictor L0 (MVL0);
  • the L1 motion information includes at least one of a second reference picture and a motion vector predictor L1 (MVL1) of the current block included in the L1. Characterized by including one.
  • a video encoding method performed by an encoding apparatus includes deriving a reference picture list 0 (List 0, L0) and a reference picture list 1 (List 1, L1), deriving L0 motion information and L1 motion information for a current block, the L0 motion information, and Generating a prediction sample of the current block based on the L1 motion information, generating a syntax element representing the L0 motion information and the L1 motion information for the current block, and the L0 motion for the current block Encoding and outputting the syntax element representing the information and the L1 motion information, wherein the L0 motion information includes a first reference picture and a motion vector predictor L0 of the current block included in the L0. , MVPL0), and the L1 motion information includes a second reference picture and a motion vector of the current block included in the L1. And a predictor L1 (Motion Vector Predictor L1, MVPL1).
  • a video encoding apparatus derives reference picture list 0 (List 0, L0) and reference picture list 1 (List 1, L1), derives L0 motion information and L1 motion information for the current block, and extracts the L0 motion information and the A prediction unit generating a prediction sample of the current block based on L1 motion information, generating a syntax element representing the L0 motion information and the L1 motion information for the current block, and the L0 motion information for the current block And an entropy encoding unit for encoding and outputting the syntax element representing the L1 motion information, wherein the L0 motion information includes a first reference picture and a motion vector predictor L0 of the current block included in the L0. , MVPL0), and the L1 motion information includes a second reference picture of the current block included in the L1; Jikim vector predictors characterized in that it includes at least one of L1 (Motion Vector Predictor L1, MVPL1).
  • the L0 motion information and the L1 motion information of the current block can be derived. Coding efficiency can be improved.
  • the present invention by receiving a syntax element representing the L0 motion information and the L1 motion information for the current block, it is possible to reduce the data amount of information for inter prediction of the current block, thereby improving overall coding efficiency.
  • information indicating whether the syntax element indicating the L0 motion information and the L1 motion information for the current block is used can be selectively applied to a part of the image, thereby improving the overall coding efficiency.
  • FIG. 1 is a diagram schematically illustrating a configuration of a video encoding apparatus to which the present invention may be applied.
  • FIG. 2 is a diagram schematically illustrating a configuration of a video decoding apparatus to which the present invention may be applied.
  • FIG. 3 exemplarily shows reference pictures included in a decoded picture buffer (DPB) and a reference picture list for inter prediction.
  • DPB decoded picture buffer
  • FIG. 4 illustrates a motion picture L0 and a motion vector L1 and a first reference picture and a second reference picture for inter prediction of the current block.
  • FIG. 5 schematically illustrates a video encoding method by an encoding device according to the present invention.
  • FIG. 6 schematically illustrates a video decoding method by a decoding apparatus according to the present invention.
  • each configuration in the drawings described in the present invention are shown independently for the convenience of description of the different characteristic functions, it does not mean that each configuration is implemented by separate hardware or separate software.
  • two or more of each configuration may be combined to form one configuration, or one configuration may be divided into a plurality of configurations.
  • Embodiments in which each configuration is integrated and / or separated are also included in the scope of the present invention without departing from the spirit of the present invention.
  • a picture generally refers to a unit representing one image of a specific time zone
  • a slice is a unit constituting a part of a picture in coding.
  • One picture may be composed of a plurality of slices, and if necessary, the picture and the slice may be mixed with each other.
  • a pixel or a pel may refer to a minimum unit constituting one picture (or image). Also, 'sample' may be used as a term corresponding to a pixel.
  • a sample may generally represent a pixel or a value of a pixel, and may only represent pixel / pixel values of the luma component, or only pixel / pixel values of the chroma component.
  • a unit represents the basic unit of image processing.
  • the unit may include at least one of a specific region of the picture and information related to the region.
  • the unit may be used interchangeably with terms such as block or area in some cases.
  • an M ⁇ N block may represent a set of samples or transform coefficients composed of M columns and N rows.
  • FIG. 1 is a diagram schematically illustrating a configuration of a video encoding apparatus to which the present invention may be applied.
  • the video encoding apparatus 100 may include a picture divider 105, a predictor 110, a subtractor 115, a transformer 120, a quantizer 125, a reordering unit 130, An entropy encoding unit 135, an inverse quantization unit 140, an inverse transform unit 145, an adder 150, a filter unit 155, and a memory 160 are included.
  • the picture divider 105 may divide the input picture into at least one processing unit.
  • the processing unit may be a coding unit (CU), a prediction unit (PU), or a transform unit (TU).
  • a coding unit is a unit block of coding and may be split from a largest coding unit (LCU) into coding units of a deeper depth along a quad-tree structure.
  • LCU largest coding unit
  • the maximum coding unit may be used as the final coding unit immediately based on coding efficiency according to the image characteristic, or if necessary, the coding unit is recursively divided into coding units of lower depths and optimized.
  • a coding unit of size may be used as the final coding unit.
  • the coding unit may not be split into smaller coding units than the minimum coding unit.
  • the final coding unit refers to a coding unit that is the basis of partitioning or partitioning into a prediction unit or a transform unit.
  • the prediction unit is a block partitioning from the coding unit block and may be a unit block of sample prediction. In this case, the prediction unit may be divided into sub blocks.
  • the transform unit may be divided along the quad tree structure from the coding unit block, and may be a unit block for deriving a transform coefficient and / or a unit block for deriving a residual signal from the transform coefficient.
  • a coding unit may be called a coding block (CB)
  • a prediction unit is a prediction block (PB)
  • a transform unit may be called a transform block (TB).
  • a prediction block or prediction unit may mean a specific area in the form of a block within a picture, and may include an array of prediction samples.
  • a transform block or a transform unit may mean a specific area in a block form within a picture, and may include an array of transform coefficients or residual samples.
  • the prediction unit 110 may perform a prediction on a block to be processed (hereinafter, referred to as a current block) and generate a prediction block including prediction samples of the current block.
  • the unit of prediction performed by 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. As an example, the prediction unit 110 may determine whether intra prediction or inter prediction is applied on a CU basis.
  • the prediction unit 110 may derive a prediction sample for the current block based on reference samples outside the current block in the picture to which the current block belongs (hereinafter, referred to as the current picture). In this case, the prediction unit 110 may (i) derive the prediction sample based on the average or interpolation of neighboring reference samples of the current block, and (ii) the neighbor reference of the current block.
  • the prediction sample may be derived based on a reference sample present in a specific (prediction) direction with respect to the prediction sample among the samples. In case of (i), it may be called non-directional mode or non-angle mode, and in case of (ii), it may be called directional mode or 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 planner mode (Planar mode).
  • the prediction unit 110 may determine the prediction mode applied to the current block by using the prediction mode applied to the neighboring block.
  • the prediction unit 110 may derive the prediction sample for the current block based on the sample specified by the motion vector on the reference picture.
  • the prediction unit 110 may apply one of a skip mode, a merge mode, and a motion vector prediction (MVP) mode to derive a prediction sample for the current block.
  • the prediction unit 110 may use the motion information of the neighboring block as the motion information of the current block.
  • the skip mode unlike the merge mode, the difference (residual) between the prediction sample and the original sample is not transmitted.
  • the MVP mode the motion vector of the current block may be derived using the motion vector of the neighboring block as a motion vector predictor.
  • the neighboring block may include a spatial neighboring block existing in the current picture and a temporal neighboring block present in the reference picture.
  • a reference picture including the temporal neighboring block may be called 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 encoded (entropy) and output in the form of a bitstream.
  • the highest picture on the reference picture list may be used as the reference picture.
  • Reference pictures included in a reference picture list may be sorted based on a difference in a picture order count (POC) between a current picture and a corresponding reference picture.
  • POC picture order count
  • the subtraction unit 115 generates a residual sample which is a difference between the original sample and the prediction sample.
  • residual samples may not be generated as described above.
  • the transform unit 120 generates a transform coefficient by transforming the residual sample in units of transform blocks.
  • the transform unit 120 may perform the transformation according to the size of the transform block and the prediction mode applied to the coding block or the prediction block that spatially overlaps the transform block. For example, if intra prediction is applied to the coding block or the prediction block that overlaps the transform block, and the transform block is a 4 ⁇ 4 residual array, the residual sample uses a discrete sine transform (DST). In other cases, the residual sample may be transformed by using a discrete cosine transform (DCT).
  • DST discrete sine transform
  • DCT discrete cosine transform
  • the quantization unit 125 may quantize the transform coefficients to generate quantized transform coefficients.
  • the reordering unit 130 rearranges the quantized transform coefficients.
  • the reordering unit 130 may reorder the quantized transform coefficients in the form of a block into a one-dimensional vector form through a coefficient scanning method. Although the reordering unit 130 has been described in a separate configuration, the reordering unit 130 may be part of the quantization unit 125.
  • the entropy encoding unit 135 may perform entropy encoding on the quantized transform coefficients.
  • Entropy encoding may include, for example, encoding methods such as exponential Golomb, context-adaptive variable length coding (CAVLC), context-adaptive binary arithmetic coding (CABAC), and the like.
  • the entropy encoding unit 135 may encode information necessary for video reconstruction other than the quantized transform coefficients (for example, a value of a syntax element) together or separately. Entropy encoded information may be transmitted or stored in units of network abstraction layer (NAL) units in the form of bitstreams.
  • NAL network abstraction layer
  • the inverse quantization unit 140 inverse quantizes the quantized values (quantized transform coefficients) in the quantization unit 125, and the inverse transform unit 145 inversely transforms the inverse quantized values in the inverse quantization unit 135 to obtain a residual sample.
  • the adder 150 reconstructs the picture by combining the residual sample and the predictive sample.
  • the residual sample and the predictive sample may be added in units of blocks to generate a reconstructed block.
  • the adder 150 has been described in a separate configuration, the adder 150 may be part of the predictor 110.
  • the filter unit 155 may apply a deblocking filter and / or a sample adaptive offset to the reconstructed picture. Through deblocking filtering and / or sample adaptive offset, the artifacts of the block boundaries in the reconstructed picture or the distortion in the quantization process can be corrected.
  • the sample adaptive offset may be applied on a sample basis and may be applied after the process of deblocking filtering is completed.
  • the filter unit 155 may apply an adaptive loop filter (ALF) to the reconstructed picture. ALF may be applied to the reconstructed picture after the deblocking filter and / or sample adaptive offset is applied.
  • ALF adaptive loop filter
  • the memory 160 may store information necessary for reconstruction picture or encoding / decoding.
  • the reconstructed picture may be a reconstructed picture after the filtering process is completed by the filter unit 155.
  • the stored reconstructed 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.
  • pictures used for inter prediction may be designated by a reference picture set or a reference picture list.
  • FIG. 2 is a diagram schematically illustrating a configuration of a video decoding apparatus to which the present invention may be applied.
  • the video decoding apparatus 200 includes an entropy decoding unit 210, a reordering unit 220, an inverse quantization unit 230, an inverse transform unit 240, a predictor 250, and an adder 260. , A filter unit 270, and a memory 280.
  • the video decoding apparatus 200 may reconstruct the video in response to a process in which the video information is processed in the video encoding apparatus.
  • the video decoding apparatus 200 may perform video decoding using a processing unit applied in the video encoding apparatus.
  • the processing unit block of video decoding may be a coding unit block, a prediction unit block, or a transform unit block.
  • the coding unit block may be divided along the quad tree structure from the largest coding unit block as a unit block of decoding.
  • the prediction unit block is a block partitioned from the coding unit block and may be a unit block of sample prediction. In this case, the prediction unit block may be divided into sub blocks.
  • the transform unit block may be divided along the quad tree structure from the coding unit block, and may be a unit block for deriving a transform coefficient or a unit block for deriving a residual signal from the transform coefficient.
  • the entropy decoding unit 210 may parse the bitstream and output information necessary for video reconstruction or picture reconstruction. For example, the entropy decoding unit 210 decodes information in a bitstream based on a coding method such as exponential Golomb coding, CAVLC, or CABAC, quantized values of syntax elements necessary for video reconstruction, and residual coefficients. Can be output.
  • a coding method such as exponential Golomb coding, CAVLC, or CABAC, quantized values of syntax elements necessary for video reconstruction, and residual coefficients. Can be output.
  • the CABAC entropy decoding method receives a bin corresponding to each syntax element in a bitstream, and decodes syntax element information and decoding information of neighboring and decoding target blocks or information of symbols / bins decoded in a previous step.
  • the context model may be determined using the context model, the probability of occurrence of a bin may be predicted according to the determined context model, and arithmetic decoding of the bin may be performed to generate a symbol corresponding to the value of each syntax element. have.
  • the CABAC entropy decoding method may update the context model by using the information of the decoded symbol / bin for the context model of the next symbol / bean after determining the context model.
  • the information related to the prediction among the information decoded by the entropy decoding unit 210 is provided to the prediction unit 230, and the residual value on which the entropy decoding has been performed by the entropy decoding unit 210, that is, the quantized transform coefficient, is used as a reordering unit ( 220).
  • the reordering unit 220 may rearrange the quantized transform coefficients in the form of a two-dimensional block.
  • the reordering unit 220 may perform reordering in response to coefficient scanning performed by the encoding apparatus. Although the reordering unit 220 has been described in a separate configuration, the reordering unit 220 may be a part of the quantization unit 230.
  • the inverse quantization unit 230 may output the transform coefficients by inversely quantizing the transform coefficients quantized based on the (inverse) quantization parameter.
  • information for deriving a quantization parameter may be signaled from the encoding apparatus.
  • the inverse transform unit 240 may induce residual samples by inversely transforming the transform coefficients.
  • the prediction unit 250 may perform prediction on the current block and generate a prediction block including prediction samples for the current block.
  • the unit of prediction performed by the prediction unit 250 may be a coding block, a transform block, or a prediction block.
  • the prediction unit 250 may determine whether to apply intra prediction or inter prediction based on the information about the prediction.
  • a unit for determining which of intra prediction and inter prediction is to be applied and a unit for generating a prediction sample may be different.
  • the unit for generating a prediction sample in inter prediction and intra prediction may also be different.
  • whether to apply inter prediction or intra prediction may be determined in units of CUs.
  • a prediction mode may be determined and a prediction sample may be generated in PU units
  • intra prediction a prediction mode may be determined in PU units and a prediction sample may be generated in TU units.
  • the prediction unit 250 may derive the prediction sample for the current block based on the neighbor reference samples in the current picture.
  • the prediction unit 250 may derive the prediction sample for the current block by applying the directional mode or the non-directional mode based on the neighbor reference samples of the current block.
  • the prediction mode to be applied to the current block may be determined using the intra prediction mode of the neighboring block.
  • the prediction unit 250 may derive the prediction sample for the current block based on the sample specified on the reference picture by the motion vector on the reference picture.
  • the prediction unit 250 may induce a prediction sample for the current block by applying any one of a skip mode, a merge mode, and an MVP mode.
  • motion information required for inter prediction of the current block provided by the video encoding apparatus for example, information about a motion vector, a reference picture index, and the like may be obtained or derived based on the prediction information.
  • the motion information of the neighboring block may be used as the motion information of the current block.
  • the neighboring block may include a spatial neighboring block and a temporal neighboring block.
  • the predictor 250 may construct a merge candidate list using motion information of available neighboring blocks, and may use information indicated by the merge index on the merge candidate list as a 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 the temporal neighboring block is used in the skip mode and the merge mode, the highest picture on the reference picture list may be used as the reference picture.
  • the difference (residual) between the prediction sample and the original sample is not transmitted.
  • the motion vector of the current block may be derived using the motion vector of the 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 by using a motion vector of a reconstructed spatial neighboring block and / or a motion vector corresponding to a Col block, which is a temporal neighboring block.
  • the motion vector of the candidate block selected from the merge candidate list is used as the motion vector of the current block.
  • the information about the prediction may include a merge index indicating a candidate block having an optimal motion vector selected from candidate blocks included in the merge candidate list.
  • the prediction unit 250 may derive the motion vector of the current block by using the merge index.
  • a motion vector predictor candidate list may be generated using a motion vector of a reconstructed spatial neighboring block and / or a motion vector corresponding to a Col block which is a temporal neighboring block.
  • the prediction information may include a prediction motion vector index indicating an optimal motion vector selected from the motion vector candidates included in the list.
  • the prediction unit 250 may select the predicted motion vector of the current block from the motion vector candidates included in the motion vector candidate list using the motion vector index.
  • the prediction unit of the encoding apparatus may obtain a motion vector difference (MVD) between the motion vector of the current block and the motion vector predictor, and may encode the output vector in a bitstream form. That is, MVD may be obtained by subtracting the motion vector predictor from the motion vector of the current block.
  • the prediction unit 250 may obtain a motion vector difference included in the information about the prediction, and derive the motion vector of the current block by adding the motion vector difference and the motion vector predictor.
  • the prediction unit may also obtain or derive a reference picture index or the like indicating a reference picture from the information about the prediction.
  • the adder 260 may reconstruct the current block or the current picture by adding the residual sample and the predictive sample.
  • the adder 260 may reconstruct the current picture by adding the residual sample and the predictive sample in block units. Since the residual is not transmitted when the skip mode is applied, the prediction sample may be a reconstruction sample.
  • the adder 260 is described in a separate configuration, the adder 260 may be part of the predictor 250.
  • the filter unit 270 may apply the deblocking filtering sample adaptive offset, and / or ALF to the reconstructed picture.
  • the sample adaptive offset may be applied in units of samples and may be applied after deblocking filtering.
  • ALF may be applied after deblocking filtering and / or sample adaptive offset.
  • the memory 280 may store information necessary for reconstruction picture or decoding.
  • the reconstructed picture may be a reconstructed picture after the filtering process is completed by the filter unit 270.
  • the memory 280 may store pictures used for inter prediction.
  • 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 280 may output the reconstructed picture in an output order.
  • reference picture list 0 or reference picture list 1 may be configured based on decoded pictures for prediction on the current block, or both reference picture lists 0 and 1 may be configured.
  • a decoded picture buffer DPB
  • a reference picture list for inter prediction a decoded picture buffer
  • POC picture order count
  • the POC corresponds to the display order of the pictures and may be distinguished from the coding order.
  • Various numbers of reference pictures may be used to construct the reference picture list 0 or the reference picture list 1 according to DPB sizes allowed by the decoding apparatus.
  • the reference picture list 0 may be called L0 (List 0), and the reference picture list 1 may be called L1 (List 1).
  • the reference pictures included in the L0 and the L1 may be arranged based on a difference in picture order count (POC) between the current picture and the reference picture.
  • B slice the slice type of the slice including the current block
  • P slice P slice
  • the L0 motion information may include at least one of an index (refidxL0) and an associated motion vector (Motion Vector L0, MVL0) of a reference picture included in the L0 with respect to the current block.
  • the L0 motion information may include at least one of an index of a reference picture included in the L0 and an associated motion vector predictor L0 (MVL0) for the current block.
  • the L1 motion information may include at least one of an index (refidxL1) and an associated motion vector (Motion Vector L1, MVL1) of a reference picture included in the L1 with respect to the current block.
  • the L1 motion information may include at least one of an index of a reference picture of the current block included in the L1 and a motion vector predictor L1 (MVL1) associated with the reference picture.
  • the reference picture of the current block included in the L0 may be referred to as a first reference picture, and the reference picture of the current block included in the L1 may be referred to as a second reference picture.
  • Information on the motion vector difference L0 (MVDL0) for the MVPL0 and information on the motion vector difference L1 (MVDL1) for the MVPL1 may be received, and the MVPL0 and the MVDL0 may be received.
  • a motion vector L0 (MVL0) associated with the first reference picture may be derived, and a motion vector L1 (Motion Vector L1, MVL1 associated with the second reference picture based on the MVPL1 and the MVDL1) may be derived. ) Can be derived.
  • Pair prediction of the current block may be performed based on the first reference picture, the MVL0 and the second reference picture, and the MVL1, and a prediction sample of the current block may be derived.
  • a prediction sample of the current block may be derived.
  • an L0 prediction sample may be obtained based on the first reference picture and the MVL0
  • an L1 prediction sample may be obtained based on the second reference picture and the MVL1 and weighted by the L0 prediction sample and the L1 prediction sample.
  • the prediction sample of the current block may be derived through a weighted sum.
  • the MVPL0 candidate list and the MVPL1 candidate list may be derived based on motion vectors of neighboring blocks of the current block.
  • the MVPL0 candidate list may be configured by using motion vectors of neighboring blocks of the current block as MVPL0 candidates
  • the MVPL1 candidate list may be configured by using motion vectors of neighboring blocks of the current block as MVPL1 candidates.
  • a syntax element representing the L0 motion information of the current block and a syntax element representing the L1 motion information may be received.
  • the syntax element indicating the L0 motion information may be received.
  • the syntax element indicating the L1 motion information may be received.
  • the syntax element representing the L0 motion information may indicate an index indicating the first reference picture among the reference pictures included in the L0, or the syntax element indicating the L0 motion information may be an MVPL0 candidate included in the MVPL0 candidate list.
  • the flag indicating the MVPL0 may be indicated.
  • the syntax element indicating the L1 motion information may indicate an index indicating the second reference picture among the reference pictures included in the L1, or the syntax element indicating the L1 motion information is included in the MVPL1 candidate list.
  • a flag indicating the MVPL1 may be indicated.
  • a syntax structure including a syntax element representing the L0 motion information and a syntax element representing the L1 motion information may be represented as shown in the following table.
  • x0 and y0 indicate the position (x0, y0) of the top-left sample of the current block
  • inter_pred_idc indicates whether the prediction performed on the current block is L0 prediction, L1 prediction, or pair prediction.
  • a syntax element indicating a ref_idx_l0 is a syntax element indicating the first reference picture among the reference pictures included in the L0
  • ref_idx_l1 is a syntax element indicating the second reference picture among the reference pictures included in the L1
  • mvp_l0_flag is the Among the MVPL0 candidates included in the MVPL0 candidate list
  • a syntax element indicating the MVPL0, mvp_l1_flag indicates a syntax element indicating the MVPL1 among the MVPL1 candidates included in the MVPL1 candidate list
  • mvd_coding indicates a syntax element indicating the MVDL0 and / or the MVDL1.
  • the ref_idx_l0 may be transmitted (signaled) when the L0 prediction or the pair prediction is performed on the current block, and the ref_idx_l1 may be transmitted when the L1 prediction or the pair prediction is performed on the current block.
  • the mvp_l0_flag may be transmitted when the L0 prediction or the pair prediction is performed on the current block
  • the mvp_l1_flag may be transmitted when the L1 prediction or the pair prediction is performed on the current block.
  • the mvd_coding may include the MVDL0 and / or the MVDL1, and each MVD may be composed of x and y components, and the code and size of each component may be transmitted separately.
  • the inter_pred_idc may indicate which prediction among the L0 prediction, the L1 prediction, and the pair prediction corresponds to the prediction performed on the current block.
  • the value of the inter_pred_idc may represent the L0 prediction, the L1 prediction, or the pair prediction.
  • the prediction of the value of inter_pred_idc may be defined as shown in the following table.
  • inter_pred_idc is an inter prediction index indicating which prediction is performed on the current block, L0 prediction, L1 prediction, or pair prediction
  • PRED_L0 is the L0 prediction
  • PRED_L1 is the L1 prediction
  • PRED_BI is the pair prediction.
  • a syntax element representing the L0 motion information and a syntax element representing the L1 motion information are not transmitted, respectively, and both L0 motion information and the L1 motion information are transmitted.
  • a syntax element indicating a may be transmitted.
  • an index indicating both the first reference picture and the second reference picture may be transmitted. That is, the first reference picture and the second reference picture may be derived based on the index.
  • a reference picture indicated by the index among the reference pictures of L0 may be derived as the first reference picture
  • a reference picture indicated by the index among the reference pictures of L1 may be derived as the second reference picture.
  • the L0 motion information may include an index of the first reference picture
  • the L1 motion information may include an index of the second reference picture
  • both the L0 motion information and the L1 motion information may be included.
  • the representing syntax element may indicate the index indicating the first reference picture and the second reference picture.
  • the index indicating the first reference picture and the second reference picture may be referred to as a first index.
  • a syntax structure including a syntax element representing the first index representing both the L0 motion information and the L1 motion information may be represented as in the following table.
  • x0 and y0 indicate the position (x0, y0) of the top-left sample of the current block
  • inter_pred_idc indicates whether the prediction performed on the current block is L0 prediction, L1 prediction, or pair prediction.
  • a syntax element indicating a ref_idx_l0 is a syntax element indicating the first reference picture among the reference pictures included in the L0
  • ref_idx_l1 is a syntax element indicating the second reference picture among the reference pictures included in the L1
  • mvp_l0_flag is the A syntax element indicating the MVPL0 among the MVPL0 candidates included in the MVPL0 candidate list
  • mvp_l1_flag is a syntax element indicating the MVPL1 among the MVPL1 candidates included in the MVPL1 candidate list
  • mvd_coding is a syntax element indicating the MVDL0 and / or the MVDL1
  • ref_idx_l2 Is the first reference picture among the reference pictures included in the L
  • ref_idx_l2 may be a syntax element representing the first index.
  • the syntax element representing the first index may be referred to as ref_idx_l2 or may be referred to as a name different from ref_idx_l2.
  • the ref_idx_l0 may be transmitted when the L0 prediction is performed on the current block
  • the ref_idx_l1 may be transmitted when the L1 prediction is performed on the current block
  • the ref_idx_l2 is the pair prediction on the current block. May be sent if this is done.
  • the mvp_l0_flag may be transmitted when the L0 prediction or the pair prediction is performed on the current block
  • the mvp_l1_flag may be transmitted when the L1 prediction or the pair prediction is performed on the current block.
  • the mvd_coding may include the MVDL0 and / or the MVDL1, and each MVD may be composed of x and y components, and the code and size of each component may be transmitted separately.
  • the ref_idx_l2 may indicate both an index indicating the first reference picture among the reference pictures included in the L0 and an index indicating the second reference picture among the reference pictures included in the L1, and thus indicate the ref_idx_l2.
  • the L0 motion information may include an index of the first reference picture
  • the L1 motion information may include an index of the second reference picture
  • the value of ref_idx_l2 is an index of the first reference picture.
  • a combination of indices of the second reference pictures may be derived.
  • the value of the index of the first reference picture and the value of the index of the second reference picture which the value of ref_idx_l2 means may be defined as shown in the following table.
  • ref_idx_l0 is an index indicating the first reference picture among the reference pictures included in the L0
  • ref_idx_l1 is an index indicating the second reference picture among the reference pictures included in the L1
  • ref_idx_l2 is a reference included in the L0.
  • the first index may indicate both an index indicating the first reference picture among pictures and an index indicating the second reference picture among reference pictures included in the L1.
  • Table 4 for example, when the value of ref_idx_l2 is 0, the value of ref_idx_l0 may be 0 and the value of ref_idx_l1 for L1 may be 0.
  • the value of ref_idx_l2 when the value of ref_idx_l2 is 1, the value of ref_idx_l0 may be 0, and the value of ref_idx_l1 for L1 may be 1, and when the value of ref_idx_l2 is 2, the value of ref_idx_l0 is 1 and the L1.
  • the value of ref_idx_l1 may indicate 0, and when the value of ref_idx_l2 is 3, the value of ref_idx_l0 may be 1 and the value of ref_idx_l1 for L1 may be 1.
  • the combination of the index of the first reference picture and the index of the second reference picture which the value of ref_idx_l2 means is not limited to the example shown in Table 4, and there may be other examples, and may be included in L0 and / or L1. It may be adaptively determined according to the number of reference pictures.
  • the ref_idx_l2 may be coded by applying various binarization methods.
  • the value of ref_idx_l2 may be coded by applying a binarization method as shown in Table 5 below.
  • ref_idx_l2 indicates a syntax element of the first index indicating both an index indicating the first reference picture among the reference pictures included in the L0 and an index indicating the second reference picture among the reference pictures included in the L1.
  • the bin string represents binary data derived by applying a binarization method. As shown in Table 5, the number of bits of ref_idx_l2 may be variable. For example, the bin string indicating when the value of ref_idx_l2 is 0 is 0, the bin string indicating when the value of ref_idx_l2 is 1 is 10, and the bin string indicating when the value of ref_idx_l2 is 2 is binarized to 110. Can be.
  • the binarization method of ref_idx_l2 is not limited to the binarization method shown in Table 5, and another binarization method may be applied, and may be adaptively determined according to the number of reference pictures included in the L0 and the reference pictures included in the L1. have.
  • the coding apparatus may represent a high value of the ratio derived in the image among the values of ref_idx_l2 as a bin string having a small number of bits, thereby improving the overall coding efficiency by reducing the data amount of ref_idx_l2 in the image. have.
  • an index indicating both the MVPL0 and the MVPL1 may be transmitted. That is, the MVPL0 and the MVPL1 may be derived based on the index.
  • an MVPL0 candidate indicated by the index among the MVPL0 candidates of the MVPL0 candidate list may be derived as the MVPL0
  • an MVPL1 candidate indicated by the index among the MVPL1 candidates in the MVPL1 candidate list may be derived as the MVPL1.
  • the L0 motion information may include the MVPL0
  • the L1 motion information may include the MVPL1
  • a syntax element representing both the L0 motion information and the L1 motion information indicates the MVPL0 and the MVPL1. May indicate the index pointed to.
  • the index indicating the MVPL0 and the MVPL1 may be referred to as a second index.
  • a syntax structure including a syntax element representing both the L0 motion information and the L1 motion information may be represented as shown in the following table.
  • x0 and y0 indicate the position (x0, y0) of the top-left sample of the current block
  • inter_pred_idc indicates whether the prediction performed on the current block is L0 prediction, L1 prediction, or pair prediction.
  • a syntax element indicating a ref_idx_l0 is a syntax element indicating the first reference picture among the reference pictures included in the L0
  • ref_idx_l1 is a syntax element indicating the second reference picture among the reference pictures included in the L1
  • mvp_l0_flag is the A syntax element indicating the MVPL0 among the MVPL0 candidates included in the MVPL0 candidate list
  • mvp_l1_flag is a syntax element indicating the MVPL1 among the MVPL1 candidates included in the MVPL1 candidate list
  • mvd_coding is a syntax element indicating the MVDL0 and / or the MVDL1, mvp_l2_idx Is selected from among the MVPL0 candidates included in the
  • mvp_l2_idx may be a syntax element representing the second index.
  • the syntax element representing the second index may be called mvp_l2_idx or may be called a different name from mvp_l2_idx.
  • the mvp_l0_flag may be transmitted when the L0 prediction is performed on the current block
  • the mvp_l1_flag may be transmitted when the L1 prediction is performed on the current block
  • the mvp_l2_idx is the pair prediction on the current block May be sent if this is done.
  • the ref_idx_l0 may be transmitted when the L0 prediction or the pair prediction is performed on the current block
  • the ref_idx_l1 may be transmitted when the L1 prediction or the pair prediction is performed on the current block.
  • the mvd_coding may include the MVDL0 and / or the MVDL1, and each MVD may be composed of x and y components, and the code and size of each component may be transmitted separately.
  • the mvp_l2_idx may indicate both a flag indicating the MVPL0 among the MVPL0 candidates included in the MVPL0 candidate list and a flag indicating the MVPL1 among the MVPL1 candidates included in the MVPL1 candidate list, and thus, the MVPL0 based on the mvp_l2_idx.
  • the MVPL1 can be derived. That is, the L0 motion information may include the MVPL0, the L1 motion information may include the MVPL1, and the value of mvp_l2_idx may indicate a combination of a flag indicating the MVPL0 and a flag indicating the MVPL1. .
  • the value of the flag indicating the MVPL0 and the value of the flag indicating the MVPL1 which the value of mvp_l2_idx means may be defined as shown in the following table.
  • mvp_l0_flag is a flag indicating the MVPL0 among the MVPL0 candidates included in the MVPL0 candidate list
  • mvp_l1_flag is a flag indicating the MVPL1 among the MVPL1 candidates included in the MVPL1 candidate list
  • mvp_l2_idx is the MVPL0 candidate included in the MVPL0 candidate list.
  • the second index indicating both the flag indicating the MVPL0 and the flag indicating the MVPL1 among the MVPL1 candidates included in the MVPL1 candidate list may be indicated.
  • the value of mvp_l2_idx when the value of mvp_l2_idx is 0, the value of mvp_l0_flag may be 0 and the value of mvp_l1_flag may be 0.
  • the value of mvp_l2_idx when the value of mvp_l2_idx is 1, the value of mvp_l0_flag may be 0 and the value of mvp_l1_flag may be 1, and when the value of mvp_l2_idx is 2, the value of mvp_l0_flag is 1 and the value of mvp_l1_flag is When the value of the mvp_l2_idx is 3, the value of the mvp_l0_flag may be 1, and the value of the mvp_l1_flag may be 1.
  • the mvp_l2_idx may be coded by applying various binarization methods.
  • the value of mvp_l2_idx may be coded by applying a binarization method as shown in Table 8 below.
  • mvp_l2_idx indicates a syntax element of the second index indicating both a flag indicating the MVPL0 among the MVPL0 candidates included in the MVPL0 candidate list and a flag indicating the MVPL1 among the MVPL1 candidates included in the MVPL1 candidate list, and a bin string.
  • the bin string representing the case where the value of mvp_l2_idx is 0 is 0, the bin string representing the case where the value of mvp_l2_idx is 1 is 10, and the bin string representing the case where the value of mvp_l2_idx is 2 is binarized.
  • the binarization method of mvp_l2_idx is not limited to the binarization method shown in Table 8 above, and other binarization methods may be applied.
  • the binarization method of mvp_l2_idx may be adaptively determined according to the maximum number or available number of mvp_l0_flag and / or mvp_l1_flag.
  • the bin string representing the value of mvp_l2_idx is the number of candidates included in the MVPL0 candidate list and / or the MVPL1 candidate list and the candidate block included in the MVPL0 candidate list and / or the candidates included in the MVPL1 candidate list. It may be adaptively determined according to the number of candidates used for inter prediction.
  • a bin string representing the value of the mvp_l2_idx may be determined.
  • an index is assigned to each of the candidates included in the MVPL0 candidate list or the MVPL1 candidate list, and some of the candidates, for example, two candidates are selected to select the mvp_l0_flag or the mvp_l1_flag value. Can be derived according to.
  • the coding apparatus may indicate only some cases of mvp_l2_idx, not all cases of the combination of the value of mvp_l0_flag and the value of mvp_l1_flag. Specifically, the coding apparatus may select only two cases of all cases of the combination of the value of mvp_l0_flag and the value of mvp_l1_flag, and make mvp_l2_idx operate as a flag indicating the two cases.
  • the coding apparatus may represent a high value derived from the image of mvp_l2_idx as a bin string having a small number of bits, thereby improving the overall coding efficiency by reducing the data amount of mvp_l2_idx in the input image. Can be.
  • the first reference picture, the second reference picture, the MVPL0, and the MVPL1 may be selected.
  • a reference picture indicated by the index among the reference pictures of L0 may be derived as the first reference picture
  • a reference picture indicated by the index among the reference pictures of L1 may be derived as the second reference picture.
  • the MVPL0 candidate indicated by the index among the MVPL0 candidates of the MVPL0 candidate list may be derived as the MVPL0
  • the MVPL1 candidate indicated by the index among the MVPL1 candidates in the MVPL1 candidate list may be derived as the MVPL1.
  • the L0 motion information may include an index of the first reference picture and the MVPL0
  • the L1 motion information may include an index of the second reference picture and the MVPL1
  • the L0 motion information and A syntax element representing all of the L1 motion information may indicate the index indicating the first reference picture, the second reference picture, the MVPL0, and the MVPL1.
  • the index indicating the first reference picture, the second reference picture, the MVPL0 and the MVPL1 may be referred to as a third index.
  • a syntax structure including a syntax element representing the third index indicating both the L0 motion information and the L1 motion information may be represented as in the following table.
  • x0 and y0 indicate the position (x0, y0) of the top-left sample of the current block
  • inter_pred_idc indicates whether the prediction performed on the current block is L0 prediction, L1 prediction, or pair prediction.
  • a syntax element indicating a ref_idx_l0 is a syntax element indicating the first reference picture among the reference pictures included in the L0
  • ref_idx_l1 is a syntax element indicating the second reference picture among the reference pictures included in the L1
  • mvp_l0_flag is the A syntax element indicating the MVPL0 among the MVPL0 candidates included in the MVPL0 candidate list
  • mvp_l1_flag is a syntax element indicating the MVPL1 among the MVPL1 candidates included in the MVPL1 candidate list
  • mvd_coding is a syntax element indicating the MVDL0 and / or the MVDL1, mvp_ref_idx Is the first reference picture among the reference pictures included in the
  • the syntax element representing the third index may be mvp_ref_idx.
  • the syntax element of the third index may be referred to as mvp_ref_idx or may be referred to as a name different from mvp_ref_idx.
  • the ref_idx_l0 and the mvp_l0_flag may be transmitted when the L0 prediction is performed on the current block, and the ref_idx_l1 and the mvp_l1_flag may be transmitted when the L1 prediction is performed on the current block.
  • the mvp_ref_idx may be transmitted.
  • the mvd_coding may include the MVDL0 and / or the MVDL1, and each MVD may be composed of x and y components, and the code and size of each component may be transmitted separately.
  • the mvp_ref_idx is an index indicating the first reference picture among the reference pictures included in the L0, an index indicating the second reference picture among the reference pictures included in the L1, and MVPL0 candidates included in the MVPL0 candidate list.
  • the flag indicating the MVPL0 and the flag indicating the MVPL1 among the MVPL1 candidates included in the MVPL1 candidate list may be indicated. Accordingly, the first reference picture, the second reference picture, the MVPL0 and the MVP are based on the mvp_ref_idx. MVPL1 can be derived.
  • the L0 motion information may include an index of the first reference picture and the MVPL0
  • the L1 motion information may include an index of the second reference picture and the MVPL1
  • the value of mvp_ref_idx is equal to the The combination of an index of a first reference picture, an index of the second reference picture, a flag indicating the MVPL0, and a flag indicating the MVPL1 may be indicated.
  • the value of the index of the first reference picture, the value of the index of the second reference picture, the value of the flag indicating the MVPL0, and the value of the flag indicating the MVPL1 means It can be defined as
  • ref_idx_l0 is an index indicating the first reference picture among the reference pictures included in the L0
  • ref_idx_l1 is an index indicating the second reference picture among the reference pictures included in the L1
  • mvp_l0_flag is included in the MVPL0 candidate list.
  • the third index may be indicated.
  • the value of ref_idx_l0 when the value of mvp_ref_idx is 0, the value of ref_idx_l0 may be 0, the value of ref_idx_l1 is 0, the value of mvp_l0_flag is 0, and the value of mvp_l1_flag is 0.
  • the value of mvp_ref_idx is 1, the value of ref_idx_l0 is 0, the value of ref_idx_l1 is 0, the value of mvp_l0_flag is 0, the value of mvp_l1_flag is 1, and the value of mvp_ref_idx is 2.
  • the value of ref_idx_l0 When the value of ref_idx_l0 is 0, the value of ref_idx_l1 is 0, the value of mvp_l0_flag is 1, the value of mvp_l1_flag is 0, and when the value of mvp_ref_idx is 3, the value of ref_idx_l0 is 0,
  • the value of ref_idx_l1 may be 0, the value of mvp_l0_flag is 1, and the value of mvp_l1_flag may be 1.
  • the value of the index indicating the first reference picture, the value of the index indicating the second reference picture, the value of the flag indicating the MVPL0 and the value of the flag indicating the MVPL1 are indicated in Table 10.
  • the value of the index indicating the first reference picture, the value of the index indicating the second reference picture, the flag indicating the MVPL0, and the value of the flag indicating the MVPL1 mean the value L0 and / or It may be adaptively determined according to the number of reference pictures included in the L1 or the number of candidates included in the MVPL0 candidate list and / or the MVPL1 candidate list or the number of candidates available for inter prediction of the current block among the candidates. have.
  • the mvp_ref_idx may be coded by applying various binarization methods.
  • the value of mvp_ref_idx may be coded by applying a binarization method as shown in Table 11 below.
  • mvp_ref_idx is an index indicating the first reference picture among the reference pictures included in the L0, an index indicating the second reference picture among the reference pictures included in the L1, and among MVPL0 candidates included in the MVPL0 candidate list.
  • Binary data indicates a syntax element of the third index indicating both the flag indicating the MVPL0 and the flag indicating the MVPL1 among the MVPL1 candidates included in the MVPL1 candidate list, and the bin string is binary data derived by applying a binarization method. Indicates. As shown in Table 11, the number of bits of mvp_ref_idx may be variable.
  • the bin string representing the case where the value of mvp_ref_idx is 0 is 0, the bin string representing the case where the value of mvp_ref_idx is 1 is 10, and the bin string representing the case where the value of mvp_ref_idx is 2 is binarized to 110.
  • the binarization method of mvp_ref_idx is not limited to the binarization method shown in Table 11 above, and other binarization methods may be applied.
  • a flag indicating whether to use a syntax element representing both the L0 motion information and the L1 motion information described above in a slice unit may be transmitted / received.
  • a flag indicating whether to use the first index among the reference pictures included in the L0 and the first index indicating the second reference picture among the reference pictures included in the L1 may be transmitted in a slice unit.
  • the flag indicating whether the first index is used may be referred to as a first flag.
  • a syntax structure including a syntax element representing the first flag may be represented as in the following table.
  • slice_ref_idx_l2_flag represents a syntax element indicating whether to use an index indicating the first reference picture and the second reference picture. That is, the slice_ref_idx_l2_flag may be a syntax element representing the first flag.
  • the syntax element representing the first flag may be referred to as slice_ref_idx_l2_flag, or may be referred to as a name different from the slice_ref_idx_l2_flag.
  • an index indicating the first reference picture among the reference pictures included in the L0 and the L1 included in the L1 are included.
  • the index indicating the second reference picture among reference pictures may be transmitted. That is, an index indicating the first reference picture and an index indicating the second reference picture for the block included in the target slice may be encoded, respectively.
  • the first reference picture among the reference pictures included in the L0 and the first picture among the reference pictures included in the L1 The first index indicating the two reference pictures may be transmitted. That is, the first index indicating the first reference picture and the second reference picture for the block included in the target slice may be encoded.
  • a flag indicating whether to use the second index indicating the MVPL1 among the MVPL0 candidates included in the MVPL0 candidate list and the MVPL1 candidates included in the MVPL1 candidate list may be transmitted in a slice unit. That is, a flag indicating whether the MVPL0 and the second index indicating the MVPL1 is used may be transmitted through a slice segment header. The flag indicating whether the second index is used may be referred to as a second flag.
  • the syntax structure including the syntax element representing the second flag may be represented as the following table.
  • slice_mvp_l2_flag represents a syntax element indicating whether to use the index indicating the MVPL0 and the MVPL1. That is, the slice_mvp_l2_flag may be a syntax element representing the second flag.
  • the syntax element representing the second flag may be referred to as slice_mvp_l2_flag or may be referred to as a name different from the slice_mvp_l2_flag.
  • a flag indicating the MVPL0 among the MVPL0 candidates included in the MVPL0 candidate list and the MVPL1 candidate list are included in the MVPL0 candidate list.
  • a flag indicating the MVPL1 may be transmitted. That is, a flag indicating the MVPL0 and a flag indicating the MVPL1 for the block included in the target slice may be encoded.
  • the slice_mvp_l2_flag value is 1
  • the MVPL0 candidates included in the MVPL0 candidate list and the MVPL1 candidates included in the MVPL1 candidate list are selected.
  • the second index pointing may be transmitted. That is, the MVPL0 and the second index indicating the MVPL1 for the block included in the target slice may be encoded.
  • a flag indicating whether the third index indicating the MVPL1 is used among the MVPL1 candidates included in the slice may be transmitted. That is, a flag indicating whether to use the first reference picture, the second reference picture, the MVPL0, and the third index indicating the MVPL1 may be transmitted through a slice segment header.
  • the flag indicating whether the third index is used may be referred to as a third flag.
  • the syntax structure including the syntax element representing the third flag may be represented as the following table.
  • slice_mvp_ref_l2_flag indicates a syntax element indicating whether the third index indicating the first reference picture, the second reference picture, the MVPL0, and the MVPL1 is used. That is, slice_mvp_ref_l2_flag may be a syntax element representing the third flag.
  • the syntax element representing the third flag may be referred to as slice_mvp_ref_l2_flag or may be referred to as a name different from the slice_mvp_ref_l2_flag.
  • an index indicating the first reference picture among the reference pictures included in the L0, included in the L1 An index indicating the second reference picture among the reference pictures, a flag indicating the MVPL0 among the MVPL0 candidates included in the MVPL0 candidate list, and a flag indicating the MVPL1 among the MVPL1 candidates included in the MVPL1 candidate list may be transmitted. . That is, an index indicating the first reference picture, an index indicating the second reference picture, a flag indicating the MVPL0, and a flag indicating the MVPL1 may be encoded for the block included in the target slice.
  • the value of the slice_mvp_ref_l2_flag 1
  • the first reference picture among the reference pictures included in the L0 and the first picture among the reference pictures included in the L1 A second reference picture, the MVPL0 candidates included in the MVPL0 candidate list and the third index indicating the MVPL1 among the MVPL1 candidates included in the MVPL1 candidate list may be transmitted. That is, the third index indicating the first reference picture, the second reference picture, the MVPL0 and the MVPL1 for the block included in the target slice may be encoded.
  • the first index pointing to the first reference picture and the second reference picture, the MVPL0 and the second index pointing to the MVPL1, and the first reference picture, the second reference picture, the MVPL0, and the Mode information indicating an index indicated by a syntax element indicating the L0 motion information and the L1 motion information for the current block among the third indexes indicating MVPL1 may be transmitted.
  • the mode information may be transmitted in units of slices.
  • a syntax structure including a syntax element representing the mode information may be represented as in the following table.
  • slice_mvp_ref_l2_mode represents a syntax element representing the mode information.
  • an index indicated by a syntax element representing the L0 motion information and the L1 motion information for the block may be derived based on the value of the mode information.
  • the index indicated by the syntax element indicated by the value of the mode information may be represented as shown in the following table.
  • slice_mvp_ref_l2_mode represents a syntax element representing the mode information.
  • the syntax element representing the mode information may be called slice_mvp_ref_l2_mode, or may be called a different name from slice_mvp_ref_l2_mode. If the value of the mode information is 0, when pair prediction is applied to a block included in the target slice, an index indicating the first reference picture among the reference pictures included in the L0, and among the reference pictures included in the L1, An index indicating the second reference picture, a flag indicating the MVPL0 among the MVPL0 candidates included in the MVPL0 candidate list, and a flag indicating the MVPL1 among the MVPL1 candidates included in the MVPL1 candidate list may be transmitted.
  • an index indicating the first reference picture, an index indicating the second reference picture, a flag indicating the MVPL0, and a flag indicating the MVPL1 may be encoded for the block included in the target slice.
  • the value of the mode information is 1, when pair prediction is applied to a block included in the target slice, the first reference picture among the reference pictures included in the L0 and the reference picture included in the L1 may be used.
  • the first index indicating the second reference picture may be transmitted. That is, the first index indicating the first reference picture and the second reference picture for the block included in the target slice may be encoded.
  • the MVPL1 candidates included in the MVPL0 candidate list and the MVPL1 candidates included in the MVPL0 candidate list are included in the MVPL0 candidate list.
  • the second index pointing to may be transmitted. That is, the MVPL0 and the second index indicating the MVPL1 for the block included in the target slice may be encoded.
  • the value of the mode information is 3 when pair prediction is applied to a block included in the target slice, the first reference picture among the reference pictures included in the L0 and the reference picture among the reference pictures included in the L1 may be used.
  • a second reference picture, the MVPL0 candidates included in the MVPL0 candidate list and the third index indicating the MVPL1 among the MVPL1 candidates included in the MVPL1 candidate list may be transmitted. That is, the third index indicating the first reference picture, the second reference picture, the MVPL0 and the MVPL1 for the block included in the target slice may be encoded.
  • the first flag, the second flag, the third flag, and the mode information shown in Tables 12 to 15 described above are not only a slice unit but also a sequence parameter set (SPS) unit and a picture parameter set (PPS) unit. Or may be transmitted through a high-level syntax such as a video parameter set (VPS) unit and may be applied. Also, a flag indicating whether to use a syntax element indicating L0 motion information and L1 motion information may be transmitted through an SPS unit, a PPS unit, or a VPS unit, and the flag may indicate a syntax element indicating L0 motion information and L1 motion information. In the case of indicating that is used, the mode information may be transmitted in units of slices.
  • FIG. 5 schematically illustrates a video encoding method by an encoding device according to the present invention.
  • the method disclosed in FIG. 5 may be performed by the encoding apparatus disclosed in FIG. 1.
  • S500 to S530 of FIG. 5 may be performed by the prediction unit of the encoding apparatus
  • S540 may be performed by the entropy encoding unit of the encoding apparatus.
  • the encoding apparatus derives the reference picture list 0 (list 0, L0) and the reference picture list 1 (List 1, L1) (S500).
  • the encoding apparatus may derive the L0 and the L1 for the current picture including the current block.
  • the reference pictures included in the L0 and the L1 may be arranged based on a difference in picture order count (POC) between the current picture and the reference picture.
  • POC corresponds to the display order of the pictures and may be distinguished from the coding order.
  • the encoding apparatus derives the L0 motion information and the L1 motion information for the current block (S510).
  • the encoding apparatus may derive the L0 motion information and the L1 motion information when bi-prediction is applied to the current block.
  • the encoding apparatus performs an optimal motion vector L0 (MVL0) through motion estimation, a first reference picture of the current block included in the L0, a motion vector L1 (MVL1), and A second reference picture of the current block included in the L1 may be derived.
  • the encoding apparatus may derive a motion vector most similar to the MVL0 among the motion vectors of neighboring blocks of the current block to a motion vector predictor L0 (MVL0), and determine the neighboring blocks of the current block.
  • the motion vector most similar to the MVL1 among the motion vectors may be derived as a motion vector predictor L1 (MVL1).
  • the L0 motion information may include at least one of an index of a first reference picture of the current block included in the L0 and the MVPL0 associated with the first reference picture, wherein the L1 motion information is included in the L1. It may include at least one of the index of the second reference picture of the included current block and the MVPL1 associated with the second reference picture.
  • the encoding apparatus may derive the difference between the MVL0 and the MVPL0 as a motion vector difference L0 (MVDL0) for the MVPL0, and calculate the difference between the MVL1 and the MVPL1 as the motion vector difference for the MVPL1. It can be derived as L1 (Motion Vector Difference L1, MVDL0).
  • the encoding apparatus may signal the information on the MVDL0 and the information on the MVDL1 through a bitstream.
  • the encoding apparatus derives a prediction sample of the current block based on the L0 motion information and the L1 motion information (S520).
  • the encoding apparatus may derive the prediction sample of the current block by performing pair prediction based on the L0 motion information and the L1 motion information.
  • the encoding apparatus generates a syntax element representing the L0 motion information and the L1 motion information for the current block (S530).
  • the encoding apparatus may generate a syntax element representing the L0 motion information and the L1 motion information for the current block.
  • the L0 motion information and the L1 motion information for the current block may be derived based on the syntax element.
  • the L0 motion information may include an index of a first reference picture of the current block included in the L0 and the MVPL0 associated with the first reference picture, wherein the L1 motion information is included in the L1.
  • It may include the index of the second reference picture of the current block and the MVPL1 associated with the second reference picture, the value of the syntax element representing the L0 motion information and the L1 motion information is the index of the first reference picture And a combination of the index of the second reference picture, or a combination of the flag representing the MVPL0 and the flag representing the MVPL1, or the index of the first reference picture, the index of the second reference picture, the flag representing the MVPL0, and the A combination of flags indicating MVPL1 may be indicated.
  • a syntax element representing the L0 motion information and the L1 motion information may indicate a first index indicating the first reference picture and the second reference picture. That is, the value of the first index may represent a combination of the index of the first reference picture and the index of the second reference picture.
  • the encoding apparatus may generate the first index when the pair prediction is performed on the current block.
  • the first reference picture and the second reference picture may be derived based on the first index.
  • the value of the first index may represent a combination of the index of the first reference picture and the index of the second reference picture, and the index of the first reference picture in the combination among the reference pictures of L0 is
  • the pointing reference picture may be derived as the first reference picture
  • the reference picture indicated by the index of the second reference picture in the combination among the reference pictures of L1 may be derived as the second reference picture.
  • the value of the index of the first reference picture and the value of the index of the second reference picture indicated by the value of the first index may be determined as shown in Table 4 above.
  • the syntax element representing the L0 motion information and the L1 motion information may indicate the MVPL0 and a second index indicating the MVPL1. That is, the value of the second index may represent a combination of a flag indicating the MVPL0 and a flag indicating the MVPL1.
  • the encoding apparatus may generate the second index when the pair prediction is performed on the current block.
  • the MVPL0 and the MVPL1 may be derived based on the second index.
  • the value of the second index may represent a combination of a flag indicating the MVPL0 and a flag indicating the MVPL1, and the MVPL0 candidate list including the MVPL0 candidates and the MVPL1 candidate list including the MVPL1 candidates are neighboring blocks of the current block.
  • the MVPL0 candidate indicated by the flag indicating the MVPL0 in the combination among the MVPL0 candidates in the MVPL0 candidate list may be derived as the MVPL0, and the combination among the MVPL1 candidates in the MVPL1 candidate list.
  • the MVPL1 candidate indicated by the flag indicating the MVPL1 in the group may be derived as the MVPL1.
  • the value of the flag of the MVPL0 and the value of the flag of the MVPL1 indicated by the value of the second index may be determined as shown in Table 7 above.
  • the syntax element representing the L0 motion information and the L1 motion information may include the first reference picture, the second reference picture, the MVPL0, and a third index indicating the MVPL1. That is, the value of the third index may represent a combination of an index of the first reference picture, an index of the second reference picture, a flag indicating the MVPL0, and a flag indicating the MVPL1.
  • the encoding apparatus may generate the third index when the pair prediction is performed on the current block.
  • the first reference picture, the second reference picture, the MVPL0 and the MVPL1 may be derived based on the third index.
  • the value of the third index may represent a combination of an index of the first reference picture, an index of the second reference picture, a flag indicating the MVPL0, and a flag indicating the MVPL1, and reference pictures of the L0.
  • the reference picture indicated by the index of the first reference picture in the combination may be derived as the first reference picture
  • the reference picture indicated by the index of the second reference picture in the combination among the reference pictures of L1 may be determined by the reference picture. It can be derived as a second reference picture.
  • an MVPL0 candidate list including MVPL0 candidates and an MVPL1 candidate list including MVPL1 candidates may be derived based on motion vectors of neighboring blocks of the current block, and represent the MVPL0 in the combination of MVPL0 candidates in the MVPL0 candidate list.
  • the MVPL0 candidate indicated by the flag may be derived as the MVPL0
  • the MVPL1 candidate indicated by the flag indicating the MVPL0 in the combination among the MVPL1 candidates in the MVPL1 candidate list may be derived as the MVPL1.
  • the value of the index of the first reference picture indicated by the value of the third index, the value of the index of the second reference picture, the value of the flag of MVPL0 and the value of the flag of MVPL1 are shown in Table 10 above. Can be determined.
  • the encoding apparatus encodes and outputs a syntax element representing the L0 motion information and the L1 motion information for the current block (S540).
  • the encoding apparatus may encode and output a syntax element representing the L0 motion information and the L1 motion information for the current block in a bitstream form.
  • the encoding apparatus may encode the syntax element representing the first index to have a variable number of bits according to the value of the first index.
  • the syntax element representing the first index may be binarized to have a variable number of bits, and the number of bits of the syntax element representing the first index may be variable.
  • the encoding apparatus may binarize a value having a high bit rate among the values of the first index to have a small number of bits, and a value having a low bit rate having a high number of bits to have a large number of bits.
  • the binarization method of the first index may be determined as shown in Table 5 above.
  • the encoding apparatus may have the syntax element representing the second index to have a variable number of bits according to the value of the second index.
  • the syntax element representing the second index may be binarized to have a variable number of bits, and the number of bits of the syntax element representing the second index may be variable.
  • the encoding apparatus may binarize a value having a high bit rate among the values of the second index to have a small number of bits, and have a large number of bits having a low ratio of the value derived from the image.
  • the binarization method of the second index may be determined as shown in Table 8 above.
  • the encoding apparatus may have the syntax element representing the third index to have a variable number of bits according to the value of the third index.
  • the syntax element representing the third index may be binarized to have a variable number of bits, and the number of bits of the syntax element representing the third index may be variable.
  • the encoding apparatus may binarize a value having a high ratio derived in the image among the values of the third index to have a small number of bits, and have a large number of bits having a low ratio derived in the image.
  • the binarization method of the third index may be determined as shown in Table 11 above.
  • the encoding apparatus may generate a flag indicating whether the first index, the second index, and / or the third index are used.
  • the flag may be transmitted in a slice unit, a sequence parameter set (SPS) unit, a picture parameter set (PPS) unit, or a video parameter set (VPS) unit.
  • SPS sequence parameter set
  • PPS picture parameter set
  • VPS video parameter set
  • a first flag indicating whether the first index is used may be generated and transmitted in a slice unit.
  • the first flag may be transmitted in an SPS unit, a PPS unit, or a VPS unit.
  • the syntax element may indicate the first index. That is, the encoding apparatus may encode and output the syntax element representing the first index.
  • the index indicating the first reference picture among the reference pictures included in the L0 and the reference picture included in the L1 may be used. Indices indicating the second reference pictures may be transmitted, respectively.
  • a second flag indicating whether the second index is used may be generated and transmitted in a slice unit.
  • the second flag may be transmitted in an SPS unit, a PPS unit, or a VPS unit.
  • the syntax element may indicate the second index.
  • the encoding apparatus may encode and output the syntax element indicating the second index.
  • a flag indicating the MVPL0 among the MVPL0 candidates included in the MVPL0 candidate list and the MVPL1 among the MVPL1 candidates included in the MVPL1 candidate list Each flag indicating may be transmitted.
  • a third flag indicating whether the third index is used may be generated and transmitted in a slice unit.
  • the third flag may be transmitted in an SPS unit, a PPS unit, or a VPS unit.
  • the syntax element may indicate the third index. That is, the encoding device may encode and output the syntax element representing the third flag.
  • an index indicating the first reference picture among reference pictures included in the L0 and the reference picture among the reference pictures included in the L1 may be used.
  • An index indicating a second reference picture, a flag indicating the MVPL0 among the MVPL0 candidates included in the MVPL0 candidate list, and a flag indicating the MVPL1 among the MVPL1 candidates included in the MVPL1 candidate list may be transmitted.
  • mode information indicated by the syntax element among the first index, the second index, and the third index may be generated and transmitted in a slice unit.
  • the index may be transmitted in units of SPS, units of PPS, or units of VPS.
  • the syntax element may indicate the first index.
  • the encoding apparatus may encode and output a syntax element indicating the first index.
  • the syntax element may indicate the second index.
  • the encoding apparatus may encode and output a syntax element indicating the second index.
  • the syntax element may indicate the third index.
  • the encoding apparatus may encode and output a syntax element indicating the third index.
  • an index indicating the first reference picture among the reference pictures included in the L0, and the first of the reference pictures included in the L1 An index indicating a reference picture, a flag indicating the MVPL0 among the MVPL0 candidates included in the MVPL0 candidate list, and a flag indicating the MVPL1 among the MVPL1 candidates included in the MVPL1 candidate list may be transmitted.
  • the encoding apparatus may encode the mode information to have a variable number of bits according to the value of the mode information.
  • the mode information may be binarized to have a variable number of bits, and the number of bits of the mode information may be variable.
  • the encoding apparatus may binarize a value having a high ratio derived in the image among the values of the mode information to have a small number of bits and a large number of bits having a low ratio derived in the image.
  • a flag indicating whether to use a syntax element indicating L0 motion information and L1 motion information may be transmitted through an SPS unit, a PPS unit, or a VPS unit, and the flag may indicate a syntax element indicating L0 motion information and L1 motion information. For example, when the value of the flag is 1, the mode information may be transmitted in units of slices.
  • the encoding apparatus may generate a residual sample based on the original sample and the derived prediction sample.
  • the encoding apparatus may generate information about the residual based on the residual sample.
  • the information about the residual may include transform coefficients related to the residual sample.
  • the encoding apparatus may derive the reconstructed sample based on the prediction sample and the residual sample. That is, the encoding apparatus may derive the reconstructed sample by adding the prediction sample and the residual sample.
  • the encoding apparatus may encode the information about the residual and output the bitstream.
  • the bitstream may be transmitted to a decoding apparatus via a network or a storage medium.
  • FIG. 6 schematically illustrates a video decoding method by a decoding apparatus according to the present invention.
  • the method disclosed in FIG. 6 may be performed by the decoding apparatus disclosed in FIG. 2.
  • S600 and S620 to S630 may be performed by the prediction unit of the decoding apparatus
  • S610 may be performed by the entropy decoding unit of the decoding apparatus.
  • the decoding apparatus derives the reference picture list 0 (list 0, L0) and the reference picture list 1 (List 1, L1) (S600).
  • the encoding apparatus may derive the L0 and the L1 for the current picture including the current block.
  • the reference pictures included in the L0 and the L1 may be arranged based on a difference in picture order count (POC) between the current picture and the reference picture.
  • POC corresponds to the display order of the pictures and may be distinguished from the coding order.
  • the decoding apparatus receives a syntax element representing the L0 motion information and the L1 motion information for the current block through the bitstream (S610).
  • the decoding apparatus may receive a syntax element representing the L0 motion information and the L1 motion information for the current block through the bitstream.
  • the L0 motion information may include at least one of an index of a first reference picture of the current block included in the L0 and the motion vector predictor L0 (MVL0) associated with the first reference picture.
  • the L1 motion information may include at least one of an index of a second reference picture of the current block included in the L1 and the motion vector predictor L1 (MVL1) associated with the second reference picture. have.
  • the value of the syntax element representing the L0 motion information and the L1 motion information may be a combination of an index of the first reference picture and an index of the second reference picture, or a combination of a flag representing the MVPL0 and a flag representing the MVPL1, or The combination of an index of a first reference picture, an index of the second reference picture, a flag indicating the MVPL0, and a flag indicating the MVPL1 may be indicated.
  • a syntax element representing the L0 motion information and the L1 motion information may include a first index indicating the first reference picture and the second reference picture. That is, the value of the first index may represent a combination of the index of the first reference picture and the index of the second reference picture.
  • the decoding apparatus may receive the first index for the current block.
  • the first reference picture and the second reference picture may be derived based on the first index.
  • the value of the first index may represent a combination of the index of the first reference picture and the index of the second reference picture, and the index of the first reference picture in the combination among the reference pictures of L0 is
  • the pointing reference picture may be derived as the first reference picture
  • the reference picture indicated by the index of the second reference picture in the combination among the reference pictures of L1 may be derived as the second reference picture.
  • the value of the index of the first reference picture and the value of the index of the second reference picture indicated by the value of the first index may be determined as shown in Table 4 above.
  • the number of bits of the syntax element representing the first index may be variable. That is, the syntax element that represents the first index may be binarized to a variable number of bits.
  • the syntax element indicating the first index may have a variable number of bits according to the value of the first index, and a small number of bits may be used as a value having a high ratio derived from an image among the values of the first index. In addition, a low value of the ratio derived in the image may have a large number of bits.
  • the syntax element indicating the first index may be binarized as shown in Table 5 above.
  • the syntax element representing the L0 motion information and the L1 motion information may include the MVPL0 and a second index indicating the MVPL1. That is, the value of the second index may represent a combination of a flag indicating the MVPL0 and a flag indicating the MVPL1.
  • the decoding device may receive the second index for the current block.
  • the MVPL0 and the MVPL1 may be derived based on the second index.
  • the value of the second index may represent a combination of a flag indicating the MVPL0 and a flag indicating the MVPL1, and the MVPL0 candidate list including the MVPL0 candidates and the MVPL1 candidate list including the MVPL1 candidates are neighboring blocks of the current block.
  • the MVPL0 candidate indicated by the flag indicating the MVPL0 in the combination among the MVPL0 candidates in the MVPL0 candidate list may be derived as the MVPL0, and the combination among the MVPL1 candidates in the MVPL1 candidate list.
  • the MVPL1 candidate indicated by the flag indicating the MVPL1 in the group may be derived as the MVPL1.
  • the value of the flag of the MVPL0 and the value of the flag of the MVPL1 indicated by the value of the second index may be determined as shown in Table 7 above.
  • the number of bits of the syntax element representing the second index may be variable. That is, the syntax element representing the second index may be binarized with a variable number of bits.
  • the syntax element representing the second index may have a variable number of bits according to the value of the second index, and a value having a small number of bits having a high ratio derived from an image among the values of the second index may be high. For example, a low value derived from an image may have a large number of bits.
  • the syntax element representing the second index may be binarized as shown in Table 8 above.
  • the syntax element representing the L0 motion information and the L1 motion information may include the first reference picture, the second reference picture, the MVPL0, and a third index indicating the MVPL1. That is, the value of the third index may represent a combination of an index of the first reference picture, an index of the second reference picture, a flag indicating the MVPL0, and a flag indicating the MVPL1.
  • the decoding apparatus may receive the third index for the current block.
  • the first reference picture, the second reference picture, the MVPL0 and the MVPL1 may be derived based on the third index.
  • the value of the third index may represent a combination of an index of the first reference picture, an index of the second reference picture, a flag indicating the MVPL0, and a flag indicating the MVPL1, and reference pictures of the L0.
  • the reference picture indicated by the index of the first reference picture in the combination may be derived as the first reference picture
  • the reference picture indicated by the index of the second reference picture in the combination among the reference pictures of L1 may be determined by the reference picture. It can be derived as a second reference picture.
  • an MVPL0 candidate list including MVPL0 candidates and an MVPL1 candidate list including MVPL1 candidates may be derived based on motion vectors of neighboring blocks of the current block, and represent the MVPL0 in the combination of MVPL0 candidates in the MVPL0 candidate list.
  • the MVPL0 candidate indicated by the flag may be derived as the MVPL0
  • the MVPL1 candidate indicated by the flag indicating the MVPL1 in the combination among the MVPL1 candidates in the MVPL1 candidate list may be derived as the MVPL1.
  • the value of the index of the first reference picture indicated by the value of the third index, the value of the index of the second reference picture, the value of the flag of MVPL0 and the value of the flag of MVPL1 are shown in Table 10 above. Can be determined.
  • the number of bits of the syntax element representing the third index may be variable. That is, the syntax element representing the third index may be binarized with a variable number of bits.
  • the syntax element representing the third index may have a variable number of bits according to the value of the third index, and a value having a high bit rate among the values of the third index has a high ratio derived in the image. For example, a low value derived from an image may have a large number of bits.
  • the syntax element representing the third index may be binarized as shown in Table 11 above.
  • the decoding apparatus may receive a flag indicating whether the first index, the second index, and / or the third index are used through the bitstream.
  • the flag may be received in a slice unit, a sequence parameter set (SPS) unit, a picture parameter set (PPS) unit, or a video parameter set (VPS) unit.
  • SPS sequence parameter set
  • PPS picture parameter set
  • VPS video parameter set
  • a first flag indicating whether the first index is used may be received in a slice unit.
  • the first flag may be received in an SPS unit, a PPS unit, or a VPS unit.
  • the syntax element may indicate the first index. That is, a syntax element representing the L0 motion information and the L1 motion information may indicate the first index.
  • the index indicating the first reference picture among the reference pictures included in the L0 and the reference picture included in the L1 may be used. Indices indicating the second reference pictures may be received respectively.
  • a second flag indicating whether the second index is used may be received in a slice unit.
  • the second flag may be received in an SPS unit, a PPS unit, or a VPS unit.
  • the syntax element may indicate the second index. That is, a syntax element representing the L0 motion information and the L1 motion information may indicate the second index.
  • a flag indicating the MVPL0 among the MVPL0 candidates included in the MVPL0 candidate list and the MVPL1 among the MVPL1 candidates included in the MVPL1 candidate list may be received respectively.
  • a third flag indicating whether the third index is used may be received in a slice unit.
  • the third flag may be received in an SPS unit, a PPS unit, or a VPS unit.
  • the syntax element may indicate the third index. That is, a syntax element representing the L0 motion information and the L1 motion information may indicate the third index.
  • an index indicating the first reference picture among reference pictures included in the L0 and the reference picture among the reference pictures included in the L1 may be used.
  • An index indicating a second reference picture, a flag indicating the MVPL0 among the MVPL0 candidates included in the MVPL0 candidate list, and a flag indicating the MVPL1 among the MVPL1 candidates included in the MVPL1 candidate list may be received.
  • an index indicating an index indicated by the syntax element among the first index, the second index, and the third index may be received in a slice unit.
  • the index may be received in units of SPS, units of PPS, or units of VPS.
  • the index may be called mode information.
  • the syntax element may indicate the first index. That is, a syntax element representing the L0 motion information and the L1 motion information may indicate the first index.
  • the syntax element may indicate the second index. That is, a syntax element representing the L0 motion information and the L1 motion information may indicate the second index.
  • the syntax element may indicate the third index. That is, a syntax element representing the L0 motion information and the L1 motion information may indicate the third index.
  • an index indicating the first reference picture among the reference pictures included in the L0, and the first of the reference pictures included in the L1 An index indicating a reference picture, a flag indicating the MVPL0 among the MVPL0 candidates included in the MVPL0 candidate list, and a flag indicating the MVPL1 among the MVPL1 candidates included in the MVPL1 candidate list may be received.
  • the decoding apparatus may receive a flag indicating whether to use a syntax element representing the L0 motion information and the L1 motion information through the SPS unit, the PPS unit, or the VPS unit, and the flag may transmit the L0 motion information and the L1 motion information.
  • the indicating syntax element for example, when the value of the flag is 1, the mode information may be received in units of slices.
  • the mode information may have a variable number of bits.
  • the mode information may have a variable number of bits according to the value of the mode information, a value having a high bit rate derived from the image among the values of the mode information having a small number of bits, and a rate derived from the image Low values can have a large number of bits.
  • the decoding apparatus derives the L0 motion information and the L1 motion information for the current block based on the syntax element (S620).
  • the decoding apparatus may derive the L0 motion information and the L1 motion information based on the syntax element.
  • the decoding apparatus may derive the first reference picture and the second reference picture based on the first index.
  • the L0 motion information may include an index of the first reference picture
  • the L1 motion information may include an index of the second reference picture.
  • the value of the first index may represent a combination of the index of the first reference picture and the index of the second reference picture
  • the decoding apparatus may be configured to perform the first reference picture in the combination of the reference pictures of L0.
  • the reference picture indicated by the index of may be derived as the first reference picture
  • the reference picture indicated by the index of the second reference picture in the combination among the reference pictures of L1 may be derived as the second reference picture.
  • the value of the index of the first reference picture and the value of the index of the second reference picture indicated by the value of the first index may be determined as shown in Table 4 above.
  • the decoding apparatus may derive the MVPL0 and the MVPL1 based on the second index.
  • the L0 motion information may include the MVPL0
  • the L1 motion information may include the MVPL1.
  • the value of the second index may represent a combination of a flag indicating the MVPL0 and a flag indicating the MVPL1
  • the decoding apparatus may include an MVPL0 candidate list including MVPL0 candidates and an MVPL1 candidate list including MVPL1 candidates in the current block.
  • the MVPL1 candidate indicated by the flag indicating the MVPL1 in the combination may be derived as the MVPL1.
  • the value of the flag of the MVPL0 and the value of the flag of the MVPL1 indicated by the value of the second index may be determined as shown in Table 7 above.
  • the decoding apparatus may determine the first reference picture, the second reference picture, the MVPL0, and the third index based on the third index.
  • the MVPL1 can be derived.
  • the L0 motion information may include an index of the first reference picture and the MVPL0
  • the L1 motion information may include an index of the second reference picture and the MVPL1.
  • the value of the third index may represent a combination of an index of the first reference picture, an index of the second reference picture, a flag indicating the MVPL0, and a flag indicating the MVPL1, and the decoding apparatus may determine the value of L0.
  • a reference picture indicated by the index of the first reference picture in the combination among the reference pictures may be derived as the first reference picture, and a reference indicated by the index of the second reference picture in the combination among the reference pictures of L1 A picture may be derived as the second reference picture.
  • the decoding apparatus may derive an MVPL0 candidate list including MVPL0 candidates and an MVPL1 candidate list including MVPL1 candidates based on motion vectors of neighboring blocks of the current block, wherein the decoding device includes the MVPL0 candidate list in the combination of the MVPL0 candidates in the MVPL0 candidate list.
  • the MVPL0 candidate indicated by the flag indicating MVPL0 may be derived as the MVPL0
  • the MVPL1 candidate indicated by the flag indicating the MVPL1 in the combination among the MVPL1 candidates in the MVPL1 candidate list may be derived as the MVPL1.
  • the value of the index of the first reference picture indicated by the value of the third index, the value of the index of the second reference picture, the value of the flag of MVPL0 and the value of the flag of MVPL1 are shown in Table 10 above. Can be determined.
  • the decoding apparatus derives a prediction sample of the current block based on the L0 motion information and the L1 motion information (S630).
  • the decoding apparatus may derive the prediction sample of the current block by performing pair prediction based on the L0 motion information and the L1 motion information.
  • the decoding apparatus may receive (acquire) motion vector difference L0 (MVDL0) information for the MVPL0 through the bitstream, and derive MVDL0 based on the obtained MVDL0 information. have.
  • the decoding apparatus may receive (acquire) motion vector difference L0 (MVDL1) information for the MVPL1 and derive MVDL1 based on the obtained MVDL1 information.
  • the decoding apparatus may derive a motion vector L0 (Motion Vector L0, MVL0) based on the MVPL0 and the MVDL0, and may derive a motion vector L1 (Motion Vector L1, MVL1) based on the MVPL1 and the MVDL1. .
  • the decoding apparatus may generate a prediction sample of the current block based on the MVL0 and the MVL1. In detail, the decoding apparatus may generate the prediction sample by performing pair prediction based on the L0 motion information including the first reference picture and the MVL0 and the L1 motion information including the second reference picture and the MVL1. have.
  • the decoding apparatus may directly use the prediction sample as a reconstruction sample according to a prediction mode, or generate a reconstruction sample by adding a residual sample to the prediction sample. If there is a residual sample for the current block, the decoding apparatus may receive information about the residual for the current block from the bitstream. The information about the residual may include transform coefficients regarding the residual sample. The decoding apparatus may derive the residual sample (or residual sample array) for the current block based on the residual information. The decoding apparatus may generate a reconstructed sample based on the prediction sample and the residual sample, and may derive a reconstructed block or a reconstructed picture based on the reconstructed sample. Thereafter, as described above, the decoding apparatus may apply an in-loop filtering procedure, such as a deblocking filtering and / or SAO procedure, to the reconstructed picture in order to improve subjective / objective picture quality as necessary.
  • an in-loop filtering procedure such as a deblocking filtering and / or SAO procedure
  • the L0 motion information and the L1 motion information of the current block can be derived. Coding efficiency can be improved.
  • the present invention by receiving a syntax element indicating the L0 motion information and the L1 motion information for the current block, it is possible to reduce the data amount of information for inter prediction of the current block, thereby improving the overall coding efficiency. have.
  • receiving information indicating whether to use the syntax element indicating the L0 motion information and the L1 motion information for the current block can be selectively applied to a part of the image, thereby improving the overall coding efficiency.
  • the above-described method according to the present invention may be implemented in software, and the encoding device and / or the decoding device according to the present invention may perform image processing of, for example, a TV, a computer, a smartphone, a set-top box, a display device, and the like. It can be included in the device.
  • the above-described method may be implemented as a module (process, function, etc.) for performing the above-described function.
  • the module may be stored in memory and executed by a processor.
  • the memory may be internal or external to the processor and may be coupled to the processor by various well known means.
  • the processor may include application-specific integrated circuits (ASICs), other chipsets, logic circuits, and / or data processing devices.
  • the memory may include read-only memory (ROM), random access memory (RAM), flash memory, memory card, storage medium and / or other storage device.

Abstract

Un procédé de décodage d'image mis œuvre par un dispositif de décodage, selon la présente invention, comprend : une étape consistant à dériver L0 et L1 ; une étape consistant à recevoir, par l'intermédiaire d'un train de bits, un élément de syntaxe indiquant des informations de mouvement L0 et des informations de mouvement L1 d'un bloc courant ; une étape consistant à dériver les informations de mouvement L0 et les informations de mouvement L1 du bloc courant sur la base de l'élément de syntaxe ; et une étape consistant à générer un échantillon de prédiction du bloc courant sur la base des informations de mouvement L0 et des informations de mouvement L1, les informations de mouvement L0 comprenant au moins l'un d'un prédicteur de vecteur de mouvement L0 et d'un indice d'une première image de référence du bloc courant, le prédicteur de vecteur de mouvement L0 et la première image de référence étant inclus dans L0, et les informations de mouvement L1 comprenant au moins l'un d'un prédicteur de vecteur de mouvement L1 et d'un indice d'une seconde image de référence du bloc courant, le prédicteur de vecteur de mouvement L1 et la seconde image de référence étant inclus dans L1.
PCT/KR2017/005671 2017-01-03 2017-05-31 Procédé et dispositif de décodage d'image dans un système de codage d'image WO2018128228A1 (fr)

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