JP2016154395A - Method and apparatus for encoding/decoding video using motion vector of previous block as motion vector for current block - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and an apparatus for decoding video.SOLUTION: An method and apparatus determines a motion vector of a current block on the basis of a motion vector of at least one block encoded/decoded before the current block, and performs predictive coding/decoding of the current block on the basis of one of predictions among a first direction, a second direction, and bi-directions, by the determined current block.SELECTED DRAWING: Figure 16

Description

  The present invention relates to a method and apparatus for encoding / decoding video, and more particularly, to a method and apparatus for encoding / decoding video based on inter prediction.

  MPEG-1, MPEG-2, MPEG-4 In a video compression method such as H.264 / MPEG-4 AVC (Advanced Video Coding), the video is divided into blocks of a predetermined size in order to encode the video. Next, each block is predictively encoded using inter prediction or intra prediction.

  For inter prediction, search for a block that is the same or similar to the current block using at least one reference frame to estimate the motion, and encode the motion vector generated by the motion estimation result together with the pixel value into the bitstream. To do.

  A technical problem to be solved by the present invention is to determine a motion vector of a current block based on a motion vector of at least one previous block, and to encode / decode a video based on the determined motion vector. And a computer-readable recording medium on which a program for performing the method is recorded.

  According to an embodiment of the present invention for solving the technical problem, a motion vector of a current block is determined based on a motion vector of at least one block decoded before the current block, and the determined motion vector is The method of decoding the current block using the first direction, second direction, and bidirectional decoding information about a prediction direction used for decoding the current block and information about a pixel value of the current block Determining a prediction direction of the current block based on information about the decoded prediction direction, and determining at least one motion vector for performing prediction of the determined prediction direction; Based on at least one motion vector for prediction in a predetermined prediction direction and the decoded pixel value information Restoring the current block, wherein the first direction is a direction from the current picture to a preceding picture, and the second direction is a direction from the current picture to a subsequent picture. And

  According to an embodiment of the present invention for solving the technical problem, a motion vector of a current block is determined based on a motion vector of at least one block encoded before the current block, and the determined motion vector is The method of encoding a current block using the method includes: determining a motion vector in a first direction and a motion vector in a second direction of the current block based on a motion vector of at least one block encoded before the current block. A prediction used for encoding the current block among the prediction in the first direction, the prediction in the second direction, and the bidirectional prediction based on the motion vector in the first direction and the motion vector in the second direction; Determining; information about the prediction direction, and a pixel of the current block generated based on the determined prediction. Encoding information about values, wherein the first direction is a direction from the current picture to a preceding picture, and the second direction is a direction from the current picture to a succeeding picture. It is characterized by.

  According to an embodiment of the present invention for solving the technical problem, a motion vector of a current block is determined based on a motion vector of at least one block decoded before the current block, and the determined motion vector is The apparatus for decoding the current block using the information decodes information about a prediction direction used for decoding the current block among the first direction, the second direction, and bidirectional, and information about a pixel value of the current block. A decoding unit configured to determine a prediction direction of the current block based on the information about the decoded prediction direction, and at least one motion vector determination unit for performing prediction of the determined prediction direction; Based on at least one motion vector for prediction in the defined prediction direction and the decoded pixel value information A restoration unit that restores a current block, wherein the first direction is a direction from the current picture to a preceding picture, and the second direction is a direction from the current picture to a subsequent picture. And

  According to an embodiment of the present invention for solving the technical problem, a motion vector of a current block is determined based on a motion vector of at least one block encoded before the current block, and the determined motion vector is The apparatus for encoding a current block using the motion determining a motion vector in a first direction and a motion vector in a second direction of the current block based on a motion vector of at least one block encoded before the current block. Vector determining unit; used for encoding the current block among the prediction in the first direction, the prediction in the second direction, and the bidirectional prediction based on the motion vector in the first direction and the motion vector in the second direction Define a prediction, information about the prediction direction, and the current block generated based on the determined prediction An encoding unit that encodes information about a csel value, wherein the first direction is a direction from the current picture to a preceding picture, and the second direction is from the current picture to the succeeding picture. It is a direction.

  In order to solve the technical problem, the present invention provides a computer-readable recording medium for performing the video encoding method and / or video decoding method.

  According to the present invention, the probability of occurrence of a coding mode for coding using the motion vector of at least one previous block as the motion vector of the current block is increased, the prediction accuracy is increased, and the compression rate is further increased. Video can be encoded / decoded.

1 is a diagram illustrating a video encoding apparatus according to an embodiment of the present invention. 1 is a diagram illustrating a video decoding apparatus according to an embodiment of the present invention. 2 is a diagram illustrating a hierarchical coding unit according to an embodiment of the present invention. 3 is a diagram illustrating a video encoding unit based on a coding unit according to an exemplary embodiment of the present invention. 3 is a diagram illustrating a video decoding unit based on a coding unit according to an exemplary embodiment of the present invention. 3 is a diagram illustrating a maximum coding unit, a sub-coding unit, and a prediction unit according to an embodiment of the present invention. 3 is a diagram illustrating a coding unit and a conversion unit according to an exemplary embodiment of the present invention. 3 is a diagram illustrating a division form of a coding unit, a prediction unit, and a frequency conversion unit according to an embodiment of the present invention. 3 is a diagram illustrating a division form of a coding unit, a prediction unit, and a frequency conversion unit according to an embodiment of the present invention. 6 is a diagram illustrating a video encoding apparatus according to another exemplary embodiment of the present invention. 3 is a diagram illustrating a method for predicting a block included in a bidirectional prediction picture according to an exemplary embodiment of the present invention. 6 is a diagram illustrating a method for determining a motion vector of a current block based on a motion vector of a previously encoded block according to an exemplary embodiment of the present invention. 6 is a diagram illustrating a method for determining a motion vector of a current block based on a motion vector of a previously encoded block according to an exemplary embodiment of the present invention. 6 is a diagram illustrating a method for determining a motion vector of a current block based on a motion vector of a previously encoded block according to another exemplary embodiment of the present invention. 6 is a diagram illustrating a method for determining a motion vector of a current block based on a motion vector of a previously encoded block according to another exemplary embodiment of the present invention. 6 is a diagram illustrating a method for determining a motion vector of a current block based on a motion vector of a previously encoded block according to another exemplary embodiment of the present invention. 6 is a diagram illustrating a method for determining a motion vector of a current block based on a motion vector of a previously encoded block according to another exemplary embodiment of the present invention. 6 is a diagram illustrating a video decoding apparatus according to another embodiment of the present invention. 5 is a flowchart for explaining a video encoding method according to an exemplary embodiment of the present invention. 5 is a flowchart for explaining a video decoding method according to an embodiment of the present invention;

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a diagram illustrating a video encoding apparatus according to an embodiment of the present invention. Referring to FIG. 1, a video encoding apparatus 100 according to an embodiment of the present invention includes a maximum encoding unit division unit 110, an encoding depth determination unit 120, a video data encoding unit 130, and an encoding information encoding unit 140. Is provided.

  The maximum coding unit dividing unit 110 can divide a current frame or a current slice based on a maximum coding unit that is a coding unit of the maximum size. The current frame or current slice can be divided by at least one maximum coding unit.

  According to an embodiment of the present invention, a coding unit is represented using a maximum coding unit and a depth. As described above, the maximum coding unit indicates a coding unit having the largest size among the coding units of the current frame, and the depth indicates a degree to which the coding unit is hierarchically reduced. As the depth increases, the coding unit shrinks from the largest coding unit to the smallest coding unit, the depth of the largest coding unit is defined as the minimum depth, and the depth of the smallest coding unit is defined as the maximum depth. Is done. Since the maximum coding unit decreases in size as the depth increases, the sub-coding unit of k depth includes a plurality of sub-coding units having a depth larger than k.

  If the video is encoded in a larger unit as the size of the frame to be encoded increases, the video can be encoded at a higher video compression rate. However, if the encoding unit is increased and the size is fixed, the video cannot be encoded efficiently reflecting the characteristics of the video that keeps changing.

  For example, when encoding a flat area such as the sea or the sky, the compression rate improves as the encoding unit is increased. However, when encoding a complicated area such as a person or a building, the encoding unit is decreased. The compression rate is improved as the value increases.

  To this end, according to an embodiment of the present invention, a maximum video coding unit having a different size is set for each frame or slice, and a maximum depth is set. Since the maximum depth means the maximum number of times that the encoding unit can be reduced, the minimum encoding unit size included in the maximum video encoding 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 an RD cost (Rate-Distortion Cost) calculation. The maximum depth is determined differently for each frame or slice, or is determined differently for each maximum coding unit. The determined maximum depth is output to the encoding information encoding unit 140, and the video data by maximum encoding unit is output to the video data encoding unit 130.

  The maximum depth means the smallest size coding unit that can be included in the maximum coding unit, that is, the smallest coding unit. In other words, the maximum coding unit is divided into sub-coding units of different sizes according to different depths. This will be described in detail later with reference to FIGS. 8A and 8B. Further, 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 is to transform a spatial domain pixel value into a frequency domain coefficient, and is a discrete cosine transformation or KLT (Karhunen Loever Transform).

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

  For example, the video encoding apparatus 100 selects a processing unit different from the encoding unit in order to predict a predetermined encoding unit.

  When the size of the coding unit is 2N × 2N (where N is a positive integer), the processing units for prediction are 2N × 2N, 2N × N, N × 2N, N × N, and the like. In other words, motion prediction may be performed based on a processing unit that halves at least one of the height or width of the coding unit. Hereinafter, the processing unit that is the basis of the prediction is referred to as '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 is performed only for a prediction unit of a specific size or form. For example, the intra mode is performed only on a 2N × 2N, N × N prediction unit that is a square. Further, the skip mode is performed only for the prediction unit of 2N × 2N size. If there are a plurality of prediction units within the coding unit, prediction is performed for each prediction unit, and the prediction mode with the smallest coding error is selected.

  The video encoding apparatus 100 can convert video data based on a processing unit having a size different from the encoding unit. For the conversion of the coding unit, the conversion is performed based on a data unit that is smaller than the coding unit or has the same size. Hereinafter, a processing unit that is the basis of conversion is referred to as a “conversion unit”.

  The coding depth determination unit 120 may determine a sub-coding unit included in the maximum coding unit using a Lagrange multiplier-based rate-distortion optimization technique. In other words, it is determined in what form the plurality of sub-coding units are divided into the maximum coding unit. Here, the plurality of sub-coding units have different sizes depending on the depth. Next, the video data encoding unit 130 encodes the maximum encoding unit based on the division form determined by the encoding depth determination unit 120 and outputs a bitstream.

  The encoding information encoding unit 140 encodes information about the encoding mode of the maximum encoding unit determined by the encoding 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 by depth are encoded, and a bit stream is output. The information about the coding mode of the sub-coding unit includes 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 about the division form of the maximum coding unit is information indicating how to divide each coding unit. For example, when encoding by dividing the maximum coding unit, information indicating whether the maximum coding unit is divided is encoded, and the sub-coding unit generated by dividing the maximum coding unit is divided again. Even when encoding is performed, information indicating whether each sub-coding unit is divided is encoded. The information indicating the division may be flag information indicating the division.

  There are sub-coding units of different sizes for each maximum coding unit, and information about the coding mode must be determined for each sub-coding unit. Therefore, at least one sub-coding unit is required for one maximum coding unit. Information about one coding mode is defined.

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

  Therefore, the video encoding apparatus 100 according to an embodiment can determine an optimal division form for each maximum coding unit based on the size and the maximum depth of the maximum coding unit in consideration of video characteristics. By adjusting the size of the maximum coding unit variably in consideration of the video characteristics, and dividing the maximum coding unit by sub-coding units of different depths, the video is encoded, thereby enabling the video of various resolutions to be encoded. It can be encoded more efficiently.

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

  The video related data acquisition unit 210 parses the bitstream 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 video data acquisition unit 210 extracts information on the maximum coding unit of the current frame or slice from the header for the current frame or slice. In other words, the bit stream is divided by the maximum coding unit, and the video data decoding unit 230 decodes the video data for each maximum coding unit.

  The encoding information extraction unit 220 parses the bit sequence received by the video decoding apparatus 200, and from the header for the current frame, the maximum encoding unit, the maximum depth, the division form of the maximum encoding unit, the code of the sub encoding unit Information about the conversion mode. Information regarding the division form and the encoding mode is output to the video data decoding unit 230.

  The information on the division form of the maximum coding unit includes information on sub-coding units having different sizes depending on the depth included in the maximum coding unit. As described above, the information on the division form may be information (for example, flag information) indicating whether or not the division is performed with respect to each coding unit. The information related to the coding mode includes information about the prediction unit for each sub-coding unit, information about the prediction mode, information about the transform unit, and the like.

  Based on the information extracted by the encoding information extraction unit, the video data decoding unit 230 decodes the video data of each maximum encoding unit and restores the current frame.

  Based on the information about the division format of the maximum coding unit, the video data decoding unit 230 decodes the sub-coding unit included in the maximum coding unit. The decoding process includes an inter prediction process including intra prediction and motion compensation, and an inverse conversion process.

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

  FIG. 3 is a diagram illustrating 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 includes 32 × 32, 16 × 16, 8 × 8, 4 × 4 from coding units having a width × height of 64 × 64. In addition to the square encoding unit, the encoding unit has a width × height of 64 × 32, 32 × 64, 32 × 16, 16 × 32, 16 × 8, 8 × 16, 8 × 4, 4 × 8 Exists.

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

  Furthermore, for 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 video data 330 having a resolution of 352 × 288, the size of the maximum coding unit is set to 16 × 16 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 the compression rate improvement. Accordingly, the video data 310 and 320 having higher resolution than the video data 330 is selected to have a maximum encoding unit size of 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 is a sub-code whose major axis size is 32 or 16 as the depth increases from the largest coding unit whose major axis size is 64. Includes up to unit.

  On the other hand, since the maximum depth of the video data 330 is 2, the encoding unit 335 of the video data 330 has a long axis size of 8 or 4 as the depth increases from the maximum encoding unit whose long axis size is 16. Includes up to coding units.

  Since the maximum depth of the video data 320 is 4, the coding unit 325 of the video data 320 has a major axis size of 32, 16, 8, 4 as the depth increases from the largest coding unit having a major axis size of 64. Up to sub-coding units. Since the video is encoded on the basis of a smaller sub-encoding unit as the depth increases, it is suitable for encoding an image including a more detailed scene.

  FIG. 4 illustrates a video encoding unit based on a coding unit according to an embodiment of the present invention. The intra prediction unit 410 performs intra prediction on the intra mode prediction unit in the current frame 405, and the motion estimation unit 420 and the motion compensation unit 425 perform the current frame 405 and the reference frame on the inter mode prediction unit. 495 is used to perform inter prediction and motion compensation.

  Residual values are generated based on the prediction units output from the intra prediction unit 410, the motion estimation unit 420, and the motion compensation unit 425, and the generated residual values are quantized through the transform unit 430 and the quantization unit 440. Is output to the converted conversion factor.

  The quantized transform coefficient is restored to the residual value again through the inverse quantization unit 460 and the inverse transform unit 470, and the restored residual value is post-processed through the deblocking unit 480 and the loop filtering unit 490. Are output to the reference frame 495. The quantized transform coefficient is output to the bit stream 455 through the entropy encoding unit 450.

  In order to perform encoding using the video encoding method according to an exemplary embodiment of the present invention, 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. 440, entropy coding unit 450, inverse quantization unit 460, inverse transform unit 470, deblocking unit 480, and loop filtering unit 490 are all in the maximum coding unit, sub-coding unit by depth, prediction unit, and transform unit. Based on this, the video encoding process is processed.

  FIG. 5 is a diagram illustrating 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 encoded video data to be decoded and the encoding information necessary for decoding are parsed. The encoded video data is output to the inversely quantized data through the entropy decoding unit 520 and the inverse quantization unit 530, and restored to the residual value through the inverse transform unit 540. The residual value is added to the result of intra prediction by the intra prediction unit 550 or the result of motion compensation from the motion compensation unit 560, and is restored for each coding unit. The restored coding unit is used for prediction of the next coding unit or the next frame through the deblocking unit 570 and the loop filtering unit 580.

  In order to perform decoding by a video decoding method according to an embodiment of the present invention, a parsing unit 510, an entropy decoding unit 520, an inverse quantization unit 530, an inverse transform unit 540, an intra unit, which are components of the video decoding unit 400, The prediction unit 550, the motion compensation unit 560, the deblocking unit 570, and the loop filtering unit 580 each process the video decoding process based on the maximum coding unit, the sub-coding unit based on the depth, 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 considers the size of the transform unit. Reverse conversion.

  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 embodiment of the present invention use hierarchical encoding units to perform encoding / decoding in consideration of video characteristics. The maximum coding unit and the maximum depth may be adaptively set according to video characteristics or variously set according to user needs.

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

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

  Referring to FIG. 6, an example of a prediction unit is 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 size 64 × 64 coding unit 610, the size 64 × 64 prediction unit 610, and the size 64 × 32 prediction unit 612. , A prediction unit 614 having a size of 32 × 64 and a prediction unit 616 having a size of 32 × 32.

  The prediction unit of the coding unit 620 with the depth 32 and the size 32 × 32 is the same as or smaller than the coding unit 620 with the size 32 × 32, and the prediction unit 620 with the size 32 × 32 and the prediction with the size 32 × 16. A unit 622, a prediction unit 624 of size 16 × 32, and a prediction unit 626 of size 16 × 16.

  The prediction unit of the coding unit 630 of the size 16 × 16 of the depth 2 is the same as or smaller than the coding unit 630 of the size 16 × 16, and the prediction unit 630 of the size 16 × 16 and the prediction of the size 16 × 8. A unit 632, a prediction unit 634 having a size of 8 × 16, and a prediction unit 636 having a size of 8 × 8.

  The prediction unit of the size 8 × 8 coding unit 640 at the depth 3 is the same as or smaller than the size 8 × 8 coding unit 640, the size 8 × 8 prediction unit 640, and the size 8 × 4 prediction. A unit 642, a prediction unit 644 of size 4 × 8, and a prediction unit 646 of size 4 × 4.

  Finally, the depth 4 size 4 × 4 coding unit 650 is the maximum depth coding unit, and the prediction unit is the size 4 × 4 prediction unit 650. However, even if the coding unit has the maximum depth, the size of the coding unit and the prediction unit do not necessarily have to be the same. Like the other coding units 610 to 650, the prediction of a size smaller than the coding unit is required. The prediction may be performed by dividing into units.

  FIG. 7 is a diagram illustrating a coding unit and a conversion unit according to an embodiment of the present invention. The video encoding apparatus 100 and the video decoding apparatus 200 according to an embodiment of the present invention may encode the maximum coding unit as it is, or may be smaller than the maximum coding unit, or may be the maximum sub-coding unit. Are divided and encoded. During the encoding process, the size of the transform unit for transform is also selected as the size for the highest compression rate regardless of the encoding unit and the prediction unit. For example, when the current encoding unit 710 is 64 × 64 size, conversion may be performed using a 32 × 32 size conversion unit 720.

  FIG. 8A and FIG. 8B are diagrams illustrating division forms of a coding unit, a prediction unit, and a transform unit according to an embodiment of the present invention.

  FIG. 8A illustrates a coding unit and a prediction unit according to an embodiment of the present invention. The left side of FIG. 8A illustrates a division form selected by the video encoding apparatus 100 according to an embodiment of the present invention to encode the maximum coding unit 810. The video encoding apparatus 100 divides and encodes the maximum encoding unit 810 into various forms, compares the encoding results of various divided forms based on the RD cost, and selects an optimal division form. To do. When it is optimal to encode the maximum encoding unit 810 as it is, the maximum encoding unit 800 may be encoded without dividing the maximum encoding unit 810 as shown in FIGS. 8A and 8B.

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

  Of the sub-coding units of depth 1, the sub-coding unit positioned at the upper right side and the sub-coding unit positioned at the lower left side are divided into sub-coding units of depth 2 or more. Some of the sub-coding units having a depth of 2 or more are again divided into sub-coding units having a depth of 3 or more.

  The right side of FIG. 8B illustrates the division form of the prediction unit for the maximum coding unit 810.

  Referring to the right side of FIG. 8A, the prediction unit 860 for 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 for the sub-coding unit 854 located at the lower right side among the sub-coding units of depth 1 is smaller than the sub-coding unit 854. Of the sub-coding units 814, 816, 818, 828, 850, and 852 of depth 2, the prediction units for some sub-coding units 815, 816, 850, and 852 are smaller than the sub-coding units.

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

  FIG. 8B is a diagram illustrating a prediction unit and a conversion unit according to an embodiment of the present invention. The left side of FIG. 8B illustrates a partition form of the prediction unit for the maximum coding unit 810 illustrated on the right side of FIG. 8A, and the right side of FIG. 8B illustrates a partition form of the transform unit of the maximum coding unit 810.

  Referring to the right side of FIG. 8B, the division form of the conversion unit 870 is set differently from the prediction unit 860.

  For example, even if the prediction unit for the coding unit 854 with depth 1 is selected to have a half height, the transform unit may be selected to have the same size as the coding unit 854 with depth 1. Similarly, even if the prediction unit for the depth 2 coding units 814 and 850 is selected to be half the height of the depth 2 coding units 814 and 850, the transform unit is the depth 2 coding unit. The same size as the original size of 814, 850 can be selected.

  The conversion unit may be selected to have a size smaller than the prediction unit. For example, when the prediction unit for the coding unit 852 at the depth 2 is selected to have a half width, the transform unit is selected to have a half height and width that are smaller than the prediction unit. Is done.

  FIG. 9 illustrates a video encoding apparatus according to another embodiment of the present invention. A video encoding device 900 of FIG. 9 is a device that is provided in the video encoding device 100 of FIG. 1 and the video encoding device 400 of FIG. 4 and encodes the current block based on inter prediction.

  Referring to FIG. 9, the video encoding apparatus 900 includes a motion vector determination unit 910 and an encoding unit 920.

  In the partial encoding mode, a motion vector of the current block is determined based on a motion vector of at least one block encoded before the current block, and the current block is encoded based on the determined motion vector. The direct prediction mode and the skip mode are examples of such a mode. Both the direct prediction mode and the skip mode are encoding modes in which the motion vector of the current block is determined based on previously encoded information, and thus the motion vector is not separately encoded as information about the current block.

  However, in the direct prediction mode, the residual block generated by subtracting the prediction block generated by the motion vector from the current block is encoded as information about the pixel value, whereas in the skip mode, the prediction block is The difference is that only the flag information indicating that it is encoded in the skip mode is encoded as information about the pixel value, assuming that it is the same as the current block.

  Although both the direct prediction mode and the skip mode are encoding based on inter prediction, a motion vector is not separately encoded, and thus greatly improves the compression ratio. However, since the direct prediction mode and the skip mode encode only the current block by performing prediction in a specific prediction direction, there are disadvantages in that the occurrence probability is low and the prediction is likely to be inaccurate. Accordingly, the image encoding apparatus 900 according to an embodiment of the present invention predicts and encodes in various prediction directions when encoding the current block included in the bi-predictive picture in the direct prediction mode or the skip mode. A detailed description will be given below with reference to the drawings.

  FIG. 10 is a diagram illustrating a method for predicting a block included in a bidirectional prediction picture according to an embodiment of the present invention. Referring to FIG. 10, when the current block 1010 included in the current picture 1000 which is a bi-predictive picture is encoded, the current block includes a picture 1020 at a time before the current picture and a picture 1030 at a time after the current picture. Predictive coding is performed with reference to at least one of them. At least one block 1022 and 1032 corresponding to the current block 1010 is searched from at least one of the previous time picture 1020 and the subsequent time picture 1030, and the current block is predictively encoded based on the searched block.

  In other words, when the direction from the current picture 1000 to the previous picture 1020 is the first direction (ie, the L0 direction), the current block 1010 is predicted based on the corresponding block 1022 searched for the picture in the first direction ( Hereinafter, it is referred to as “first direction prediction”). Similarly, when the direction from the current picture 1000 to the picture 1030 is referred to as the second direction (ie, the L1 direction), the current block 1010 is predicted based on the corresponding block 1032 searched for the picture in the second direction ( Hereinafter, it is referred to as “second direction prediction”). The current block 1010 may be predicted based on both the first direction prediction and the second direction prediction, that is, bidirectional prediction.

  However, the direct prediction mode according to the conventional technique is applied only when bi-directional prediction is performed on the current block 1010. In other words, when only the first direction prediction is performed and the current block is predictively encoded, the direct prediction mode cannot be encoded, and only the second direction prediction is performed and the current block is predictively encoded. Cannot be encoded by the direct prediction mode. The same applies to the skip mode according to the prior art. According to the skip mode according to the prior art, the motion vector of the current block 1010 defined by the motion vector of the previously encoded block adjacent to the current block 1010 is not a motion vector mv_L0 in the first direction. Instead, the prediction block generated based on the first direction prediction is regarded as the same as the current block 1010, and flag information indicating that the encoding is performed in the skip mode is encoded.

  In short, according to the prior art, the predictions that can be performed on the blocks included in the bi-predictive picture are the first directional prediction, the second directional prediction, and the bi-directional prediction. Since the skip mode is applied only when prediction is performed in a specific direction, there is a disadvantage in that the direct prediction mode and the skip mode that have a large effect on the compression rate are limitedly applied.

  In order to solve this disadvantage, the video encoding apparatus 900 according to the present invention determines the motion vector of the current block 1010 based on previously encoded information, and does not encode the motion vector, so that the prediction is performed. Encoding is performed by a video encoding method that can be performed in all directions.

  The motion vector determination unit 910 determines the first direction motion vector and the second direction motion vector of the current block 1010 in order to perform the first direction prediction, the second direction prediction, and the bidirectional prediction. The first direction motion vector and the second direction motion vector are determined based on the motion vector of at least one block encoded before the current block.

  The first direction motion vector and the second direction motion vector are determined by a motion vector determination method according to the prior art. For example, when the current block 1010 is encoded in the direct prediction mode, that is, in the mode in which only the information about the residual block is encoded without encoding the information about the motion vector, the H. The motion vector can be determined by the method of determining the motion vector in the H.264 / AVC direct prediction mode. When the current block 1010 is encoded in a skip mode, that is, a mode in which neither information about motion vectors nor information about residual blocks is encoded. The motion vector can be determined by the method of determining the motion vector in the H.264 / AVC skip mode.

  H. The H.264 / AVC direct prediction mode includes a temporal direct prediction mode and a spatial direct prediction mode. Therefore, H.H. H.264 / AVC temporal direct prediction mode for determining the motion vector of the current block and spatial direct prediction mode for determining the current block motion vector, the motion vector determining unit 910 uses the first direction motion vector and the second direction motion vector. Used to define a vector. This will be described in detail with reference to FIGS. 11A and 11B.

  FIG. 11A illustrates a method for determining a motion vector of a current block based on a motion vector of a previously encoded block according to an embodiment of the present invention. Referring to FIG. 11A, when the current block 1010 is encoded in the temporal direct prediction mode, the motion vector of the current block 1010 of the current picture 1110 is the same as that of the block 1120 at the same position of the picture 1114 that is temporally following. Generated using motion vectors.

  In other words, when the picture 1114 that follows temporally is called an anchor picture, the anchor picture 1114 is based on the motion vector of the block 1120 at the same position of the current block, and the first direction motion vector and the second direction motion of the current block. A vector can be defined. The motion vector of block 1120 at the same position is determined based on the temporal distance between the current picture 1110 and the preceding picture 1112 and the temporal distance between the anchor picture 1114 and the preceding picture 1112. , And the first direction motion vector and the second direction motion vector of the current block 1010 are determined.

  For example, if the motion vector mv_colA of the block 1120 at the same position as the current block 1010 is generated for the retrieved block 1122 of the picture 1112 before the current picture 1010, the first direction motion vector of the current block 1110 and the first motion vector The two-direction motion vectors mv_L0A and mv_L1A are generated as follows.

mv_L0A = (t1 / t2) * mv_colA
mv_L1A = mv_L0A-mv_colA
Here, mv_L0A means the first direction motion vector of the current block 1010, and mv_L1A means the second direction motion vector of the current block 1010.

  FIG. 11B illustrates a method for determining a motion vector of a current block based on a motion vector of a previously encoded block according to an embodiment of the present invention. Referring to FIG. 11B, the first direction motion vector and the second direction motion vector of the current block 1010 are determined based on the motion vectors mv_A, mv_B, and mv_C of the blocks 1130 to 1134 adjacent to the current block 1100. It is done. A first direction motion vector and a second direction motion vector are determined based on the motion vectors of the blocks currently located at the upper left portion and the upper right portion of the block 1010.

  When encoding the current block in the spatial direct prediction mode, the median value of the motion vector in the first direction among mv_A, mv_B, and mv_C is determined as the first direction motion vector of the current block 1010, and mv_A, mv_B, and mv_C. The median value of the motion vector in the second direction is determined as the second direction motion vector of the current block 1010. When determining the first direction motion vector, the motion vector in the second direction among mv_A, mv_B and mv_C is set to '0' to calculate the median value. When determining the second direction motion vector, mv_A, mv_B and The motion vector in the first direction in mv_C is set to “0” and the median value is calculated.

  The picture corresponding to the smallest number among the first direction reference numbers by mv_A, mv_B and mv_C is defined as the first direction reference picture, and the picture corresponding to the smallest number among the second direction reference numbers by mv_A, mv_B and mv_C. Is defined as the second direction reference picture.

  When encoding the current block 1010 in the skip mode, as shown in FIG. 11B, the first direction motion vector of the motion vectors mv_A, mv_B, and mv_C of the blocks 1130 to 1134 adjacent to the current block 1010 is used. The median is defined as the motion vector for the current block.

  If the video encoding apparatus 900 determines a motion vector according to FIGS. 11A and 11B and encodes the current block, on the decoding side, the motion vector of the current block is determined using the same method as in FIGS. 11A and 11B. Restore. In other words, the video encoding side and the decoding side implicitly share the same motion vector determination method, and the motion vector of the current block can be determined by the shared motion vector determination method.

  However, according to still another embodiment of the present invention, the encoding side generates a plurality of motion vector candidates based on the motion vectors of a plurality of blocks encoded before the current block, Information for specifying the motion vector of the current block in the motion vector candidate is explicitly encoded and inserted into the beast stream, and the decoding side is based on the information that has been explicitly encoded and inserted. The motion vector of the block can be determined.

  Hereinafter, this will be described in detail with reference to FIGS. 12A and 12B. 12A and 12B illustrate a method for determining a motion vector of a current block based on a motion vector of a previously encoded block according to still another embodiment of the present invention.

  Referring to FIG. 12A, the motion vector determination unit 910 generates a plurality of motion vector candidates based on a motion vector of a previously encoded block adjacent to the current block. Of the blocks adjacent to the upper part of the current block, the leftmost a0 block, the uppermost b0 block adjacent to the left side, the c block adjacent to the upper right side, the d block adjacent to the upper left side, and The motion vector of the e block adjacent to the lower right side is a plurality of motion vector candidates.

  Among the motion vectors of the a0 block, b0 block, c block, and d block, one of the motion vectors in the first direction is determined as the motion vector in the first direction of the current block, and the a0 block, the b0 block, the c block, and d. One of the motion vectors in the second direction among the motion vectors of the block is determined as the motion vector in the second direction of the current block. For example, if the motion vectors of the a0 block and the b0 block among the motion vectors of the a0 block, the b0 block, the c block, and the d block are motion vectors in the first direction, the motion vector of the a0 block and the motion vector of the b0 block One is defined as the first direction motion vector of the current block, and one of the remaining c block and d block motion vectors is defined as the second direction motion vector of the current block.

  There is no limitation on a method for determining one of a plurality of motion vector candidates as a motion vector of the current block, but in general, a motion vector that can predict the current block more accurately can be selected. In the above-described example, if the current block is predicted more accurately when prediction is performed using the motion vector of the a0 block out of the motion vector of the a0 block and the motion vector of the b0 block which are motion vectors in the first direction. , The motion vector of the a0 block is defined as the first direction motion vector of the current block. The SAD (sum of absolute difference) of the residual block generated by subtracting the prediction block generated by the prediction result of each motion vector from the current block is calculated, and the small motion vector of the SAD is calculated as the motion of the current block. It is defined as a vector.

  Referring to FIG. 12B, motion vectors of all blocks adjacent to the current block are used as motion vector candidates. 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 are used as motion vector candidates, and the bulllock dollars adjacent to the left side are used. Among them, not only the uppermost b0 block but also the motion vectors of all the blocks adjacent on the left side are used as motion vector candidates.

  As described above with reference to FIG. 12A, among the motion vector candidates of all blocks, one of the motion vectors in the first direction is defined as the first direction motion vector of the current block, and one of the motion vectors in the second direction is the current motion vector. It is defined as the second direction motion vector of the block.

  In summary, according to FIGS. 11A and 11B, and FIGS. 12A and 12B, the motion vector determination unit 910 determines one of the following motion vector candidates as the motion vector of the current block.

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_L0A, mv_L1A}
mv_L0A and mv_L1A are motion vectors according to FIG. 11A, and median (mv_a0, mv_b0, mv_c) is a motion vector according to FIG. 11B. The remaining motion vectors were described above with respect to FIGS. 12A and 12B.

  Among the motion vectors in the first direction included in the C set, the first direction motion vector of the current block is determined, and among the motion vectors in the second direction included in the C set, the second direction motion vector of the current block is determined. It is done.

  In addition, according to another embodiment of the present invention, the number of candidates may be reduced, and the motion vector of the current block may be determined.

C = {median (mv_a ′, mv_b ′, mv_c ′), mv_a ′, mv_b ′, mv_c ′, mv_L0A, mv_L1A}
Here, mv_x means a motion vector of the x block, median () means a median value, and mv_a ′ means a valid first motion vector among mv_a0, mv_a1,..., Mv_aN. For example, when the a0 block is encoded using intra prediction, the motion vector mv_a0 of a0 is not valid, so mv_a ′ = mv_a1, and when the motion vector of the a1 block is not valid, mv_a ′ = mv_a2.

  Similarly, mv_b ′ means a valid first motion vector among mv_b0, mv_b1,..., Mv_bN, and mv_c ′ means a valid first motion vector among mv_c, mv_d, and mv_e.

  mv_L0A and mv_L1A are motion vectors according to FIG. 11A. Further, according to another embodiment of the present invention, instead of mv_L0A and mvL1A, another motion vector generated using a time distance between adjacent pictures is included in the candidates. This will be described in detail with reference to FIGS. 13A and 13B.

  13A and 13B illustrate a method for determining a motion vector of a current block based on a motion vector of a previously encoded block according to still another embodiment of the present invention.

  Referring to FIG. 13A, a motion vector candidate determined based on a temporal distance is determined by a method different from the temporal direct prediction mode according to the prior art.

  The motion vector candidate of the current block 1010 of the current picture 1110 is generated using the motion vector of the block 1320 at the same position of the preceding picture 1112. For example, if the motion vector mv_colB of the block 1320 at the same position as the current block 1010 is generated for the searched block 1322 of the subsequent picture 1114, the motion vector candidates mv_L0B and mv_L1B of the current block 1010 are as follows: Is generated as follows.

mv_L1B = (t3 / t4) * mv_colB
mv_L0B = mv_L1B-mv_colB
Here, mv_L0B means a first direction motion vector candidate of the current block 1010, and mv_L1B means a second direction motion vector candidate of the current block 1010.

  Referring to FIG. 13B, the motion vector candidate of the current block 1010 of the current picture 1110 is determined using the motion vector of the block 1330 at the same position of the preceding picture 1112. For example, if the motion vector mv_colC of the block 1330 at the same position as the current block 1010 is generated for the retrieved block 1332 of the other preceding picture 1116, the motion vector candidate mv_L0C of the current block 1010 is Is generated as follows.

mv_L0C = (t6 / t5) xmv_colC
The mv_L0B, mv_L1B, and mv_L0B described above with reference to FIGS. 13A and 13B are included in the C set that is the motion vector candidate of the current block 1010 described above. Instead of mv_L0A and mv_L1A, they may be included in the C set or additionally included in the C set.

  Referring to FIG. 9 again, if the motion vector determination unit 910 determines the motion vector of the current block based on the motion vector of the block encoded before the current block, the encoding unit 920 Encode information.

  If the first direction motion vector and the second direction motion vector of the current block are determined, the encoding unit 920 may predict the first direction based on the determined first direction motion vector and the second direction motion vector. Perform bi-directional prediction and bi-directional prediction. Next, a prediction direction for predicting the current block most accurately is determined. By comparing the prediction result in the first direction, the prediction result in the second direction, and the bidirectional prediction result with the current block, a prediction direction with the least SAD of the residual block can be determined. The prediction direction may be determined by performing prediction in the first direction, prediction in the second direction, and bidirectional prediction, and comparing the encoded result based on the RD cost (rate distortion cost).

  If the prediction direction is determined, information about the determined prediction direction and information about the pixel value are encoded. Information about the prediction direction is encoded as a sequence parameter, slice parameter or block parameter. A predetermined binary number is assigned to the first direction, the second direction, and both directions, and a binary number corresponding to the prediction direction used for encoding the current block can be entropy-coded and inserted into the bitstream.

  As information about the pixel value, information about the residual block such as the direct prediction mode is separately encoded. A prediction block generated based on a prediction result in a predetermined prediction direction is subtracted from the current block to generate a residual block, the residual block is converted to generate a frequency domain coefficient, and the generated coefficient is quantized. Entropy coding. The transformation is a discrete cosine transformation or a KLT transformation.

  In addition, as information about the pixel value, only the flag information indicating that the skip mode according to the prior art and the prediction block and the current block are the same are encoded. A prediction block generated by a prediction result in a predetermined prediction direction is regarded as the same as the current block, and only flag information indicating that the current block and the prediction block are the same is encoded.

  A picture to be referred to for prediction is inferred based on a reference index of a previously encoded block. As described above with reference to FIG. 11B, the reference number of the current block may be determined based on the reference number of the previously encoded block, and the corresponding reference picture may be determined. Also, the reference picture corresponding to the motion vector determined by the motion vector determination unit 910 is determined as the reference picture of the current block. For example, as described above with reference to FIG. 11A, if mv_L0A is determined as the first direction motion vector of the current block, the preceding picture 1112 by mv_L0A is automatically determined as the reference picture of the current block.

  When the motion vector determination unit 910 explicitly determines the first direction motion vector and the second direction motion vector from a plurality of motion vector candidates as shown in FIGS. 12A and 12B, FIGS. 13A and 13B, encoding is performed. The unit 920 may encode information that indicates at least one of the first direction motion vector and the second direction motion vector of the current block among the plurality of motion vector candidates.

  As a result of determining the prediction direction, when it is determined that the prediction is performed only in the first direction, only the information indicating the first direction motion vector is encoded from the plurality of motion vector candidates. Even when prediction is performed only in the second direction, only information indicating the second direction motion vector can be encoded. However, when bi-directional prediction is performed, information indicating the first direction motion vector and the second direction motion vector can be encoded from a plurality of motion vector candidates.

  A binary number is assigned to each of all the motion vectors included in the set C described above, and a binary number assigned to the first direction motion vector and / or the second direction motion vector defined as the motion vector of the current block. Can be encoded. However, as described above, the first direction motion vector of the current block is determined as one of the first direction motion vectors included in the C set, and thus the first direction motion vector included in the C set. Among the binary numbers assigned in order, the binary number assigned to the motion vector defined as the first direction motion vector of the current block is encoded as information indicating the first direction motion vector. Similarly, the second direction motion vector is the binary number assigned to the motion vector defined as the second direction motion vector of the current block among the binary numbers sequentially assigned to the second direction motion vectors included in the C set. Are encoded as information indicating the second direction motion vector.

  FIG. 14 is a view illustrating a video decoding apparatus according to another embodiment of the present invention. A video decoding apparatus 1400 in FIG. 14 is an apparatus that is provided in the video decoding apparatus 200 in FIG. 2 and the video encoding apparatus 500 in FIG. 5 to perform inter prediction and decode the current block.

  Referring to FIG. 14, a video decoding apparatus 1400 according to an embodiment of the present invention includes a decoding unit 1410, a motion vector determination unit 1420, and a restoration unit 1430.

  The decoding unit 1410 receives a bitstream including data for the current block, and decodes information about the prediction direction. The video decoding apparatus 1400 determines a motion vector of the current block based on the motion vector of at least one block decoded before the current block, and restores the current block based on the determined motion vector In this case, the information about the prediction direction of the current block is decoded before the motion vector of the current block is determined. Information about the prediction direction included in the bitstream is decoded as a sequence parameter, a slice parameter, or a block parameter.

  The encoding / decoding mode that determines the motion vector of the current block based on the motion vector of the previously encoded block, such as the direct prediction mode and the skip mode, encodes the current block using only prediction in a specific direction. Although the encoding / decoding method according to the present invention encodes the current block in the direct prediction mode or the skip mode based on all of the prediction in the first direction, the prediction in the second direction, and the bidirectional prediction. / Decrypt. For this purpose, the video encoding apparatus 900 described above encodes information about the prediction direction and inserts it into the bitstream. The decoding unit 1410 decodes information about the prediction direction inserted into the beast stream by the video encoding device 900.

  The decoding unit 1410 decodes information indicating the motion vector of the current block from a plurality of motion vector candidates together with information on the prediction direction. If the motion vector of the current block is implicitly determined by the motion vector determination method shared between the encoding side and the decoding side, as described above, the motion vector of the current block is already determined. Since it is determined as one by the method, it is not necessary to decode the information indicating the motion vector. However, as described above, a plurality of motion vector candidates are generated based on previously encoded motion vectors of a plurality of blocks, and when a motion vector of a current block is determined, a plurality of motion vector candidates From this, the information for specifying the motion vector of the current block is decoded.

  Also, the decoding unit 1410 decodes information about the pixel value of the current block. The information about the residual block of the current block is decoded, or the flag information indicating that the current block is the same as the prediction block is decoded. The decoding unit 1410 restores the residual block by entropy decoding, inverse quantization, and inverse transformation of the information about the residual block.

  The motion vector determination unit 1420 determines a motion vector of the current block for performing prediction in a predetermined direction based on the information about the prediction direction decoded by the decoding unit 1410. As a result of referring to the information about the decoded prediction direction, if it is determined that the prediction in the first direction is performed, the first direction motion vector is determined, and if it is determined that the prediction in the second direction is performed, the second Determine the direction motion vector. If it is determined that bidirectional prediction is to be performed, a first direction motion vector and a second direction motion vector are determined.

  When the motion vector of the current block is implicitly determined by the shared motion vector determination method between the encoding side and the decoding side, the motion vector of the current block is determined by the shared motion vector determination method. The method for implicitly determining the motion vector of the current block has been described above with respect to FIGS. 11A and 11B.

  However, when determining the motion vector of the current block from a plurality of motion vector candidates, the motion vector of the current block is determined from the plurality of motion vector candidates decoded by the decoding unit 1410 based on the information indicating the current block. Determine. A plurality of motion vector candidates are generated using the motion vector of at least one block decoded before the current block, and a motion vector of the current block is determined from the generated plurality of motion vector candidates.

  When the current block uses only prediction in the first direction, the first direction motion vector is determined from a plurality of motion vector candidates with reference to the information indicating the first direction motion vector decoded by the decoding unit 1410. When the current block uses only the prediction in the second direction, the second direction motion vector is determined from a plurality of motion vector candidates by referring to the information indicating the second direction motion vector decoded by the decoding unit 1410. Determine. When the current block uses bi-directional prediction, a plurality of motion vector candidates are referenced with reference to information indicating the first direction motion vector and information indicating the second direction motion vector decoded by the decoding unit 1410. From the first direction motion vector and the second direction motion vector.

  The restoration unit 1430 restores the current block based on the information about the pixel value decoded by the decoding unit 1410 and the motion vector of the current block determined by the motion vector determination unit 1420.

  The prediction in the first direction, the prediction in the second direction, or the bidirectional prediction is performed using the motion vector determined by the motion vector determination unit 1410 to generate a prediction block of the current block. When the residual block is restored as a result of decoding the information about the pixel value by the decoding unit 1410, the restored block and the prediction block are added to restore the current block. When the decoding unit 1410 decodes the flag information indicating that the prediction block is the same as the current block, the prediction block is used as it is in the restored current block.

  The picture to be referred for prediction is inferred based on the reference number of the previously decoded block. As described above with reference to FIG. 11B, a reference number of a current block may be determined based on a reference number of a previously decoded block, and a corresponding reference picture may be determined. Also, the reference picture corresponding to the motion vector determined by the motion vector determination unit 1410 is determined as the reference picture of the current block. For example, as described above with reference to FIG. 11A, if mv_L0A is determined as the first direction motion vector of the current block, the preceding picture 1112 by mv_L0A is automatically determined as the reference picture of the current block.

  FIG. 15 is a flowchart for explaining a video encoding method according to an embodiment of the present invention. Referring to FIG. 15, in step 1510, the video encoding apparatus determines a motion vector of the current block. A first direction motion vector and a second direction motion vector of a current block included in a current picture that is a bi-predictive picture are defined. As described above with reference to FIGS. 11A and 11B, the motion vector of the current block may be implicitly determined by a motion vector determination method shared between the encoding side and the decoding side, As described above with reference to FIGS. 12A and 12B, and FIGS. 13A and 13B, a plurality of motion vector candidates are generated, and a first direction motion vector and a second direction motion vector are generated from the generated plurality of motion vector candidates. It may be determined.

  In operation 1520, the video encoding apparatus determines a prediction used for encoding the current block among the first direction prediction, the second direction prediction, and the bidirectional prediction. Of the first direction prediction based on the first direction motion vector, the second direction prediction based on the second direction motion vector, and the bidirectional prediction based on the first direction motion vector and the second direction motion vector, prediction used for encoding the current block is performed. Determine.

  Of the first directional prediction, the second directional prediction, and the bidirectional prediction, a prediction that can predict the current block most accurately is defined as a prediction used for encoding the current block. As described above, the prediction with the smallest SAD between the prediction block and the current block is determined as the prediction used for encoding the current block.

  In operation 1530, the video encoding apparatus encodes information about the prediction direction of the prediction determined in operation 1530. A binary number is assigned to each of the first direction, the second direction, and the bidirectional direction, and a binary number corresponding to the prediction direction used for encoding the current block is encoded. The encoded binary number is entropy encoded by a predetermined entropy encoding method. Information about the prediction direction is encoded as a sequence parameter, slice parameter or block parameter.

  Information about the pixel value of the current block is also encoded, but information about the residual value of the residual block generated by subtracting the prediction block from the current block is encoded. Residual blocks are transformed, quantized and entropy coded. As described above, only flag information indicating that the prediction block is the same as the current block may be encoded.

  Information for specifying a motion vector used for encoding the current block is also encoded from a plurality of motion vector candidates. When a plurality of motion vector candidates are generated based on the motion vector of at least one block encoded before the current block, and one of them is selected and used as the motion vector of the current block, the plurality of motion vector candidates The information indicating the motion vector selected from is encoded. If the first direction is determined as the prediction direction of the current block in step 1520, only information about the first direction motion vector is encoded. In step 1520, the second direction is determined as the prediction direction of the current block. Then, only the information about the second direction motion vector is encoded. If bi-directional prediction is determined in the prediction direction of the current block in step 1520, the information about the first direction motion vector and the information about the second direction motion vector are both encoded.

  FIG. 16 is a flowchart for explaining a video decoding method according to an embodiment of the present invention. Referring to FIG. 16, in step 1610, the video decoding apparatus decodes information about a prediction direction used for decoding a current block among a first direction, a second direction, and a bidirectional direction. Decode information about the prediction direction included in the bitstream. The binary numbers assigned to the first direction, the second direction, and the bidirectional direction respectively decode the binary numbers corresponding to the prediction direction used for decoding the current block. Information about the prediction direction included in the bitstream is decoded as a sequence parameter, a slice parameter, or a block parameter.

  In step 1610, the video decoding apparatus decodes information about the pixel value of the current block. The information about the residual value included in the residual block of the current block is decoded. The residual block is restored by entropy decoding, inverse quantization, and inverse transform of the data for the residual block. Information indicating that the current block is the same as the prediction block may be decoded.

  When the motion vector of the current block is determined from the plurality of motion vector candidates described above, information for specifying the motion vector used for decoding the current block is decoded from the plurality of motion vector candidates. As a result of decoding the information on the prediction direction, if the prediction direction of the current block is the first direction, information indicating the first direction motion vector of the current block is decoded from a plurality of motion vector candidates, If the prediction direction is the second direction, information indicating the second direction motion vector of the current block is decoded from a plurality of motion vector candidates. If the prediction direction of the current block is bidirectional, information indicating the first direction motion vector and the second direction motion vector is decoded from a plurality of motion vector candidates.

  In operation 1620, the video decoding apparatus determines a prediction direction of the current block based on the information on the prediction direction decoded in operation 1610. The prediction direction of the current block is determined based on the binary number corresponding to the prediction direction decoded in step 1610. If the prediction direction is determined, at least one motion vector for performing prediction in the determined prediction direction is determined.

  As described above, the motion vector of the current block is implicitly determined by the motion vector determination method shared between the encoding side and the decoding side. In addition, when a motion vector of the current block is explicitly selected from a plurality of motion vector candidates, a plurality of motion vector candidates are generated based on the motion vector of at least one block decoded before the current block. The motion vector of the current block is determined from the generated motion vector candidates. A motion vector of the current block is determined from a plurality of motion vector candidates decoded in step 1610 based on information indicating the motion vector of the current block. At least one of the first direction motion vector and the second direction motion vector is determined based on the information decoded in step 1610.

  In operation 1630, the video decoding apparatus restores the current block. A prediction block is generated based on the motion vector of the current block determined in step 1620, and the current block is restored based on the generated prediction block.

  Based on the first direction motion vector and / or the second direction motion vector of the current block determined in step 1620, one of the first direction prediction, the second direction prediction, and the bidirectional prediction is performed, and Generate a prediction block.

  If the residual block is restored in operation 1610, the current block is restored by adding the generated prediction block and the restored residual block. If the information indicating that the prediction block is the same as the current block is decoded in step 1610, the prediction block becomes the current block.

  As mentioned above, even if this invention is demonstrated with limited embodiment and drawing, this invention is not limited to the said embodiment, Those skilled in the art can perform various correction and deformation | transformation from these description. Is possible. Therefore, the idea of the present invention should be understood only from the scope of the claims, and any equivalent or equivalent modifications can be said to belong to the category of the idea of the present invention. In addition, 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 encoding device, the video decoding device, the motion vector encoding device, and the motion vector decoding device according to exemplary embodiments of the present invention are as shown in FIGS. A bus coupled to each unit of the device, and at least one processor coupled to the bus. It also includes a memory coupled to the bus for storing instructions, received messages or generated messages and coupled to at least one processor for executing instructions as described above.

  The computer-readable recording medium includes all recording devices in which data to be read by a computer system is stored. Examples of the recording medium include ROM, RAM, CD-ROM, magnetic tape, floppy (registered trademark) disk, optical data storage device, and the like. The computer-readable recording medium is distributed to computer systems connected to a network, and computer-readable codes are stored in a distributed manner.

1400 Video decoding device 1410 Decoding unit 1420 Motion vector determining unit 1430 Restoring unit

Claims (3)

In the video decoding method,
Obtaining information about the prediction direction of the current block indicating one of L0 direction, L1 direction, and bidirectional from the bitstream;
Generating motion vector candidates for the current block based on motion vectors of at least one block decoded before the current block;
Acquiring information indicating at least one of the generated motion vector candidates from the bitstream according to information on a prediction direction of the current block;
Based on the information indicating the at least one candidate, the current block using at least one motion vector candidate among the motion vector candidates in the L0 direction and the motion vector candidates in the L1 direction included in the motion vector candidates. Determining at least one motion vector. The step of acquiring information indicating at least one candidate among the generated motion vector candidates from the bitstream includes:
If the information about the prediction direction of the current block indicates the L0 direction, obtaining information indicating one of the motion vector candidates in the L0 direction included in the motion vector candidates;
When the information about the prediction direction of the current block indicates the L1 direction, obtaining information indicating one of the motion vector candidates in the L1 direction included in the motion vector candidates;
When the information about the prediction direction of the current block indicates both directions, information indicating one of the motion vector candidates in the L0 direction included in the motion vector candidates and the L1 included in the motion vector candidates The method according to claim 1, further comprising: obtaining information indicating one of directional motion vector candidates. In a video decoding device,
A decoding unit that decodes information about the prediction direction of the current block indicating one of L0 direction, L1 direction, and bidirectional from the bitstream;
A motion vector determining unit that generates a motion vector candidate of the current block based on a motion vector of at least one block decoded before the current block;
The decoding unit
According to the prediction direction of the current block, information indicating at least one candidate among the generated motion vector candidates is acquired from the bitstream;
The motion vector determination unit
Based on the information indicating the at least one candidate, using the at least one motion vector candidate among the motion vector candidates in the L0 direction and the motion vector candidates in the L1 direction included in the motion vector candidates, A video decoding device, wherein at least one motion vector of a block is determined.

Images