KR102345458B1 - A method of setting advanced motion vector predictor list and an apparatus having the same - Google Patents

Abstract

The present invention relates to a method and apparatus for constructing a predictive motion vector list. A method for constructing a predictive motion vector list according to an embodiment of the present invention includes: obtaining a motion vector for a first direction of a current block; and setting at least one prediction motion vector candidate in the second direction constituting the prediction motion vector list in the two directions by using the motion vector in the first direction.

Description

A method for constructing a predictive motion vector list and an apparatus thereof

The present invention relates to a method and an apparatus for constructing a predictive motion vector list, and more particularly, to a method and an apparatus for constructing a predictive motion vector list using motion vectors.

Recently, the demand for high-resolution and high-quality images such as HD (High Definition) images and UHD (Ultra High Definition) images is increasing in various application fields. Since the amount of data increases relative to the existing image data as the image data becomes high-resolution and high-quality, when transmitting image data using a medium such as an existing wired/wireless broadband line or storing it using an existing storage medium, the transmission Costs and storage costs will increase. High-efficiency image compression techniques can be used to solve these problems that occur as image data becomes high-resolution and high-quality.

In video compression techniques, motion prediction is used to remove temporal redundancy between successive pictures. In order to detect temporal redundancy, a motion of a current block is predicted using a plurality of reference pictures, and a prediction block is generated by performing motion compensation. The motion information includes at least one reference picture index and at least one motion vector.

In addition, in order to obtain motion information, the current block constructs a predicted motion vector list of the current block by performing bi-directional prediction, and using this, a differential motion vector that is a difference value from the motion vector of the current block may be transmitted to the decoder. . In this case, the predictive motion vector list including the predictive motion vectors for each direction is independent of each other. However, as various sizes are used for inter prediction, the correlation between motion information of the current block and motion information of one or more adjacent blocks increases. Accordingly, according to the above-described conventional compression method, when the size of a picture becomes larger than that of a high-quality picture and various sizes are used for motion prediction and motion compensation, the compression efficiency of motion information decreases.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method and apparatus for constructing a predictive motion vector list for improving coding efficiency of inter prediction by using highly correlated information in bidirectional prediction of a current block.

Another object of the present invention is to provide a method and an apparatus for constructing a predictive motion vector list capable of increasing coding efficiency according to whether reference pictures for bidirectional prediction of a current block are identical.

A method of constructing a predictive motion vector list according to an embodiment of the present invention for solving the above problems includes: obtaining a motion vector for a first direction of a current block; and setting at least one prediction motion vector candidate in the second direction constituting the prediction motion vector list in the second direction by using the motion vector for the first direction.

The at least one prediction motion vector candidate in the second direction may be set by copying the motion vector in the first direction, and the reference picture for the first direction and the reference picture for the second direction are the same picture information can have In addition, the prediction motion vector candidates of the second direction may be assigned to the index in the order of having the smallest codeword.

In an embodiment, the prediction motion vector candidate of the second direction may be set by scaling the motion vector for the first direction based on picture information, and the reference picture for the first direction and the second direction The picture information of the reference picture for the reference picture may be different. In addition, the prediction motion vector candidates of the second direction may be assigned to the index in the order of having the smallest codeword.

Prior to the step of setting the predictive motion vector candidates in the at least one or more second directions, determining whether picture information of the reference picture for the first direction and the reference picture for the second direction is the same do.

According to another embodiment of the present invention, there is provided an apparatus for constructing a predictive motion vector list, comprising: a motion vector obtaining unit for obtaining a motion vector for a first direction of a current block; and a second direction prediction motion vector list setting unit configured to set at least one prediction motion vector candidate in the second direction constituting the prediction motion vector list in the two directions by using the motion vector for the first direction.

The second direction prediction motion vector list setting unit may include: a first prediction motion vector candidate setting unit configured to set at least one predictive motion vector candidate in the second direction by using the motion vector for the first direction; and a second prediction motion vector candidate setting unit configured to set at least one prediction motion vector candidate in the second direction using spatial and temporal neighboring blocks of the current block.

The prediction motion vector candidate in the second direction obtained by the first prediction motion vector candidate setting unit may be set by copying the motion vector in the first direction, and the reference picture for the first direction and the second direction The picture information of the reference picture with respect to the direction may be the same.

The prediction motion vector candidate of the second direction obtained by the first prediction motion vector candidate setting unit may be set by scaling the motion vector for the first direction based on picture information, and a reference to the first direction Picture information of a picture and a reference picture with respect to the second direction may be different. In addition, the prediction motion vector candidates in the second direction obtained by the first prediction motion vector candidate setting unit may be allocated to the index in the order of having the smallest codeword.

According to an embodiment of the present invention, inter prediction by using a motion vector in a first direction of a current block for which bidirectional prediction is performed is used to set at least one predictive motion vector candidate when constructing a predictive motion vector list for a second direction. An object of the present invention is to provide a method and apparatus for constructing a prediction motion vector list that uses information with high temporal correlation to improve coding efficiency of inter prediction.

In addition, according to another embodiment of the present invention, it is determined whether reference pictures for bidirectional prediction of the current block are identical, and a motion vector for the first direction is calculated in various ways according to whether the reference pictures are identical in the second direction. To provide a method and an apparatus for constructing a predictive motion vector list capable of increasing coding efficiency by using at least one predictive motion vector candidate during construction.

1 is a schematic block diagram of a video encoding apparatus according to an embodiment of the present invention.
2 is a block diagram schematically illustrating a video decoding apparatus according to an embodiment of the present invention.
FIG. 3 is for explaining a position at which a prediction motion vector candidate (MVP candidate) of a current block is obtained according to a general method.
4 to 5B are for explaining a method of constructing a prediction motion vector list of a current block according to a general method.
6 is a flowchart illustrating a method of constructing a predictive motion vector list according to an embodiment of the present invention.
7 is a flowchart illustrating an apparatus for constructing a predictive motion vector list according to an embodiment of the present invention.
8 and 9 are flowcharts showing a method for constructing a predictive motion vector list and an apparatus for constructing a predictive motion vector list according to another embodiment of the present invention.
10A and 10B are for explaining a method of constructing a predictive motion vector list according to an embodiment of the present invention.
11 is a flowchart illustrating a method of constructing a predictive motion vector list according to another embodiment of the present invention.

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

Examples of the present invention are provided to more completely explain the present invention to those of ordinary skill in the art, and the following examples may be modified in various other forms, and the scope of the present invention is as follows It is not limited to an Example. Rather, these examples are provided so that this disclosure will be more thorough and complete, and will fully convey the spirit of the invention to those skilled in the art.

In addition, in the drawings, the thickness or size of each unit is exaggerated for convenience and clarity of description, and the same reference numerals in the drawings refer to the same elements. As used herein, the term “and/or” includes any one and all combinations of one or more of those listed items.

The terminology used herein is used to describe specific embodiments, not to limit the present invention. As used herein, the singular form may include the plural form unless the context clearly dictates otherwise. Also, as used herein, “comprise” and/or “comprising” refers to the specified presence of the recited shapes, numbers, steps, actions, members, elements, and/or groups thereof. and does not exclude the presence or addition of one or more other shapes, numbers, movements, members, elements and/or groups.

Although the terms first, second, etc. are used herein to describe various components, members, parts, regions, and/or parts, these components, members, parts, regions, and/or parts are used herein to refer to these terms. It is obvious that it should not be limited by These terms are used only to distinguish one component, member, part, region or part from another region or part, and do not limit the order. Accordingly, a first component, member, component, region or portion discussed below may refer to a second component, member, component, region or portion without departing from the teachings of the present invention. Also, and/or terms include combinations of a plurality of related recited items or any of a plurality of related recited items.

When a component is referred to as being “connected” or “connected” to another component, it is not only directly connected or connected to the other component, but also between the component and the other component. It should be understood including the case where other components exist in However, when a component is referred to as being “directly connected” or “directly connected” to another component, there is no other component in the middle and the component and the other component are directly connected or connected to each other. should be understood as being

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings schematically illustrating ideal embodiments of the present invention. In the drawings, for example, the size and shape of the members may be exaggerated for convenience and clarity of description, and in actual implementation, variations of the illustrated shape may be expected. Accordingly, embodiments of the present invention should not be construed as limited to the specific shapes of the regions shown herein.

1 is a block diagram schematically illustrating an image encoding apparatus according to an embodiment of the present invention.

Referring to FIG. 1 , the image encoding apparatus 100 includes a picture divider 105 , an inter prediction unit 110 , an intra prediction unit 115 , a transform unit 120 , a quantization unit 125 , and a rearrangement unit. 130 , an entropy encoding unit 135 , an inverse quantization unit 140 , an inverse transform unit 145 , a filter unit 150 , and a memory 155 .

Each component shown in FIG. 1 is independently illustrated to represent different characteristic functions in the image encoding apparatus, and does not mean that each component is composed of separate hardware or one software component. That is, each component is listed as each component for convenience of description, and at least two components of each component are combined to form one component, or one component is divided into a plurality of components to provide a function. can be done An embodiment in which each of these components is integrated or a separate embodiment may be included in the scope of the present invention without departing from the essential aspect of the present invention.

The picture divider 105 may divide the input picture into at least one processing unit. The processing unit may be a prediction block (hereinafter referred to as 'PU'), a transform block (hereinafter referred to as 'TU'), or a coding block (Coding Unit, hereinafter referred to as 'CU') ) may be However, in the present specification, for convenience of explanation, a prediction block may be expressed as a prediction unit, a transform block may be expressed as a transformation unit, and a coding or decoding block may be expressed as a coding unit or a decoding unit. In an embodiment, the picture dividing unit 105 divides one picture into a combination of a plurality of coding blocks, prediction blocks, and transform blocks, and divides one picture into one picture based on a predetermined criterion (eg, a cost function). A picture may be encoded by selecting a combination of a coding block, a prediction block, and a transform block.

For example, one picture may be divided into a plurality of coding blocks. In an embodiment, one picture may divide the coding block using a recursive tree structure such as a quad tree structure or a binary tree structure. In addition, a coding block divided into other coding blocks with one image or a largest coding unit as a root may be divided having as many child nodes as the number of divided coding blocks.

A coding block that is no longer divided through this process may become a leaf node. For example, if it is assumed that only square division is possible with respect to one coding block, one coding block may be divided into, for example, four coding blocks. However, in the present invention, the coding block, the prediction block, and/or the transform block are not limited to symmetric partitioning when partitioning, and an asymmetric partition is also possible, and not only four partitions but also two partitions are possible. However, the number of divisions is merely exemplary and the present invention is not limited thereto.

The prediction block may also be partitioned in the form of at least one square or non-square having the same size within one coding block, and any of the prediction blocks divided within one coding block. One prediction block may be divided to have a shape and size different from that of the other prediction block. In one embodiment, the coding block and the prediction block may be the same. That is, the prediction may be performed based on the divided coding block without distinguishing the coding block and the prediction block.

The prediction unit may include an inter prediction unit 110 performing inter prediction and an intra prediction unit 115 performing intra prediction. In order to increase coding efficiency, an image is predicted using a specific region inside a picture that has already been encoded and decoded, instead of encoding the image signal as it is, and a residual value between the original image and the predicted image is encoded. Also, prediction mode information, motion vector information, etc. used for prediction may be encoded in the entropy encoder 135 together with a residual value and transmitted to the decoder. In the case of using a specific encoding mode, it is also possible to encode the original block as it is without generating a prediction block through the prediction units 110 and 115 and transmit it to the decoder.

In an embodiment, the prediction units 110 and 115 determine whether inter prediction or intra prediction is to be performed on the prediction block, and the prediction such as an inter prediction mode, a motion vector, and a reference picture. Specific information according to each method may be determined. In this case, a processing unit in which prediction is performed, a prediction method, and a detailed processing unit may be different. For example, although a prediction mode and a prediction method are determined according to a prediction block, prediction may be performed according to a transform block.

The prediction units 110 and 115 may generate a prediction block including samples predicted by performing prediction on a processing unit of the picture divided by the picture division unit 105 . A picture processing unit in the prediction units 110 and 115 may be a coding block unit, a transform block unit, or a prediction block unit.

The inter prediction unit 110 may predict a prediction block based on information on at least one of a picture before or after a picture of the current picture, and in some cases, prediction based on information of a partial region where coding has been completed in the current picture Blocks can be predicted. The inter prediction unit 110 may include a reference picture interpolator, a motion prediction unit, and a motion compensator.

In an embodiment, the information on the one or more pictures used for prediction by the inter prediction unit 110 may be information on pictures that have already been encoded and decoded, or information about pictures that have been transformed and stored in an arbitrary way. have. For example, the picture transformed and stored by the arbitrary method may be a picture obtained by enlarging or reducing a picture that has been encoded and decoded, or a picture in which the brightness of all pixel values in the picture is changed or the color format is changed. may be

The reference picture interpolator may receive reference picture information from the memory 155 and generate pixel information of integer pixels or less in the reference picture. In the case of a luminance pixel, pixel information of less than an integer may be generated in units of 1/4 pixels using a DCT-based 8-tap interpolation filter with different filter coefficients. In the case of a color difference signal, pixel information of less than an integer may be generated in units of 1/8 pixel by using a DCT-based interpolation filter that has different filter coefficients. However, the type of filter and the unit for generating pixel information less than or equal to an integer are not limited thereto, and a unit for generating pixel information less than or equal to an integer may be determined by using various interpolation filters.

The motion prediction unit may perform motion prediction based on the reference picture interpolated by the reference picture interpolator. Various methods may be used to calculate the motion vector. The motion vector may have a motion vector value in integer pixel units or in 1/2 or 1/4 pixel units based on interpolated pixels. In an embodiment, the motion prediction unit may predict the prediction unit of the current block by using a different motion prediction method. Various methods may be used as the motion prediction method, including a merge method, an advanced motion vector prediction (AMVP) method, and a skip method. As described above, information including the index of the reference picture selected by the inter prediction unit 110, the prediction motion vector (MVP), and the residual signal may be entropy-coded and transmitted to the decoder.

The predicted motion vector (MVP) may be selected from predicted motion vector candidates by selecting MVP candidates in various ways. Also, at least one or more prediction motion vector candidates may constitute a prediction motion vector list, and the decoding apparatus may also obtain prediction motion vector information for inter prediction of a current block from the prediction motion vector list.

If the current block performs bidirectional prediction, the prediction motion vector list may include prediction motion vector candidates for each direction. As described above, as various directions are used for inter prediction, correlation between reference pictures in each direction and motion information of a prediction block may increase. In this case, a method for constructing the predictive motion vector list according to an embodiment of the present invention and an apparatus thereof for increasing coding efficiency will be described later with reference to FIGS. 3 to 11 .

Unlike inter prediction, the intra prediction unit 115 may generate a prediction block based on reference pixel information around the current block, which is pixel information in the current picture. When the neighboring blocks of the prediction block are blocks on which inter prediction is performed, that is, when the reference pixel is a pixel on which inter prediction is performed, the reference pixel included in the block on which inter prediction is performed is predicted as the neighboring blocks. It can also be used by replacing it with reference pixel information of a block that has performed .

Also, the intra prediction unit 115 may use the most probable intra prediction mode (MPM) obtained from neighboring blocks to encode the intra prediction mode. According to various embodiments of the present invention, the most probable intra prediction mode list (MPM List) composed of the most probable intra prediction modes may be configured in various ways.

Even when the intra prediction unit 115 performs intra prediction, a processing unit in which prediction is performed and a processing unit in which a prediction method and specific content are determined may be different from each other. For example, a prediction mode may be determined as a prediction unit (PU) and prediction may be performed in the prediction unit, or the prediction mode may be determined as a prediction unit, but prediction may be performed in a transform unit (TU). In an embodiment, a prediction mode may be determined in units of coding blocks (CUs), and prediction may be performed in units of coding blocks because the units of coding blocks and prediction units are the same.

The prediction mode of intra prediction may include 65 directional prediction modes and at least two non-directional modes. The non-directional mode may include a DC prediction mode and a planar mode. The number of the 67 inter prediction modes is only an example, and the present invention is not limited thereto. In order to make predictions in various ways, intra prediction may be performed in more directional or non-directional modes.

In an embodiment, intra prediction may generate a prediction block after applying a filter to a reference pixel. In this case, whether to apply the filter to the reference pixel may be determined according to the intra prediction mode and/or size of the current block.

A prediction unit (PU) may be determined in various sizes and shapes from a coding unit (CU) that is no longer split. For example, in the case of inter prediction, the prediction unit may have a size such as 2N x 2N, 2N x N, N x 2N, or N x N. In the case of intra prediction, the prediction unit may have a size such as 2N x 2N or N x N (where N is an integer), but intra prediction can be performed not only with such a forward size but also with a non-forward size shape. In this case, the N x N prediction unit may be set to be applied only in a specific case. In addition to the above-mentioned size of the prediction unit, an intra prediction unit having a size such as N x mN, mN x N, 2N x mN, or mN x 2N (m is a fraction or an integer) may be further defined and used.

A residual value (a residual block or a residual signal) between the prediction block generated by the intra prediction unit 115 and the original block may be input to the transform unit 120 . Also, prediction mode information, interpolation filter information, etc. used for prediction may be encoded by the entropy encoder 135 together with a residual value and transmitted to a decoder.

The transform unit 120 converts an original block as a transform unit and a residual block including residual value information of a prediction unit generated through the prediction units 110 and 115 to DCT (Discrete Cosine Transform), DST (Discrete Sine Transform) , can be transformed using a transformation method such as Karhunen Loeve Transform (KLT). Whether to apply DCT, DST, or KLT to transform the residual block may be determined based on intra prediction mode information of a prediction unit used to generate the residual block.

The transform block in the transform unit 120 may be a TU, and may include a square structure, a non-square structure, a square quad tree structure, and a non-square quad tree. ) structure or a binary tree structure. In an embodiment, the size of the transformation unit may be determined within a range of a predetermined maximum and minimum size. In addition, one transform block may be further divided into sub-transform blocks, and the sub-transform blocks have a square structure, a non-square structure, a square quad tree structure, and a non-square quad. It may have a tree (non-square quad tree) structure or a binary tree (binary tree) structure.

The quantization unit 125 may quantize the residual values transformed by the transform unit 120 to generate a quantization coefficient. In an embodiment, the transformed residual values may be values transformed in the frequency domain. The quantization coefficient may be changed according to the transform unit or the importance of the image, and the value calculated by the quantization unit 125 may be provided to the inverse quantization unit 140 and the rearrangement unit 130 .

The reordering unit 130 may rearrange the quantization coefficients provided from the quantization unit 125 . The reordering unit 130 may improve encoding efficiency in the entropy encoding unit 135 by rearranging the quantization coefficients. The reordering unit 130 may rearrange the quantized coefficients in the form of a two-dimensional block into a form of a one-dimensional vector through a coefficient scanning method. As for the coefficient scanning method, it may be determined which scanning method is used according to the size of the transform unit and the intra prediction mode. The coefficient scanning method may include a zig-zag scan, a vertical scan for scanning two-dimensional block-shaped coefficients in a column direction, and a horizontal scan for scanning two-dimensional block-shaped coefficients in a row direction. In an embodiment, the reordering unit 130 may increase the entropy encoding efficiency of the entropy encoding unit 135 by changing the order of coefficient scanning based on probabilistic statistics of coefficients transmitted from the quantization unit.

The entropy encoding unit 135 may perform entropy encoding on the quantization coefficients rearranged by the reordering unit 130 . For entropy encoding, various encoding methods such as Exponential Golomb, Context-Adaptive Variable Length Coding (CAVLC), and Content-Adaptive Binary Arithmetic Coding (CABAC) may be used.

The entropy encoding unit 135 includes quantization coefficient information and block type information, prediction mode information, division unit information, prediction unit information and transmission unit information of the coding unit received from the reordering unit 130 and the prediction units 110 and 115, Various information such as motion vector information, reference picture information, interpolation information of a block, and filtering information may be encoded. Also, according to an embodiment, the entropy encoder 135 may apply a certain change to a transmitted parameter set or syntax, if necessary.

The inverse quantization unit 140 inverse quantizes the values quantized by the quantization unit 125 , and the inverse transform unit 145 inversely transforms the values inverse quantized in the inverse quantization unit 140 . The residual values generated by the inverse quantizer 140 and the inverse transform unit 145 may be combined with the prediction blocks predicted by the predictors 110 and 115 to generate a reconstructed block. The image composed of the generated reconstructed blocks may be a motion compensated image or an MC image (Motion Compensated Picture).

The motion compensation image may be input to the filter unit 150 . The filter unit 150 may include a deblocking filter unit, an offset correction unit (Sample Adaptive Offset, SAO), and an adaptive loop filter unit (ALF). In summary, the motion compensation image is deblocking After the deblocking filter is applied in the filter unit to reduce or remove blocking artifacts, it may be input to the offset correcting unit to correct the offset. The picture output from the offset correction unit may be input to the adaptive loop filter unit and pass through an adaptive loop filter (ALF) filter, and the picture passing through the filter may be transmitted to the memory 155 .

In detail with respect to the filter unit 150 , the deblocking filter unit may remove distortion within a block generated at a boundary between blocks in a reconstructed picture. In order to determine whether to perform deblocking, it may be determined whether to apply the deblocking filter to the current block based on pixels included in several columns or rows included in the block. When a deblocking filter is applied to a block, a strong filter or a weak filter may be applied according to the required deblocking filtering strength. In addition, in applying the deblocking filter, horizontal filtering and vertical filtering may be concurrently processed when vertical filtering and horizontal filtering are performed.

The offset correcting unit may correct an offset with respect to the residual block to which the deblocking filter is applied in units of pixels from the original image. In order to correct the offset for a specific picture, a method of dividing pixels included in an image into a certain number of regions, determining an region to be offset, and applying the offset to the region (Band Offset) or the edge of each pixel It may be applied in the form of a method of applying an offset in consideration of information (Edge Offset). However, in an embodiment, the filter unit 150 may not apply filtering to the reconstructed block used for inter prediction.

The adaptive loop filter (ALF) may be performed only when high efficiency is applied based on a value obtained by comparing the filtered reconstructed image and the original image. After dividing the pixels included in the image into a predetermined group, one filter to be applied to the corresponding group may be determined and filtering may be performed differentially for each group. As for information related to whether to apply the ALF, the luminance signal may be transmitted for each coding unit (CU), and the shape and filter coefficients of the ALF filter to be applied may vary according to each block. Also, the ALF filter of the same type (fixed type) may be applied regardless of the characteristics of the application block.

The memory 155 may store the reconstructed block or picture calculated through the filter unit 150 . The reconstructed block or picture stored in the memory 155 may be provided to the inter prediction unit 110 or the intra prediction unit 115 that performs inter prediction. The pixel values of the reconstructed blocks used in the intra prediction unit 115 may be data to which the deblocking filter unit, the offset corrector, and the adaptive loop filter unit are not applied.

2 is a block diagram schematically illustrating an image decoding apparatus according to an embodiment of the present invention. Referring to FIG. 2 , the image decoding apparatus 200 includes an entropy decoding unit 210 , a reordering unit 215 , an inverse quantization unit 220 , an inverse transform unit 225 , an inter prediction unit 230 , and an intra prediction unit. It includes a unit 235 , a filter unit 240 , and a memory 245 .

When an image bitstream is input from the image encoding apparatus, the input bitstream may be decoded by a reverse process of a procedure of processing image information in the encoding apparatus. For example, when variable length coding (VLC, hereinafter referred to as 'VLC') such as CAVLC is used to perform entropy encoding in the image encoding apparatus, the entropy decoding unit 210 also performs the entropy encoding in the encoding apparatus. Entropy decoding can be performed by implementing the same VLC table as the used VLC table. In addition, when CABAC is used to perform entropy encoding in the encoding apparatus, the entropy decoding unit 210 may perform entropy decoding using CABAC in response thereto.

The entropy decoding unit 210 provides information for generating a prediction block among the decoded information to the inter prediction unit 230 and the intra prediction unit 235, and the entropy decoding unit performs entropy decoding on the residual value. may be input to the rearrangement unit 215 .

The reordering unit 215 may rearrange the entropy-decoded bitstream by the entropy decoding unit 210 based on a method in which the image encoder rearranges the bitstream. The reordering unit 215 may receive information related to coefficient scanning performed by the encoding apparatus, and may perform rearrangement through a method of scanning inversely based on the scanning order performed by the encoding apparatus.

The inverse quantizer 220 may perform inverse quantization based on the quantization parameter provided by the encoding apparatus and the reordered coefficient values of the blocks. The inverse transform unit 225 may perform inverse DCT, inverse DST, or inverse KLT on DCT, DST, or KLT performed by the transform unit of the encoding apparatus on the quantization result performed by the image encoding apparatus. Inverse transform may be performed based on a transmission unit or an image division unit determined by the encoding apparatus. The transform unit of the encoding apparatus may selectively perform DCT, DST, or KLT according to information such as a prediction method, a size of a current block, and a prediction direction, and the inverse transform unit 225 of the decoding apparatus performs the inverse transformation in the transform unit of the encoding apparatus. An inverse transformation method may be determined based on the performed transformation information to perform the inverse transformation.

The prediction units 230 and 235 may generate a prediction block based on information related to generation of a prediction block provided from the entropy decoding unit 210 and previously decoded block and/or picture information provided from the memory 245 . The reconstructed block may be generated using the prediction block generated by the prediction units 230 and 235 and the residual block provided by the inverse transform unit 225 . The specific prediction method performed by the prediction units 230 and 235 may be the same as the prediction method performed by the prediction units 110 and 115 of the encoding apparatus.

The prediction units 230 and 235 may include a prediction unit determiner (not shown), an inter prediction unit 230 , and an intra prediction unit 235 . The prediction unit determining unit receives various information such as prediction unit information input from the entropy decoder 210, prediction mode information of the intra prediction method, and motion prediction related information of the inter prediction method, and receives a prediction block in the current coding block. , and it can be determined whether the prediction block performs inter prediction or intra prediction.

The inter prediction unit 230 uses information necessary for inter prediction of the current prediction block provided from the video encoder, and based on the information included in at least one of the pictures before and after the current picture including the current prediction block. can perform inter prediction for the current prediction block.

Specifically, in inter prediction, a prediction block for the current block may be generated by selecting a reference picture for the current block and selecting a reference block for the current block. In this case, in order to use the information of the reference picture, information on neighboring blocks of the current picture may be used. For example, a prediction block for the current block may be generated based on information on the neighboring block by using a skip mode, a merge mode, and a method such as AMVP (Advanced Motion Vector Prediction).

The current block may construct a predictive motion vector list by selecting a predictive motion vector candidate using temporal and spatial neighboring blocks of the current block. In addition, the motion vector of the current block may be decoded by using the differential motion vector (MVD) and index information on the prediction motion vector candidate selected as the prediction motion vector of the current block received from the encoding apparatus.

If the current block performs bidirectional prediction, the prediction motion vector list may include prediction motion vector candidates for each direction. As described above, as various directions are used for inter prediction, correlation between reference pictures and motion information of a prediction block in each direction may increase, so that prediction motion vector candidates may be selected by reflecting the correlation. As described above, a method for constructing the predictive motion vector list according to an embodiment of the present invention for increasing coding efficiency and an apparatus thereof will be described later with reference to FIGS. 3 to 11 .

The prediction block may be generated in units of samples equal to or less than an integer, such as 1/2 pixel sample unit and 1/4 pixel sample unit. In this case, the motion vector may also be expressed in units of integer pixels or less. For example, the luminance pixel may be expressed in units of 1/4 pixels and the chrominance pixels may be expressed in units of 1/8 pixels.

Motion information including a motion vector and a reference picture index necessary for inter prediction of the current block may be derived by checking a skip flag, a merge flag, etc. received from the encoding apparatus, and corresponding thereto.

The intra prediction unit 235 may generate a prediction block based on pixel information in the current picture. When the prediction unit is a prediction unit on which intra prediction is performed, intra prediction may be performed based on intra prediction mode information of the prediction unit provided by the image encoder. When the neighboring blocks of the prediction unit are blocks on which inter prediction is performed, that is, when the reference pixel is a pixel on which inter prediction is performed, a reference pixel included in the block on which inter prediction is performed is predicted as the neighboring blocks. It can also be used by replacing it with reference pixel information of a block that has performed .

Also, the intra prediction unit 235 may use the most probable intra prediction mode (MPM) obtained from neighboring blocks to encode the intra prediction mode. In an embodiment, the most probable intra prediction mode may use an intra prediction mode of a spatial neighboring block of the current block.

In an embodiment, a processing unit in which prediction is performed by the intra prediction unit 235 and a processing unit in which a prediction method and specific content are determined may be different from each other. For example, a prediction mode may be determined in a prediction unit and prediction may be performed in a prediction unit, or a prediction mode may be determined in a prediction unit and intra prediction may be performed in a transformation unit.

In this case, the prediction block PU may be determined in various sizes and shapes from the coding block CU that is no longer split. For example, in the case of intra prediction, the prediction block may have a size such as 2N x 2N or N x N (N is an integer). , 2N x mN or mN x 2N (m is a fraction or an integer) can also perform intra prediction. In this case, the N x N prediction unit may be set to be applied only in a specific case.

In addition, the transform block (TU) may also be determined in various sizes and shapes. For example, the transform block may have a size such as 2N x 2N or N x N (N is an integer), but not only such a forward size but also a non-forward size shape of N x mN, mN x N, 2N x mN, or In-picture prediction can also be performed with mN x 2N (m is a fraction or an integer). In this case, the N x N prediction unit may be set to be applied only in a specific case. In one embodiment, the transform block is a square structure, a non-square structure, a square quad tree structure, a non-square quad tree structure, or a binary tree ( It may be one of blocks having a binary tree) structure. In an embodiment, the size of the transform block may be determined within a range of a predetermined maximum and minimum size. In addition, one transform block may be divided into sub-transform blocks. In this case, the sub-transform blocks also have a square structure, a non-square structure, a square quad tree structure, and a non-transform block. It may be divided into a non-square quad tree structure or a binary tree structure.

The intra prediction unit 235 may include an Adaptive Intra Smoothing (AIS) filter unit, a reference pixel interpolator unit, and a DC filter unit. The AIS filter unit is a part that performs filtering on the reference pixel of the current block, and may determine whether to apply the filter according to the prediction mode of the current prediction unit and apply the filter. AIS filtering may be performed on the reference pixel of the current block by using the prediction mode and AIS filter information of the prediction unit provided by the image encoder. When the prediction mode of the current block is a mode in which AIS filtering is not performed, the AIS filter unit may not be applied to the current block.

When the prediction mode of the prediction unit is a prediction unit that performs intra prediction based on a sample value obtained by interpolating the reference pixel, the reference pixel interpolator interpolates the reference pixel to generate a reference pixel of a pixel unit having an integer value or less. have. When the prediction mode of the current prediction unit is a prediction mode that generates a prediction block without interpolating the reference pixel, the reference pixel may not be interpolated. When the prediction mode of the current block is the DC mode, the DC filter unit may generate the prediction block through filtering.

The reconstructed block and/or picture may be provided to the filter unit 240 . The filter unit 240 may include a deblocking filter unit, an offset correction unit (Sample Adaptive Offset) and/or an adaptive loop filter unit in the reconstructed block and/or picture. The deblocking filter unit may receive information indicating whether a deblocking filter is applied to a corresponding block or picture from an image encoder and information indicating whether a strong filter or a weak filter is applied when the deblocking filter is applied. The deblocking filter unit may receive the deblocking filter related information provided from the image encoder, and the image decoder may perform deblocking filtering on the corresponding block.

The offset correction unit may perform offset correction on the reconstructed image based on the type of offset correction applied to the image during encoding and information on the offset value. The adaptive loop filter unit may be applied as a coding unit based on information such as information on whether or not the adaptive loop filter is applied and information on coefficients of the adaptive loop filter provided from the encoder. The information related to the adaptive loop filter may be provided in a specific parameter set.

The memory 245 may store the reconstructed picture or block to be later used as a reference picture or reference block, and may also provide the reconstructed picture to an output unit.

Although omitted herein for convenience of description, the bitstream input to the decoding apparatus may be input to the entropy decoding unit through a parsing step. Also, the entropy decoding unit may perform a parsing process.

In the present specification, coding may be interpreted as encoding or decoding in some cases, and information includes all values, parameters, coefficients, elements, flags, and the like. can be understood as 'Screen' or 'picture' generally refers to a unit representing one image in a specific time period, and 'slice' and 'frame' are It is a unit constituting a part, and may be used interchangeably with a picture if necessary.

A 'pixel', 'pixel' or 'pel' represents the smallest unit constituting one image. Also, as a term indicating a value of a specific pixel, a 'sample' may be used. A sample may be divided into a luminance (Luma) and a chroma (Chroma) component, but in general, a term including both of them may be used. In the above, the color difference component represents a difference between predetermined colors and is generally composed of Cb and Cr.

A 'unit' refers to a basic unit of image processing or a specific position of an image, such as the above-described coding unit, prediction unit, and transformation unit, and in some cases, terms such as 'block' or 'area' and may be used interchangeably. Also, a block may be used as a term indicating a set of samples or transform coefficients composed of M columns and N rows.

FIG. 3 is for explaining a position at which a prediction motion vector candidate (MVP candidate) of a current block is obtained according to a general method.

Referring to FIG. 3 , in order to construct a prediction motion vector list (MVP list), the current block uses motion information of spatial neighboring blocks (A0, A1, B0, B1) and motion information of temporal neighboring blocks (T0, T1). can The motion information of the spatial neighboring block may be determined using motion information of one of the neighboring blocks located on the left side of the current block and motion information of one of the neighboring blocks located above the current block. In addition, the motion information of the temporal neighboring block may be determined using motion information of a neighboring block located at the lower right of the current block or motion information of a block located at the same position as the current block inside a reference image to be referenced by the current block. .

Motion information of a spatial neighboring block may be searched for motion information while scanning in the order of A0->A1->scaled A0->scaled A1 with respect to neighboring blocks located on the left side of the current block. Thereafter, motion information is searched for while scanning the neighboring blocks located above the current block in the order B0->B1->B2. In an embodiment, if the current block scans the blocks A0 and A1 but the reference image to be referenced by the current block is different from the reference image referenced by the motion information of the AO and A1 blocks, the current block may fit the reference image to be referenced Motion information of the scaled AO and A1 blocks may be used.

The motion information of the temporal neighboring block is scanned in the order of T0 and T1, and even in this case, the motion vector of the temporal neighboring block may be used by scaling the image referenced by the current block.

In one embodiment, Advanced Motion Vector Prediction (AMVP) may use two predictive motion vectors. First, the motion information of the spatial neighboring block is scanned and input to the predictive motion vector list (AMVP list). In this process, if the list is not filled, the list can be filled by scanning the motion information of the temporal neighboring block. If the same motion information is input to the prediction motion vector list when the motion information of the neighboring block is scanned, the overlapping motion information is deleted. Through this process, when the predicted motion vector list is not fully filled even after the motion information scan of the temporal and spatial neighboring blocks is finished, the unfilled list is filled with (0,0) to complete the predicted motion vector list.

4 to 5B are for explaining a method of constructing a prediction motion vector list of a current block according to a general method.

Referring to FIG. 4 , when the current block CB performs bidirectional prediction, a motion vector may be obtained from a reference picture 1 for a first direction, and a motion vector may be obtained from a reference picture 2 for a second direction. can be obtained. As shown at the bottom of FIG. 4 , an AMVP list for inter prediction of the current block may be configured to include at least one predictive motion vector candidate (MVP candidate) for each direction. Thereafter, a differential motion vector may be obtained and encoded by calculating a difference value between a motion vector of a current block and one predicted motion vector selected from among the prediction motion vector candidates in the prediction motion vector list.

In an embodiment, the selected one prediction motion vector may be selected from among prediction motion vector candidates included in the prediction motion vector list, the one having the highest encoding efficiency. The selected predicted motion vector may be encoded in the form of index information indicating it and transmitted together with the differential motion vector.

5A is a diagram illustrating a method of constructing a prediction motion vector list of a current block according to a general method when reference images 20a and 30a in both directions referenced by the current block 10 are the same, and FIG. 5B is a diagram illustrating the current block A method of constructing a prediction motion vector list of a current block according to a general method when reference images 20b and 30b in both directions referenced by (10) are different will be described.

Referring to FIG. 5A , the reference image 20a referenced by the current block 10 in the first direction and the reference image 30a referenced in the second direction for inter prediction by the current block 10 may have the same POC 8 . As such, when the reference images 20a and 30a in both directions referenced by the current block 10 are the same, MV _L0 which is a motion vector for the first direction L0 of the current block 10 and the second direction L1 ), the motion vector for MV _L1 , can be very similar. However, the prediction motion vector list of the current block according to the general method does not reflect this, and motion information is independently obtained from neighboring blocks of the current block in each direction to construct the prediction motion vector list as shown in Table 1 below.

index Prediction motion vector list in the first direction (AMVP_L0) Second direction prediction motion vector list (AMVP_L1) 0 MV_A0 _L0 =(4,1) MV_A0 _L1 =(1,1) One MV_Col _L0 =(0,1) MV_Col _L1 =(0,1)

When the reference picture 20a in the first direction and the reference picture 30a in the second direction with respect to the current block 10 are the same, there is a high possibility that motion vectors for each direction are similar. Referring back to FIG. 4A , the motion vector MV _L0 for the first direction and the motion vector MV _L1 for the second direction of the current block 10 are (2,1) and (2,2) respectively. similarity can be seen. However, as mentioned above, according to a general method of constructing a predictive motion vector list, a predictive motion vector list for each direction is independently constructed.

Therefore, in order to construct the prediction motion vector list in the second direction, motion vectors of neighboring blocks of the current block 10 having relatively low correlation _{with the motion vector MV L1 in the second direction are used to construct the prediction motion vector list in the second direction.} The encoding efficiency of the motion vector MV _{L1 for} ? may be lowered. However, the predictive motion vector list according to the general method constructs a list independently for each direction, and MVD _L0 = (2 , 0) and MVD _L1 = (2, 1) may be obtained and transmitted to the decoding device.

Referring to FIG. 5B , the current block 10 is a prediction motion vector according to a general method even when the reference picture 20b in the first direction referenced by the current block 10 and the reference picture 30b in the second direction are different from each other. In constructing the list, the predicted motion vector list for each direction may be independently constructed. The constructed prediction motion vector list is shown in Table 2 below.

index Prediction motion vector list in the first direction (AMVP_L0) Second direction prediction motion vector list (AMVP_L1) 0 MV_A1 _L0 =(-2,-3) MV_A1 _L1 =(0,6) One MV_B0 _L0 =(-1,-11) MV_B0 _L1 =(-2,11)

Even if the reference picture 20b in the first direction and the reference picture 30b in the second direction with respect to the current block 10 are not the same, since they are the pictures referred to by the current block 10, the distance and relevance of the reference pictures Accordingly, it cannot be excluded that the motion vectors for each direction are similar. However, as mentioned above, according to a general method of constructing a predictive motion vector list, a predictive motion vector list for each direction is independently constructed.

As shown in FIG. 5B , the motion vector (MV _L0 ) for the first direction and the motion vector (MV _L1 ) for the second direction are (-5,-8) and (4,10), respectively, as shown in Table 2 A predictive motion vector list may be constructed as described. In this case, when AMVP_L0_0 and AMVP_L1_1 are selected as prediction motion vectors, respectively, the differential motion vectors MVD _L0 and MVD _L1 transmitted to the decoding apparatus may be (-3,-5) and (6,-1), respectively.

In this way, when constructing the predictive motion vector list in a general method, by using motion information of neighboring blocks of the current block when constructing the predictive motion vector list for the second direction, the reference picture in the second direction is larger than the current picture. When the correlation with the reference picture in the first direction is relatively high, the encoding efficiency of the motion vector may be lowered.

Therefore, in the method and apparatus for constructing a predictive motion vector list (AMVP List) according to an embodiment of the present invention, when the current block performs bidirectional prediction, the second direction using the motion vector for the first direction We propose to construct a predictive motion vector list.

6 and 7 are flowcharts and apparatus for explaining a method of constructing a predictive motion vector list according to an embodiment of the present invention.

6 and 7 , the prediction motion vector list (AMVP list) construction unit 700 includes a first direction prediction motion vector list setting unit 710 , a motion vector obtainer 720 , and a second direction prediction motion A vector list setting unit 730 may be included. The first direction prediction motion vector list setting unit 710 may set the prediction motion vector list AMVP_L0 in the first direction. The prediction motion vector list in the first direction may include a prediction motion vector candidate (MVP Candidate) in the first direction obtained from motion information of temporal and spatial neighboring blocks of the current block. The predictive motion vector list in the first direction may include two or more predictive motion vector candidates, and an index indicating each predictive motion vector candidate may be assigned. The prediction motion vector list in the first direction may be configured according to the method described with reference to FIG. 3 , but the present invention is not limited thereto. Also, the motion information obtaining unit 720 may obtain a motion vector MV _L0 for the first direction (S10). The motion vector may follow a method of obtaining a motion vector for a current block during inter prediction of a conventional video codec, but the present invention is not limited thereto.

Thereafter, the second direction prediction motion vector list setting unit 730 may set the prediction motion vector list AMVP_L1 in the second direction ( S20 ). At least one of the prediction motion vector candidates in the second direction constituting the prediction motion vector list in the second direction may be set using the _{motion vector MV L0 for the first direction.} In an embodiment, the predicted motion vector candidate in the second direction set using the motion vector for the first direction may be set by copying the motion vector for the first direction as it is, or in the first direction. It may also be set by modifying the motion vector for . Also, the prediction motion vector candidate in the second direction may be included in the prediction motion vector list AMVP_L1 in the second direction.

Since the reference pictures used for bidirectional prediction of the current block are highly likely to have high correlation with each other, the motion vectors for the first direction and the motion vectors MV _L0 and MV _L1 for the second direction obtained in both directions are similar. highly likely to do Accordingly, when obtaining at least one predicted motion vector candidate in the second direction by using the motion vector MV _{L0 for the first direction, the differential motion vector (} MVD _L1 ) can be encoded and transmitted.

In addition, the second direction prediction motion vector list setting unit 730 obtains at least one prediction motion vector candidate in the second direction using motion vectors of the temporal neighboring block and the spatial neighboring block of the current block at the same time to obtain the first The prediction motion vector list AMVP_L1 in the second direction may be configured together with the prediction motion vector candidates of the second direction obtained by using the motion vector for the direction. In the present invention, the predicted motion vector candidates in the second direction set using the motion vector for the first direction and the number of predicted motion vector candidates in the second direction set in a general method, the acquisition order, and the predicted motion vector candidates The method of allocating indexes to the fields is not limited.

8 and 9 are flowcharts showing a method for constructing a predictive motion vector list and an apparatus for constructing a predictive motion vector list according to another embodiment of the present invention.

Referring to FIG. 8 , as described with reference to FIGS. 6 and 7 , first, a motion vector for the first direction of the current block may be obtained ( S10 ). Acquisition of the motion vector for the first direction may be performed irrespective of the order in which the prediction motion vector list of the first direction is constructed. It may be performed after obtaining the motion vector for the first direction through the construction of the prediction motion vector list in the first direction, and may be obtained through information received independently of the construction of the prediction motion vector list in the first direction Also, the present invention is not limited thereto.

Referring to FIG. 9 together with FIG. 8 , the second prediction motion vector list setting unit 730 includes a first prediction motion vector candidate setting unit 731 and a second prediction motion vector candidate setting unit 732 . The first prediction motion vector candidate setting unit 731 sets first prediction motion vector candidates, and the first prediction motion vector candidates use a motion vector MV _L0 for the first direction to predict motion in the second direction. The predicted motion vector candidates may be set as predicted motion vector candidates constituting the vector list (S21). The first predictive motion vector candidate may be at least one predictive motion vector candidate.

The first prediction motion vector candidate may have the highest correlation with the motion vector of the current block among the prediction motion vector candidates. Accordingly, when constructing the first prediction motion vector list, it is possible to increase coding efficiency by allocating the first prediction motion vector candidate to an index having the smallest codeword. In an embodiment, if there are at least two candidates for the first prediction motion vector, coding efficiency may be increased by allocating indexes to the first prediction motion vector candidates in the order of having the smallest codeword.

The second prediction motion vector candidate setting unit 732 also uses spatial and temporal neighboring blocks of the current block independently of the first prediction motion vector candidate setting unit 731 to obtain a prediction motion vector in the second direction, regardless of order. At least one or more predictive motion vector candidates constituting the list may be set ( S22 ). The one or more prediction motion vector candidates may be referred to as a second prediction motion vector candidate. The second predictive motion vector candidate is obtained by the method of obtaining a general predictive motion vector described with reference to FIG. 3, and together with the first predictive motion vector candidate, a predictive motion vector list (AMVP_L1) in the second direction can be formed. have. In this case, when constructing the prediction motion vector list for the second direction, the number, acquisition order, and index allocation method of the first prediction motion vector candidate and the second prediction motion vector candidate are not limited, and those skilled in the art can implement It's free in any way possible.

As described above, in the method and apparatus for constructing a predictive motion vector list according to an embodiment of the present invention, when the current block performs bidirectional inter prediction, at least one of the predictive motion vector candidates in the second direction is selected in the first direction. Coding efficiency can be improved by acquiring using a motion vector for .

10A and 10B are for explaining a method of constructing a predictive motion vector list according to an embodiment of the present invention.

Referring to FIG. 10A , when the current block 10 performs bidirectional prediction and the pictures 40a and 50a referenced in the first direction and the second direction are the same as POC=8, the motion vector for the first direction (MV _L0 ) may be used to construct a prediction motion vector list in the second direction. For example, when the motion vector (MV _{L0 ) for the first direction of the current block is (2,1), MV L0} =(2,1) may be set as the first prediction motion vector candidate in the second direction. . In an embodiment, the first prediction motion vector candidate may have the shortest codeword among indices constituting the prediction motion vector list in the second direction, but the present invention is not limited thereto. It is okay to allocate to any index in the list.

Referring to FIG. 5A together with FIG. 10A , under the same condition that images referenced in each direction during bidirectional prediction of the current block 10 are the same, motion information for the first direction in order to construct a prediction motion vector list in the second direction In the case of obtaining and configuring motion information from neighboring blocks of the current block independently of , the differential motion vector in the second direction to be transmitted may be (2,1). However, when the motion vector for the first direction is used as the first prediction motion vector candidate in the second direction, the differential motion vector in the second direction may be (0,1). The configuration of the AMVP list according to an embodiment of the present invention is shown in Table 3 below.

index Prediction motion vector list in the first direction (AMVP_L0) Second direction prediction motion vector list (AMVP_L1) 0 MV_A1 _L0 =(-2,-3) MV _L0 =(2,1) One MV_B0 _L0 =(-1,-11) MV_B0 _L1 =(-2,11)

As described above, since the motion vector for the first direction and the motion vector for the second direction have a high correlation, the method of the present invention for setting the first predicted motion vector in the second direction by using the motion vector for the first direction In the method of constructing the predictive motion vector list, a differential motion vector (MVD) smaller than the existing method may be encoded and transmitted.

10B shows a motion vector ( A method of setting a first prediction motion vector candidate constituting a prediction motion vector list in the second direction using MV _{L0 ) is shown.} The first prediction motion vector candidate may be obtained by further using reference picture information such as the POC of the reference picture for the first direction and the reference picture for the second direction for the motion vector for the first direction. For example, the reference picture 40b for the first direction of the current block 10 has POC=8, the reference picture 50b for the second direction has POC=12, and the first of the current block 10 When the motion vector MVL0 for the direction is (5,8), as shown in Table 4 below, the first predicted motion vector in the second direction may be (-5,8) scaled based on the POC.

index Prediction motion vector list in the first direction (AMVP_L0) Second direction prediction motion vector list (AMVP_L1) 0 MV_A1 _L0 =(-2,-3) Scaled_MV _L0 =(5,8) One MV_B0 _L0 =(-1,-11) MV_B0 _L1 =(-2,11)

Referring to FIG. 5B together with FIG. 10B, in the first direction to construct a prediction motion vector list (AMVP_L1) in the second direction under the condition that images referenced in each direction are different when the current block 10 is bidirectionally predicted. In the case where motion information must be obtained and configured from neighboring blocks of the current block independently of the motion information of the current block, differential motion information MVD _{L1 in} the second direction to be transmitted may be (6,-1). _{However, when using the scaled motion vector Scaled_MV L0} in the first direction as the first prediction motion vector candidate, the differential motion vector MVD _L1 in the second direction may be (−1,2).

As such, the motion vector MV _L0 for the first direction and the motion vector MV _L1 for the second direction have a high correlation. Therefore, the method of constructing the predicted motion vector list of the present invention that sets the first predicted motion vector (MV _L1 ) in the second direction by scaling the motion vector for the first direction based on the POC (Scaled_MV _{L0 ) is a conventional method.} Since the differential motion vector (MVD _L1 ), which is relatively smaller than the method, can be encoded and transmitted, coding efficiency can be improved. In an embodiment, in order to improve coding efficiency, the first prediction motion vector candidate may have the shortest codeword among indices constituting the prediction motion vector list in the second direction, but the present invention is not limited thereto. Although the present invention discloses a method of scaling a motion vector in the first direction based on POC as a first prediction motion vector candidate in the second direction, the method of scaling is not limited thereto.

11 is a flowchart illustrating a method of constructing a predictive motion vector list according to another embodiment of the present invention. Referring to FIG. 11 , in order to construct the AMVP list of the current block, a motion vector MV _L0 for the first direction is obtained ( S10 ). The motion vector for the first direction may be obtained from a decoder using a predicted motion vector candidate and a differential motion vector of a predicted motion vector list in the first direction received from the encoder, or may be received from an encoder. The method of obtaining the motion vector for the first direction is not limited.

_{Thereafter, it is determined whether picture information (POC ref _L0} ) of the reference picture for the first direction used for bidirectional prediction of the current block and picture information (POC _{ref _L1} ) of the reference picture for the second direction are the same (S30) ). For example, whether the first and second reference pictures are the same may be determined based on picture information such as POC.

If the picture information of the reference picture for the first direction and the reference picture for the second direction is the same (Yes in S30), the first prediction motion vector candidate constituting the prediction motion vector list AMVP_L1 in the second direction A motion vector MV _L0 for the first direction may be set as (MVP_L1_0) (S40). The first predictive motion vector candidate may be at least one predictive motion vector candidate. In addition, at least one second prediction motion vector candidate (MVP_L1_N) constituting the prediction motion vector list in the second direction may be set according to a general method ( S50 ). The first predicted motion vector candidate in the second direction set by copying the motion vector for the first direction, and the acquisition order of the second predicted motion vector candidate in the second direction obtained by a general method and the predicted motion in the second direction When constructing a vector list, an index allocation method is not limited.

If the picture information of the reference picture for the first direction and the reference picture for the second direction are different (No in S30), a first prediction motion vector candidate (MVP_L1_0) constituting the prediction motion vector list in the second direction _{As , a scaled value (Scaled_MV L0} ) of the motion vector for the first direction may be set (S60). The first predictive motion vector candidate may be at least one predictive motion vector candidate. In addition, at least one second prediction motion vector candidate (MVP_L1_N) constituting the prediction motion vector list in the second direction may be set according to a general method ( S70 ). The first predicted motion vector candidate in the second direction set to a scaled value of the motion vector for the first direction, and the second direction prediction motion vector candidate obtained by a general method, and the second direction When constructing a predictive motion vector list, an index allocation method is not limited.

In the AMVP list constructed according to the above method, the motion vector for the first direction with high correlation in inter prediction is used when constructing the predictive motion vector list in the second direction. A method of constructing a vector list may be provided. In addition, in bidirectional prediction, whether picture information of the reference picture for the first direction and the reference picture for the second direction is the same, and any one or more of the distance between the reference pictures and the current picture is taken into consideration in the second direction prediction Coding efficiency may be increased by setting at least one predictive motion vector candidate constituting the motion vector list.

It is common in the art to which the present invention pertains that the present invention described above is not limited to the above-described embodiments and the accompanying drawings, and that various substitutions, modifications, and changes are possible without departing from the technical spirit of the present invention. It will be clear to those who have knowledge.

Claims (15)

obtaining a motion vector for a first direction referring to a first reference picture of a current block; and
At least one prediction motion vector candidate in the second direction constituting a prediction motion vector list in the second direction that refers to a second reference picture of a current block different from the first direction by using the motion vector for the first direction A method of constructing a bidirectional inter-screen prediction motion vector list, comprising the step of setting. The method of claim 1,
The at least one prediction motion vector candidate in the second direction is a method of constructing a bidirectional inter-picture prediction motion vector list in which the motion vectors for the first direction are copied and set. 3. The method of claim 2,
A method of constructing a bidirectional inter prediction motion vector list in which the first reference picture for the first direction and the second reference picture for the second direction have the same picture information. 3. The method of claim 2,
The method of constructing a bidirectional inter prediction motion vector list in which the prediction motion vector candidates of the second direction are allocated to the index in the order of having the smallest codeword. The method of claim 1,
The method of constructing a bidirectional inter-picture predicted motion vector list in which the prediction motion vector candidate in the second direction is set by scaling the motion vector in the first direction based on picture information. 6. The method of claim 5,
A method of constructing a bidirectional inter-picture prediction motion vector list in which picture information of the first reference picture for the first direction and the picture information of the second reference picture for the second direction are different. 6. The method of claim 5,
The method of constructing a bidirectional inter prediction motion vector list in which the prediction motion vector candidates of the second direction are allocated to the index in the order of having the smallest codeword. The method of claim 1,
Before the step of setting the prediction motion vector candidates of the at least one or more second directions,
and determining whether picture information of the first reference picture for the first direction and the picture information for the second reference picture for the second direction is the same. a motion vector obtaining unit which obtains a motion vector for a first direction referring to a first reference picture of a current block; and
At least one prediction motion vector candidate in the second direction constituting a prediction motion vector list in the second direction that refers to a second reference picture of a current block different from the first direction by using the motion vector for the first direction An apparatus for constructing a bidirectional inter-screen prediction motion vector list including a second direction prediction motion vector list setting unit to set. 10. The method of claim 9,
The second direction prediction motion vector list setting unit,
a first predicted motion vector candidate setting unit configured to set at least one predicted motion vector candidate in the second direction by using the motion vector for the first direction; and
and a second prediction motion vector candidate setting unit configured to set at least one prediction motion vector candidate in the second direction using spatial and temporal neighboring blocks of the current block. 11. The method of claim 10,
The apparatus for configuring a bidirectional inter-picture predicted motion vector list in which the predicted motion vector candidate in the second direction obtained by the first predicted motion vector candidate setting unit is set by copying the motion vector in the first direction. 12. The method of claim 11,
An apparatus for constructing a bidirectional inter prediction motion vector list in which picture information of the first reference picture for the first direction and the picture information of the second reference picture for the second direction are the same. 11. The method of claim 10,
The predictive motion vector candidate in the second direction obtained by the first predictive motion vector candidate setting unit is configured by scaling the motion vector in the first direction based on picture information to configure the bidirectional inter-picture predictive motion vector list . 14. The method of claim 13,
An apparatus for constructing a bidirectional inter-picture predicted motion vector list in which picture information of the first reference picture for the first direction and the second reference picture for the second direction are different. 11. The method of claim 10,
The apparatus for constructing a bidirectional inter prediction motion vector list in which the prediction motion vector candidates in the second direction obtained by the first prediction motion vector candidate setting unit are allocated to indices in the order of having the smallest codeword.

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