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WO2011149292A2 - Procédé et appareil de traitement de signaux vidéo - Google Patents

Procédé et appareil de traitement de signaux vidéo Download PDF

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Publication number
WO2011149292A2
WO2011149292A2 PCT/KR2011/003877 KR2011003877W WO2011149292A2 WO 2011149292 A2 WO2011149292 A2 WO 2011149292A2 KR 2011003877 W KR2011003877 W KR 2011003877W WO 2011149292 A2 WO2011149292 A2 WO 2011149292A2
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Prior art keywords
component
motion vector
current partition
partition
value
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Korean (ko)
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WO2011149292A3 (fr
Inventor
박승욱
임재현
김정선
박준영
최영희
성재원
전병문
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LG Electronics Inc
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LG Electronics Inc
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
    • H04N19/134—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the element, parameter or criterion affecting or controlling the adaptive coding
    • H04N19/136—Incoming video signal characteristics or properties
    • H04N19/137—Motion inside a coding unit, e.g. average field, frame or block difference
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
    • H04N19/102—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the element, parameter or selection affected or controlled by the adaptive coding
    • H04N19/103—Selection of coding mode or of prediction mode
    • H04N19/105—Selection of the reference unit for prediction within a chosen coding or prediction mode, e.g. adaptive choice of position and number of pixels used for prediction
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
    • H04N19/169—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding
    • H04N19/17—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding the unit being an image region, e.g. an object
    • H04N19/172—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding the unit being an image region, e.g. an object the region being a picture, frame or field

Definitions

  • the present invention relates to a method and apparatus for processing a video signal, and more particularly, to a video signal processing method and apparatus for encoding or decoding a video signal.
  • Compression coding refers to a series of signal processing techniques for transmitting digitized information through a communication line or for storing in a form suitable for a storage medium.
  • the object of compression encoding includes objects such as voice, video, text, and the like.
  • a technique of performing compression encoding on an image is called video image compression.
  • Compression coding on a video signal is performed by removing redundant information in consideration of spatial correlation, temporal correlation, and stochastic correlation.
  • inter-screen prediction obtains a motion vector prediction value of a current partition using motion information of neighboring partitions, obtains a prediction value of the current partition through a motion vector obtained by adding the motion vector difference value, and then obtains a current partition. You can restore the pixel value of.
  • the image having a lot of horizontal motion change, the image having a lot of vertical motion change, rotated or enlarged / reduced There may be various kinds of images such as images.
  • the present invention has been devised to solve the above requirements, and in the motion vector prediction of the current partition, first processing any one component of the motion vector x component and y component as a first component, and first processing the first It is an object of the present invention to provide a method for treating the remaining second component by using the component.
  • an object of the present invention is to provide a method for obtaining a motion vector first component prediction value of a current partition using a motion vector first component of neighboring partitions.
  • Another object of the present invention is to provide a method for determining a first component to be processed first among the motion vector x component and y component of the current partition in order to adaptively increase the accuracy of image prediction.
  • the present invention is to improve the accuracy of motion vector prediction by obtaining the motion vector prediction value of the current partition in consideration of the partition shape of the current partition and the neighbor partition in the motion vector prediction of the partition on which the geometric partition is performed. Have.
  • the present invention provides an affine transformation using motion vectors of neighboring partitions to predict the motion vector of the current partition, thereby improving the accuracy of motion vector prediction for a particular motion situation.
  • the video signal processing method by varying the method of adaptively obtaining the motion vector prediction value according to various image characteristics, it is possible to increase the accuracy of motion vector prediction and to reduce the amount of information transmitted for the reconstruction of the image signal. Will be.
  • the motion vector prediction method can be determined efficiently and adaptively depending on whether the current video is a video with a lot of motion change in the horizontal direction, a video with a lot of motion change in the vertical direction, or a video that is rotated or enlarged / reduced. Can be.
  • motion vector prediction can be performed using the motion vector scaled value, thereby extending the candidate group for motion vector prediction. More accurate predictions are possible.
  • the decoder directly derives the flag without transmitting the flag value, thereby increasing the accuracy of motion vector prediction and minimizing the amount of transmission information.
  • FIG. 1 is a schematic block diagram of a video signal encoder apparatus according to an embodiment of the present invention.
  • FIG. 2 is a schematic block diagram of a video signal decoder device according to an embodiment of the present invention.
  • FIG. 3 is a diagram illustrating an example of splitting a coding unit according to an embodiment of the present invention.
  • FIG. 4 is a diagram illustrating an embodiment of a method for hierarchically representing the partition structure of FIG. 3.
  • FIG. 5 is a diagram illustrating a partitioning form into various sub-prediction units within a prediction unit according to an embodiment of the present invention.
  • FIG. 6 is a diagram illustrating a form obtained by dividing a prediction unit geometrically.
  • FIG. 8 is a diagram illustrating a temporal neighboring partition of the current partition.
  • FIG. 9 is a diagram illustrating a method of scaling a motion vector according to a temporal distance between reference pictures.
  • FIG. 10 is a flowchart illustrating a process of obtaining a motion vector first component and a motion vector second component of a current partition according to an embodiment of the present invention.
  • FIG. 11 is a flowchart illustrating a specific embodiment of obtaining a motion vector first component prediction value of a current partition according to an embodiment of the present invention.
  • FIG. 12 is a flowchart illustrating a specific embodiment of obtaining a motion vector second component prediction value of a current partition according to an embodiment of the present invention.
  • FIG. 13 and 14 show examples of geometrically divided partitions and their neighboring partitions.
  • FIG. 16 illustrates center coordinates of current and neighboring partitions for obtaining an affine motion vector and center coordinates moved through the motion vector.
  • a method of processing a video signal including: obtaining a motion vector first component prediction value of a current partition using motion vector first components of neighboring partitions; Obtaining a motion vector first component of the current partition using the motion vector first component prediction value of the current partition; Obtaining a motion vector second component prediction value of the current partition based on the motion vector first component of the current partition; Obtaining a motion vector second component of the current partition using the motion vector second component prediction value of the current partition; Obtaining a prediction value of a current partition using a motion vector first component and a second component of the current partition; And reconstructing pixel values of the current partition by using the predicted value of the current partition, wherein the first component is a component to be first decoded among the x component and the y component of the motion vector. It is characterized in that the remaining one component after the decoding is performed after the first component.
  • the obtaining of the motion vector first component prediction value of the current partition may be obtained by using motion vector first components of neighboring partitions having the same reference picture as the current partition, but there is no neighboring partition having the same reference picture.
  • the median value of the motion vector first components of the neighbor partitions may be obtained as the motion vector first component prediction value of the current partition.
  • the motion vector first component prediction value of the current partition may be obtained through the median of the scaled motion vector first component of the neighbor partitions.
  • the obtaining of the motion vector second component prediction value of the current partition may include: obtaining a neighbor partition having a motion vector first component whose minimum value of the difference with the motion vector first component of the current partition is minimum; A motion vector second component prediction value of the current partition may be obtained using the motion vector second component of the neighbor partition.
  • the method may further include determining a first component of the motion vector x component and y component of the current partition to be decoded first. can do.
  • the determining of the first component may be obtained through the transmitted flag value.
  • an average value of absolute values of the motion vector x component and y component of the previous frame may be obtained, and a component having a smaller size may be determined as the first component.
  • an average value of absolute values of the motion vector x and y components of neighboring partitions of the current partition may be obtained, and a component having a smaller size may be determined as the first component.
  • the corresponding component when there is a component having one valid value among the motion vector x component and y component of neighboring partitions of the current partition, the corresponding component may be determined as the first component.
  • Coding can be interpreted as encoding or decoding in some cases, and information is a term that includes values, parameters, coefficients, elements, and the like. May be interpreted otherwise, the present invention is not limited thereto.
  • 'Unit' is used to mean a basic unit of image processing or a specific position of an image, and in some cases, may be used interchangeably with terms such as 'block', 'partition' or 'region'.
  • a unit may be used as a concept including a coding unit, a prediction unit, and a transform unit.
  • the encoding apparatus 100 of the present invention is largely composed of a transformer 110, a quantizer 115, an inverse quantizer 120, an inverse transformer 125, a filter 130, and a predictor ( 150 and the entropy coding unit 160.
  • the converter 110 obtains a transform coefficient value by converting a pixel value of the input video signal.
  • Discrete Cosine Transform DCT
  • Wavelet Transform DCT
  • the discrete cosine transform divides the input image signal into blocks having a predetermined size and performs the conversion.
  • the coding efficiency may vary depending on the distribution and the characteristics of the values in the transform domain.
  • the quantization unit 115 quantizes the transform coefficient value output from the transform unit 110.
  • the inverse quantization unit 120 inverse quantizes the transform coefficient value, and the inverse transform unit 125 restores the original pixel value by using the inverse quantized transform coefficient value.
  • the filtering unit 130 performs a filtering operation for improving the quality of the reconstructed image.
  • a deblocking filter and an adaptive loop filter may be included.
  • the filtered image is stored in the storage unit 156 for output or use as a reference image.
  • a method of predicting an image by using an already coded region and adding a residual value between the original image and the predicted image to a reconstructed image is used instead of coding the image signal as it is.
  • the intra predictor 152 performs intra prediction within the current image
  • the inter predictor 154 predicts the current image using the reference image stored in the storage 156.
  • the intra prediction unit 152 performs intra prediction from the reconstructed regions in the current image, and transmits the intra encoding information to the entropy coding unit 160.
  • the inter predictor 154 may further include a motion compensator 162 and a motion estimator 164.
  • the motion estimator 164 obtains a motion vector value of the current region by referring to the restored specific region.
  • the motion estimator 164 transmits the position information (reference frame, motion vector, etc.) of the reference region to the entropy coding unit 160 so that the motion estimation unit 164 may be included in the bitstream.
  • the motion compensator 162 performs inter-screen motion compensation by using the motion vector value transmitted from the motion estimator 164.
  • the entropy coding unit 160 entropy codes the quantized transform coefficients, inter picture encoding information, intra picture encoding information, and reference region information input from the inter prediction unit 154 to generate a video signal bitstream.
  • the entropy coding unit 160 may use a variable length coding (VLC) method, arithmetic coding, or the like.
  • VLC variable length coding
  • the variable length coding (VLC) scheme converts input symbols into consecutive codewords, which may have a variable length. For example, frequently occurring symbols are represented by short codewords and infrequently occurring symbols by long codewords.
  • a context-based adaptive variable length coding (CAVLC) method may be used as a variable length coding method.
  • Arithmetic coding converts consecutive data symbols into a single prime number, which can obtain the optimal fractional bits needed to represent each symbol.
  • Context-based Adaptive Binary Arithmetic Code (CABAC) may be used as arithmetic coding.
  • the decoding apparatus 200 of the present invention largely includes an entropy decoding unit 210, an inverse quantization unit 220, an inverse transform unit 225, a filtering unit 230, and a prediction unit 250.
  • the entropy decoding unit 210 entropy decodes the video signal bitstream and extracts transform coefficients, motion vectors, and the like for each region.
  • the inverse quantization unit 220 inverse quantizes the entropy decoded transform coefficient, and the inverse transform unit 225 restores the original pixel value by using the inverse quantized transform coefficient.
  • the filtering unit 230 performs filtering on the image to improve the image quality. This may include a deblocking filter to reduce block distortion and / or an adaptive loop filter to remove distortion of the entire image.
  • the filtered image is output or stored in the frame storage unit 256 for use as a reference image for the next frame.
  • the predictor 250 of the present invention includes an intra predictor 252 and an inter predictor 254, and includes a coding type decoded by the entropy decoder 210 described above, a transform coefficient for each region, The prediction image is reconstructed by using information such as a motion vector.
  • the intra prediction unit 252 performs the intra prediction from the decoded samples in the current image.
  • the inter predictor 254 estimates a motion vector by using the reference image stored in the frame storage 256 and generates a predicted image.
  • the inter predictor 254 may again include a motion compensator 262 and a motion estimator 264.
  • the motion estimator 264 obtains a motion vector indicating a relationship between a current block and a reference block of a reference frame used for coding and transfers the motion vector to the motion compensator 262.
  • the predicted value output from the intra predictor 252 or the inter predictor 254 and the pixel value output from the inverse transform unit 225 are added to generate a reconstructed video frame.
  • a coding unit is a process such as intra / inter prediction, transform, quantization and / or entropy coding in the processing of the video signal described above. Means the basic unit for processing the image. The size of the coding unit used to code one image may not be constant. The coding unit may have a rectangular shape, and one coding unit may be further divided into several coding units.
  • FIG. 3 illustrates an example of splitting a coding unit according to an embodiment of the present invention.
  • one coding unit having a size of 2N ⁇ 2N may be divided into four coding units having a size of N ⁇ N.
  • the splitting of such coding units can be done recursively, and not all coding units need to be split in the same form.
  • FIG. 4 illustrates an embodiment of a method for hierarchically representing a division structure of a coding unit illustrated in FIG. 3 using 0 and 1.
  • FIG. Information indicating whether a coding unit is divided may be allocated to a value of '1' when the corresponding unit is divided and '0' when it is not divided.
  • a flag value indicating whether to split is 1, a coding unit corresponding to a corresponding node is divided into 4 coding units, and when 0, a processing process for the coding unit is performed without being divided further. Can be.
  • the coding unit may not necessarily be divided into four forward regions.
  • a code for a predetermined partitioning scheme may be mapped to the partitioning information. For example, if the information value is 1, the coding unit is divided into two horizontal rectangular sub-coding units, if 2, the coding unit is divided into two vertical rectangular sub-coding units, and 3 is four square sub-coding units. It can also be set to divide by.
  • Such a method shows some embodiments of a division method, and does not limit the present invention.
  • the structure of the coding unit described above may be represented using a recursive tree structure. That is, a coding unit split into another coding unit with one picture or maximum size coding unit as a root has as many child nodes as the number of split coding units. Thus, coding units that are no longer split become leaf nodes. Assuming that only square division is possible for one coding unit, one coding unit may be divided into up to four other coding units, so the tree representing the coding unit may be in the form of a quad tree.
  • an optimal coding unit size may be selected according to the characteristics (eg, resolution) of the video image or in consideration of coding efficiency, and information about the coding unit may be included in the bitstream. For example, the size of the largest coding unit and the maximum depth of the tree can be defined. In the case of square division, since the height and width of the coding unit are half the height and width of the coding unit of the parent node, the minimum coding unit size can be obtained using the above information. Alternatively, the minimum coding unit size and the maximum depth of the tree may be defined in advance, and the maximum coding unit size may be derived and used if necessary. Since the size of the unit changes in a multiple of 2 in square division, the size of the actual coding unit is represented by a logarithm of the base of 2, thereby improving transmission efficiency.
  • the decoder may obtain information indicating whether the current coding unit is split. This information can be obtained only if the information is obtained (transmitted) under certain conditions, thereby increasing efficiency.
  • the condition that the current coding unit can be divided is information indicating whether the current coding unit size is divided in this case because the current coding unit size is smaller than the picture size and the current unit size is larger than the preset minimum coding unit size. Can be obtained.
  • the size of the coding unit to be split is half of the current coding unit, and is split into four square coding units based on the current processing position. The above process can be repeated for each divided coding units.
  • Picture prediction (motion compensation) for coding is directed to coding units (i.e. leaf nodes of the coding unit tree) that are no longer divided.
  • the basic unit for performing such prediction is called a prediction unit, a prediction block, or a partition.
  • the prediction unit may be divided into various forms, and may be divided into symmetrical forms such as squares, rectangles, sub-prediction units of asymmetrical forms, or geometrical forms.
  • one prediction unit may not be split (2Nx2N) or may be divided into sub-prediction units of size NxN, 2NxN, Nx2N, etc. as shown in FIG.
  • the possible division forms of the prediction unit may be defined differently in the intra coding unit and the inter coding unit.
  • the bitstream may include information about whether the prediction unit is divided or in what form. Or this information may be derived from other information.
  • Partitioning may not necessarily be symmetrical. That is, the prediction unit may be divided into asymmetrically divided into rectangles of different sizes, and as shown in FIG. 6, geometric partitions may be generated in various shapes other than a rectangular shape. In this case, the prediction unit is divided into two partitions 610 and 620 through an arbitrary dividing line 600.
  • the division information may be expressed as a distance ⁇ from the center of the dividing line, an angle ⁇ between the repair line from the center O to the dividing line and the reference axis (for example, the x-axis).
  • Such various types of prediction unit partitioning have an advantage of enabling more accurate prediction of various types of objects included in an image.
  • partition may be used as a replacement term for the prediction unit or sub-prediction unit, which is a basic unit for performing prediction.
  • the present invention is not limited thereto.
  • the decoded portion of the current picture or other pictures containing the current partition may be used to reconstruct the current partition on which decoding is performed.
  • Intra picture or I picture (slice) using only the current picture for reconstruction i.e., performing only intra-picture prediction, predicting a picture (slice) using at most one motion vector and reference index to predict each partition
  • a picture using a predictive picture or a P picture (slice), up to two motion vectors, and a reference index (slice) is called a bi-predictive picture or a B picture (slice).
  • the intra prediction unit performs intra prediction for predicting pixel values of the target partition from the reconstructed regions in the current picture.
  • the pixel value of the current partition can be predicted from the encoded pixels of the partitions located at the top, left, top left and / or top right with respect to the current partition.
  • the intra mode may be divided into vertical, horizontal, DC, and angular modes according to the direction and prediction method of the reference region where the reference pixels used for pixel value prediction are located.
  • the vertical mode is used as a prediction value of the current partition with reference to the value of the vertically adjacent area of the target partition
  • the horizontal mode is used as a prediction value with reference to the value of the horizontally adjacent area.
  • the DC mode the average value of the reference regions is used as a prediction value.
  • the reference region is located in an arbitrary direction and may indicate the corresponding direction by an angle between the current pixel and the reference pixel.
  • a predetermined angle and prediction mode number may be used, and the number of angles used may vary depending on the size of the target partition.
  • the prediction mode may be transmitted as a value indicating the mode itself, but in order to increase transmission efficiency, a method of predicting a prediction mode value of the current partition may be used.
  • the decoder may obtain the prediction mode of the current partition using information using whether the prediction value for the prediction mode is used as it is or how much the difference with the actual value is.
  • the inter prediction unit performs inter prediction for predicting a pixel value of a target partition by using information of other reconstructed pictures other than the current picture.
  • a picture used for prediction is referred to as a reference picture.
  • Which reference region is used to predict the current partition in the inter prediction process may be indicated by using an index indicating a reference picture including the reference region, motion vector information, and the like.
  • the inter prediction may include forward direction prediction, backward direction prediction, and bi-prediction.
  • Forward prediction is prediction using one reference picture displayed (or output) before the current picture in time
  • backward prediction means prediction using one reference picture displayed (or output) after the current picture in time.
  • one motion information eg, a motion vector and a reference picture index
  • up to two reference regions may be used, and these two reference regions may exist in the same reference picture or may exist in different pictures, respectively. That is, in the pair prediction method, up to two motion information (eg, a motion vector and a reference picture index) may be used.
  • the two motion vectors may have the same reference picture index or may have different reference picture indexes. .
  • the reference pictures may be displayed (or output) before or after the current picture in time.
  • the motion information of the current partition may include motion vector information and a reference picture index.
  • the motion vector information may include a motion vector, a motion vector prediction (mvp), a motion vector difference (mvd), or mean index information for specifying the motion vector prediction value.
  • the differential motion vector means a difference value between the motion vector and the motion vector prediction value.
  • the reference partition of the current partition can be obtained using the motion vector and the reference picture index.
  • the reference partition exists in a reference picture having the reference picture index.
  • a pixel value or an interpolated value of a partition specified by the motion vector may be used as a predictor of the current partition. That is, using motion information, motion compensation is performed to predict an image of a current partition from a previously decoded picture.
  • a reference picture list may be configured of pictures used for inter prediction for the current picture.
  • two reference picture lists are required, and in the following, each of them is referred to as reference picture list 0 (or L0) and reference picture list 1 (or L1).
  • a method of obtaining a motion vector prediction value mvp by using motion information of previously coded partitions and transmitting only a difference value mvd thereof The decoder obtains a motion vector prediction value of the current partition using motion information of other decoded partitions, and obtains a motion vector value for the current partition using the transmitted difference value.
  • a motion vector competition method may be used in which various motion vector candidate values are obtained by using motion information of already coded partitions, and one of them is obtained as the motion vector prediction value.
  • the motion vector prediction value of the current partition may be obtained from the motion vectors of neighboring partitions of the current partition.
  • Such neighbor partitions may include spatial neighbor partitions and temporal neighbor partitions.
  • a spatial neighbor partition refers to partitions adjacent to the current partition within the same picture as the current partition (see FIG. 7), and a temporal neighbor partition is a partition existing at a position co-located with the current partition in a picture different from the current partition. (See Fig. 8).
  • the spatial neighbor partitions include partitions A 0 , A 1 ,..., A nA neighboring the left side of the current partition, and neighboring partitions B 0 at the top of the current partition. , B 1 ,..., B nB ) and / or partitions C, D, E adjacent to the diagonal of the current partition may be included. In this case, the size of each neighboring partition may be different.
  • the motion vector prediction value of the current partition is obtained from the motion vectors of the spatial neighboring partition and / or the temporal neighboring partition of the current partition, and the motion vector value for the current partition can be obtained by adding this to the transmitted difference value.
  • the current picture (or slice) is a P picture (slice)
  • a motion vector prediction value and a motion vector for a prediction direction (reference picture list) of either L0 or L1 may be obtained, and the current picture (or slice) may be obtained.
  • the motion vector prediction value and the motion vector for the prediction directions of both L0 and L1 can be obtained.
  • Motion vector scaling refers to a technique of scaling up or scaling down a motion vector according to a temporal distance between reference pictures and a current picture.
  • 9 illustrates a method of performing motion vector scaling using a temporal distance between pictures.
  • mvL0N_scaled mvL0 * (tb / td)
  • td denotes a temporal distance between the current picture and ref1
  • tb denotes a temporal distance between the current picture and ref0.
  • the temporal distance between each picture may be obtained through a difference of a picture order count (POC) value between each picture.
  • POC picture order count
  • one component (first component) of the motion vector x component and y component of the current partition is first obtained, and the remaining other components (first component) are obtained using the first component.
  • first component the remaining other components
  • 10 is a diagram illustrating such a motion vector prediction value and a motion vector acquisition process according to an embodiment of the present invention.
  • a motion vector first component prediction value of the current partition may be obtained (S1020).
  • the step of determining the first component of the motion vector x component and y component of the current partition S1010
  • the motion vector first component prediction value of the current partition may be obtained using the motion vector first components of neighboring partitions of the current partition.
  • the motion vector first component of the current partition may be obtained by adding the first motion vector difference value (first component) to the received motion vector (S1030).
  • a motion vector second component prediction value of the current partition can be obtained (S1040).
  • the present invention finds a neighbor partition having a motion vector first component value most similar to the motion vector first component of the current partition among the neighbor partitions, and uses the motion vector second component value of the partition to determine the motion of the current partition.
  • a vector second component prediction value may be obtained.
  • the motion vector second component prediction value of the current partition may be obtained by adding the motion vector difference value (second component) to the transmitted motion vector (S1050).
  • a prediction value of the current partition may be obtained using the motion vector first component and the second component of the current partition obtained through the above process (S1060), and the pixel value of the current partition may be restored using this.
  • FIGS. 11 and 12 illustrate a process of obtaining a motion vector first component prediction value and a second component prediction value of a current partition in detail according to an embodiment of the present invention.
  • a motion vector y component is a first component and an x component is a second component will be described with reference to FIGS. 11 and 12.
  • the first component may be substituted with the motion vector x component and the second component with the motion vector y component.
  • steps S1110 to S1160 of FIG. 11 specify an example of a process of obtaining a motion vector y component prediction value of the current partition (S1020).
  • a motion vector y component (mvX [1]) of neighboring partitions having the same reference picture as the current partition may be added to the y component list listMvCompY (S1110).
  • the number of candidate motion vector y component predicted values numCompY of the current partition is obtained through the number of elements included in the y component listMvCompY (S1112).
  • the motion vector y component predicted value mvPred [1] of the current partition can be obtained according to the value of the y component predicted value candidate number numCompY in the following manner.
  • the median value of the motion vector y components mvX [1] of the neighbor partitions may be set as the motion vector y component prediction value mvPred [1] of the current partition.
  • the median value of the scaled motion vector y component of the neighbor partitions may be set to mvPred [1]. That is, the motion vector y components of neighboring partitions are scaled with respect to the reference picture of the current partition, and the median value of the scaled motion vector y components is assigned to mvPred [1].
  • the mvPred [1] may be set to 0.
  • the motion vector y component of the neighbor partition may be set as the motion vector y component prediction value mvPred [1] of the current partition (S1132). That is, listMvCompY [0], the only element added to the y component list, may be assigned as the value of mvPred [1].
  • the average of the motion vector y components (listMvCompY [0], listMvCompY [1]) of the two neighboring partitions is the motion vector y component of the current partition.
  • the prediction value mvPred [1] can be set (S1142).
  • the motion vector y component of the partition having the larger size among two neighboring partitions included in the y component list may be set to mvPred [1]. If the sizes of the two neighboring partitions are the same, the average value of the motion vector y component may be set to mvPred [1] as in step S1142.
  • the median value of the motion vector y component of the corresponding neighbor partitions may be set as the motion vector y component prediction value mvPred [1] of the current partition.
  • the elements included in the y component list listMvCompY are sorted in ascending (or descending) order (S1150), and the motion vectors y of neighboring partitions are obtained by obtaining the elements of the center index of the sorted y component list listMvCompY.
  • the median value of the components can be obtained (S1160).
  • the motion vector y component prediction value mvPred [1] of the current partition obtained through the processes of S1110 to S1160 is summed with the transmitted motion vector difference value y component mvDiff [1] to add the motion vector y component of the current partition ( currMv [1]) can be obtained (S1030).
  • a process of obtaining a motion vector x component prediction value mvPred [0] of the current partition based on the motion vector y component (currMv [1]) of the current partition (S1040).
  • An example is given.
  • the motion vector x component (mvX [0]) of neighboring partitions having the same reference picture as the current partition is added to the motion vector list listMv. Can be added (S1210).
  • the number numMv of elements included in the motion vector list listMv is obtained (S1212).
  • the numMv is 0 (S1220)
  • the median value of the motion vector x components (mvX [0]) of the neighbor partitions is determined.
  • the predicted value mvPred [0] can be set (S1222).
  • the median value of the scaled motion vector x component of neighboring partitions may be set to mvPred [0] for more accurate motion vector prediction.
  • the motion vector x components of neighboring partitions are scaled with respect to the reference picture of the current partition, and the median value of the scaled motion vector x components is assigned to mvPred [0].
  • the mvPred [0] may be set to 0.
  • a motion vector x component prediction value mvPred [0] of the current partition may be obtained. That is, the neighbor partition having the motion vector y component value most similar to the motion vector y component (currMv [1]) of the current partition is searched, and the motion vector x component of the neighbor partition is predicted by the motion vector x component prediction value (mvPred) of the current partition. [0]).
  • the motion vector x component prediction value of the current partition may be obtained by the following process. can do. First, among the motion vector y components of the neighbor partition added to the motion vector list listMv, the element listMv [i whose absolute value of the difference from the motion vector y component currMv [1] of the current partition is minimum ] [1]) is set to compY (S1230).
  • the motion vector x component listMv [i] [0] of neighboring partitions having the same value as the compY is set. It adds to x component list listMvCompX (S1232).
  • a motion vector x component prediction value candidate number numCompX of the current partition may be obtained (S1234), and according to the value of the x component prediction value candidate number numCompX.
  • the motion vector x component prediction value (mvPred [0]) of the current partition can be obtained by the following method.
  • the motion vector x component of the corresponding two neighbor partitions (listMvCompX [0], An average of listMvCompX [1]) may be set as the motion vector x component predicted value mvPred [0] of the current partition (S1252).
  • numCompX 2
  • the motion vector x component of a partition having a larger size among two neighboring partitions included in the x component list may be set to mvPred [0]. If the sizes of the two neighboring partitions are the same, the average value of the motion vector x component may be set to mvPred [0] in step S1252.
  • the median value of the motion vector x component of the corresponding partitions is set to the motion vector x component of the current partition.
  • the prediction value may be set to mvPred [0].
  • the elements included in the x component list listMvCompX are sorted in ascending (or descending order) (S1260), and the motion elements of the neighboring partitions are obtained by obtaining the center elements of the sorted list of the x component listMvCompX.
  • the median value may be obtained (S1270).
  • the motion vector x component prediction value mvPred [0] of the current partition obtained through the processes of S1210 to S1270 is summed with the transmitted motion vector difference value x component (mvDiff [0]) to obtain the motion vector x component of the current partition ( currMv [0]) can be obtained (S1050).
  • the order of the coded motion vector x component and y component may be adaptively determined.
  • the x and y components of the motion vector may be different from each other.
  • the method may further include a step (S1010) of determining a first component from which the first decoding of the motion vector x component and y component of the current partition is performed.
  • the determining step S1010 may use a signaling method for acquiring the first component through a transmitted flag value, or may use a method of deriving the first component from a decoder side without signaling.
  • the signaling comprises i) at the Sequence Parameter Set (SPS) step, ii) at the Picture Parameter Set (PPS) step, iii) at the slice header, iv) at the largest Coding Tree Block. , Largest CTB) step, v) prediction unit (PU) step, or vi) partition (Motion partition) step.
  • SPS Sequence Parameter Set
  • PPS Picture Parameter Set
  • PU prediction unit
  • partition partition Motion partition
  • the derivation method may be performed in units of frames (or pictures) or in units of partitions.
  • the first component when deriving the first component on a frame basis, statistical information of motion vectors of a previously coded frame may be used. For example, if the previously decoded image has more motion vector changes in the horizontal direction, the current frame first decodes the motion vector y component, and vice versa, the current frame decodes the motion vector x component first. can do.
  • the first component may be derived in frame units through the following method.
  • the first component when the first component is derived in a partition unit, statistical information of motion vectors of neighboring partitions may be used. For example, if the motion vectors of neighboring partitions have more changes in the horizontal direction, the current partition may first decode the motion vector y component, and vice versa, the current partition may decode the motion vector x component first. have.
  • the first component may be derived in a partition unit through the following method.
  • the x component is determined as the first component, otherwise the y component is determined as the first component (or vice versa).
  • the signaling method and the derivation method may be used in combination to determine the first component of the current partition. That is, a flag for determining a first component for each prediction direction L0 / L1 may be transmitted in partition units, but the first component may be directly derived without transmitting the flag for a partition having a specific condition. . According to an embodiment of the present invention, the flag may not be transmitted when any one of the following conditions is met.
  • the neighbor partition may include both a spatial neighbor partition and a temporal neighbor partition.
  • the motion vector of a valid neighbor partition to be used for motion vector prediction of the current partition may include only the motion vector of a neighbor partition having the same reference picture as the current partition, or the motion vector of a neighbor partition having another reference picture is included together.
  • the scaled motion vector may be included in consideration of the temporal distance between the reference pictures as described above.
  • a scaled motion vector may be used in consideration of a temporal distance between reference pictures.
  • the efficiency of motion vector prediction is reduced because the motion vector prediction value of the component to be processed later is fixed regardless of the value of the component to be processed first. Therefore, in this case, the component having one valid value can be coded first without having to transmit a separate flag. For example, if the motion vector predictor candidate list of the current partition is ⁇ (5, -1), (5, 3), (5, 7) ⁇ , the x component of the motion vector predictor candidate is ⁇ 5 ⁇ , and the motion The y component of the vector predictor candidate is ⁇ -1, 3, 7 ⁇ . At this time, by processing the x component having one valid value first, it can be used to increase the accuracy of the motion vector y component prediction of the current partition.
  • a method of processing the y component of the motion vector predicted value first, but processing the x component first for a partition in a specific condition may be used. That is, when there is only one value of the motion vector x component of the valid neighbor partition used for motion vector prediction of the current partition, the x component may be coded first.
  • motion vector prediction may be performed on geometrically divided partitions as shown in FIG. 6.
  • a motion vector prediction value of the current partition may be obtained by using motion vectors of neighboring partitions adjacent to each partition.
  • the topmost partition A of the left neighboring partitions of the current coding unit For example, as shown in FIG. 13, the topmost partition A of the left neighboring partitions of the current coding unit, the leftmost partition B of the top neighboring partitions of the current coding unit, and the neighbors of the upper right corner of the current coding unit.
  • the partition C When the partition C is adjacent to the current partition G1, the median of the motion vectors of the partitions A, B, and C may be used as the motion vector prediction value of the current partition G1.
  • neighbor partitions A, B, E (the rightmost partition among the top neighboring partitions of the current coding unit), F (the bottommost partition among the left neighboring partitions of the current coding unit), and C
  • a partition adjacent to the current partition G1 may be searched to use the motion vector of the neighboring partition as the motion vector prediction value of the current partition G1. If there is no neighbor partition adjacent to the current partition, the motion vector prediction value of the current partition may be set to (0, 0).
  • the motion vector of the neighbor partition is used as the motion vector prediction value of the current partition. Can be used.
  • the motion vector of another partition in the same coding unit may be used as the motion vector prediction value of the current partition. That is, in FIG. 12, the partition G2 in which the geometric division is performed does not have adjacent neighbor partitions, but may obtain a motion vector of G1, which is another adjacent partition in the same coding unit, and use it as a motion vector prediction value.
  • the motion vector prediction of the current partition is performed by using the median of the motion vectors of the neighboring partitions or the motion vector of the selected neighboring partition. As the motion vector difference is reduced, the amount of data to be transmitted is reduced. However, in the actual image sequence, various motions such as rotation and zooming are present, and in such an image, the possibility that the current partition has the same motion vector as the neighboring partition becomes small.
  • FIG. 15 illustrates a situation in which peripheral partition areas including partition X are reduced around partition X.
  • the motion vector MV of the current partition is one of the motion vectors MVa, MVb, and MVc of neighboring partitions. It may not have the same value as anything.
  • the motion vector MVb of partition B which is the median motion vector of neighboring partitions
  • MVp the motion vector prediction value
  • MVd which is a difference from the actual motion vector MV, should be transmitted. Therefore, a method for reducing the motion vector difference value MVd is needed.
  • affine transformation may be performed using the motion vectors of neighboring partitions on the assumption that the current partition X has a motion vector similar to neighboring partitions A, B, and C.
  • the affine transformation vector thus obtained can more accurately predict the operation of the current partition X, etc., thereby reducing the motion vector difference value.
  • a method of obtaining an affine transform vector from motion vectors of neighboring partitions will be described with reference to FIG. 16.
  • the origin (0, 0) for coordinate calculation is the center of the current partition X, and the coordinates of the centers of neighboring partitions A, B, and C are (xa, ya), (xb, yb), and (xc, yc), respectively. do.
  • the point where the center of each neighboring partition is moved by each motion vector MVa, MVb, MVc is called (xa ', ya'), (xb ', yb'), (xc ', yc'). .
  • the affine transformation vector A obtained from the motions of the three neighboring partitions A, B, and C is as follows.
  • the motion vector prediction value MVp of the current partition can be obtained using the affine transform vector A as follows.
  • a parametric transform vector is calculated from the decoded neighbor partitions and the motion vector of the current partition, and motion compensation of the current partition is performed using the same.
  • the affine transformation model of the aforementioned method may be used as the model of the parametric transformation vector.
  • the origin (0, 0) for the coordinate calculation is the center of the current partition X
  • the coordinates of the centers of the neighbor partitions A, B, C and the current partition X are (xa, ya), (xb, yb), (xc, yc) and (xd, yd).
  • the centers of the neighboring partitions A, B, C and the current partition X are moved by the respective motion vectors MVa, MVb, MVc, and MV (xa ', ya'), (xb ', yb'). ), (xc ', yc') and (xd ', yd').
  • the affine transformation vector A 'obtained from the motions of the three neighboring partitions A, B, and C and the current partition X is as follows.
  • Motion compensation for the current partition may be performed using the affine transform vector A '. That is, when the coordinate of any point in the current partition X is (x, y), the coordinate (x ', y') in the reference picture may be calculated as follows.
  • the motion vector prediction value MVp of the current partition obtained by using the affine transform vector A may be added as one of candidates used for existing motion vector competition.
  • the decoding / encoding method to which the present invention is applied may be stored in a computer-readable recording medium that is produced as a program for execution on a computer, and the computer-readable recording medium may also have multimedia data having a data structure according to the present invention. Can be stored in.
  • the computer readable recording medium includes all kinds of storage devices in which data that can be read by a computer system is stored. Examples of computer-readable recording media include ROM, RAM, CD-ROM, magnetic tape, floppy disk, optical data storage, and the like, and may also be implemented in the form of a carrier wave (for example, transmission over the Internet). Include.
  • the bitstream generated by the encoding method may be stored in a computer-readable recording medium or transmitted using a wired / wireless communication network.
  • Embodiments according to the present invention may be implemented by various means, for example, hardware, firmware, software, or a combination thereof.
  • embodiments described herein include application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), and the like. It may be implemented using at least one of processors, controllers, micro-controllers, microprocessors, and electrical partitions for performing other functions. The described embodiments may be implemented by the controller itself.
  • embodiments such as the procedures and functions described herein may be implemented as separate software modules.
  • Each of the software modules may perform one or more functions and operations described herein.
  • Software code may be implemented in software applications written in a suitable programming language.
  • the software code may be stored in a memory and executed by a controller.
  • the present invention can be applied to encoding or decoding a video signal.

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Abstract

La présente invention porte sur un procédé et un appareil de codage ou de décodage de signaux vidéo. Afin d'augmenter la précision de prédiction d'image, la présente invention peut déterminer de manière efficace et adaptative un procédé de prédiction de vecteur de mouvement selon si une image présente est une image ayant davantage de variations de mouvement dans une direction horizontale ou une image ayant davantage de variations de mouvement dans une direction verticale, ou une image devant être faite tourner ou agrandie/réduite. En particulier, la présente invention porte sur un procédé de détermination adaptative d'une première composante à traiter en premier entre des composantes x et y d'un vecteur de mouvement d'une partition présente et un procédé de traitement d'une seconde composante à titre de composante restante du vecteur de mouvement à l'aide de la première composante du vecteur de mouvement traitée à l'avance.
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WO2017026681A1 (fr) * 2015-08-07 2017-02-16 엘지전자 주식회사 Procédé et dispositif d'interprédiction dans un système de codage vidéo
CN116193139A (zh) * 2020-06-05 2023-05-30 Oppo广东移动通信有限公司 帧间预测方法、解码器、编码器及计算机存储介质

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FR2725577B1 (fr) * 1994-10-10 1996-11-29 Thomson Consumer Electronics Procede de codage ou de decodage de vecteurs mouvement et dispositif de codage ou de decodage mettant en oeuvre ledit procede
KR100587561B1 (ko) * 2004-04-08 2006-06-08 삼성전자주식회사 모션 스케일러빌리티를 구현하는 방법 및 장치
FR2872974A1 (fr) * 2004-07-06 2006-01-13 Thomson Licensing Sa Procede ou dispositif de codage adaptatif

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WO2017026681A1 (fr) * 2015-08-07 2017-02-16 엘지전자 주식회사 Procédé et dispositif d'interprédiction dans un système de codage vidéo
US10582215B2 (en) 2015-08-07 2020-03-03 Lg Electronics Inc. Inter prediction method and apparatus in video coding system
US11122290B2 (en) 2015-08-07 2021-09-14 Lg Electronics Inc. Inter prediction method and apparatus in video coding system
US11503334B2 (en) 2015-08-07 2022-11-15 Lg Electronics Inc. Inter prediction method and apparatus in video coding system
US11902569B2 (en) 2015-08-07 2024-02-13 Lg Electronics Inc. Inter prediction method and apparatus in video coding system
CN116193139A (zh) * 2020-06-05 2023-05-30 Oppo广东移动通信有限公司 帧间预测方法、解码器、编码器及计算机存储介质

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