KR20190070313A - Method for inter prediction and apparatus thereof - Google Patents

Abstract

According to the present invention, an image decoding apparatus comprises: a motion prediction unit which derives motion information on a current block as motion information including L0 motion information and L1 motion information; a motion compensation unit which performs motion compensation for the current block on the basis of at least one of the L0 motion information and L1 motion information so as to generate a prediction block corresponding to the current block; and a restoration block generation unit which generates a restoration block corresponding to the current block based on the prediction block. According to the present invention, the image encoding efficiency can be increased.

Description

[0001] METHOD FOR INTER PREDICTION AND APPARATUS THEREOF [0002]

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

Recently, broadcasting service having high definition (HD) resolution has been expanded not only in domestic but also in the world, so that many users are accustomed to high-resolution and high-definition video, and thus many organizations are spurring development of next generation video equipment. In addition, with the increase of interest in UHD (Ultra High Definition) having resolution more than 4 times of HDTV in addition to HDTV, a compression technique for a higher resolution and a higher image quality is required.

An inter prediction technique for predicting pixel values included in the current picture from temporally preceding and / or following pictures for image compression, prediction of pixel values included in the current picture using pixel information in the current picture An intra prediction technique, an entropy coding technique in which a short code is assigned to a symbol having a high appearance frequency and a long code is assigned to a symbol having a low appearance frequency.

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

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

It is another object of the present invention to provide an inter prediction method and apparatus for improving image coding efficiency.

Another object of the present invention is to provide a motion information derivation method and apparatus that can improve image encoding efficiency.

Another aspect of the present invention is to provide a temporal motion information derivation method and apparatus that can improve image encoding efficiency.

One embodiment of the present invention is an image decoding apparatus. The apparatus includes a motion prediction unit for deriving motion information of a current block as motion information including L0 motion information and L1 motion information, motion estimation unit for estimating motion of the current block based on at least one of the L0 motion information and the L1 motion information, A motion compensation unit for generating a prediction block corresponding to the current block by performing compensation and a reconstruction block generation unit for generating a reconstruction block corresponding to the current block based on the prediction block, L0 motion information and the L1 motion information.

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

If 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 calculates, based on the L0 motion information among the L0 motion information and the L1 motion information, It is possible to perform uni prediction.

If the L0 motion vector and the L1 motion vector are not equal to each other, or if the L0 reference picture number and the L1 reference picture number are not equal to each other, the motion compensation unit calculates, based on the L0 motion information and the L1 motion information Bi prediction can be performed.

Another embodiment of the present invention is an image decoding apparatus. The apparatus includes a motion prediction unit for deriving motion information of a current block as motion information including L0 motion information and L1 motion information, motion estimation unit for estimating motion of the current block based on at least one of the L0 motion information and the L1 motion information, A motion compensation unit for generating a prediction block corresponding to the current block by performing compensation and a reconstruction block generation unit for generating a reconstruction block corresponding to the current block based on the prediction block, And performs the motion compensation based on the size of the current block.

If the size of the current block is smaller than a predetermined size, the motion compensation unit 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.

Still another embodiment of the present invention is an image decoding apparatus. The apparatus includes a motion prediction unit for deriving motion information from a reconstructed picture, a motion compensation unit for generating a prediction block corresponding to a current block based on the derived motion information, Wherein the motion information includes a motion vector and a reference picture index, the motion prediction unit sets the reference picture index to 0, And derives the motion vector based on a col block corresponding to the current block in the reconstructed picture.

Wherein the coding mode of the current block is a merge mode and the motion compensation unit selects the temporal motion information as motion information of the current block and performs motion compensation based on the selected motion information, Can be generated.

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

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

According to the inter prediction method of the present invention, image coding efficiency can be improved.

According to the motion information derivation method of the present invention, image encoding efficiency can be improved.

According to the temporal motion information deriving method according to the present invention, image encoding efficiency can 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 flow chart schematically showing an embodiment of the inter prediction method.
4 is a diagram schematically showing an embodiment of the 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 showing an embodiment of a temporal motion information deriving method of a current block according to the present invention.
7 is a diagram schematically showing an embodiment of a restored neighboring block used for resetting the L1 temporal motion information.
FIG. 8 is a block diagram schematically showing an embodiment of an inter prediction apparatus capable of performing a temporal motion information derivation process according to the embodiment of FIG.
9 is a flowchart schematically showing another embodiment of a temporal motion information deriving method 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 the L1 temporal motion information.
11 is a block diagram schematically showing an embodiment of an inter prediction apparatus capable of performing a temporal motion information derivation process according to the embodiment of FIG.
12 is a diagram schematically showing an embodiment of a method of deriving motion information of a current block according to the present invention.
13 is a block diagram schematically showing an embodiment of an inter prediction apparatus capable of performing a motion information derivation process according to the embodiment of FIG.
FIG. 14 is a flowchart schematically showing another embodiment of a temporal motion information deriving method of a current block according to the present invention.
15 is a block diagram schematically showing an embodiment of an inter prediction apparatus capable of performing a temporal motion information derivation process according to the embodiment of FIG.

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 is intra prediction, and inter prediction is 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 may code 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 can obtain a motion vector by searching an area of the reference picture stored in the reference picture buffer 190 that is best matched with the input block in 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 encoding unit 150 performs entropy encoding on the basis of values (e.g., quantized coefficients) calculated in the quantization unit 140 and / or encoding parameter values calculated in the encoding process, 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 encoding unit 150 may use an encoding method such as exponential golomb, context-adaptive variable length coding (CAVLC), and 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 predictive encoding, the currently encoded image needs to be decoded and stored for use 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 restoration block passes through the filter unit 180 and the filter unit 180 applies at least one of a deblocking filter, a sample adaptive offset (SAO), and an adaptive loop filter (ALF) 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 have occurred at the boundary between the 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 comparison between the reconstructed image and the original image, and may be performed only when high efficiency is applied. The reconstructed block having 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.

2, the image decoding apparatus 200 includes an entropy decoding unit 210, an inverse quantization unit 220, an inverse transform unit 230, an intra prediction unit 240, a motion compensation unit 250, (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 video 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 the image decoding can be enhanced through the entropy decoding method.

The quantized coefficients are inversely quantized in the inverse quantization unit 220 and inversely transformed in the inverse transformation unit 230. As a result that the quantized coefficients are inversely quantized / inverse transformed, a residual block can be generated.

In the intra mode, the intraprediction unit 240 may generate a prediction block by performing spatial prediction using the pixel value of the already decoded block around the current block. In the inter mode, the motion compensation unit 250 may generate a prediction block by performing motion compensation using a motion vector and a reference image stored in the reference picture buffer 270. [

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

Hereinafter, a block refers to a unit of image encoding and decoding. The coding or decoding unit in the image coding and decoding means a divided unit when the image is divided and encoded or decoded. Therefore, a coding unit (CU), a prediction unit (PU), a conversion unit (TU) : Transform Unit), a transform block, and the like. One block may be further subdivided into sub-blocks of smaller size. 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, a P picture, a B picture, and a forward B picture, which will be described later, may be replaced with P slice, B slice, and forward B slice, respectively, depending on the context.

3 is a flow chart schematically showing an embodiment of the inter prediction method.

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

In the inter mode, the encoder and the decoder may derive the motion information of the current block, and then perform inter prediction and / or motion compensation based on the derived motion information. At this time, the encoder and the decoder decode the motion information of the collocated block corresponding to the current block in the restored neighboring block and / or collocated picture already recovered The coding / 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. Also, the encoder and the decoder can determine a predetermined relative position based on a block existing at a position spatially coincident with the current block in the call picture, and determine the relative position between the determined relative position (present at a position spatially the same as the current block The location of the call block can be derived based on the internal and / or external location 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 method can be changed according to the prediction mode of the current block. The prediction mode applied for inter prediction may be an Advanced Motion Vector Predictor (AMVP), a merge, or the like.

For example, when an Advanced Motion Vector Predictor (AMVP) is applied, the encoder and the decoder can generate a predicted motion vector candidate list using a motion vector of a restored neighboring block and / or a motion vector of a 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 a predicted 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. At this time, the decoder can select the predicted motion vector of the current block from the predicted motion vector candidates included in the predicted motion vector candidate list using the predicted motion vector index.

The encoder can obtain a motion vector difference (MVD) between a motion vector of a current block and a predicted motion vector, and can encode the motion vector difference and transmit the motion vector to a decoder. At this time, the decoder can 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 a merge is applied, the encoder and the decoder can generate a merge candidate list using the motion information of the restored neighboring block and / or the motion information of the call block. That is, the encoder and the decoder can use the motion information of the restored neighboring block and / or call block as a merge candidate for the current block.

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

In the above-described AMVP and merge modes, motion information of a restored neighboring block and / or motion information of a call block may be used to derive motion information of the current block. Hereinafter, in the following embodiments, the motion information derived from the restored neighboring block is referred to as spatial motion information, and the motion information derived based on the call block is referred to as 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 again to FIG. 3, 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 be a motion compensated block generated as a result of performing motion compensation on a current block. In addition, a plurality of motion-compensated blocks may constitute one motion-compensated image. Accordingly, in the following embodiments, the prediction block may be referred to as a 'motion compensated block' and / or a 'motion compensated image' depending on the context, .

On the other hand, the P picture and the B picture may be included in the picture in which the inter prediction is performed. The P picture may mean a picture in which unidirectional prediction is performed using one reference picture, and the B picture may be a picture in which forward, backward, or bidirectional prediction using one or more, for example, two reference pictures can be performed can do. For example, in the B picture, inter prediction can be performed using one forward reference picture (past picture) and one reverse reference picture (future picture). 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 can be managed by a reference picture list. One reference picture is used in the P picture, and the reference picture can be allocated to the reference picture list 0 (L0 or List0). In the B picture, two reference pictures are used, and the two reference pictures can be assigned to the reference picture list 0 and the reference picture list 1 (L1 or List 1), 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 is assigned to the reference picture list 0 and the reverse reference picture can be assigned to the reference picture list 1. However, the method of allocating the reference picture is not limited to this. 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, the reference picture assigned to the reference picture list 0 is referred to as the L0 reference picture, and the reference picture assigned to the reference picture list 1 is referred to as the L1 reference picture.

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

As described above, in the P picture, unidirectional prediction using one L0 reference picture can be performed. In the B picture, one L0 reference picture and one L1 reference picture, i.e., two pictures in forward, Prediction can be performed. Prediction using one reference picture may be referred to as uni-prediction, and prediction using two reference pictures including the L0 reference picture and the L1 reference picture may be referred to as bi-prediction.

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

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

As described above, the encoder and the decoder can perform bidirectional prediction as well as unidirectional prediction upon inter prediction. When bidirectional prediction is applied, each block for which prediction is performed may have two reference pictures (L0 reference picture and L1 reference picture). Also, at this time, each block in which bidirectional prediction is performed may have two pieces of motion information. Here, the motion information may include a reference picture number, a motion vector, and the like.

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

Referring to FIG. 4, the encoder and the decoder may generate L0 motion compensated blocks by performing L0 motion compensation 410 for the current block using the L0 motion information and the L0 reference picture list. In addition, the encoder and the decoder can generate L1 motion compensated blocks by performing L1 motion compensation 420 using L1 motion information and L1 reference picture list. In this case, the L0 motion compensation 410 and the L1 motion compensation 420 processes may be performed independently of each other.

The encoder and 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. In one example, the weighted average 430 may be performed on a pixel-by-pixel basis within 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, the motion compensation applied in bidirectional prediction is referred to as bidirectional motion compensation. Corresponding to this, the motion compensation applied in unidirectional prediction can be called unidirectional motion compensation.

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

The image encoded in FIG. 5 corresponds to BasketballDrill. Here, BasketballDrill represents the name of a test sequence used for image coding / decoding experiments. The size of the encoded image is 832x480 and the picture order count (POC) is 2. In addition, the quantization parameter (QP) value applied to the image of FIG.

The encoder and decoder may use a forward B picture to enhance inter prediction efficiency in a low latency 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 for which prediction is performed may have two pieces of motion information (L0 motion information, L1 motion information). In the forward B picture, the L0 reference picture list and the L1 reference picture list can be set to be the same in general. Hereinafter, when the forward B picture is used, it is assumed that the L0 reference picture list and the L1 reference picture list are the same.

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, but it may be determined whether the current picture is a forward B picture based on the information transmitted from the encoder It is possible. For example, the encoder can encode a flag indicating whether the L0 reference picture list and the L1 reference picture list are the same, and transmit them to the decoder. At this time, the decoder may receive and decode the flag, and then, based on the decoded flag, determine whether the current picture is a forward B picture. As another example, the encoder may transmit the NAL unit type value or the slice type value corresponding to the forward B picture to the decoder, and the decoder may receive the value and 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. Thus, each block in the encoded image can have a maximum of two pieces of motion information. Here, the motion information may include a reference picture number, a motion vector, and the like. Referring to FIG. 5, blocks having the same L0 motion information (for example, reference picture number and motion vector) and L1 motion information (for example, reference picture number and motion vector) among blocks having two pieces of motion information There can be many.

A block in which the L0 motion information (e.g., reference picture number, motion vector) and the L1 motion information (e.g., reference picture number, motion vector) are the same in the forward B picture may occur due to the temporal motion information derivation method have. As described above, the temporal motion information can be derived from the motion information of the call block corresponding to the current block in the reconstructed call picture. For example, when the L0 temporal motion information of the current block is derived, the encoder and the decoder can use the L0 motion information of the call block corresponding to the current block in the call picture. However, if there is no L0 motion information in the call block, the encoder and the decoder can use L1 motion information of the call block as L0 temporal motion information of the current block. On the contrary, when deriving the L1 temporal motion information of the current block, the encoder and the decoder can use the L1 motion information of the call block corresponding to the current block in the call picture. However, if there is no L1 motion information in the call block, the encoder and the decoder can 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, the L0 motion information and the L1 motion information of the current block become equal to each other. Therefore, in the present specification, when L0 motion information (for example, reference picture number and motion vector) and L1 motion information (for example, reference picture number and motion vector) are the same, and / or L0 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 in the already reconstructed call picture is L0 Motion information, and L1 motion information.

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

When the motion compensation is performed on a block in which L0 motion information and L1 motion information are the same, the same process may be repeated twice in one block. The inter prediction method and / or the motion compensation method, which can solve the above-described problems and reduce the calculation complexity and improve the coding efficiency, can be provided since it is very inefficient from the viewpoint of coding. For example, when L0 motion information (e.g., reference picture number and motion vector) and L1 motion information (e.g., 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. In another example, if L0 motion information (e.g., reference picture number and motion vector) and L1 motion information (e.g., reference picture number and motion vector) are the same, then the encoder and decoder may use L0 motion information and / The encoding efficiency may be increased by resetting the information.

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

Although the embodiments described below are described based on temporal motion information, the present invention is not limited thereto. For example, the methods according to the embodiment of FIG. 6 may include not only temporal motion information in the merge mode and / or the AMVP mode, but also motion information of the current block derived based on the merge candidate list in the merge mode and / And 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 can be derived based on the motion information of the call block corresponding to the current block in the reconstructed call picture. Here, the call picture may correspond to one picture among the reference pictures included in the reference picture list, for example. The encoder and the decoder can determine a predetermined relative position based on a block existing at a position spatially coincident with the current block in the call picture, and determine the relative position based on the determined relative position (for example, The location of the call block may be derived based on the internal and / or external location of the block in the location). The temporal motion information derived based on the call block may include the prediction direction information, the L0 reference picture number, the L1 reference picture number, the L0 motion vector, and the L1 motion vector.

Referring to FIG. 6, the encoder and decoder decides whether or not L0 temporal motion information and L1 temporal motion information are the same in the temporal motion information derived based on the call block, that is, whether the L0 reference picture number and the L1 reference picture number are the same, It is possible to determine 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, 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 motion vector are not the same, The temporal motion information derived based on the block can be used as temporal motion information for the current block as it is. If AMVP is applied, the temporal motion information of the current block may be determined or registered as a predicted motion vector candidate for the current block. Also, if a merge is applied, the 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 can determine whether motion information of the restored neighboring block exists (S620). For example, at this time, the encoder and the decoder may determine whether there is a block having motion information among the reconstructed neighboring blocks at a predetermined position and / or a predetermined position in a predetermined manner. 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 motion information of the restored neighboring block does not exist (for example, a block having motion information does not exist in a restored neighboring block at a predetermined position and / or a position selected by a predetermined method) The prediction direction information of the current block can be set again as unidirectional prediction (S630). In this case, the encoder and the decoder can use only L0 temporal motion information as temporal motion information of the current block.

When there is motion information of the restored neighboring block (for example, when there is a block having motion information among restored neighboring blocks of a predetermined position and / or a position selected by a predetermined method), the encoder and the decoder The motion information of the restored neighboring block may be used as the L1 temporal motion information of the current block (S640). That is, at this time, the encoder and the decoder can reset the L1 temporal motion information of the current block to the motion information of the restored neighboring block. Specific embodiments of the restored neighboring blocks used for setting the L1 temporal motion information will be described later.

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

On the other hand, in the above-described embodiment, whether or not to perform the processes of S620 to S640 is determined based on the identities of the L0 temporal motion information and the L1 temporal motion information, but the encoder and the decoder determine whether to perform the processes of S620 through S640 It is possible.

In one embodiment, the encoder and the decoder may determine whether to perform the steps S620 to S640 based on the identities of the L0 reference picture number and the L1 reference picture number in temporal motion information derived based on the call block. For example, the encoder and the decoder may perform steps 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 steps S620 to S640 based on the prediction direction of the call block. As described above, the prediction direction information may refer to information indicating whether unidirectional prediction is applied to the block on which prediction is performed, or whether bidirectional prediction is applied. Accordingly, the prediction direction may correspond to unidirectional prediction or bidirectional prediction. For example, the encoder and the decoder may perform steps S620 to S640 when the motion information (prediction direction) of the call block is unidirectional prediction rather than bidirectional prediction. This is because, if the prediction direction of the call block is unidirectional prediction, the L0 temporal motion information and the L1 temporal motion information may be the same in the temporal motion information derived based on the call block.

According to another embodiment, the encoder and the decoder may determine whether or not to perform the processes of S620 to S640 based on information on whether motion information is present in the call block. For example, if there is no motion information in the call block, the encoder and the decoder may perform steps S620 to S640. In this case, in step S640, the L0 temporal motion information other than the L1 temporal motion information may be reset. That is, the encoder and decoder can set the L0 temporal motion information as the motion information of the reconstructed neighboring block, and perform unidirectional prediction for the current block instead of bi-directional prediction. If there is no motion information in the call block, the encoder and the decoder may reset both the L0 temporal motion information and the L1 temporal motion information in step S640. That is, the encoder and the decoder can set the L0 temporal motion information and the L1 temporal motion information as motion information of the reconstructed neighboring block, and perform bi-directional prediction on the current block.

In another embodiment, the encoder and the decoder may determine whether to perform S620 through S640 based on the size of the current block. For 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, 8x8, 16x16, or 32x32. In this case, the encoder and the decoder may perform steps S620 to S640 when the size of the current block is smaller than a predetermined size.

In another embodiment, the encoder and the decoder may perform steps S620 to S640 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 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 the motion vector of the restored neighboring block, and as another example, the motion vector ) May be set as a motion vector of a block located around the call block. In another embodiment, the encoder and the decoder may perform steps 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) ) Can be reset to the motion vector of the restored neighboring block.

The conditions for determining whether to perform the processes of S620 to S640 are not limited to the above-described embodiments, and various conditions may be applied depending on the conditions and / or the necessity.

If AMVP is applied, the encoder and / or the decoder can use, as the predicted motion vector of the current block, the candidate having the smallest difference from the motion vector of the current block among the predicted motion vector candidates in the predicted motion vector candidate list, The encoder and / or the decoder can use the merge candidate that can provide the optimal encoding efficiency among the merge candidates in the merge candidate list as the motion information for the current block. The predicted motion vector candidate list and the merge candidate list may each include temporal motion information and / or spatial motion information, so that motion information of the current block (e.g., reference picture number, motion information, etc.) Can be derived based on motion information of the block. Therefore, in the above-described L1 temporal motion information resetting step S640, the encoder and the decoder can 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 restored neighboring block exists may be omitted. Hereinafter, in the following embodiments, the motion information candidate list can 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 can 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 can use one of the motion information candidates included in the motion information candidate list of the current block as the L1 temporal motion information. The motion information used as the L1 temporal motion information in the motion information candidate list of the current block can be determined by various methods.

In one embodiment, the encoder and the decoder may sequentially search motion information candidates in the motion information candidate list from the first motion information candidate to the last motion information candidate. At this time, the encoder and the decoder can 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. At this time, 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 may use the L0 motion information of the first motion information candidate having the same reference picture number as the L1 reference picture number May be used. On the other hand, 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, to the motion information candidate list, motion information having the same reference picture number as the L1 reference picture number among the motion information of the restored neighboring blocks. At this time, the encoder and the decoder can reset the L1 temporal motion information of the current block based on the motion information candidate list to which the motion information of the restored neighboring block is added.

In another embodiment, the encoder and the decoder may use the motion vector of the first motion information candidate having a motion vector available 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 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, 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 the L1 motion information of the first motion information candidate.

The method of 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 depending on the condition and / or the necessity.

In the above-described embodiments, there may be no motion information available in the motion information candidate list of the current block. In this case, for example, the encoder and the decoder may use the motion information of the restored neighboring block as the L1 temporal motion information of the current block, as in step S640. In another example, the encoder and the decoder may add the motion information of the restored neighboring block to the motion information candidate list or add the zero vector (0, 0) to the motion information candidate list. At this time, the encoder and decoder can reset the L1 temporal motion information of the current block based on the motion information candidate list to which the motion information of the restored 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, the L0 temporal motion information and the L1 temporal motion information are temporally derived motion information, and therefore, there is a high possibility that the L0 temporal motion information and the L1 temporal motion information correspond to motion information due to the movement of the object. Therefore, when searching the motion information to be used as the L1 temporal motion information of the current block in the restored neighboring block and / or motion information candidate list, the encoder and the decoder do not select the motion information having the zero vector (0,0) Motion information having no vector (0, 0) may be selected. 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, when searching for motion information to be used as L1 temporal motion information of the current block in the restored neighboring block and / or motion information candidate list, the encoder and the decoder can select motion information that is not the same as the L0 temporal motion information. For example, in the case of deriving the L1 temporal motion information of the current block based on the reconstructed neighboring block as in S640, the encoder and the decoder may calculate a block having L0 temporal motion information and other motion information of the current block, L1 can be determined as a block used for deriving temporal motion information. At this time, 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 value, as motion information to be used as the L1 temporal motion information of the current block. Here, the predetermined threshold may be determined based on mode information of a current block, motion information of a current block, mode information of a neighboring block, motion information of neighboring blocks, or the like, and may be determined in various ways.

Also, in the above-described embodiments, the motion information of the restored neighboring block and the motion information selected from the motion information candidate list may include both L0 motion information and L1 motion information, respectively. In this case, the encoder and the decoder may determine one of the L0 motion information and the L1 motion information as motion information to be used as L1 temporal motion information of the current block. For example, the encoder and the decoder may use the L0 motion information in the motion information of the restored neighboring block and / or the motion information selected from the motion information candidate list as the L1 temporal motion information of the current block. At this time, if there is no L0 motion information in the motion information of the restored neighboring block and / or the motion information selected from the motion information candidate list, 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 in the motion information of the restored neighboring block and / or the motion information selected from the motion information candidate list as the L1 temporal motion information of the current block. In this case, when the L1 motion information does not exist in the motion information of the restored neighboring block and / or the motion information selected from the motion information candidate list, the encoder and the decoder may use the L0 motion information as the L1 temporal motion information of the current block .

On the other hand, in step S640, the encoder and the decoder use the motion information and / or the motion information candidate list of the restored neighboring blocks to reset L1 temporal motion information (for example, L1 motion vector) of the current block It is possible. At this time, the encoder and the decoder can reset L1 temporal motion information (for example, L1 motion vector) of the current block based on L0 temporal motion information (e.g., L0 motion vector) of the current block. Hereinafter, embodiments related thereto will be described, which will be described based on a motion vector.

In one embodiment, the encoder and the decoder output motion information indicating a relative position moved based on a predetermined distance and / or direction at a position indicated by the L0 temporal motion information (L0 motion vector) of the current block to L1 Can be used as temporal motion information (L1 motion vector). For example, the encoder and the decoder may divide the horizontal and vertical 1/4 pixel sizes (e.g., (-1,0), (1,0), and 1, -1), (1, 1), etc. Here, the 1/4 pixel unit is 1 The motion information indicating the moved position can be used as the L1 temporal motion information of the current block. As another example, the encoder and the decoder may divide the picture in the vertical and / or horizontal direction by a half pixel size (e.g., (-2,0), (2,0), ( (2, -2), (2, 2), etc. Here, the 1/4 pixel unit is 1 The motion information indicating the moved position can be used as the L1 temporal motion information of the current block. As another example, the encoder and the decoder may use an integer pixel size (for example, (-4,0), (4,0), (0), and (0,0) in the vertical and / or horizontal direction at the position indicated by the L0 temporal motion information of the current block. , -4), (0,4), (-4,4), (-4,4), (4,4), (4,4) The motion information indicating the moved position may be used as the L1 temporal motion information of the current block. On the other hand, since the motion vector includes the vertical direction component and the horizontal direction component, the above-described methods (movement by 1/4 pixel size, movement by 1/2 pixel size, movement by integer pixel size) May be independently applied to each component. At this time, 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 decoder change the value of L0 temporal motion information (L0 motion vector) of the current block to a value of another pixel unit, and use the changed value as L1 temporal motion information (L1 motion vector) of the current block . For example, when the value of the L0 temporal motion information of the current block is a value of a quarter pixel unit, the encoder and the decoder may change the value of the L0 temporal motion information to a value of a half pixel unit based on a shift operation or the like And may use the changed value as the 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 a half-pixel unit, the encoder and the decoder can change the value of the L0 temporal motion information to a value of an integer pixel unit based on a shift operation or the like, And may use the changed value as the L1 temporal motion information of the current block.

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

Meanwhile, in the above-described embodiment, the temporal motion information input to the step S610 before the temporal motion information resetting 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 temporally derived motion vectors based on the call block as described above, and the L0 reference picture index and the L1 reference picture index may be referred to as a reference picture spatially derived from the restored neighboring block Lt; / RTI > In this case, the L0 reference picture index and the L1 reference picture index may be set to the smallest non-negative value in the reference picture index of the restored neighboring block. On the other hand, 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 restored neighboring block.

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

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

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

In one embodiment, the encoder and decoder may reset the L1 input reference picture index based on the reconstructed neighboring block. As described above, the encoder and the decoder can use the motion information of the restored neighboring blocks as the L1 temporal motion information of the current block. At this time, the encoder and the decoder can derive the final L1 reference picture index by resetting the L1 input reference picture index to the reference picture index of the restored neighboring block. In another embodiment, the encoder and 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 (e.g., L0 input motion vector, L0 input reference picture index, etc.) and L1 input temporal motion information (e.g., L1 input motion vector, L1 input reference picture index, ) Are the same, 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 it as 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 of the L0 reference picture index and the L1 reference picture index are zero.

In another embodiment, the encoder and decoder may reset the L1 input reference picture index to the same value as the L0 input reference picture index. On the other hand, the encoder and decoder may reset the L1 input reference picture index value to a reference picture index value not equal to 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 in the reference picture index of the restored neighboring block. In this case, for example, the encoder and the decoder may use the most frequently used reference picture index among the reference picture indexes which are not the same as the L0 input reference picture index, in order to reset the L1 input reference picture index. As another example, the encoder and decoder may use a reference picture index having the smallest non-negative reference picture index, which is not the same as the L0 input reference picture index, for resetting the L1 input reference picture index.

Meanwhile, as described above, the encoder and the decoder can 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 according to the L1 input reference picture index and / or the reset L1 reference picture index. In the L1 input temporal motion information, the L1 input reference picture index may be used as the final L1 temporal motion information without resetting, or may be used as the final L1 temporal motion information through a reset process as in the above embodiment. At this time, the reference picture corresponding to the motion vector of the restored neighboring 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 restored neighboring block and use the scaled motion vector as the last L1 temporal motion information of the current block.

The above-described embodiments may be applied in various ways in accordance with the process of resetting the motion vector and the process of resetting the reference picture index (e.g., RefIdxLX, X = 0, 1). In the following embodiments, it is assumed that the L1 input motion vector is reset based on the restored neighboring blocks. 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 restored neighboring block.

In one embodiment, the encoder and the decoder may use only motion vectors that are not zero vectors (0,0) among the motion vectors of the reconstructed neighboring blocks, for resetting the L1 input motion vectors. In this case, for example, the L1 input reference picture index can be used as final L1 temporal motion information without resetting. As another example, the L1 input reference picture index value can be reset to the reference picture index value of the restored neighboring block, and the reset reference picture index can be used as the last 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 examples of each of these have been described above, and therefore, will not be described here.

In another embodiment, the encoder and the decoder may use a motion vector of a reconstructed neighboring block for scaling the L1 input motion vector. In this case, the scaled motion vector may be used as the last L1 temporal motion information. In this case, for example, the L1 input reference picture index can be used as final L1 temporal motion information without resetting. As another example, the L1 input reference picture index value can be reset to the reference picture index value of the restored neighboring block, and the reset reference picture index can be used as the last 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 examples of each of these have been described above, and therefore, will not be described here.

In another embodiment, the encoder and the decoder may use only motion vectors whose difference from the L0 temporal motion information (L0 motion vector) of the current block in the reconstructed neighboring block 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 motion vectors of the restored neighboring block. In this case, for example, the L1 input reference picture index can be used as final L1 temporal motion information without resetting. As another example, the L1 input reference picture index value can be reset to the reference picture index value of the restored neighboring block, and the reset reference picture index can be used as the last 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 examples of each of these have been described above, and therefore, will not be described here.

The combination of embodiments of the process of resetting the motion vector and the process of resetting the reference picture index is not limited to the above-described embodiment, and various combinations of the embodiments described above and / 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. Accordingly, if the reset L1 temporal motion information is the same as the L0 temporal motion information of the current block, the encoder and decoder can set the prediction direction information of the current block back to unidirectional prediction. At this time, the encoder and the decoder can use only L0 temporal motion information as temporal motion information of the current block. This method can be applied to the present invention as a combination with the above-described embodiments.

7 is a diagram schematically showing an embodiment of a restored neighboring block used for resetting the L1 temporal motion information. Block 710 in FIG. 7 represents the current block X. FIG.

As described above, the reconstructed neighboring block may include a block adjacent to the current block 710 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. 7, a block located at the lower left corner outside the current block 710 is referred to as a lower left corner block A, and a block located at the upper left corner outside the current block 710 is referred to as a left upper corner block E ), And a block located at the upper right corner outside the current block 710 is referred to as a right upper corner block (C). A block located at the uppermost of the blocks adjacent to the left of the current block 710 is referred to as a left top block F and a block located at the bottom of the blocks adjacent to the left of the current block 710 is referred to as a leftmost bottom block A, A block located at the leftmost of the blocks adjacent to the upper end of the current block 710 is referred to as an uppermost left block G and a block located at the rightmost end of the block adjacent to the upper end of the current block 710 is referred to as an uppermost right block B,

As described above with reference to FIG. 6, the encoder and the decoder can use the motion information of the reconstructed neighboring blocks according to a predetermined condition as the L1 temporal motion information of the current block. That is, the encoder and the decoder can reset the L1 temporal motion information value of the current block to the motion information value of the reconstructed neighboring block. At this time, the motion information used as the L1 temporal motion information of the current block can be derived by various methods.

In one embodiment, the encoder and the decoder may derive motion information used as L1 temporal motion information from one block existing at a predetermined position among the restored neighboring blocks. At this time, the block at the predetermined position is divided into a leftmost lowermost block A, an uppermost right block B, a right upper corner block C, a left lower corner block D, a left upper corner block E, The uppermost block F and the uppermost left block G, respectively.

In another embodiment, the encoder and the decoder may scan a plurality of blocks existing at a predetermined position among the restored neighboring blocks in a predetermined order. In this case, the encoder and the decoder can 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 can be set 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 left most block B, and the top right most block B, respectively. As another example, the encoder and the decoder may block the neighboring blocks in the order of the left uppermost block F, the uppermost left block G, 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 scan the neighboring block in the order of the leftmost lowermost block A, the uppermost right block B, and the upper left corner block E. As another example, the encoder and the decoder may be arranged in the order of the leftmost lowermost block A, the uppermost right block B, the upper right corner block C, the lower left corner block D and the upper left corner block E, May be scanned. As another example, the encoder and the decoder may include a leftmost bottom block A, an uppermost right block B, a right upper corner block C, a left lower corner block D, a left upper corner block E, F) and the top leftmost block (G).

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 in the reconstructed neighboring block, and convert the derived intermediate value into L1 temporal motion information . For example, the plurality of blocks may be a left uppermost block F, an uppermost left block G, a right upper corner block C, a left lower corner block D, and a left upper corner block E .

The method of deriving the L1 temporal motion information of the current block from the restored neighboring block is not limited to the above-described embodiment, and the L1 temporal motion information of the current block can be derived in various ways according to implementation and / or necessity.

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

(Xp, yP), an input motion vector (mvLXCol), and an input reference picture number (RefPicOrder (currPic, refIdxLX, LX)) of the upper leftmost sample of the current block may be included in the input for the temporal motion information derivation process have. Here, currPic may mean the current picture. The output of the process may be a motion vector (mvLXCol) used as the last temporal motion information and information (availableFlagLXCol) indicating the presence or absence of the last temporal motion information. Here, X may have a value of 0 or 1. For example, when X is 0, mvLXCol, refIdxLX, LX may represent mvL0Col, refIdxL0, L0, which may refer to variables related to L0 temporal motion information. Also, mvLX may represent a motion vector, mvLX [0] may be a motion vector of the x component, and mvLX [1] may represent a motion vector of the y component. refIdxLX may represent an LX reference picture index indicating a reference picture in the LX reference picture list in which reference pictures are stored. If the refIdxLX value is 0, refIdxLX can indicate the first reference picture in the LX reference picture list. If the refIdxLX value is -1, refIdxLX can indicate that there is no reference picture in the reference picture list. In addition, predFlagLX described later can indicate whether or not motion compensation is performed at the time of generating a prediction block. For example, when the predFlagLX value is 1, the encoder and the decoder can perform motion compensation at the time of generating a prediction block.

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

If the leftmost top block is not a block coded in the intra mode and predFlagL0A is '1' and mvL0A is (0, 0, 1, 0), the encoder and the decoder can perform the following procedure. Here, A may indicate that predFlagL0A and mvL0A are information on the leftmost top block (A).

mvL1Col = mvL0A

Otherwise, if there is an upper leftmost block B (xP, yP-1) adjacent to the upper end of the current block, the uppermost left block is not a block coded in the intra mode, and predFlagL0B is '1' and mvL0B Is not (0, 0), the encoder and the decoder can perform the following procedure. Here, B may indicate that predFlagL0B and mvL0B are information on the upper leftmost block (B).

mvL1Col = mvL0B

Otherwise, if there is a left upper corner block E (xP-1, yP-1) positioned at the upper left corner of the current block and the uppermost left block is not a block coded in the intra mode and predFlagL0E '1' and mvL0E is not (0, 0), the encoder and decoder can perform the following procedure. Here, E may indicate that predFlagL0E and mvL0E are information on the upper leftmost block (E).

mvL1Col = mvL0E

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

avilableFlagL1Col = 0

Then, the encoder and the decoder can perform the following procedure.

availableFlagCol = availableFlagL0Col || availableFlagL1Col

predFlagLXCol = availableFlagLXCol

Here, availableFlagCol indicates whether temporal motion information has been derived, and predFlagLXCol indicates whether or not the temporal temporal motion information for each of L0 temporal motion information and L1 temporal motion information is present.

FIG. 8 is a block diagram schematically showing an embodiment of an inter prediction apparatus capable of performing a temporal motion information derivation process according to the embodiment of FIG. The inter prediction apparatus according to the embodiment of FIG. 8 includes a temporal motion information determination unit 810, a restored neighboring block motion information determination unit 820, a prediction direction information resetting and L0 motion information setting unit 830, And a resetting 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 input temporal motion information, that is, whether the L0 reference picture number and the L1 reference picture number are the same, And the L1 motion vector are the same.

If the L0 temporal motion information and the L1 temporal motion information are not the same, the inter prediction apparatus can use the input temporal motion information as temporal motion information of the current block as it is. If AMVP is applied, the temporal motion information of the current block may be determined or registered as a predicted motion vector candidate for the current block. Also, if a merge is applied, the 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 identical to each other, the restored neighboring block motion information determination unit 820 can perform a determination process.

6, the temporal motion information determination unit 810 determines whether or not the L0 temporal motion information is identical to the L1 temporal motion information, whether or not the L0 reference picture number and the L1 reference picture number are the same, Direction. For example, when the L0 reference picture number and the L1 reference picture number are not the same, the inter prediction apparatus can use the input temporal motion information as it is as the temporal motion information of the current block. If the L0 reference picture number and the L1 reference picture number are The determination process by the restored neighboring block motion information determination unit 820 may be performed. As another example, when the prediction direction of the call block is bidirectional prediction, the inter prediction apparatus can use the input temporal motion information as it is as temporal motion information of the current block, and if the prediction direction of the call block is unidirectional prediction, The determination process by the information determination unit 820 may be performed.

The restored neighboring block motion information determination unit 820 can determine whether motion information of the restored neighboring block exists. If there is no motion information of the restored neighboring block (for example, when there is no block having motion information among the restored neighboring blocks of a predetermined position and / or a position selected by a predetermined method) Reset and L0 motion information setting unit 830 may be used to reset the prediction direction information and to set the L0 motion information. If motion information of the restored neighboring block exists (for example, a block having motion information exists among restored neighboring blocks at a predetermined position and / or a position selected by a predetermined method), the L1 temporal motion The resetting process by the information resetting unit 840 can be performed.

If motion information of the restored neighboring block does not exist, the prediction direction information resetting and L0 motion information setting unit 830 can set the prediction direction information of the current block to unidirectional prediction again. At this time, the prediction direction information resetting and L0 motion information setting unit 830 may set only the L0 temporal motion information among the input temporal motion information as the last temporal motion information of the current block.

If there is motion information of the restored neighboring block, the L1 temporal motion information resetting unit 840 can reset the L1 temporal motion information of the current block to motion information of the restored neighboring block. That is, the inter prediction apparatus can use the motion information of the restored neighboring block as the L1 temporal motion information of the current block. In this case, for example, when the L1 temporal motion information resetting unit 840 searches motion information to be used as L1 temporal motion information of the current block in the restored neighboring block, the motion information having the zero vector (0,0) Only motion information having no zero vector (0, 0) can 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. A specific embodiment of each of the above-described methods has been described above with reference to Figs. 6 and 7, and will not be described here.

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

Although the embodiments described below are described based on temporal motion information, the present invention is not limited thereto. For example, the methods according to the embodiment of FIG. 9 may include not only temporal motion information in the merge mode and / or AMVP mode, but also motion information of the current block derived based on the merge candidate list in the merge mode and / And 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 can be derived based on the motion information of the call block corresponding to the current block in the reconstructed call picture. Here, the call picture may correspond to one picture among the reference pictures included in the reference picture list, for example. The encoder and the decoder can determine a predetermined relative position based on a block existing at a position spatially coincident with the current block in the call picture, and determine the relative position based on the determined relative position (for example, The location of the call block may be derived based on the internal and / or external location of the block in the location). The temporal motion information derived based on the call block may include the prediction direction information, the L0 reference picture number, the L1 reference picture number, the L0 motion vector, and the L1 motion vector.

9, in the temporal motion information derived based on the call block, the encoder and the decoder determine whether the L0 temporal motion information and the L1 temporal motion information are the same, that is, whether the L0 reference picture number and the L1 reference picture number are the same, It may be determined whether the vector and the L1 motion vector are the same (S910). Hereinafter, for the sake of convenience of explanation, the temporal motion information inputted to the step S910 before the temporal motion information resetting is input temporal motion information (L0 input temporal motion information, L1 input temporal motion information) do. The reference picture index included in the input temporal motion information includes an input motion vector (L0 input motion vector and L1 input motion vector), an input reference picture index (L0 input reference picture index, L1 input The reference picture number included in the input temporal motion information is referred to as an input reference picture number (L0 input reference picture number, 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, when the L0 input reference picture number and the L1 input reference picture number are not the same and / or when the L0 input motion vector and the L1 input motion vector are not the same , The encoder and the decoder can use the input temporal motion information derived based on the call block as temporal motion information of the current block as it is. If AMVP is applied, the temporal motion information of the current block may be determined or registered as a predicted motion vector candidate of the current block. Also, when a merge is applied, the temporal motion information of the current block may be determined or registered as a merge candidate of the current block.

If the L0 input temporal motion information and the L1 input temporal motion information are the same, the encoder and the decoder can determine whether 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 the call blocks at a predetermined position and / or a predetermined position.

Hereinafter, the call block used for deriving the input temporal motion information is referred to as a first call block for the sake of convenience of explanation, and it is assumed that the motion information exists or not in the step S920, The call block used for resetting the L1 input temporal motion information is referred to as a second call block in step S940. Further, the call picture including the first call block is called the first call picture, and the call picture including the second call block is called the second call picture. Here, for example, the first call picture and the second call picture may correspond to one picture among the reference pictures included in the reference picture list, respectively.

If motion information of the second call block does not exist (for example, a block having motion information does not exist in a predetermined position and / or a second call block at a position selected by a predetermined method) The prediction direction information of the current block can be set again as unidirectional prediction (S930). Also, at this time, the encoder and the decoder can 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 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), the encoder and the decoder The motion information of the second call block can be used as the last L1 temporal motion information of the current block (S940). That is, at this time, the encoder and the decoder can reset the L1 input temporal motion information of the current block to the motion information of the second call block. Specific embodiments of the second call picture and the second call block used for resetting the L1 input temporal motion information will be described later.

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

Meanwhile, in the above-described embodiment, whether or not to perform the processes of S920 to S940 is determined based on the identity of the L0 input temporal motion information and the L1 input temporal motion information. However, the encoder and the decoder may determine whether to perform the processes of S920 through S940 .

In one embodiment, the encoder and the decoder may determine whether to perform the steps S920 to S940 based on the identities of the L0 input reference picture number and the L1 input reference picture number. For example, the encoder and the decoder may perform steps 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 steps S920 to S940 based on the prediction direction of the first call block. As described above, the prediction direction information may refer to information indicating whether unidirectional prediction is applied to the block on which prediction is performed, or whether bidirectional prediction is applied. Accordingly, the prediction direction may correspond to unidirectional prediction or bidirectional prediction. For example, the encoder and the decoder may perform steps S920 to S940 when the motion information (prediction direction) of the first call block is unidirectional prediction rather than 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 yet another embodiment, the encoder and the decoder may determine whether to perform the steps S920 to S940 based on information on whether motion information is present in the first call block. For example, the encoder and the decoder may perform steps S920 through S940 when motion information does not exist in the first call block. In this case, in step S940, the L0 input temporal motion information other than the L1 input temporal motion information may be reset. That is, the encoder and the decoder can set the L0 input temporal motion information as the motion information of the second call block, and can perform unidirectional prediction for the current block, rather than bidirectional prediction. If there is no motion information in the first call block, the encoder and the decoder may reset both the L0 input temporal motion information and the L1 input temporal motion information in step S940. That is, the encoder and the decoder may reset both the L0 input temporal motion information and the L1 input temporal motion information to motion information of the second call block, and may perform bi-directional prediction on the current block.

In yet another embodiment, the encoder and decoder may determine whether to perform S920 through S940 based on the size of the current block. For 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, 8x8, 16x16, or 32x32. In this case, the encoder and the decoder can perform steps 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 steps 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 the motion vector of the second call block, and as another example, the motion vector (s) May be set as a motion vector of the reconstructed neighboring block. In another example, the motion vector (s) corresponding to the zero vector (0, 0) may be set as a motion vector of a block located in the periphery of the first call block May be set. In another embodiment, the encoder and the decoder may perform steps S920 to S940 when the L0 motion vector and / or the L1 motion vector in the motion information of the first call block do not correspond to the zero vector (0, 0) . 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) ) Can be reset to the motion vector of the second call block.

The conditions for determining whether to perform the steps S920 to S940 are not limited to the above-described embodiments, and various conditions may be applied depending on the conditions and / or the necessity.

In the above-described embodiments, since the L0 input temporal motion information and the L1 input temporal motion information are temporally derived motion information, there is a high possibility that they correspond to motion information due to the movement of the object. Therefore, when the encoder and the decoder search motion information to be used as the last L1 temporal motion information of the current block in the second call block, motion information having a zero vector (0, 0) is not selected and a zero vector (0, 0) May be selected. 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.

On the other hand, the reset final L1 temporal motion information may be the same as the L0 input temporal motion information of the current block. Therefore, when searching for motion information to be used as the last L1 temporal motion information of the current block in the second call block, the encoder and the decoder can select motion information that is not the same as the L0 input temporal motion information. For example, if the last L1 temporal motion information of the current block is derived based on the second call block as in S940, the encoder and the decoder may determine the block having the L0 input temporal motion information and the motion information of the current block, It can be determined as a block used for deriving the final L1 temporal motion information. At this time, 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 value, as motion information to be used as the final L1 temporal motion information. Here, the predetermined threshold may be determined based on mode information of a current block, motion information of a current block, mode information of a neighboring block, motion information of neighboring blocks, or the like, 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 the L0 motion information and the L1 motion information. In this case, the encoder and the decoder can determine one of the L0 motion information and the L1 motion information as motion information to be used as the last L1 temporal motion information of the current block. For example, the encoder and decoder may use the L0 motion information of the second call block as the last L1 temporal motion information for the current block. In this case, when there is no L0 motion information in the second call block, the encoder and the decoder can use the L1 motion information of the second call block as the last L1 temporal motion information for the current block. As another example, the encoder and decoder may use the L1 motion information of the second call block as the last L1 temporal motion information for the current block. In this case, if there is no L1 motion information in the second call block, the encoder and the decoder can use the L0 motion information of the second call block as the last L1 temporal motion information for the current block.

Meanwhile, the encoder and decoder may not use the motion information of the second call block in order to reset the L1 input temporal motion information (for example, the L1 input motion vector) of the current block in step S940. At this time, the encoder and the decoder can reset L1 input temporal motion information (e.g., L1 input motion vector) of the current block based on motion information (e.g., motion vector) of the first call block. Hereinafter, embodiments related thereto will be described, which will be described based on a motion vector.

In one embodiment, the encoder and the decoder are configured to perform, in the first call picture, a motion indicating a relative position shifted based on a predetermined distance and / or a direction at a position indicated by motion information (motion vector) Information can be used as the last L1 temporal motion information (L1 motion vector) of the current block. For example, the encoder and the decoder may divide the vertical and / or horizontal directions by 1/4 pixel size (e.g., (-1,0), (1,0), 1, -1), (1, 1), etc. Here, the 1/4 pixel unit is 1 The motion information indicating the moved position can be used as the last L1 temporal motion information of the current block. As another example, the encoder and the decoder may divide the motion vector of the first call block by a half pixel size (e.g., (-2,0), (2,0), ( (2, -2), (2, 2), etc. Here, the 1/4 pixel unit is 1 The motion information indicating the moved position can be used as the last L1 temporal motion information of the current block. As another example, the encoder and the decoder may calculate the integer pixel size (for example, (-4,0), (4,0), (0), , -4), (0,4), (-4,4), (-4,4), (4,4), (4,4) The motion information indicating the moved position may be used as the last L1 temporal motion information of the current block. On the other hand, since the motion vector includes the vertical direction component and the horizontal direction component, the above-described methods (movement by 1/4 pixel size, movement by 1/2 pixel size, movement by integer pixel size) May be independently applied to each component. At this time, 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 use the changed value as the last L1 temporal motion information (L1 motion vector) of the current block after changing the motion information (motion vector) value of the first call block to a value of another pixel unit have. For example, when the motion information value of the first call block is a value of a quarter pixel unit, the encoder and the decoder change the motion information value of the first call block to a value of a half pixel unit based on a shift operation or the like And may use the changed value as the last 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 a half-pixel unit, the encoder and the decoder can change the motion information value of the first call block to a value of an integer pixel unit based on a shift operation or the like , And use the changed value as the last L1 temporal motion information of the current block.

The method of resetting the L1 input temporal motion information (for example, the L1 input motion vector) of the current block based on the motion information of the first call block (for example, the motion vector) is not limited to the above- And / or may be applied in various forms as needed. Also, the methods according to the above-described embodiments can be applied in the same or similar manner when the L1 input temporal motion information is reset based on the motion information of the second call block as in step S940 of FIG.

Meanwhile, in the above-described embodiment, the input temporal motion information input to the 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 temporally derived motion vectors based on the first call block, and the L0 input reference picture index and the L1 input reference picture index may be obtained from the restored neighboring blocks May be a spatially derived reference picture index. At this time, the L0 input reference picture index and the L1 input reference picture index can be set to the smallest value, not a negative number, in the reference picture index of the restored neighboring block. On the other hand, 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 restored neighboring block.

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

In one embodiment, the encoder and decoder may reset the L1 input reference picture index based on the second call block. As described above, the encoder and the decoder can use the motion information of the second call block as the last L1 temporal motion information of the current block. At this time, the encoder and the decoder can 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 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 (e.g., L0 input motion vector, L0 input reference picture index, etc.) and L1 input temporal motion information (e.g., L1 input motion vector, L1 input reference picture index, ) Are the same, 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 it as 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 of the L0 reference picture index and the L1 reference picture index are zero.

In yet another embodiment, the encoder and decoder may reset the L1 input reference picture index value to the same value as the L0 input reference picture index value. On the other hand, the encoder and decoder may reset the L1 input reference picture index value to a reference picture index value not equal to the L0 input reference picture index. There may be a reference picture index that is not the same as the L0 input reference picture index in the reference picture index of the restored neighboring block. In this case, for example, the encoder and the decoder may use the most frequently used reference picture index among the reference picture indexes which are not the same as the L0 input reference picture index, in order to reset the L1 input reference picture index. As another example, the encoder and decoder may use a reference picture index having the smallest non-negative reference picture index, which is not the same as the L0 input reference picture index, for resetting the L1 input reference picture index.

Meanwhile, as described above, the encoder and the decoder can 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 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 a final L1 reference picture index without resetting, or may be used as a final L1 reference picture index through a reset process as in the above embodiment. At this time, the reference picture corresponding to the motion vector of the second call 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 call block and use the scaled motion vector as the last L1 temporal motion vector of the current block.

The above-described embodiments may be applied in various ways in accordance with the process of resetting the motion vector and the process of resetting the reference picture index (e.g., 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 can use the first call picture used for deriving the L0 input temporal motion information as it is as the second call picture, and the second call block can be derived from the second call picture. At this time, the encoder and the decoder may use the motion vector of the second call block by scaling to reset the L1 input motion vector. In this case, the scaled motion vector may be used as the last L1 temporal motion information. In this case, for example, the L1 input reference picture index can be used as final L1 temporal motion information without resetting. That is, the encoder and the decoder can assign 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 can assign a predetermined fixed reference picture index value to the L1 temporal motion information of the current block, and the predetermined fixed reference picture index can be used as the last 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 they are, as the second call picture, as in the above embodiment, and the second call block may use the second call picture Lt; / RTI > In this case, 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 call block, 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 the last L1 temporal motion information. In this case, for example, the L1 input reference picture index can be used as final L1 temporal motion information without resetting. That is, the encoder and the decoder can assign 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 can assign a predetermined fixed reference picture index value to the L1 temporal motion information of the current block, and the predetermined fixed reference picture index can be used as the last 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 the most recently decoded reference picture among the reference pictures in the L1 reference picture list which is not the same as the first call picture, for example. As another example, the encoder and the decoder may select a reference picture having the highest frequency of use as the second call picture based on the reference picture number of the restored neighboring block. The second call block may be derived from the second call picture, wherein the encoder and the decoder may use a motion vector of the second call block for scaling the L1 input motion vector. In this case, the scaled motion vector may be used as the last L1 temporal motion information. In this case, for example, the L1 input reference picture index can be used as final L1 temporal motion information without resetting. That is, the encoder and the decoder can assign 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 can assign a predetermined fixed reference picture index value to the L1 temporal motion information of the current block, and the predetermined fixed reference picture index can be used as the last L1 temporal motion information.

In another embodiment, the encoder and 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 a second call picture, as in the above embodiment, May be derived from the second call picture. Here, the second call picture may be the most recently decoded reference picture among the reference pictures in the L1 reference picture list which is not the same as the first call picture, for example. As another example, the encoder and the decoder may select a reference picture having the highest frequency of use as the second call picture based on the reference picture number of the restored neighboring block. In this case, 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 call block, 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 the last L1 temporal motion information. In this case, for example, the L1 input reference picture index can be used as final L1 temporal motion information without resetting. That is, the encoder and the decoder can assign 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 can assign a predetermined fixed reference picture index value to the L1 temporal motion information of the current block, and the predetermined fixed reference picture index can be used as the last L1 temporal motion information.

The combination of embodiments of the process of resetting the motion vector and the process of resetting the reference picture index is not limited to the above-described embodiment, and various combinations of the embodiments described above and / have.

On the other hand, 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 decoder may set the prediction direction information of the current block back to unidirectional prediction. At this time, the encoder and the decoder can use only L0 temporal motion information as temporal motion information of the current block. This method may be applied to the present invention as a combination with the above-described embodiments.

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

The encoder and the decoder can determine the second call block based on the co-located block existing spatially in the same position as the current block in the second call picture. In FIG. 10, block 1010 represents the current block, and block 1020 represents the co-location block in the second call picture. Here, the second call picture may be determined in various manners.

In one embodiment, the encoder and the decoder can determine one reference picture among the reference pictures included in the L0 reference picture list as the second call picture. For example, the encoder and the decoder can determine the first reference picture in the L0 reference picture list as the second call picture. As another example, the encoder and 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 can 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 among the reference pictures included in the L1 reference picture list as the second call picture. For example, the encoder and the decoder can 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 the decoder may use a reference picture providing 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 It can be used as a second call picture. Here, the coding 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. At this time, the encoder can derive the second call picture based on the coding efficiency, and can transmit the 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-described 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 which is not the same as the first call picture can be used for deriving the last 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 a different manner depending on implementation and / or necessity.

10, a block located at the center inside the co-located block 1020 is referred to as a block D, a block located at the upper left corner inside the co-located block 1020 is referred to as a block S, A block located at the lower left corner of the co-located block 1020 is referred to as a block Q, a block located at the upper right corner inside the co-located block 1020 is referred to as a block R, and a block located at the lower right corner inside the co- Among the blocks adjacent to the left side of the co-located block 1020, the block located at the uppermost position is the block F, the block located at the lower most position among the blocks adjacent to the left side of the co- located block 1020 is the block J, A block located at the leftmost of the blocks adjacent to the top of the co-located block 1020 is referred to as a block G, a block located at the rightmost of the blocks adjacent to the top of the co-located block 1020 is referred to as a block M, A block located at the bottom of the block adjacent to the right of the co-located block 1020 is referred to as a block B, and a block located at the leftmost of the blocks adjacent to the bottom of the co-located block 1020 is referred to as a block K, The block located at the rightmost position among the blocks adjacent to the lower end of the position block 1020 is referred to as a block A. [ A block located at the upper left corner outside the co-located block 1020 is referred to as a block E, a block located at the lower left corner outside the co-located block 1020 is referred to as a block I, The block located at the lower right corner outside the block L and the block 1020 located at the same location block 1020 is referred to as a block H. A block located adjacent to the right side of the block B is referred to as a block P, and a block located adjacent to a lower end of the block A is referred to as a block O. [

9, the encoder and the decoder can use the motion information of the second call block as the last L1 temporal motion information of the current block according to a predetermined condition. That is, the encoder and the decoder can reset the L1 input temporal motion information value to the motion information value of the second call block. At this time, the motion used as the second call block and / or the last L1 temporal motion information may be derived in various ways.

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

In another embodiment, the encoder and the decoder may scan a plurality of blocks existing at a predetermined position among the blocks located inside and / or outside the co-located block 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 last L1 temporal motion information of the current block. Here, the first block in which the motion information exists may correspond to the second call block. The scan target block and the scan order can be set in various forms. For example, the encoder and decoder can scan blocks in 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, Can be used as the last 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 the L1 temporal motion information of the current block from the second call block is not limited to the above-described embodiment, and the L1 temporal motion information of the current block can be derived in various ways according to implementation and / or necessity.

11 is a block diagram schematically showing an embodiment of an inter prediction apparatus capable of performing a temporal motion information derivation process according to the embodiment of FIG. The inter prediction apparatus according to the embodiment of FIG. 11 includes a temporal motion information determination unit 1110, a second call block motion information determination unit 1120, a prediction direction information reset and L0 motion information setting unit 1130, May include a resetting unit 1140.

Referring to FIG. 11, the temporal motion information determination unit 1110 determines whether the L0 input temporal motion information and the L1 input temporal motion information are the same in input temporal motion information, that is, whether the L0 input reference picture number and the L1 input reference picture number are the same And determine whether the L0 input motion vector and the L1 input motion vector are the same.

If the L0 input temporal motion information and the L1 input temporal motion information are not the same, the inter prediction apparatus can use the input temporal motion information as temporal motion information of the current block as it is. If AMVP is applied, the temporal motion information of the current block may be determined or registered as a predicted motion vector candidate for the current block. Also, if a merge is applied, the temporal motion information of the current block may be determined or registered as a merge candidate for the current block. If 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 determination unit 1120 may be performed.

9, the temporal motion information determination unit 1110 determines whether the L0 input temporal motion information and the L1 temporal temporal motion information are identical or not, whether the L0 input reference picture number and the L1 input reference picture number are identical or not, 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 can use the input temporal motion information as it is as the temporal motion information of the current block. The L0 input reference picture number and the L1 input reference picture number If the reference picture numbers are the same, the determination process by the second call block motion information determination unit 1120 can be performed. As another example, when the prediction direction of the first call block is bidirectional prediction, the inter prediction device can use the input temporal motion information as it is as the temporal motion information of the current block. If the prediction direction of the first call block is unidirectional prediction 2 call block motion information determination unit 1120 may be performed.

The second call block motion information determination unit 1120 can determine whether motion information of the second call block exists. When motion information of the second call block does not exist (for example, a block having motion information does not exist in a predetermined position and / or a second call block at a position selected by a predetermined method) Reset and the L0 motion information setting unit 1130 can perform the process of setting the prediction direction information and setting the L0 motion information. When there is motion information of the second call block (for example, 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), the L1 temporal motion The resetting process by the information resetting unit 1140 can be performed.

When there is no motion information of the second call block, the prediction direction information resetting and L0 motion information setting unit 1130 can set the prediction direction information of the current block to unidirectional prediction again. In this case, the prediction direction information resetting and L0 motion information setting unit 1130 may set only the L0 input temporal motion information among the input temporal motion information as the last temporal motion information of the current block.

If the motion information of the second call block exists, the L1 temporal motion information resetting unit 1140 can 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 can use the motion information of the second call block as the last L1 temporal motion information of the current block. In this case, when the motion information of the second call block includes a zero vector (0, 0), the L1 temporal motion information resetting unit 1140 resets the motion information of the block located around the second call block to the final It can also be used as L1 temporal motion information. A specific embodiment of each of the above-described methods has been described above with reference to Figs. 6 and 7, and will not be described here.

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

As described above, the encoder and the decoder can derive the motion information of the current block based on the motion information of the restored neighboring block and / or the motion information of the call block. 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, the reconstructed neighboring block being a block in the current picture reconstructed by decoding and / or decoding. Also, the call block may refer to a block corresponding to the current block in the call picture, and the call picture may correspond to one picture among the reference pictures in the reference picture list, for example. In this case, the motion information derived from the restored 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. Here, the spatial motion information and the temporal motion information may include prediction direction information, an L0 reference picture number, an L1 reference picture number, an L0 motion vector, and an L1 motion vector, respectively.

On the other hand, in the image decoding process, there may exist a picture which is not decoded among the previous pictures of the current picture (and / or the decoding target picture) due to excessive traffic of the network. In this case, the erroneous call block may be used in deriving the temporal motion information for the block in the current picture, and accurate temporal motion information may not be derived, so that the current picture may not be decoded properly. In order to solve the above problem, the encoder and the decoder derive 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, Based on time. That is, the encoder and the decoder can independently set L0 motion information and L1 motion information, respectively. In this case, even if there is a previous picture that has not been decoded, the encoder and the decoder can restore the current picture to some extent.

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

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

In one embodiment, when the L0 motion information is temporally derived motion information based on a call block, the encoder and the decoder may use the spatial motion information derived based on the restored neighboring blocks as L1 motion information. In another embodiment, when the L0 motion information is spatially derived motion information based on the reconstructed neighboring block, the encoder and the decoder may use the 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, the L0 motion information is assumed to be motion information derived based on a call block. In this case, as described above, the encoder and the decoder can use spatial motion information spatially derived based on the restored neighboring blocks as L1 motion information. In this case, for example, the encoder and the decoder can derive only the same or similar motion information as the L0 motion information as the spatial motion information to be used as the L1 motion information. Alternatively, 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. At this time, 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 value as the spatial motion hypothesis to be used as the L1 motion information. Here, the predetermined threshold may be determined based on mode information of a current block, motion information of a current block, mode information of a neighboring block, motion information of neighboring blocks, or the like, and may be determined in various ways.

The method of setting the L0 motion information and the L1 motion information is not limited to the above-described embodiment, and may vary depending on implementation and / or necessity.

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

Referring again 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 the same. Therefore, when the L0 motion information and the L1 motion information are the same, the encoder and the decoder can set the prediction direction information of the current block back to unidirectional prediction. At this time, the encoder and the decoder can use only L0 motion information as motion information of the current block.

13 is a block diagram schematically showing an embodiment of an inter prediction apparatus capable of performing a motion information derivation process 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 in the embodiment of FIG. 12, the encoder and the decoder can independently set L0 motion information and L1 motion information, respectively. At this time, one of the L0 motion information and the L1 motion information can be extracted spatially based on the reconstructed neighboring block and the other based on the call block, in the encoder and the decoder.

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

Referring again 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 motion information (spatial motion information) spatially derived based on the restored neighboring blocks as L1 motion information, or temporally derived motion information (temporal motion information) based on the call block, Can be used as the L1 motion information. That is, the L1 motion information may be spatially derived based on the reconstructed neighboring blocks, or temporally derived based on the call block.

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, and thus will not be described here.

13, the motion information integrating unit 1330 integrates the L0 motion information set in the L0 motion information setting unit 1310 and the L1 motion information set in the L1 motion information setting unit 1320, Information can be derived.

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

Although the embodiments described below are described based on temporal motion information, the present invention is not limited thereto. For example, the methods according to the embodiment of FIG. 14 may include not only temporal motion information in the merge mode and / or the AMVP mode, but also motion information of the current block derived based on the merge candidate list in the merge mode and / And 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 can be derived based on the motion information of the call block corresponding to the current block in the reconstructed call picture. Here, the call picture may correspond to one picture among the reference pictures included in the reference picture list, for example. The encoder and the decoder can determine a predetermined relative position based on a block existing at a position spatially coincident with the current block in the call picture, and determine the relative position based on the determined relative position (for example, The location of the call block may be derived based on the internal and / or external location of the block in the location). The temporal motion information derived based on the call block may include the prediction direction information, the L0 reference picture number, the L1 reference picture number, the L0 motion vector, and the L1 motion vector.

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

Hereinafter, for the sake of convenience of explanation, the temporal motion information inputted to the step S1410 before the temporal motion information resetting is input temporal motion information (L0 input temporal motion information, L1 input temporal motion information) do. In this case, the input temporal motion information may correspond to temporal motion information derived based on the call block. The reference picture index included in the input temporal motion information includes an input motion vector (L0 input motion vector and L1 input motion vector), an input reference picture index (L0 input reference picture index, L1 input The reference picture number included in the input temporal motion information is referred to as an input reference picture number (L0 input reference picture number, L1 input reference picture number). In the following embodiments, the reference picture indicated by the L0 input reference picture number is referred to as the L0 reference picture, and the reference picture indicated by the L1 input reference picture number is referred to as the 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 input temporal motion information derived based on the call block can be directly used as the temporal temporal motion information of the current block. If AMVP is applied, the final temporal motion information may be determined or registered as a predicted motion vector candidate of the current block. Also, if a merge is applied, the final temporal motion information may be determined or registered as a merge candidate of the current block.

If the L0 input temporal motion information and the L1 input temporal motion information are the same, the encoder and the decoder may search for or derive 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, the L1 reference picture can correspond to the same picture as the L0 reference picture. Therefore, in the embodiment described later, the L1 reference picture can mean the same picture as the L0 reference picture.

For example, the encoder and the decoder can 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 the motion information from the L1 reference picture by a predetermined method, and then transmit the derived motion information to the decoder by including it in the bitstream. At this time, the decoder can determine motion information to be used as the last 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. At this time, the encoder may obtain the difference value between the 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 again to FIG. 14, the encoder and the decoder can use the motion information derived from the L1 reference picture as the last L1 temporal motion information of the current block (S1430). That is, at this time, the encoder and the decoder can 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 for deriving motion information to be used as the last L1 temporal motion information in the L1 reference picture will be described.

In one embodiment, the encoder and the decoder decode motion information indicating a position existing within a predetermined range centered on a position indicated by L0 input temporal motion information (motion vector) in the L1 reference picture as final L1 temporal motion information (L1 motion vector). Specifically, the predetermined range corresponds to a range including a position within the + T and / or -T distance in the vertical and / or horizontal directions about the position indicated by the L0 input temporal motion information in the L1 reference picture . Here, for example, T may be a value indicating a distance of a quarter pixel unit, and in another example, T may be a value representing a distance of a half pixel unit. As another example, T may be a value indicating a distance in integer pixel units. When an integer pixel unit is used, the interpolation process may not be performed at the time of motion compensation, so that the calculation complexity can be reduced.

As another example, the encoder can derive, in the L1 reference picture, the best matching or similar area with the input block (original block) corresponding to the current block. At this time, the encoder can derive motion information to be used as the last L1 temporal motion information of the current block based on the derived area. For example, the encoder can derive a motion vector to be used as the last L1 temporal motion information based on the position of the block corresponding to the derived area and the position of the current block, and based on the block corresponding to the derived area, The reference picture index (and / or the reference picture number) to be used as the L1 temporal motion information can 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 can reset the L1 input temporal motion information based on the transmitted motion information.

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

The method of deriving the motion information to be used as the last 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 according to implementation and / .

Meanwhile, in the above-described embodiment, it is determined whether to perform the processes of S1420 to S1430 based on the identity of the L0 input temporal motion information and the L1 input temporal motion information. However, the encoder and the decoder may determine whether to perform the processes of S1420 through S1430 .

In one embodiment, the encoder and the decoder may determine whether to perform the steps S1420 to S1430 based on the prediction direction of the call block. As described above, the prediction direction information may refer to information indicating whether unidirectional prediction is applied to the block on which prediction is performed, or whether bidirectional prediction is applied. Accordingly, the prediction direction may correspond to unidirectional prediction or bidirectional prediction. For example, the encoder and decoder may perform steps S1420 to S1430 when motion information (prediction direction) of the call block is unidirectional prediction rather than 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 process of S1420 to S1430 based on information on whether motion information is present in the call block. For example, the encoder and the decoder may perform steps S1420 through S1430 when there is no motion information in the call block. In this case, in step S1430, L0 input temporal motion information other than the L1 input temporal motion information may be reset. That is, the encoder and the decoder can reset the L0 input temporal motion information to the motion information of the L1 reference picture, and can perform unidirectional prediction for the current block, rather than bidirectional prediction. If the motion information does not exist in the call block, the encoder and the decoder may reset both the L0 input temporal motion information and the L1 input temporal motion information in step S1430. That is, the encoder and the decoder may reset the L0 input temporal motion information and the L1 input temporal motion information to 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 steps 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 the L1 reference picture, and as another example, the motion vector May be set as a motion vector of the reconstructed neighboring block, or 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 in the periphery of the call block have. In another embodiment, the encoder and the decoder may perform steps 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 call 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) ) Can be reset to the motion vector of the L1 reference picture.

The conditions for determining whether to perform the processes of S1420 to S1430 are not limited to the above-described embodiments, and various conditions may be applied depending on the conditions and / or the necessity.

On the other hand, the motion information derived from the L1 reference picture may be the same as the L0 input temporal motion information of the current block. Accordingly, when searching for motion information to be used as the last L1 temporal motion information of the current block in the L1 reference picture, the encoder and the decoder may find only motion information that is not the same as the L0 input temporal motion information. For example, if the last L1 temporal motion information of the current block is derived based on the L1 reference picture as in S1430, the encoder and the decoder may determine only the Ll input temporal motion information and the other motion information of the current block as the final L1 temporal motion information . At this time, 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 value, as motion information to be used as the final L1 temporal motion information. Here, the predetermined threshold may be determined based on mode information of a current block, motion information of a current block, mode information of a neighboring block, motion information of neighboring blocks, or the like, and may be determined in various ways.

The input temporal motion information input to step S1410 in the above embodiment may include an input motion vector as well as an input reference picture index. Here, the L0 input motion vector and the L1 input motion vector may be temporally derived motion vectors based on the call block, and the L0 input reference picture index and the L1 input reference picture index may be spatially And may be a derived reference picture index. At this time, the L0 input reference picture index and the L1 input reference picture index can be set to the smallest value, not a negative number, in the reference picture index of the restored neighboring block. On the other hand, 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 restored neighboring block.

If the L1 input motion vector is reset based on the L1 reference picture, the reset process can also be performed on the input reference picture index. As an example, the input reference picture index can be reset based on the reference picture index derived from the L1 reference picture as described above. As another example, when L0 input temporal motion information (e.g., L0 input motion vector, L0 input reference picture index, etc.) and L1 input temporal motion information (e.g., L1 input motion vector, L1 input reference picture index, , 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 as 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 of the L0 reference picture index and the L1 reference picture index are zero.

Meanwhile, as described above, the encoder and the decoder can 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 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 a final L1 reference picture index without resetting, or may be used as a final L1 reference picture index through a reset process as in the above embodiment. At this time, 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 last L1 temporal motion vector of the current block.

Also, 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 decoder may set the prediction direction information of the current block back to unidirectional prediction. At this time, the encoder and the decoder can use only L0 temporal motion information as temporal motion information of the current block. This method can be applied to the present invention as a combination with the above-described embodiments.

15 is a block diagram schematically showing an embodiment of an inter prediction apparatus capable of performing a temporal motion information derivation process according to the embodiment of FIG. The inter prediction apparatus according to the embodiment of FIG. 15 may include a temporal motion information determination unit 1510, a motion prediction unit 1520, and an L1 temporal motion information resetting unit 1530.

As described above, the temporal motion information can be derived based on the motion information of the call block corresponding to the current block in the reconstructed call picture. Here, the call picture may correspond to one picture among the reference pictures included in the reference picture list, for example. The encoder and the decoder can determine a predetermined relative position based on a block existing at a position spatially coincident with the current block in the call picture, and determine the relative position based on the determined relative position (for example, The location of the call block may be derived based on the internal and / or external location of the block in the location). The temporal motion information derived based on the call block may include the prediction direction information, the L0 reference picture number, the L1 reference picture number, the L0 motion vector, and the L1 motion vector.

Referring to FIG. 15, the temporal motion information determination unit 1510 determines whether or not the L0 input temporal motion information and the L1 input temporal motion information are the same in input temporal motion information, that is, L0 input reference picture number and L1 It is possible to judge whether or not the input reference picture number is the same and the L0 input motion vector and the L1 input motion vector are the same.

If the L0 input temporal motion information and the L1 input temporal motion information are not the same, the inter prediction apparatus can use the input temporal motion information as temporal motion information of the current block as it is. If AMVP is applied, the temporal motion information of the current block may be determined or registered as a predicted motion vector candidate for the current block. Also, if a merge is applied, the temporal motion information of the current block may be determined or registered as a merge candidate for the current block. If the L0 input temporal motion information and the L1 input temporal motion information are the same, the process by the motion predicting unit 1520 can be performed.

Meanwhile, the temporal motion information determination unit 1510 determines whether or not the L0 input temporal motion information and the L1 input temporal motion information are identical or not, 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 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 can be used as the temporal motion information of the current block as it is. When the L0 input reference picture number and the L1 input reference picture number are The process by the motion predicting unit 1520 can be performed. As another example, when the prediction direction of the call block is bi-directional prediction, the input temporal motion information may be used as the temporal motion information of the current block as it is. If the prediction direction of the call block is unidirectional prediction, May be performed.

Referring again to FIG. 15, when the L0 input temporal motion information and the L1 input temporal motion information are the same, the motion predicting unit 1520 can search for or derive motion information to be used as the last L1 temporal motion information in the L1 reference picture.

In one embodiment, the motion predicting unit 1520 may derive, in the L1 reference picture, the best matching or similar area with the input block (original block) corresponding to the current block. At this time, the motion predicting unit 1520 can derive motion information to be used as the last L1 temporal motion information of the current block based on the derived region. For example, the motion predicting unit 1520 may derive a motion vector to be used as the last L1 temporal motion information based on the position of the block corresponding to the derived area and the position of the current block, The reference picture index (and / or the reference picture number) to be used as the last L1 temporal motion information can be derived based on the block.

On the other hand, when the motion estimator 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 motion information 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. At this time, the encoder may obtain the difference value between the 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 motion information to be used as the last L1 temporal motion information based on the transmitted motion information. That is, when the motion estimator 1520 corresponds to a component of the decoder, the motion estimator 1520 estimates the motion of the current frame based on motion information (e.g., motion information transmitted from the encoder) The motion information to be used as the L1 temporal motion information can be determined.

Referring again to FIG. 15, the L1 temporal motion information resetting unit 1530 can use the motion information derived from the L1 reference picture as the last L1 temporal motion information of the current block. In this case, the L1 temporal motion information resetting unit 1530 may reset the L1 input temporal motion information value to the value of the motion information derived from the motion predicting unit 1520 (motion information derived from the L1 reference picture) .

The embodiments of FIGS. 6 to 15 may be applied individually, but may be applied in various ways depending on the coding mode of each block. In the following embodiments, a block in which the encoding mode is the merge mode is referred to as a merge block. A block other than the merge block may have a block in which the encoding mode is the AMVP mode, for example. Also, in the following embodiments, the current block may correspond to one of a merge block or a non-merge block.

In one embodiment, the temporal motion information derivation method according to the embodiment of FIGS. 6 to 8 is applied to the merged block, and the motion information derivation method according to FIGS. 12 and 13 can be applied to the non-merged block. In this case, if the L0 input temporal motion information and the L1 input temporal motion information are the same in the merging block, the motion information of the restored neighboring block can be used as the last L1 temporal motion information of the current block. In a block other than the merged 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 embodiment of FIGS. 9 to 11 is applied to the merged block, and the temporal motion information derivation method according to FIGS. 14 and 15 is applied to the non-merged block. In this case, when the L0 input temporal motion information and the L1 input temporal motion information are the same in the merging block, the motion information of the newly derived call block, which is not the call block used for deriving the input temporal motion information, . In a block other than the merged block, if the L0 input temporal motion information and the L1 input temporal motion information are the same, the motion information of the L1 reference picture can be used as the last L1 temporal motion information of the current block.

In another embodiment, the temporal motion information derivation method according to the embodiment of FIGS. 6 to 8 is applied to the merged block, and the temporal motion information derivation method according to FIGS. 14 and 15 is applied to the non-merged block. In this case, if the L0 input temporal motion information and the L1 input temporal motion information are the same in the merging block, the motion information of the restored neighboring block can be used as the last L1 temporal motion information of the current block. In a block other than the merged block, if the L0 input temporal motion information and the L1 input temporal motion information are the same, the motion information of the L1 reference picture can be used as the last 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 embodiments, and various combinations of the embodiments and / or the above-described embodiments may be provided as necessary.

In the above-described embodiments, the methods are described on the basis of a flowchart as a series of steps or blocks, but the present invention is not limited to the order of the steps, and some steps may occur in different orders or simultaneously . It will also be understood by those skilled in the art that the steps depicted in the flowchart illustrations are not exclusive and that other steps may be included or that one or more steps in the flowchart may be deleted without affecting the scope of the 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 (3)

Determining a call picture of a current block based on call picture information transmitted from an encoder; Here, the call picture information is information for specifying a picture determined as a call picture of the current block among the reference pictures in the reference picture list,
Deriving a temporal motion vector based on a motion vector of a call block corresponding to the current block in the call picture; Here, the call block is determined according to any one of a first block including a position of a right-bottom pixel of a current block or a second block including a center position of the current block,
Generating a predicted motion vector candidate list for the current block using the temporal motion vector;
Deriving a motion vector of the current block based on the predicted motion vector candidate list; And
And performing motion compensation on the current block based on the derived motion vector. Deriving a motion vector of a current block;
Generating a prediction block corresponding to the current block by performing motion compensation on the current block based on the derived motion vector;
Determining a call picture of the current block;
Deriving a temporal motion vector based on a motion vector of a call block corresponding to the current block in the call picture; Here, the call block is determined according to any one of a first block including a position of a right-bottom pixel of a current block or a second block including a center position of the current block,
Generating a predicted motion vector candidate list for the current block using the temporal motion vector; And
And encoding the call picture information for the call picture,
Wherein the call picture information is information for specifying a picture determined by the call picture of the current block among the reference pictures in the reference picture list. There is provided a computer-readable recording medium for storing a bitstream received by an image decoding apparatus and used for reconstructing a current block included in an image,
Wherein the bitstream comprises call picture information,
The call picture information is used for determining a call picture of the current block and is information for specifying a picture determined as a call picture of the current block among the reference pictures in the reference picture list,
Wherein the call picture is used to derive a temporal motion vector based on a motion vector of a call block corresponding to the current block in the call picture,
Wherein the call block is determined according to any one of a first block including a position of a right-bottom pixel of the current block or a second block including a center position of the current block,
Wherein the temporal motion vector is used to generate a predicted motion vector candidate list for the current block,
The predicted motion vector candidate list is used to derive a motion vector of the current block,
Wherein the motion vector of the current block is used to perform motion compensation on the current block.

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