JP6740420B2 - Method and apparatus for coding/decoding motion vector based on reduced motion vector predictor candidate - Google Patents

Description

The present invention relates to a method and a device for coding/decoding a motion vector, and more particularly to a method and a device for predictive coding and predictive decoding of a motion vector of a current block.

MPEG (moving picture experts group)-4H. Codecs such as H.264/MPEG-4 AVC (advanced video coding) utilize motion vectors of previously encoded blocks adjacent to the current block to predict the motion vector of the current block. For the current block, the median of the motion vectors of the previously coded blocks adjacent to the left side, the upper side, and the upper right side is used as the motion vector predictor of the current block. The motion vector of the current block is not coded as it is, but only the motion vector difference between the motion vector of the current block and the predicted motion vector is coded.

One or more exemplary embodiments of the present invention provide a method and apparatus for predictive coding and predictive decoding of a motion vector, and a computer readable recording medium storing a program for performing the method. It is provided.

A method for encoding a motion vector according to an embodiment of the present invention to solve the technical problem is to estimate a motion vector of a current block and, based on the estimation result, among all candidates of a motion vector predictor, Determining a first motion vector predictor candidate as a motion vector predictor of the current block, and generating information about the motion vector based on the motion vector of the current block and the motion vector predictor of the current block; Of the overall candidates, a second motion vector predictor candidate and the difference vector are used to generate a virtual motion vector, and a difference vector between the virtual motion vector and each of the overall candidates is generated. And the information about the motion vector and selectively excluding the second motion vector predictor candidate from the overall candidates, information about the motion vector, and the motion vector predictor of the current block. Encoding the information.

A method of decoding a motion vector according to an exemplary embodiment of the present invention to solve the technical problem is to decode information about a motion vector of a current block, and select a predetermined motion vector from among all motion vector predictor candidates. Of the motion vector predictor candidate and the information about the decoded motion vector to generate a virtual motion vector, generate a difference vector between the virtual motion vector and each of the overall candidates, and Comparing the resulting difference vector with information about the decoded motion vector, selectively excluding the predetermined motion vector predictor from the overall candidate, and selecting a candidate motion vector predictor that has not been excluded. Determining one of them as a motion vector predictor of the current block, and restoring the motion vector of the current block based on the determined motion vector predictor and information about the decoded motion vector; ,including.

An apparatus for encoding a motion vector according to an embodiment of the present invention for solving the technical problem estimates a motion vector of a current block, and based on the estimation result, among all candidates of a motion vector predictor, Motion vector estimation that determines a first motion vector predictor candidate as the motion vector predictor of the current block, and generates information about the motion vector based on the motion vector of the current block and the motion vector predictor of the current block. A part of the whole candidates, a second motion vector predictor candidate and the difference vector are used to generate a virtual motion vector, and a difference vector between the virtual motion vector and each of the whole candidates is generated; A candidate determining unit that compares information about a difference vector and the motion vector and selectively excludes the second motion vector predictor candidate from the overall candidate; and information about the motion vector, and prediction of the current block. A motion vector estimator that encodes information about the motion vector.

An apparatus for decoding a motion vector according to an embodiment of the present invention for solving the above technical problem is a motion vector decoding unit for decoding information about a motion vector of a current block; Among them, a virtual motion vector is generated using a predetermined motion vector predictor candidate and information about the decoded motion vector, and a difference vector between the virtual motion vector and each of the overall candidates is generated. A candidate determination unit that compares the generated difference vector with information about the decoded motion vector and selectively excludes the predetermined motion vector predictor from the overall candidate; One of the motion vector candidates is determined as the motion vector predictor of the current block, and the motion vector of the current block is determined based on the determined motion vector predictor and the information about the decoded motion vector. A motion vector restoring unit for restoring the.

In order to solve the technical problem, the present invention provides a computer-readable recording medium having recorded therein a program for performing the method of encoding the motion vector and/or the method of decoding the motion vector.

According to the present invention, the number of motion vector predictor candidates is reduced and the motion vector is motion vector predictive coding and predictive decoding even when motion vector predictive coding and predictive decoding are performed using motion vector predictor candidates. can do. Therefore, of the motion vector predictor candidates, the information necessary to specify the motion vector predictor candidate used for prediction of the motion vector of the current block can be encoded with the minimum number of bits. The compression rate of /decoding is improved, and thus the compression rate of video encoding/decoding can be improved.

3 is a diagram illustrating a video encoding apparatus according to an exemplary embodiment of the present invention. 3 is a diagram illustrating a video decoding apparatus according to an exemplary embodiment of the present invention. 5 is a diagram illustrating a hierarchical coding unit according to an embodiment of the present invention. 4 is a diagram illustrating a video encoding unit based on an encoding unit according to an exemplary embodiment of the present invention. 6 is a diagram illustrating a video decoding unit based on a coding unit according to an embodiment of the present invention. 6 is a diagram illustrating a maximum coding unit, a sub-coding unit, and a prediction unit according to an embodiment of the present invention. 5 is a diagram illustrating a coding unit and a conversion unit according to an embodiment of the present invention. 6 is a diagram illustrating a division form of a coding unit, a prediction unit, and a conversion unit according to an embodiment of the present invention. 6 is a diagram illustrating a division form of a coding unit, a prediction unit, and a conversion unit according to an embodiment of the present invention. 6 is a diagram illustrating a division form of a coding unit, a prediction unit, and a conversion unit according to an embodiment of the present invention. 6 is a diagram illustrating a division form of a coding unit, a prediction unit, and a conversion unit according to an embodiment of the present invention. 6 is a diagram illustrating an apparatus for encoding a motion vector according to an exemplary embodiment of the present invention. 6 is a diagram illustrating candidates of a motion vector predictor according to an exemplary embodiment of the present invention. 6 is a diagram illustrating candidates of a motion vector predictor according to an exemplary embodiment of the present invention. 6 is a diagram illustrating blocks of various sizes adjacent to a current block according to an exemplary embodiment of the present invention. 6 is a diagram illustrating blocks of various sizes adjacent to a current block according to an exemplary embodiment of the present invention. 6 is a diagram illustrating blocks of various sizes adjacent to a current block according to an exemplary embodiment of the present invention. 6 is a diagram illustrating candidates of a motion vector predictor according to another embodiment of the present invention. 6 is a diagram illustrating candidates of a motion vector predictor according to another embodiment of the present invention. 6 is a diagram illustrating candidates of a motion vector predictor according to another embodiment of the present invention. 5 is a diagram illustrating a method of reducing a motion vector predictor candidate according to an embodiment of the present invention. 6 is a diagram illustrating a position of a current block included in an encoding unit having a predetermined size according to an exemplary embodiment of the present invention. 6 is a diagram illustrating a position of a current block included in an encoding unit having a predetermined size according to an exemplary embodiment of the present invention. 6 is a diagram illustrating a position of a current block included in an encoding unit having a predetermined size according to an exemplary embodiment of the present invention. 6 is a diagram illustrating a position of a current block included in an encoding unit having a predetermined size according to an exemplary embodiment of the present invention. 5 is a diagram illustrating an apparatus for decoding a motion vector according to an exemplary embodiment of the present invention. 6 is a flowchart illustrating a method of encoding a motion vector according to an exemplary embodiment of the present invention. 6 is a flowchart illustrating a method of decoding a motion vector according to an exemplary embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. An expression such as "at least one of" modifies the entire list of components, but not the individual components of the list, if it precedes the list of components.

Hereinafter, the image refers to a still image of the video, or a moving image and the video itself.

FIG. 1 illustrates a video encoding device according to an embodiment of the present invention. Referring to FIG. 1, a video coding apparatus 100 according to an exemplary embodiment of the present invention includes a maximum coding unit dividing unit 110, a coding depth determining unit 120, a video data coding unit 130, and a coding information coding unit 140. including.

The maximum coding unit dividing unit 110 may divide the current frame or the current slice based on the maximum coding unit which is the maximum size coding unit. The current frame or current slice may be divided into at least one maximum coding unit.

According to an embodiment of the present invention, the maximum coding unit and the depth may be used to represent the coding unit. As described above, the maximum coding unit indicates the coding unit having the largest size among the coding units of the current frame, and the depth indicates the degree to which the coding unit is hierarchically reduced. As the depth increases, the coding unit is reduced from the maximum coding unit to the minimum coding unit, the depth of the maximum coding unit is defined as the minimum depth, and the depth of the minimum coding unit is defined as the maximum depth. Also done. In the maximum coding unit, the size of each depth coding unit decreases as the depth increases, and the k-depth sub-coding unit may include a plurality of sub-coding units having a depth larger than k.

As the size of the frame to be coded increases, if the video is coded in a larger unit, the video can be coded at a higher video compression rate. However, if the encoding unit is increased and the size is fixed, it is impossible to efficiently encode the image by reflecting the continuously changing characteristic of the image.

For example, when coding a flat area related to the sea or the sky, the compression rate improves as the coding unit increases, but when coding a complicated area related to a person or a building, the coding unit decreases. The higher the compression rate, the better.

To this end, an embodiment of the present invention sets a maximum video coding unit of a different size for each frame or slice and sets a maximum depth. Since the maximum depth means the maximum number of times that the coding unit is reduced, the minimum coding unit size included in the maximum video coding unit can be variably set according to the maximum depth.

The coding depth determination unit 120 determines the maximum depth. The maximum depth is determined based on the RD cost (rate-distortion cost) calculation. The maximum depth may be determined differently for each frame or slice, or for each maximum coding unit. The determined maximum depth is output to the coding information coding unit 140, and the video data for each maximum coding unit is output to the video data coding unit 130.

The maximum depth means the minimum size coding unit included in the maximum coding unit, that is, the minimum coding unit. In other words, the maximum coding unit may be divided into sub-coding units of different sizes according to different depths. This will be described in detail later with reference to FIGS. 8A to 8D. In addition, sub-coding units having different sizes included in the maximum coding unit are predicted or converted based on processing units having different sizes. The transformation transforms pixel values in the spatial domain into coefficients in the frequency domain, and may be a discrete cosine transform or KLT (Karhunen Loever transform).

In other words, the video coding apparatus 100 may perform a plurality of processing steps for video coding based on processing units of various sizes and various forms. For encoding video data, processing steps such as prediction, conversion, and entropy coding are performed, but processing units of the same size are used in all steps, or processing units of different sizes are used for each step. You can also

For example, the video encoding device 100 can select a processing unit different from the encoding unit in order to predict a predetermined encoding unit.

When the size of the coding unit is 2Nx2N (where N is a positive constant), the processing unit for prediction is 2Nx2N, 2NxN, Nx2N, NxN, or the like. In other words, the motion estimation may be performed based on a processing unit in which at least one of the height and the width of the coding unit is halved. Hereinafter, the processing unit on which the prediction is based will be referred to as a “prediction unit”.

The prediction mode is at least one of an intra mode, an inter mode, and a skip mode, and the specific prediction mode may be performed only on a prediction unit having a specific size or shape. For example, the intra mode is performed only for a prediction unit having a square size of 2Nx2N, NxN. Also, the skip mode is performed only for a prediction unit of size 2Nx2N. If there are a plurality of prediction units inside a coding unit, prediction is performed for each prediction unit, and the prediction mode with the smallest coding error may be selected.

Also, the video encoding device 100 can convert the video data based on a processing unit having a size different from the encoding unit. In order to convert the coding unit, the conversion may be performed based on a data unit having a size smaller than or equal to the coding unit. Hereinafter, the processing unit that is the basis of conversion will be referred to as a “conversion unit”.

The coding depth determination unit 120 may use a Lagrangian multiplier-based rate-distortion optimization technique to determine a sub-coding unit included in the maximum coding unit. .. In other words, it is possible to determine in what form the maximum coding unit is divided into a plurality of sub-coding units, where the plurality of sub-coding units have different sizes depending on the depth. After that, the video data encoding unit 130 encodes the maximum encoding unit based on the division mode determined by the encoding depth determination unit 120 and outputs a bitstream.

The coding information coding unit 140 codes information about the coding mode of the maximum coding unit determined by the coding depth determination unit 120. The information about the division form of the maximum coding unit, the information about the maximum depth, and the information about the coding mode of the sub coding unit for each depth are coded, and a bitstream is output. The information about the coding mode of the sub coding unit may include information about the prediction unit of the sub coding unit, prediction mode information for each prediction unit, information about the conversion unit of the sub coding unit, and the like.

The information on the division form of the maximum coding unit may be information indicating division for each coding unit. For example, when the maximum coding unit is divided and coded, the information indicating the division is encoded with respect to the maximum coding unit, and the sub coding unit generated by dividing the maximum coding unit is further divided. Also in the case of encoding by means of information, information indicating division is encoded for each sub-encoding unit. The information indicating the division information may be flag information indicating the division information.

Since there are sub-coding units of different sizes for each maximum coding unit and the information about the coding mode has to be determined for each sub-coding unit, at least 1 for one maximum coding unit. Information about one coding mode is determined.

The video coding apparatus 100 can generate a sub-coding unit by halving the maximum coding unit in height and width as the depth increases. That is, if the size of a k-depth coding unit is 2Nx2N, the size of a k+1-depth coding unit is NxN.

Therefore, the image encoding apparatus 100 according to an embodiment may determine an optimal division mode for each maximum encoding unit based on the size and maximum depth of the maximum encoding unit in consideration of video characteristics. You can The size of the maximum coding unit is variably adjusted in consideration of the video characteristics, and the maximum coding unit is divided into sub-coding units of different depths to encode the video, thereby enabling the video with various resolutions. Can be encoded more efficiently.

FIG. 2 illustrates a video decoding apparatus according to an exemplary embodiment of the present invention. Referring to FIG. 2, a video decoding apparatus 200 according to an exemplary embodiment of the present invention includes a video data acquisition unit 210, a coded information extraction unit 220, and a video data decoding unit 230.

The video-related data acquisition unit 210 parses the bit stream received by the video decoding device 200, acquires video data for each maximum coding unit, and outputs the video data to the video data decoding unit 230. The image data acquisition unit 210 may extract information about the maximum coding unit of the current frame or slice from the header related to the current frame or slice. In other words, the bitstream is divided into maximum coding units, and the video data decoding unit 230 is caused to decode the video data for each maximum coding unit.

The coding information extraction unit 220 parses the bit string received by the video decoding apparatus 200, and determines from the header of the current frame the maximum coding unit, the maximum depth, the division form of the maximum coding unit, and the code of the sub-coding unit. Extract information about activation mode. Information about the division mode and the encoding mode is output to the video data decoding unit 230.

The information about the division form of the maximum coding unit may include information about sub-coding units of different sizes depending on the depth included in the maximum coding unit. As described above, the information on the division mode may be information (for example, flag information) indicating the division coded for each coding unit. The information about the coding mode may include information about the prediction unit for each sub-coding unit, information about the prediction mode, information about the transform unit, and the like.

The video data decoding unit 230 decodes the video data of each maximum coding unit based on the information extracted by the coding information extraction unit to restore the current frame.

The video data decoding unit 230 may decode the sub coding unit included in the maximum coding unit based on the information about the division form of the maximum coding unit. The decoding process may include an inter prediction process and an inverse transform process including intra prediction and motion compensation.

The video data decoding unit 230 may perform intra prediction or inter prediction based on the information about the prediction unit for each sub coding unit and the information about the prediction mode for the prediction of the sub coding unit. In addition, the video data decoding unit 230 can perform inverse conversion for each sub-encoding unit based on the information about the conversion unit of the sub-encoding unit.

FIG. 3 illustrates a hierarchical coding unit according to an embodiment of the present invention. Referring to FIG. 3, the hierarchical coding unit according to the present invention may include 32x32, 16x16, 8x8 and 4x4 from a coding unit having a width x height of 64x64. In addition to the square coding units, there may be coding units having a width x height of 64x32, 32x64, 32x16, 16x32, 16x8, 8x16, 8x4, 4x8.

Referring to FIG. 3, with respect to the video data 310 having a resolution of 1920×1080, the maximum coding unit size is set to 64×64 and the maximum depth is set to 2.

For other video data 320 having a resolution of 1920×1080, the maximum coding unit size is set to 64×64 and the maximum depth is set to 4. For the video data 330 having a resolution of 352x288, the maximum coding unit size is set to 16x16 and the maximum depth is set to 2.

When the resolution is high or the amount of data is large, it is desirable that the maximum encoding size is relatively large in order to accurately reflect the video characteristics as well as improving the compression rate. Therefore, the maximum encoding unit size of the video data 310 and 320 having a higher resolution than that of the video data 330 is selected as 64×64.

The maximum depth indicates the total number of layers in a hierarchical coding unit. Since the maximum depth of the video data 310 is 2, the coding unit 315 of the video data 310 has the major axis sizes of 32 and 16 as the depth increases from the maximum coding unit of the major axis size of 64. It may include a sub-coding unit.

On the other hand, since the maximum depth of the video data 330 is 2, the coding unit 335 of the video data 330 has a major axis size of 8 or 4 as the depth increases from the maximum coding unit of which the major axis size is 16. Up to the coding unit.

Since the maximum depth of the video data 320 is 4, the coding unit 325 of the video data 320 has the long axis size of 32, 16, 8 as the depth increases from the maximum coding unit of the long axis size of 64. 4 may be included. As the depth increases, the video is coded based on a smaller sub-coding unit, which is suitable for coding a video including a more detailed scene.

FIG. 4 illustrates a video coding unit based on a coding unit according to an embodiment of the present invention.

The intra prediction unit 410 performs intra prediction on the prediction unit of the intra mode in the current frame 405, and the motion estimation unit 420 and the motion compensation unit 425 determine the prediction unit of the inter mode on the current frame 405 and the reference frame. 495 is used to perform inter prediction and motion compensation.

A residual value is generated based on the prediction unit output from the intra prediction unit 410, the motion estimation unit 420, and the motion compensation unit 425, and the generated residual value is converted into the conversion unit 430 and the quantization unit 440. And is output as a quantized transform coefficient.

The quantized transform coefficient is restored to the residual value again through the inverse quantizer 460 and the inverse transform unit 470, and the restored residual value is post-processed through the deblocking unit 480 and the loop filtering 490. And output to the reference frame 495. The quantized transform coefficient is output to the bitstream 455 via the entropy coding unit 450.

An intra prediction unit 410, a motion estimation unit 420, a motion compensation unit 425, a conversion unit 430, and a quantization unit, which are components of the video encoding unit 400, are encoded by the video encoding method according to the embodiment of the present invention. 440, the entropy coding unit 450, the dequantization unit 460, the detransformation unit 470, the deblocking unit 480, and the loop filtering 490 are all set as the maximum coding unit, the subcoding unit by depth, the prediction unit, and the transform unit. Based on the above, the video encoding process is processed.

FIG. 5 illustrates a video decoding unit based on a coding unit according to an embodiment of the present invention.

The bit stream 505 passes through the parsing unit 510, and the coded video data to be decoded and the coding information necessary for decoding are parsed. The encoded video data is output as dequantized data via the entropy decoding unit 520 and the dequantization unit 530, and is restored to the residual value via the detransformation unit 540. The residual value is added to the intra prediction result of the intra prediction unit 550 or the motion compensation result of the motion compensation unit 560 to be restored for each coding unit. The restored coding unit is used for prediction of the next coding unit or the next frame after passing through the deblocking unit 570 and the loop filtering 580.

The parsing unit 510, the entropy decoding unit 520, the dequantization unit 530, the detransformation unit 540, and the intra, which are components of the video decoding unit 400, perform decoding by the video decoding method according to the embodiment of the present invention. The prediction unit 550, the motion compensation unit 560, the deblocking unit 570, and the loop filtering unit 580 process the video decoding process based on the maximum coding unit, the depth sub-coding unit, the prediction unit, and the transform unit. ..

In particular, the intra prediction unit 550 and the motion compensation unit 560 determine the prediction unit and the prediction mode in the sub coding unit in consideration of the maximum coding unit and the depth, and the inverse transform unit 540 determines the size of the transform unit. Considering the above, the inverse conversion is performed.

FIG. 6 illustrates a maximum coding unit, a sub-coding unit, and a prediction unit according to an embodiment of the present invention.

The video encoding apparatus 100 and the video decoding apparatus 200 according to an exemplary embodiment of the present invention use a hierarchical encoding unit to perform encoding/decoding in consideration of video characteristics. The maximum coding unit and the maximum depth may be set adaptively according to the characteristics of the image, or may be set variously according to the user's request.

A hierarchical structure 600 of coding units according to an exemplary embodiment of the present invention illustrates a case where the maximum coding unit 610 has a height and a width of 64 and a maximum depth of 4. The depth increases along the vertical axis of the hierarchical structure 600 of coding units, and the width increases and the height of the sub-coding units 620 to 650 is reduced. In addition, the prediction units of the maximum coding unit 610 and the sub-coding units 620 to 650 are illustrated along the horizontal axis of the hierarchical structure 600 of coding units.

The maximum coding unit 610 has a depth of 0 and a size of the coding unit, that is, a width and a height of 64x64. As the depth increases along the vertical axis, a depth 1 sub-coding unit 620 having a size 32x32, a depth 2 sub-coding unit 630 having a size 16x16, a depth 3 sub-coding unit 640 having a size 8x8, and a size There is a depth 4 sub-coding unit 650 that is 4x4. A sub-coding unit 650 having a size of 4x4 and a depth of 4 is a minimum coding unit.

Referring to FIG. 6, prediction units are illustrated along the horizontal axis for each depth. That is, the prediction unit of the maximum coding unit 610 of depth 0 is the same as or smaller than the coding unit 610 of size 64x64, the prediction unit 610 of size 64x64, the prediction unit 612 of size 64x32, and the size A 32x64 prediction unit 614 and a size 32x32 prediction unit (616 may be used.

The prediction unit of the coding unit 620 of size 32x32 at the depth 1 is the same as or smaller than the coding unit 620 of size 32x32, the prediction unit 620 of size 32x32, the prediction unit 622 of size 32x16, and the size The 16x32 prediction unit 624 and the size 16x16 prediction unit 626 may be used.

The prediction unit of the coding unit 630 of size 16x16 of depth 2 is the same as or smaller than the coding unit 630 of size 16x16, the prediction unit 630 of size 16x16, the prediction unit 632 of size 16x8, the size of The prediction unit 634 of 8×16 and the prediction unit 636 of size 8×8 may be used.

The prediction unit of the coding unit 640 of size 8x8 of depth 3 is the same as or smaller than the coding unit 640 of size 8x8, the prediction unit 640 of size 8x8, the prediction unit 642 of size 8x4, the size of The prediction unit 644 of 4×8 and the prediction unit 646 of size 4×4 may be used.

Finally, the size 4x4 coding unit 650 of depth 4 is the maximum depth coding unit, and the prediction unit is the prediction unit 650 of size 4x4. However, as the coding unit of the maximum depth, the coding unit and the prediction unit do not necessarily have to have the same size, and like the other coding units 610 to 650, they have a size smaller than that of the coding unit. The prediction can be performed by dividing the prediction unit into

FIG. 7 illustrates coding units and transform units according to an embodiment of the present invention.

The video encoding apparatus 100 and the video decoding apparatus 200 according to an exemplary embodiment of the present invention may perform maximum coding unit coding as it is, or may perform maximum coding in a sub coding unit that is smaller than or equal to the maximum coding unit. The unit is divided and encoded. During the encoding process, the size of the transform unit for the transform may also be selected to be the size for the highest compression rate regardless of the coding unit and the prediction unit. For example, when the current coding unit 710 has a size of 64x64, conversion may be performed using the conversion unit 720 having a size of 32x32.

8A to 8D illustrate division forms of a coding unit, a prediction unit, and a transform unit according to an embodiment of the present invention.
8A and 8B illustrate a coding unit and a prediction unit according to an embodiment of the present invention.

FIG. 8A illustrates a division mode selected by the video encoding apparatus 100 according to an exemplary embodiment of the present invention to encode the maximum coding unit 810. The video encoding apparatus 100 divides the maximum coding unit 810 into various forms, encodes the encoded units, compares the encoding results of various division forms based on the RD cost, and determines the optimal division form. select. When it is optimal to directly code the maximum coding unit 810, the maximum coding unit 800 may be coded without dividing the maximum coding unit 810 as shown in FIGS. 8A to 8D. it can.

Referring to FIG. 8A, a maximum coding unit 810 having a depth of 0 is divided into sub coding units having a depth of 1 or more and coded. After the maximum coding unit 810 is divided into four depth-1 sub-coding units, all or some of the depth-1 sub-coding units are further divided into depth-2 sub-coding units.

Among the sub-encoding units with a depth of 1, the sub-encoding unit located on the upper right side and the sub-encoding unit located on the lower left side were divided into sub-encoding units with a depth of 2 or more. Some of the sub-coding units with a depth of 2 or more may be further divided into sub-coding units with a depth of 3 or more.

FIG. 8B illustrates a division mode of a prediction unit related to the maximum coding unit 810. Referring to FIG. 8B, the prediction unit 860 related to the maximum coding unit is divided differently from the maximum coding unit 810. In other words, the prediction unit for each sub-coding unit is smaller than the sub-coding unit.

For example, the prediction unit related to the sub coding unit 854 located on the lower right side of the sub coding units of depth 1 may be smaller than the sub coding unit 854. The prediction units related to some of the sub coding units 815, 816, 850, 852 of the depth 2 sub coding units 814, 816, 818, 828, 850, 852 may be smaller than the sub coding units.

Further, the prediction unit related to the sub-coding units 822, 832, 848 of depth 3 may be smaller than the sub-coding unit. The prediction unit is in a form in which each sub-coding unit is halved in the height or width direction, or in a form in which it is divided in the height and width directions.

8C and 8D illustrate prediction units and conversion units according to an embodiment of the present invention.

FIG. 8C illustrates a division form of a prediction unit related to the maximum coding unit 810 illustrated in FIG. 8B, and FIG. 8D illustrates a division form of a conversion unit of the maximum coding unit 810.

Referring to FIG. 8D, the division mode of the conversion unit 870 may be set differently from the prediction unit 860.

For example, even if the prediction unit related to the coding unit 854 of the depth 1 is selected in a form in which the height is halved, the transform unit may be selected to have the same size as the size of the coding unit 854 of the depth 1. .. Similarly, even if the prediction unit related to the coding unit 814, 850 of the depth 2 is selected in the form in which the height of the coding unit 814, 850 of the depth 2 is halved, the conversion unit is the coding of the depth 2 coding unit. The size may be selected to be equal to the original size of the units 814 and 850.

The conversion unit may be selected to have a size smaller than the prediction unit. For example, when the prediction unit related to the coding unit 852 having the depth of 2 is selected to have a half width, the conversion unit has a height and width that are smaller than the prediction unit. Will also be selected.

FIG. 9 illustrates an apparatus for encoding a motion vector according to an embodiment of the present invention.

An apparatus included in the video encoding apparatus 100 of FIG. 1 or the video encoding unit 400 of FIG. 4 and encoding a motion vector is illustrated in detail in FIG. Referring to FIG. 9, a motion vector encoding apparatus 900 according to an exemplary embodiment of the present invention includes a motion vector estimating unit 910, a candidate determining unit 920, and a motion vector encoding unit 930.

In order to decode a block coded using inter prediction, that is, temporal prediction, information about a motion vector indicating a relative position difference between a current block and a similar block in a reference picture is used. is necessary. Therefore, at the time of video coding, the information about the motion vector is coded and inserted into the bitstream. However, if the information about the motion vector is coded and inserted as it is, the overhead for coding the information about the motion vector ( overhead) increases and the compression rate of video data decreases.

Therefore, in video coding, the motion vector of the current block is predicted, and only the motion vector difference between the motion vector predictor generated as a result of the prediction and the original motion vector is coded. Information about the motion vector is also compressed by inserting it into the bitstream.

The motion vector predictive coding may include an explicit mode and an implicit mode.

MPEG-4 H.264. Codecs such as H.264/MPEG-4 AVC (advanced video coding) utilize motion vectors of previously encoded blocks adjacent to the current block to predict the motion vector of the current block. The median of the motion vectors of the previously coded blocks adjacent to the left side, the upper side and the right side of the current block is used as the motion vector predictor of the current block. Since the motion vectors of all blocks coded using inter prediction are predicted using the same method, it is not necessary to separately code the information about the motion vector predictor of the current block. However, the video encoding apparatus 100 or the video encoding unit 400 according to the present invention, in order to predict the motion vector more accurately, an implicit mode in which the information about the motion vector predictor is not separately encoded, And the explicit mode of encoding information about the motion vector predictor. The explicit mode means a mode in which, of a plurality of motion vector predictor candidates, information about the motion vector predictor used for the motion vector predictor of the current block is coded and inserted as a sequence parameter, slice parameter, or block parameter in the bitstream. To do.

FIG. 9 illustrates an apparatus for performing predictive coding when a motion vector is coded by such an explicit mode. The motion vector estimation unit 910 estimates the motion vector of the current block. A block similar or identical to the current block is searched with at least one reference picture, and a motion vector, which is a relative position difference between the current block and the searched reference block, is estimated based on the search result. A block similar or identical to the current block can be searched based on the calculation of SAD (sum of absolute difference), and the motion vector of the current block can be estimated based on the search result.

Also, the motion vector estimation unit 910 predicts the motion vector of the current block based on the motion vector of the block included in the previously coded area adjacent to the current block. In other words, the motion vector of the block included in the previously coded area adjacent to the current block is set as the candidate of the motion vector predictor (candidates), and the estimated current block of the candidates of the motion vector predictor is set. The motion vector predictor candidate that is most similar to the motion vector is determined.

MPEG-4 H.264. In codecs such as H.264/MPEG-4 AVC, the median value of motion vectors of previously encoded blocks adjacent to the left side, the upper side, and the upper right side of the current block is used as a prediction motion vector of the current block. Since all the blocks to be coded are predicted using the motion vector of the previously coded block and only one motion vector predictor is used, the information about the motion vector predictor needs to be coded separately. There is no. In other words, there is one motion vector predictor for a block coded using inter prediction.

However, if the motion vector of the current block is more accurately predicted, the motion vector can be coded at a higher compression rate. By selecting one of the candidates and using it as the motion vector predictor of the current block, the motion vector of the current block is encoded at a higher compression rate. Hereinafter, a method of encoding a motion vector of the current block using a plurality of motion vector predictor candidates will be described in more detail.

10A and 10B illustrate motion vector predictor candidates according to an embodiment of the present invention.

Referring to FIG. 10A, a method of predicting a motion vector according to an exemplary embodiment of the present invention uses one of motion vectors of previously encoded blocks adjacent to a current block as a motion vector predictor of a current block. can do. Of the blocks adjacent to the upper part of the current block, the leftmost a0 block, the leftmost uppermost b0 block, the right upper adjacent c block, the left upper adjacent d block, and the left lower e adjacent block. Any of the motion vectors of can be used as candidates for the motion vector predictor of the current block.

A video encoding method and a video decoding method according to the present invention perform video encoding and decoding on the basis of encoding units of various sizes that are divided according to depth. Vectors can also be used as motion vector predictor candidates.

Referring to FIGS. 8A and 8B, if the current block is a coding unit 820, the coding units 814, 816, 818 of the upper, left upper, right upper, left and lower left of the current block are: 822 is encoded before the current block. Therefore, the motion vector of the block adjacent to the lower left part of the current block can also be used as a motion vector predictor candidate.

Referring to FIG. 10B, the motion vectors of all the blocks which the current block is in contact with can be used as candidates for the motion vector predictor. In other words, not only the leftmost a0 block among the blocks adjacent to the upper part but also the motion vectors of all the blocks adjacent to the upper part (a0 to aN) can be used as the motion vector predictor candidates, Of the above blocks, not only the uppermost b0 block but also the motion vectors of all the blocks adjacent to the left side (b0 to bN) can be used as the motion vector predictor candidates.

Further, the median value of motion vectors of adjacent blocks can be used as a motion vector predictor candidate. In other words, median(mv_a0, mv_b0, mv_c) can be used as a motion vector predictor candidate of the current block. Here, mv_a0 is the motion vector of the a0 block, mv_b0 is the motion vector of the b0 block, and mv_c is the motion vector of the c block.

However, the candidates of the motion vector predictor of the current block may be limited according to the size of the current block and the size of the adjacent block, which will be described in detail with reference to FIGS. 10C to 10E.

10C through 10E illustrate blocks of various sizes adjacent to a current block according to an exemplary embodiment of the present invention.

As described above, the image encoding method and the image decoding method according to the present invention encode an image using encoding units and prediction units having various sizes determined by depth. Therefore, the size of the block adjacent to the current block is also diverse, but if the size of the current block and the size of the partially adjacent block are significantly different, the motion vectors of the partially adjacent blocks having different sizes are May not be used as a motion vector predictor candidate.

Referring to FIG. 10C, blocks 1014 to 1018 adjacent to the top of the current block 1010 are blocks smaller than the size of the current block 1010. Since there is a high possibility that the motion vector of the adjacent block 1012 having the same size as the current block 1010 is the same as or similar to the motion vector of the current block 1010, the motion vector estimation unit 910 determines that the motion vector estimation unit 910 has the same size. Only the motion vector of the adjacent block 1012 can be used as a motion vector predictor candidate.

Even if the sizes are not the same, only motion vectors of adjacent blocks of a predetermined size or more can be used as motion vector predictor candidates. For example, compared with the size of the current block 1010, only motion vectors of blocks (1012 and 1018) having a size of ¼ or more can be used as motion vector predictor candidates.

Referring to FIG. 10D, the size of the block 1022 adjacent to the left side of the current block 1020 is 16 times the size of the current block, and there is a significant difference in size. Due to significant size differences, the motion vector of the block 1022 adjacent to the left may not be the same or similar to the motion vector of the current block 1020. Therefore, the motion vector of the block 1022 adjacent to the left side is not used as the motion vector predictor candidate of the current block 1020, but only the motion vectors of the block 1024 adjacent to the upper part and the block 1026 adjacent to the left upper part are used as the motion vector predictor candidates. can do.

Referring to FIG. 10E, the size of the current block (1030 is larger than the sizes of all the adjacent blocks 1031 to 1037. At this time, the motion vectors of all the adjacent blocks 1031 to 1037 are set to the current block 1030. The number of motion vector predictor candidates of the current block 1030 is too large when used as the motion vector predictor candidates of the current block 1030. The larger the size difference between the current block 1030 and the adjacent blocks 1031 to 1037, the more motion vector candidate candidates. Therefore, the motion vector estimation unit 910 according to the embodiment of the present invention does not use the motion vectors of some of the adjacent blocks as the motion vector predictor candidates of the current block 1030.

For example, in the embodiment illustrated in FIG. 10E, the motion vectors of the block 1031 adjacent to the lower left side and the block 1037 adjacent to the upper right side may not be used as the motion vector predictor candidate of the current block 1030.

This is further generalized, and if the size of the current block 1030 is equal to or larger than a predetermined size, the motion vector of the block adjacent to the specific direction among the adjacent blocks is not used as the motion vector predictor candidate of the current block 1030. Sometimes.

11A through 11C illustrate motion vector predictor candidates according to another embodiment of the present invention.

FIG. 11A illustrates a method of determining a motion vector predictor candidate of a B-picture (bi-directional predictive picture) according to an embodiment of the present invention. When the current picture including the current block is a B picture for which bidirectional prediction is performed, a motion vector generated based on a temporal distance may be a motion vector predictor candidate.

The motion vector predictor candidate (mv_temporal) of the current block 1100 of the current picture 1110 is determined using the motion vector of the block 1120 that is colocated with the temporally preceding picture 1112. For example, if the motion vector mv_colA of the block 1120 at the same position as the current block 1100 is generated for the searched block 1122 of the temporally subsequent picture 1114 of the current picture 1110, the motion vector predictor of the current block 1100 is predicted. The candidates mv_L0A and mv_L1A are determined as follows.

mv_L1A=(t1/t2)*mv_colA
mv_L0A=mv_L1A-mv_colA
Here, mv_L0A means a motion vector predictor candidate of the current block 1110 related to the temporally preceding picture 1112, and mv_L1A means a motion vector predictor candidate of the current block 1110 related to the temporally subsequent picture 1114. To do.

In the embodiment illustrated in FIG. 11A, a B picture, the current picture 1110, exists between a temporally preceding picture 1112 and a temporally subsequent picture 1114. At this time, if the motion vector mv_colA of the block 1120 at the same position is generated for the temporally subsequent picture 1114 of the current picture 1110, the motion vector of the current block 1100 is more accurately predicted based on mv_L1A. can do. In other words, when mv_colA is a motion vector in the direction opposite to the direction shown in FIG. 11A, that is, when mv_colA is generated for another picture before the picture 1112 that precedes in time, mv_colA is smaller than that in FIG. The motion vector of the current block 1100 can be predicted more accurately if the motion vector is in the direction shown in FIG. 11A.

Therefore, if the direction from the current block 1110 to the block 1120 at the same position is the List0 direction, the motion vector mv_colA of the block 1120 at the same position is in the List1 direction only as shown in FIG. 11A. The current picture 1110 is more likely to exist between the preceding picture 1112 and the following picture 1114, and the motion vector of the current block 1100 can be predicted more accurately based on mv_colA.

In addition, since the pictures 1110 to 1114 illustrated in FIG. 11A are arranged over time, a motion vector predictor candidate (mv_temporal) of the current block can be generated based on the POC (picture order count). Since the picture referred to by the current block may be a picture other than the adjacent pictures 1112 and 1114 illustrated in FIG. 11A, the motion vector predictor candidate of the current block is generated based on the POC.

For example, if the POC of the current picture is CurrPOC and the POC of the picture referred to by the current picture is CurrRefPOC, the motion vector predictor candidate of the current block is also generated as follows.

Scale=(CurrPOC-CurrRefPOC)/(ColPOC-ColRefPOC)
mv_temporal=Scale*mv_colA
Here, ColPOC is the POC of the picture 1112 that temporally precedes the block 1120 that includes the same position, and ColRefPOC that temporally follows the block 1122 that the block 1120 that includes the same position refers to. This is the POC of the picture 1114 to be executed.

FIG. 11B illustrates a method of generating motion vector predictor candidates for a B picture according to another embodiment of the present invention. Compared with the method illustrated in FIG. 11A, a difference is that a picture 1114 that is temporally subsequent includes a block at the same position as the current block 1100.

Referring to FIG. 11B, the motion vector predictor candidate of the current block 1100 of the current picture 1110 may be generated using the motion vector of the block 1130 at the same position as the temporally subsequent picture 1114. For example, if the motion vector mv_colB of the block 1130 at the same position as the current block 1100 is generated for the searched block 1132 of the temporally preceding picture 1112 of the current picture 1110, the predicted motion vector of the current block 1100 is calculated. The candidates mv_L0B and mv_L1B may also be generated as follows.

mv_L0B=(t3/t4)*mv_colB
mv_L1B=mv_L0B-mv_colB
Here, mv_L0B means a motion vector predictor of the current block 1110 related to the temporally preceding picture 1112, and mv_L1B means a motion vector predictor candidate of the current block 1100 related to the temporally subsequent picture 1114. ..

Similar to FIG. 11A, in the embodiment shown in FIG. 11B, the B picture, the current picture 1110, exists between the temporally preceding picture 1112 and the temporally subsequent picture 1114. Therefore, if the motion vector mv_colB of the block 1130 at the same position is generated for the temporally preceding picture 1112, the motion vector of the current block 1100 can be predicted more accurately based on mv_L0B. In other words, when mv_colB is a motion vector in the direction opposite to the direction shown in FIG. 11B, that is, when mv_colB is generated for another picture after the picture 1114 that follows in time, mv_colB is calculated. 11B, the motion vector of the current block 1100 can be predicted more accurately.

Therefore, if the direction from the current block 1110 to the block 1130 at the same position is the List1 direction, the motion vector mv_colB of the block 1130 at the same position is in the List0 direction, as shown in FIG. 11B. The current picture 1110 is more likely to exist between the preceding picture 1112 and the following picture 1114, and the motion vector of the current block 1100 can be predicted more accurately based on mv_colB.

In addition, since the picture referred to by the current block may be a picture other than the adjacent pictures 1112 and 1114 illustrated in FIG. 11B, a motion vector predictor candidate for the current block is generated based on the POC.

For example, if the POC of the current picture is CurrPOC and the POC of the picture referred to by the current picture is CurrRefPOC, the motion vector predictor candidate of the current block is also generated as follows.

Scale=(CurrPOC-CurrRefPOC)/(ColPOC-ColRefPOC)
mv_temporal=Scale*mv_colB
Here, ColPOC is the POC of the picture 1114 that includes the block 1130 at the same position and is temporally subsequent, and ColRefPOC is the time that includes the block 1132 referenced by the block 1130 at the same position. It is the POC of the preceding picture 1112.

FIG. 11C illustrates a motion vector predictor candidate of a P picture (predictive picture) according to an embodiment of the present invention. Referring to FIG. 11C, the motion vector predictor candidate of the current block 1100 of the current picture 1110 is determined using the motion vector of the block 1140 at the same position as the temporally preceding picture 1112. For example, if the motion vector mv_colC of the block 1140 at the same position as the current block 1100 is generated for the searched block 1142 of another temporally preceding picture 1116, it is a candidate motion vector predictor of the current block 1100. mv_L0C is determined as follows.

mv_L0C=(t6/t5)*mv_colC
As described in connection with FIGS. 11A and 11B, mv_L0C can be determined based on the POC. The mv_L0C can be determined based on the POC of the current picture 1110, the POC of the picture referenced by the current picture 1110, the POC of the temporally preceding picture 1112, and the POC of the other temporally preceding picture 1116.

Since the current picture 1110 is a P picture, only one motion vector predictor candidate of the current block 1100 is determined, unlike FIGS. 11A and 11B.

In addition, in FIGS. 11A and 11B, in order to use the motion vector predictor candidate generated based on the temporal distance to predict the motion vector of the current block, one of the blocks 1120 and 1130 at the same position is used. The information indicating whether to generate a motion vector predictor candidate using the blocks of 1 must be coded together, and this information is included in the slice header or the sequence header as a slice parameter or a sequence parameter.

In summary, referring to FIGS. 10A and 10B and FIGS. 11A to 11C, the set C of motion vector predictor candidates is as follows.

C={median(mv_a0, mv_b0, mv_c), mv_a0, mv_a1,..., mv_aN, mv_b0, mv_b1,..., mv_bN, mv_c, mv_d, mv_e, mv_temporal}
Alternatively, the set C may be a set in which the number of motion vector predictor candidates is reduced.

C={median(mv_a', mv_b', mv_c'), mv_a', mv_b', mv_c', mv_temporal}
Here, mv_x means a motion vector of x block, median() means a median value, and mv_temporal is a prediction generated using the temporal distance described in connection with FIGS. 11A to 11C. It means a motion vector candidate. mv_a′ means a valid first motion vector of mv_a0, mv_a1,..., Mv_aN. For example, if the a0 block is coded using intra prediction or refers to a picture different from the current block, the motion vector of a0, mv_a0, is not valid, so mv_a'=mv_a1. , A1 block motion vector is also invalid, mv_a′=mv_a2. Similarly, mv_b′ means a valid first motion vector of mv_b0, mv_b1,..., Mv_bN, and mv_c′ means a valid first motion vector of mv_c, mv_d, mv_e.

Among the motion vectors of the blocks adjacent to the current block, the motion vector of the block that refers to a picture different from the current block cannot efficiently predict the motion vector of the current block. Therefore, in the set C of motion vector predictor candidates, a motion vector of a block that refers to a picture different from the current block can be excluded.

When the motion vector coding apparatus 900 codes a motion vector in the explicit mode, the motion vector coding apparatus 900 indicates which prediction motion vector candidate in the C set was used to predict the motion vector of the current block (signaling). ) Information is also encoded together. In other words, when the motion vector encoding apparatus 900 encodes a motion vector, a binary number corresponding to each element of the C set, that is, each candidate of the motion vector predictor is assigned and used to predict the motion vector of the current block. The binary number corresponding to the selected motion vector predictor candidate is also encoded.

In order to specify one of the elements of the C set, a binary number corresponding to each motion vector predictor candidate is assigned and the binary number is output. Therefore, the smaller the number of elements of the C set, the smaller the bit number of the elements. The elements of the C set can be specified by a base number.

Therefore, if there is a motion vector predictor candidate that is duplicated in the C set, the motion vector predictor candidate that is duplicated can be excluded from the C set and a binary number can be assigned. For example, when the C set is C={median(mv_a', mv_b', mv_c'), mv_a', mv_b', mv_c', mv_temporal} as described above, mv_a', mv_b' and mv_c' are If both are the same, the C set can be determined by two elements and assigned a binary number, such as C={mv_a', mv_temporal}. If 5 elements of the C set can be identified using 3 bits before excluding the overlapping motion vector predictor candidates, then 2 elements are excluded after excluding the overlapping motion vector predictor candidates. Element can be specified by using 1 bit.

Instead of excluding the overlapping motion vector predictor candidates, a predetermined weight may be added to increase the probability that the overlapping motion vector predictor candidates will be determined as the motion vector predictor of the current block. it can. In the above example, mv_a′, mv_b′ and mv_c′ are all the same and only mv_a′ is included in the C set. Therefore, a predetermined weighting value is added to mv_a′ and mv_a′ is the motion vector of the current block. The probability of being used to predict

In addition, when the number of motion vector predictor candidates is one, the binary number for specifying one of the motion vector predictor candidates may not be encoded. For example, the C set is C={median(mv_a0, mv_b0, mv_c), mv_a0, mv_a1,..., Mv_aN, mv_b0, mv_b1,... If the bN block, the c block, the d block, and the e block are all intra-predicted blocks, the C set has C={mv_temporal}, and thus substantially includes only one element. Therefore, in this case, the motion vector coding apparatus 900 may not code the binary number for specifying one of the motion vector predictor candidates.

A person skilled in the art to which the present invention pertains can easily understand that, in addition to all of the above motion vector predictor candidates, other motion vectors are used as motion vector predictor candidates. Will.

In addition, according to another embodiment of the present invention, the candidate determination unit 920 may reduce the number of motion vector predictor candidates.

As described above, in order to identify the motion vector predictor candidate used to predict the motion vector of the current block among the plurality of motion vector predictor candidates, additional information is encoded and included in the bitstream. Be done. Therefore, as the number of elements in the C set is smaller, the information necessary for specifying the motion vector predictor candidate used to predict the motion vector of the current block in the C set may be encoded with fewer bits. To do. Therefore, the candidate determination unit 920 can selectively exclude a predetermined motion vector predictor candidate from all motion vector predictor candidates using a predetermined evaluation function. This will be described in detail with reference to FIG.

FIG. 12 illustrates a method of reducing motion vector predictor candidates according to an embodiment of the present invention. In FIG. 12, it is assumed that the number of elements of the C set is three, MVP1, MVP2, and MVP3 are the elements of the C set, and the motion vector of the current block is MV. Since the motion vector predictor candidate most similar to the motion vector of the current block is used to predict the motion vector of the current block, MVP3 most similar to MV is used to predict the motion vector of the current block. It

Therefore, in the motion vector encoding apparatus 900, the difference vector between the motion vector of the current block encoded as information about the motion vector and the motion vector predictor candidate used to predict the motion vector of the current block (hereinafter , "Actual motion vector difference") is (2,0). Since the MV is (5,0) and the MVP3 is (3,0), the actual motion vector difference is (2,0).

The candidate determination unit 920 selectively excludes at least one motion vector predictor candidate among all motion vector predictor candidates using the actual motion vector difference and the predetermined evaluation function. More specifically, a virtual motion vector is generated using the actual motion vector difference and a predetermined motion vector predictor candidate, and the motion vector difference between the generated virtual motion vector and the overall candidate (hereinafter, “Virtual motion vector difference”) is generated for all candidates. A virtual motion vector is generated by adding the actual motion vector difference and a predetermined motion vector predictor candidate, and the motion vector difference between the generated virtual motion vector and the overall candidate is calculated. By comparing the actual motion vector difference and the virtual motion vector difference calculated for each overall candidate, the predetermined motion vector predictor candidate can be selectively excluded from the overall motion vector predictor candidates.

More specifically, with reference to FIG. 12, the candidate determination unit 920 first determines whether or not to exclude MVP1, which is one of the motion vector predictor candidates, from the overall candidates.

If the virtual motion vector difference generated by subtracting the motion vector predictor candidate that is different from the virtual motion vector based on MVP1 is smaller than the actual motion vector difference, MVP1 is used to predict the motion vector of the current block. Not done. For example, if the virtual motion vector difference generated by subtracting MVP3 from the virtual motion vector generated by adding MVP1 and the actual motion vector difference is smaller than the actual motion vector difference, MVP3 is larger than MVP1. This is because by predicting the virtual motion vector more accurately, it is clear that in this case, MVP1 cannot be the motion vector predictor.

In FIG. 12, if MVP1 and the actual motion vector difference are added, the virtual motion vector based on MVP1 is (2,0). Therefore, when a virtual motion vector is generated based on MVP1, the virtual motion vector difference related to MVP2 is (2,0), and the virtual motion vector difference related to MVP3 is (-1,0). Is. At this time, since the magnitude of the virtual motion vector difference (-1,0) related to the MVP3 is smaller than the magnitude of the actual motion vector difference (2,0), the MVP1 uses the predicted motion of the current block. Cannot be a vector. Therefore, MVP1 can be excluded from all candidates for motion vector predictors. In other words, the motion vector predictor candidate corresponding to MVP1 in the aforementioned C set may be excluded.

At this time, the virtual motion vector difference calculated for the MVP1 itself is (2, 0), and since it is always the same as the actual motion vector difference, it does not become smaller than the size of the actual motion vector. Therefore, when calculating the virtual motion vector difference for each of all candidates of the motion vector predictor, the virtual motion vector difference relating to the MVP1 itself is not calculated.

When the determination as to whether to exclude MVP1 is completed, the candidate determination unit 920 determines whether to exclude MVP2 from all candidates for the motion vector predictor. If MVP2 is added to the actual motion vector difference, the virtual motion vector based on MVP2 is (2,0). Therefore, the virtual motion vector difference related to MVP1 is (2,0), and the virtual motion vector difference related to MVP3 is (-1,0). Since the magnitude of the virtual motion vector difference related to MVP3 is smaller than the magnitude of the actual motion vector difference, MVP2 is excluded from the overall candidates for the motion vector predictor, like MVP1. When determining whether to exclude MVP2, the comparison between the virtual motion vector difference relating to MVP1 and the actual motion vector difference is selective. Since it is determined that MVP1 is not already the motion vector predictor of the current block, it is possible to compare the virtual motion vector difference of each of the remaining candidates excluding MVP1 with the actual motion vector difference. it can.

The candidate determination unit 920 also determines whether to exclude MVP3. The virtual motion vector based on MVP3 is the same as the actual motion vector, and is smaller than the actual motion vector difference even if other predicted motion vector candidates (that is, MVP1 or MVP2) are subtracted from the actual motion vector. Since the virtual motion vector difference does not occur, the MVP3 is not excluded from all the motion vector predictor candidates. In addition, according to another embodiment of the present invention, it is clear that the MVP3 determined to be used to predict the motion vector of the current block is not excluded from the overall motion vector predictor candidates. The determining unit 920 may skip the exclusion of the motion vector predictor candidate determined to be used to predict the motion vector of the current block.

In short, the candidate determination unit 920 determines whether to exclude the second motion vector predictor, which is one of all motion vector predictor candidates, by adding the second motion vector predictor and the actual motion vector difference, A virtual motion vector is generated, a difference vector of a predicted motion vector different from the virtual motion vector is calculated for each of all candidates, and a plurality of virtual motion vector differences is generated. If there is at least one virtual motion vector difference that is smaller than the actual motion vector difference among the plurality of virtual motion vector differences, the second motion vector predictor is not the motion vector predictor of the current block. Since it is obvious, it is excluded from the overall candidates for the motion vector predictor.

Further, the candidate determination unit 920 reduces the total number of motion vector predictor candidates, that is, the number of elements of the C set, by repeating such determination regarding exclusion as to all motion vector predictor candidates. be able to. Exclusion is determined in order according to the alignment order of the candidates of the overall motion vector predictor of the C set. For example, when C={median(mv_a', mv_b', mv_c'), mv_a', mv_b', mv_c', mv_temporal}, it is determined whether median(mv_a', mv_b', mv_') is excluded, When the judgment is completed, the exclusion of mv_a' is judged. Then, the exclusion of mv_b' is determined. The exclusion determination is repeated up to mv_temporal according to the order of the C sets.

When iteratively judging, it is possible to omit the comparison between the virtual motion vector difference and the actual motion vector difference for the candidates excluded in the previous judgment process, which is explained in connection with the judgment of the exclusion of MVP2. As I did.

In addition, the C set is rearranged according to a predetermined criterion, as will be described later with reference to FIGS. 13A to 13D. However, when the C set is rearranged, the C set is excluded according to the rearranged order. Repeat the judgment of.

The magnitude comparison between the virtual motion vector difference and the actual motion vector difference described with reference to FIG. 12 is applied to the two-dimensional motion vector as well as the one-dimensional motion vector. In other words, by comparing the magnitude of the virtual motion vector difference defined by the x-coordinate and the y-coordinate with the magnitude of the actual motion vector difference, it is possible to selectively exclude a predetermined motion vector predictor candidate from all candidates. it can.

However, the magnitude that is a criterion for comparing the virtual motion vector difference and the actual motion vector difference is merely an example, and various criteria may be used as the criterion. Also used for comparison with. When an evaluation function for generating a value related to the virtual motion vector difference and a value related to the actual motion vector difference based on a predetermined criterion is “A”, the virtual motion vector difference is calculated by the following mathematical expression (1). And the actual motion vector difference can be compared.

A(mvx+MVD-mvy)<A(MVD) (1)
The candidate determination unit 920 satisfies “mvy” that satisfies Expression (1) in order to determine whether or not to exclude “mvx”, which is one of the overall motion vector predictor candidates, from the overall motion vector predictor candidates. , Is present in the overall candidates. In Expression (1), “MVD” means an actual motion vector difference. In order to determine whether “mvx” is excluded, a virtual motion vector difference “mvx+MVD−” that is a different motion vector predictor candidate “mvy” from the virtual motion vector “mvx+MVD” based on “mvx”. “Mvy” is a value evaluated using a predetermined evaluation function “A”, “A(mvx+MVD−mvy)” is calculated, and the value generated as a result of the calculation is a value related to the actual motion vector difference. Compare with a certain "A (MVD)". Of the overall candidates, other motion vector predictor candidates excluding “mvx” are iteratively substituted into “mvy”, and at least one “mvy” satisfying Expression (1) exists in the overall candidates. Determine whether or not.

As described above, the virtual motion vector difference and the actual motion vector difference evaluated by "A" may be defined by the x coordinate and the y coordinate. In this case, the evaluation function may be defined as the sum of the value evaluated for the x coordinate and the value evaluated for the y coordinate, as in the following Expression (2).

A(p,q)=f(p)+f(q) (2)
When the virtual motion vector difference or the actual motion vector difference is defined as the x-coordinate “p” and the y-coordinate “q”, the respective coordinate values are substituted into a predetermined function “f”, and the sum of the substituted results is used. , The evaluation function “A” is also defined.

According to an embodiment of the present invention, the evaluation function “A” in Equations (1) and (2) may be the result of entropy coding the virtual motion vector difference and the result of entropy coding the actual motion vector difference. Is an evaluation function for estimating and. The candidate determination unit 920 estimates the result of entropy-encoding the virtual motion vector difference and the actual motion vector difference based on the evaluation function “A”, and reduces the number of motion vector predictor candidates based on the estimation result. be able to. This will be described in detail with reference to the equation (3).

Length=1;
Temp=(val<=0(-val<<1)+1:(val<<1);
While(1!=Temp){
Temp>>=1;
Length+=2;
}
f(val)=Length (3)
The function “f” for estimating the entropy coding result with respect to the x coordinate value or the y coordinate value may be defined as Equation (3). If variable length coding (eg, a variable “f” that predicts a universal variable length coding result is input with “val” that is an x coordinate value or ay coordinate value) “Length” is calculated by the above equation (3).

Equation (3) can also be expressed as follows.

The x-coordinate value or the y-coordinate value may be the x-coordinate value or the y-coordinate value of the virtual motion vector difference or the actual motion vector difference.

According to Equation (3), if “val” is a negative number or “0”, “val” is converted to a positive number, then shifted leftward by about 1 bit, and the coordinate value is multiplied by “2”, Add "1" and save as "Temp". If "val" is a positive number, "val" is shifted to the left by about 1 bit, the coordinate value is multiplied by "2", and the result is stored as "Temp". After that, the “while” loop is repeated until “Temp” becomes “1”, and “Length” is calculated.

For example, if the virtual motion vector difference or the actual motion vector difference is (2,0), A(2,0)=f(2+f(0).

f(2) is calculated as follows. Since "2" of f(2) is a positive number, it is shifted to the left by about 1 bit and "Temp" is set to "4". In the first while loop, "Temp" is "4", and "4" is not "1". Therefore, "4" is shifted to the right and multiplied by "1/2" to obtain "Temp". Is set to "2". Since the initial value of "Length" is set to "1", "Length" becomes "3" in the first while loop.

In the second while loop, "Temp" is "2" and "2" is not "1", so "2" is shifted to the right and multiplied by "1/2" to obtain "Temp". Is set to "1". Since "Length" is currently "3", "Length" becomes "5" in the second while loop. The third while loop is not executed because "Temp" is "1", and f(2) becomes "5".

f(0) is calculated as follows. Since the input coordinate value of f(0) is "0", "0" is shifted to the left by 1 bit, "1" is added, and "Temp" is set to "1". Therefore, the while loop is not executed. F(0) becomes "1" depending on the initial value of "Length".

The predetermined evaluation function “f” described in connection with Expression (3) is a function for estimating the result of entropy coding using variable-length coding. Therefore, the candidate determination unit 920 uses the evaluation function “A” to determine whether or not to exclude “mvx” from the overall candidates for the motion vector predictor by using the evaluation function “A” as a variable length forever. Estimate the encoded result. As a result of the estimation, if there is at least one virtual motion vector difference estimated to be coded to have a length shorter than the actual motion vector difference, “mvx” is excluded from all candidates of the motion vector predictor.

However, it will be easily understood by those skilled in the art to which the present invention belongs that the entropy coding result by another method other than the result of the variable length coding can be estimated. For example, by using another evaluation function “h”, the entropy coding result of the virtual motion vector difference and the entropy coding result of the actual motion vector difference can be estimated and compared, and at this time, “ “H” may be a function that estimates the result of context adaptive binary arithmetic coding.

Further, according to another embodiment of the present invention, in order to improve the accuracy of the evaluation result based on the predetermined evaluation function, the result of evaluating the index information can be estimated together. The index information is information for identifying a predetermined motion vector predictor candidate among all motion vector predictor candidates. This will be described in detail with reference to Equation (4).

A(mvx+MVD-mvy,mvyIdx)<A(MVD,mvxIdx) (4)
The candidate determination unit 920 satisfies “mvy” that satisfies Expression (4) in order to determine whether to exclude “mvx”, which is one of the overall motion vector predictor candidates, from the overall motion vector predictor candidates. , It is determined whether there is at least one in all candidates. In Expression (4), “MVD” means an actual motion vector difference, and mvxIdx and mvyIdx are all candidates of the motion vector predictor, which are index information for specifying “mvx” and “mvy”, respectively. .. In order to determine whether “mvx” is excluded, a virtual motion vector difference “mvx+MVD−” that is a different motion vector predictor candidate “mvy” from the virtual motion vector “mvx+MVD” based on “mvx”. Index information for identifying the index information for identifying “mvy” and “mvy” as overall candidates by using a predetermined evaluation function “A” and identifying the actual motion vector difference and “mvx” as overall candidates Is evaluated using a predetermined evaluation function “A”. As a result of the evaluation, it is determined whether or not there is at least one "mvy" satisfying the mathematical expression (4) in the whole candidates.

As described above, the virtual motion vector difference and the actual motion vector difference evaluated by “A” are defined by the x-coordinate and the y-coordinate, and may also be defined as Equation (5).

A(mvx+MVD-mvy, mvyIdx)=f(p1)+f(q1)+g(mvyIdx)
A(MVD, mvxIdx)=f(p2+f(q2+g(mvxIdx) (5)
Compared with Equation (2), A(mvx+MVD-mvy) on the left side of Equation (2) was evaluated only by the virtual motion vector difference, but A(mvx+MVD-mvy, mvyIdx) in Equation (5) is virtual. And the information for specifying “mvy” in all the candidates of the motion vector predictor are also evaluated. As described above, the evaluation function “A” may be a function for evaluating the entropy-encoded result, and at this time, the function “f” is as described in relation to the mathematical expression (2). The function “g” is a function for estimating the entropy coding result based on the x coordinate value or the y coordinate value of the virtual motion vector difference, and the function “g” is a function for estimating the entropy coding result of “mvxIdx”. May be When the x coordinate value of "mvx+MVD-mvy" is "p1" and the y coordinate value is "q1", A(mvx+MVD-mvy, mvxIdx) should be calculated as shown in Equation (5). You can

A(MVD) on the right side of the equation (2) was also evaluated by the actual motion vector difference, but A(MVD, mvxIdx) of the equation (5) is “mvx” as the actual motion vector difference and the entire candidate motion vector. Together with the information to identify The function “f” is a function for estimating the entropy coding result based on the x-coordinate value or the y-coordinate value of the actual motion vector difference, as described in connection with Expression (2), and the function “g” May be a function for estimating the entropy coding result of “mvxIdx”. When the x-coordinate value of “MVD” is “p2” and the y-coordinate value is “q2”, A(MVD,mvxIdx) can be calculated as shown in Equation (5).

The exclusion judgment according to the formulas (4) and (5) may be used as a supplement to the exclusion judgment according to the formula (2). In other words, it is first determined whether or not “mvx” is excluded from the candidates of the overall motion vector predictor based on the equation (2), and by using the equations (4) and (5), it is possible to exclude the exclusion once more. You can judge. For example, as a result of determination by the mathematical expression (2), “A(mvx+MVD-mvy)” exists only when it is equal to or larger than “A(MVD)”, and “A(mvx+MVD-mvy)” is present. If there is no case smaller than “A(MVD)”, “mvx” is not excluded from the overall candidates for the motion vector predictor according to Expression (2). However, even if “A(mvx+MVD−mvy)” and “A(MVD)” are equal, “mvx” is excluded from all candidates of the motion vector predictor based on the determination results of the formulas (4) and (5). can do.

When the candidate determination unit 920 determines whether to exclude a motion vector predictor candidate based on Equations (1) to (5), iterating for all motion vector predictor candidates according to the C set alignment order. Was explained. According to another embodiment of the present invention, the candidate determination unit 920 may rearrange the C set according to a predetermined criterion and repeat the exclusion determination according to the rearrangement order. This will be described in detail with reference to FIGS. 13A to 13D.

13A to 13D illustrate a position of a current block included in a coding unit having a predetermined size according to an exemplary embodiment of the present invention.

When the candidates of the global motion vector predictor are C={median(mv_a', mv_b', mv_c'), mv_a', mv_b', mv_c', mv_temporal}, binary numbers are added to the motion vector predictor candidates of the C set. It has been explained that, by allocating, the motion vector predictor used to predict the motion vector of the current block may be specified among the motion vector predictor candidates.

At this time, a binary number is assigned according to the alignment order of the motion vector predictor candidates included in the C set, and such a binary number may be a variable length code based on a Huffman code. Therefore, it is possible to allocate a smaller number of bits to the motion vector predictor candidate positioned before in the C set alignment order. For example, in C set, "median(mv_a', mv_b', mv_c')" can be assigned "0" bit, mv_a' can be assigned "00" bit, and mv_b' can be assigned "01" bit. Therefore, the candidate determination unit 920 performs prediction so that the motion vector predictor candidate, which is highly likely to be used for predicting the motion vector of the current block, of the motion vector predictor candidates is positioned in front of the C set. The motion vector candidates are arranged in a predetermined order.

The motion vector predictor, which is likely to be used to predict the motion vector of the current block, is determined by the position of the current block in a coding unit. As shown in FIG. 13A, if the current block is located at the lower end of the coding unit, the motion vector of the current block may be the motion vector of the block adjacent to the left side of the coding unit or the motion vector of the block adjacent to the lower left side of the coding unit. Most likely the same or similar. Therefore, it is necessary to change the alignment order such that the motion vector of the block adjacent to the left side or the motion vector predictor candidate corresponding to the motion vector of the block adjacent to the lower left side is located in front of the C set. Among the candidates of the motion vector predictor of the C set described above, mv_b′ is a candidate of the motion vector predictor corresponding to the motion vector of the block adjacent to the left side, so that the C set includes mv_b′ and median(mv_a′, mv_b′). , Mv_c′) and the order is changed to C={mv_b′, mv_a′, median(mv_a′, mv_b′, mv_c′), mv_c′, mv_temporal}.

Similarly, as shown in FIG. 13B, if the current block is located on the left side of the coding unit, the motion vector of the block adjacent to the left side of the coding unit and the predicted motion corresponding to the motion vector of the block adjacent to the upper part of the coding unit. The vector candidate is likely to be used to predict the motion vector of the current block. Since mv_b′ of the motion vector predictor candidates of the C set described above is a motion vector predictor candidate corresponding to the motion vector of the block adjacent to the left side, the C set includes mv_b′ and median(mv_a′, mv_b′, mv_c′) and the order is changed to C={mv_b′, mv_a′, median(mv_a′, mv_b′, mv_c′), mv_c′, mv_temporal}.

As shown in FIG. 13C, if the current block is located in the upper part of the coding unit, the motion vector of the block adjacent to the left side of the coding unit and the motion vector predictor candidate corresponding to the motion vector of the upper adjacent block are It is likely to be used for the motion vector predictor of the current block. Since mv_a′ of the motion vector predictor candidates of the C set described above is a motion vector predictor candidate corresponding to the motion vector of the block adjacent to the upper part, the C set includes mv_a′ and median(mv_a′, mv_b′, mv_c′) and the order is changed to C={mv_a′, median(mv_a′, mv_b′, mv_c′), mv_b′, mv_c′, mv_temporal}.

As shown in FIG. 13D, if the current block is located on the right side of the coding unit, the motion vector predictor candidate corresponding to the motion vector of the block adjacent to the upper right side of the coding unit predicts the motion vector of the current block. Is likely to be used for. Among the candidates of the motion vector predictor of the C set described above, mv_c′ is a motion vector predictor candidate corresponding to the motion vector of the block adjacent to the upper right side. Therefore, the C set includes mv_c′ and median(mv_a′, mv_b′). , Mv_c′) and the order is changed to C={mv_c′, mv_a′, mv_b′, median(mv_a′, mv_b′, mv_c′), mv_temporal}.

The position of the current block in the coding unit is an example as a criterion for rearranging the motion vector predictor candidates. In other words, various criteria may also be used as criteria for reordering motion vector predictor candidates. Various criteria for aligning a motion vector predictor candidate that is likely to be similar to the motion vector of the current block to the front part of the C set may also be used as a criterion for rearranging the motion vector predictor candidates. A motion vector predictor candidate that is likely to be similar to the motion vector of the current block is determined based on predetermined information related to other blocks encoded before the current block, and the C set is rearranged based on the determination. can do.

In addition, before the motion vector of the current block is coded, a motion vector predictor candidate that is likely to be similar to the motion vector of the current block based on other information coded or decoded for the current block. , And the C set can be reordered based on the determination.

Also, the motion vector predictor candidates that are duplicated when the C set is rearranged can be excluded and realignment can be performed. If all the motion vector predictor candidates have redundant motion vector predictor candidates, the motion vector motion vector candidates are first excluded, and the motion vector predictor candidates are excluded from each of the motion vector predictor candidates by the above-described mathematical expressions (1) to (5). I can judge the situation.

Referring to FIG. 9 again, the motion vector encoding unit 930 encodes the information about the motion vector and the information about the motion vector predictor. The information about the motion vector is a difference vector between the actual motion vector of the current block and the actual motion vector predictor, and the information about the motion vector predictor is at least one of the motion vector predictor's entire candidates. The excluded candidate encodes information for specifying the motion vector predictor used for motion vector prediction of the current block. In other words, the information for specifying the motion vector predictor of the current block among the motion vector predictor candidates that have not been excluded from the candidate determination unit 920 is encoded as the information about the motion vector predictor.

The actual motion vector difference is received from the motion vector estimation unit 910, coded by a predetermined entropy coding method, and the predicted motion determined by the candidate determination unit 920 by selectively excluding at least one predicted motion vector candidate. The information for specifying the motion vector predictor candidate used for predicting the motion vector of the current block determined by the motion vector estimation unit 910 is encoded as a vector candidate.

It is determined if the candidate determination unit 920 determines a motion vector predictor candidate by excluding at least one motion vector predictor candidate from the whole motion vector predictor candidates by the above-described mathematical expressions (1) to (5). The information for identifying the motion vector predictor candidate used to predict the motion vector of the current block among the motion vector predictor candidates is encoded. The motion vector coding unit 930 can index each of the motion vector predictor candidates that have not been excluded from the candidate determination unit 920, and can entropy code the index information as information about the motion vector predictor. Indexing means assigning a predetermined binary number to each motion vector predictor candidate, and the information about the motion vector predictor is used to predict the motion vector of the current block among the motion vector predictor candidates. Means information provided. As a result of the candidate determination unit 920 selectively excluding at least one motion vector predictor candidate, if only one motion vector predictor remains, the motion vector encoding unit 930 separately encodes information about the motion vector predictor. There is no need to convert. This is because the motion vector predictor candidate used for predicting the motion vector of the current block is implicitly determined.

Also, as described with reference to FIGS. 13A to 13D, the candidate determination unit 920 rearranges the candidates of the overall motion vector predictor according to a predetermined criterion, and selects at least 1 from the rearranged candidates of the overall motion vector predictor. It is also possible to index each of the motion vector predictor candidates generated by selectively excluding one motion vector predictor and entropy-encode the index information.

As a result of the rearrangement of the candidate determination unit 920, a binary number having the smallest number of bits is assigned to the motion vector predictor candidate that is likely to be used to predict the motion vector of the current block. The information can be encoded with a higher compression rate.

FIG. 14 illustrates an apparatus for decoding a motion vector according to an embodiment of the present invention.

An apparatus included in the video decoding apparatus 200 of FIG. 2 or the video encoding unit 500 of FIG. 5 and decoding a motion vector is illustrated in detail in FIG. Referring to FIG. 14, a motion vector decoding apparatus 1400 according to an exemplary embodiment of the present invention includes a motion vector decoding unit 1410, a candidate determining unit 1420, and a motion vector restoring unit 1430.

The motion vector decoding apparatus 1400 of FIG. 14 illustrates an apparatus that decodes the motion vector of the current block when the motion vector of the current block is coded in the explicit mode of the explicit mode and the implicit mode. ing.

The motion vector decoding unit 1410 receives the bitstream related to the motion vector of the current block, and decodes the received bitstream. Decode information about motion vectors included in the bitstream. Decode the actual motion vector difference of the current block. The actual motion vector difference can be decoded by a predetermined entropy decoding method. The actual motion vector difference is a difference vector between the motion vector of the current block and the motion vector predictor candidate used to predict the motion vector of the current block.

According to the method of encoding a motion vector of the present invention, at least one motion vector predictor candidate is excluded from all motion vector predictor vector candidates by the above-described mathematical expressions (1) to (5), and the motion vector predictor Candidates are determined. The motion vector predictor candidates are not fixed, but may be continuously changed as the decoding progresses in block units. Therefore, even if the information about the motion vector predictor candidate is the same, if the motion vector predictor candidate is not determined, the motion vector predictor candidate used to predict the motion vector of the current block is accurately restored. Can not do it.

Therefore, prior to determining a motion vector predictor candidate, the candidate determination unit 1420 determines a motion vector predictor candidate. At least one motion vector predictor candidate among all motion vector candidates is selectively excluded by the mathematical formulas (1) to (5) to determine motion vector predictor candidates. Predictive motion that is not used to predict the motion vector of the current block among all candidates determined based on the motion vector of the block included in the previously decoded region adjacent to the current block Vector candidates are excluded based on a predetermined evaluation function.

A virtual motion vector is generated based on information about a predetermined motion vector predictor candidate among all the motion vector predictor candidates and the motion vector decoded by the motion vector decoding unit, and the generated virtual motion vector is generated. A virtual motion vector difference, which is the difference between a motion vector predictor candidate and a vector that is different from the vector, is calculated for each overall candidate. The calculated virtual motion vector difference is compared with the information about the motion vector decoded by the motion vector decoding unit 1410, that is, the actual motion vector difference, and the motion vector predictor candidate is excluded. The entropy coding result of the virtual motion vector difference can be compared with the entropy coding result of the actual motion vector difference to determine whether to exclude a predetermined motion vector predictor candidate. In addition, in order to improve the estimation accuracy of the entropy coding result, the result of entropy coding the index information can also be estimated and used for the exclusion determination. The method of excluding the motion vector predictor candidates has been described with reference to the formulas (1) to (5).

In addition, according to another embodiment of the present invention, the candidate determination unit 1420 rearranges all candidates of the motion vector predictor according to a predetermined criterion, and formulas (1) to ( The exclusion judgment according to 5) can be repeated to selectively exclude at least one motion vector predictor candidate. It is also possible to exclude redundant motion vector predictor candidates from the rearranged overall candidates and repeat the exclusion determination according to equations (1) to (5).

As a result of the candidate determination unit 1420 excluding at least one motion vector predictor candidate from among all motion vector predictor candidates, if there are a plurality of motion vector predictor candidates among all motion vector predictor candidates, motion vector decoding is performed. The unit 1410 decodes the information about the motion vector predictor. Information about the motion vector predictor is decoded by a predetermined entropy decoding method. The information about the motion vector predictor is information for specifying a motion vector predictor candidate used to predict the motion vector of the current block among the motion vector predictor candidates in which at least one motion vector predictor candidate is excluded. Is. Information for identifying the motion vector predictor candidate used to predict the motion vector of the current block among the motion vector predictor candidates that have not been excluded from the candidate determination unit 1420 is decoded.

As a result of the candidate determination unit 1420 excluding at least one motion vector predictor candidate from among all motion vector predictor candidates, if only one motion vector predictor candidate remains, the remaining one motion vector predictor candidate becomes the current block. Since the motion vector decoding unit 1410 is used to predict the motion vector, it is not necessary to separately decode the information about the motion vector predictor candidate.

The motion vector restoration unit 1430 restores the motion vector of the current block based on the information about the motion vector decoded by the motion vector decoding unit 1410. The actual motion vector difference decoded by the motion vector decoding unit 1410 is added to the motion vector predictor candidate used for predicting the motion vector of the current block to restore the motion vector of the current block. Of the motion vector predictor candidates determined by the candidate determination unit 1420, a motion vector predictor candidate to be used for predicting the motion vector of the current block is determined, and the motion vector predictor candidate thus determined is referred to as an actual motion vector difference. to add. As a result of the exclusion by the candidate determination unit 1420, when a plurality of motion vector predictor candidates other than one remain, the motion vector predictor candidate used for predicting the motion vector of the current block is motion vector decoding. It is determined based on the information about the motion vector predictor decoded by the unit 1410.

Since the candidate of the motion vector predictor is determined by the candidate determination unit 1420, even if the information about the decoded motion vector predictor is the same, the motion vector predictor used to predict the motion vector of the current block. The candidates may be motion vectors of blocks adjacent to different positions.

FIG. 15 is a flowchart illustrating a method of encoding a motion vector according to an exemplary embodiment of the present invention. Referring to FIG. 15, in step 1510, the motion vector encoder estimates a motion vector of a current block and selects a motion vector predictor candidate used to predict a motion vector of the current block as a motion vector predictor. Determine from among all candidates. A motion vector that is the same as or similar to the current block is searched for in a plurality of reference pictures, and a motion vector that is a relative position difference between the current block and the reference block is estimated based on the search result.

Then, the motion vector of the current block is predicted based on the motion vector of the block included in the previously encoded area adjacent to the current block. In other words, the motion vector of the block included in the previously coded area adjacent to the current block is set as the overall candidate of the motion vector predictor, and the estimated current block of the overall candidate of the motion vector predictor is set. A motion vector predictor candidate most similar to the motion vector is determined. A difference vector between the motion vector of the current block and the determined motion vector predictor candidate, that is, an actual motion vector difference is generated.

In operation 1520, the video encoder selectively excludes at least one motion vector predictor candidate from all motion vector predictor candidates. Of all the motion vector predictor candidates, motion vector predictor candidates that are not obviously used to predict the motion vector of the current block are excluded.

The video encoding apparatus generates a virtual motion vector by using a predetermined motion vector predictor candidate among all motion vector predictor candidates and the actual motion vector difference generated in step 1510. A virtual motion vector difference is generated by using the generated virtual motion vector and other predicted motion vector candidates. It is possible to generate a virtual motion vector difference for each overall candidate, compare the generated virtual motion vector difference with the actual motion vector difference, and selectively exclude a predetermined motion vector predictor candidate.

It is possible to exclude at least one motion vector predictor candidate from all candidates by repeatedly performing the process of generating the virtual motion vector of step 1520 and the process of selectively excluding it for all candidate candidates. .. When the exclusion process is repeated, a virtual motion vector difference is calculated for each of the remaining motion vector predictor candidates excluding the motion vector motion vector candidates that have already been excluded, and the calculated virtual motion vector difference is calculated. Can be compared to the actual motion vector difference.

The virtual motion vector difference and the actual motion vector difference can be evaluated and compared based on a predetermined evaluation function, and the predetermined evaluation function is a function for predicting the entropy coding result. Comparison can be performed based on a function that estimates the result of entropy coding the virtual motion vector difference and the result of entropy coding the actual motion vector difference. In addition, in order to improve the accuracy of evaluation, the result of entropy coding of the index information can also be estimated and used for the determination of exclusion. The method of excluding at least one motion vector predictor candidate from all motion vector predictor candidates has been described with reference to Formulas (1) to (5).

In addition, the motion vector encoding apparatus may rearrange all motion vector candidates according to a predetermined criterion, as described with reference to FIGS. 13A to 13D, and select at least one motion vector predictor from the rearranged global candidates. Candidates can also be selectively excluded. It is also possible to exclude the redundant motion vector predictor candidates from the rearranged overall candidates and repeat the exclusion determination according to the formulas (1) to (5).

In operation 1530, the motion vector encoder encodes the information about the motion vector and the information about the motion vector predictor. Coding information for identifying the actual motion vector difference and the motion vector predictor candidate used to predict the motion vector of the current block. The information about the motion vector predictor is a motion vector predictor candidate that has not been excluded through steps 1520 and 1530 and is used to identify a motion vector predictor candidate that is used to predict the motion vector of the current block. It may be.

As a result of excluding at least one motion vector predictor candidate from all motion vector predictor candidates, information about the motion vector predictor may not be encoded if only one motion vector predictor candidate remains.

FIG. 16 is a flowchart illustrating a method of decoding a motion vector according to an exemplary embodiment of the present invention. Referring to FIG. 16, in step 1610, the motion vector decoding apparatus decodes information about the motion vector of the current block from the received bitstream. The information about the motion vector may be an actual motion vector difference between the actual motion vector of the current block and the predicted motion vector of the current block.

In step 1620, the motion vector decoding apparatus generates a virtual motion vector based on one motion vector predictor candidate among the motion vector information decoded in step 1610 and all motion vector predictor candidates. ..

When the virtual motion vector is generated, the motion vector decoding apparatus excludes at least one motion vector predictor candidate from all motion vector predictor candidates. An overall candidate for the motion vector predictor is determined based on the motion vector of the block of the previously decoded area adjacent to the current block. The motion vector decoding apparatus can selectively exclude at least one motion vector predictor candidate from all such motion vector predictor candidates. The virtual motion vector difference and the actual motion vector difference decoded in step 1610 are evaluated based on a predetermined evaluation function, and predetermined motion vector predictor candidates are selectively excluded. The method of excluding the motion vector predictor candidate from the overall candidates is the same as in step 1530, and has been described with reference to Equations (1) to (5).

It is possible to exclude at least one motion vector predictor candidate from all candidates by repeatedly performing the process of generating a virtual motion vector of step 1620 and the process of selectively excluding it for all candidate candidates. it can.

In addition, the motion vector encoding apparatus re-aligns all motion vector candidates according to a predetermined criterion, as described with reference to FIGS. 13A to 13D, and selects at least one predicted motion vector Candidates can also be selectively excluded. It is also possible to exclude the redundant motion vector predictor candidates from the rearranged overall candidates and repeat the exclusion determination according to the formulas (1) to (5).

If a result of the exclusion indicates that a plurality of motion vector predictor candidates remain, information about the motion vector predictor is decoded, and if only one motion vector predictor candidate remains, information about the motion vector predictor is not decoded.

In operation 1630, the motion vector decoding apparatus determines a motion vector predictor candidate used to predict the motion vector of the current block among the motion vector predictor candidates not excluded from operation 1620.

Based on the information about the motion vector predictor of the current block, it is possible to determine a motion vector predictor candidate used to predict the motion vector of the current block among the motion vector predictor candidates. When only one motion vector predictor candidate remains as a result of the exclusion in step 1620, the remaining one motion vector predictor candidate is determined as a motion vector predictor candidate used to predict the motion vector of the current block. ..

If the motion vector predictor candidate is determined, the motion vector predictor candidate determined is added to the actual motion vector difference decoded in step 1610 to restore the motion vector of the current block.

As described above, the present invention is not limited to the above-described embodiments even if the present invention is described by the limited embodiments and the drawings, and those skilled in the art to which the present invention belongs If so, various modifications and variations may be possible from such description. Therefore, the idea of the present invention must be understood only by the scope of the claims, and any equivalent or equivalent modifications thereof belong to the scope of the idea of the present invention. Also, the system according to the present invention can be embodied as a computer-readable code on a computer-readable recording medium.

For example, the video coding apparatus, the video decoding apparatus, the motion vector coding apparatus, and the motion vector decoding apparatus according to the exemplary embodiments of the present invention are shown in FIG. 1, FIG. 2, FIG. 4, FIG. 5, FIG. A bus coupled to each unit of the apparatus as illustrated at 14 may be included, at least one processor coupled to the bus. It may also include a memory coupled to the bus for storing instructions, received messages or generated messages and coupled to at least one processor for performing instructions as described above.

In addition, the computer-readable recording medium includes all kinds of recording devices that store data that can be read by a computer system. Examples of the recording medium include a ROM (read-only memory), a RAM (random-access memory), a CD-ROM, a magnetic tape, a floppy (registered trademark) disk, and an optical data storage device. In addition, the computer-readable recording medium may be distributed over computer systems connected to a network, and the computer-readable code may be stored and executed in a distributed manner.

1400 Vector Decoding Device 1410 Motion Vector Decoding Unit 1420 Candidate Determining Unit 1430 Motion Vector Restoring Unit

Claims (10)

In the method of decoding video,
Decoding information about a motion vector difference of a current block in a video and information about a motion vector predictor for specifying a motion vector predictor of the current block from a bitstream;
Constructing a set of motion vector predictor candidates,
Adjusting the motion vector predictor candidate set based on the value of the motion vector predictor candidate in the motion vector predictor candidate set;
Determining a motion vector predictor of the current block based on the adjusted motion vector candidate set and information about the motion vector predictor;
Determining a motion vector of the current block based on information about a motion vector predictor of the current block and a motion vector difference of the current block,
The adjusted motion vector predictor candidate set includes a primary motion vector predictor candidate based on a motion vector of a block adjacent to the current block and a motion vector predictor of a block on a reference picture at the same position as the current block. Including at least one of the following motion vector predictor candidates,
The adjacent blocks include a first block at the upper left of the current block, a second block at the upper right, a third block at the lower left, and a fourth block located above the third block ,
The image is divided into a plurality of maximum coding units according to maximum coding unit size information, and the maximum coding unit is hierarchically divided into one or more coding units having a depth, and a current depth is encoded. units, Ri one der of the divided square units from the coding unit of the upper depth,
The current block is characterized Rukoto included in the coding unit of the current depth, the decoding method. Adjusting the motion vector predictor candidate set includes
When there is a primary motion vector predictor candidate having an overlapping value in the motion vector predictor candidate set, one of the primary motion vector predictor candidates having the overlapping value is removed from the motion vector predictor candidate set. The decoding method according to claim 1, wherein: The adjusted set of motion vector predictor candidates includes a total of two motion vector predictor candidates,
The decoding method according to claim 1, wherein the motion vector predictor information indicates one of the two motion vector predictor candidates through a 1-bit binary value. A decoding unit that decodes information about a motion vector difference of a current block in a video and information about a motion vector predictor for specifying a motion vector predictor of the current block from a bitstream,
A candidate determination unit that configures a motion vector predictor candidate set and adjusts the motion vector predictor candidate set based on the value of the motion vector predictor candidate in the motion vector predictor candidate set;
Based on the information about the adjusted motion vector predictor candidate set and the motion vector predictor, determine the motion vector predictor of the current block, the information about the motion vector difference of the current block and the motion vector difference of the current block. A motion vector restoration unit that determines a motion vector of the current block based on the
The adjusted motion vector predictor candidate set includes a primary motion vector predictor candidate based on a motion vector of a block adjacent to the current block and a motion vector predictor of a block on a reference picture at the same position as the current block. Including at least one of the following motion vector predictor candidates,
The adjacent blocks include a first block at the upper left of the current block, a second block at the upper right, a third block at the lower left, and a fourth block located above the third block ,
The image is divided into a plurality of maximum coding units according to maximum coding unit size information, and the maximum coding unit is hierarchically divided into one or more coding units having a depth, and a current depth is encoded. units, Ri one der of the divided square units from the coding unit of the upper depth,
The current block is characterized Rukoto included in the coding unit of the current depth, the decoding device. The candidate determination unit adjusts the motion vector predictor candidate set, and when there is a primary motion vector predictor candidate having an overlapping value in the motion vector predictor candidate set, a primary motion predictive motion having the overlapping value. The decoding device according to claim 4, wherein one of the vector candidates is removed from the motion vector predictor candidate set. The candidate determination unit adjusts the motion vector predictor candidate set so as to include two motion vector predictor candidates in total,
The decoding device according to claim 4, wherein the candidate determination unit determines one of the two motion vector predictor candidates based on the motion vector predictor information having a 1-bit binary value. In the method of encoding video,
Performing inter prediction on the current block in the image to determine a motion vector of the current block;
Constructing a set of motion vector predictor candidates,
Adjusting the motion vector predictor candidate set based on the value of the motion vector predictor candidate in the motion vector predictor candidate set;
Among the motion vector predictor candidates included in the motion vector predictor candidate set adjusted based on the motion vector of the current block, the motion vector predictor of the current block is determined, and the motion vector predictor of the current block is specified. Encoding information about the motion vector predictor for
Encoding information about a motion vector difference of the current block indicating a difference between the motion vector of the current block and a predicted motion vector of the current block;
Generating a bitstream including information about a motion vector difference of the current block and information about a motion vector predictor for identifying a motion vector predictor of the current block,
The adjusted motion vector predictor candidate set includes a primary motion vector predictor candidate based on a motion vector of a block adjacent to the current block and a motion vector predictor of a block on a reference picture at the same position as the current block. Including at least one of the following motion vector predictor candidates,
The adjacent blocks include upper left, upper right and lower left blocks of the current block,
The image is divided into a plurality of maximum coding units according to a maximum coding unit size, and the maximum coding unit is hierarchically divided into one or more coding units having a depth, and a coding unit of a current depth. Is a square unit divided from a coding unit of upper depth, and is a coding method. In a device that encodes video,
A motion vector estimator for performing inter prediction on the current block in the image to determine the motion vector of the current block;
A candidate determination unit that configures a motion vector predictor candidate set and adjusts the motion vector predictor candidate set based on the value of the motion vector predictor candidate in the motion vector predictor candidate set;
To determine the motion vector predictor of the current block among the motion vector predictor candidates included in the motion vector predictor candidate set adjusted based on the motion vector of the current block, and to specify the motion vector predictor of the current block. Information about the motion vector of the current block is encoded, information about the difference between the motion vector of the current block indicating the difference between the motion vector of the current block and the motion vector predictor of the current block is encoded, and the motion of the current block is encoded. A motion vector encoding unit that generates a bitstream including information about a vector difference and information about a motion vector predictor for specifying a motion vector predictor of the current block;
The adjusted motion vector predictor candidate set includes a primary motion vector predictor candidate based on a motion vector of a block adjacent to the current block and a motion vector predictor of a block on a reference picture at the same position as the current block. Including at least one of the following motion vector predictor candidates,
The adjacent blocks include upper left, upper right and lower left blocks of the current block,
The image is divided into a plurality of maximum coding units according to a maximum coding unit size, and the maximum coding unit is hierarchically divided into one or more coding units having a depth, and a coding unit of a current depth. Is a square unit divided from a coding unit of upper depth, which is a coding unit. In the method of encoding video,
Performing inter prediction on the current block to determine a motion vector of the current block;
Constructing a set of motion vector predictor candidates,
Adjusting the motion vector predictor candidate set based on the value of the motion vector predictor candidate in the motion vector predictor candidate set;
To determine the motion vector predictor of the current block among the motion vector predictor candidates included in the motion vector predictor candidate set adjusted based on the motion vector of the current block, and to specify the motion vector predictor of the current block. Encoding information about the motion vector predictor of
Encoding information about a difference in motion vector of the current block indicating a difference between a motion vector of the current block and a motion vector predictor of the current block;
Generating a bitstream including information about a motion vector difference of the current block and information about a motion vector predictor for identifying a motion vector predictor of the current block,
The adjusted motion vector predictor candidate set includes a primary motion vector predictor candidate based on a motion vector of a block adjacent to the current block and a motion vector predictor of a block on a reference picture at the same position as the current block. Including at least one of the following motion vector predictor candidates,
The encoding method, wherein the adjacent blocks include upper left, upper right and lower left blocks of the current block. In a device that encodes video,
A motion vector estimation unit that performs inter prediction on the current block to determine the motion vector of the current block;
A candidate determination unit that configures a motion vector predictor candidate set and adjusts the motion vector predictor candidate set based on the value of the motion vector predictor candidate in the motion vector predictor candidate set;
To determine the motion vector predictor of the current block among the motion vector predictor candidates included in the motion vector predictor candidate set adjusted based on the motion vector of the current block, and to specify the motion vector predictor of the current block. Information about the motion vector of the current block is encoded, information about the difference between the motion vector of the current block indicating the difference between the motion vector of the current block and the motion vector predictor of the current block is encoded, and the motion of the current block is encoded. A motion vector encoding unit that generates a bitstream including information about a vector difference and information about a motion vector predictor for specifying a motion vector predictor of the current block;
The adjusted motion vector predictor candidate set includes a primary motion vector predictor candidate based on a motion vector of a block adjacent to the current block and a motion vector predictor of a block on a reference picture at the same position as the current block. Including at least one of the following motion vector predictor candidates,
The coding apparatus according to claim 1, wherein the adjacent blocks include upper left, upper right and lower left blocks of the current block.