KR102094436B1 - Method for inter prediction and apparatus thereof - Google Patents

Abstract

The video decoding apparatus according to the present invention is a motion prediction unit that derives motion information of a current block as motion information including L0 motion information and L1 motion information, based on at least one of L0 motion information and L1 motion information, to the current block. It includes a motion compensation unit to generate a prediction block corresponding to the current block by performing motion compensation on the current block, and a restoration block generation unit to generate a restoration block corresponding to the current block based on the prediction block. According to the present invention, image encoding efficiency can be improved.

Description

METHOD FOR INTER PREDICTION AND APPARATUS THEREOF}

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

Recently, as broadcast services having high definition (HD) resolution have been expanded not only in Korea but also worldwide, many users are accustomed to high-resolution and high-definition video, and accordingly, many organizations are accelerating the development of next-generation video devices. In addition, with the increasing interest in UHD (Ultra High Definition), which has a resolution of 4 times higher than that of HDTV, there is a need for a compression technology for higher resolution and higher quality images.

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

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

Another technical problem of the present invention is to provide an image decoding method and apparatus capable of improving image encoding efficiency.

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

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

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

One embodiment of the present invention is an image decoding device. The apparatus is a motion prediction unit for deriving motion information of a current block as motion information including L0 motion information and L1 motion information, and a motion for the current block based on at least one of the L0 motion information and the L1 motion information A motion compensation unit generating a prediction block corresponding to the current block by performing compensation, and a restoration block generation unit generating a restoration block corresponding to the current block based on the prediction block, wherein the motion compensation unit includes: The motion compensation is performed based on whether the L0 motion information and the L1 motion information are identical.

The L0 motion information includes an L0 motion vector and an L0 reference picture number, and the L0 reference picture number indicates a picture order count (POC) assigned to the L0 reference picture, and the L1 motion information refers to the L1 motion vector and L1. A picture number may be included, and the L1 reference picture number may indicate a picture order count (POC) assigned to the L1 reference picture.

When the L0 motion vector and the L1 motion vector are the same, and the L0 reference picture number and the L1 reference picture number are the same, the motion compensation unit, based on the L0 motion information among the L0 motion information and the L1 motion information Uni prediction can be performed.

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

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

When the size of the current block is smaller than a predetermined size, the motion 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.

Another embodiment of the present invention is an image decoding apparatus. The apparatus includes a motion prediction unit that derives motion information from an already reconstructed picture, a motion compensation unit that generates a prediction block corresponding to the current block based on the derived motion information, and the current block based on the prediction block. And a reconstruction block generator for generating a corresponding reconstruction block, wherein the motion information includes a motion vector and a reference picture index, and the motion predictor sets the reference picture index to 0, and the In the reconstructed picture, the motion vector is derived based on a call block corresponding to the current block.

The encoding 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, so that the current block A prediction block corresponding to may be generated.

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

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

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

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

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

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

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In describing the embodiments of the present specification, when it is determined that detailed descriptions of related known configurations or functions may obscure the subject matter of the present specification, detailed descriptions thereof will be omitted.

When a component is said to be “connected” to or “connected to” another component, it is understood that other components may be directly connected or connected to other components, but other components may exist in the middle. It should be. In addition, in the present invention, the description of “including” a specific configuration does not exclude a configuration other than the corresponding configuration, and means that an additional configuration may be included in the scope of the present invention or the technical spirit of the present invention.

Terms such as first and second 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 other components. For example, the first component may be referred to as a second component without departing from the scope of the present invention, and similarly, the second component may be referred to as a first component.

In addition, the components shown in the embodiments of the present invention are shown independently to indicate different characteristic functions, and do not mean that each component is composed of separate hardware or one software component. That is, for convenience of description, each component is listed and included as each component, and at least two components of each component are combined to form one component, or one component is divided into a plurality of components to perform functions. The integrated and separated embodiments of the components are also included in the scope of the present invention without departing from the essence of the present invention.

Also, some of the components are not essential components for performing essential functions in the present invention, but may be optional components for improving performance. The present invention can be implemented by including only components essential for realizing the essence of the present invention, except components used for performance improvement, and structures including only essential components excluding optional components used for performance improvement. Also included in the scope of the present invention.

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

Referring to FIG. 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, and a conversion unit 130 , A quantization unit 140, an entropy encoding unit 150, an inverse quantization unit 160, an inverse transform 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 bitstream. Intra prediction means intra prediction, and inter prediction means inter prediction. In the intra mode, the switch 115 may be switched to intra, and in the inter mode, the switch 115 may be switched to inter. The image encoding apparatus 100 may generate a prediction block for an input block of the input image, and then encode a residual between the input block and the prediction block.

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

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

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

The entropy encoding unit 150 performs entropy encoding based on values (eg, quantized coefficients) calculated by the quantization unit 140 and / or encoding parameter values calculated during an encoding process, and performs bitstream ( bit stream).

When entropy encoding is applied, a small number of bits are allocated to a symbol having a high probability of occurrence, and a number of bits are allocated to a symbol having a low probability of occurrence, thereby representing a symbol. The size of the heat can be reduced. Therefore, compression performance of image encoding may be increased through entropy encoding. The entropy encoding unit 150 may use encoding methods such as exponential golomb (CAVLC), 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 prediction encoding, the currently encoded image needs to be decoded and stored to be used as a reference image. Therefore, the quantized coefficients are inversely quantized by the inverse quantization unit 160 and inversely transformed by the inverse transformation unit 170. The inverse quantized and inverse transformed coefficients are added to the prediction block through the adder 175 and a reconstructed 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, SAO (Sample Adaptive Offset), and ALF (Adaptive Loop Filter) to the restoration block or restoration picture. can do. The filter unit 180 may also be referred to as an adaptive in-loop filter. The deblocking filter may remove block distortion and / or blocking artifacts that occur at the boundary between blocks. SAO can add an appropriate offset value to a pixel value to compensate for a coding error. ALF may perform filtering based on a value obtained by comparing the reconstructed image with the original image, or may be performed only when high efficiency is applied. The reconstructed block that has passed through the filter unit 180 may be stored in the reference picture buffer 190.

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

* Referring to FIG. 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, and an adder (255), a filter unit 260 and a reference picture buffer 270.

The image decoding apparatus 200 may receive the bitstream output from the encoder, perform decoding in intra mode or inter mode, and output a reconstructed image, that is, a reconstructed image. In the case of intra mode, the switch is switched to intra, and in the case of inter mode, the switch can be switched to inter. The image decoding apparatus 200 may obtain a residual block from the received bitstream, generate a prediction block, and then add a residual block and a prediction block to generate a reconstructed block, that is, a reconstructed block.

The entropy decoding unit 210 may entropy decode the input bitstream according to a probability distribution, and generate symbols including symbols in the form of quantized coefficients. 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 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, so that a symbol is represented, so that the size of a bit string for each symbol is reduced. Can be reduced. Therefore, the compression performance of image decoding may be improved through the entropy decoding method.

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

In the case of the intra mode, the intra prediction unit 240 may generate a prediction block by performing spatial prediction using pixel values of blocks already decoded 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 may be added through the adder 255, and the added block may pass through the filter unit 260. The filter unit 260 may apply at least one of a deblocking filter, SAO, and ALF to a reconstructed block or reconstructed picture. The filter unit 260 may output a reconstructed image, that is, a reconstructed image. The reconstructed image may be stored in the reference picture buffer 270 and used for inter prediction.

Hereinafter, a block means a unit of image encoding and decoding. The encoding or decoding unit for image encoding and decoding refers to a divided unit when encoding and decoding an image, and thus a coding unit (CU), a prediction unit (PU), and a transformation unit (TU) : Transform Unit, transform block. One block may be further divided into smaller sub-blocks. In addition, in this specification, “picture” may be used by being replaced with “frame”, “field”, and / or “slice” depending on the context, and such division can be easily performed 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 a P slice, a B slice, and a forward B slice according to context.

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

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

In the inter mode, the encoder and the decoder may derive motion information of a 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 may obtain motion information of a collocated block corresponding to a current block in a reconstructed neighboring block and / or a collocated picture that has already been reconstructed. By using, it is possible to improve the encoding / decoding efficiency. Here, the reconstructed neighboring block is a block in the current picture that is already encoded and / or decoded and reconstructed, and may include a block adjacent to the current block and / or a block located at an outer corner of the current block. Also, the encoder and the decoder may determine a predetermined relative position based on a block that is spatially the same as the current block in the call picture, and the determined relative position (which is spatially the same as the current block) The call block may be derived based on the inside and / or outside location of the block. Here, as an example, the call picture may correspond to one picture among reference pictures included in the reference picture list.

Meanwhile, a method for deriving motion information may vary according to a prediction mode of a current block. A prediction mode applied for inter prediction may include an Advanced Motion Vector Predictor (AMVP), merge, and the like.

For example, when the Advanced Motion Vector Predictor (AMVP) is applied, the encoder and the decoder may generate a predicted motion vector candidate list by using a motion vector of a reconstructed 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 candidate prediction motion vectors. The encoder may transmit a predicted motion vector index indicating the 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 may obtain a motion vector difference (MVD) between a motion vector of a current block and a predicted motion vector, and encode it and transmit it 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 may generate a merge candidate list using motion information of a reconstructed neighboring block and / or motion information of a call block. That is, if motion information of reconstructed neighboring blocks and / or call blocks exists, the encoder and decoder may use them as merge candidates for the current block.

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

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

Referring back to FIG. 3, the encoder and the decoder may generate a prediction block of the current block by performing motion compensation for the current block based on the derived motion information (S320). Here, the prediction block may mean a motion compensated block generated as a result of performing motion compensation on the current block. Also, a plurality of motion-compensated blocks may constitute one motion-compensated image. Accordingly, in the embodiments described below, the prediction block may be referred to as a 'motion compensated block' and / or a 'motion compensated image' depending on the context, and this classification is easy for those of ordinary skill in the art. You can do it.

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

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

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

The reference pictures may be allocated to the reference picture list in descending order, generally according to the reference picture number. Here, the reference picture number may mean a number assigned to each reference picture in a picture order count (POC) order, and the POC order may mean a display order and / or 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 allocated to the reference picture list may be rearranged by a reference picture list reordering (RPLR) or a memory management control operation (MMCO) command.

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

Bi-prediction may be used as a concept including both forward prediction, backward prediction, and bidirectional prediction, but in the embodiments described below, prediction using two reference pictures (L0 reference picture and L1 reference picture) is referred to as bidirectional prediction for convenience. That is, in the embodiments described below, bi-directional prediction may mean bi-prediction, and may be understood as a concept including both forward, backward, and bi-directional prediction using two reference pictures (L0 reference picture and L1 reference picture). . Further, even when bi-prediction is performed, forward prediction or backward prediction may be performed, but in the embodiments described below, prediction using only one reference picture is referred to as unidirectional prediction for convenience. That is, in the embodiments described below, the unidirectional prediction may mean a single prediction, and should be understood as a concept including only prediction using one reference picture. In addition, hereinafter, information indicating whether unidirectional prediction (uni-prediction) or bi-directional prediction (bi-prediction) is applied to a block on which prediction is performed is referred to as prediction direction information.

4 is a diagram schematically showing an embodiment of an 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 during 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 and a motion vector.

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

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

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

Hereinafter, motion compensation applied in bidirectional prediction is referred to as bidirectional motion compensation. In response to this, motion compensation applied in unidirectional prediction may be referred to as unidirectional motion compensation.

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

The image encoded in FIG. 5 corresponds to BasketballDrill. Here, BasketballDrill indicates the name of a test sequence used in the video encoding / decoding experiment. The size of the encoded image is 832x480, and the picture order count (POC) is 2. In addition, a quantization parameter (QP) value applied to the image of FIG. 5 is 32.

The encoder and decoder may use forward B pictures to increase 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 and L1 motion information). In the forward B picture, in general, the L0 reference picture list and the L1 reference picture list may be set identically. Hereinafter, in the present specification, when a 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 may determine whether the current picture is a forward B picture based on information transmitted from the encoder. It might be. For example, the coder may encode a flag indicating whether the L0 reference picture list and the L1 reference picture list are the same and transmit the flag to the decoder. At this time, the decoder may receive and decode the flag, and then determine whether the current picture is a forward B picture based on the decoded flag. As another example, the encoder may transmit a NAL unit type value or a 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. Accordingly, each block in the coded image may have up to 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, among blocks having two motion information, a block having the same L0 motion information (eg, reference picture number, motion vector) and L1 motion information (eg, reference picture number, motion vector) is the same. There can be multiple.

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

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

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

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

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

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

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

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

When the L0 temporal motion information and the L1 temporal motion information are the same, the encoder and the decoder may determine whether motion information of the reconstructed neighboring block exists (S620). For example, at this time, the encoder and decoder may determine whether there is a block having motion information among reconstructed neighboring blocks of a predetermined position and / or a position selected by a predetermined method. Here, the reconstructed neighboring block is a block in the current picture that is already encoded and / or decoded and reconstructed, and may include a block adjacent to the current block and / or a block located at an outer corner of the current block.

When the motion information of the reconstructed neighboring block does not exist (for example, if there is no block having motion information among the reconstructed neighboring blocks of a predetermined position and / or a position selected in a predetermined method), the encoder and the decoding The group may re-set the prediction direction information of the current block as unidirectional prediction (S630). Also, at this time, the encoder and the decoder may use only L0 temporal motion information as temporal motion information of the current block.

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

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

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

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

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

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

In another embodiment, the encoder and decoder may determine whether to perform the processes S620 to S640 based on the size of the current block. As an example, the encoder and decoder may determine whether the size of the current block is smaller than a predetermined size. Here, the current block may be a CU, PU and / or TU, and the predetermined size may be one of 8x8, 16x16 or 32x32, for example. At this time, the encoder and the decoder may perform processes 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 processes S620 to S640 when the L0 motion vector and / or the L1 motion vector corresponds to a zero vector (0,0) in motion information of a call block. In this case, the encoder and decoder in step S640 described above may reset the motion vector (s) corresponding to the zero vector (0,0). For example, the motion vector (s) corresponding to the zero vector (0,0) may be set as a motion vector of the reconstructed neighboring block, and as another example, a motion vector corresponding to the zero vector (0,0) ( S) 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 processes S620 to S640 when the L0 motion vector and / or the L1 motion vector do not correspond to the zero vector (0,0) in the motion information of the call block. In this case, in step S640 described above, the encoder and decoder may reset motion vector (s) not corresponding to the zero vector (0,0), and motion vector (s) not corresponding to the zero vector (0,0). ) May be reset to the motion vector of the reconstructed neighboring block.

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

On the other hand, when AMVP is applied, the encoder and / or the decoder may use a candidate having the smallest difference from a motion vector of a current block among prediction motion vector candidates in a prediction motion vector candidate list, as a prediction motion vector of the current block, and merge applied If possible, the encoder and / or the decoder may use a merge candidate that can provide optimal encoding efficiency among merge candidates in the merge candidate list as motion information for the current block. Since the predicted motion vector candidate list and the merge candidate list may each include temporal motion information and / or spatial motion information, as a result, motion information (eg, reference picture number, motion information, etc.) of the current block is restored. It can be derived based on the motion information of the block. Accordingly, in the above-described L1 temporal motion information resetting step (S640), the encoder and the decoder may reset the L1 temporal motion information based on the predicted motion vector candidate list of the current block and / or the merge candidate list of the current block. In this case, the step (S630) of determining whether or not the above-described restored neighboring block is present may be omitted. Hereinafter, in the embodiments described below, the motion information candidate list may be understood as a concept including a prediction motion vector candidate list and a merge candidate list.

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

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

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

In another embodiment, the encoder and decoder may use the first motion information candidate available in the motion information candidate list as L1 temporal motion information of the current block. In this case, the L1 reference picture number of the L1 temporal motion information is changed or set to the reference picture number of the first motion information candidate, and the L1 motion vector of the L1 temporal motion information is changed to the motion vector of the first motion information candidate or Can be set. At this time, 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 for determining the motion information candidate used as the L1 temporal motion information in the current block motion information candidate list is not limited to the above-described embodiment, and various conditions may be applied according to conditions and / or needs.

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

In the above-described embodiments, since the L0 temporal motion information and the L1 temporal motion information are temporally derived motion information, it is highly likely to correspond to motion information due to movement of an object. Therefore, the encoder and decoder search for motion information to be used as L1 temporal motion information of the current block in the reconstructed neighboring block and / or motion information candidate list, without selecting motion information with a zero vector (0,0). It is also possible to select motion information without vectors (0, 0). This is because a block having motion information corresponding to a zero vector (0,0) is more likely to correspond to a background than an object.

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

Further, in the above-described embodiments, the motion information selected from the motion information and the motion information candidate list of the reconstructed neighboring block may include both L0 motion information and L1 motion information, respectively. In this case, the encoder and 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. As an example, the encoder and decoder may use L0 motion information as motion information of the current block as L1 motion information from motion information of a reconstructed neighboring block and / or motion information selected from a motion information candidate list. At this time, if there is no L0 motion information in the motion information selected from the motion information and / or motion information candidate list of the reconstructed neighboring block, the encoder and decoder may use the L1 motion information as the L1 temporal motion information of the current block. . As another example, the encoder and decoder may use L1 motion information as L1 temporal motion information of a current block from motion information of a reconstructed neighboring block and / or motion information selected from a motion information candidate list. At this time, if the L1 motion information does not exist in the motion information selected from the motion information and / or motion information candidate list of the restored neighboring block, the encoder and decoder may use the L0 motion information as the L1 temporal motion information of the current block. .

Meanwhile, in order to reset the L1 temporal motion information (eg, L1 motion vector) of the current block in step S640 described above, the encoder and decoder do not use the restored motion information and / or motion information candidate list of the neighboring blocks. It might be. At this time, the encoder and the decoder may reset the L1 temporal motion information (eg, L1 motion vector) of the current block based on the L0 temporal motion information (eg, L0 motion vector) of the current block. Hereinafter, embodiments related to this will be described, which will be described based on a motion vector.

In one embodiment, the encoder and decoder L1 of the current block indicates motion information indicating a relative position moved based on a predetermined distance and / or direction from a position indicated by the L0 temporal motion information (L0 motion vector) of the current block. It can be used as temporal motion information (L1 motion vector). For example, the encoder and decoder are 1/4 pixel size (for example, (-1,0), (1,0), (1,0), in the vertical and / or horizontal direction at the position indicated by the L0 temporal motion information of the current block. 0, -1), (0,1), (-1, -1), (-1,1), (1, -1), (1,1), etc. where 1/4 pixel unit is 1 Motion information indicating the moved position as much as.) Can be used as L1 temporal motion information of the current block. As another example, the encoder and decoder are 1/2 pixel size in the vertical and / or horizontal direction (eg, (-2,0), (2,0), (,) in the position indicated by the L0 temporal motion information of the current block, ( 0, -2), (0,2), (-2, -2), (-2,2), (2, -2), (2,2), etc. where 1/4 pixel unit is 1 Motion information indicating the moved position as much as L1 temporal motion information of the current block. As another example, the encoder and decoder are integer pixel sizes (eg, (-4,0), (4,0), (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), etc. where 1/4 pixel units is 1 Applicable.) The motion information indicating the moved position may be used as the L1 temporal motion information of the current block. Meanwhile, since the motion vector includes a vertical component and a horizontal component, the above-described methods (moving by 1/4 pixel size, shifting by 1/2 pixel size, shifting by integer pixel size) include horizontal component and vertical direction. It may be applied independently to each component. At this time, the horizontal movement distance and the vertical movement distance may be different.

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

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

Meanwhile, in the above-described embodiment, the temporal motion information input in step S610 before resetting the temporal motion information may include a reference picture index as well as a motion vector. Here, the L0 motion vector and the L1 motion vector may be motion vectors derived temporally based on the call block as described above, and the L0 reference picture index and the L1 reference picture index are spatially derived reference pictures from the reconstructed neighboring blocks. It can be an index. At this time, the L0 reference picture index and the L1 reference picture index may be set to the smallest non-negative value among the reference picture indexes of the reconstructed neighboring blocks. Meanwhile, as another example, the L0 input reference picture index and the L1 input reference picture index may be set to 0 regardless of motion information of the reconstructed neighboring block.

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

Hereinafter, the temporal motion information input in step S610 before resetting the temporal motion information will be referred to as input temporal motion information (L0 input temporal motion information, L1 input temporal motion information) for convenience of description only in the embodiments of FIGS. 6 to 8 described below. . In addition, the motion vector included in the input temporal motion information is an input motion vector (L0 input motion vector, L1 input motion vector), and the reference picture index included in the input temporal motion information is an input reference picture index (L0 input reference picture index, L1 input) Reference picture index) and reference picture numbers included in the input temporal motion information are referred to as input reference picture numbers (L0 input reference picture number, L1 input reference picture number).

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

In an 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 decoder can use the restored motion information of the neighboring block as L1 temporal motion information of the current block. At this time, the encoder and the decoder may derive the final L1 reference picture index by resetting the L1 input reference picture index to the reference picture index of the reconstructed neighboring block. In another embodiment, the encoder and decoder may derive the final L1 reference picture index by resetting the L1 input reference picture index value to a predetermined fixed reference picture index value.

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

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 that is not the same as the L0 input reference picture index. For example, a reference picture index that is not the same as the L0 input reference picture index may be present in the reference picture index of the reconstructed neighboring block. At this time, for example, the encoder and the decoder may use the most frequently used reference picture index among reference picture indices that are not the same as the L0 input reference picture index, for resetting the L1 input reference picture index. As another example, in this case, the encoder and decoder may use a reference picture index having the smallest non-negative value among reference picture indices that are not the same as the L0 input reference picture index, for resetting the L1 input reference picture index.

On the other hand, as described above, the encoder and decoder can derive the final L1 temporal motion vector by resetting the L1 input motion vector value from the L1 input temporal motion information to the same value as the motion vector of the reconstructed neighboring block. At this time, the motion vector of the reconstructed neighboring block may be scaled and used 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 a reset process, or may be used as the final L1 temporal motion information through a reset process as in the above-described embodiment. At this time, the reference picture corresponding to the motion vector of the reconstructed neighboring block and the reference picture indicated by the final L1 reference picture index may be different. In this case, the encoder and decoder may perform scaling on the motion vector of the reconstructed neighboring block and use the scaled motion vector as the final L1 temporal motion information of the current block.

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

In an embodiment, the encoder and the decoder may use only a motion vector other than a zero vector (0, 0) among motion vectors of the reconstructed neighboring blocks to reset the L1 input motion vector. At this time, as an example, the L1 input reference picture index may be used as the final L1 temporal motion information without a reset process. As another example, the L1 input reference picture index value may be reset to the reference picture index value of the reconstructed neighboring block, and the reset reference picture index may be used as the final L1 temporal motion information. As another example, the L1 input reference picture index value may be reset to a predetermined fixed reference picture index value. Since specific embodiments of each of the above have been described above, it will be omitted here.

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

In another embodiment, the encoder and decoder only set motion vectors in which the difference from the current block L0 temporal motion information (L0 motion vector) of a reconstructed neighboring block motion vector is less than or equal to a predetermined threshold, for resetting the L1 input motion vector. Can be used. In this case, the encoder and decoder may use only motion vectors that are not identical to the L0 temporal motion information (L0 motion vector) of the current block among the motion vectors of the reconstructed neighboring blocks. At this time, as an example, the L1 input reference picture index may be used as the final L1 temporal motion information without a reset process. As another example, the L1 input reference picture index value may be reset to the reference picture index value of the reconstructed neighboring block, and the reset reference picture index may be used as the final L1 temporal motion information. As another example, the L1 input reference picture index value may be reset to a predetermined fixed reference picture index value. Since specific embodiments of each of the above have been described above, it will be omitted here.

The combination of the 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 combinations of various forms as well as the above-described embodiments may be provided according to implementation and / or needs. 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 may set the prediction direction information of the current block to unidirectional prediction again. At this time, the encoder and the decoder may use only L0 temporal motion information as temporal motion information of the current block. This method can be applied to the present invention in combination with the above-described embodiments.

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

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

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

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

In another embodiment, the encoder and decoder may scan a plurality of blocks existing in a predetermined position among reconstructed neighboring blocks in a predetermined order. At this time, the encoder and decoder may use motion information of a first block in which motion information is present in scan order, as L1 temporal motion information of a current block. The scan target block and scan order may be determined in various forms. For example, the encoder and the decoder may scan neighboring blocks in order of the top left block (F), top leftmost block (B), and top rightmost block (B). As another example, the encoder and the decoder may block neighboring blocks in the order of top left block (F), top leftmost block (G), top right corner block (C), bottom left corner block (D), and top left corner block (E). You can also scan. As another example, the encoder and decoder may scan neighboring blocks in the order of the left bottom block (A), top rightmost block (B), and top left corner block (E). As another example, the encoder and the decoder are adjacent blocks in the order of the bottom left block (A), the top right block (B), the top right corner block (C), the bottom left corner block (D), and the top left corner block (E). You can also scan As another example, the encoder and decoder are the lower left block (A), upper right block (B), upper right corner block (C), lower left corner block (D), upper left corner block (E), upper left block ( It is also possible to scan the neighboring blocks in the order of F) and upper 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 among reconstructed neighboring blocks, and the derived intermediate value may be L1 temporal motion information of the current block. Can be used as For example, the plurality of blocks may be a top left block (F), a top leftmost block (G), a top right corner block (C), a bottom left corner block (D), and a top left corner block (E). .

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

Hereinafter, an embodiment of a process for deriving temporal motion information according to the embodiments of FIGS. 6 and 7 will be described from the viewpoint of the decoder.

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

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

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

mvL1Col = mvL0A

Otherwise, if the top leftmost block (B (xP, yP-1)) adjacent to the top of the current block is present, the top leftmost block is not a block encoded in intra mode, predFlagL0B is '1' and mvL0B If is not (0,0), the encoder and decoder can perform the following process. Here, B may indicate that predFlagL0B and mvL0B are information regarding the uppermost block B on the left.

mvL1Col = mvL0B

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

mvL1Col = mvL0E

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

avilableFlagL1Col = 0

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

availableFlagCol = availableFlagL0Col || availableFlagL1Col

predFlagLXCol = availableFlagLXCol

Here, availableFlagCol indicates whether temporal motion information has been derived, and predFlagLXCol may indicate the presence or absence of final temporal motion information for each of the L0 temporal motion information and the L1 temporal motion information.

8 is a block diagram schematically showing an embodiment of an inter prediction apparatus capable of performing a process of deriving temporal motion information according to the embodiment of FIG. 6. The inter-prediction apparatus according to the embodiment of FIG. 8 includes a temporal motion information determination unit 810, a reconstructed neighboring block motion information determination unit 820, a prediction direction information reset and L0 motion information setting unit 830, and L1 temporal motion information A reset unit 840 may be included.

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

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

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

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

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

When the motion information of the restored neighboring block is present, the L1 temporal motion information resetting unit 840 may reset the L1 temporal motion information of the current block to the restored motion information of the neighboring block. That is, the inter prediction apparatus may use the reconstructed neighboring block motion information as L1 temporal motion information of the current block. At this time, as an example, when the L1 temporal motion information resetting unit 840 searches for motion information to be used as the L1 temporal motion information of the current block in the restored neighboring block, motion information having a zero vector (0,0) is not selected. It is also possible to select only motion information that does not have a zero vector (0,0). 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. Since the specific embodiment of each of the above-described methods has been described in FIGS. 6 and 7, it will be omitted here.

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

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

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

Referring to FIG. 9, the encoder and decoder determine whether L0 temporal motion information and L1 temporal motion information are the same in temporal motion information derived based on a call block, that is, L0 reference picture number and L1 reference picture number are the same and L0 motion It may be determined whether the vector and the L1 motion vector are the same (S910). Hereinafter, in the embodiments of FIGS. 9 to 11 described later, for convenience of explanation, temporal motion information input in step S910 before resetting temporal motion information is input temporal motion information (L0 input temporal motion information, L1 input temporal motion information). do. In addition, the motion vector included in the input temporal motion information is an input motion vector (L0 input motion vector, L1 input motion vector), and the reference picture index included in the input temporal motion information is an input reference picture index (L0 input reference picture index, L1 input) Reference picture index) and reference picture numbers included in the input temporal motion information are referred to as input reference picture numbers (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, the L0 input reference picture number and the L1 input reference picture number are not the same, and / or the L0 input motion vector and the L1 input motion vector are not the same. , The encoder and decoder may use input temporal motion information derived based on a call block as the temporal motion information of the current block. When AMVP is applied, temporal motion information of the current block may be determined or registered as a prediction motion vector candidate of the current block. Also, when merge is applied, temporal motion information of the current block may be determined or registered as a merge candidate of the current block.

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

Hereinafter, in the embodiments of FIGS. 9 to 11, for convenience of description, a call block used for deriving input temporal motion information is referred to as a first call block, and will be described later while being subject to determination of presence or absence of motion information as in step S920. As in step S940, the call block used for resetting the L1 input temporal motion information is referred to as a second call block. In addition, a call picture including a first call block is called a first call picture, and a call picture including a second call block is called a second call picture. Here, as an example, the first call picture and the second call picture may each correspond to one picture among reference pictures included in the reference picture list.

When the motion information of the second call block does not exist (for example, if there is no block having motion information among the second call blocks at a predetermined position and / or a position selected by a predetermined method), the encoder and the decoding The group may re-set the prediction direction information of the current block as a one-way prediction (S930). Also, at this time, the encoder and decoder can use only L0 input temporal motion information as temporal motion information of the current block.

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

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

On the other hand, in the above-described embodiment, it is determined whether to perform the processes S920 to S940 based on the identity of the L0 input temporal motion information and the L1 input temporal motion information, but the encoder and decoder perform the S920 to S940 processes based on other conditions. You can also decide

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

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

In another embodiment, the encoder and the decoder may determine whether to perform the processes S920 to S940 based on information on whether motion information is present in the first call block. For example, the encoder and the decoder may perform processes S920 to S940 when motion information does not exist in the first call block. In this case, in step S940 described above, the L0 input temporal motion information, not the L1 input temporal motion information, may be reset. That is, the encoder and the decoder may set the L0 input temporal motion information as motion information of the second call block, and may perform unidirectional prediction rather than bidirectional prediction on the current block. In addition, if there is no motion information in the first call block, in step S940, the encoder and decoder may reset both the L0 input temporal motion information and the L1 input temporal motion information. That is, the encoder and the decoder may reset both the L0 input temporal motion information and the L1 input temporal motion information to motion information of the second call block, and may perform bidirectional prediction on the current block.

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

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

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

In the above-described embodiments, since the L0 input temporal motion information and the L1 input temporal motion information are temporally derived motion information, it is highly likely to correspond to motion information due to movement of an object. Accordingly, the encoder and decoder search for motion information to be used as the final L1 temporal motion information of the current block in the second call block, without selecting motion information having a zero vector (0,0), a zero vector (0,0) It is also possible to select motion information that does not have. This is because a block having motion information corresponding to a zero vector (0,0) is more likely to correspond to a background than an object.

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

* In addition, in the above-described embodiments, the motion information of the second call block may include both L0 motion information and L1 motion information. In this case, the encoder and the decoder may determine one of the L0 motion information and the L1 motion information as motion information to be used as the final L1 temporal motion information of the current block. As an example, the encoder and decoder may use L0 motion information of the second call block as final L1 temporal motion information of the current block. At this time, if there is no L0 motion information in the second call block, the encoder and the decoder may use the L1 motion information of the second call block as the final L1 temporal motion information for the current block. As another example, the encoder and decoder may use L1 motion information of the second call block as final L1 temporal motion information of the current block. At this time, when the L1 motion information does not exist in the second call block, the encoder and the decoder may use the L0 motion information of the second call block as the final L1 temporal motion information for the current block.

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

In one embodiment, the encoder and decoder move within a first call picture to indicate a relative position moved based on a predetermined distance and / or direction from a position indicated by motion information (motion vector) of the first call block. Information may be used as the final L1 temporal motion information (L1 motion vector) of the current block. In one example, the encoder and decoder are 1/4 pixel size in the vertical and / or horizontal direction (eg, (-1,0), (1,0), () at the position indicated by the motion information of the first call block. 0, -1), (0,1), (-1, -1), (-1,1), (1, -1), (1,1), etc. where 1/4 pixel unit is 1 Motion information indicating the moved position as much as.) Can be used as the final L1 temporal motion information of the current block. As another example, the encoder and decoder are 1/2 pixel size in the vertical and / or horizontal direction at the position indicated by the motion information of the first call block (for example, (-2,0), (2,0), ( 0, -2), (0,2), (-2, -2), (-2,2), (2, -2), (2,2), etc. where 1/4 pixel unit is 1 Motion information indicating the moved position as much as.) Can be used as the final L1 temporal motion information of the current block. As another example, the encoder and decoder are integer pixel sizes (for example, (-4,0), (4,0), (0) in the vertical and / or horizontal direction at the position indicated by the motion information of the first call block. , -4), (0,4), (-4, -4), (-4,4), (4, -4), (4,4), etc. where 1/4 pixel units is 1 If applicable, motion information indicating the moved position may be used as the final L1 temporal motion information of the current block. Meanwhile, since the motion vector includes a vertical component and a horizontal component, the above-described methods (moving by 1/4 pixel size, shifting by 1/2 pixel size, shifting by integer pixel size) include horizontal component and vertical direction. It may be applied independently to each component. At this time, the horizontal movement distance and the vertical movement distance may be different.

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

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

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

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

In an 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 decoder can use the motion information of the second call block as the final L1 temporal motion information of the current block. At this time, the encoder and the decoder may derive the final L1 reference picture index by resetting the L1 input reference picture index to the reference picture index of the second call block. In another embodiment, the encoder and decoder may derive the final L1 reference picture index by resetting the L1 input reference picture index value to a predetermined fixed reference picture index value.

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

In 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 that is not the same as the L0 input reference picture index. Among the reference picture indices of the reconstructed neighboring block, a reference picture index that is not the same as the L0 input reference picture index may exist. At this time, for example, the encoder and the decoder may use the most frequently used reference picture index among reference picture indices that are not the same as the L0 input reference picture index, for resetting the L1 input reference picture index. As another example, in this case, the encoder and decoder may use a reference picture index having the smallest non-negative value among reference picture indices that are 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 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. At this time, the motion vector of the second call block may be scaled and used according to the L1 input reference picture index and / or the reset L1 reference picture index. The L1 input reference picture index may be used as a final L1 reference picture index without a reset process, or may be used as a final L1 reference picture index through a reset process as in the above-described 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. In this case, the encoder and decoder may perform scaling on the motion vector of the second call block and use the scaled motion vector as the final L1 temporal motion vector of the current block.

The above-described embodiments may be combined and applied in various ways according to a process of resetting a motion vector and a process of resetting a reference picture index (eg, RefIdxLX, X = 0,1). Hereinafter, in embodiments described below, 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 decoder reset the L1 input motion vector to one of the motion vectors of the second call block.

In an embodiment, the encoder and decoder may 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 may 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 final L1 temporal motion information. At this time, as an example, the L1 input reference picture index may be used as the final L1 temporal motion information without a reset process. That is, the encoder and the decoder may allocate the L1 input reference picture index as it is to the L1 temporal motion information of the current block. As another example, the L1 input reference picture index value may be reset to a predetermined fixed reference picture index value. That is, the encoder and the decoder may allocate a predetermined fixed reference picture index value to the L1 temporal motion information of the current block, and the predetermined fixed reference picture index may be used as the final L1 temporal motion information.

In another embodiment, the encoder and decoder may 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 may be the second call picture as in the above-described embodiment. Can be derived from At this time, the encoder and decoder derive a motion vector in which the 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, in order to reset the L1 input motion vector. can do. The encoder and decoder can perform scaling on the derived motion vector, and the scaled motion vector can be used as the final L1 temporal motion information. At this time, as an example, the L1 input reference picture index may be used as the final L1 temporal motion information without a reset process. That is, the encoder and the decoder may allocate the L1 input reference picture index as it is to the L1 temporal motion information of the current block. As another example, the L1 input reference picture index value may be reset to a predetermined fixed reference picture index value. That is, the encoder and the decoder may allocate a predetermined fixed reference picture index value to the L1 temporal motion information of the current block, and the predetermined fixed reference picture index may be used as the final L1 temporal motion information.

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

In another embodiment, the encoder and 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, as in the above-described embodiment, and the second call block Can be derived from the second call picture. Here, the second call picture may be, for example, the most recently decoded reference picture among the reference pictures in the L1 reference picture list that is not the same as the first call picture. As another example, the encoder and the decoder may select the reference picture with the most frequent use as the second call picture based on the reference picture number of the reconstructed neighboring block. At this time, the encoder and decoder derive a motion vector in which the 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, in order to reset the L1 input motion vector. can do. The encoder and decoder can perform scaling on the derived motion vector, and the scaled motion vector can be used as the final L1 temporal motion information. At this time, as an example, the L1 input reference picture index may be used as the final L1 temporal motion information without a reset process. That is, the encoder and the decoder may allocate the L1 input reference picture index as it is to the L1 temporal motion information of the current block. As another example, the L1 input reference picture index value may be reset to a predetermined fixed reference picture index value. That is, the encoder and the decoder may allocate a predetermined fixed reference picture index value to the L1 temporal motion information of the current block, and the predetermined fixed reference picture index may be used as the final L1 temporal motion information.

The combination of the 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 combinations of various forms as well as the above-described embodiments may be provided according to implementation and / or needs. have.

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

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

The encoder and decoder may determine the second call block based on the same location block that is spatially identical to the current block in the second call picture. In FIG. 10, block 1010 represents a current block, and block 1020 represents a co-located block in a second call picture. Here, the second call picture may be determined in various ways.

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

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

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

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

The method for determining the second call picture is not limited to the above-described embodiment, and the second call picture may be determined in other ways depending on implementation and / or needs.

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

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

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

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

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

The method for 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 needs.

11 is a block diagram schematically showing an embodiment of an inter prediction apparatus capable of performing a process of deriving temporal motion information according to the embodiment of FIG. 9. 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, and L1 temporal motion information A reset unit 1140 may be included.

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 in the input temporal motion information are the same, that is, the L0 input reference picture number and the L1 input reference picture number are the same. And it can be determined whether the L0 input motion vector and the L1 input motion vector are the same.

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

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

The second call block motion information determination unit 1120 may determine whether motion information of the second call block exists. When there is no motion information of the second call block (for example, when there is no block having motion information among the second call blocks at a predetermined position and / or a position selected by a predetermined method), prediction direction information The process of resetting the prediction direction information and setting the L0 motion information by the reset and L0 motion information setting unit 1130 may be performed. Further, when the motion information of the second call block exists (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), L1 temporal motion The reset process by the information reset unit 1140 may be performed.

If the motion information of the second call block does not exist, the prediction direction information reset and the L0 motion information setting unit 1130 may set the prediction direction information of the current block back to unidirectional prediction. In addition, at this time, the prediction direction information reset and the L0 motion information setting unit 1130 may set only the L0 input temporal motion information among the input temporal motion information as the final temporal motion information of the current block.

When the motion information of the second call block exists, the L1 temporal motion information reset unit 1140 may reset the L1 input temporal motion information of the current block to the motion information of the second call block. That is, the inter prediction apparatus may use motion information of the second call block as final L1 temporal motion information of the current block. At this time, when the motion information of the second call block includes a zero vector (0,0), the L1 temporal motion information reset unit 1140 determines the motion information of the block located around the second call block as the last of the current block. It can also be used as L1 temporal motion information. Since the specific embodiment of each of the above-described methods has been described in FIGS. 6 and 7, it will be omitted here.

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

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

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

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

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

Meanwhile, in the above-described embodiment, the encoder and the decoder may derive L1 motion information based on the L0 motion information. For example, it is assumed that the L0 motion information is motion information derived based on a call block. In this case, as described above, the encoder and decoder may use spatially derived spatial motion information based on the reconstructed neighboring block as L1 motion information. At this time, as an example, the encoder and the decoder may derive only motion information identical or similar to the L0 motion information as spatial motion information to be used as the L1 motion information. As another example, the encoder and the decoder may derive only motion information that is not the same as L0 motion information, as spatial motion information to be used as L1 motion information. At this time, the encoder and the decoder may derive only motion information in which a difference from the L0 motion information is equal to or less than a predetermined threshold value, as a spatial motion base to be used as 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, and / or motion information of a neighboring block, 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 be changed according to implementation and / or needs.

Meanwhile, when the L0 motion information and / or the L1 motion information are spatially derived based on the motion information of the reconstructed neighboring block, the reconstructed neighboring block motion information includes spatially derived spatial motion information and temporally derived temporal motion. It may contain all information. At this time, the encoder and the decoder may derive the L0 motion information of the current block and / or the L1 motion information of the current block using only spatially derived spatial motion information among the motion information of the reconstructed neighboring blocks.

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

Meanwhile, L0 motion information and L1 motion information in the derived motion information of the current block may be identical to each other. Accordingly, when the L0 motion information and the L1 motion information are the same, the encoder and the decoder may re-set the prediction direction information of the current block as unidirectional prediction. At this time, the encoder and the decoder may 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 process of deriving motion information according to the embodiment of FIG. 12. The inter-prediction apparatus according to the embodiment of FIG. 13 may include an L0 motion information setting unit 1310, an L1 motion information setting unit 1320, and a motion information integration unit 1330.

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

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

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

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

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

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

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

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

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

Hereinafter, in the embodiments of FIGS. 14 to 15 to be described later, for convenience of explanation, temporal motion information input in step S1410 before resetting temporal motion information is input temporal motion information (L0 input temporal motion information, L1 input temporal motion information). do. At this time, the input temporal motion information may correspond to temporal motion information derived based on a call block. In addition, the motion vector included in the input temporal motion information is an input motion vector (L0 input motion vector, L1 input motion vector), and the reference picture index included in the input temporal motion information is an input reference picture index (L0 input reference picture index, L1 input) Reference picture index) and reference picture numbers included in the input temporal motion information are referred to as input reference picture numbers (L0 input reference picture number, L1 input reference picture number). Further, in the embodiments described below, the reference picture indicated by the L0 input reference picture number is referred to as an L0 reference picture, and the reference picture indicated by the L1 input reference picture number is referred to as an L1 reference picture.

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

When the L0 input temporal motion information and the L1 input temporal motion information are the same, the encoder and the decoder may search 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 may correspond to the same picture as the L0 reference picture. Therefore, in the embodiment described below, the L1 reference picture may mean the same picture as the L0 reference picture.

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

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

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

In one embodiment, the encoder and decoder in the L1 reference picture, centering on the position indicated by the L0 input temporal motion information (motion vector), the motion information indicating the position within a predetermined range is the final L1 temporal motion information Can be used as (L1 motion vector). Specifically, the predetermined range corresponds to a range including a position within + T and / or -T distance in the vertical and / or horizontal direction, centered on the position indicated by the L0 input temporal motion information in the L1 reference picture. Can be. Here, as an example, T may be a value indicating a distance in units of 1/4 pixels, and in another example, T may be a value indicating a distance in units of 1/2 pixels. As another example, T may be a value indicating a distance in units of integer pixels. When an integer pixel unit is used, since an interpolation process may not be performed in motion compensation, computational complexity may be reduced.

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

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

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

On the other hand, in the above-described embodiment, it is determined whether to perform the processes S1420 to S1430 based on the identity of the L0 input temporal motion information and the L1 input temporal motion information, but the encoder and decoder perform the S1420 to S1430 processes based on other conditions. You can also decide

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

In another embodiment, the encoder and the decoder may determine whether to perform the processes 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 processes S1420 to S1430 when there is no motion information in the call block. In this case, in step S1430 described above, the L0 input temporal motion information, not the L1 input temporal motion information, may be reset. That is, the encoder and decoder may reset the L0 input temporal motion information to motion information of the L1 reference picture, and perform unidirectional prediction rather than bidirectional prediction on the current block. In addition, if there is no motion information in the call block, in step S1430, the encoder and decoder may reset both the L0 input temporal motion information and the L1 input temporal motion information. That is, the encoder and the decoder can reset both 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 processes S1420 to S1430 when the L0 motion vector and / or the L1 motion vector corresponds to a zero vector (0,0) in motion information of a call block. In this case, the encoder and decoder in step S1430 described above 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 (s) corresponding to the zero vector (0,0) ) May be set as a motion vector of the reconstructed neighboring block, and as another example, the motion vector (s) corresponding to the zero vector (0,0) may be set as a motion vector of a block located around the call block. have. In another embodiment, the encoder and the decoder may perform processes S1420 to S1430 when the L0 motion vector and / or the L1 motion vector do not correspond to the zero vector (0,0) in the motion information of the call block. In this case, in step S1430 described above, the encoder and decoder may reset motion vector (s) not corresponding to the zero vector (0,0), and motion vector (s) not corresponding to the zero vector (0,0). ) May be reset to a motion vector of the L1 reference picture.

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

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

In the above-described embodiment, the input temporal motion information input in step S1410 may include an input reference picture index as well as an input motion vector. Here, the L0 input motion vector and the L1 input motion vector may be motion vectors derived temporally based on a call block as described above, and the L0 input reference picture index and L1 input reference picture index are spatially derived from the reconstructed neighboring blocks. It may be a derived reference picture index. At this time, the L0 input reference picture index and the L1 input reference picture index may be set to the smallest non-negative value among the reference picture indexes of the reconstructed neighboring blocks. Meanwhile, as another example, the L0 input reference picture index and the L1 input reference picture index may be set to 0 regardless of motion information of the reconstructed neighboring block.

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

Meanwhile, as described above, the encoder and 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. At this time, the motion vector of the L1 reference picture may be scaled and used according to the L1 input reference picture index and / or the reset L1 reference picture index. The L1 input reference picture index may be used as a final L1 reference picture index without a reset process, or may be used as a final L1 reference picture index through a reset process as in the above-described 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. In this case, the encoder and decoder may perform scaling on the motion vector of the L1 reference picture and use the scaled motion vector as the final L1 temporal motion vector of the current block.

In addition, in the above-described embodiments, the reset L1 temporal motion information may be the same as the L0 temporal motion information of the current block. Accordingly, 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 re-set the prediction direction information of the current block as unidirectional prediction. At this time, the encoder and the decoder may use only L0 temporal motion information as temporal motion information of the current block. This method can be applied to the present invention in combination with the above-described embodiments.

* FIG. 15 is a block diagram schematically showing an embodiment of an inter prediction apparatus capable of performing a process of deriving temporal motion information according to the embodiment of FIG. 14. The inter prediction apparatus according to the embodiment of FIG. 15 may include a temporal motion information determining unit 1510, a motion predicting unit 1520, and an L1 temporal motion information resetting unit 1530.

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

Referring to FIG. 15, referring to FIG. 11, the temporal motion information determination unit 1510 determines whether the L0 input temporal motion information and the L1 input temporal motion information in the input temporal motion information are the same, that is, the L0 input reference picture number and L1 It is possible to determine whether the input reference picture number is the same and the L0 input motion vector and the L1 input motion vector are the same.

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

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

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

In an embodiment, the motion prediction unit 1520 may derive an area that is best matched or similar to an input block (original block) corresponding to the current block in the L1 reference picture. At this time, the motion prediction unit 1520 may derive motion information to be used as the final L1 temporal motion information of the current block based on the derived area. For example, the motion prediction unit 1520 may derive a motion vector to be used as the final L1 temporal motion information based on the position of the block corresponding to the derived area and the position of the current block, and corresponding to the derived area A reference picture index (and / or reference picture number) to be used as the final L1 temporal motion information may be derived based on the block.

Meanwhile, when the motion predictor 1520 corresponds to a component on the encoder side, the encoder may include motion information derived from the L1 reference picture in the bitstream by the above method and transmit it 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 motion vector to a decoder, respectively. At this time, the encoder may obtain a difference value between the actual motion vector of the current block and the motion vector derived from the L1 reference picture, and then transmit the difference value to the decoder.

In this case, the decoder may determine motion information to be used as the final L1 temporal motion information based on the transmitted motion information. That is, when the motion predicting unit 1520 corresponds to a component on the decoder side, the motion predicting unit 1520 is based on motion information (eg, motion information transmitted from an encoder) from the outside. It is possible to determine motion information to be used as L1 temporal motion information.

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

The above-described embodiments of FIGS. 6 to 15 may be individually applied, but may be combined and applied in various ways according to the encoding mode of each block. Hereinafter, in embodiments described below, a block in which the encoding mode is a merge mode is referred to as a merge block. Blocks other than the merge block may include, for example, a block in which the encoding mode is AMVP mode. Further, in the embodiments described below, the current block may correspond to one of a merge block or a block other than a merge block, depending on the case.

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

In another embodiment, the method for deriving temporal motion information according to the embodiments of FIGS. 9 to 11 may be applied to the merge block, and the method for deriving temporal motion information according to FIGS. 14 and 15 may be applied to a block other than the merge block. At this time, in the merge block, when the L0 input temporal motion information and the L1 input temporal motion information are the same, the motion information of the newly derived call block, not the call block used to derive the input temporal motion information, is the final L1 temporal motion information of the current block. Can be used as In addition, in a block other than the merge block, when the L0 input temporal motion information and the L1 input temporal motion information are the same, the motion information of the L1 reference picture may be used as the final L1 temporal motion information of the current block.

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

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

In the above-described embodiments, the methods are described based on a flow chart 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 a different order or simultaneously with the other steps as described above. You can. In addition, those skilled in the art may recognize that steps shown in the flowchart are not exclusive, other steps are included, or one or more steps in the flowchart may be deleted without affecting the scope of the present invention. You will understand.

The above-described embodiment includes examples of various aspects. It is not possible to describe all possible combinations for representing various aspects, but a person skilled in the art will recognize that other combinations are possible. Accordingly, the present invention will be said to include all other replacements, modifications and changes that fall within the scope of the following claims.

Claims (3)

Determining a call picture of the current block based on the call picture information; Here, the call picture information is information specifying a picture determined as a call picture of the current block among reference pictures in a 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 either the first block including the position of the lower-right pixel of the current block or the second block including the 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 for the current block based on the derived motion vector,
The call picture information is transmitted from the encoder, characterized in that the video decoding method. Deriving a motion vector of the 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 either the first block including the position of the lower-right pixel of the current block or the second block including the 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 call picture information for the call picture into a bitstream,
The call picture information is information specifying a picture determined as a call picture of the current block among reference pictures in a reference picture list, and is signaled to a decoder through the bitstream. A computer-readable recording medium storing a bitstream received by an image decoding apparatus and used to reconstruct a current block included in an image,
The bitstream includes call picture information,
The call picture information is used to determine a call picture of the current block, and is information identifying a picture determined as a call picture of the current block among reference pictures in a reference picture list,
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,
The call block is determined according to either the first block including the position of the lower-right pixel of the current block or the second block including the center position of the current block,
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 the motion vector of the current block,
The motion vector of the current block is used to perform motion compensation for the current block, a computer readable recording medium storing a bitstream.

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