KR20130008481A - Method for inter prediction and apparatus thereof - Google Patents

Abstract

PURPOSE: An inter prediction method and a device thereof are provided to reduce calculation complexity by performing a motion compensation process when L0 motion information and L1 motion information are same. CONSTITUTION: A motion prediction unit derives motion information of a current block as motion information including L0 motion information and L1 motion information. A motion compensation unit(250) performs motion compensation for the current block based on one or more of the L0 motion information and the L1 motion information. A reconstruction block generating unit generates a reconstruction block corresponding to the current block based on a generated prediction block. [Reference numerals] (210) Entropy decoding unit; (220) Inverse quantization unit; (230) Inverse change unit; (240) Intra prediction unit; (250) Motion compensation unit; (260) Filter unit; (270) Reference picture buffer; (AA) Bit stream; (BB) Intra; (CC) Inter; (DD) Reconstructed image

Description

Inter prediction method and apparatus therefor {METHOD FOR INTER PREDICTION AND APPARATUS THEREOF}

The present invention relates to image processing, and more particularly, to an inter prediction method and an apparatus thereof.

Recently, as the broadcasting service having high definition (HD) resolution has been expanded not only in Korea but also in the world, many users are getting used to high resolution and high quality video, and many organizations are accelerating the development of next generation video equipment. In addition, as interest in Ultra High Definition (UHD), which has four times the resolution of HDTV, is increasing along with HDTV, a compression technology for higher resolution and higher quality images is required.

For image compression, an inter prediction technique for predicting a pixel value included in a current picture from a previous and / or subsequent picture in time, and for predicting a pixel value included in a current picture using pixel information in the current picture. An intra prediction technique, an entropy encoding technique of allocating a short code to a symbol with a high frequency of appearance and a long code to a symbol with a low frequency of appearance may be used.

An object of the present invention is to provide an image encoding method and apparatus for improving image encoding efficiency.

Another object of the present invention is to provide an image decoding method and apparatus for improving image encoding efficiency.

Another technical problem of the present invention is to provide an inter prediction method and apparatus for improving image coding efficiency.

Another technical problem of the present invention is to provide a method and apparatus for deriving motion information capable of improving video encoding efficiency.

Another technical problem of the present invention is to provide a method and apparatus for deriving temporal motion information that can improve image encoding efficiency.

One embodiment of the present invention is a video decoding apparatus. The apparatus may include a motion predictor that derives motion information of a current block as motion information including L0 motion information and L1 motion information, and moves on the current block based on at least one of the L0 motion information and the L1 motion information. By performing the compensation, a motion compensation unit for generating a prediction block corresponding to the current block and a reconstruction block generation unit for generating a reconstruction block corresponding to the current block based on the prediction block, wherein the motion compensation unit, The motion compensation is performed based on whether the L0 motion information and the L1 motion information are identical.

The L0 motion information includes an L0 motion vector and an L0 reference picture number, the L0 reference picture number indicates a picture order count (POC) assigned to an L0 reference picture, and the L1 motion information refers to an L1 motion vector and L1. It includes a picture number, the L1 reference picture number may indicate a POC (Picture Order Count) assigned to the L1 reference picture.

When the L0 motion vector and the L1 motion vector are the same and the L0 reference picture number and the L1 reference picture number are the same, the motion compensator is based on the L0 motion information among the L0 motion information and the L1 motion information. Uni prediction may be performed.

When the L0 motion vector and the L1 motion vector are not identical to each other or the L0 reference picture number and the L1 reference picture number are not equal to each other, the motion compensator is based on the L0 motion information and the L1 motion information. Bi prediction may be performed.

Another embodiment of the present invention is a video decoding apparatus. The apparatus may include a motion predictor that derives motion information of a current block as motion information including L0 motion information and L1 motion information, and moves on the current block based on at least one of the L0 motion information and the L1 motion information. By performing the compensation, a motion compensation unit for generating a prediction block corresponding to the current block and a reconstruction block generation unit for generating a reconstruction block corresponding to the current block based on the prediction block, wherein the motion compensation unit, The motion compensation is performed based on the size of the current block.

When the size of the current block is smaller than a predetermined size, the motion compensator may perform uni prediction based on the L0 motion information among the L0 motion information and the L1 motion information.

The predetermined size may be 8x8.

Another embodiment of the present invention is an image decoding device. The apparatus may include: a motion predictor for deriving motion information from a picture reconstructed already; a motion compensator for generating a prediction block corresponding to a current block based on the derived motion information; And a reconstruction block generation unit configured to generate a corresponding reconstruction block, wherein the motion information includes a motion vector and a reference picture index, wherein the motion predictor sets the reference picture index to 0, and The motion vector is derived based on a call block corresponding to the current block in the reconstructed picture.

The encoding mode of the current block is a merge mode, and the motion compensator selects the temporal motion information as motion information of the current block and performs motion compensation based on the selected motion information, thereby providing the current block. A prediction block corresponding to may be generated.

According to the image encoding method according to the present invention, image encoding efficiency can be improved.

According to the image decoding method according to the present invention, image encoding efficiency can be improved.

According to the inter prediction method according to the present invention, image coding efficiency may be improved.

According to the motion information deriving method according to the present invention, image encoding efficiency may be improved.

According to the method of deriving temporal motion information according to the present invention, image encoding efficiency may be improved.

1 is a block diagram illustrating a configuration of an image encoding apparatus according to an embodiment of the present invention.
2 is a block diagram illustrating a configuration of an image decoding apparatus according to an embodiment of the present invention.
3 is a flowchart schematically illustrating an embodiment of an inter prediction method.
4 is a diagram schematically illustrating an embodiment of an inter prediction method when bidirectional prediction is applied.
5 is a diagram schematically showing an embodiment of motion information of an encoded image.
6 is a flowchart schematically illustrating an embodiment of a method for deriving temporal motion information of a current block according to the present invention.
7 is a diagram schematically illustrating an embodiment of a reconstructed neighboring block used for resetting L1 temporal motion information.
FIG. 8 is a block diagram schematically illustrating an embodiment of an inter prediction apparatus capable of performing a process of deriving temporal motion information according to the embodiment of FIG. 6.
9 is a flowchart schematically showing another embodiment of a method for deriving temporal motion information of a current block according to the present invention.
10 is a diagram schematically showing an embodiment of a second call block used for resetting L1 temporal motion information.
FIG. 11 is a block diagram schematically illustrating an embodiment of an inter prediction apparatus capable of performing a process of deriving temporal motion information according to the embodiment of FIG. 9.
12 is a diagram schematically showing an embodiment of a method for deriving motion information of a current block according to the present invention.
FIG. 13 is a block diagram schematically illustrating an embodiment of an inter prediction apparatus capable of performing a motion information derivation process according to the embodiment of FIG. 12.
14 is a flowchart schematically illustrating still another embodiment of a method for deriving temporal motion information of a current block according to the present invention.
FIG. 15 is a block diagram schematically illustrating an embodiment of an inter prediction apparatus capable of performing a process of deriving temporal motion information according to the embodiment of FIG. 14.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following description of the embodiments of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present disclosure rather unclear.

It is to be understood that when an element is referred to as being "connected" or "connected" to another element, it may be directly connected or connected to the other element, . In addition, the description of "including" a specific configuration in the present invention does not exclude a configuration other than the configuration, and means that additional configurations can be included in the practice of the present invention or the technical scope of the present invention.

The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component.

In addition, the components shown in the embodiments of the present invention are shown independently to represent different characteristic functions, which does not mean that each component is composed of separate hardware or software constituent units. That is, each constituent unit is included in each constituent unit for convenience of explanation, and at least two constituent units of the constituent units may be combined to form one constituent unit, or one constituent unit may be divided into a plurality of constituent units to perform a function. The integrated embodiments and separate embodiments of the components are also included within the scope of the present invention, unless they depart from the essence of the present invention.

In addition, some of the components are not essential components to perform essential functions in the present invention, but may be optional components only to improve performance. The present invention can be implemented only with components essential for realizing the essence of the present invention, except for the components used for the performance improvement, and can be implemented by only including the essential components except the optional components used for performance improvement Are also included in the scope of the present invention.

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

1, the image encoding apparatus 100 includes a motion prediction unit 111, a motion compensation unit 112, an intra prediction unit 120, a switch 115, a subtractor 125, a transform unit 130, A quantization unit 140, an entropy encoding unit 150, an inverse quantization unit 160, an inverse transformation unit 170, an adder 175, a filter unit 180, and a reference picture buffer 190.

The image encoding apparatus 100 may encode an input image in an intra mode or an inter mode and output a bit stream. Intra prediction means intra prediction and inter prediction means inter prediction. In the intra mode, the switch 115 is switched to the intra mode, and in the inter mode, the switch 115 can be switched to the inter mode. The image encoding apparatus 100 may generate a prediction block for an input block of an input image and then encode a residual between the input block and the prediction block.

In the intra mode, the intra prediction unit 120 may generate a prediction block by performing spatial prediction using the pixel value of the already coded block around the current block.

In the inter mode, the motion estimator 111 may obtain a motion vector by finding a region that best matches the input block in the reference image stored in the reference picture buffer 190 during the motion prediction process. have. The motion compensation unit 112 may generate a prediction block by performing motion compensation using a motion vector.

The subtractor 125 may generate a residual block by a difference between the input block and the generated prediction block. The transforming unit 130 may perform a transform on the residual block to output a transform coefficient. The quantization unit 140 may quantize the input transform coefficient according to the quantization parameter to output a quantized coefficient.

The entropy encoder 150 performs entropy encoding based on values (eg, quantized coefficients) calculated in the quantization unit 140 and / or encoding parameter values calculated in the encoding process to perform a bitstream ( bit stream).

When entropy encoding is applied, a small number of bits are allocated to a symbol having a high probability of occurrence, and a large number of bits are allocated to a symbol having a low probability of occurrence, thereby expressing symbols, The size of the column can be reduced. Therefore, the compression performance of the image encoding can be enhanced through the entropy encoding. The entropy encoder 150 may use an encoding method such as exponential golomb, context-adaptive variable length coding (CAVLC), or context-adaptive binary arithmetic coding (CABAC) for entropy encoding.

Since the image encoding apparatus according to the embodiment of FIG. 1 performs inter prediction encoding, that is, inter-frame prediction encoding, the current encoded image needs to be decoded and stored to be used as a reference image. Accordingly, the quantized coefficients are inversely quantized in the inverse quantization unit 160 and inversely transformed in the inverse transformation unit 170. The inverse quantized and inverse transformed coefficients are added to the prediction block through the adder 175 and a reconstruction block is generated.

The reconstruction block passes through the filter unit 180, and the filter unit 180 applies at least one or more of a deblocking filter, a sample adaptive offset (SAO), and an adaptive loop filter (ALF) to the reconstruction block or the reconstruction picture. can do. The filter unit 180 may be referred to as an adaptive in-loop filter. The deblocking filter may remove block distortion and / or blocking artifacts that occur at the boundaries between blocks. The SAO may add a proper offset value to the pixel value to compensate for coding errors. The ALF may perform filtering based on a value obtained by comparing the reconstructed image with the original image, and may be performed only when high efficiency is applied. The reconstructed block that has passed through the filter unit 180 may be stored in the reference picture buffer 190.

2 is a block diagram illustrating a configuration of an image decoding apparatus according to an embodiment of the present invention.

Referring to FIG. 2, the image decoding apparatus 200 may include an entropy decoder 210, an inverse quantizer 220, an inverse transformer 230, an intra predictor 240, a motion compensator 250, and an adder ( 255, a filter unit 260, and a reference picture buffer 270.

The video decoding apparatus 200 receives the bit stream output from the encoder and decodes the video stream into the intra mode or the inter mode, and outputs the reconstructed video, that is, the reconstructed video. In the intra mode, the switch is switched to the intra mode, and in the inter mode, the switch can be switched to the inter mode. The image decoding apparatus 200 may obtain a residual block from the input bitstream, generate a prediction block, and then add the residual block and the prediction block to generate a reconstructed block, that is, a reconstruction block.

The entropy decoding unit 210 may entropy-decode the input bitstream according to a probability distribution to generate symbols including a symbol of a quantized coefficient type. The entropy decoding method is similar to the entropy encoding method described above.

When the entropy decoding method is applied, a small number of bits are assigned to a symbol having a high probability of occurrence, and a large number of bits are assigned to a symbol having a low probability of occurrence, so that the size of a bit string for each symbol is Can be reduced. Therefore, the compression performance of image decoding can be improved through an entropy decoding method.

The quantized coefficient is inversely quantized by the inverse quantizer 220 and inversely transformed by the inverse transformer 230, and as a result of the inverse quantization / inverse transformation of the quantized coefficient, a residual block may be generated.

In the intra mode, the intra predictor 240 may generate a prediction block by performing spatial prediction using pixel values of blocks that are already decoded around the current block. In the inter mode, the motion compensator 250 may generate a predictive block by performing motion compensation using the reference image stored in the motion vector and the reference picture buffer 270.

The residual block and the prediction block may be added through the adder 255, and the added block may pass through the filter unit 260. The filter unit 260 may apply at least one or more of the deblocking filter, SAO, and ALF to the reconstructed block or the reconstructed picture. The filter unit 260 may output a reconstructed image, that is, a reconstructed image. The reconstructed picture may be stored in the reference picture buffer 270 and used for inter prediction.

Hereinafter, a block means a unit of image encoding and decoding. When encoding or decoding an image, an encoding or decoding unit refers to a divided unit when an image is divided and encoded or decoded, and thus, a coding unit (CU), a prediction unit (PU), and a transformation unit (TU). It may be called a Transform Unit, a transform block, or the like. One block may be further divided into smaller sub-blocks. Further, in the present specification, the term "picture" may be replaced with "frame", "field" and / or "slice" depending on the context, and such classification can be easily made by those skilled in the art There will be. For example, P pictures, B pictures, and forward B pictures described below may be replaced with P slices, B slices, and forward B slices according to context.

3 is a flowchart schematically illustrating an embodiment of an inter prediction method.

Referring to FIG. 3, the encoder and the decoder may derive motion information about the current block (S310).

In the inter mode, the encoder and the decoder may derive motion information of the current block and then perform inter prediction and / or motion compensation based on the derived motion information. In this case, the encoder and the decoder may extract motion information of a coll block corresponding to the current block in a neighboring block and / or a coll picture that has already been restored. By using this, the encoding / decoding efficiency can be improved. Here, the reconstructed neighboring block may include a block adjacent to the current block and / or a block located at the outer corner of the current block, which is a block in the current picture reconstructed by decoding and / or decoding. In addition, the encoder and the decoder may determine a predetermined relative position based on a block that exists at the same spatial position as the current block within the call picture, and the determined predetermined relative position (exists at the same spatial position as the current block). The call block can be derived based on the location of the inside and / or outside of the block). Here, for example, the call picture may correspond to one picture among the reference pictures included in the reference picture list.

Meanwhile, the motion information derivation scheme may vary depending on the prediction mode of the current block. Prediction modes applied for inter prediction may include Advanced Motion Vector Predictor (AMVP), merge, and the like.

For example, when an advanced motion vector predictor (AMVP) is applied, the encoder and the decoder may generate a predicted motion vector candidate list using the motion vector of the reconstructed neighboring block and / or the motion vector of the call block. That is, the motion vector of the reconstructed neighboring block and / or the motion vector of the call block may be used as the prediction motion vector candidate. The encoder may transmit a predicted motion vector index indicating an optimal predicted motion vector selected from the predicted motion vector candidates included in the list to the decoder. In this case, the decoder may select the predicted motion vector of the current block among the predicted motion vector candidates included in the predicted motion vector candidate list by using the predicted motion vector index.

The encoder can obtain a motion vector difference (MVD) between the motion vector of the current block and the predictive motion vector, and can encode the same and transmit the same to the decoder. In this case, the decoder may decode the received motion vector difference and derive the motion vector of the current block through the sum of the decoded motion vector difference and the predicted motion vector.

As another example, when merge is applied, the encoder and the decoder may generate the merge candidate list using the motion information of the reconstructed neighboring block and / or the motion information of the call block. That is, the encoder and the decoder may use the motion information of the reconstructed neighboring block and / or the call block as a merge candidate for the current block.

The encoder may select a merge candidate capable of providing an optimal encoding efficiency among the merge candidates included in the merge candidate list as motion information for the current block. In this case, a merge index indicating the selected merge candidate may be included in the bitstream and transmitted to the decoder. The decoder may select one of the merge candidates included in the merge candidate list using the transmitted merge index, and determine the selected merge candidate as motion information of the current block. Therefore, when the merge mode is applied, the motion information of the restored neighboring block and / or the call block may be used as the motion information of the current block.

In the above-described AMVP and merge mode, the motion information of the reconstructed neighboring block and / or the motion information of the call block may be used to derive the motion information of the current block. Hereinafter, in the embodiments described below, the motion information derived from the reconstructed neighboring block is called spatial motion information, and the motion information derived based on the call block is called temporal motion information. For example, a motion vector derived from a reconstructed neighboring block may be referred to as a spatial motion vector, and a motion vector derived based on a call block may be referred to as a temporal motion vector.

Referring to FIG. 3 again, the encoder and the decoder may generate a prediction block of the current block by performing motion compensation on the current block based on the derived motion information (S320). Here, the prediction block may mean a motion compensated block generated as a result of performing motion compensation on the current block. Also, the plurality of motion compensated blocks may constitute one motion compensated image. Therefore, in the embodiments described below, the prediction block may be referred to as a 'motion compensated block' and / or a 'motion compensated image' according to the context, and this division may be easily performed by those skilled in the art. You will be able to.

Meanwhile, a picture on which inter prediction is performed may include a P picture and a B picture. The P picture may refer to a picture in which unidirectional prediction using one reference picture is performed, and the B picture refers to a picture in which forward, reverse or bidirectional prediction using one or more reference pictures may be performed. can do. For example, in the B picture, inter prediction may be performed using one forward reference picture (past picture) and one backward reference picture (future picture). In addition, in the B picture, prediction may be performed using two forward reference pictures, or prediction may be performed using two backward reference pictures.

Here, the reference pictures may be managed by a reference picture list. One reference picture is used in the P picture, and the reference picture may be allocated to reference picture list 0 (L0 or List0). Two reference pictures are used in the B picture, and the two reference pictures may be assigned to the reference picture list 0 and the reference picture list 1 (L1 or List1), respectively. Hereinafter, the L0 reference picture list may have the same meaning as the reference picture list 0, and the L1 reference picture list may have the same meaning as the reference picture list 1.

In general, the forward reference picture may be assigned to the reference picture list 0 and the backward reference picture may be assigned to the reference picture list1. However, the method of allocating the reference picture is not limited thereto, and the forward reference picture may be assigned to the reference picture list 1 and the backward reference picture may be assigned to the reference picture list 0. Hereinafter, a reference picture assigned to reference picture list 0 is referred to as an L0 reference picture, and a reference picture assigned to reference picture list 1 is referred to as an L1 reference picture.

Reference pictures may be assigned to the reference picture list in descending order, generally according to the reference picture number. Here, the reference picture number may mean a number assigned to each reference picture in the order of POC (Picture Order Count), and the POC order may mean a display order and / or a time order of the pictures. For example, two reference pictures having the same reference picture number may correspond to the same reference picture. Reference pictures allocated to the reference picture list may be rearranged by a reference picture list reordering (RPLR) or a memory management control (MMCO) command.

As described above, unidirectional prediction using one L0 reference picture may be performed on a P picture, and forward, reverse, or bidirectional using one L0 reference picture and one L1 reference picture, that is, two reference pictures, in a B picture. Prediction can be performed. Prediction using one reference picture may be called uni-prediction, and prediction using two reference pictures including an L0 reference picture and an L1 reference picture may be called bi-prediction.

Bi-prediction may be used as a concept including all of forward prediction, backward prediction, and bidirectional prediction. However, in the embodiments described below, prediction using two reference pictures (L0 reference picture and L1 reference picture) is referred to as bidirectional prediction. That is, in the following embodiments, bidirectional prediction may mean pair prediction, and may be understood as a concept including both forward, backward, and bidirectional prediction using two reference pictures (L0 reference picture and L1 reference picture). . In addition, forward prediction or backward prediction may be performed even when bi-prediction is performed. However, in the following embodiments, prediction using only one reference picture is referred to as unidirectional prediction. That is, in the embodiments described below, unidirectional prediction may mean uniprediction and should be understood as a concept including only prediction using one reference picture. In addition, information indicating whether unidirectional prediction (uniprediction) or bidirectional prediction (biprediction) is applied to a block on which prediction is performed is referred to as prediction direction information.

4 is a diagram schematically illustrating an embodiment of an inter prediction method when bidirectional prediction is applied.

As described above, the encoder and the decoder may perform bidirectional prediction as well as unidirectional prediction in inter prediction. When bidirectional prediction is applied, each block on which prediction is performed may have two reference pictures (L0 reference picture and L1 reference picture). In this case, each block in which the bidirectional prediction is performed may have two motion information. Here, the motion information may include a reference picture number and a motion vector.

When bidirectional prediction is performed, the encoder and the decoder may select one reference picture from each of reference picture list 0 and reference picture list 1 to use for prediction. That is, two reference pictures including an L0 reference picture and an L1 reference picture may be used for bidirectional prediction. Hereinafter, motion information corresponding to the L0 reference picture is referred to as L0 motion information, and motion information corresponding to the L1 reference picture is referred to as L1 motion information. In addition, motion compensation using the L0 motion information is referred to as L0 motion compensation, and motion compensation using the L1 motion information is referred to as L1 motion compensation.

Referring to FIG. 4, the encoder and the decoder may generate an L0 motion compensated block by performing an L0 motion compensation 410 on a current block by using the L0 motion information and the L0 reference picture list. In addition, the encoder and the decoder may generate the L1 motion compensated block by performing the L1 motion compensation 420 using the L1 motion information and the L1 reference picture list. In this case, the L0 motion compensation 410 and the L1 motion compensation 420 may be independently performed.

The encoder and the decoder may perform a weighted average 430 on the L0 motion compensated block and the L1 motion compensated block to finally generate one motion compensated block. For example, the weighted average 430 may be performed in units of pixels in the L0 motion compensated block and the L1 motion compensated block. In this case, the finally generated one motion compensated block may correspond to the prediction block of the current block.

Hereinafter, motion compensation applied at the time of bidirectional prediction is referred to as bidirectional motion compensation. Correspondingly, the motion compensation applied in the unidirectional prediction may be referred to as unidirectional motion compensation.

5 is a diagram schematically showing an embodiment of motion information of an encoded image. 5 illustrates a plurality of blocks constituting an encoded image and motion information of each of the plurality of blocks.

The video encoded in FIG. 5 corresponds to BasketballDrill. Here, BasketballDrill represents the name of a test sequence used for an image encoding / decoding experiment. The encoded image has a size of 832x480 and a POC (Picture Order Count) of 2. In addition, the quantization parameter (QP) value applied to the image of FIG. 5 is 32.

The encoder and the decoder may use a forward B picture to improve inter prediction efficiency in a low delay application environment. Here, the forward B picture may mean a B picture in which only forward prediction is performed. When a forward B picture is used, each block in which prediction is performed may have two motion information (L0 motion information and L1 motion information). In the forward B picture, in general, the L0 reference picture list and the L1 reference picture list may be set identically. Hereinafter, in the present specification, it is assumed that the L0 reference picture list and the L1 reference picture list are the same when a forward B picture is used.

The decoder may directly determine whether the current picture is a forward B picture based on the L0 reference picture list and the L1 reference picture list, or may determine whether the current picture is a forward B picture based on information transmitted from the encoder. have. For example, the encoder may encode a flag indicating whether the L0 reference picture list and the L1 reference picture list are the same and transmit the same to the decoder. In this case, the decoder may receive and decode the flag, and then determine whether the current picture is a forward B picture based on the decoded flag. As another example, the encoder may transmit a NAL unit type value or slice type value corresponding to the forward B picture to the decoder, and the decoder may determine whether the forward B picture is based on the received value.

The image shown in FIG. 5 is an image encoded using a forward B picture. Therefore, each block in the encoded image may have up to two motion information. In this case, the motion information may include a reference picture number, a motion vector, and the like. Referring to FIG. 5, a block having the same L0 motion information (eg, reference picture number and motion vector) and L1 motion information (eg, reference picture number and motion vector) among blocks having two motion information. There may be multiple.

A block having the same L0 motion information (eg, reference picture number and motion vector) and L1 motion information (eg, reference picture number and motion vector) in a forward B picture may occur due to a method of deriving temporal motion information. have. As described above, the temporal motion information may be derived from the motion information of the call block corresponding to the current block in the already restored call picture. For example, when deriving the L0 temporal motion information of the current block, the encoder and the decoder may use the L0 motion information of the call block corresponding to the current block in the call picture. However, when there is no L0 motion information in the call block, the encoder and the decoder may use the L1 motion information of the call block as the L0 temporal motion information of the current block. Conversely, when deriving L1 temporal motion information of the current block, the encoder and decoder may use the L1 motion information of the call block corresponding to the current block in the call picture. However, when L1 motion information does not exist in the call block, the encoder and the decoder may use the L0 motion information of the call block as the L1 temporal motion information of the current block. As a result of the above-described process, a phenomenon may occur in which the L0 motion information and the L1 motion information of the current block are the same. Accordingly, in the present specification, when L0 motion information (eg, reference picture number and motion vector) and L1 motion information (eg, reference picture number and motion vector) are the same, and / or L0 temporal motion information (eg, For example, when the reference picture number and the motion vector) and the L1 temporal motion information (for example, the reference picture number and the motion vector) are the same, the motion information of the call block corresponding to the current block is L0 in the call picture that has already been restored. It may include a case having only one of the motion information and the L1 motion information.

In addition, when a block having the same L0 motion information and L1 motion information is generated, the block may affect a block to be encoded later. For example, when merge is applied, the motion information (L0 motion information and L1 motion information) of the restored neighboring block and / or the call block may be used as the motion information of the current block. Therefore, when a block having the same L0 motion information and L1 motion information is generated, more other blocks having the same L0 motion information and L1 motion information may be generated.

When motion compensation is performed on a block in which the L0 motion information and the L1 motion information are the same, the same process may be repeatedly performed twice in one block. Since this is very inefficient from an encoding point of view, an inter prediction method and / or a motion compensation method capable of solving the above-described problems, reducing computational complexity and improving encoding efficiency may be provided. For example, when the L0 motion information (eg, reference picture number and motion vector) and the L1 motion information (eg, reference picture number and motion vector) are the same, the encoder and decoder perform the motion compensation process only once. The computational complexity can be reduced. As another example, when the L0 motion information (eg, reference picture number and motion vector) and the L1 motion information (eg, reference picture number and motion vector) are the same, the encoder and decoder may perform L0 motion information and / or L1 motion. It is also possible to increase the coding efficiency by resetting the information.

6 is a flowchart schematically illustrating an embodiment of a method for deriving temporal motion information of a current block according to the present invention.

Embodiments described below are described based on temporal motion information, but the present invention is not limited thereto. For example, the methods according to the embodiment of FIG. 6 may be used in the motion information and / or the AMVP mode of the current block derived based on the merge candidate list in the merge mode as well as the temporal motion information in the merge mode and / or the AMVP mode. The same may be applied to the motion information of the current block derived based on the predicted motion vector candidate list in the same or similar manner.

As described above, the temporal motion information may be derived based on the motion information of the call block corresponding to the current block in the call picture that has already been restored. Here, the call picture may correspond to one picture from among reference pictures included in the reference picture list. The encoder and the decoder may determine a predetermined relative position with respect to a block existing at a position spatially identical to the current block in the call picture, and determine the predetermined relative position (eg, the same as the current block spatially). The call block may be derived based on a location inside and / or outside a block existing at a location. The temporal motion information derived based on the call block may include prediction direction information, an L0 reference picture number, an L1 reference picture number, an L0 motion vector, an L1 motion vector, and the like.

Referring to FIG. 6, the encoder and the decoder determine whether L0 temporal motion information and L1 temporal motion information are the same in temporal motion information derived based on a call block, that is, the L0 reference picture number and the L1 reference picture number are the same and the L0 motion is the same. It may be determined whether the vector and the L1 motion vector are the same (S610).

If the L0 temporal motion information and the L1 temporal motion information are not the same, that is, if the L0 reference picture number and the L1 reference picture number are not the same and / or the L0 motion vector and the L1 motion vector are not the same, the encoder and the decoder call. The temporal motion information derived based on the block may be used as temporal motion information on the current block as it is. When AMVP is applied, temporal motion information of the current block may be determined or registered as a predictive motion vector candidate for the current block. In addition, when merge is applied, temporal motion information of the current block may be determined or registered as a merge candidate for the current block.

If the L0 temporal motion information and the L1 temporal motion information are the same, the encoder and the decoder may determine whether the motion information of the reconstructed neighboring block exists or not (S620). For example, at this time, the encoder and the decoder may determine whether a block having motion information exists among the reconstructed neighboring blocks at the predetermined position and / or the position selected by the predetermined method. Here, the reconstructed neighboring block may include a block adjacent to the current block and / or a block located at the outer corner of the current block, which is a block in the current picture reconstructed by decoding and / or decoding.

If the motion information of the reconstructed neighboring block does not exist (e.g., when there is no block having the motion information among the reconstructed neighboring blocks of the predetermined position and / or the selected position by the predetermined method), the encoder and the decoding. The device may reset the prediction direction information of the current block to unidirectional prediction (S630). In this case, the encoder and the decoder may use only L0 temporal motion information as temporal motion information of the current block.

If there is motion information of the reconstructed neighboring block (for example, if there is a block with motion information among the reconstructed neighboring blocks of the predetermined position and / or the position selected by the predetermined method), the encoder and the decoder may The reconstructed motion information of the neighboring block may be used as L1 temporal motion information of the current block (S640). That is, at this time, the encoder and the decoder may reset the L1 temporal motion information of the current block to the motion information of the reconstructed neighboring block. A specific embodiment of the reconstructed neighboring block used for setting the L1 temporal motion information will be described later.

In the above-described embodiment, the method of deriving temporal motion information of the current block is described based on a flowchart as a series of steps, but one or more steps of the flowchart may be deleted. For example, the steps of S620 and S640 may be omitted in the above-described embodiment. At this time, when the L0 temporal motion information and the L1 temporal motion information are the same, the encoder and the decoder may set the prediction direction information of the current block to unidirectional prediction (S630). In this case, the encoder and the decoder may use only L0 temporal motion information as temporal motion information of the current block.

Meanwhile, in the above-described embodiment, whether to perform the processes S620 to S640 is determined based on the sameness of the L0 temporal motion information and the L1 temporal motion information, but the encoder and the decoder determine whether to perform the processes S620 to S640 based on other conditions. It may be.

In an embodiment, the encoder and the decoder may determine whether to perform the processes S620 to S640 based on the identity of the L0 reference picture number and the L1 reference picture number in the temporal motion information derived based on the call block. For example, the encoder and the decoder may perform processes S620 to S640 when the L0 reference picture number and the L1 reference picture number are the same.

In another embodiment, the encoder and the decoder may determine whether to perform the processes S620 to S640 based on the prediction direction of the call block. As described above, the prediction direction information may mean information indicating whether unidirectional prediction or bidirectional prediction is applied to a block on which prediction is performed. Therefore, the prediction direction may correspond to unidirectional prediction or bidirectional prediction. For example, the encoder and the decoder may perform processes S620 to S640 when the motion information (prediction direction) of the call block is unidirectional prediction instead of bidirectional prediction. This is because, when the prediction direction of the call block is unidirectional prediction, L0 temporal motion information and L1 temporal motion information may be the same in temporal motion information derived based on the call block.

In another embodiment, the encoder and the decoder may determine whether to perform the processes S620 to S640 based on information on whether motion information exists in the call block. For example, the encoder and the decoder may perform processes S620 to S640 when motion information does not exist in the call block. In this case, in step S640 described above, the L0 temporal motion information may be reset instead of the L1 temporal motion information. That is, the encoder and the decoder may set the L0 temporal motion information as the motion information of the reconstructed neighboring block, and may perform unidirectional prediction instead of bidirectional prediction on the current block. In addition, when there is no motion information in the call block, in step S640, the encoder and the decoder may reset both the L0 temporal motion information and the L1 temporal motion information. That is, the encoder and the decoder may set L0 temporal motion information and L1 temporal motion information as motion information of the reconstructed neighboring block, and may perform bidirectional prediction on the current block.

In another embodiment, the encoder and the decoder may determine whether to perform the processes S620 to S640 based on the size of the current block. As an example, the encoder and the decoder may determine whether the size of the current block is smaller than a predetermined size. Here, the current block may be a CU, a PU, and / or a TU, and the predetermined size may be, for example, one of 8x8, 16x16, or 32x32. In this case, the encoder and the decoder may perform processes S620 to S640 when the size of the current block is smaller than the predetermined size.

In another embodiment, the encoder and the decoder may perform processes S620 to S640 when the L0 motion vector and / or the L1 motion vector corresponds to the zero vector (0,0) in the motion information of the call block. In this case, in step S640, the encoder and the decoder may reset the motion vector (s) corresponding to the zero vector (0, 0). For example, the motion vector (s) corresponding to the zero vector (0,0) may be set as a motion vector of the reconstructed neighboring block. As another example, the motion vector (0) corresponds to the zero vector (0,0). May be set to a motion vector of a block located around the call block. In another embodiment, the encoder and the decoder may perform processes S620 to S640 when the L0 motion vector and / or the L1 motion vector do not correspond to the zero vector (0,0) in the motion information of the call block. In this case, in step S640, the encoder and the decoder may reset the motion vector (s) not corresponding to the zero vector (0,0), and the motion vector (s) not corresponding to the zero vector (0,0). ) May be reset to the motion vector of the reconstructed neighboring block.

Conditions for determining whether to perform the processes S620 to S640 are not limited to the above-described embodiment, and various conditions may be applied according to conditions and / or needs.

On the other hand, when AMVP is applied, the encoder and / or decoder may use the candidate having the least difference from the motion vector of the current block among the prediction motion vector candidates in the prediction motion vector candidate list as the prediction motion vector of the current block, and merge is applied. In this case, the encoder and / or decoder may use a merge candidate capable of providing optimal encoding efficiency among the merge candidates in the merge candidate list as motion information for the current block. Since the predicted motion vector candidate list and the merge candidate list may each contain temporal motion information and / or spatial motion information, as a result, motion information (eg, reference picture number, motion information, etc.) of the current block may be restored. Can be derived based on the motion information of the block. Therefore, in the above-described L1 temporal motion information resetting step (S640), the encoder and the decoder may reset the L1 temporal motion information based on the predicted motion vector candidate list of the current block and / or the merge candidate list of the current block. In this case, the step (S630) of determining whether the above-described restored neighboring block is present may be omitted. Hereinafter, in the following embodiments, the motion information candidate list may be understood as a concept including a predicted motion vector candidate list and a merge candidate list.

As described above, the encoder and the decoder may reset the L1 temporal motion information of the current block based on the motion information candidate list of the current block. That is, the encoder and the decoder may use one of the motion information candidates included in the motion information candidate list of the current block as L1 temporal motion information. The motion information used as the L1 temporal motion information in the motion information candidate list of the current block may be determined in various ways.

In an embodiment, the encoder and the decoder may search for motion information candidates in the motion information candidate list in order from the first motion information candidate to the last motion information candidate. In this case, the encoder and the decoder may use the first motion information candidate having the same reference picture number as the L1 reference picture number of the L1 temporal motion information derived based on the call block as the L1 temporal motion information of the current block. In this case, the encoder and the decoder may use the L0 motion information of the first motion information candidate having the same reference picture number as the L1 reference picture number, and the first motion information candidate having the same reference picture number as the L1 reference picture number. L1 motion information may also be used. Meanwhile, motion information having the same reference picture number as the L1 reference picture number of the L1 temporal motion information derived based on the call block may not exist in the motion information candidate list. In this case, the encoder and the decoder may add motion information having the same reference picture number as the L1 reference picture number among the motion information of the reconstructed neighboring block to the motion information candidate list. In this case, the encoder and the decoder may reset the L1 temporal motion information of the current block based on the motion information candidate list to which the motion information of the reconstructed neighboring block is added.

In another embodiment, the encoder and the decoder may use the motion vector of the first motion information candidate having the available motion vector in the motion information candidate list as the L1 temporal motion information of the current block. In this case, the encoder and the decoder may use the L0 motion information of the first motion information candidate or may use the L1 motion information of the first motion information candidate.

In another embodiment, the encoder and the decoder may use the first motion information candidate available in the motion information candidate list as the L1 temporal motion information of the current block. In this case, the L1 reference picture number of the L1 temporal motion information is changed or set to the reference picture number of the first motion information candidate, and the L1 motion vector of the L1 temporal motion information is changed to the motion vector of the first motion information candidate. Can be set. In this case, the encoder and the decoder may use the L0 motion information of the first motion information candidate or may use the L1 motion information of the first motion information candidate.

The method for determining the motion information candidate used as the L1 temporal motion information in the motion information candidate list of the current block is not limited to the above-described embodiment, and various conditions may be applied according to conditions and / or needs.

In the above embodiments, there may be no motion information available in the motion information candidate list of the current block. In this case, as an example, the encoder and the decoder may use the reconstructed motion information of the neighboring block as the L1 temporal motion information of the current block as in step S640. As another example, in this case, the encoder and the decoder may add motion information of the reconstructed neighboring block to the motion information candidate list, and may add a zero vector (0, 0) to the motion information candidate list. At this time, the encoder and the decoder may reset the L1 temporal motion information of the current block based on the motion information candidate list to which the motion information of the reconstructed neighboring block is added or the motion information candidate list to which the zero vector (0, 0) is added. have.

In the above-described embodiments, since the L0 temporal motion information and the L1 temporal motion information are motion information derived in time, the L0 temporal motion information is likely to correspond to motion information due to movement of an object. Therefore, when the encoder and the decoder search for motion information to be used as L1 temporal motion information of the current block in the reconstructed neighboring block and / or motion information candidate list, the motion information having a zero vector (0,0) is not selected and is zero. It is also possible to select motion information that does not have a vector (0, 0). This is because a block having motion information corresponding to a zero vector (0, 0) is likely to correspond to a background rather than an object.

Meanwhile, the reset L1 temporal motion information may be the same as the L0 temporal motion information of the current block. Accordingly, the encoder and the decoder may select motion information that is not the same as L0 temporal motion information when searching for motion information to be used as L1 temporal motion information of the current block in the reconstructed neighboring block and / or motion information candidate list. For example, as in S640 described above, when the L1 temporal motion information of the current block is derived based on the reconstructed neighboring block, the encoder and the decoder identify a block having motion information different from the L0 temporal motion information of the current block. L1 may be determined as a block used for deriving temporal motion information. In this case, the encoder and the decoder may select only the motion information whose difference from the L0 temporal motion information of the current block is less than or equal to a predetermined threshold as the motion information to be used as the L1 temporal motion information of the current block. The predetermined threshold value may be determined based on mode information of the current block, motion information of the current block, mode information of a neighboring block, and / or motion information of a neighboring block, and may be determined in various ways.

In addition, in the above-described embodiments, the motion information selected from the motion information and the motion information candidate list of the reconstructed neighboring block may include both L0 motion information and L1 motion information, respectively. In this case, the encoder and the decoder may determine one piece of motion information from the L0 motion information and the L1 motion information as the motion information to be used as the L1 temporal motion information of the current block. For example, the encoder and the decoder may use the L0 motion information as the L1 temporal motion information of the current block in the motion information selected from the reconstructed neighboring block and / or the motion information candidate list. In this case, when the L0 motion information does not exist in the motion information and / or the motion information candidate list selected from the reconstructed neighboring block, the encoder and the decoder may use the L1 motion information as the L1 temporal motion information of the current block. . As another example, the encoder and the decoder may use the L1 motion information as the L1 temporal motion information of the current block in the motion information selected from the reconstructed neighboring block and / or the motion information candidate list. In this case, when the L1 motion information does not exist in the motion information and / or the motion information candidate list selected from the reconstructed neighboring block, the encoder and the decoder may use the L0 motion information as the L1 temporal motion information of the current block. .

Meanwhile, the encoder and the decoder may not use the reconstructed neighboring block motion information and / or motion information candidate list in order to reset the L1 temporal motion information (eg, the L1 motion vector) of the current block in step S640. It may be. In this case, the encoder and the decoder may reset the L1 temporal motion information (eg, L1 motion vector) of the current block based on the L0 temporal motion information (eg, L0 motion vector) of the current block. Hereinafter, related embodiments will be described, which will be described with reference to a motion vector.

In one embodiment, the encoder and the decoder is L1 of the current block to the motion information indicating the relative position moved based on a predetermined distance and / or direction from the location indicated by the L0 temporal motion information (L0 motion vector) of the current block It can be used as temporal motion information (L1 motion vector). In one example, the encoder and decoder may be one-fourth the size (e.g., (-1,0), (1,0), ( 0, -1), (0,1), (-1, -1), (-1,1), (1, -1), (1,1), etc., where 1/4 pixel units are 1 Motion information indicating the moved position can be used as L1 temporal motion information of the current block. As another example, the encoder and the decoder may have a size of 1/2 pixel in the vertical and / or horizontal direction (eg, (-2,0), (2,0), ( 0, -2), (0,2), (-2, -2), (-2,2), (2, -2), (2,2), etc. where 1/4 pixel units are 1 Motion information indicating the moved position can be used as L1 temporal motion information of the current block. As another example, the encoder and the decoder may have integer pixel sizes (eg, (-4,0), (4,0), (0) in the vertical and / or horizontal directions at positions indicated by the L0 temporal motion information of the current block. , -4), (0,4), (-4, -4), (-4,4), (4, -4), (4,4), etc. where 1/4 pixel units are The motion information indicating the moved position may be used as L1 temporal motion information of the current block. On the other hand, since the motion vector includes a vertical component and a horizontal component, the above-described methods (move by 1/4 pixel size, move by 1/2 pixel size, and move by integer pixel size) are the horizontal component and the vertical direction. Each of the components may be applied independently. In this case, the moving distance in the horizontal direction and the moving distance in the vertical direction may be different from each other.

In another embodiment, the encoder and the decoder change the value of L0 temporal motion information (L0 motion vector) of the current block to a value in other pixel units and use the changed value as L1 temporal motion information (L1 motion vector) of the current block. Can be. For example, when the value of the L0 temporal motion information of the current block is a value of 1/4 pixel unit, the encoder and the decoder may change the value of the L0 temporal motion information to a value of 1/2 pixel unit based on a shift operation. The changed value may be used as L1 temporal motion information of the current block. As another example, when the value of the L0 temporal motion information of the current block is a value of 1/2 pixel unit, the encoder and the decoder may change the value of the L0 temporal motion information to an integer pixel unit based on a shift operation. The changed value may be used as L1 temporal motion information of the current block.

The method of resetting the L1 temporal motion information (eg, L1 motion vector) of the current block based on the L0 temporal motion information (eg, L0 motion vector) of the current block is not limited to the above-described embodiment. And / or may be applied in various forms as needed.

Meanwhile, in the above-described embodiment, the temporal motion information input in step S610 before resetting temporal motion information may include not only a motion vector but also a reference picture index. Here, the L0 motion vector and the L1 motion vector may be motion vectors derived temporally based on the call block as described above, and the L0 reference picture index and the L1 reference picture index are reference pictures derived spatially from the reconstructed neighboring block. It may be an index. In this case, the L0 reference picture index and the L1 reference picture index may be set to the smallest non-negative value of the reference picture index of the reconstructed neighboring block. Meanwhile, as another example, the L0 input reference picture index and the L1 input reference picture index may be set to 0 regardless of the motion information of the reconstructed neighboring block.

When the L1 motion vector of the L1 temporal motion information is reset based on the reconstructed neighboring block, the resetting process may also be performed on the L1 reference picture index of the L1 temporal motion information.

Hereinafter, for convenience of explanation, the temporal motion information input in step S610 before resetting temporal motion information is referred to as temporal motion information (L0 input temporal motion information and L1 input temporal motion information). . In addition, the motion vector included in the input temporal motion information is an input motion vector (L0 input motion vector, L1 input motion vector), and the reference picture index included in the input temporal motion information is an input reference picture index (L0 input reference picture index, L1 input). The reference picture index) and the reference picture number included in the input temporal motion information are referred to as an input reference picture number (L0 input reference picture number and L1 input reference picture number).

As described above, when the L1 input motion vector is reset, the encoder and the decoder may also perform a reset process on the L1 input reference picture index. Hereinafter, embodiments of a resetting process for the L1 input reference picture index are described.

In an embodiment, the encoder and the decoder may reset the L1 input reference picture index based on the reconstructed neighboring block. As described above, the encoder and the decoder may use the reconstructed motion information of the neighboring block as L1 temporal motion information of the current block. In this case, the encoder and the decoder may derive the final L1 reference picture index by resetting the L1 input reference picture index to the reference picture index of the reconstructed neighboring block. In another embodiment, the encoder and the decoder may derive the final L1 reference picture index by resetting the L1 input reference picture index value to a predetermined fixed reference picture index value.

In another embodiment, L0 input temporal motion information (eg, L0 input motion vector, L0 input reference picture index, etc.) and L1 input temporal motion information (eg, L1 input motion vector, L1 input reference picture index, etc.) ), The encoder and the decoder may reset both the L0 input reference picture index and the L1 input reference picture index to a value of 0 to use the final temporal motion information. This is because when the L0 input temporal motion information and the L1 input temporal motion information are the same, there is a high probability that both the L0 reference picture index and the L1 reference picture index are both zero.

In another embodiment, the encoder and the decoder may reset the L1 input reference picture index to the same value as the L0 input reference picture index. In contrast, the encoder and the decoder may reset the L1 input reference picture index value to a reference picture index value that is not the same as the L0 input reference picture index. For example, a reference picture index that is not the same as the L0 input reference picture index may exist among the reference picture indexes of the reconstructed neighboring block. In this case, for example, the encoder and the decoder may use the reference picture index most frequently used among the reference picture indices that are not the same as the L0 input reference picture index to reset the L1 input reference picture index. As another example, the encoder and the decoder may use the reference picture index having the smallest non-negative value among the reference picture indexes that are not the same as the L0 input reference picture index to reset the L1 input reference picture index.

Meanwhile, as described above, the encoder and the decoder may derive the final L1 temporal motion vector by resetting the L1 input motion vector value to the same value as the motion vector of the reconstructed neighboring block in the L1 input temporal motion information. In this case, the motion vector of the reconstructed neighboring block may be scaled and used according to an L1 input reference picture index and / or a reset L1 reference picture index. In the L1 input temporal motion information, the L1 input reference picture index may be used as final L1 temporal motion information without resetting, or may be used as final L1 temporal motion information after resetting as in the above-described embodiment. In this case, the reference picture corresponding to the reconstructed motion vector of the neighboring block and the reference picture indicated by the last L1 reference picture index may be different from each other. In this case, the encoder and the decoder may perform scaling on the motion vector of the reconstructed neighboring block and use the scaled motion vector as the final L1 temporal motion information of the current block.

The above-described embodiments may be combined and applied in various ways according to the resetting process of the motion vector and the resetting process of the reference picture index (eg, RefIdxLX, X = 0, 1). In the following embodiments, it is assumed that the L1 input motion vector is reset based on the reconstructed neighboring block. That is, it is assumed that the encoder and the decoder reset the L1 input motion vector to one of the motion vectors of the reconstructed neighboring block.

In an embodiment, the encoder and the decoder may use only the motion vector, not the zero vector (0,0), among the motion vectors of the reconstructed neighboring block to reset the L1 input motion vector. In this case, as an example, the L1 input reference picture index may be used as final L1 temporal motion information without resetting. As another example, the L1 input reference picture index value may be reset to the reference picture index value of the reconstructed neighboring block, and the reset reference picture index may be used as the final L1 temporal motion information. As another example, the L1 input reference picture index value may be reset to a predetermined fixed reference picture index value. Specific embodiments of each of these have been described above, and thus will be omitted here.

In another embodiment, the encoder and the decoder may scale and use the motion vector of the reconstructed neighboring block to reset the L1 input motion vector. In this case, the scaled motion vector may be used as final L1 temporal motion information. In this case, as an example, the L1 input reference picture index may be used as final L1 temporal motion information without resetting. As another example, the L1 input reference picture index value may be reset to the reference picture index value of the reconstructed neighboring block, and the reset reference picture index may be used as the final L1 temporal motion information. As another example, the L1 input reference picture index value may be reset to a predetermined fixed reference picture index value. Specific embodiments of each of these have been described above, and thus will be omitted here.

In another embodiment, the encoder and the decoder are configured to reset only the L1 input motion vector. Only the motion vector having a difference from the L0 temporal motion information (L0 motion vector) of the current block among the reconstructed neighboring blocks is less than or equal to a predetermined threshold value. Can be used. In this case, the encoder and the decoder may use only a motion vector that is not the same as the L0 temporal motion information (L0 motion vector) of the current block among the reconstructed neighboring motion vectors. In this case, as an example, the L1 input reference picture index may be used as final L1 temporal motion information without resetting. As another example, the L1 input reference picture index value may be reset to the reference picture index value of the reconstructed neighboring block, and the reset reference picture index may be used as the final L1 temporal motion information. As another example, the L1 input reference picture index value may be reset to a predetermined fixed reference picture index value. Specific embodiments of each of these have been described above, and thus will be omitted here.

Combinations of the embodiments of the process of resetting the motion vector and the process of resetting the reference picture index are not limited to the above-described embodiment, and various types of combinations as well as the above-described embodiments may be provided as required. have.

Meanwhile, the L1 temporal motion information reset as described above may be the same as the L0 temporal motion information of the current block. Therefore, when the reset L1 temporal motion information is the same as the L0 temporal motion information of the current block, the encoder and the decoder may set the prediction direction information of the current block to unidirectional prediction. In this case, the encoder and the decoder may use only L0 temporal motion information as temporal motion information of the current block. Such a method can be applied to the present invention in combination with the embodiments described above.

7 is a diagram schematically illustrating an embodiment of a reconstructed neighboring block used for resetting L1 temporal motion information. In FIG. 7, block 710 represents the current block (X).

As described above, the reconstructed neighboring block is a block in the current picture that is already encoded and / or decoded and reconstructed, and may include a block adjacent to the current block 710 and / or a block located at an outer corner of the current block. In the embodiment of FIG. 7, the block located at the lower left corner outside the current block 710 is referred to as the lower left corner block A, and the block located at the upper left corner outside the current block 710 is the upper left corner block E. The block located in the upper right corner outside the current block 710 is referred to as the upper right corner block (C). In addition, the block located at the top of the block adjacent to the left of the current block 710 is the uppermost block (F) on the left side, and the block located at the bottom of the block adjacent to the left of the current block 710 is the left lowermost block (A), the current block ( 710) The leftmost block among the blocks adjacent to the top is referred to as the upper leftmost block G, and the rightmost block among blocks adjacent to the top of the current block 710 is referred to as the upper rightmost block B.

As described above in the embodiment of FIG. 6, the encoder and the decoder may use the motion information of the neighboring block reconstructed according to a predetermined condition as the L1 temporal motion information of the current block. That is, the encoder and the decoder may reset the L1 temporal motion information value of the current block to the motion information value of the reconstructed neighboring block. In this case, the motion information used as the L1 temporal motion information of the current block may be derived in various ways.

In an embodiment, the encoder and the decoder may derive the motion information used as the L1 temporal motion information from one block existing at a predetermined position among the reconstructed neighboring blocks. At this time, the block of the predetermined position is the lower left block (A), the upper rightmost block (B), the upper right corner block (C), the lower left corner block (D), the upper left corner block (E), the left side It may correspond to one of the uppermost block F and the upper leftmost block G.

In another embodiment, the encoder and the decoder may scan a plurality of blocks existing at a predetermined position among the reconstructed neighboring blocks in a predetermined order. In this case, the encoder and the decoder may use the motion information of the first block in which the motion information exists in the scan order as the L1 temporal motion information of the current block. The scan target block and the scan order may be determined in various forms. For example, the encoder and the decoder may scan the neighboring blocks in the order of the left top block F, the top leftmost block B, and the top rightmost block B. As another example, the encoder and decoder determine the neighboring blocks in the order of the top left block (F), the top leftmost block (G), the top right corner block (C), the bottom left corner block (D), and the top left corner block (E). You can also scan. As another example, the encoder and the decoder may scan the neighboring blocks in the order of the left lowermost block (A), the upper rightmost block (B), and the upper left corner block (E). As another example, the encoder and the decoder may include neighboring blocks in the order of the lower left block (A), the upper rightmost block (B), the upper right corner block (C), the lower left corner block (D), and the upper left corner block (E). You can also scan As another example, the encoder and the decoder may include a lower left block (A), an upper rightmost block (B), an upper right corner block (C), a lower left corner block (D), an upper left corner block (E), and a left uppermost block ( The neighboring blocks may be scanned in the order F) and the upper leftmost block G.

In another embodiment, the encoder and the decoder may derive an intermediate value for the motion information of a plurality of blocks existing at a predetermined position among the reconstructed neighboring blocks, and use the derived intermediate value as the L1 temporal motion information of the current block. Can be used as For example, the plurality of blocks may be a left uppermost block (F), an upper leftmost block (G), an upper right corner block (C), a lower left corner block (D), and an upper left corner block (E). .

The method for deriving the L1 temporal motion information of the current block from the reconstructed neighboring block is not limited to the above-described embodiment, and the L1 temporal motion information of the current block may be derived in various ways depending on implementation and / or need.

Hereinafter, an embodiment of a process of deriving temporal motion information according to the embodiment of FIGS. 6 and 7 will be described in terms of a decoder.

The input for the temporal motion information derivation process may include a position (xP, yP) of the leftmost sample of the current block, an input motion vector (mvLXCol), and an input reference picture number (RefPicOrder (currPic, refIdxLX, LX)). have. Here, currPic may mean the current picture. The output of the process may be a motion vector (mvLXCol) used as final temporal motion information and information indicating the presence or absence of final temporal motion information (availableFlagLXCol). Here, X may have a value of 0 or 1. For example, when X is 0, mvLXCol, refIdxLX, and LX may represent mvL0Col, refIdxL0, and L0, which may mean variables related to L0 temporal motion information. In addition, mvLX may represent a motion vector, mvLX [0] may mean a motion vector of x component, and mvLX [1] may mean a motion vector of y component. refIdxLX may indicate an LX reference picture index indicating a reference picture in the LX reference picture list in which the reference pictures are stored. If the refIdxLX value is 0, refIdxLX may indicate the first reference picture in the LX reference picture list, and if the refIdxLX value is −1, refIdxLX may indicate that no reference picture exists in the reference picture list. In addition, predFlagLX, which will be described later, may indicate whether motion compensation is performed when generating a prediction block. For example, when the predFlagLX value is 1, the encoder and the decoder may perform motion compensation when generating the prediction block.

If the input motion vectors mvL0Col and mvL1Col are the same, and RefPicOrder (currPic, refIdxL0, L0) and RefPicOrder (currPic, refIdxL1, L1) are the same (i.e., L0 reference picture number and L1 reference picture number are the same), The decoder may perform the following process.

If there is a left uppermost block (A (xP-1, yP)) adjacent to the left of the current block, the left uppermost block is not a block encoded in intra mode, and predFlagL0A is '1' and mvL0A is (0, If not 0), the encoder and the decoder may perform the following process. Here, A may indicate that predFlagL0A and mvL0A are information about the left uppermost block A.

mvL1Col = mvL0A

Otherwise, if there is a top leftmost block (B (xP, yP-1)) adjacent to the top of the current block, and the top leftmost block is not an intra coded block, predFlagL0B is '1' and mvL0B If is not (0,0), the encoder and the decoder may perform the following process. Here, B may indicate that predFlagL0B and mvL0B are information about the leftmost block B. FIG.

mvL1Col = mvL0B

Otherwise, if there is an upper left corner block (E (xP-1, yP-1)) located in the upper left corner outside the current block, the upper leftmost block is not an intra coded block, and predFlagL0E is If '1' and mvL0E is not (0,0), the encoder and the decoder may perform the following process. Here, E may indicate that predFlagL0E and mvL0E are information about the left uppermost block E.

mvL1Col = mvL0E

At this time, if mvL0Col and mvL1Col are the same, the encoder and the decoder may perform the following process.

avilableFlagL1Col = 0

In addition, the encoder and the decoder may perform the following process.

availableFlagCol = availableFlagL0Col || availableFlagL1Col

predFlagLXCol = availableFlagLXCol

Here, availableFlagCol may indicate whether temporal motion information is derived, and predFlagLXCol may indicate whether there is final temporal motion information for each of L0 temporal motion information and L1 temporal motion information.

FIG. 8 is a block diagram schematically illustrating an embodiment of an inter prediction apparatus capable of performing a process of deriving temporal motion information according to the embodiment of FIG. 6. In the inter prediction apparatus of FIG. 8, the temporal motion information determiner 810, the reconstructed neighboring block motion information determiner 820, the prediction direction information reset, the L0 motion information setter 830, and the L1 temporal motion information It may include a reset unit 840.

Referring to FIG. 8, the temporal motion information determination unit 810 determines whether L0 temporal motion information and L1 temporal motion information are the same in the input temporal motion information, that is, the L0 reference picture number and the L1 reference picture number are the same and the L0 motion vector. It may be determined whether and L1 motion vectors are the same.

When the L0 temporal motion information and the L1 temporal motion information are not the same, the inter prediction apparatus may use the input temporal motion information as the temporal motion information of the current block. When AMVP is applied, temporal motion information of the current block may be determined or registered as a predictive motion vector candidate for the current block. In addition, when merge is applied, temporal motion information of the current block may be determined or registered as a merge candidate for the current block. When the L0 temporal motion information and the L1 temporal motion information are the same, a determination process by the reconstructed neighboring block motion information determination unit 820 may be performed.

Meanwhile, as described above with reference to FIG. 6, the temporal motion information determining unit 810 predicts whether or not the L0 reference picture number and the L1 reference picture number are the same or the call block, rather than whether the L0 temporal motion information and the L1 temporal motion information are the same. You can also determine the direction. For example, when the L0 reference picture number and the L1 reference picture number are not the same, the inter prediction apparatus may use the input temporal motion information as the temporal motion information of the current block, and the L0 reference picture number and the L1 reference picture number are In the same case, the determination process by the restored neighboring block motion information determiner 820 may be performed. As another example, when the prediction direction of the call block is bidirectional prediction, the inter prediction apparatus may use the input temporal motion information as the temporal motion information of the current block as it is, and when the prediction direction of the call block is unidirectional prediction, the reconstructed neighboring block motion The determination process by the information determination unit 820 may be performed.

The reconstructed neighboring block motion information determiner 820 may determine whether there is motion information of the reconstructed neighboring block. When the motion information of the reconstructed neighboring block does not exist (for example, when there is no block having the motion information among the reconstructed neighboring blocks of the predetermined position and / or the position selected by the predetermined method), the prediction direction information The resetting and prediction direction information resetting by the L0 motion information setting unit 830 and the L0 motion information setting process may be performed. Further, when there is motion information of the restored neighboring block (for example, when there is a block having motion information among the restored neighboring blocks at the predetermined position and / or selected position in a predetermined method), L1 temporal movement The reset process by the information reset unit 840 may be performed.

When the motion information of the reconstructed neighboring block does not exist, the prediction direction information resetting and the L0 motion information setting unit 830 may set the prediction direction information of the current block to unidirectional prediction. In this case, the prediction direction information resetting and the L0 motion information setting unit 830 may set only the L0 temporal motion information among the input temporal motion information as the final temporal motion information of the current block.

When the motion information of the reconstructed neighboring block exists, the L1 temporal motion information resetting unit 840 may reset the L1 temporal motion information of the current block to the motion information of the reconstructed neighboring block. That is, the inter prediction apparatus may use the reconstructed motion information of the neighboring block as L1 temporal motion information of the current block. At this time, for example, when the L1 temporal motion information resetting unit 840 searches for motion information to be used as L1 temporal motion information of the current block in the restored neighboring block, the motion information having a zero vector (0, 0) is not selected. Only motion information without zero vector (0,0) may be selected. Meanwhile, the L1 temporal motion information resetting unit 840 may reset the L1 temporal motion information of the current block based on the motion information candidate list of the current block. Specific embodiments of each method described above have been described above with reference to FIGS. 6 and 7, and thus descriptions thereof will be omitted.

9 is a flowchart schematically showing another embodiment of a method for deriving temporal motion information of a current block according to the present invention.

Embodiments described below are described based on temporal motion information, but the present invention is not limited thereto. For example, the methods according to the embodiment of FIG. 9 are not only temporal motion information in the merge mode and / or AMVP mode, but also in the motion information and / or AMVP mode of the current block derived based on the merge candidate list in the merge mode. The same may be applied to the motion information of the current block derived based on the predicted motion vector candidate list in the same or similar manner.

As described above, the temporal motion information may be derived based on the motion information of the call block corresponding to the current block in the call picture that has already been restored. Here, the call picture may correspond to one picture from among reference pictures included in the reference picture list. The encoder and the decoder may determine a predetermined relative position with respect to a block existing at a position spatially identical to the current block in the call picture, and determine the predetermined relative position (eg, the same as the current block spatially). The call block may be derived based on a location inside and / or outside a block existing at a location. The temporal motion information derived based on the call block may include prediction direction information, an L0 reference picture number, an L1 reference picture number, an L0 motion vector, an L1 motion vector, and the like.

Referring to FIG. 9, the encoder and the decoder determine whether L0 temporal motion information and L1 temporal motion information are the same in temporal motion information derived based on a call block, that is, the L0 reference picture number and the L1 reference picture number are the same and the L0 motion is the same. It may be determined whether the vector and the L1 motion vector are the same (S910). Hereinafter, for the convenience of description, the temporal motion information input in step S910 before resetting temporal motion information is referred to as temporal motion information (L0 input temporal motion information and L1 input temporal motion information). do. In addition, the motion vector included in the input temporal motion information is an input motion vector (L0 input motion vector, L1 input motion vector), and the reference picture index included in the input temporal motion information is an input reference picture index (L0 input reference picture index, L1 input). The reference picture index) and the reference picture number included in the input temporal motion information are referred to as an input reference picture number (L0 input reference picture number and L1 input reference picture number).

When the L0 input temporal motion information and the L1 input temporal motion information are not the same, that is, the L0 input reference picture number and the L1 input reference picture number are not the same and / or the L0 input motion vector and the L1 input motion vector are not the same. The encoder and the decoder may use the input temporal motion information derived based on the call block as the temporal motion information of the current block. When AMVP is applied, temporal motion information of the current block may be determined or registered as a predictive motion vector candidate of the current block. In addition, when merge is applied, temporal motion information of the current block may be determined or registered as a merge candidate of the current block.

When the L0 input temporal motion information and the L1 input temporal motion information are the same, the encoder and the decoder may determine whether the motion information of the call block exists (S920). Here, the call block may be a newly derived call block, not a call block used for deriving input temporal motion information. For example, the encoder and the decoder may determine whether there is a block having motion information among call blocks of a predetermined position and / or a position selected by a predetermined method.

Hereinafter, for the convenience of description, the call block used for deriving the input temporal motion information is referred to as a first call block for convenience of description. As in step S940, the call block used for resetting the L1 input temporal motion information is referred to as a second call block. In addition, a call picture including a first call block is called a first call picture, and a call picture including a second call block is called a second call picture. Here, as an example, the first call picture and the second call picture may correspond to one picture among reference pictures included in the reference picture list, respectively.

If there is no motion information of the second call block (e.g., when there is no block having motion information among the second call blocks at a predetermined position and / or a position selected by a predetermined method), the encoder and decoding The device may reset the prediction direction information of the current block to unidirectional prediction (S930). In this case, the encoder and the decoder may use only L0 input temporal motion information as temporal motion information of the current block.

When there is motion information of the second call block (for example, when a block having motion information exists in a second call block at a predetermined position and / or a position selected by a predetermined method), the encoder and the decoder may The motion information of the second call block may be used as the final L1 temporal motion information of the current block (S940). That is, at this time, the encoder and the decoder may reset the L1 input temporal motion information of the current block to the motion information of the second call block. A specific embodiment of the second call picture and the second call block used for resetting the L1 input temporal motion information will be described later.

In the above-described embodiment, the method of deriving temporal motion information of the current block is described based on a flowchart as a series of steps, but one or more steps of the flowchart may be deleted. For example, the steps of S920 and S940 may be omitted in the above-described embodiment. In this case, when the L0 input temporal motion information and the L1 input temporal motion information are the same, the encoder and the decoder may set the prediction direction information of the current block to unidirectional prediction (S930). In this case, the encoder and the decoder may use only L0 input temporal motion information as final temporal motion information of the current block.

Meanwhile, in the above-described embodiment, it is determined whether the processes S920 to S940 are performed based on the sameness of the L0 input temporal motion information and the L1 input temporal motion information, but the encoder and the decoder may perform the processes S920 to S940 based on other conditions. May be determined.

In an embodiment, the encoder and the decoder may determine whether to perform the operations S920 to S940 based on the identity of the L0 input reference picture number and the L1 input reference picture number. For example, the encoder and the decoder may perform processes S920 to S940 when the L0 input reference picture number and the L1 input reference picture number are the same.

In another embodiment, the encoder and the decoder may determine whether to perform the processes S920 to S940 based on the prediction direction of the first call block. As described above, the prediction direction information may mean information indicating whether unidirectional prediction or bidirectional prediction is applied to a block on which prediction is performed. Therefore, the prediction direction may correspond to unidirectional prediction or bidirectional prediction. For example, the encoder and the decoder may perform processes S920 to S940 when the motion information (prediction direction) of the first call block is unidirectional prediction instead of bidirectional prediction. This is because when the prediction direction of the first call block is unidirectional prediction, the L0 input temporal motion information and the L1 input temporal motion information may be the same in the input temporal motion information derived from the first call block.

In another embodiment, the encoder and the decoder may determine whether to perform the processes S920 to S940 based on information on whether motion information exists in the first call block. For example, the encoder and the decoder may perform processes S920 to S940 when motion information does not exist in the first call block. In this case, in step S940, the L0 input temporal motion information may be reset instead of the L1 input temporal motion information. That is, the encoder and the decoder may set the L0 input temporal motion information as the motion information of the second collocated block, and may perform unidirectional prediction instead of bidirectional prediction with respect to the current block. In addition, when the motion information does not exist in the first call block, in step S940, the encoder and the decoder may reset both the L0 input temporal motion information and the L1 input temporal motion information. That is, the encoder and the decoder may reset both the L0 input temporal motion information and the L1 input temporal motion information to the motion information of the second call block, and may perform bidirectional prediction on the current block.

In another embodiment, the encoder and the decoder may determine whether to perform the processes S920 to S940 based on the size of the current block. As an example, the encoder and the decoder may determine whether the size of the current block is smaller than a predetermined size. Here, the current block may be a CU, a PU, and / or a TU, and the predetermined size may be, for example, one of 8x8, 16x16, or 32x32. In this case, the encoder and the decoder may perform processes S920 to S940 when the size of the current block is smaller than a predetermined size.

In another embodiment, the encoder and the decoder may perform processes S920 to S940 when the L0 motion vector and / or the L1 motion vector correspond to the zero vector (0,0) in the motion information of the first call block. In this case, in step S940, the encoder and the decoder may reset the motion vector (s) corresponding to the zero vector (0, 0). For example, the motion vector (s) corresponding to the zero vector (0,0) may be set as a motion vector of a second call block, and as another example, the motion vector corresponding to the zero vector (0,0) May be set as the motion vector of the reconstructed neighboring block. As another example, the motion vector (s) corresponding to the zero vector (0,0) may be a motion vector of a block located around the first call block. It may be set. In another embodiment, the encoder and the decoder may perform processes S920 to S940 when the L0 motion vector and / or the L1 motion vector do not correspond to the zero vector (0,0) in the motion information of the first call block. . In this case, in step S940, the encoder and the decoder may reset the motion vector (s) not corresponding to the zero vector (0,0), and the motion vector (s) not corresponding to the zero vector (0,0). ) May be reset to the motion vector of the second call block.

Conditions for determining whether to perform the processes S920 to S940 are not limited to the above-described embodiment, and various conditions may be applied according to conditions and / or needs.

In the above-described embodiments, since the L0 input temporal motion information and the L1 input temporal motion information are motion information derived in time, the L0 input temporal motion information is likely to correspond to motion information due to movement of an object. Therefore, when the encoder and the decoder search for motion information to be used as the final L1 temporal motion information of the current block in the second collocated block, the encoder and the decoder do not select the motion information having the zero vector (0,0) and zero vector (0,0). It is also possible to select motion information that does not have. This is because a block having motion information corresponding to a zero vector (0, 0) is likely to correspond to a background rather than an object.

Meanwhile, the reset last L1 temporal motion information may be the same as the L0 input temporal motion information of the current block. Accordingly, the encoder and the decoder may select motion information that is not the same as the L0 input temporal motion information when searching for motion information to be used as the final L1 temporal motion information of the current block in the second collocated block. For example, as in S940, when deriving the final L1 temporal motion information of the current block based on the second collocated block, the encoder and the decoder may select a block having motion information different from the L0 input temporal motion information of the current block. It may be determined as a block used for deriving final L1 temporal motion information. In this case, the encoder and the decoder may select only the motion information whose difference from the L0 input temporal motion information of the current block is less than or equal to a predetermined threshold as the motion information to be used as the final L1 temporal motion information. The predetermined threshold value may be determined based on mode information of the current block, motion information of the current block, mode information of a neighboring block, and / or motion information of a neighboring block, and may be determined in various ways.

In addition, in the above-described embodiments, the motion information of the second call block may include both L0 motion information and L1 motion information. In this case, the encoder and the decoder may determine one piece of motion information from the L0 motion information and the L1 motion information as the motion information to be used as the final L1 temporal motion information of the current block. For example, the encoder and the decoder may use the L0 motion information of the second collocated block as the final L1 temporal motion information for the current block. In this case, when the L0 motion information does not exist in the second call block, the encoder and the decoder may use the L1 motion information of the second call block as the final L1 temporal motion information for the current block. As another example, the encoder and the decoder may use the L1 motion information of the second collocated block as the final L1 temporal motion information for the current block. In this case, when the L1 motion information does not exist in the second call block, the encoder and the decoder may use the L0 motion information of the second call block as the final L1 temporal motion information for the current block.

Meanwhile, the encoder and the decoder may not use the motion information of the second call block to reset the L1 input temporal motion information (eg, the L1 input motion vector) of the current block in step S940. In this case, the encoder and the decoder may reset the L1 input temporal motion information (eg, the L1 input motion vector) of the current block based on the motion information (eg, the motion vector) of the first call block. Hereinafter, related embodiments will be described, which will be described with reference to a motion vector.

In one embodiment, the encoder and the decoder is a movement indicating a relative position moved based on a predetermined distance and / or direction at a position indicated by the motion information (motion vector) of the first call block within the first call picture. The information may be used as final L1 temporal motion information (L1 motion vector) of the current block. In one example, the encoder and the decoder are each 1/4 pixel size (for example, (-1,0), (1,0), () in a vertical and / or horizontal direction at a position indicated by the motion information of the first collocated block. 0, -1), (0,1), (-1, -1), (-1,1), (1, -1), (1,1), etc., where 1/4 pixel units are 1 The motion information indicating the moved position can be used as the final L1 temporal motion information of the current block. As another example, the encoder and the decoder may have a size of 1/2 pixel (for example, (-2,0), (2,0), () in a vertical and / or horizontal direction at a position indicated by the motion information of the first call block. 0, -2), (0,2), (-2, -2), (-2,2), (2, -2), (2,2), etc. where 1/4 pixel units are 1 The motion information indicating the moved position can be used as the final L1 temporal motion information of the current block. As another example, the encoder and the decoder may have integer pixel sizes (eg, (-4,0), (4,0), (0) in the vertical and / or horizontal directions at positions indicated by the motion information of the first call block. , -4), (0,4), (-4, -4), (-4,4), (4, -4), (4,4), etc. where 1/4 pixel units are The motion information indicating the moved position may be used as the final L1 temporal motion information of the current block. On the other hand, since the motion vector includes a vertical component and a horizontal component, the above-described methods (move by 1/4 pixel size, move by 1/2 pixel size, and move by integer pixel size) are the horizontal component and the vertical direction. Each of the components may be applied independently. In this case, the moving distance in the horizontal direction and the moving distance in the vertical direction may be different from each other.

In another embodiment, the encoder and the decoder may change the motion information (motion vector) value of the first call block to a value in other pixel units and then use the changed value as the final L1 temporal motion information (L1 motion vector) of the current block. have. For example, when the motion information value of the first call block is a value of 1/4 pixel unit, the encoder and decoder change the motion information value of the first call block to a value of 1/2 pixel unit based on a shift operation. The changed value may be used as final L1 temporal motion information of the current block. As another example, when the motion information value of the first call block is a value of 1/2 pixel unit, the encoder and decoder may change the motion information value of the first call block to a value of integer pixel unit based on a shift operation. The changed value may be used as final L1 temporal motion information of the current block.

The method of resetting L1 input temporal motion information (eg, L1 input motion vector) of the current block based on motion information (eg, motion vector) of the first call block is not limited to the above-described embodiment. It may be applied in various forms depending on the implementation and / or needs. In addition, the methods according to the above-described embodiments may be applied in the same or similar manner even when resetting the L1 input temporal motion information based on the motion information of the second call block as in step S940 of FIG. 9.

Meanwhile, in the above-described embodiment, the input temporal motion information input in step S910 may include not only an input motion vector but also an input reference picture index. Here, the L0 input motion vector and the L1 input motion vector may be motion vectors derived in time based on the first call block as described above, and the L0 input reference picture index and the L1 input reference picture index may be derived from the reconstructed neighboring block. It may be a spatially derived reference picture index. In this case, the L0 input reference picture index and the L1 input reference picture index may be set to the smallest non-negative value of the reference picture index of the reconstructed neighboring block. Meanwhile, as another example, the L0 input reference picture index and the L1 input reference picture index may be set to 0 regardless of the motion information of the reconstructed neighboring block.

When the L1 input motion vector is reset based on the second call block, a reset process may also be performed on the L1 input reference picture index. Hereinafter, embodiments of a resetting process for the L1 input reference picture index are described.

In an embodiment, the encoder and the decoder may reset the L1 input reference picture index based on the second call block. As described above, the encoder and the decoder may use the motion information of the second call block as the final L1 temporal motion information of the current block. In this case, the encoder and the decoder may derive the final L1 reference picture index by resetting the L1 input reference picture index to the reference picture index of the second call block. In another embodiment, the encoder and the decoder may derive the final L1 reference picture index by resetting the L1 input reference picture index value to a predetermined fixed reference picture index value.

In another embodiment, L0 input temporal motion information (eg, L0 input motion vector, L0 input reference picture index, etc.) and L1 input temporal motion information (eg, L1 input motion vector, L1 input reference picture index, etc.) ), The encoder and the decoder may reset both the L0 input reference picture index and the L1 input reference picture index to a value of 0 to use the final temporal motion information. This is because when the L0 input temporal motion information and the L1 input temporal motion information are the same, there is a high probability that both the L0 reference picture index and the L1 reference picture index are both zero.

In another embodiment, the encoder and the decoder may reset the L1 input reference picture index value to the same value as the L0 input reference picture index value. In contrast, the encoder and the decoder may reset the L1 input reference picture index value to a reference picture index value that is not the same as the L0 input reference picture index. Among the reference picture indexes of the reconstructed neighboring block, there may exist a reference picture index that is not the same as the L0 input reference picture index. In this case, for example, the encoder and the decoder may use the reference picture index most frequently used among the reference picture indices that are not the same as the L0 input reference picture index to reset the L1 input reference picture index. As another example, the encoder and the decoder may use the reference picture index having the smallest non-negative value among the reference picture indexes that are not the same as the L0 input reference picture index to reset the L1 input reference picture index.

Meanwhile, as described above, the encoder and the decoder may derive the final L1 temporal motion vector by resetting the L1 input motion vector value to the same value as the motion vector of the second call block. In this case, the motion vector of the second call block may be scaled and used according to an L1 input reference picture index and / or a reset L1 reference picture index. The L1 input reference picture index may be used as the final L1 reference picture index without resetting, or may be used as the final L1 reference picture index after resetting as in the above-described embodiment. In this case, the reference picture corresponding to the motion vector of the second collocated block and the reference picture indicated by the final L1 reference picture index may be different from each other. In this case, the encoder and the decoder may perform scaling on the motion vector of the second collocated block and use the scaled motion vector as the final L1 temporal motion vector of the current block.

The above-described embodiments may be combined and applied in various ways according to the resetting process of the motion vector and the resetting process of the reference picture index (eg, RefIdxLX, X = 0, 1). In the following embodiments, it is assumed that the L1 input motion vector is reset based on the second call block. That is, it is assumed that the encoder and the decoder reset the L1 input motion vector to one of the motion vectors of the second call block.

In one embodiment, the encoder and the decoder may use the first call picture used for deriving the L0 input temporal motion information as a second call picture, and the second call block may be derived from the second call picture. In this case, the encoder and the decoder may scale and use the motion vector of the second call block to reset the L1 input motion vector. In this case, the scaled motion vector may be used as final L1 temporal motion information. In this case, as an example, the L1 input reference picture index may be used as final L1 temporal motion information without resetting. That is, the encoder and the decoder may allocate the L1 input reference picture index as it is to the L1 temporal motion information of the current block. As another example, the L1 input reference picture index value may be reset to a predetermined fixed reference picture index value. That is, the encoder and the decoder may allocate a predetermined fixed reference picture index value to the L1 temporal motion information of the current block, and the predetermined fixed reference picture index may be used as the final L1 temporal motion information.

In another embodiment, the encoder and the decoder may use the first call picture used for deriving the L0 input temporal motion information as the second call picture as it is, and the second call block may use the second call picture. Can be derived from At this time, the encoder and the decoder derive a motion vector whose difference from the L0 input motion vector is not equal to the L0 input motion vector among the motion vectors of the second collocated block but less than a predetermined threshold value for resetting the L1 input motion vector. can do. The encoder and the decoder may perform scaling on the derived motion vector, and the scaled motion vector may be used as final L1 temporal motion information. In this case, as an example, the L1 input reference picture index may be used as final L1 temporal motion information without resetting. That is, the encoder and the decoder may allocate the L1 input reference picture index as it is to the L1 temporal motion information of the current block. As another example, the L1 input reference picture index value may be reset to a predetermined fixed reference picture index value. That is, the encoder and the decoder may allocate a predetermined fixed reference picture index value to the L1 temporal motion information of the current block, and the predetermined fixed reference picture index may be used as the final L1 temporal motion information.

In another embodiment, the encoder and the decoder may use a reference picture that is not the same as the first call picture used for deriving the L0 input temporal motion information as the second call picture. Here, the second call picture may be, for example, a reference picture most recently decoded among reference pictures in an L1 reference picture list that is not the same as the first call picture. As another example, the encoder and the decoder may select the reference picture with the highest frequency of use as the second call picture based on the reference picture number of the reconstructed neighboring block. The second call block may be derived from the second call picture. In this case, the encoder and the decoder may scale and use the motion vector of the second call block to reset the L1 input motion vector. In this case, the scaled motion vector may be used as final L1 temporal motion information. In this case, as an example, the L1 input reference picture index may be used as final L1 temporal motion information without resetting. That is, the encoder and the decoder may allocate the L1 input reference picture index as it is to the L1 temporal motion information of the current block. As another example, the L1 input reference picture index value may be reset to a predetermined fixed reference picture index value. That is, the encoder and the decoder may allocate a predetermined fixed reference picture index value to the L1 temporal motion information of the current block, and the predetermined fixed reference picture index may be used as the final L1 temporal motion information.

In another embodiment, the encoder and the decoder may use a reference picture that is not the same as the first call picture used to derive the L0 input temporal motion information as the second call picture, as in the above-described embodiment, and the second call block May be derived from the second call picture. Here, the second call picture may be, for example, a reference picture most recently decoded among reference pictures in an L1 reference picture list that is not the same as the first call picture. As another example, the encoder and the decoder may select the reference picture with the highest frequency of use as the second call picture based on the reference picture number of the reconstructed neighboring block. At this time, the encoder and the decoder derive a motion vector whose difference from the L0 input motion vector is not equal to the L0 input motion vector among the motion vectors of the second collocated block but less than a predetermined threshold value for resetting the L1 input motion vector. can do. The encoder and the decoder may perform scaling on the derived motion vector, and the scaled motion vector may be used as final L1 temporal motion information. In this case, as an example, the L1 input reference picture index may be used as final L1 temporal motion information without resetting. That is, the encoder and the decoder may allocate the L1 input reference picture index as it is to the L1 temporal motion information of the current block. As another example, the L1 input reference picture index value may be reset to a predetermined fixed reference picture index value. That is, the encoder and the decoder may allocate a predetermined fixed reference picture index value to the L1 temporal motion information of the current block, and the predetermined fixed reference picture index may be used as the final L1 temporal motion information.

Combinations of the embodiments of the process of resetting the motion vector and the process of resetting the reference picture index are not limited to the above-described embodiment, and various types of combinations as well as the above-described embodiments may be provided as required. have.

Meanwhile, the reset L1 temporal motion information may be the same as the L0 temporal motion information of the current block. Therefore, when the reset L1 temporal motion information is the same as the L0 temporal motion information of the current block, the encoder and the decoder may set the prediction direction information of the current block to unidirectional prediction. In this case, the encoder and the decoder may use only L0 temporal motion information as temporal motion information of the current block. Such a method may be applied to the present invention in combination with the above-described embodiments.

10 is a diagram schematically showing an embodiment of a second call block used for resetting L1 temporal motion information.

The encoder and the decoder may determine the second collocated block based on the colocated block existing at the same spatial position as the current block within the second collocated picture. In FIG. 10, block 1010 represents a current block, and block 1020 represents a co-located block in the second call picture. Here, the second call picture may be determined in various ways.

In an embodiment, the encoder and the decoder may determine one reference picture from among the reference pictures included in the L0 reference picture list as the second call picture. In one example, the encoder and the decoder may determine the first reference picture in the L0 reference picture list as the second call picture. As another example, the encoder and the decoder may determine the second reference picture in the L0 reference picture list as the second call picture. As another example, the encoder and the decoder may determine the third reference picture in the L0 reference picture list as the second call picture. As another example, the encoder and the decoder may determine the fourth reference picture in the L0 reference picture list as the second call picture.

In another embodiment, the encoder and the decoder may determine one reference picture from among the reference pictures included in the L1 reference picture list as the second call picture. In one example, the encoder and the decoder may determine the first reference picture in the L1 reference picture list as the second call picture. As another example, the encoder and the decoder may determine the second reference picture in the L1 reference picture list as the second call picture. As another example, the encoder and the decoder may determine the third reference picture in the L1 reference picture list as the second call picture. As another example, the encoder and the decoder may determine the fourth reference picture in the L1 reference picture list as the second call picture.

In another embodiment, the encoder and / or decoder may be configured to generate a reference picture that provides the highest coding efficiency among all the reference pictures (and / or some reference pictures determined according to a predetermined condition) in the L0 reference picture list and the L1 reference picture list. Can be used as a second call picture. Here, the encoding efficiency may be determined based on motion information of a block existing at a position corresponding to the second call block in each reference picture. In this case, the encoder may derive the second call picture based on the coding efficiency, and may transmit second call picture information indicating the second call picture to the decoder. The decoder may determine a second call picture based on the transmitted second call picture information.

In the above embodiments, the encoder and the decoder may determine only the reference picture that is not the same as the first call picture used for deriving the L0 input temporal motion information as the second call picture. In this case, only the reference picture that is not the same as the first call picture may be used for deriving the final L1 temporal motion information of the current block.

The second call picture determination method is not limited to the above-described embodiment, and the second call picture may be determined in other manners according to implementation and / or needs.

Meanwhile, in the embodiment of FIG. 10, the block located in the center of the same position block 1020 is block D, and the block located at the upper left corner of the sibling position block 1020 is block S, the same position block 1020. The block located in the lower left corner of the block Q, the block located in the upper right corner of the same position block 1020 inside the block R, the block located in the lower right corner inside the same position block 1020 is called block C. In addition, the block located at the top of the block adjacent to the left side of the same position block 1020 is block F, the block located at the bottom of the block adjacent to the left side of the same position block 1020 is block J, the same position block 1020 The leftmost block among the blocks adjacent to the top of the block G, the rightmost block among the blocks adjacent to the top of the same position block 1020 is the block M, the topmost block among the blocks adjacent to the right of the same position block 1020 The block located at is the block N, the lowest block among the blocks adjacent to the right side of the same location block 1020 is block B, the block located at the leftmost among the blocks adjacent to the bottom of the same location block 1020 is the block K, the same The rightmost block among blocks adjacent to the bottom of the location block 1020 is referred to as block A. FIG. In addition, the block located at the upper left corner outside of the same position block 1020 is block E, the block at the lower left corner outside the same position block 1020 is located at the block I, the upper right corner outside the same position block 1020. A block located is a block L, and a block located at a lower right corner outside the same location block 1020 is referred to as block H. In addition, a block located adjacent to the right side of the block B is a block P, and a block located adjacent to the lower end of the block A is called a block O.

As described above in the embodiment of FIG. 9, the encoder and the decoder may use the motion information of the second collocated block as the final L1 temporal motion information of the current block according to a predetermined condition. That is, the encoder and the decoder may reset the L1 input temporal motion information value to the motion information value of the second call block. In this case, the second call block and / or the motion may be derived from various methods used as the final L1 temporal motion information.

In one embodiment, the encoder and the decoder derives the motion information used as the final L1 temporal motion information from one block existing at a predetermined position with respect to the same position block among blocks located inside and / or outside the same position block. can do. At this time, one block existing in the predetermined position may correspond to the second call block. Here, the block of the predetermined position is a block A, block B, block C, block D, block E, block F, block G, block H, block I, block J, block K, block L, block M, block N , Block O, block P, block Q, block R or block S.

In another embodiment, the encoder and the decoder may scan, in a predetermined order, a plurality of blocks existing at a predetermined position among blocks located inside and / or outside the same position block. In this case, the encoder and the decoder may use the motion information of the first block in which the motion information exists in the scan order as the final L1 temporal motion information of the current block. Here, the first block in which the motion information exists may correspond to a second call block. The scan target block and the scan order may be determined in various forms. In one example, the encoder and the decoder may scan the blocks in the order of block H, block D, block A, block B, block C, block I, block J, block F, block G and block E.

In another embodiment, the encoder and the decoder may derive an intermediate value for motion information of a plurality of blocks existing at a predetermined position among blocks located inside and / or outside the same position block, and the derived intermediate value. Can be used as the final L1 temporal motion information of the current block. For example, the plurality of blocks may be block H, block D, block A, block B, block C, block I, block J, block F, block G, and block E.

The method of deriving L1 temporal motion information of the current block from the second collocated block is not limited to the above-described embodiment, and the L1 temporal motion information of the current block may be derived in various ways depending on implementation and / or need.

FIG. 11 is a block diagram schematically illustrating an embodiment of an inter prediction apparatus capable of performing a process of deriving temporal motion information according to the embodiment of FIG. 9. In the inter prediction apparatus of FIG. 11, the temporal motion information determiner 1110, the second call block motion information determiner 1120, the prediction direction information reset, the L0 motion information setter 1130, and the L1 temporal motion information are illustrated. It may include a reset unit 1140.

Referring to FIG. 11, the temporal motion information determiner 1110 determines whether the L0 input temporal motion information and the L1 input temporal motion information are the same in the input temporal motion information, that is, the L0 input reference picture number and the L1 input reference picture number are the same. It may be determined whether the L0 input motion vector and the L1 input motion vector are the same.

When the L0 input temporal motion information and the L1 input temporal motion information are not the same, the inter prediction apparatus may use the input temporal motion information as the temporal motion information of the current block. When AMVP is applied, temporal motion information of the current block may be determined or registered as a predictive motion vector candidate for the current block. In addition, when merge is applied, temporal motion information of the current block may be determined or registered as a merge candidate for the current block. When the L0 input temporal motion information and the L1 input temporal motion information are the same, a determination process by the second call block motion information determiner 1120 may be performed.

Meanwhile, as described above with reference to FIG. 9, the temporal motion information determiner 1110 determines whether the L0 input reference picture number and the L1 input reference picture number are the same or not, whether the L0 input temporal motion information and the L1 input temporal motion information are the same. The prediction direction of the first call block may be determined. For example, when the L0 input reference picture number and the L1 input reference picture number are not the same, the inter prediction apparatus may use the input temporal motion information as the temporal motion information of the current block as it is, and the L0 input reference picture number and the L1 input When the reference picture numbers are the same, a determination process by the second call block motion information determiner 1120 may be performed. As another example, when the prediction direction of the first call block is bidirectional prediction, the inter prediction apparatus may use the input temporal motion information as the temporal motion information of the current block as it is, and when the prediction direction of the first call block is unidirectional prediction, The determination process by the 2 call block motion information determination unit 1120 may be performed.

The second call block motion information determiner 1120 may determine whether motion information of the second call block exists. When the motion information of the second call block does not exist (for example, when there is no block having the motion information among the second call blocks of the predetermined position and / or the position selected by the predetermined method), the prediction direction information Resetting and predicting direction information by the L0 motion information setting unit 1130 and L0 motion information setting process may be performed. Further, when there is motion information of the second call block (eg, when there is a block having motion information among the second call blocks at a predetermined position and / or a position selected by a predetermined method), L1 temporal movement The reset process by the information reset unit 1140 may be performed.

When the motion information of the second call block does not exist, the prediction direction information resetting and the L0 motion information setting unit 1130 may set the prediction direction information of the current block to unidirectional prediction. In this case, the prediction direction information resetting and the L0 motion information setting unit 1130 may set only the L0 input temporal motion information among the input temporal motion information as the final temporal motion information of the current block.

When the motion information of the second call block exists, the L1 temporal motion information resetting unit 1140 may reset the L1 input temporal motion information of the current block to the motion information of the second call block. That is, the inter prediction apparatus may use the motion information of the second call block as the final L1 temporal motion information of the current block. At this time, if the motion information of the second call block includes a zero vector (0,0), the L1 temporal motion information resetting unit 1140 may determine the motion information of the block located near the second call block as the last of the current block. It can also be used as L1 temporal motion information. Specific embodiments of each method described above have been described above with reference to FIGS. 6 and 7, and thus descriptions thereof will be omitted.

12 is a diagram schematically showing an embodiment of a method for deriving motion information of a current block according to the present invention.

As described above, the encoder and the decoder may derive the motion information of the current block based on the motion information of the reconstructed neighboring block and / or the motion information of the call block. Here, the reconstructed neighboring block is a block in the current picture in which the reconstructed neighboring block is already encoded and / or decoded and reconstructed, and may include a block adjacent to the current block and / or a block located at an outer corner of the current block. In addition, the call block may mean a block corresponding to the current block in the call picture, and the call picture may correspond to one picture among reference pictures in the reference picture list, for example. In this case, the motion information derived from the reconstructed neighboring block may be referred to as spatial motion information, and the motion information derived based on the call block may be referred to as temporal motion information. In this case, the spatial motion information and the temporal motion information may each include prediction direction information, an L0 reference picture number, an L1 reference picture number, an L0 motion vector, an L1 motion vector, and the like.

Meanwhile, in the video decoding process, an undecoded picture may exist among previous pictures of the current picture (and / or a picture to be decoded) due to excessive traffic of the network. In this case, an incorrect call block may be used in the process of deriving temporal motion information for a block in the current picture, and since the correct temporal motion information may not be derived, the current picture may not be properly decoded. Accordingly, in order to solve the problem, in the encoder and the decoder deriving the motion information of the current block, one of the L0 motion information and the L1 motion information is spatially derived based on the reconstructed neighboring block, and the other is a call block. It can be derived based on time. That is, the encoder and the decoder may independently set the L0 motion information and the L1 motion information. In this case, even if there is a previous picture that has not been decoded, the encoder and the decoder may allow the current picture to be restored to some extent.

Referring to FIG. 12, an encoder and a decoder may set L0 motion information (1210). At this time, the encoder and the decoder use the spatially derived motion information (spatial motion information) based on the reconstructed neighboring block as L0 motion information, or the motion information (temporal motion information) derived temporally based on the call block. Can be used as L0 motion information. That is, the L0 motion information may be spatially derived based on the reconstructed neighboring block or temporally derived based on the call block.

Referring back to FIG. 12, the encoder and the decoder may set L1 motion information (1220). In this case, the encoder and the decoder use the spatially derived motion information (spatial motion information) based on the reconstructed neighboring block as L1 motion information, or the motion information (temporal motion information) derived temporally based on the call block. Can be used as L1 motion information. That is, the L1 motion information may be spatially derived based on the reconstructed neighboring block or temporally derived based on the call block.

In an embodiment, when the L0 motion information is motion information derived temporally based on the call block, the encoder and the decoder may use the spatial motion information derived based on the reconstructed neighboring block as the L1 motion information. In another embodiment, when the L0 motion information is motion information derived spatially based on the reconstructed neighboring block, the encoder and the decoder may use temporal motion information derived based on the call block as the L1 motion information.

Meanwhile, in the above-described embodiment, the encoder and the decoder may derive the L1 motion information based on the L0 motion information. For example, it is assumed that the L0 motion information is motion information derived based on the call block. In this case, as described above, the encoder and the decoder may use the spatial motion information spatially derived based on the reconstructed neighboring block as the L1 motion information. In this case, as an example, the encoder and the decoder may derive only motion information that is the same as or similar to the L0 motion information as spatial motion information to be used as the L1 motion information. As another example, the encoder and the decoder may derive only motion information that is not the same as the L0 motion information as spatial motion information to be used as the L1 motion information. In this case, the encoder and the decoder may derive only the motion information whose difference from the L0 motion information is less than or equal to a predetermined threshold as the spatial motion information to be used as the L1 motion information. The predetermined threshold value may be determined based on mode information of the current block, motion information of the current block, mode information of a neighboring block, and / or motion information of a neighboring block, and may be determined in various ways.

The method for setting the L0 motion information and the L1 motion information is not limited to the above-described embodiment and may vary according to implementation and / or needs.

Meanwhile, when the L0 motion information and / or the L1 motion information are spatially derived based on the motion information of the reconstructed neighboring block, the motion information of the reconstructed neighboring block is spatially derived spatial motion information and temporally derived temporal motion. It can also contain all the information. In this case, the encoder and the decoder may derive the L0 motion information of the current block and / or the L1 motion information of the current block by using only spatial motion information spatially derived from the restored motion information of the neighboring block.

Referring back to FIG. 12, the encoder and the decoder may derive the motion information of the current block by integrating the L0 motion information and the L1 motion information (1230).

Meanwhile, in the derived motion information of the current block, the L0 motion information and the L1 motion information may be identical to each other. Therefore, when the L0 motion information and the L1 motion information are the same, the encoder and the decoder may set the prediction direction information of the current block to unidirectional prediction. In this case, the encoder and the decoder may use only the L0 motion information as the motion information of the current block.

FIG. 13 is a block diagram schematically illustrating an embodiment of an inter prediction apparatus capable of performing a motion information derivation process according to the embodiment of FIG. 12. The inter prediction apparatus according to the embodiment of FIG. 13 may include an L0 motion information setting unit 1310, an L1 motion information setting unit 1320, and a motion information integrating unit 1330.

As described above in the embodiment of FIG. 12, the encoder and the decoder may independently set the L0 motion information and the L1 motion information. In this case, one of the L0 motion information and the L1 motion information may be spatially derived based on the reconstructed neighboring block, and the other may be derived temporally based on the call block.

Referring to FIG. 13, the L0 motion information setting unit 1310 may set the L0 motion information. At this time, the encoder and the decoder use the spatially derived motion information (spatial motion information) based on the reconstructed neighboring block as L0 motion information, or the motion information (temporal motion information) derived temporally based on the call block. Can be used as L0 motion information. That is, the L0 motion information may be spatially derived based on the reconstructed neighboring block or temporally derived based on the call block.

Referring back to FIG. 13, the L1 motion information setting unit 1320 may set the L1 motion information. In this case, the encoder and the decoder use the spatially derived motion information (spatial motion information) based on the reconstructed neighboring block as L1 motion information, or the motion information (temporal motion information) derived temporally based on the call block. Can be used as L1 motion information. That is, the L1 motion information may be spatially derived based on the reconstructed neighboring block or temporally derived based on the call block.

Since a specific embodiment of the method for setting the L0 motion information and the L1 motion information has been described above with reference to FIG. 12, it will be omitted here.

Referring back to FIG. 13, the motion information integrator 1330 integrates the L0 motion information set by the L0 motion information setter 1310 and the L1 motion information set by the L1 motion information setter 1320, thereby moving the current block. Information can be derived.

14 is a flowchart schematically illustrating still another embodiment of a method for deriving temporal motion information of a current block according to the present invention.

Embodiments described below are described based on temporal motion information, but the present invention is not limited thereto. For example, the methods according to the embodiment of FIG. 14 may not only provide temporal motion information in the merge mode and / or the AMVP mode, but also the motion information and / or the AMVP mode of the current block derived based on the merge candidate list in the merge mode. The same may be applied to the motion information of the current block derived based on the predicted motion vector candidate list in the same or similar manner.

As described above, the temporal motion information may be derived based on the motion information of the call block corresponding to the current block in the call picture that has already been restored. Here, the call picture may correspond to one picture from among reference pictures included in the reference picture list. The encoder and the decoder may determine a predetermined relative position with respect to a block existing at a position spatially identical to the current block in the call picture, and determine the predetermined relative position (eg, the same as the current block spatially). The call block may be derived based on a location inside and / or outside a block existing at a location. The temporal motion information derived based on the call block may include prediction direction information, an L0 reference picture number, an L1 reference picture number, an L0 motion vector, an L1 motion vector, and the like.

Referring to FIG. 14, the encoder and the decoder determine whether L0 temporal motion information and L1 temporal motion information are the same in temporal motion information derived based on a call block, that is, the L0 reference picture number and the L1 reference picture number are the same and the L0 motion is the same. It may be determined whether the vector and the L1 motion vector are the same (S1410).

14 to 15, which will be described later, for convenience of description, temporal motion information input in step S1410 before resetting temporal motion information is input temporal motion information (L0 input temporal motion information and L1 input temporal motion information). do. In this case, the input temporal motion information may correspond to temporal motion information derived based on a call block. In addition, the motion vector included in the input temporal motion information is an input motion vector (L0 input motion vector, L1 input motion vector), and the reference picture index included in the input temporal motion information is an input reference picture index (L0 input reference picture index, L1 input). The reference picture index) and the reference picture number included in the input temporal motion information are referred to as an input reference picture number (L0 input reference picture number and L1 input reference picture number). In addition, in the following embodiment, a reference picture indicated by the L0 input reference picture number is referred to as an L0 reference picture, and a reference picture indicated by the L1 input reference picture number is referred to as an L1 reference picture.

If the L0 temporal motion information and the L1 temporal motion information are not the same, i.e., the L0 reference picture number and the L1 reference picture number are not the same and / or the L0 motion vector and the L1 input motion vector are not the same, the encoder and the decoder The input temporal motion information derived based on the call block may be used as the final temporal motion information of the current block. When AMVP is applied, the final temporal motion information may be determined or registered as a predictive motion vector candidate of the current block. In addition, when merge is applied, the final temporal motion information may be determined or registered as a merge candidate of the current block.

When the L0 input temporal motion information and the L1 input temporal motion information are the same, the encoder and the decoder may search or derive the motion information to be used as the final L1 temporal motion information in the L1 reference picture (S1420). Here, since the L0 input temporal motion information and the L1 input temporal motion information are the same as each other, the L1 reference picture may correspond to the same picture as the L0 reference picture. Therefore, in the following embodiment, the L1 reference picture may mean the same picture as the L0 reference picture.

For example, the encoder and the decoder may search for and derive motion information from the L1 reference picture in the same manner. At this time, the encoder may not transmit the motion information derived from the L1 reference picture to the decoder. As another example, the encoder may derive motion information from the L1 reference picture by a predetermined method, and then include the derived motion information in a bitstream and transmit it to the decoder. At this time, the decoder may determine the motion information to be used as the final L1 temporal motion information based on the transmitted motion information. The motion information derived from the encoder may include a reference picture index and a motion vector, and the encoder may independently transmit the reference picture index and the motion vector to the decoder. In this case, the encoder may obtain a difference value between the actual motion vector of the current block and the motion vector derived from the L1 reference picture, and then transmit the difference value to the decoder.

Referring back to FIG. 14, the encoder and the decoder may use the motion information derived from the L1 reference picture as the final L1 temporal motion information of the current block (S1430). That is, at this time, the encoder and the decoder may reset the L1 input temporal motion information value to the value of the motion information derived from the L1 reference picture.

Hereinafter, embodiments of a method of deriving motion information to be used as final L1 temporal motion information in an L1 reference picture are described.

According to an embodiment, the encoder and the decoder may determine the final L1 temporal motion information based on the position indicated by the L0 input temporal motion information (motion vector) within the L1 reference picture and indicate the position existing within a predetermined range. Can be used as (L1 motion vector). Specifically, the predetermined range corresponds to a range including a position within + T and / or -T distance in the vertical and / or horizontal directions about a position indicated by the L0 input temporal motion information in the L1 reference picture. Can be. Here, for example, T may be a value representing a distance in units of 1/4 pixels, and as another example, T may be a value representing a distance in units of 1/2 pixels. As another example, T may be a value representing a distance in integer pixels. When integer pixel units are used, the computational complexity may be reduced since interpolation may not be performed during motion compensation.

As another example, the encoder may derive a region that best matches or similar to the input block (the original block) corresponding to the current block within the L1 reference picture. In this case, the encoder may derive motion information to be used as final L1 temporal motion information of the current block based on the derived region. For example, the encoder may derive a motion vector to be used as final L1 temporal motion information based on a position of a block corresponding to the derived region and a position of a current block, and may determine a final vector based on a block corresponding to the derived region. A reference picture index (and / or reference picture number) to be used as the L1 temporal motion information may be derived. The derived motion information may be included in the bitstream and transmitted from the encoder to the decoder. At this time, the decoder may reset the L1 input temporal motion information based on the transmitted motion information.

The reference picture index (and / or reference picture number) derived from the L1 reference picture may be different from the L1 input reference picture index (and / or L1 input reference picture number). In this case, the encoder and the decoder may use the reference picture index (and / or reference picture number) derived from the L1 reference picture as the final L1 temporal motion information of the current block.

The method of deriving the motion information to be used as the final L1 temporal motion information based on the L1 reference picture is not limited to the above-described embodiment, and the encoder and the decoder may derive the motion information in different ways depending on the implementation and / or the need. .

Meanwhile, in the above-described embodiment, whether to perform the processes S1420 to S1430 is determined based on the sameness of the L0 input temporal motion information and the L1 input temporal motion information, but whether the encoder and the decoder perform the processes S1420 to S1430 based on other conditions May be determined.

In an embodiment, the encoder and the decoder may determine whether to perform the processes S1420 to S1430 based on the prediction direction of the call block. As described above, the prediction direction information may mean information indicating whether unidirectional prediction or bidirectional prediction is applied to a block on which prediction is performed. Therefore, the prediction direction may correspond to unidirectional prediction or bidirectional prediction. For example, the encoder and the decoder may perform processes S1420 to S1430 when the motion information (prediction direction) of the call block is unidirectional prediction instead of bidirectional prediction. This is because when the prediction direction of the first call block is unidirectional prediction, the L0 input temporal motion information and the L1 input temporal motion information may be the same in the input temporal motion information derived from the first call block.

In another embodiment, the encoder and the decoder may determine whether to perform the operations S1420 to S1430 based on information on whether motion information exists in the call block. For example, the encoder and the decoder may perform processes S1420 to S1430 when there is no motion information in the call block. In this case, in step S1430 described above, the L0 input temporal motion information may be reset instead of the L1 input temporal motion information. That is, the encoder and the decoder may reset the L0 input temporal motion information to the motion information of the L1 reference picture, and may perform unidirectional prediction instead of bidirectional prediction on the current block. In addition, when there is no motion information in the call block, in step S1430, the encoder and the decoder may reset both the L0 input temporal motion information and the L1 input temporal motion information. That is, the encoder and the decoder may reset both the L0 input temporal motion information and the L1 input temporal motion information to the motion information of the L1 reference picture, and may perform bidirectional prediction on the current block.

In another embodiment, the encoder and the decoder may perform processes S1420 to S1430 when the L0 motion vector and / or the L1 motion vector correspond to the zero vector (0,0) in the motion information of the call block. In this case, in step S1430, the encoder and the decoder may reset the motion vector (s) corresponding to the zero vector (0, 0). For example, the motion vector (s) corresponding to the zero vector (0,0) may be set as a motion vector of an L1 reference picture, and as another example, the motion vector (s) corresponding to the zero vector (0,0) ) May be set as a motion vector of a reconstructed neighboring block, and as another example, the motion vector (s) corresponding to the zero vector (0,0) may be set as a motion vector of a block located around the call block. have. In another embodiment, the encoder and the decoder may perform processes S1420 to S1430 when the L0 motion vector and / or the L1 motion vector do not correspond to the zero vector (0,0) in the motion information of the collocated block. In this case, in step S1430, the encoder and the decoder may reset the motion vector (s) not corresponding to the zero vector (0,0), and the motion vector (s) not corresponding to the zero vector (0,0). ) May be reset to the motion vector of the L1 reference picture.

Conditions for determining whether to perform the processes of S1420 to S1430 are not limited to the above-described embodiment, and various conditions may be applied according to conditions and / or needs.

Meanwhile, the motion information derived from the L1 reference picture may be the same as the L0 input temporal motion information of the current block. Therefore, when the encoder and the decoder search for motion information to be used as the final L1 temporal motion information of the current block in the L1 reference picture, only the motion information that is not the same as the L0 input temporal motion information may be found. For example, as in S1430, when deriving the final L1 temporal motion information of the current block based on the L1 reference picture, the encoder and the decoder may determine only the final L1 temporal motion information that is different from the L0 input temporal motion information of the current block. Can be used as In this case, the encoder and the decoder may select only the motion information whose difference from the L0 input temporal motion information of the current block is less than or equal to a predetermined threshold as the motion information to be used as the final L1 temporal motion information. The predetermined threshold value may be determined based on mode information of the current block, motion information of the current block, mode information of a neighboring block, and / or motion information of a neighboring block, and may be determined in various ways.

In the above-described embodiment, the input temporal motion information input in step S1410 may include not only an input motion vector but also an input reference picture index. Here, the L0 input motion vector and the L1 input motion vector may be motion vectors derived temporally based on the call block as described above, and the L0 input reference picture index and the L1 input reference picture index may be spatially restored from the reconstructed neighboring block. It may be a derived reference picture index. In this case, the L0 input reference picture index and the L1 input reference picture index may be set to the smallest non-negative value of the reference picture index of the reconstructed neighboring block. Meanwhile, as another example, the L0 input reference picture index and the L1 input reference picture index may be set to 0 regardless of the motion information of the reconstructed neighboring block.

When the L1 input motion vector is reset based on the L1 reference picture, the resetting process may also be performed on the input reference picture index. As an example, the input reference picture index may be reset based on the reference picture index derived from the L1 reference picture as described above. As another example, L0 input temporal motion information (eg, L0 input motion vector, L0 input reference picture index, etc.) and L1 input temporal motion information (eg, L1 input motion vector, L1 input reference picture index, etc.) are the same. In this case, the encoder and the decoder may reset both the L0 input reference picture index and the L1 input reference picture index to a value of 0 and use the final temporal motion information. This is because when the L0 input temporal motion information and the L1 input temporal motion information are the same, there is a high probability that both the L0 reference picture index and the L1 reference picture index are both zero.

Meanwhile, as described above, the encoder and the decoder may derive the final L1 temporal motion vector by resetting the L1 input motion vector value to the same value as the motion vector of the L1 reference picture. In this case, the motion vector of the L1 reference picture may be scaled and used according to the L1 input reference picture index and / or the reset L1 reference picture index. The L1 input reference picture index may be used as the final L1 reference picture index without resetting, or may be used as the final L1 reference picture index after resetting as in the above-described embodiment. In this case, the reference picture corresponding to the motion vector of the L1 reference picture and the reference picture indicated by the final L1 reference picture index may be different from each other. In this case, the encoder and the decoder may perform scaling on the motion vector of the L1 reference picture and use the scaled motion vector as the final L1 temporal motion vector of the current block.

In addition, in the above-described embodiments, the reset L1 temporal motion information may be the same as the L0 temporal motion information of the current block. Therefore, when the reset L1 temporal motion information is the same as the L0 temporal motion information of the current block, the encoder and the decoder may set the prediction direction information of the current block to unidirectional prediction. In this case, the encoder and the decoder may use only L0 temporal motion information as temporal motion information of the current block. Such a method can be applied to the present invention in combination with the embodiments described above.

FIG. 15 is a block diagram schematically illustrating an embodiment of an inter prediction apparatus capable of performing a process of deriving temporal motion information according to the embodiment of FIG. 14. The inter prediction apparatus according to the embodiment of FIG. 15 may include a temporal motion information determiner 1510, a motion predictor 1520, and an L1 temporal motion information reset unit 1530.

As described above, the temporal motion information may be derived based on the motion information of the call block corresponding to the current block in the call picture that has already been restored. Here, the call picture may correspond to one picture from among reference pictures included in the reference picture list. The encoder and the decoder may determine a predetermined relative position with respect to a block existing at a position spatially identical to the current block in the call picture, and determine the predetermined relative position (eg, the same as the current block spatially). The call block may be derived based on a location inside and / or outside a block existing at a location. The temporal motion information derived based on the call block may include prediction direction information, an L0 reference picture number, an L1 reference picture number, an L0 motion vector, an L1 motion vector, and the like.

Referring to FIG. 15, referring to FIG. 11, the temporal motion information determiner 1510 determines whether L0 input temporal motion information and L1 input temporal motion information are the same in the input temporal motion information, that is, the L0 input reference picture number and L1. It may be determined whether the input reference picture number is the same and whether the L0 input motion vector and the L1 input motion vector are the same.

When the L0 input temporal motion information and the L1 input temporal motion information are not the same, the inter prediction apparatus may use the input temporal motion information as the temporal motion information of the current block. When AMVP is applied, temporal motion information of the current block may be determined or registered as a predictive motion vector candidate for the current block. In addition, when merge is applied, temporal motion information of the current block may be determined or registered as a merge candidate for the current block. When the L0 input temporal motion information and the L1 input temporal motion information are the same, a process by the motion predictor 1520 may be performed.

The temporal motion information determiner 1510 determines whether the L0 input reference picture number and the L1 input reference picture number are the same or the prediction direction of the call block, not whether the L0 input temporal motion information and the L1 input temporal motion information are the same. You may. For example, when the L0 input reference picture number and the L1 input reference picture number are not the same, the input temporal motion information may be used as the temporal motion information of the current block as it is, and the L0 input reference picture number and the L1 input reference picture number are In the same case, a process by the motion predictor 1520 may be performed. As another example, when the prediction direction of the call block is bidirectional prediction, the input temporal motion information may be used as the temporal motion information of the current block as it is, and the process by the motion prediction unit 1520 when the prediction direction of the call block is unidirectional prediction. May be performed.

Referring back to FIG. 15, when the L0 input temporal motion information and the L1 input temporal motion information are the same, the motion predictor 1520 may search or derive the motion information to be used as the final L1 temporal motion information in the L1 reference picture.

In an embodiment, the motion predictor 1520 may derive a region that best matches or similar to an input block (original block) corresponding to the current block within the L1 reference picture. In this case, the motion predictor 1520 may derive motion information to be used as final L1 temporal motion information of the current block based on the derived region. For example, the motion predictor 1520 may derive a motion vector to be used as final L1 temporal motion information based on the position of the block corresponding to the derived region and the position of the current block, and corresponds to the derived region. A reference picture index (and / or reference picture number) to be used as final L1 temporal motion information may be derived based on the block.

On the other hand, if the motion predictor 1520 corresponds to a component on the encoder side, the encoder may include the motion information derived from the L1 reference picture in the bitstream and transmit the same to the decoder. The motion information derived from the L1 reference picture may include a reference picture index and a motion vector, and the encoder may independently transmit the reference picture index and the motion vector to the decoder. In this case, the encoder may obtain a difference value between the actual motion vector of the current block and the motion vector derived from the L1 reference picture, and then transmit the difference value to the decoder.

In this case, the decoder may determine the motion information to be used as the final L1 temporal motion information based on the transmitted motion information. That is, when the motion predictor 1520 corresponds to a component on the decoder side, the motion predictor 1520 is finally based on the motion information (for example, motion information transmitted from the encoder) input from the outside. The motion information to be used as the L1 temporal motion information may be determined.

Referring back to FIG. 15, the L1 temporal motion information resetting unit 1530 may use motion information derived from the L1 reference picture as the final L1 temporal motion information of the current block. That is, at this time, the L1 temporal motion information reset unit 1530 may reset the L1 input temporal motion information value to the value of the motion information (motion information derived from the L1 reference picture) derived by the motion predictor 1520. .

6 to 15 may be applied individually, but may be combined and applied in various ways according to the encoding mode of each block. In the following embodiments, a block in which an encoding mode is a merge mode is called a merge block. In a block other than the merge block, for example, a block in which an encoding mode is an AMVP mode may be used. In addition, in the embodiments described below, the current block may correspond to one of a merge block or a block other than the merge block in some cases.

In one embodiment, the temporal motion information derivation method according to the embodiments of FIGS. 6 to 8 may be applied to the merge block, and the motion information derivation method according to FIGS. 12 and 13 may be applied to the block other than the merge block. In this case, in the merge block, when the L0 input temporal motion information and the L1 input temporal motion information are the same, the motion information of the reconstructed neighboring block may be used as the final L1 temporal motion information of the current block. In a block other than the merge block, the L0 motion information of the current block and the L1 motion information of the current block may be independently set. For example, one of the L0 motion information of the current block and the L1 motion information of the current block may be spatially derived based on the reconstructed neighboring block, and the other may be derived temporally based on the call block.

In another embodiment, the temporal motion information derivation method according to the embodiments of FIGS. 9 to 11 may be applied to the merge block, and the temporal motion information derivation method according to FIGS. 14 and 15 may be applied to the block other than the merge block. In this case, in the merge block, when the L0 input temporal motion information and the L1 input temporal motion information are the same, the motion information of the newly derived call block, rather than the call block used for deriving the input temporal motion information, is the last L1 temporal motion information of the current block. Can be used as In a block other than the merge block, when the L0 input temporal motion information and the L1 input temporal motion information are the same, the motion information of the L1 reference picture may be used as the final L1 temporal motion information of the current block.

In another embodiment, the temporal motion information derivation method according to the embodiments of FIGS. 6 to 8 may be applied to the merge block, and the temporal motion information derivation method according to FIGS. 14 and 15 may be applied to the block other than the merge block. In this case, in the merge block, when the L0 input temporal motion information and the L1 input temporal motion information are the same, the motion information of the reconstructed neighboring block may be used as the final L1 temporal motion information of the current block. In a block other than the merge block, when the L0 input temporal motion information and the L1 input temporal motion information are the same, the motion information of the L1 reference picture may be used as the final L1 temporal motion information of the current block.

The combination of the embodiments of FIGS. 6 to 15 is not limited to the above-described embodiment, and various types of combinations as well as the above-described embodiments may be provided according to implementation and / or need.

In the above embodiments, the methods are described based on a flowchart as a series of steps or blocks, but the present invention is not limited to the order of steps, and certain steps may occur in a different order or at the same time than other steps described above. Can be. It will also be understood by those skilled in the art that the steps depicted in the flowchart illustrations are not exclusive, that other steps may be included, or that one or more steps in the flowchart may be deleted without affecting the scope of the present invention. You will understand.

The above-described embodiments include examples of various aspects. While it is not possible to describe every possible combination for expressing various aspects, one of ordinary skill in the art will recognize that other combinations are possible. Accordingly, it is intended that the invention include all alternatives, modifications and variations that fall within the scope of the following claims.

Claims (9)

A motion predictor for deriving motion information of the current block as motion information including L0 motion information and L1 motion information;
A motion compensation unit configured to generate a prediction block corresponding to the current block by performing motion compensation on the current block based on at least one of the L0 motion information and the L1 motion information; And
A reconstruction block generator configured to generate a reconstruction block corresponding to the current block based on the prediction block;
The motion compensation unit,
And performing the motion compensation based on whether the L0 motion information and the L1 motion information are identical. The method of claim 1,
The L0 motion information includes an L0 motion vector and an L0 reference picture number, the L0 reference picture number indicates a picture order count (POC) assigned to the L0 reference picture,
The L1 motion information includes an L1 motion vector and an L1 reference picture number, and the L1 reference picture number indicates a picture order count (POC) assigned to the L1 reference picture. The method of claim 2,
When the L0 motion vector and the L1 motion vector are the same and the L0 reference picture number and the L1 reference picture number are the same,
The motion compensation unit,
And uni prediction is performed based on the L0 motion information among the L0 motion information and the L1 motion information. The method of claim 2,
When the L0 motion vector and the L1 motion vector are not equal to each other or the L0 reference picture number and the L1 reference picture number are not equal to each other,
The motion compensation unit,
And bi-prediction is performed based on the L0 motion information and the L1 motion information. A motion predictor for deriving motion information of the current block as motion information including L0 motion information and L1 motion information;
A motion compensation unit configured to generate a prediction block corresponding to the current block by performing motion compensation on the current block based on at least one of the L0 motion information and the L1 motion information; And
A reconstruction block generator configured to generate a reconstruction block corresponding to the current block based on the prediction block;
The motion compensation unit,
And the motion compensation is performed based on the size of the current block. 6. The method of claim 5,
If the size of the current block is smaller than a predetermined size,
The motion compensation unit,
And uni prediction is performed based on the L0 motion information among the L0 motion information and the L1 motion information. The method according to claim 6,
And the predetermined size is 8x8. A motion prediction unit for deriving motion information from a picture which has already been reconstructed;
A motion compensation unit generating a prediction block corresponding to the current block based on the derived motion information; And
A reconstruction block generator configured to generate a reconstruction block corresponding to the current block based on the prediction block;
The motion information includes a motion vector and a reference picture index.
The motion prediction unit,
And setting the reference picture index to 0 and deriving the motion vector based on a call block corresponding to the current block in the already reconstructed picture. The method of claim 8,
The encoding mode of the current block is a merge mode,
The motion compensation unit,
And generating the prediction block corresponding to the current block by selecting the temporal motion information as the motion information of the current block and performing motion compensation based on the selected motion information.

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