WO2019225932A1 - Procédé et appareil de décodage d'image à l'aide de dmvr dans un système de codage d'images - Google Patents

Procédé et appareil de décodage d'image à l'aide de dmvr dans un système de codage d'images Download PDF

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WO2019225932A1
WO2019225932A1 PCT/KR2019/006037 KR2019006037W WO2019225932A1 WO 2019225932 A1 WO2019225932 A1 WO 2019225932A1 KR 2019006037 W KR2019006037 W KR 2019006037W WO 2019225932 A1 WO2019225932 A1 WO 2019225932A1
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motion information
picture
template
block
deriving
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PCT/KR2019/006037
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English (en)
Korean (ko)
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장형문
남정학
박내리
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엘지전자 주식회사
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    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04NPICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/10Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
    • H04N19/102Methods 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
    • H04N19/13Adaptive entropy coding, e.g. adaptive variable length coding [AVLC] or context adaptive binary arithmetic coding [CABAC]
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04NPICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/10Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
    • H04N19/102Methods 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
    • H04N19/132Sampling, masking or truncation of coding units, e.g. adaptive resampling, frame skipping, frame interpolation or high-frequency transform coefficient masking
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04NPICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/10Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
    • H04N19/169Methods 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
    • H04N19/17Methods 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
    • H04N19/176Methods 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
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04NPICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/10Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
    • H04N19/169Methods 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
    • H04N19/182Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding the unit being a pixel
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04NPICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/44Decoders specially adapted therefor, e.g. video decoders which are asymmetric with respect to the encoder

Definitions

  • the present invention relates to an image coding technique, and more particularly, to an image decoding method and apparatus using DMVR 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 technical problem of the present invention is to provide a method and apparatus for performing a DMVR.
  • Another object of the present invention is to provide a method and apparatus for performing a DMVR based on a template including reconstruction samples in a picture different from the current picture.
  • an image decoding method performed by a decoding apparatus.
  • the method includes deriving motion information of a current block, deriving scaled motion information by scaling the motion information based on a first distance and a second distance, based on the motion information and the scaled motion information.
  • a decoding apparatus for performing image decoding.
  • the decoding apparatus derives motion information of the current block, scales the motion information based on a first distance and a second distance, derives scaled motion information, and refines the based on the motion information and the scaled motion information.
  • a prediction unit for deriving refinement motion information by performing a process and performing prediction on the current block based on the refinement motion information, wherein the first distance is a POC (Picture Order Count) of a reference picture for the motion information; ), And the second distance is a difference between the POC of the collocated picture for the scaled motion information and the POC of the current picture.
  • a video encoding method performed by an encoding apparatus includes deriving motion information of a current block, deriving scaled motion information by scaling the motion information based on a first distance and a second distance, based on the motion information and the scaled motion information.
  • the first distance is a difference between a Picture Order Count (POC) of a reference picture for the motion information and a POC of a current picture
  • the second distance is a POC of the collocated picture for the scaled motion information and the It is characterized by a difference from the POC of the current picture.
  • POC Picture Order Count
  • a video encoding apparatus derives the motion information of the current block, scales the motion information based on a first distance and a second distance, derives scaled motion information, and refines the based on the motion information and the scaled motion information.
  • An entropy encoding for deriving refinement motion information by performing a process and encoding a picture information including prediction information for predicting the current block based on the refinement motion information, and information on prediction of the current block
  • a first distance is a difference between a picture order count (POC) of a reference picture for the motion information and a POC of a current picture
  • the second distance is a POC of the collocated picture for the scaled motion information and the second distance. It is characterized by a difference from the POC of the current picture.
  • the DMVR may be performed based on the motion information and the scaled motion information, and thus, the DMVR may be performed based on reconstructed samples of the current picture and other reference pictures, thereby preventing pipeline delay and generating overall coding.
  • the efficiency can be improved.
  • a template may be derived from a picture other than the current picture based on the motion information and the scaled motion information, and refinement or reordering may be performed based on the template.
  • DMVR based on reconstructed samples can prevent pipeline delay from occurring and improve 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 shows an example of performing a template matching method based DMVR.
  • FIG. 4 shows an example of performing a bidirectional matching method based DMVR.
  • 5 exemplarily shows a pipeline of a decoding apparatus.
  • FIG. 6 exemplarily illustrates a pipeline of a decoding apparatus to which a process of refining motion information using decoded peripheral samples is added.
  • FIG. 8 illustrates an example of performing a DMVR by deriving a reference block in a reference picture as a template.
  • FIG 9 illustrates another example of performing a DMVR by deriving a reference block in a reference picture as a template.
  • FIG. 10 illustrates an example of deriving motion information of the current block by using a reference block in a collocated picture indicated by scaled motion information as a template.
  • FIG. 11 illustrates an example of deriving motion information about the current block by using a reference block in a reference picture as a template.
  • FIG. 12 schematically illustrates an image encoding method by an encoding apparatus according to the present invention.
  • FIG. 13 schematically illustrates an encoding apparatus for performing an image encoding method according to the present invention.
  • FIG. 14 schematically illustrates an image decoding method by a decoding apparatus according to the present invention.
  • 16 exemplarily shows a structure diagram of a content streaming system to which the present invention is applied.
  • 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.
  • the present invention relates to video / image coding.
  • the methods / embodiments disclosed in the present invention may include a versatile video coding (VVC) standard, an essential video coding (ECC) standard, an AOMedia Video 1 (AV1) standard, a second generation of audio video coding standard (AVS2), or next-generation video.
  • VVC versatile video coding
  • ECC essential video coding
  • AV1 AOMedia Video 1
  • AVS2 second generation of audio video coding standard
  • next-generation video e.g., H.267, H.268, etc.
  • 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 splitter 105, a predictor 110, a residual processor 120, an entropy encoder 130, an adder 140, and a filter 150. ) And memory 160.
  • the residual processing unit 120 may include a subtraction unit 121, a conversion unit 122, a quantization unit 123, a reordering unit 124, an inverse quantization unit 125, and an inverse conversion unit 126.
  • the picture divider 105 may divide the input picture into at least one processing unit.
  • the processing unit may be called a coding unit (CU).
  • the coding unit may be recursively split from the largest coding unit (LCU) according to a quad-tree binary-tree (QTBT) structure.
  • LCU largest coding unit
  • QTBT quad-tree binary-tree
  • one coding unit may be divided into a plurality of coding units of a deeper depth based on a quad tree structure and / or a binary tree structure.
  • the quad tree structure may be applied first and the binary tree structure may be applied later.
  • the binary tree structure may be applied first.
  • the coding procedure according to the present invention may be performed based on the final coding unit that is no longer split.
  • 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 procedure may include a procedure of prediction, transform, and reconstruction, which will be described later.
  • the processing unit may include a coding unit (CU) prediction unit (PU) or a transform unit (TU).
  • the coding unit may be split from the largest coding unit (LCU) into coding units of deeper depths along the 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. If a smallest coding unit (SCU) is set, 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 unit partitioning from the coding unit and may be a unit 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, and may be a unit for deriving a transform coefficient and / or a unit 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 predicted 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 121 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 122 generates transform coefficients by transforming the residual sample in units of transform blocks.
  • the transform unit 122 may perform the transform 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 is configured to perform a discrete sine transform (DST) transform kernel.
  • the residual sample may be transformed using a discrete cosine transform (DCT) transform kernel.
  • DST discrete sine transform
  • DCT discrete cosine transform
  • the quantization unit 123 may quantize the transform coefficients to generate quantized transform coefficients.
  • the reordering unit 124 rearranges the quantized transform coefficients.
  • the reordering unit 124 may 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 124 has been described in a separate configuration, the reordering unit 124 may be part of the quantization unit 123.
  • the entropy encoding unit 130 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 130 may encode information necessary for video reconstruction other than the quantized transform coefficient (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 125 inverse quantizes the quantized values (quantized transform coefficients) in the quantization unit 123, and the inverse transformer 126 inverse transforms the inverse quantized values in the inverse quantization unit 125 to obtain a residual sample.
  • the adder 140 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 140 may be part of the predictor 110.
  • the adder 140 may be called a restoration unit or a restoration block generation unit.
  • the filter unit 150 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 150 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 reconstructed pictures (decoded pictures) or information necessary for encoding / decoding.
  • the reconstructed picture may be a reconstructed picture after the filtering process is completed by the filter unit 150.
  • 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 may include an entropy decoding unit 210, a residual processor 220, a predictor 230, an adder 240, a filter 250, and a memory 260. It may include.
  • the residual processor 220 may include a rearrangement unit 221, an inverse quantization unit 222, and an inverse transform unit 223.
  • the video decoding apparatus 200 may restore video in response to a process in which 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, for example, a coding unit, and in another example, a coding unit, a prediction unit, or a transform unit.
  • the coding unit may be split along the quad tree structure and / or binary tree structure from the largest coding unit.
  • the prediction unit and the transform unit may be further used in some cases, in which case the prediction block is a block derived or partitioned from the coding unit and may be a unit of sample prediction. At this point, the prediction unit may be divided into subblocks.
  • the transform unit may be divided along the quad tree structure from the coding unit, and may be a unit for deriving a transform coefficient or a unit 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 ( 221 may be input.
  • the reordering unit 221 may rearrange the quantized transform coefficients in a two-dimensional block form.
  • the reordering unit 221 may perform reordering in response to coefficient scanning performed by the encoding apparatus.
  • the rearrangement unit 221 has been described in a separate configuration, but the rearrangement unit 221 may be part of the inverse quantization unit 222.
  • the inverse quantization unit 222 may dequantize the quantized transform coefficients based on the (inverse) quantization parameter and output the transform coefficients.
  • information for deriving a quantization parameter may be signaled from the encoding apparatus.
  • the inverse transform unit 223 may inversely transform transform coefficients to derive residual samples.
  • the prediction unit 230 may perform prediction on the current block and generate a predicted block including prediction samples for the current block.
  • the unit of prediction performed by the prediction unit 230 may be a coding block, a transform block, or a prediction block.
  • the prediction unit 230 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 230 may derive the prediction sample for the current block based on the neighbor reference samples in the current picture.
  • the prediction unit 230 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 230 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 230 may apply any one of a skip mode, a merge mode, and an MVP mode to derive a prediction sample for the current block.
  • 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 prediction unit 230 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 230 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 230 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 230 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 240 may reconstruct the current block or the current picture by adding the residual sample and the predictive sample.
  • the adder 240 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 240 has been described in a separate configuration, the adder 240 may be part of the predictor 230. On the other hand, the adder 240 may be called a restoration unit or a restoration block generation unit.
  • the filter unit 250 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 260 may store reconstructed pictures (decoded pictures) or information necessary for decoding.
  • the reconstructed picture may be a reconstructed picture after the filtering process is completed by the filter unit 250.
  • the memory 260 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 260 may output the reconstructed picture in an output order.
  • a process of predicting motion information of the current block may be performed as described above, and the process is essentially applied to reduce the amount of bits for representing the motion information and the residual signal. It is becoming.
  • a merge mode for deriving motion information from neighboring blocks of the current block and saving information on the motion vector and the reference block of the current block is an example of a process of predicting the motion information.
  • a decoder-side motion vector refinement (DMVR) technique for improving accuracy by refining prediction information from limitedly derived motion information as a method of deriving motion information of the current block is proposed.
  • DMVR decoder-side motion vector refinement
  • the conventional inter prediction only limited derived motion information may be used.
  • the DMVR since the motion of the current block is predicted using only the motion vector of the neighboring block without a motion vector difference (MVD), there may be a limit in improving the accuracy of inter prediction.
  • the DMVR since the DMVR is proposed, the DMVR may be a bi-lateral matching method or a template matching method based DMVR.
  • DMVR performed using the template matching method may represent a method of deriving refined motion information based on sample values of neighboring samples of the current block.
  • the peripheral samples of the current block may include left peripheral samples and upper peripheral samples that may be referenced in the current block.
  • an arbitrary peripheral area of the current block may be set as a template of the current block, and the current in the search range using a template of the same type as the template of the current block on a reference picture.
  • the motion information search of the block may be performed.
  • the left neighboring samples and the upper neighboring samples of the current block may already be decoded at the decoding time of the current block, and thus may be used in the motion estimation process in the decoding apparatus, so that the left neighboring samples And the upper peripheral samples may be included in a template of the current block.
  • the template of the current block may be a specific area including the left peripheral samples and the upper peripheral samples.
  • a template having a minimum difference from a template of the current block among templates of reference blocks within a search range of a reference picture ie, a template most similar to a template of the current block
  • Motion information indicating a reference block of the derived template may be derived as refined motion information of the current block.
  • the difference may be called cost.
  • the cost may be derived as the sum of the absolute values of the differences between the corresponding samples of the template of the current block and the template of the reference block.
  • the cost function for deriving the MV of the current block may be represented by the following equation. That is, the cost may be derived based on the following equation.
  • i and j represent positions (i, j) of samples in a block
  • Cost distortion represents the cost
  • Temp ref represents a sample value of a template of a reference block
  • Temp cur represents a sample value of a template of the current block.
  • the difference between corresponding samples between the template of the reference block and the template of the current block may be accumulated, and the accumulation of the difference may be used as a cost function for deriving the motion vector of the current block.
  • the search range is centered on the position indicated by the motion information derived with respect to the current block, and may be derived as a quadrangular area having a height and a width of N.
  • N may be 2, 4, or 5 integer pels.
  • the derived motion information may indicate motion information or motion information candidate (eg, merge candidate or MVP candidate) of the current block.
  • the bidirectional matching method based DMVR may be performed as follows.
  • FIG. 4 shows an example of performing a bidirectional matching method based DMVR.
  • the bidirectional matching method based DMVR may be performed when bi-prediction is applied to the current block. That is, when the derived motion information of the current block is bi-predictive motion information, the bidirectional matching method based DMVR may be applied.
  • the bi-prediction motion information may include L0 motion information and L1 motion information.
  • the L0 motion information may include an L0 reference picture index and a motion vector L0 (Motion Vector L0, MVL0) indicating an L0 reference picture included in the reference picture list L0 (List 0, L0) for the current block.
  • the L1 motion information may include an L1 reference picture index and an MVL1 indicating the L1 reference picture included in the reference picture list L1 (List 1, L1) for the current block.
  • motion information including only L0 motion information or L1 motion information may be referred to as unipredictive motion information.
  • LO prediction when performing inter prediction based on L0 motion information, it may be called LO prediction, and when performing inter prediction based on L1 motion information, it may be called L1 prediction.
  • bi-prediction when inter prediction is performed based on the L0 motion information and the L1 motion information, it may be referred to as bi-prediction.
  • the encoding device / decoding device may derive the L0 reference block indicated by the L0 motion information included in the motion information and the L1 reference block indicated by the L1 motion information, and are based on the L0 reference block and the L1 reference block.
  • a target block can be derived.
  • the encoding device / decoding device may derive the target block by averaging the L0 reference block and the L1 reference block. That is, the decoding apparatus may configure the target block by deriving an average between the L0 reference block and the corresponding samples of the L1 reference block as samples of the target block.
  • the encoding device / decoding device is a refined L0 reference block having the smallest SAD with the target block among the L0 reference blocks included in the peripheral area of the L0 reference block and the L1 reference block included in the peripheral area of the L1 reference block.
  • a refined L1 reference block having the smallest SAD with the target block may be derived.
  • Refined L0 motion information indicating the refined L0 reference block and refined L1 motion information indicating the refined L1 reference block may be derived as refined motion information. That is, the refined motion information may include the refined L0 motion information and the refined L1 motion information.
  • the peripheral area of the L0 reference block may be referred to as a search range for L0
  • the peripheral area of the L1 reference block may be referred to as a search range for L1.
  • the search range for the L0 may be derived as a quadrangular region having a height and a width of N, centered on the location indicated by the L0 motion information
  • the search range for the L1 may be the L1 motion information. It can be derived from a rectangular area having a height and width N, centered on the position indicated by.
  • N may be 2, 4, or 5 integer pels.
  • the DMVR may be applied to motion information (ie, selected motion information) of the current block or merge candidate or MVP candidate of the current block.
  • motion information ie, selected motion information
  • a refine merge candidate or a refined MVP candidate including the refinement motion information may be derived, and the derived refine merge candidate or the refined MVP candidate may be derived from the current candidate. It may be added to the motion information candidate list (ie, the merge candidate list or the MVP candidate list) of the block.
  • the decoding apparatus may perform a decoding process in parallel. For example, the decoding apparatus may decode coding related information about a first coding block in a bitstream based on CABAC, perform a subsequent decoding process on the first coding block, and in parallel A process of decoding the coding related information about the second coding block may be performed.
  • the pipeline of the decoding apparatus may be changed as follows.
  • FIG. 6 exemplarily illustrates a pipeline of a decoding apparatus to which a process of refining motion information using decoded peripheral samples is added.
  • the derivation of motion information of a next coding block may be delayed until a decoded neighboring sample is available, and thus, the entire decoding process of the next coding block may be delayed.
  • the delay may be referred to as a pipeline delay.
  • the motion information derivation process for the second coding block may be performed.
  • a pipeline delay may not be possible because a fetch request cannot be made in advance. 6 described above exemplarily illustrates the pipeline delay described above.
  • the present invention proposes a method of using only the upper template without using the left template of the current block in the DMVR using the template. That is, the present invention proposes a method of performing the DMVR based on a template including only surrounding samples located above.
  • the upper template that is, the upper peripheral samples of the current block
  • the current block is decoded long before the current block is decoded in the decoding process, even if used as a template for the current block, there is no problem of breaking the pipeline. Can be.
  • the template of the current block may include upper peripheral samples of the current block.
  • the size of the template of the current block may be set to various sizes in consideration of the capacity of the line buffer (linebuffer). For example, when the size of the current block is NxN size and the x component of the top-left sample position of the current block is 0 and the y component is 0, as shown in FIG.
  • the template of the current block includes an upper left sample of (-N, -M) coordinates and may be derived as an area having a size of 2N ⁇ M.
  • the template of the current block may include a top left sample of (0, -M) coordinates, and may be derived as an area having a size of 2N ⁇ M.
  • the x component of the top-left sample position of the current block is 0 and y component is 0, shown in (c) of FIG.
  • the template of the current block may include a top left sample of (0, -M) coordinates, and may be derived as an area having a size of NxM size.
  • the template of the current block may include a top left sample of (-N, -M) coordinates, and may be derived as an area having a size of 3N ⁇ M.
  • the present invention proposes a method of using a sample already decoded in a reference picture as a template, without using the decoded neighboring samples of the current block as a template. That is, a method of using a decoded reference sample in a reference picture other than the current picture as a template may be proposed.
  • the problem that the pipeline delay occurs may occur because a decoded neighboring sample of the current block in the current picture is used as a template. Therefore, the template matching method can be used while solving the problem of the above-described pipeline delay through the proposed embodiment, and even in the single prediction, that is, even when the motion information of the current block is the single prediction motion information, Bi-lateral matching effect can be used.
  • FIG. 8 illustrates an example of performing a DMVR by deriving a reference block in a reference picture as a template.
  • a reference block in a reference picture indicated by a motion vector of a selected motion information candidate as a template may be proposed.
  • motion information of the current block among motion information candidates of the motion information candidate list for the current block may be derived, and a reference block indicated by the motion information may be derived from the current block. Can be derived from a template. Thereafter, the motion vector of the motion information of the current block may be scaled based on a distance ratio between a first distance and a second distance, and a search range in a collocated picture based on the scaled motion vector. May be derived, and the refinement process may be performed within the search range. That is, a motion vector indicating a reference block having a minimum cost with the template among the reference blocks within the search range may be derived as a refined motion vector.
  • the cost may be a difference between the template and the reference block, and the difference may be the above-described SAD or mean-reduced SAD.
  • the search range may be derived as a quadrangular region having a height and a width N centered on a position indicated by the scaled vector.
  • N may be 2, 4, or 5 integer pels.
  • the first distance may be a difference between a picture order count (POC) of the reference picture and a POC of the current picture
  • the second distance may be a difference between a POC of the collocated picture and a POC of the current picture. .
  • POC picture order count
  • a reference block of a reference picture is a template may be proposed.
  • FIG. 9 illustrates another example of performing a DMVR by deriving a reference block in a reference picture as a template.
  • a motion vector of a selected motion information candidate is scaled to the collocated picture, and a reference block indicated by the scaled motion vector of the collocated picture is derived as a template.
  • motion information of the current block among motion information candidates of the motion information candidate list for the current block may be derived, and the motion vector of the motion information may be formed of a first distance and a first distance.
  • the reference block in the collocated picture indicated by the scaled motion vector may be derived as a template of the current block.
  • a search range within the reference picture may be derived based on the motion vector of the motion information of the current block, and a refinement process may be performed within the search range. That is, a motion vector indicating a reference block having a minimum cost with the template among the reference blocks within the search range may be derived as a refined motion vector.
  • the cost may be a difference between the template and the reference block, and the difference may be the above-described SAD or mean-reduced SAD.
  • the search range may be derived as a quadrangular region having a height and a width of N, centered on the position indicated by the motion vector of the motion information.
  • N may be 2, 4, or 5 integer pels.
  • the first distance may be a difference between a picture order count (POC) of the reference picture and a POC of the current picture
  • the second distance may be a difference between a POC of the collocated picture and a POC of the current picture. .
  • POC picture order count
  • the present invention is an embodiment of using a sample already decoded in the reference picture as a template, but performing candidate reordering using only the cost calculated based on the template without the MV refinement process on the decoder side, Alternatively, an embodiment of selecting a motion information candidate having a minimum cost as the motion information of the current block without candidate index signaling for the current block.
  • FIG. 10 illustrates an example of deriving motion information of the current block by using a reference block in a collocated picture indicated by scaled motion information as a template.
  • a motion vector of a motion information candidate of a motion information candidate list for a current block may be scaled to correspond to a collocated picture, and is referred to in a collocated picture indicated by the scaled motion vector.
  • the block may be set as a template.
  • the motion vector of the motion information candidate may be scaled based on a distance ratio between a first distance and a second distance, and a reference block in the collocated picture indicated by the scaled motion vector may be derived as the template. .
  • the first distance may be a difference between a picture order count (POC) of the reference picture and a POC of the current picture
  • the second distance may be a difference between a POC of the collocated picture and a POC of the current picture.
  • a target template corresponding to the current block in the reference picture may be set based on the motion information of the motion information candidate. That is, a reference block in a reference picture indicated by the motion information candidate may be derived as a target template.
  • the cost for the motion information candidate may be calculated through SAD or Mean-reduced SAD, which is a difference between the target template located in the reference picture and the template located in the collocated picture. That is, the cost between the target template and the template in the reference picture may be calculated, wherein the cost may be a difference between the target template and the template, and the difference may be the above-described SAD or Mean-Reduced SAD. Can be.
  • the costs of the motion information candidates included in the motion information candidate list may be calculated, and the motion information candidates may be reordered based on the cost. Thereafter, index information for the reordered motion information candidates may be signaled, and a motion information candidate indicated by the index information among the motion information candidates may be selected. For example, the motion information candidates may be reordered in order of decreasing cost.
  • a motion information candidate having a minimum cost among the motion information candidates may be selected as motion information for the current block without signaling index information.
  • a motion vector of the selected motion information candidate that is, a motion vector indicating a template for the selected motion information candidate, may be derived as motion information for the current block.
  • FIG. 11 illustrates an example of deriving motion information about the current block by using a reference block in a reference picture as a template.
  • a template corresponding to the current block in the reference picture may be set based on the motion information of the motion information candidate. That is, the reference block in the reference picture indicated by the motion information candidate of the motion information candidate list for the current block may be derived as a template.
  • the motion vector of the motion information candidate may be scaled to correspond to the collocated picture, and a reference block in the collocated picture indicated by the scaled motion vector may be set as a target template.
  • the motion vector of the motion information candidate may be scaled based on a distance ratio between a first distance and a second distance, and a reference block in the collocated picture indicated by the scaled motion vector may be derived as the target template.
  • the first distance may be a difference between a picture order count (POC) of the reference picture and a POC of the current picture
  • the second distance may be a difference between a POC of the collocated picture and a POC of the current picture.
  • the cost for the motion information candidate may be calculated through SAD or Mean-reduced SAD, which is a difference between the template located in the reference picture and the target template located in the collocated picture. That is, the cost between the template in the reference picture and the target template may be calculated, wherein the cost may be a difference between the template and the reference block, and the difference may be the above-described SAD or Mean-Reduced SAD. have.
  • the costs of the motion information candidates included in the motion information candidate list may be calculated, and the motion information candidates may be reordered based on the cost. Thereafter, index information for the reordered motion information candidates may be signaled, and a motion information candidate indicated by the index information among the motion information candidates may be selected. For example, the motion information candidates may be reordered in order of decreasing cost.
  • a motion information candidate having a minimum cost among the motion information candidates may be selected as motion information for the current block without signaling index information.
  • a motion vector obtained by scaling the motion vector of the selected motion information candidate with the collocated picture that is, a motion vector indicating a target template for the selected motion information candidate may be derived as motion information for the current block.
  • control syntax information indicating whether to perform DMVR
  • the control syntax information may be signaled through a high level, and based on the control syntax information, for example, a slice, a tile, a picture in a corresponding region (eg, a slice, a tile, a picture) It may be determined whether to perform DMVR.
  • the high level may indicate a video parameter set (VPS), a sequence parameter set (SPS), a picture parameter set (PPS), a slice segment header, a coding unit header, or the like.
  • the high level may also be referred to as a high level syntax (HLS).
  • control syntax information may be signaled in units of a prediction unit, and whether or not the prediction unit performs the DMVR may be determined based on the control syntax information.
  • control syntax information may be signaled as shown in the following table.
  • Refinement_control_syntax may indicate a syntax element for the control syntax information.
  • a region may be selected based on syntax information transmitted from a high level syntax, and signaling syntax information controlling to perform refinement in the selected region.
  • a solution may be proposed.
  • control syntax information indicating whether a DMVR is applied may be signaled, and when the control syntax information indicates that the DMVR is applied, region syntax information indicating a region to which the DMVR is applied may be signaled.
  • control syntax information and the region syntax information may be signaled as shown in the following table.
  • Refinement_control_syntax may indicate a syntax element for the control syntax information
  • Refinement_region_syntax may indicate a syntax element for the region syntax information
  • control syntax information indicating whether the DMVR is applied may be signaled, and when the control syntax information indicates that the DMVR is applied, the Precision Syntax information indicating the Precision of the region to which the DMVR is applied may be signaled.
  • the precision of the region may be derived based on the syntax syntax information. For example, the precision may be derived as 1/8, 1/4, 1/2, 1, 2, 4, 8, 16, 32, 64 or 128. In this case, for example, a refinement process may be performed on the position of the precision unit within the search range.
  • control syntax information and the precision syntax information may be signaled as shown in the following table.
  • Refinement_control_syntax may indicate a syntax element for the control syntax information
  • Refinement_precision_syntax may indicate a syntax element for the precision syntax information
  • a method of signaling direction syntax information for selectively determining a refinement direction may be proposed.
  • a method of selectively determining a prediction direction in which a refinement process is performed among L0, L1, and Bi based on the direction syntax information, and signaling a controlling syntax to perform refinement only on the corresponding motion information may be proposed.
  • control syntax information indicating whether a DMVR is applied may be signaled, and when the control syntax information indicates that the DMVR is applied, direction syntax information indicating a prediction direction to which the DMVR is applied may be signaled.
  • the direction syntax information may indicate one of L0 prediction, L1 prediction, and / or pair prediction.
  • DMVR may be performed on motion information or motion information candidate of the current block which is L0 motion information.
  • L1 prediction DMVR may be performed on motion information or motion information candidate of the current block that is L1 motion information.
  • the DMVR may be performed on the motion information or the motion information candidate of the current block which is the pair prediction motion information.
  • control syntax information and the direction syntax information may be signaled as shown in the following table.
  • Refinement_control_syntax may indicate a syntax element for the control syntax information
  • Refinement_direction_syntax may indicate a syntax element for the direction syntax information
  • FIG. 12 schematically illustrates an image encoding method by an encoding apparatus according to the present invention.
  • the method disclosed in FIG. 12 may be performed by the encoding apparatus disclosed in FIG. 1.
  • S1200 to S1230 of FIG. 12 may be performed by the prediction unit of the encoding apparatus
  • S1240 may be performed by the entropy encoding unit of the encoding apparatus.
  • a process of deriving a residual sample for the current block based on the original sample and the prediction sample for the current block may be performed by a subtractor of the encoding apparatus
  • the generating of the information about the residual on the basis of the current block may be performed by a converter of the encoding apparatus, and may include image information including information about the residual and information about prediction of the current block.
  • the encoding process may be performed by an entropy encoding unit of the encoding apparatus.
  • the encoding apparatus derives motion information of the current block (S1200).
  • the encoding apparatus may derive the motion information of the current block.
  • the motion information may include a reference picture index and / or a motion vector.
  • the encoding apparatus may perform inter prediction on the current block.
  • the encoding apparatus may construct a motion information candidate list based on neighboring blocks, select a specific motion information candidate from among motion information candidates of the motion information candidate list, and use the selected motion information candidate as motion information for the current block. Can be derived.
  • the encoding apparatus may generate index information indicating the selected motion information.
  • Information on the prediction of the current block may include the index information.
  • the index information may be referred to as a merge index.
  • the encoding apparatus may select a specific motion information candidate from among motion information candidates of the motion information candidate list, derive the selected motion information candidate as a motion vector predictor (MVP) for the current block, wherein the MVP and Based on the motion vector difference (MVD) can be derived as the motion information for the current block.
  • MVP motion vector predictor
  • the encoding apparatus may generate index information indicating the selected motion information, a reference picture index indicating the reference picture for the current block, and / or the MVD.
  • Information about the prediction of the current block may include the index information, the reference picture index, and / or the MVD.
  • the index information may be referred to as an MVP index.
  • the encoding apparatus may derive costs for motion information candidates of the motion information candidate list and reorder the motion information candidates based on the costs to generate a modified motion information candidate list. Can be derived.
  • the encoding apparatus may select a specific motion information candidate from the motion information candidates of the modified motion information candidate list, and derive the selected motion information candidate as motion information for the current block.
  • the encoding apparatus may generate index information indicating the selected motion information.
  • Information on the prediction of the current block may include the index information.
  • the cost for the motion information candidate may be derived as follows.
  • the encoding apparatus may derive the reference block in the reference picture indicated by the motion information candidate as a template, derive the reference block in the collocated picture indicated by the scaled motion information as the target template, and A cost for the motion information candidate may be derived based on the target template.
  • the cost may be derived as SAD or Mean-Reduced SAD between the template and the target template.
  • the scaled motion information may be derived by scaling the motion information based on a distance ratio between a first distance and a second distance.
  • the first distance may be a difference between a picture order count (POC) of a reference picture for the motion information and a POC of a current picture
  • the second distance is a POC of the collocated picture for the scaled motion information and the It may be a difference from the POC of the current picture.
  • POC picture order count
  • the encoding apparatus may derive the reference block in the reference picture indicated by the motion information candidate as the target template, derive the reference block in the collocated picture indicated by the scaled motion information as the template, and A cost for the motion information candidate may be derived based on a target template and the template.
  • the cost may be derived as SAD or Mean-Reduced SAD between the target template and the template.
  • the scaled motion information may be derived by scaling the motion information based on a distance ratio between a first distance and a second distance.
  • the first distance may be a difference between a picture order count (POC) of a reference picture for the motion information and a POC of a current picture
  • the second distance is a POC of the collocated picture for the scaled motion information and the It may be a difference from the POC of the current picture.
  • POC picture order count
  • the encoding apparatus may derive the costs for the motion information candidates of the motion information candidate list and may derive the motion information for the current block based on the motion information candidate having the lowest cost. In this case, index information indicating one of the motion information candidates may not be signaled.
  • the cost for the motion information candidate may be derived as follows.
  • the encoding apparatus may derive the reference block in the reference picture indicated by the motion information candidate as a template, derive the reference block in the collocated picture indicated by the scaled motion information as the target template, and A cost for the motion information candidate may be derived based on the target template.
  • the cost may be derived as SAD or Mean-Reduced SAD between the template and the target template.
  • the scaled motion information may be derived by scaling the motion information based on a distance ratio between a first distance and a second distance.
  • the first distance may be a difference between a picture order count (POC) of a reference picture for the motion information and a POC of a current picture
  • the second distance is a POC of the collocated picture for the scaled motion information and the It may be a difference from the POC of the current picture.
  • the scaled motion information of the motion information candidate having the lowest cost may be derived as the motion information of the current block.
  • the encoding apparatus may derive the reference block in the reference picture indicated by the motion information candidate as the target template, derive the reference block in the collocated picture indicated by the scaled motion information as the template, and A cost for the motion information candidate may be derived based on a target template and the template.
  • the cost may be derived as SAD or Mean-Reduced SAD between the target template and the template.
  • the scaled motion information may be derived by scaling the motion information based on a distance ratio between a first distance and a second distance.
  • the first distance may be a difference between a picture order count (POC) of a reference picture for the motion information and a POC of a current picture
  • the second distance is a POC of the collocated picture for the scaled motion information and the It may be a difference from the POC of the current picture.
  • the motion information candidate having the lowest cost may be derived as the motion information of the current block.
  • the encoding apparatus derives scaled motion information by scaling the motion information based on a first distance and a second distance (S1210).
  • the encoding apparatus may derive scaled motion information by scaling the motion information based on a distance ratio between the first distance and the second distance.
  • the first distance may be a difference between a picture order count (POC) of a reference picture for the motion information and a POC of a current picture
  • the second distance is a POC of the collocated picture for the scaled motion information and the It may be a difference from the POC of the current picture. That is, the motion information for the reference picture may be scaled to the collocated picture.
  • POC picture order count
  • the scaled motion vector of the scaled motion information is derived by multiplying the motion vector of the motion information by b / a.
  • the motion information may include a reference picture index indicating the reference picture
  • the scaled motion information may include a reference picture index indicating the collocated picture.
  • the encoding apparatus derives refined motion information by performing a refinement process based on the motion information and the scaled motion information (S1220).
  • the encoding apparatus may derive a template, derive a reference block having the lowest cost with the template among the reference blocks within the search range, and derive the motion information indicating the reference block as the refined motion information. .
  • the encoding apparatus may derive a reference block in the reference picture indicated by the motion information as a template, and select a reference block having the smallest cost with the template among the reference blocks in the search range.
  • the motion information indicating the reference block may be derived as the refined motion information.
  • the search range may be a rectangular-shaped area having a height and a width of N with respect to the position in the collocated picture indicated by the scaled motion information.
  • N may be 2, 4, or 5 integer pels.
  • the cost of the template and the reference block within the search range may be a sum of absolute differences (SAD) or a mean-reduced SAD between the template and the reference block. When the cost is the SAD between the template and the reference block, the cost may be derived based on the following equation.
  • Temp ref (i, j) may represent a reconstruction sample of (i, j) coordinates in the template
  • Block col (i, j) may represent a reconstruction sample of (i, j) coordinates in the reference block.
  • the encoding apparatus may derive a reference block in the collocated picture indicated by the scaled motion information as a template, and the cost of the reference block among the reference blocks in the search range is increased.
  • the smallest reference block may be derived, and motion information indicating the reference block may be derived as the refined motion information.
  • the search range may be a rectangular area having a height and a width of N with respect to the position in the reference picture indicated by the motion information.
  • N may be 2, 4, or 5 integer pels.
  • the cost of the template and the reference block within the search range may be a sum of absolute differences (SAD) or a mean-reduced SAD between the template and the reference block. When the cost is the SAD between the template and the reference block, the cost may be derived based on the following equation.
  • Temp col (i, j) may represent a reconstruction sample of (i, j) coordinates in the template
  • Block ref (i, j) may represent a reconstruction sample of (i, j) coordinates in the reference block.
  • the encoding apparatus performs prediction on the current block based on the refinement motion information in operation S1230.
  • the encoding apparatus may derive the prediction sample of the current block by performing prediction on the current block based on the refined motion information.
  • a prediction block of the current block may be derived based on the refinement motion information, and a reconstruction block may be derived based on the prediction block.
  • the encoding apparatus may derive a reference block in a reference picture (or collocated picture) based on the refine motion information.
  • the refined motion information may include a refined motion vector and a reference picture index.
  • the encoding apparatus encodes image information including information on prediction of the current block (S1240).
  • the encoding apparatus may encode and output the video information including the information on the prediction of the current block in the form of a bitstream.
  • the bitstream may be transmitted to a decoding apparatus via a network or a storage medium.
  • the encoding apparatus may determine the prediction mode of the current block, and generate information indicating the prediction mode.
  • the information about the prediction may include index information indicating the selected motion information candidate among the motion information candidates of the motion information candidate list.
  • the information on the prediction of the current block may include a merge flag indicating whether a merge mode is applied to the current block.
  • the encoding apparatus may generate information about the residual based on the residual sample.
  • the image information may include information about the residual, and the information about the residual may include transform coefficients related to the residual sample.
  • the encoding device may encode the information about the residual and output the encoded information about the residual.
  • the bitstream may be transmitted to a decoding apparatus via a network or a storage medium.
  • the encoding apparatus may generate control syntax information indicating whether a refinement process is applied to a current region including the current block.
  • the current region may be one of a slice, a tile, and a picture.
  • the encoding apparatus may generate region syntax information indicating a region to which the refinement process is applied.
  • the encoding apparatus may generate the precision syntax information indicating the precision.
  • the precision syntax information may indicate 1/8, 1/4, 1/2, 1, 2, 4, 8, 16, 32, 64, or 128.
  • the encoding apparatus may generate direction syntax information indicating a prediction direction in which the refinement process is performed.
  • the direction syntax information may indicate one of L0 prediction, L1 prediction, and / or pair prediction.
  • the control syntax information, the region syntax information, the precision syntax information and / or the direction syntax information may include a video parameter set (VPS), a sequence parameter set (SPS), a picture parameter set (PPS), and a slice segment header. ) Or via a coding unit header.
  • the image information may include the control syntax information, the region syntax information, the precision syntax information, and / or the direction syntax information.
  • FIG. 13 schematically illustrates an encoding apparatus for performing an image encoding method according to the present invention.
  • the method disclosed in FIG. 12 may be performed by the encoding apparatus disclosed in FIG. 13.
  • the prediction unit of the encoding apparatus of FIG. 13 may perform S1200 to S1230 of FIG. 12, and the entropy encoding unit of the encoding apparatus of FIG. 13 may perform S1240 of FIG. 12.
  • the process of deriving the residual sample for the current block based on the original sample and the prediction sample for the current block may be performed by the subtractor of the encoding apparatus of FIG. 13.
  • the generating of the information about the residual for the current block based on the residual sample may be performed by the converter of the encoding apparatus of FIG. 13, and the encoding of the residual information may be performed in FIG. 13. May be performed by an entropy encoding unit of the encoding apparatus.
  • FIG. 14 schematically illustrates an image decoding method by a decoding apparatus according to the present invention.
  • the method disclosed in FIG. 14 may be performed by the decoding apparatus disclosed in FIG. 2.
  • S1400 to S1430 of FIG. 14 may be performed by the prediction unit of the decoding apparatus.
  • a process of obtaining information on prediction and / or residual information of a current block through a bitstream may be performed by an entropy decoding unit of the decoding apparatus.
  • the process of deriving the residual sample for the current block may be performed by an inverse transform unit of the decoding apparatus, and the process of generating a reconstructed picture based on the prediction sample and the residual sample of the current block may be performed. It may be performed by an adder of the decoding apparatus.
  • the decoding apparatus derives motion information of the current block (S1400).
  • the decoding apparatus may derive the motion information of the current block.
  • the motion information may include a reference picture index and / or a motion vector.
  • the decoding apparatus may perform inter prediction on the current block.
  • the decoding apparatus may construct a motion information candidate list based on neighboring blocks, select a specific motion information candidate from among motion information candidates of the motion information candidate list, and use the selected motion information candidate as motion information for the current block. Can be derived.
  • the decoding apparatus may obtain index information through the bitstream, and may derive the motion information candidate indicated by the index information among the motion information candidates of the motion information candidate list as the motion information for the current block. .
  • the decoding apparatus may obtain index information and a motion vector difference (MVD) through a bitstream, and among the motion information candidates of the motion information candidate list, the motion information candidate indicated by the index information may be selected as an MVP for the current block.
  • Motion Vector Predictor Motion Vector Predictor
  • the motion information candidate list may indicate a merge candidate list or an MVP candidate list
  • the motion candidate may indicate a merge candidate or an MVP candidate.
  • the index information may indicate a merge index or an MVP index.
  • the decoding apparatus may derive costs for motion information candidates of the motion information candidate list and reorder the motion information candidates based on the costs to generate a modified motion information candidate list. Can be derived.
  • the decoding apparatus may obtain index information through the bitstream, and may derive the motion information candidate indicated by the index information among the motion information candidates of the modified motion information candidate list as the motion information for the current block.
  • the cost for the motion information candidate may be derived as follows.
  • the decoding apparatus may derive the reference block in the reference picture indicated by the motion information candidate as a template, derive the reference block in the collocated picture indicated by the scaled motion information as the target template, and A cost for the motion information candidate may be derived based on the target template.
  • the cost may be derived as SAD or Mean-Reduced SAD between the template and the target template.
  • the scaled motion information may be derived by scaling the motion information based on a distance ratio between a first distance and a second distance.
  • the first distance may be a difference between a picture order count (POC) of a reference picture for the motion information and a POC of a current picture
  • the second distance is a POC of the collocated picture for the scaled motion information and the It may be a difference from the POC of the current picture.
  • POC picture order count
  • the decoding apparatus may derive the reference block in the reference picture indicated by the motion information candidate as the target template, derive the reference block in the collocated picture indicated by the scaled motion information as the template, and A cost for the motion information candidate may be derived based on a target template and the template.
  • the cost may be derived as SAD or Mean-Reduced SAD between the target template and the template.
  • the scaled motion information may be derived by scaling the motion information based on a distance ratio between a first distance and a second distance.
  • the first distance may be a difference between a picture order count (POC) of a reference picture for the motion information and a POC of a current picture
  • the second distance is a POC of the collocated picture for the scaled motion information and the It may be a difference from the POC of the current picture.
  • POC picture order count
  • the decoding apparatus may derive the costs for the motion information candidates of the motion information candidate list and may derive the motion information for the current block based on the motion information candidate having the lowest cost. In this case, index information indicating one of the motion information candidates may not be signaled.
  • the cost for the motion information candidate may be derived as follows.
  • the decoding apparatus may derive the reference block in the reference picture indicated by the motion information candidate as a template, derive the reference block in the collocated picture indicated by the scaled motion information as the target template, and A cost for the motion information candidate may be derived based on the target template.
  • the cost may be derived as SAD or Mean-Reduced SAD between the template and the target template.
  • the scaled motion information may be derived by scaling the motion information based on a distance ratio between a first distance and a second distance.
  • the first distance may be a difference between a picture order count (POC) of a reference picture for the motion information and a POC of a current picture
  • the second distance is a POC of the collocated picture for the scaled motion information and the It may be a difference from the POC of the current picture.
  • the scaled motion information of the motion information candidate having the lowest cost may be derived as the motion information of the current block.
  • the decoding apparatus may derive the reference block in the reference picture indicated by the motion information candidate as the target template, derive the reference block in the collocated picture indicated by the scaled motion information as the template, and A cost for the motion information candidate may be derived based on a target template and the template.
  • the cost may be derived as SAD or Mean-Reduced SAD between the target template and the template.
  • the scaled motion information may be derived by scaling the motion information based on a distance ratio between a first distance and a second distance.
  • the first distance may be a difference between a picture order count (POC) of a reference picture for the motion information and a POC of a current picture
  • the second distance is a POC of the collocated picture for the scaled motion information and the It may be a difference from the POC of the current picture.
  • the motion information candidate having the lowest cost may be derived as the motion information of the current block.
  • the decoding apparatus derives scaled motion information by scaling the motion information based on a first distance and a second distance (S1410).
  • the decoding apparatus may derive the scaled motion information by scaling the motion information based on a distance ratio between the first distance and the second distance.
  • the first distance may be a difference between a picture order count (POC) of a reference picture for the motion information and a POC of a current picture
  • the second distance is a POC of the collocated picture for the scaled motion information and the It may be a difference from the POC of the current picture. That is, the motion information for the reference picture may be scaled to the collocated picture.
  • POC picture order count
  • the scaled motion vector of the scaled motion information is derived by multiplying the motion vector of the motion information by b / a.
  • the motion information may include a reference picture index indicating the reference picture
  • the scaled motion information may include a reference picture index indicating the collocated picture.
  • the decoding apparatus derives refined motion information by performing a refinement process based on the motion information and the scaled motion information (S1420).
  • the decoding apparatus may derive a template, derive a reference block having the smallest cost with the template among the reference blocks within the search range, and derive motion information indicating the reference block as the refined motion information. .
  • the decoding apparatus may derive a reference block in the reference picture indicated by the motion information as a template, and select a reference block having the lowest cost from the template among the reference blocks in the search range.
  • the motion information indicating the reference block may be derived as the refined motion information.
  • the search range may be a rectangular-shaped area having a height and a width of N with respect to the position in the collocated picture indicated by the scaled motion information.
  • N may be 2, 4, or 5 integer pels.
  • the cost of the template and the reference block within the search range may be a sum of absolute differences (SAD) or a mean-reduced SAD between the template and the reference block. When the cost is the SAD between the template and the reference block, the cost may be derived based on Equation 2 described above.
  • the decoding apparatus may derive a reference block in the collocated picture indicated by the scaled motion information as a template, and the cost of the reference block among the reference blocks in the search range is increased.
  • the smallest reference block may be derived, and motion information indicating the reference block may be derived as the refined motion information.
  • the search range may be a rectangular area having a height and a width of N with respect to the position in the reference picture indicated by the motion information.
  • N may be 2, 4, or 5 integer pels.
  • the cost of the template and the reference block within the search range may be a sum of absolute differences (SAD) or a mean-reduced SAD between the template and the reference block. When the cost is SAD between the template and the reference block, the cost may be derived based on Equation 3 described above.
  • the decoding apparatus may obtain control syntax information indicating whether a refinement process is applied to a current region including the current block.
  • the refinement process may be performed based on the motion information and the scaled motion information.
  • the current region may be one of a slice, a tile, and a picture.
  • the control syntax information may be signaled through a video parameter set (VPS), a sequence parameter set (SPS), a picture parameter set (PPS), a slice segment header, a coding unit header, or the like. Can be.
  • the decoding apparatus may obtain region syntax information indicating a region to which the refinement process is applied.
  • the refinement process may be performed based on the motion information and the scaled motion information.
  • the region syntax information may be signaled through a video parameter set (VPS), a sequence parameter set (SPS), a picture parameter set (PPS), a slice segment header, or a coding unit header. .
  • the decoding apparatus may obtain the precision syntax information indicating the precision.
  • the refinement process may be performed based on the motion information and the scaled motion information at the location of the unit indicated by the precision syntax information.
  • the precision syntax information may indicate 1/8, 1/4, 1/2, 1, 2, 4, 8, 16, 32, 64, or 128.
  • the precision syntax information may be signaled through a video parameter set (VPS), a sequence parameter set (SPS), a picture parameter set (PPS), a slice segment header, or a coding unit header. .
  • the decoding apparatus may obtain direction syntax information indicating a prediction direction in which the refinement process is performed.
  • the direction syntax information may indicate one of L0 prediction, L1 prediction, and / or pair prediction.
  • a pre-refinement process may be performed when the motion information of the current block is L0 motion information.
  • the refinement process may be performed when the motion information of the current block is L1 motion information.
  • the direction syntax information indicates pair prediction, the refinement process may be performed when the motion information of the current block is pair prediction motion information.
  • the direction syntax information may be signaled through a video parameter set (VPS), a sequence parameter set (SPS), a picture parameter set (PPS), a slice segment header, or a coding unit header. .
  • the decoding apparatus performs prediction on the current block based on the refinement motion information in operation S1430.
  • the decoding apparatus may derive the prediction sample of the current block by performing prediction on the current block based on the refined motion information.
  • a prediction block of the current block may be derived based on the refinement motion information, and a reconstruction block may be derived based on the prediction block.
  • the decoding apparatus may derive a reference block in the reference picture (or the collocated picture) based on the refine motion information.
  • the refined motion information may include a motion vector and a reference picture index.
  • the decoding apparatus may derive the reference picture (or the collocated picture) indicated by the reference picture index as a reference picture of the current block, and a block indicated by the motion vector in the reference picture as a reference block of the current block. Can be derived.
  • the decoding apparatus may generate a prediction sample based on the reference block, and 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 obtain 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
  • FIG. 15 schematically illustrates a decoding apparatus for performing an image decoding method according to the present invention.
  • the method disclosed in FIG. 14 may be performed by the decoding apparatus disclosed in FIG. 15.
  • the prediction unit of the decoding apparatus of FIG. 15 may perform S1400 to S1430 of FIG. 14.
  • a process of acquiring image information including information on prediction of a current block and information on residual through a bitstream may be performed by the entropy decoding unit of the decoding apparatus of FIG. 15.
  • Deriving the residual sample for the current block based on the residual information may be performed by an inverse transform unit of the decoding apparatus of FIG. 15, and based on the prediction sample and the residual sample
  • the process of generating may be performed by the adder of the decoding apparatus of FIG. 15.
  • the DMVR may be performed based on the motion information and the scaled motion information, thereby preventing the pipeline delay from occurring by performing the DMVR based on reconstructed samples of the current picture and other reference pictures. Overall coding efficiency can be improved.
  • a template may be derived from a picture other than the current picture based on the motion information and the scaled motion information, and refinement or reordering may be performed based on the template.
  • DMVR may be performed based on reconstructed samples of a picture to prevent pipeline delay from occurring and to improve overall coding efficiency.
  • the embodiments described herein may be implemented and performed on a processor, microprocessor, controller, or chip.
  • the functional units shown in each drawing may be implemented and performed on a computer, processor, microprocessor, controller, or chip.
  • information for implementation (ex. Information on instructions) or an algorithm may be stored in a digital storage medium.
  • the decoding apparatus and encoding apparatus to which the present invention is applied include a multimedia broadcasting transmitting and receiving device, a mobile communication terminal, a home cinema video device, a digital cinema video device, a surveillance camera, a video chat device, a real time communication device such as video communication, and mobile streaming.
  • the OTT video device may include a game console, a Blu-ray player, an internet access TV, a home theater system, a smartphone, a tablet PC, a digital video recorder (DVR), and the like.
  • the processing method to which the present invention is applied can be produced in the form of a program executed by a computer, and can be stored in a computer-readable recording medium.
  • Multimedia data having a data structure according to the present invention can also be stored in a computer-readable recording medium.
  • the computer readable recording medium includes all kinds of storage devices and distributed storage devices in which computer readable data is stored.
  • the computer-readable recording medium may be, for example, a Blu-ray disc (BD), a universal serial bus (USB), a ROM, a PROM, an EPROM, an EEPROM, a RAM, a CD-ROM, a magnetic tape, a floppy disk, and an optical disc. It may include a data storage device.
  • the computer-readable recording medium also includes media embodied in the form of a carrier wave (eg, transmission over the Internet).
  • the bitstream generated by the encoding method may be stored in a computer-readable recording medium or transmitted through a wired or wireless communication network.
  • an embodiment of the present invention may be implemented as a computer program product by program code, which may be performed on a computer by an embodiment of the present invention.
  • the program code may be stored on a carrier readable by a computer.
  • 16 exemplarily shows a structure diagram of a content streaming system to which the present invention is applied.
  • the content streaming system to which the present invention is applied may largely include an encoding server, a streaming server, a web server, a media storage, a user device, and a multimedia input device.
  • the encoding server compresses content input from multimedia input devices such as a smart phone, a camera, a camcorder, etc. into digital data to generate a bitstream and transmit the bitstream to the streaming server.
  • multimedia input devices such as smart phones, cameras, camcorders, etc. directly generate a bitstream
  • the encoding server may be omitted.
  • the bitstream may be generated by an encoding method or a bitstream generation method to which the present invention is applied, and the streaming server may temporarily store the bitstream in the process of transmitting or receiving the bitstream.
  • the streaming server transmits the multimedia data to the user device based on the user's request through the web server, and the web server serves as a medium for informing the user of what service.
  • the web server delivers it to a streaming server, and the streaming server transmits multimedia data to the user.
  • the content streaming system may include a separate control server.
  • the control server plays a role of controlling a command / response between devices in the content streaming system.
  • the streaming server may receive content from a media store and / or an encoding server. For example, when the content is received from the encoding server, the content may be received in real time. In this case, in order to provide a smooth streaming service, the streaming server may store the bitstream for a predetermined time.
  • Examples of the user device include a mobile phone, a smart phone, a laptop computer, a digital broadcasting terminal, a personal digital assistant (PDA), a portable multimedia player (PMP), a navigation device, a slate PC, Tablet PCs, ultrabooks, wearable devices (e.g., smartwatches, glass glasses, head mounted displays), digital TVs, desktops Computer, digital signage, and the like.
  • Each server in the content streaming system may be operated as a distributed server, in which case data received from each server may be distributed.

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Abstract

La présente invention concerne un procédé de décodage d'une image par un appareil de décodage, comprenant les étapes consistant : à dériver des informations de mouvement d'un bloc courant ; à mettre à l'échelle les informations de mouvement sur la base d'une première distance et d'une seconde distance et déduire les informations de mouvement mises à l'échelle ; à déduire des informations de mouvement affinées en réalisant une procédure d'affinement sur la base des informations de mouvement et des informations de mouvement mises à l'échelle ; et à prédire le bloc courant sur la base des informations de mouvement affinées, la première distance correspondant à une différence entre un comptage d'ordre d'image (POC) d'une image de référence comprenant les informations de mouvement et un POC d'une image courante, et la seconde distance correspondant à une différence entre un POC d'une image colocalisée comprenant les informations de mouvement mises à l'échelle et le POC de l'image courante.
PCT/KR2019/006037 2018-05-21 2019-05-21 Procédé et appareil de décodage d'image à l'aide de dmvr dans un système de codage d'images WO2019225932A1 (fr)

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